Communication system, base station, user equipment

Abstract

A communication system that can suppress a decrease in transmission speed is provided. The eNB and the UE communicate using self - contained sub - frames. The self - contained sub - frame includes a downlink signal transmitted from the eNB to the UE and an uplink signal transmitted from the UE to the eNB in response to the downlink signal. The uplink signal is configured to include an uplink control signal indicating information for controlling the transmission of the uplink signal and uplink user data transmitted before and after the uplink control signal. The eNB notifies the UE of the structure of the uplink signal. The eNB can pre - determine a re - transmission schedule for re - transmitting the downlink signal before the first transmission of the downlink signal.

Description

[0001] This application is a divisional application of an application with an application date of "August 3, 2017", an application number of "201780058666.4", and a title of "Communication System". Technical Field

[0002] The present invention relates to a communication system for performing wireless communication between a communication terminal device such as a mobile terminal device and a base station device. Background Art

[0003] In the 3GPP (3rd Generation Partnership Project), which is a standardization organization for mobile communication systems, a communication method called Long Term Evolution (LTE) in the radio section and System Architecture Evolution (SAE) in the overall system structure including the core network and the radio access network (hereinafter also collectively referred to as the network) has been studied (for example, Non-Patent Documents 1 to 5). This communication method is also called a 3.9G (3.9th generation) system.

[0004] As an access method for LTE, OFDM (Orthogonal Frequency Division Multiplexing) is used in the downlink direction, and SC-FDMA (Single Carrier Frequency Division Multiple Access) is used in the uplink direction. In addition, unlike W-CDMA (Wideband Code Division Multiple Access), LTE does not include circuit switching and is only a packet communication method.

[0005] Use Figure 1 to explain the decision matters related to the frame structure of the LTE system in 3GPP described in Non-Patent Document 1 (Chapter 5). Figure 1 It is an explanatory diagram showing the structure of a radio frame used in a communication system of the LTE method. Figure 1In it, a radio frame is 10 ms. The radio frame is divided into 10 subframes of equal size. The subframe is divided into two slots of equal size. The first subframe and the sixth subframe of each radio frame contain downlink synchronization signals. There are a primary synchronization signal (P-SS) and a secondary synchronization signal (S-SS) in the synchronization signal.

[0006] Non-patent Document 1 (Chapter 5) describes the decisions related to the channel structure in the LTE system in 3GPP. It is assumed that the same channel structure as that of non-CSG cells is also used in CSG (Closed Subscriber Group) cells.

[0007] The physical broadcast channel (PBCH) is a downlink transmission channel from a base station device (hereinafter sometimes simply referred to as "base station") to a communication terminal device such as a mobile terminal device (hereinafter sometimes simply referred to as "mobile terminal") (hereinafter sometimes simply referred to as "communication terminal"). The BCH transport block is mapped to four subframes at 40 ms intervals. There is no clear signaling for the 40 ms timing.

[0008] The physical control format indicator channel (PCFICH) is a downlink transmission channel from the base station to the communication terminal. The PCFICH notifies the communication terminal from the base station of the number of OFDM (Orthogonal Frequency Division Multiplexing) symbols for PDCCHs. The PCFICH is transmitted for each subframe.

[0009] The Physical Downlink Control Channel (PDCCH) is a downlink transmission channel from the base station to the communication terminal. The PDCCH notifies the resource allocation information of the Downlink Shared Channel (DL-SCH), which is one of the transmission channels described later, the resource allocation information of the Paging Channel (PCH), which is one of the transmission channels described later, and the Hybrid Automatic Repeat reQuest (HARQ) information related to the DL-SCH. The PDCCH transmits an Uplink Scheduling Grant. The PDCCH transmits the response signal, i.e., Ack (Acknowledgement) / Nack (Negative Acknowledgement), for the uplink transmission. The PDCCH is also referred to as the L1 / L2 control signal.

[0010] The Physical Downlink Shared Channel (PDSCH) is a downlink transmission channel from the base station to the communication terminal. The Downlink Shared Channel (DL-SCH) as a transmission channel and the PCH as a transmission channel are mapped to the PDSCH.

[0011] The Physical Multicast Channel (PMCH) is a downlink transmission channel from the base station to the communication terminal. The Multicast Channel (MCH) as a transmission channel is mapped in the PMCH.

[0012] The Physical Uplink Control Channel (PUCCH) is an uplink transmission channel from the communication terminal to the base station. The PUCCH transmits the response signal, i.e., Ack / Nack, for the downlink transmission. The PUCCH transmits a CQI (Channel Quality Indicator) report. The CQI is quality information indicating the quality of the received data or the communication line quality. The PUCCH also transmits a Scheduling Request (SR).

[0013] The Physical Uplink Shared Channel (PUSCH) is an uplink transmission channel from a communication terminal to a base station. The Uplink Shared Channel (UL-SCH), which is one of the transport channels, is mapped onto the PUSCH.

[0014] The Physical Hybrid ARQ Indicator Channel (PHICH) is a downlink transmission channel from a base station to a communication terminal. The PHICH transmits an Ack / Nack, which is a response signal for uplink transmission. The Physical Random Access Channel (PRACH) is an uplink transmission channel from a communication terminal to a base station. The PRACH transmits a random access preamble.

[0015] The downlink reference signal (Reference Signal: RS) is a symbol known in a communication system using the LTE method. The following five types of downlink reference signals are defined: the Cell-specific Reference Signal (CRS), the MBSFN Reference Signal, the UE-specific Reference Signal, which is a demodulation reference signal (DM-RS) for data demodulation, the Positioning Reference Signal (PRS), and the Channel State Information Reference Signal (CSI-RS). As a measurement at the physical layer of a communication terminal, there is a measurement of the Reference Signal Received Power (RSRP).

[0016] The transport channel described in Non-Patent Document 1 (Chapter 5) will be explained. The Broadcast Channel (BCH) among the downlink transport channels is broadcast over the entire coverage area of its base station (cell). The BCH is mapped onto the Physical Broadcast Channel (PBCH).

[0017] Apply HARQ (Hybrid ARQ)-based retransmission control to the Downlink Shared Channel (DL-SCH). The DL-SCH can broadcast over the entire coverage area of a base station (cell). The DL-SCH supports dynamic or semi-static resource allocation. Semi-static resource allocation is also referred to as Persistent Scheduling. The DL-SCH supports discontinuous reception (DRX) of a communication terminal in order to reduce the power consumption of the communication terminal. The DL-SCH is mapped to the Physical Downlink Shared Channel (PDSCH).

[0018] The Paging Channel (PCH) supports DRX of a communication terminal in order to reduce the power consumption of the communication terminal. The PCH is required to broadcast over the entire coverage area of a base station (cell). The PCH is mapped to a physical resource such as the Physical Downlink Shared Channel (PDSCH) that can be dynamically utilized for traffic.

[0019] The Multicast Channel (MCH) is used to broadcast over the entire coverage area of a base station (cell). The MCH supports SFN synthesis of MBMS (Multimedia Broadcast Multicast Service) services (MTCH and MCCH) in multi-cell transmission. The MCH supports semi-static resource allocation. The MCH is mapped to the PMCH.

[0020] Apply HARQ (Hybrid ARQ)-based retransmission control to the Uplink Shared Channel (UL-SCH) in the uplink transmission channel. The UL-SCH supports dynamic or semi-static resource allocation. The UL-SCH is mapped to the Physical Uplink Shared Channel (PUSCH).

[0021] The Random Access Channel (RACH) is restricted to control information. There is a risk of collision in the RACH. The RACH is mapped to the Physical Random Access Channel (PRACH).

[0022] Describe Hybrid Automatic Repeat reQuest (HARQ). HARQ is a technology that improves the communication quality of a transmission line by combining Automatic Repeat reQuest (ARQ) and Forward Error Correction. HARQ has the following advantages: Even for a transmission line with changing communication quality, retransmission can be used to effectively utilize error correction. In particular, when retransmitting, the quality can be further improved by combining the reception results of the initial transmission and the retransmission.

[0023] Describe an example of a retransmission method. When the receiving side cannot correctly decode the received data, in other words, when a Cyclic Redundancy Check (CRC) error occurs (CRC = NG), "Nack" is sent from the receiving side to the sending side. The sending side that receives "Nack" retransmits the data. When the receiving side can correctly decode the received data, in other words, when no CRC error occurs (CRC = OK), "Ack" is sent from the receiving side to the sending side. The sending side that receives "Ack" sends the next data.

[0024] Describe the Logical Channel described in Non-Patent Document 1 (Chapter 6). The Broadcast Control Channel (BCCH) is a downlink channel for broadcasting system control information. The BCCH as a logical channel is mapped to the Broadcast Channel (BCH) or the Downlink Shared Channel (DL-SCH) as a transport channel.

[0025] The Paging Control Channel (PCCH) is a downlink channel for sending paging information and changes in system information. The PCCH is used when the network does not know the cell location of the communication terminal. The PCCH as a logical channel is mapped to the Paging Channel (PCH) as a transport channel.

[0026] The Common Control Channel (CCCH) is a channel for sending control information between a communication terminal and a base station. The CCCH is used when there is no Radio Resource Control (RRC) connection between the communication terminal and the network. In the downlink direction, the CCCH is mapped to the Downlink Shared Channel (DL-SCH) as a transport channel. In the uplink direction, the CCCH is mapped to the Uplink Shared Channel (UL-SCH) as a transport channel.

[0027] The Multicast Control Channel (MCCH) is a downlink channel for point-to-multipoint transmission. The MCCH is used to send MBMS control information for one or several MTCHs from the network to the communication terminal. The MCCH is only used for the communication terminal during the MBMS reception process. The MCCH is mapped to the Multicast Channel (MCH) which is a transport channel.

[0028] The Dedicated Control Channel (DCCH) is a channel for sending dedicated control information between the communication terminal and the network in a point-to-point manner. The DCCH is used when the communication terminal has an RRC connection. In the uplink, the DCCH is mapped to the Uplink Shared Channel (UL-SCH), and in the downlink, it is mapped to the Downlink Shared Channel (DL-SCH).

[0029] The Dedicated Traffic Channel (DTCH) is a channel for point-to-point communication for sending user information to a dedicated communication terminal. The DTCH exists in both the uplink and the downlink. In the uplink, the DTCH is mapped to the Uplink Shared Channel (UL-SCH), and in the downlink, it is mapped to the Downlink Shared Channel (DL-SCH).

[0030] The Multicast Traffic Channel (MTCH) is a downlink channel for sending traffic data from the network to the communication terminal. The MTCH is a channel only used for the communication terminal during the MBMS reception process. The MTCH is mapped to the Multicast Channel (MCH).

[0031] CGI refers to the Cell Global Identifier. ECGI refers to the E-UTRAN Cell Global Identifier. In LTE, the later-mentioned LTE-A (Long Term Evolution - Advanced), and UMTS (Universal Mobile Telecommunication System), Closed Subscriber Group (CSG) cells are introduced.

[0032] A CSG (Closed Subscriber Group) cell is a cell for which the operator determines the subscribers with the right of use (hereinafter sometimes referred to as “cell for specific subscribers”). The determined subscribers are permitted to access one or more cells of a PLMN (Public Land Mobile Network). One or more cells permitted for the determined subscribers to access are referred to as “CSG cell(s)”. However, there are access restrictions in the PLMN.

[0033] A CSG cell is a part of a PLMN that broadcasts an inherent CSG identity (CSG ID) and broadcasts “TRUE” using a CSG Indication. Members of a subscriber group that have been pre-registered for use and are permitted access the CSG cell using the CSG ID in the access permission information.

[0034] The CSG ID is broadcast by a CSG cell or a cell. There are multiple CSG IDs in an LTE-based communication system. Also, for the convenience of access by CSG-associated members, the CSG ID is used by a communication terminal (UE).

[0035] Location tracking of a communication terminal is performed in units of an area composed of one or more cells. Location tracking is to track the location of the communication terminal even in the standby state so as to call the communication terminal, in other words, it is performed to be able to call the communication terminal. The area used for location tracking of this communication terminal is called a tracking area.

[0036] In 3GPP, base stations called Home-NodeB (Home-NB; HNB) and Home-eNodeB (Home-eNB; HeNB) have been studied. HNBs in UTRAN and HeNBs in E-UTRAN are, for example, base stations for access services for home, corporate, and commercial use. Three different access modes for HeNBs and HNBs are disclosed in Non-Patent Document 2. Specifically, an Open access mode, a Closed access mode, and a Hybrid access mode are disclosed.

[0037] Furthermore, in 3GPP, as Release 10, the standardization of Long Term Evolution Advanced (LTE-A) is continuously progressing (see Non-Patent Documents 3 and 4). LTE-A is based on the radio access mode of LTE and is constituted by adding some new technologies thereto.

[0038] In the LTE-A system, in order to support wider transmission bandwidths of up to 100 MHz, carrier aggregation (CA) that aggregates two or more component carriers (CC) (also referred to as "aggregation") has been studied. CA is described in Non-Patent Document 1.

[0039] When CA is configured, the UE has a unique RRC connection with the network (NW). In the RRC connection, one serving cell provides NAS mobility information and security input. This cell is called the primary cell (PCell). In the downlink, the carrier corresponding to the PCell is the downlink primary component carrier (DL PCC). In the uplink, the carrier corresponding to the PCell is the uplink primary component carrier (UL PCC).

[0040] According to the UE's capability, secondary cells (SCells) are configured to form a group of serving cells together with the PCell. In the downlink, the carrier corresponding to the SCell is the downlink secondary component carrier (DL SCC). In the uplink, the carrier corresponding to the SCell is the uplink secondary component carrier (UL SCC).

[0041] For one UE, a group of serving cells composed of one PCell and one or more SCells is configured.

[0042] In addition, as new technologies of LTE-A, there are technologies for supporting wider bandwidths (Wider bandwidth extension) and coordinated multiple point transmission and reception (CoMP) technologies, etc. CoMP studied for implementing LTE-A in 3GPP is described in Non-Patent Document 1.

[0043] In addition, in 3GPP, in order to cope with the huge future traffic volume, research is being conducted on the use of small eNBs (hereinafter sometimes referred to as "small-scale base station devices") that form small cell areas. For example, research is being conducted on technologies such as: by setting up multiple small eNBs and forming multiple small cell areas to improve frequency utilization efficiency and achieve an increase in communication capacity. Specifically, there is Dual Connectivity (DC) where a UE is connected to two eNBs for communication. DC is described in Non-Patent Document 1.

[0044] Sometimes one of the eNBs performing Dual Connectivity (DC) is called the "Master eNB (abbreviation: MeNB)", and the other is called the "Secondary eNB (abbreviation: SeNB)".

[0045] There is a trend of increasing traffic volume in mobile networks, and the communication speed is also continuously developing towards high speed. If LTE and LTE-A are officially put into use, it can be foreseen that the communication speed will further accelerate.

[0046] In addition, a fifth-generation (hereinafter sometimes denoted as "5G") radio access system aiming to start serving the next-generation mobile communication after 2020 is under research. For example, in Europe, an organization called METIS is summarizing the requirements for 5G (refer to Non-Patent Document 5).

[0047] In the 5G radio access system, for the LTE system, it is assumed that the system capacity is 1000 times, the data transfer speed is 100 times, the data processing delay is 1 / 10, and the simultaneous connection number of communication terminals is 100 times. The cases of achieving further low power consumption and low cost of devices can be cited as necessary conditions.

[0048] To meet such requirements, in 3GPP, as Release 14, the discussion of the 5G standard is continuously advancing (refer to Non-Patent Documents 6 and 7). The technology in the radio section of 5G is called "New Radio (abbreviation: NR) Access Technology: new radio access technology", and some new technologies are under discussion (refer to Non-Patent Documents 8 to 11). For example, the frame structure for NR using self-contained subframes and precoding using uplink sounding reference signals (SRS) have been discussed.

[0049] Prior Art Documents

[0050] Non-Patent Documents

[0051] Non-Patent Document 1: 3GPP TS 36.300 V13.4.0

[0052] Non-Patent Document 2: 3GPP S1-083461

[0053] Non-Patent Document 3: 3GPP TR 36.814 V9.0.0

[0054] Non-Patent Document 4: 3GPP TR 36.912 V13.0.0

[0055] Non-Patent Document 5: “Scenarios, requirements and KPIs for 5G mobile and wireless system”, [online], April 30, 2013 (Heisei 25), ICT-317669-METIS / D1.1, [searched on September 16, 2016], Internet <https: / / www.metis2020.com / documents / deliverables / >

[0056] Non-Patent Document 6: 3GPP TR 23.799 V0.7.0

[0057] Non-Patent Document 7: 3GPP TR 38.912 V0.0.1

[0058] Non-Patent Document 8: 3GPP RP-160697

[0059] Non-Patent Document 9: 3GPP R1-164032

[0060] Non-Patent Document 10: 3GPP R1-165887

[0061] Non-Patent Document 11: 3GPP R1-166880 Summary of the Invention

[0062] Technical Problem to be Solved by the Invention

[0063] In 5G, for the LTE system, performance requirements such as a 100-fold increase in data transmission speed and a tenth of the data processing delay are required.

[0064] In order to reduce the latency, as the frame structure for NR, a self-contained subframe that constitutes an uplink and a downlink in one subframe and returns a response to the downlink in the same subframe is proposed (see Non-Patent Document 9).

[0065] In a self - contained sub - frame, there is an interval (hereinafter, sometimes referred to as "interval" or "Gap") used by the UE for demodulating and decoding a downlink signal, generating a pre - uplink - coding signal, and encoding and modulating an uplink signal during the transition from the downlink to the uplink.

[0066] In addition, in a self - contained sub - frame, for the PUCCH from the UE, especially for the Nack signal, it is advocated that the eNB re - transmits to the UE in the next sub - frame. Therefore, for example, in the above - mentioned Non - Patent Document 11, it is advocated to set an interval for the eNB to demodulate and decode the PUCCH, generate a re - transmission signal, and encode and modulate the re - transmission signal after the transmission of the uplink signal from the UE.

[0067] Therefore, in the case of using a self - contained sub - frame, the above - mentioned interval is wasted, and the resource utilization efficiency decreases. In addition, due to the setting of the above - mentioned interval, the number of symbols that can be allocated to the uplink signal becomes smaller. As a result, the transmission timing of uplink control signals such as Ack / Nack overlaps with the transmission timing of SRS, and the transmission frequency of SRS decreases. Therefore, the precoding performance deteriorates, and thus, there is a problem of a decrease in the transmission speed.

[0068] An object of the present invention is to provide a communication system capable of suppressing a decrease in the transmission speed.

[0069] Technical solution for solving the technical problem

[0070] The communication system of the present invention is a communication system including a base - station device and a communication terminal device capable of wireless communication with the base - station device, characterized in that the base - station device and the communication terminal device communicate using a self - contained sub - frame, and the self - contained sub - frame includes: a downlink signal transmitted from the base - station device to the communication terminal device; and an uplink signal transmitted from the communication terminal device to the base - station device in response to the downlink signal, and the uplink signal is configured to include: an uplink control signal representing information for controlling the transmission of the uplink signal; and uplink user data transmitted before and after the uplink control signal, and the base - station device notifies the communication terminal device of the structure of the uplink signal.

[0071] Advantages of the invention

[0072] According to the communication system of the present invention, the base - station device and the communication terminal device communicate using a self - contained sub - frame including a downlink signal and an uplink signal. The structure of the uplink signal is notified from the base - station device to the communication terminal device. Thus, the communication terminal device can recognize the structure of the uplink signal in the self - contained sub - frame, and therefore, can use the self - contained sub - frame to transmit the uplink signal.

[0073] The uplink signal is configured to include an uplink control signal and uplink user data transmitted before and after the uplink control signal. Therefore, the interval period between the downlink signal and the uplink signal, during which neither the uplink signal nor the downlink signal is transmitted, can be reduced. In addition, by omitting or reducing the interval period after the transmission of the uplink signal, the retransmission of the downlink signal in the next self - contained subframe can be performed. Therefore, radio resources can be used efficiently. Accordingly, a decrease in the transmission speed in the case of using self - contained subframes can be suppressed.

[0074] The objects, features, aspects, and advantages of the present invention will become more apparent from the following detailed description and the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0075] Figure 1 It is an explanatory diagram showing the structure of a radio frame used in a communication system of the LTE system.

[0076] Figure 2 It is a block diagram showing the overall structure of a communication system 200 of the LTE system being studied in 3GPP.

[0077] Figure 3 It is a block diagram showing the structure of a communication terminal according to the present invention, namely Figure 2 the mobile terminal 202 shown.

[0078] Figure 4 It is a block diagram showing the structure of a base station according to the present invention, namely Figure 2 the base station 203 shown.

[0079] Figure 5 It is a block diagram showing the structure of the MME according to the present invention.

[0080] Figure 6 It is a flowchart showing an outline from cell search to standby operation performed by a communication terminal (UE) in a communication system of the LTE system.

[0081] Figure 7 It is a diagram showing the concept of a cell structure when a macro eNB and a small eNB are mixed.

[0082] Figure 8 It is a diagram showing an example of a process related to the setting of the interval length after the transmission of an uplink signal in a self - contained subframe.

[0083] Figure 9 It is a diagram showing an example of the uplink signal structure in a self - contained subframe.

[0084] Figure 10It is a diagram showing an example of a process related to setting the uplink signal structure in a self - contained subframe.

[0085] Figure 11 It is a diagram showing an example of a method for performing scheduling one frame ahead in Modification Example 2 of Embodiment 1.

[0086] Figure 12 It is a diagram showing an example of a method for performing scheduling one frame ahead in Modification Example 2 of Embodiment 1.

[0087] Figure 13 It is a diagram showing an example of a method for performing re - transmission scheduling two frames ahead in Modification Example 2 of Embodiment 1.

[0088] Figure 14 It is a diagram showing an example of a method for performing re - transmission scheduling two frames ahead in Modification Example 2 of Embodiment 1.

[0089] Figure 15 It is a diagram showing an example of a method for performing scheduling for initial transmission and re - transmission two frames ahead in Modification Example 2 of Embodiment 1.

[0090] Figure 16 It is a diagram showing an example of a method for performing scheduling for initial transmission and re - transmission two frames ahead in Modification Example 2 of Embodiment 1.

[0091] Figure 17 It is a diagram showing an example of a method for performing scheduling one frame ahead in the case of performing one re - transmission in Modification Example 3 of Embodiment 1.

[0092] Figure 18 It is a diagram showing an example of a method for performing scheduling one frame ahead in the case of performing one re - transmission in Modification Example 3 of Embodiment 1.

[0093] Figure 19 It is a diagram showing an example of a method for performing re - transmission scheduling two frames ahead in the case of performing one re - transmission in Modification Example 3 of Embodiment 1.

[0094] Figure 20 It is a diagram showing an example of a method for performing re - transmission scheduling two frames ahead in the case of performing one re - transmission in Modification Example 3 of Embodiment 1.

[0095] Figure 21 It is a diagram showing an example of a method for performing scheduling for initial transmission and re - transmission two frames ahead in the case of performing one re - transmission in Modification Example 3 of Embodiment 1.

[0096] Figure 22It is a diagram showing an example of a method for scheduling the first transmission and retransmission two frames before in the case of performing one retransmission in Modification 3 of Embodiment 1.

[0097] Figure 23 It is a diagram showing an example of a method for scheduling one frame before in Modification 4 of Embodiment 1.

[0098] Figure 24 It is a diagram showing an example of a method for scheduling one frame before in Modification 4 of Embodiment 1.

[0099] Figure 25 It is a diagram showing an example of a method for scheduling one frame before in the case of performing one retransmission in Modification 4 of Embodiment 1.

[0100] Figure 26 It is a diagram showing an example of a method for scheduling one frame before in the case of performing one retransmission in Modification 4 of Embodiment 1.

[0101] Figure 27 It is a diagram showing an example of a method for scheduling one frame before in Modification 5 of Embodiment 1.

[0102] Figure 28 It is a diagram showing an example of a method for scheduling one frame before in Modification 5 of Embodiment 1.

[0103] Figure 29 It is a diagram showing an example of a method for scheduling one frame before in the case of performing one retransmission in Modification 5 of Embodiment 1.

[0104] Figure 30 It is a diagram showing an example of a method for scheduling one frame before in the case of performing one retransmission in Modification 5 of Embodiment 1.

[0105] Figure 31 It is a diagram showing an example of a method for scheduling one frame before in Modification 6 of Embodiment 1.

[0106] Figure 32 It is a diagram showing an example of a method for scheduling one frame before in Modification 6 of Embodiment 1.

[0107] Figure 33 It is a diagram showing an example of a method for scheduling one frame before in the case of performing one retransmission in Modification 6 of Embodiment 1.

[0108] Figure 34 It is a diagram showing an example of a method for scheduling one frame before in the case of performing one retransmission in Modification 6 of Embodiment 1.

[0109] Figure 35 This is a diagram showing an example of a method for scheduling one frame ahead in Variation 7 of Embodiment 1.

[0110] Figure 36 This is a diagram showing an example of a method for scheduling one frame ahead in Variation 7 of Embodiment 1.

[0111] Figure 37 This is a diagram showing an example of a method for scheduling one frame ahead in the case of performing one retransmission in Variation 7 of Embodiment 1.

[0112] Figure 38 This is a diagram showing an example of a method for scheduling one frame ahead in the case of performing one retransmission in Variation 7 of Embodiment 1.

[0113] Figure 39 This is a diagram for explaining a method for setting the SRS transmission period in Embodiment 2.

[0114] Figure 40 This is a diagram for explaining a method for transmitting periodic SRS in the case where an SRS transmission offset is set together with the SRS transmission period.

[0115] Figure 41 This is a diagram for explaining a method for transmitting periodic SRS in the case where an SRS transmission offset is set together with the SRS transmission period.

[0116] Figure 42 This is a diagram for explaining a method for transmitting periodic SRS in the case where an SRS transmission offset is set together with the SRS transmission period.

[0117] Figure 43 This is a diagram showing an example of a process for setting the SRS transmission period in Embodiment 2.

[0118] Figure 44 This is a diagram showing an example of an SRS transmission process in the case where multiple subframes capable of performing SRS transmission are configured.

[0119] Figure 45 This is a diagram showing an example of an SRS transmission process in the case where multiple subframes capable of performing SRS transmission are configured and the SRS subframe structure is changed.

[0120] Figure 46 This is a diagram showing an example of an SRS transmission process in the case where multiple subframes capable of performing SRS transmission are configured and the SRS subframe structure is changed.

[0121] Figure 47This is a diagram showing an example of the process in which a UE transmits SRS period change request information in Variant 2 of Embodiment 2.

[0122] Figure 48 This is a diagram for explaining a case where there is a conflict between the transmission timing of Ack / Nack and SRS in LTE.

[0123] Figure 49 This is a diagram showing an example of a case where an uplink control signal and SRS in Embodiment 3 are frequency-division multiplexed and transmitted on the same symbol.

[0124] Figure 50 This is a diagram showing another example of a case where an uplink control signal and SRS in Embodiment 3 are frequency-division multiplexed and transmitted on the same symbol.

[0125] Figure 51 This is a diagram showing yet another example of a case where an uplink control signal and SRS in Embodiment 3 are frequency-division multiplexed and transmitted on the same symbol.

[0126] Figure 52 This is a diagram showing an example of a case where the number of UL symbols is increased by one symbol and Ack / Nack and SRS are time-division multiplexed.

[0127] Figure 53 This is a diagram showing another example of a case where the number of UL symbols is increased by one symbol and Ack / Nack and SRS are time-division multiplexed.

[0128] Figure 54 This is a diagram for explaining an uplink signal from a UE in a case where an eNB is configured with multiple TRPs.

[0129] Figure 55 This is a diagram for explaining the reception timing in a TRP of an uplink signal transmitted from UE1.

[0130] Figure 56 This is a diagram for explaining the reception timing in a TRP of an uplink signal transmitted from UE1 when an adjustment value α is set.

[0131] Figure 57 This is a diagram showing a structural example of an uplink signal.

[0132] Figure 58 This is a diagram showing an example of the process for setting an adjustment value for uplink transmission timing in Embodiment 4.

[0133] Figure 59 This is a diagram showing an example of the process for setting an adjustment value for uplink transmission timing in Embodiment 4.

[0134] Figure 60 This is a diagram showing an example of the process for setting the adjustment value of the uplink transmission timing in Embodiment 4.

[0135] Figure 61 This is a diagram for explaining the reception timing at the TRP in the case where an adjustment value β is set for an uplink signal with a gCP transmitted from UE1 attached.

[0136] Figure 62 This is a diagram showing an example of setting a part of a continuous uplink signal as a gCP.

[0137] Figure 63 This is a diagram showing another example of setting a part of a continuous uplink signal as a gCP.

[0138] Figure 64 This is a diagram for explaining the reception timing at the TRP of an uplink signal transmitted from UE1 in the case where an adjustment value γ is set in a structure with a GT set. Detailed Embodiments

[0139] Embodiment 1.

[0140] Figure 2 This is a block diagram showing the overall structure of a communication system 200 of the LTE mode being explored in 3GPP. Figure 2 An explanation will be given. The radio access network is referred to as E-UTRAN (Evolved Universal Terrestrial Radio Access Network). A communication terminal device, that is, a mobile terminal device (hereinafter referred to as “mobile terminal (User Equipment: UE)”) 202 can perform wireless communication with a base station device (hereinafter referred to as “base station (E-UTRAN NodeB: eNB)”) 203 and perform signal transmission and reception using wireless communication.

[0141] Here, the “communication terminal device” refers not only to mobile terminal devices such as mobile phone terminal devices that can move, but also includes devices that do not move such as sensors. In the following description, the “communication terminal device” may sometimes be abbreviated as “communication terminal”.

[0142] If the control protocols for the mobile terminal 202, such as RRC (Radio Resource Management), and the user plane, such as PDCP (Packet Data Convergence Protocol), RLC (Radio Link Control), MAC (Medium Access Control), and PHY (Physical layer), terminate at the base station 203, then the E-UTRAN consists of one or more base stations 203.

[0143] The control protocol RRC (Radio Resource Control) between the mobile terminal 202 and the base station 203 performs functions such as Broadcast, Paging, and RRC connection management. The states of the base station 203 and the mobile terminal 202 in RRC are RRC_IDLE and RRC_CONNECTED.

[0144] In the RRC_IDLE state, PLMN (Public Land Mobile Network) selection, broadcast of System Information (SI), Paging, cell re-selection, mobility, etc. are performed. In the RRC_CONNECTED state, the mobile terminal has an RRC connection and can send and receive data with the network. In addition, in the RRC_CONNECTED state, Handover (HO), measurement of Neighbour cells, etc. are also performed.

[0145] The base station 203 is classified into eNB207 and Home-eNB206. The communication system 200 includes an eNB group 203-1 containing multiple eNB207 and a Home-eNB group 203-2 containing multiple Home-eNB206. Also, the system composed of the EPC (Evolved Packet Core) as the core network and the E-UTRAN 201 as the radio access network is called the EPS (Evolved Packet System). Sometimes the EPC as the core network and the E-UTRAN 201 as the radio access network are collectively referred to as the "network".

[0146] The eNB 207 is connected to a Mobility Management Entity (MME), a Serving Gateway (S-GW), or an MME / S-GW unit (hereinafter sometimes referred to as the "MME unit") 204 including the MME and the S-GW via the S1 interface, and communicates control information between the eNB 207 and the MME unit 204. For one eNB 207, multiple MME units 204 may be connected. The eNBs 207 are connected to each other via the X2 interface and communicate control information therebetween.

[0147] The Home-eNB 206 is connected to the MME unit 204 via the S1 interface and communicates control information between the Home-eNB 206 and the MME unit 204. Multiple Home-eNBs 206 are connected to one MME unit 204. Alternatively, the Home-eNB 206 is connected to the MME unit 204 via a Home-eNB GateWay (HeNBGW) 205. The Home-eNB 206 and the HeNBGW 205 are connected via the S1 interface, and the HeNBGW 205 and the MME unit 204 are connected via the S1 interface.

[0148] One or more Home-eNBs 206 are connected to one HeNBGW 205 and communicate information via the S1 interface. The HeNBGW 205 is connected to one or more MME units 204 and communicates information via the S1 interface.

[0149] The MME unit 204 and the HeNBGW 205 are upper-level devices, specifically upper-level nodes, which control the connections between the eNB 207 and the Home-eNB 206, which are base stations, and the mobile terminal (UE) 202. The MME unit 204 constitutes the Evolved Packet Core (EPC) as the core network. The base station 203 and the HeNBGW 205 constitute the Evolved Universal Terrestrial Radio Access Network (E-UTRAN) 201.

[0150] Moreover, in 3GPP, the following structure has been studied. An X2 interface between Home-eNBs 206 is supported. That is, the Home-eNBs 206 are connected to each other via the X2 interface and communicate control information therebetween. From the perspective of the MME unit 204, the HeNBGW 205 can be regarded as a Home-eNB 206. From the perspective of the Home-eNB 206, the HeNBGW 205 can be regarded as the MME unit 204.

[0151] Whether Home-eNB 206 is connected to the MME unit 204 via the HeNB GW 205 or directly connected to the MME unit 204, the interface between Home-eNB 206 and the MME unit 204 is the S1 interface in the same way.

[0152] The base station 203 can form one cell or multiple cells. Each cell has a predetermined range as the coverage range within which communication with the mobile terminal 202 can be performed, and wireless communication is performed with the mobile terminal 202 within the coverage range. In the case where one base station 203 forms multiple cells, each cell is configured to be able to communicate with the mobile terminal 202.

[0153] Figure 3 It represents the communication terminal related to the present invention, that is, Figure 2 a block diagram showing the structure of the mobile terminal 202 shown. The Figure 3 transmission processing of the mobile terminal 202 shown will be described. First, the control data from the protocol processing unit 301 and the user data from the application unit 302 are saved in the transmission data buffer unit 303. The data saved in the transmission data buffer unit 303 is transmitted to the encoder unit 304 to perform encoding processing such as error correction. There may also be data that is directly output from the transmission data buffer unit 303 to the modulation unit 305 without performing encoding processing. The data after the encoding processing is performed by the encoding unit 304 is subjected to modulation processing in the modulation unit 305. The modulated data is converted into a baseband signal and then output to the frequency conversion unit 306, where it is converted into a radio transmission frequency. After that, the transmission signal is transmitted from the antenna 307 to the base station 203.

[0154] In addition, the reception processing of the mobile terminal 202 is performed as follows. The radio signal from the base station 203 is received by the antenna 307. The received signal is converted from the radio reception frequency to a baseband signal by the frequency conversion unit 306 and is subjected to demodulation processing in the demodulation unit 308. The demodulated data is transmitted to the decoding unit 309 to perform decoding processing such as error correction. Among the decoded data, the control data is transmitted to the protocol processing unit 301, and the user data is transmitted to the application unit 302. A series of processes of the mobile terminal 202 are controlled by the control unit 310. Thus, although it is omitted in Figure 3 , the control unit 310 is connected to each unit 301 to 309.

[0155] Figure 4 It is a block diagram showing the structure of the base station related to the present invention, that is, Figure 2 the base station 203 shown. The Figure 4A description will be given of the transmission processing of the base station 203 shown. The EPC communication unit 401 performs data transmission and reception between the base station 203 and the EPC (such as the MME unit 204), the HeNB GW 205, etc. The other base station communication unit 402 performs data transmission and reception with other base stations. The EPC communication unit 401 and the other base station communication unit 402 exchange information with the protocol processing unit 403 respectively. The control data from the protocol processing unit 403, and the user data and control data from the EPC communication unit 401 and the other base station communication unit 402 are stored in the transmission data buffer unit 404.

[0156] The data stored in the transmission data buffer unit 404 is transmitted to the encoder unit 405 to perform encoding processing such as error correction. There may also be data that is directly output from the transmission data buffer unit 404 to the modulation unit 406 without performing encoding processing. The encoded data is subjected to modulation processing in the modulation unit 406. The modulated data is converted into a baseband signal and then output to the frequency conversion unit 407, where it is converted into a radio transmission frequency. Thereafter, using the antenna 408, the transmission signal is transmitted to one or more mobile terminals 202.

[0157] In addition, the reception processing of the base station 203 is performed as follows. The radio signal from one or more mobile terminals 202 is received by the antenna 408. The received signal is converted from the radio reception frequency to a baseband signal by the frequency conversion unit 407 and is subjected to demodulation processing in the demodulation unit 409. The demodulated data is transmitted to the decoding unit 410 to perform decoding processing such as error correction. Among the decoded data, the control data is transmitted to the protocol processing unit 403, or the EPC communication unit 401, the other base station communication unit 402, and the user data is transmitted to the EPC communication unit 401 and the other base station communication unit 402. A series of processing of the base station 203 is controlled by the control unit 411. Thus, although it is omitted in Figure 4 the control unit 411 is connected to each of the units 401 to 410.

[0158] Figure 5 is a block diagram showing the structure of the MME according to the present invention. Figure 5 In, the above is shown Figure 2The structure of the MME 204a included in the MME unit 204 shown. The PDN GW communication unit 501 performs data transmission and reception between the MME 204a and the PDN GW. The base station communication unit 502 performs data transmission and reception via the S1 interface between the MME 204a and the base station 203. When the data received from the PDN GW is user data, the user data is transmitted from the PDN GW communication unit 501 via the user plane communication unit 503 to the base station communication unit 502 and is sent to one or more base stations 203. When the data received from the base station 203 is user data, the user data is transmitted from the base station communication unit 502 via the user plane communication unit 503 to the PDN GW communication unit 501 and is sent to the PDN GW.

[0159] When the data received from the PDN GW is control data, the control data is transmitted from the PDN GW communication unit 501 to the control plane control unit 505. When the data received from the base station 203 is control data, the control data is transmitted from the base station communication unit 502 to the control plane control unit 505.

[0160] When the HeNBGW 205 exists, the HeNBGW communication unit 504 is set, and data transmission and reception via the interface (IF) between the MME 204a and the HeNBGW 205 are performed according to the information type. The control data received from the HeNBGW communication unit 504 is transmitted from the HeNBGW communication unit 504 to the control plane control unit 505. The processing result in the control plane control unit 505 is sent to the PDN GW via the PDN GW communication unit 501. In addition, the result processed by the control plane control unit 505 is sent to one or more base stations 203 via the base station communication unit 502 and through the S1 interface, or is sent to one or more HeNBGWs 205 via the HeNBGW communication unit 504.

[0161] The control plane control unit 505 includes a NAS security unit 505-1, an SAE bearer control unit 505-2, an idle state mobility management unit 505-3, etc., and performs all processing for the control plane. The NAS security unit 505-1 provides the security of NAS (Non-Access Stratum) messages, etc. The SAE bearer control unit 505-2 manages the bearers of SAE (System Architecture Evolution), etc. The idle state mobility management unit 505-3 performs mobility management in the standby state (idle state; LTE-IDLE state, or simply called idle), generates and controls paging signals in the standby state, adds, deletes, updates, retrieves, and manages the tracking areas of one or more mobile terminals 202 within the coverage area, etc.

[0162] The MME 204a distributes paging signals to one or more base stations 203. In addition, the MME 204a performs mobility control in the standby state (Idle State). The MME 204a manages the tracking area list when the mobile terminal is in the standby state and in the active state (Active State). The MME 204a starts the paging protocol by sending a paging message to the cells belonging to the tracking area (Tracking Area) registered (registered: registered) by the UE. The management of the CSG of the Home-eNB 206 connected to the MME 204a, the management of the CSG ID, and the white list management can be performed by the idle state mobility management unit 505-3.

[0163] Next, an example of a cell search method in the communication system is shown. Figure 6 It is a flowchart showing an overview from cell search to standby operation performed by a communication terminal (UE) in an LTE-based communication system. If the communication terminal starts cell search, in step ST601, it uses the first synchronization signal (P-SS) and the second synchronization signal (S-SS) sent from the surrounding base stations to obtain synchronization of the time slot timing and frame timing.

[0164] The P-SS and S-SS are collectively referred to as the synchronization signal (Synchronization Signal: SS). Synchronization codes corresponding one-to-one to the PCI assigned to each cell are allocated in the synchronization signal (SS). It is considered to set the number of PCI to 504. Synchronization is obtained using these 504 PCI, and the PCI of the cell for which synchronization is obtained is detected (determined).

[0165] Next, in step ST602, the cell-specific reference signal (CRS), which is the reference signal (RS) sent from the base station to each cell for which synchronization has been obtained, is detected, and the received power of the RS (Reference Signal Received Power: RSRP) is measured. The reference signal (RS) uses a coding that corresponds one-to-one with the PCI. The correlation can be obtained using this coding to separate from other cells. By deriving the coding for the RS of this cell based on the PCI determined in step ST601, the RS can be detected and the received power of the RS can be measured.

[0166] Next, in step ST603, the cell with the best reception quality of the RS is selected from the one or more cells detected up to step ST602. For example, the cell with the highest received power of the RS, i.e., the best cell, is selected.

[0167] Next, in step ST604, the PBCH of the best cell is received to obtain the broadcast information, i.e., the BCCH. The BCCH on the PBCH maps the MIB (Master Information Block) that contains cell structure information. Therefore, by receiving the PBCH and obtaining the BCCH, the MIB can be obtained. As information in the MIB, for example, there are the DL (downlink) system bandwidth (also referred to as the transmission bandwidth configuration: dl-bandwidth), the number of transmit antennas, the SFN (System Frame Number), etc.

[0168] Next, in step ST605, based on the cell structure information in the MIB, the DL-SCH of this cell is received, and the SIB (System Information Block) 1 in the broadcast information BCCH is obtained. SIB1 contains information related to accessing this cell, information related to cell selection, and scheduling information for other SIBs (SIBk; k is an integer greater than or equal to 2). In addition, SIB1 also contains the Tracking Area Code (TAC).

[0169] Next, in step ST606, the communication terminal compares the TAC of SIB1 received in step ST605 with the TAC part of the tracking area identity (TAI) in the tracking area list already stored in the communication terminal. The tracking area list is also referred to as the TAI list. TAI is identification information used to identify a tracking area and consists of an MCC (Mobile Country Code), an MNC (Mobile Network Code), and a TAC (Tracking Area Code). The MCC is the country code. The MNC is the network code. The TAC is the code number of the tracking area.

[0170] If the result of the comparison in step S606 is that the TAC received in step ST605 is the same as the TAC included in the tracking area list, the communication terminal enters the standby operation in this cell. When comparing, if the TAC received in step ST605 is not included in the tracking area list, the communication terminal passes through this cell and requests the core network (Core Network, EPC) including the MME, etc. to change the tracking area to perform a TAU (Tracking Area Update).

[0171] The device constituting the core network (hereinafter sometimes referred to as the "core network side device") updates the tracking area list based on the TAU request signal and the identification number (UE-ID, etc.) of the communication terminal sent from the communication terminal. The core network side device sends the updated tracking area list to the communication terminal. The communication terminal rewrites (updates) the TAC list stored in the communication terminal based on the received tracking area list. Thereafter, the communication terminal enters the standby operation in this cell.

[0172] Due to the popularization of smartphones and tablet terminal devices, the traffic volume using cellular system wireless communication has increased explosively, so there is a concern about the shortage of radio resources worldwide. To address this situation and improve the frequency utilization efficiency, research has been conducted on the miniaturization of cells and the promotion of spatial separation.

[0173] In the existing cell structure, the cell composed of eNBs has a relatively wide coverage area. In the past, cells were configured in such a way that a certain area was covered by using the relatively wide coverage areas of multiple cells composed of multiple eNBs.

[0174] In the case of cell miniaturization, the coverage area of a cell formed by an existing eNB is narrower compared to the coverage area of a cell formed by an existing eNB. Therefore, as in the prior art, in order to cover a certain area, a large number of eNBs after cell miniaturization are required compared to existing eNBs.

[0175] In the following description, a cell with a relatively large coverage area, such as a cell formed by a conventional eNB, is referred to as a "macro cell", and the eNB forming the macro cell is referred to as a "macro eNB". In addition, a cell with a relatively small coverage area, such as a cell after cell miniaturization, is referred to as a "small cell", and the eNB forming the small cell is referred to as a "small eNB".

[0176] The macro eNB can be, for example, the "Wide Area Base Station" described in Non-Patent Document 7.

[0177] The small eNB can be, for example, a low-power node, a local node, and a hot spot, etc. In addition, the small eNB can be a pico eNB forming a pico cell, a femto eNB forming a femto cell, a HeNB, an RRH (Remote Radio Head), an RRU (Remote Radio Unit), an RRE (Remote Radio Equipment), or an RN (Relay Node). In addition, the small eNB can also be the "Local Area Base Station" or "HomeBase Station" described in Non-Patent Document 7.

[0178] Figure 7 It is a diagram showing the concept of the cell structure when macro eNBs and small eNBs are mixed together. The macro cell formed by the macro eNB has a relatively large coverage area 701. The small cell formed by the small eNB has a coverage area 702 that is smaller than the coverage area 701 of the macro eNB (macro cell).

[0179] In the case where multiple eNBs are mixed together, the coverage area of a cell formed by a certain eNB may be included in the coverage area of a cell formed by other eNBs. Figure 7 In the cell structure shown, as indicated by reference numerals "704" or "705", the coverage area 702 of the small cell formed by the small eNB is sometimes included in the coverage area 701 of the macro cell formed by the macro eNB.

[0180] In addition, as indicated by reference numeral "705", there are cases where the coverage areas 702 of multiple, for example, two small cells are included within the coverage area 701 of one macro cell. A mobile terminal (UE) 703 is included within the coverage area 702 of a small cell, for example, and communicates via the small cell.

[0181] In addition, in Figure 7 the cell structure shown, as indicated by reference numeral "706", the following situation will occur, that is: the coverage area 701 of the macro cell constituted by the macro eNB and the coverage area 702 of the small cell constituted by the small eNB are complexly repeated.

[0182] In addition, as indicated by reference numeral "707", the following situation will also occur, that is: the coverage area 701 of the macro cell constituted by the macro eNB and the coverage area 702 of the small cell constituted by the small eNB do not overlap.

[0183] Moreover, as indicated by reference numeral "708", the following situation will also occur, that is: the coverage areas 702 of multiple small cells constituted by multiple small eNBs are formed within the coverage area 701 of one macro cell constituted by one macro eNB.

[0184] In LTE, in the downlink, adaptive scheduling is performed in an asynchronous manner, and in the uplink, adaptive or non - adaptive scheduling is used in a synchronous manner (refer to Non - Patent Document 1).

[0185] Here, symmetric scheduling means that the re - transmission timing is determined in advance according to the relative position with respect to the initial transmission timing. Asymmetric scheduling means that the re - transmission timing is not determined in advance, but the process number is included in the Downlink Control Information (DCI) and sent to the receiver to indicate the re - transmission timing.

[0186] In addition, in adaptive scheduling, the modulation and coding scheme (MCS) and frequency resource allocation can be changed at each re - transmission. In non - adaptive scheduling, the MCS and frequency resource allocation for re - transmission are the same as those for the initial transmission or the previous re - transmission, or are set to be changeable by a pre - determined method (refer to 3GPP TS36.321 V13.2.0 (hereinafter referred to as "Reference 1")).

[0187] In the self - contained sub - frames advocated in NR, the following structures are advocated: a structure mainly composed of downlink user data and Ack / Nack for the downlink user data, a structure mainly composed of uplink grants and uplink user data based on the uplink grants, a structure mainly composed of downlink reference signals and measurement results of the downlink reference signals, and a structure mainly composed of downlink control signals and CQI or sounding reference signal (SRS) based on the indication of the downlink control signals. In addition, symmetry between the downlink and the uplink is advocated, that is, a structure in which the time allocated to the downlink and the uplink is the same (refer to Non - Patent Document 9).

[0188] In addition, in the self - contained sub - frames, the following is advocated: an interval is also set for the part after the transmission of the uplink signal, so that the downlink re - transmission after receiving Nack can be transmitted in the next sub - frame, and the delay from the reception of Nack to the downlink re - transmission can be minimized (refer to Non - Patent Document 11).

[0189] However, in Non - Patent Document 11, a method for setting an interval for the sub - frame of the part after the transmission of the uplink signal is not disclosed. Therefore, the UE cannot recognize the sub - frame structure, and there is a problem that the reception of the downlink signal and the transmission of the uplink signal cannot be performed.

[0190] In this embodiment, a method for solving the above - mentioned problem is disclosed. In this embodiment, the eNB (in this specification, the base station of 5G is also called "eNB") sets an interval after the transmission of the uplink signal for the UE.

[0191] In the setting of the interval after the transmission of the uplink signal, for example, the length of the interval after the transmission of the uplink signal can be used. Regarding the method of providing the length of the interval of the uplink signal, for example, it can be provided in the smallest time unit in the 5G radio access system, it can be provided in symbol units, or it can be provided in other units. In addition, the length of the interval after the transmission of the uplink signal can also be provided as a ratio to the length of the sub - frame.

[0192] In addition, it can be set to select the length of the interval after the transmission of the uplink signal from several options. For example, a list of options and an identifier indicating which one is selected from the above list can be notified by the eNB to the UE. The list of options can be notified together with the above identifier, or can be notified separately.

[0193] In addition, a default value can be set for the interval length after the transmission of the uplink signal. As a situation where the default value is required, for example, when the UE is connected to the eNB. When the UE is connected to the eNB, it is necessary to receive broadcast information and paging signals. In addition, it is necessary to transmit a physical random access channel. At this time, the UE can communicate with the eNB through the subframe structure based on the above default value.

[0194] The above default value can be determined statically by a standard or can be set to be changeable.

[0195] The interval length after the transmission of the uplink signal can be provided as an absolute value, that is, the necessary length directly, or can also be provided as a relative value. As a reference when provided in a relative value manner, for example, the default value can be used, or it can be set to provide the difference from the previous setting value.

[0196] In addition, when setting the interval after the transmission of the uplink signal, it can be set so that the set interval length immediately becomes effective.

[0197] Alternatively, it can be notified when the set interval length becomes effective. In the above notification, for example, the moment when it becomes effective can be directly specified, or the time difference required from the notification moment to becoming effective can be specified. As the above moment, the subframe number can be used. In addition, as the above time difference, the number of subframes can be used. Thus, the change timing of the interval length can be shared between the eNB and the UE, and therefore, the transmission and reception loss between the eNB and the UE caused by the change of the interval setting can be prevented.

[0198] As specific examples of the method for notifying the setting of the interval after the transmission of the uplink signal, the following three (1) to (3) are disclosed.

[0199] (1) Semi-static setting.

[0200] (2) Dynamic setting.

[0201] (3) A combination of the above (1) and (2).

[0202] Regarding the semi-static setting of the above (1), for example, it can be broadcast by the eNB to the subordinate UEs. As an example of the broadcast, for example, RRC common signaling can be used. As an example of the RRC common signaling, for example, SIB1 or SIB2 can be used.

[0203] In addition, as another example of the quasi-static setting in the above (1), RRC dedicated signaling can be used. As RRC dedicated signaling, for example, RRC connection reconfiguration can be used. Alternatively, Message 4 in the random access process can also be used.

[0204] Regarding the dynamic setting in the above (2), for example, L1 / L2 signaling can be used. Thus, the interval setting can be changed for each Transmission Time Interval (TTI) or for each subframe, and therefore, the change of the interval setting within a shorter period can be performed.

[0205] In addition, as another example of the dynamic setting in the above (2), MAC signaling (MAC Control Element) can be used. Since MAC signaling controls retransmission, the setting can be notified with higher reliability.

[0206] Regarding the setting in the above (3), as one combination, the eNB can set different setting contents for the UE quasi-statically and dynamically respectively. For example, a list of options for the interval length can be provided quasi-statically, and an identifier indicating which one is selected can be provided dynamically. In addition, for example, the default value of the interval length can be notified quasi-statically, and the difference from the default value can be set dynamically. Thus, the flexible setting of the interval length after the transmission of the uplink signal can be performed with a smaller amount of signaling.

[0207] Regarding the setting of the interval after the transmission of the uplink signal, the eNB can notify the UE of the downlink signal, the interval between the downlink signal and the uplink signal, and the respective structure information of the uplink signal. The UE can calculate the interval length after the transmission of the uplink signal based on the above respective structure information. As a calculation method of the interval length after the transmission of the uplink signal, for example, the length obtained by subtracting the sum of the lengths of the downlink signal, the interval between the downlink signal and the uplink signal, and the uplink signal from the self-contained subframe length can be set as the interval length after the transmission of the uplink signal. The UE can use the above calculation result as the interval setting after the transmission of the uplink signal.

[0208] In addition, regarding the setting of the interval after the transmission of the uplink signal, the eNB may notify the UE of the downlink signal, the interval between the downlink signal / uplink signal, and the respective structure information of the uplink signal. The UE may calculate the length of the interval after the transmission of the uplink signal based on the above respective structure information. As a method for calculating the length of the interval after the transmission of the uplink signal, for example, the length obtained by subtracting the sum of the lengths of the downlink signal, the interval between the downlink signal / uplink signal, and the respective lengths of the uplink signal from the self - contained sub - frame length may be set as the length of the interval after the transmission of the uplink signal. The UE may use the above calculation result as the setting of the interval after the transmission of the uplink signal.

[0209] The setting of the interval after the transmission of the uplink signal, and the respective settings of the downlink signal, the interval between the downlink signal / uplink signal, and the uplink signal may be performed simultaneously or separately.

[0210] In addition, regarding the setting of the interval after the transmission of the uplink signal and the interval between the downlink signal / uplink signal, the eNB and the UE may change the length of one interval, so that the length of the other interval changes correspondingly. For example, the sum of the length of the interval after the transmission of the uplink signal and the length of the interval between the downlink signal / uplink signal may be made constant.

[0211] The UE may change the respective structure information of the downlink signal, the interval between the downlink signal / uplink signal, and the uplink signal according to the length of the interval after the transmission of the uplink signal notified by the eNB and use it. For example, when the eNB notifies the UE of a change in the interval length of the uplink signal, the UE may change the downlink signal length. Or, the length of the interval between the downlink signal / uplink signal may be changed. Or, the uplink signal length may be changed. Or, the downlink signal length, the length of the interval between the downlink signal / uplink signal, and the uplink signal length may be combined for change. At this time, the sum of the downlink signal length, the length of the interval between the downlink signal / uplink signal, the uplink signal length, and the length of the interval after the transmission of the uplink signal may be made constant.

[0212] As specific examples of the setting unit of the interval after the transmission of the uplink signal, the following four (1) to (4) are disclosed.

[0213] (1) Fixed within the eNB.

[0214] (2) Set for each UE.

[0215] (3) Set for each HARQ process.

[0216] (4) The combination of the above (1) to (3).

[0217] Regarding the above (1), it can be notified to the UEs within the eNB. Broadcast information can also be used. As the broadcast information, SIB1 or SIB2 can be used. Alternatively, it can be notified to each UE. In the notification to each UE, RRC dedicated signaling, MAC signaling, or L1 / L2 signaling can be used.

[0218] Regarding the above (2), it can be notified to each UE. It can be notified to the UEs within the eNB. Broadcast information can also be used. In the notification to each UE, RRC dedicated signaling, MAC signaling, or L1 / L2 signaling can be used.

[0219] Regarding the above (3), it can be notified to each UE. In the notification to each UE, it can be sent by aggregating the interval lengths after the transmission of the uplink signals of each HARQ process, or it can be sent separately. In the notification to each UE, the identifier of each HARQ process can be used. Alternatively, in the notification to each UE, RRC dedicated signaling, MAC signaling, or L1 / L2 signaling can be used.

[0220] Regarding the above (3), it can be notified to each HARQ process. In the notification to each HARQ process, MAC signaling or L1 / L2 signaling can be used. Thereby, Ack / Nack can be sent in advance in a subframe with less downlink data, and the eNB can perform the decoding process and scheduling process of Ack / Nack in a relaxed manner. In addition, since there is a margin in the processing time, the eNB can perform other processes such as device control.

[0221] As specific examples of the information required for the eNB to determine the interval length after the transmission of the uplink signal, the following nine (1) to (9) are disclosed.

[0222] (1) The Ack / Nack decoding ability of the eNB. For example, the time required for the eNB to perform the above decoding.

[0223] (2) The scheduling ability of the eNB. For example, the time required for the eNB to perform scheduling.

[0224] (3) The encoding ability of the eNB. For example, the time required for the eNB to encode the downlink user data.

[0225] (4) The decoding ability of the UE. For example, the time required for the UE to decode the downlink user data.

[0226] (5) The Ack / Nack encoding ability of the UE. For example, the time required for the UE to perform the above encoding.

[0227] (6) Downlink signal length.

[0228] (7) Interval length between downlink signal and uplink signal.

[0229] (8) Uplink signal length.

[0230] (9) Combinations of the above (1) to (8).

[0231] In the above (9), for example, the eNB can determine the interval length after uplink transmission by taking into account the margins of the time from the reception of the downlink signal to the transmission of Ack / Nack by the UE and the time from the reception of Ack / Nack to the transmission of downlink user data in the next subframe by the eNB, respectively.

[0232] The determination of the interval length after uplink signal transmission can be performed by the upper network device. The upper network device can send the interval length after uplink signal transmission to the UE via the eNB.

[0233] As specific examples of the above judgment conditions for the upper network device to determine the interval length after uplink signal transmission, the following three (1) to (3) are disclosed.

[0234] (1) Interval length after uplink signal transmission in the eNBs near the eNB.

[0235] (2) Default value of the interval length after uplink signal transmission in the eNBs near the eNB.

[0236] (3) Combinations of the above (1) and (2).

[0237] The upper network device can send a request for the information in the above (1) to the eNBs near the eNB. The eNBs near the eNB can also send the information in the above (1) to the upper network device.

[0238] The upper network device can send a request for the information in the above (2) to the eNB. The eNB can also send the information in the above (2) to the upper network device.

[0239] By setting the interval after uplink signal transmission with the upper network device as the main body, a setting that takes into account the conditions of other eNBs can be performed, so inter-cell interference can be suppressed.

[0240] The eNB and the UE can change the scheduling method of the downlink signal together when the eNB sets the interval length after the transmission of the uplink signal to the UE. The eNB can send an identifier indicating the scheduling method to the UE. As an example of the identifier indicating the scheduling method, it can be a flag indicating whether retransmission in the next subframe is possible. Alternatively, the above flag can be included in the identifier indicating the scheduling method.

[0241] The change in the scheduling method performed by the eNB and the UE can be carried out simultaneously when the setting of the interval length after the uplink transmission becomes effective. Alternatively, regarding the change in the scheduling method of the downlink signal performed by the setting change of the interval length after the uplink transmission, the correspondence can be determined by a standard. For example, when the interval length after the uplink transmission is less than a predetermined value, it can be determined by a standard that retransmission in the next subframe is not allowed.

[0242] In addition, when the eNB sets the interval length after the transmission of the uplink signal to the UE, the eNB and the UE can not change the scheduling of the downlink signal. The UE can receive the downlink user data according to the downlink control signal sent from the eNB, regardless of whether the eNB sets the interval length after the transmission of the uplink signal to the UE. Alternatively, the UE can receive the downlink user data according to the scheduling provided by the eNB in advance.

[0243] The above change in the scheduling method can also be performed on the uplink signal. The change in the scheduling method of the downlink signal and the uplink signal can be carried out simultaneously or separately.

[0244] Figure 8 It is a diagram showing an example of the process related to the setting of the interval length after the transmission of the uplink signal in a self - contained subframe. Figure 8 It shows an example of the following situation: In the initial connection of the UE, the eNB uses broadcast information to set the default value of the interval length after the transmission of the uplink signal, and after the RRC connection is established, the UE - specific interval length after the transmission of the uplink signal is set quasi - statically.

[0245] In step ST800, the eNB broadcasts the default value of the interval length after the uplink transmission to the UE. The broadcast can be carried out using broadcast information. In addition, as the broadcast information, for example, SIB1 can be used.

[0246] In step ST801, the UE reflects the default value of the interval length after the uplink transmission. Thereby, the UE starts the RRC connection process with the eNB.

[0247] Steps ST802, ST803, ST804, ST805 and ST806 represent random access processing and RRC connection processing.

[0248] In step ST802, the UE notifies the eNB of a RA preamble. The notification of the RA preamble uses, for example, the PRACH.

[0249] In step ST803, the eNB sends a RA Response to the UE. The eNB also notifies uplink grant information used in the transmission of the RRC connection request from the UE.

[0250] In step ST804, the UE sends an RRC Connect Request to the eNB. The RRC connection request can be sent using the radio resources specified by the above uplink grant information.

[0251] In step ST805, the eNB sends an RRC Connection Setup to the UE. It can be sent together with contention resolution in the series of RA procedures in steps ST802, ST803 and ST804.

[0252] In step ST806, the UE notifies the eNB of RRC Connection Setup Complete. Thereby, the RRC connection between the eNB and the UE is completed.

[0253] In step ST807, the eNB determines the interval length after uplink transmission for this UE.

[0254] In step ST808, the eNB sends the determined interval length after uplink transmission to the UE. The interval length after uplink transmission can be sent using RRC dedicated signaling. In addition, information on when the interval length after uplink transmission becomes valid can also be notified.

[0255] In step ST809, the UE reflects the interval length after uplink transmission received from the eNB. In step ST810, the eNB reflects the interval length after uplink transmission sent to the UE. Thereby, the UE and the eNB communicate using the new interval length.

[0256] The interval length after uplink transmission can be changed according to the type of uplink signal. As the types of uplink signals, for example, they can be uplink user data, Ack / Nack, CQI, CSI, SRS, and PRACH. By changing the interval length after uplink transmission according to the type of uplink signal, the interval length after uplink transmission can be set without waste based on the differences in the processing times of the respective uplink signals in the eNB.

[0257] The eNB can notify the UE of the interval length after uplink transmission for each type of uplink signal at any time. The above notification can use L1 / L2 signaling. Alternatively, the eNB can notify the UE of a list of the interval lengths for each type of uplink signal. The above notification can use RRC dedicated signaling, MAC signaling, or L1 / L2 signaling. The eNB can notify the UE of an identifier indicating the type of uplink signal together.

[0258] The notification of the above identifier can use L1 / L2 signaling. Alternatively, the eNB can notify the UE of the pattern of the types of uplink signals for each subframe. In the notification of the above pattern, RRC dedicated signaling, MAC signaling, or L1 / L2 signaling can be used.

[0259] The interval length after uplink transmission can be changed through the services of the communication between the eNB and the UE. As the above services, for example, they can be enhanced Mobile Broadband (eMBB), Ultra-Reliable and Low Latency Communication (URLLC), and massive Machine Type Communication (mMTC).

[0260] By using the communication services between the eNB and the UE to change the interval length after uplink transmission, an optimal gap length can be set to meet the necessary conditions of each service. For example, in URLLC, the interval length after uplink transmission is set so that a retransmission from the eNB can be sent in the next subframe after receiving a Nack from the UE. In addition, in eMBB, by shortening or eliminating the interval length after uplink transmission, the waste of communication associated with the interval can be suppressed and the communication speed can be increased.

[0261] In the communication between the eNB and the UE, it is sufficient for the eNB to determine the interval length after each service's uplink transmission. Alternatively, it can be determined in advance by a standard. The eNB can notify the interval length after each service's uplink transmission, or it can also notify each UE. The above broadcast can use broadcast information. For example, the broadcast information can use SIB1 or SIB2. In addition, in the above notification, RRC dedicated signaling can be used. Alternatively, MAC signaling can also be used. Thus, according to the combination with the above identification, the eNB and the UE can obtain the interval setting in the used service.

[0262] The eNB can notify the UE of multiple identifiers representing the above services. Thus, when the eNB and the UE correspond to multiple services at the same time, appropriate interval settings can be provided for each service, and thus, the communication efficiency can be improved.

[0263] The eNB can notify the UE of the identifier representing the service between the eNB and the UE. The above notification can use RRC dedicated signaling, MAC signaling, or L1 / L2 signaling.

[0264] According to Embodiment 1, in a self - contained subframe, a subframe structure with an interval set after the uplink transmission can be used. Thus, for the Ack / Nack from the UE, the eNB can perform re - transmission in the next subframe. Thus, low - latency communication can be performed.

[0265] Variant Example 1 of Embodiment 1.

[0266] In this variant example, a setting method for reducing the interval in a self - contained subframe will be described.

[0267] As a frame structure in NR, for example, it is proposed that by allocating uplink user data before and after uplink control signals such as Ack / Nack, the interval between the downlink signal and the uplink signal can be reduced and the interval after the uplink transmission can be omitted (refer to 3GPP R1 - 166410 (hereinafter referred to as "Reference 2")).

[0268] However, in Reference 2, a method for allocating uplink user data before and after the uplink control signal is not disclosed. Therefore, the UE cannot recognize this subframe structure, and there is a problem that the uplink signal cannot be transmitted.

[0269] In this variant example, a method for solving the above problem is disclosed.

[0270] The eNB notifies the UE of the structure of the uplink signal.

[0271] Specific examples of the information notified as the structure of the uplink signal are disclosed as the following (1) to (4).

[0272] (1) Types of uplink signals.

[0273] (2) Length of the uplink signal.

[0274] (3) Start timing of the uplink signal.

[0275] (4) Combinations of (1) to (3) above.

[0276] Regarding the types of uplink signals in (1) above, identifiers can be used for communication. In addition, as types of uplink signals, for example, uplink user data, uplink control information, uplink reference signals, and intervals can be included. The above uplink control information can include Ack / Nack, CQI, and CSI. The above uplink reference signals can include uplink data demodulation reference signals and uplink sounding reference signals.

[0277] Regarding the length of the uplink signal in (2) above, for example, it can be provided in the minimum time unit in the 5G radio access system. In addition, it can be provided in symbol units or in other units. In addition, it can also be provided as a ratio relative to the subframe length.

[0278] Regarding the start timing of the uplink signal in (3) above, for example, it can be provided as the time from the start of the subframe. In addition, it can be provided as the time traced back from the end of the subframe. Additionally, it can also be provided as the time from the end of the downlink signal.

[0279] In addition, regarding the time unit of the start timing of the uplink signal in (3) above, for example, it can be provided in the minimum time unit in the 5G radio access system, can be provided in symbol units, or can be provided in other units. In addition, it can also be provided as a ratio relative to the subframe length.

[0280] In (1) to (3) above, multiple settings can be made. For example, when there are multiple types of uplink signals transmitted in a certain subframe, for each of the multiple types of uplink signals, the settings in (1) to (3) above can be used.

[0281] Regarding the structure of the uplink signal in this modification example, a signal that does not require a response in the next subframe can be configured near the end of the subframe. For example, the structure of the uplink signal can be set to uplink user data, Ack / Nack, uplink user data, and uplink user data can be configured at the end of the subframe. Or, an uplink reference signal can be configured instead of the uplink user data at the end of the subframe.

[0282] Figure 9 FIG. is a diagram showing an example of the structure of an uplink signal in a self - contained subframe (hereinafter sometimes referred to as "uplink signal structure"). Figure 9 In, the uplink signal is composed of uplink user data, Ack / Nack, uplink user data, and uplink sounding reference signal. In addition, Figure 9 In, the start timing of each of the above - mentioned uplink signals is provided as the timing received at the eNB and is provided as the time from the start of the subframe. For example, the start timing of the first uplink user data is provided as s1, Ack / Nack as s2, the second uplink user data as s3, and the uplink sounding reference signal as s4.

[0283] In this modification, the timing of the uplink signal can be provided as the timing at which the UE transmits. For example, in the Figure 9 example, the start timing of the first uplink user data can be set to t1, Ack / Nack to t2, the second uplink user data to t3, and the uplink sounding reference signal to t4 for provision.

[0284] In this modification, it is possible to notify together when the structure of the uplink signal notified from the eNB to the UE becomes valid. In the notification of when it becomes valid, for example, the moment when it becomes valid can be directly specified, or the time difference required from the notification moment to becoming valid can be specified. As the above - mentioned moment, the subframe number can be used. In addition, as the above - mentioned time difference, the number of subframes can be used. Thus, the switching of the uplink signal structure can be performed simultaneously between the eNB and the UE, and therefore, the transmission / reception loss between the eNB and the UE due to the switching of the uplink signal structure can be prevented.

[0285] In addition, it can be set to select the structure of the uplink signal from several options. For example, the list of options and an identifier indicating which one is selected from the above - mentioned list can be notified from the eNB to the UE. The above - mentioned identifier can be notified together with the list of options or separately.

[0286] As a specific example of the method for notifying the structure of the uplink signal, the following three (1) to (3) are disclosed.

[0287] (1) Semi - static setting.

[0288] (2) Dynamic setting.

[0289] (3) A combination of (1) and (2) above.

[0290] Regarding the quasi-static setting of the above (1), for example, it can be notified by the eNB to the subordinate UEs. As an example of broadcasting, for example, RRC common signaling can be used. As an example of RRC common signaling, for example, SIB1 or SIB2 can be used.

[0291] In addition, as other examples of the quasi-static setting of the above (1), RRC dedicated signaling can be used. As RRC dedicated signaling, for example, RRC connection reconfiguration can be used. Or, message 4 in the random access procedure can also be used.

[0292] Through the quasi-static setting of the above (1), the eNB can notify the UE of the structure of the uplink signal with a smaller amount of signaling.

[0293] Regarding the dynamic setting of the above (2), for example, L1 / L2 signaling can be used. Thus, the uplink signal structure can be changed for each TTI or for each subframe, and therefore, the change of the uplink signal structure can be performed within a shorter period.

[0294] In addition, as other examples of the dynamic setting of the above (2), MAC signaling (MAC Control Element) can be used. Since MAC signaling controls retransmission, the setting can be notified with higher reliability.

[0295] Regarding the setting of the above (3), as one combination, the eNB can quasi-statically and dynamically set different setting contents for the UE respectively. For example, the mainly used uplink signal structure can be specified quasi-statically, and the uplink signal structure used suddenly can be set dynamically. Thus, a flexible setting of the interval length after uplink transmission can be performed with a smaller amount of signaling.

[0296] In this modification example, the eNB can aggregate the uplink signal structures corresponding to multiple subframes and notify the UE. In the above uplink signal structures, the uplink signal structures for each subframe can be different from each other. In the notification of the uplink signal structures corresponding to multiple subframes, an identifier indicating which option is selected from the above can be used. In the notification of the uplink signal structures corresponding to multiple subframes, the number of subframes to be the notification object can also be notified together.

[0297] In the notification of the uplink signal structures corresponding to the above multiple subframes, RRC dedicated signaling, MAC signaling, or L1 / L2 signaling can be used. As an example of RRC dedicated signaling, RRC connection reconfiguration can be used.

[0298] The eNB can use an uplink signal structure equivalent to multiple subframes to transmit downlink signals equivalent to multiple subframes and receive uplink signals.

[0299] In addition, the UE can use an uplink signal structure equivalent to multiple subframes to receive downlink signals equivalent to multiple subframes and transmit uplink signals.

[0300] For the above uplink signal structure equivalent to multiple subframes, an expiration period can be set, or it can be left unset. In the case where no expiration period is set, the eNB and the UE can communicate periodically according to the notified uplink signal structure. In addition, in the case where an expiration period is set, the expiration period can be set to once (one cycle), or the eNB can separately notify the UE of the number of valid times or the valid time. Therefore, by the eNB notifying the UE once of the uplink signal structure equivalent to multiple subframes, communication can be continued, and thus the signaling amount can be reduced.

[0301] In addition, for the uplink signal structure, a default setting can be set. As a situation where the above default setting is required, for example, when the UE is connected to the eNB. When the UE is connected to the eNB, it is necessary to receive broadcast information and paging signals, and in addition, it is necessary to transmit a physical random access channel. At this time, the UE can communicate with the eNB through a subframe structure based on the above default structure.

[0302] As specific examples of the information used by the eNB to determine the uplink signal structure, the following four items (1) to (4) are disclosed.

[0303] (1) The buffer status of uplink user data in the UE. As the buffer status, for example, there is information indicating the buffer margin or information indicating the buffer accumulation amount.

[0304] (2) The channel condition between the eNB and the UE.

[0305] (3) The transceiver switching time in the UE.

[0306] (4) The combination of the above (1) to (3).

[0307] In the above (1), the UE only needs to notify the eNB of the buffer status of the uplink user data. To notify the above buffer status, uplink control information (UCI) can be used. Or, MAC signaling can also be used.

[0308] In (2) above, the eNB can make a determination based on the uplink reference signal from the UE. As the uplink reference signal, the uplink data demodulation reference signal can be used, the uplink sounding signal can be used, or other uplink reference signals can be used. Alternatively, the eNB can also use the CQI sent from the UE.

[0309] In (3) above, the eNB can inquire of the UE about information indicating the transmission and reception switching time of the UE. The UE can notify the eNB of information indicating the transmission and reception switching time of the UE. The above inquiry can use RRC dedicated signaling. In addition, in the above notification, RRC dedicated signaling can be used. As an example of the information indicating the transmission and reception switching time of the above UE, UE capability can be used.

[0310] In this modification example, the information used by the eNB to determine the uplink structure, the notification method of the necessary information from the UE to the eNB, and the notification method from the eNB of the uplink structure to the UE can be interlocked with each other. For example, it is sufficient to make the notification method of the above necessary information from the UE to the eNB and the notification method from the eNB of the uplink structure to the UE the same. For example, when the eNB determines the uplink structure based on the buffer status of the uplink user data in the UE, the buffer status can be notified from the UE to the eNB using MAC signaling, and the uplink structure can be notified from the eNB to the UE using MAC signaling. Thus, the eNB can track changes in the above necessary information and determine the uplink structure and notify the UE using a method with less signaling waste.

[0311] Figure 10 It is a diagram showing an example of a process related to the setting of the uplink signal structure in a self - contained subframe. Figure 10 shows an example of the following situation: In the initial connection of the UE, the eNB sets the default value of the interval length after the transmission of the uplink signal in the broadcast information, and dynamically sets the UE - specific uplink signal structure after the establishment of the RRC connection. Figure 10 The process shown contains the same steps as the process shown in Figure 8 Therefore, the same step numbers are assigned to the same steps, and the common description is omitted.

[0312] Figure 10 sets step ST1000 to replace the step ST800 in Figure 8 In step ST1000, the eNB notifies the UE of the broadcast information SIB1 including the default setting of the uplink signal structure. The UE acquires the default setting of the uplink signal structure included in the broadcast information SIB1 sent from the eNB.

[0313] Figure 10 In it, step ST1001 is set to replace Figure 8 step ST801. In step ST1001, the UE reflects the default setting of the uplink signal structure.

[0314] Figure 10 In it, step ST1002 is set to replace Figure 8 step ST807. In step ST1002, the eNB determines the uplink signal structure.

[0315] Figure 10 In it, step ST1003 is set to replace Figure 8 step ST808. In step ST1003, the eNB notifies the uplink signal structure to the UE by using L1 / L2 signaling.

[0316] Figure 10 In it, step ST1004 is set to replace Figure 8 step ST809. In step ST1004, the UE reflects the uplink signal structure received from the eNB.

[0317] In addition, Figure 10 In it, step ST1005 is set to replace Figure 8 step ST810. In step ST1005, the eNB reflects the uplink signal structure.

[0318] In this modified example, the UE can determine the uplink signal structure. The UE can notify the eNB of the uplink signal structure determined as described above. The following structure can be adopted, that is: for the uplink signal structure notified from the UE, the eNB can notify the UE of a response of approval or rejection. Thus, when the UE communicates with multiple eNBs simultaneously, it is only necessary for the UE to notify the uplink signal structure to the multiple eNBs once, so that the signaling generated between the eNBs can be reduced.

[0319] Alternatively, in this modified example, the following structure can also be adopted, that is: for the uplink signal structure notified from the UE, the eNB does not notify the UE of a rejection response. Thus, the UE can automatically determine the meaning of the response indicating rejection, so that the amount of signaling can be reduced.

[0320] In addition, as another example, the eNB can notify the UE of the uplink signal structure that can be set together with the above rejection response. Thus, the duplication of the notification of the uplink signal structure from the UE and the rejection response from the eNB can be prevented. Therefore, the amount of signaling can be reduced and the structure of the uplink signal can be set quickly.

[0321] To determine the approval or rejection of the uplink signal structure, the eNB may use the subframe structure of other UEs connected to the UE.

[0322] As specific examples of the information required for the UE to determine the uplink signal structure, the following four items (1) to (4) are disclosed.

[0323] (1) The buffer status of the uplink user data in the UE. As the buffer status, for example, there is information indicating the buffer margin or information indicating the buffer accumulation amount.

[0324] (2) The channel condition between the eNB and the UE.

[0325] (3) The transceiver switching time in the UE.

[0326] (4) The combination of the above (1) to (3).

[0327] Regarding the above (2), the eNB may notify the UE of the status of the uplink channel. As the status of the uplink channel, for example, the MCS can be used. As the MCS, for example, it can be included in the uplink grant information. When notifying the uplink channel status, RRC dedicated signaling, MAC control information, or uplink L1 / L2 signaling can be used.

[0328] In addition, regarding the above (2), the UE may also use the status of the downlink channel. As the downlink channel status, the CQI can be used.

[0329] When the UE notifies the eNB of the uplink signal structure, RRC dedicated signaling can be used. Or, MAC control information can also be used. Or, L1 / L2 signaling can also be used.

[0330] When including uplink user data as the uplink signal structure, the eNB may notify the UE of scheduling information through this subframe. As the scheduling information, L1 / L2 signaling can be used.

[0331] According to this modification example, the interval between the downlink signal and the uplink signal in the self - contained subframe can be reduced, and the interval after the transmission of the uplink signal can be omitted. Therefore, radio resources can be used efficiently. In addition, in the self - contained subframe, the structure of the uplink signal can be set flexibly.

[0332] Modification Example 2 of Embodiment 1.

[0333] In this modification example, a scheduling method for reducing the interval in the self - contained subframe is described.

[0334] In the existing scheduling, in order to retransmit to the UE by the eNB in the next subframe after receiving the Nack from the UE, an interval is allowed to be generated in the eNB after the reception of the Ack / Nack (refer to Non-Patent Document 11).

[0335] However, since an interval is generated after the reception of the Ack / Nack, the resource utilization efficiency will decrease. By using the method of Modification Example 1 of Embodiment 1, an interval after the reception of the Ack / Nack can be allocated to the uplink signal. However, in the case where there is no uplink signal that can be transmitted by the UE, there is a problem that the interval after the reception of the Ack / Nack remains.

[0336] In this modification example, a method for solving the above problems is disclosed. In this modification example, the eNB determines the retransmission scheduling n subframes before. Here, n is set to an integer of 1 or more. Symmetric scheduling may be performed. The eNB may use the scheduling for the initial transmission, or may use the retransmission scheduling. The eNB may also use both the scheduling for the initial transmission and the retransmission scheduling. The Ack / Nack sent from the UE can be used to determine which scheduling the eNB uses.

[0337] For example, when n = 1, in the subframe in which the initial transmission data is sent, the retransmission scheduling is performed in advance.

[0338] In addition, for example, when n = 2, in the subframe before the initial transmission data is sent, the retransmission scheduling is performed. At this time, the scheduling for the initial transmission data may be performed together.

[0339] In addition, in this modification example, the scheduling for the initial transmission n subframes before may also be performed together. For example, when n = 2, the scheduling for the initial transmission data 2 subframes before may be performed.

[0340] Adaptive scheduling may be performed at the time of retransmission. That is, scheduling different from the initial transmission may be performed. Non-adaptive scheduling may also be performed.

[0341] In addition, in this modification example, the structure of the uplink signal may be set using Embodiment 1 or Modification Example 1 of Embodiment 1. The structure of the above uplink signal may also include an interval after the reception of the Ack / Nack. The same shall also apply to the subsequent modification examples and embodiments.

[0342] In the case of n = 1, the operations of the eNB and the UE in this modification example are shown.

[0343] The eNB determines the initial transmission scheduling.

[0344] In the next subframe, the eNB sends the information of the above-mentioned initial transmission scheduling to the UE. The information of the initial transmission scheduling can be sent using a downlink control signal. In addition, the eNB sends the initial transmission data to the UE. In addition, scheduling of the retransmission data for the above-mentioned initial transmission data is performed. It is sufficient to perform scheduling of the next initial transmission data together.

[0345] There may be a repetition of frequency resources between the retransmission data and the next initial transmission data. At this time, the eNB can use the Ack / Nack from the UE to send either the next initial transmission data or the retransmission data in the next subframe. In addition, the frequency resources of the retransmission data and the next initial transmission data may be different. At this time, the eNB can send the retransmission data and the next initial transmission data simultaneously in the next subframe, or can send only one of them.

[0346] The UE receives the above-mentioned downlink control signal. In addition, the UE obtains the information of the above-mentioned initial transmission scheduling from the above-mentioned downlink signal. In addition, the UE receives the above-mentioned initial transmission data according to the information of the above-mentioned scheduling. The UE sends the Ack / Nack for the above-mentioned initial transmission data to the eNB.

[0347] In addition, when the UE sends an Ack for the above-mentioned initial transmission data, the UE releases the received data for HARQ. In addition, when the UE does not send an Ack for the above-mentioned initial transmission data, the UE retains the received data for HARQ. The retained received data for HARQ is used for combining and decoding with the retransmission data received from the eNB. The above-mentioned received data for HARQ is retained until an Ack is sent for the retransmission or until the number of retransmissions is full.

[0348] The eNB receives the Ack / Nack from the UE. The eNB determines the scheduling to be used in the next subframe based on the Ack / Nack from the UE. For example, when an Ack is received, the eNB uses the scheduling for the next initial transmission in the next subframe. In addition, for example, when a Nack is received, the eNB uses the scheduling for retransmission in the next subframe.

[0349] In the next subframe, the eNB sends the information of the scheduling determined in the previous subframe. In addition, the eNB sends the downlink user data indicated by the information of the scheduling to the UE. In addition, the eNB also performs scheduling of the downlink user data to be sent in the next subframe. The method of scheduling is the same as that in the previous subframe.

[0350] Next, the eNB and the UE repeat the above actions.

[0351] Figure 11 and Figure 12 is a diagram showing an example of a method for performing scheduling one frame before in Modification Example 2 of Embodiment 1.Figure 11 and Figure 12 In, an example where n = 1 is shown for the scheduling in Modification Example 2 of Embodiment 1. Figure 11 Connected to at the position of the boundary line BL1. In Figure 12 and Figure 11 and Figure 12 the horizontal axis represents time t and the vertical axis represents frequency f. In Figure 11 and Figure 12 scheduling corresponding to the Ack and Nack of this subframe is performed in advance, and the scheduling used is switched according to the Ack / Nack from the UE and used in the next subframe.

[0352] Figure 13 and Figure 14 are diagrams showing an example of a method for retransmission scheduling two frames before in Modification Example 2 of Embodiment 1. Figure 13 and Figure 14 In, an example where n = 2 is shown for the scheduling in Modification Example 2 of Embodiment 1. Figure 13 Connected to at the position of the boundary line BL2. In Figure 14 and Figure 13 and Figure 14 the horizontal axis represents time t and the vertical axis represents frequency f.

[0353] In Figure 13 and Figure 14 initial transmission scheduling to be used in the next subframe and retransmission scheduling to be used in the subframe two later are performed in advance, and which scheduling to use is switched according to the Ack / Nack of this subframe and the Ack / Nack of the next subframe. In addition, regarding the retransmission scheduling, since data to be used in the subframe two later is scheduled, it becomes scheduling for the following: retransmission data for the next initial transmission and second retransmission data for the current initial transmission data.

[0354] Figure 15 and Figure 16 are diagrams showing an example of a method for scheduling initial transmission and retransmission two frames before in Modification Example 2 of Embodiment 1. Figure 15 and Figure 16 In, an example is shown where scheduling is also performed for the initial transmission n subframes before in Modification Example 2 of Embodiment 1. In Figure 15 and Figure 16 an example where n = 2 is shown. Figure 15 Connected to at the position of the boundary line BL3. In Figure 16 and Figure 15 and Figure 16 the horizontal axis represents time t and the vertical axis represents frequency f.

[0355] In Figure 15 and Figure 16 For the first transmission and retransmission, scheduling for use in the two subsequent subframes is also performed, and which scheduling to use is switched according to the Ack / Nack of this subframe and the next subframe. The number of schedulings performed in one subframe is a power of 2. Therefore, in Figure 15 and Figure 16 the number of schedulings performed in one subframe becomes 2 squared, that is, 4.

[0356] In this modification example, the following five (1) to (5) are disclosed as specific examples of the information required to determine the value of n.

[0357] (1) Uplink signal structure. For example, the timing of Ack / Nack. Or, for example, the interval length after the transmission of the uplink signal.

[0358] (2) The time required for the eNB to decode the Ack / Nack.

[0359] (3) The time required for the eNB to encode the downlink signal.

[0360] (4) Subframe length.

[0361] (5) The combination of (1) to (4) above.

[0362] The uplink signal structure in the above (1) can be, for example, in the same form as in Modification Example 1 of Embodiment 1. Or, for example, it can also be information including any one or more of the start timing, length, and end timing of the Ack / Nack symbol.

[0363] In this modification example, the time required for encoding the downlink signal in the above (3) for determining the value of n can be the time required for encoding the downlink control information. Or, it can be the time required for encoding the downlink user data. Or, it can also be both the time required for encoding the above downlink control information and the time required for encoding the downlink user data.

[0364] In this modification example, the value of n can be provided fixedly by the standard. Or, it can be broadcast by the eNB to the UE. Broadcast information can be used in the broadcast. As the broadcast information, SIB1 or SIB2 can be used. Or, it can be notified by the eNB to the UE through RRC dedicated signaling. In addition, the value of n can be set only once when the UE is connected to the eNB, or it can be changed after the connection.

[0365] According to this modification example, in the next subframe after receiving Ack / Nack, the eNB can retransmit the downlink user data to the UE. Therefore, communication latency can be suppressed. In addition, the interval after the transmission of the uplink signal can be reduced, and thus, efficient communication can be achieved.

[0366] Modification Example 3 of Embodiment 1.

[0367] In this modification example, a scheduling method will be described in which the interval after the transmission of the uplink signal is not set in the self - contained subframe, and retransmission is enabled in the next subframe after receiving Ack / Nack.

[0368] In the method of Modification Example 2 of Embodiment 1, although the interval after the transmission of the uplink signal can be reduced, the time required for decoding the Ack and Nack from the UE cannot be completely eliminated. Therefore, there is a problem that the interval after the transmission of the uplink signal cannot be completely eliminated.

[0369] In this modification example, a method for solving the above - mentioned problem is disclosed.

[0370] After the initial transmission, the eNB performs retransmission in m subframes. Here, m is set as an integer of 1 or more. Symmetric scheduling is performed. The eNB can apply the Ack / Nack from the UE to the data transmitted in the (m + 1) - th subsequent subframe.

[0371] In Modification Example 3 of Embodiment 1, in that the data to be transmitted from the eNB to the UE is transmitted in multiple subframes, it is the same as TTI bundling as the prior art (for example, refer to Reference 1), but it is different from TTI bundling in that different scheduling can be performed for the retransmitted data compared to the initial transmission.

[0372] For example, when m = 1, the eNB performs scheduling after receiving the above - mentioned Ack / Nack. When receiving an Ack, the eNB starts scheduling the next initial - transmission data. In addition, the eNB transmits the retransmitted data to the UE in the next subframe. In addition, in the next subframe, the eNB transmits the above - mentioned next initial - transmission data to the UE. When receiving a Nack, the eNB starts scheduling the second retransmitted data. The eNB transmits the retransmitted data to the UE in the next subframe. In addition, in the next subframe, the eNB transmits the above - mentioned second retransmitted data to the UE.

[0373] In addition, similar to Modification Example 2 of Embodiment 1, the eNB pre - determines the scheduling for retransmission n subframes before. Here, n is set as an integer of 1 or more. The Ack / Nack transmitted from the UE can be used to determine which scheduling the eNB uses.

[0374] For example, when n = 1, scheduling for retransmission is performed in advance in the subframe in which the initial transmission data is sent.

[0375] In addition, for example, when n = 2, scheduling for retransmission is performed in the subframe before the initial transmission data is sent. At this time, scheduling for the initial transmission data can be performed together.

[0376] In addition, in this modified example, scheduling for the initial transmission n subframes before can also be performed together. For example, when n = 2, scheduling for the initial transmission data two subframes before can be performed.

[0377] Adaptive scheduling can be performed during retransmission. That is, scheduling different from the initial transmission can be performed. Through adaptive scheduling, the eNB can perform scheduling that flexibly responds to changes in the radio environment. In addition, non - adaptive scheduling can also be performed. Through non - adaptive scheduling, the UE does not need to perform decoding processing of the downlink control information during retransmission reception. Therefore, the processing load in the UE is reduced.

[0378] In the case of m = 1 and n = 1, the operations of the eNB and the UE in this modified example are shown.

[0379] The eNB determines the initial transmission scheduling.

[0380] In the next subframe, the eNB sends the information of the above - mentioned initial transmission scheduling to the UE. The information of the initial transmission scheduling can be sent using the downlink control signal. In addition, the eNB sends the initial transmission data to the UE. In addition, scheduling for the retransmission data of the above - mentioned initial transmission data is performed.

[0381] The UE receives the above - mentioned downlink control signal. In addition, the UE obtains the information of the above - mentioned initial transmission scheduling from the above - mentioned downlink signal. In addition, the UE receives the above - mentioned initial transmission data according to the information of the above - mentioned scheduling. The UE sends the Ack / Nack for the above - mentioned initial transmission data to the eNB.

[0382] In addition, when the UE sends an Ack for the above - mentioned initial transmission data, the received data for HARQ is released. In addition, when the UE does not send an Ack for the above - mentioned initial transmission data, the received data for HARQ is kept. The kept received data for HARQ is used for combining and decoding with the retransmission data received from the eNB. The above - mentioned received data for HARQ is kept until an Ack is sent for the retransmission or the number of retransmissions is full.

[0383] The eNB receives Ack / Nack from the UE. Based on the Ack / Nack from the UE, the eNB determines the scheduling to be used in the next subframe. For example, upon receiving an Ack, the eNB uses the scheduling for the next initial transmission in the next subframe. Additionally, for example, upon receiving a Nack, the eNB uses the scheduling for the second retransmission in the next subframe.

[0384] In the next subframe, the eNB sends the scheduling information determined in the previous subframe to the UE. Additionally, the eNB sends the downlink user data indicated by the scheduling information to the UE. Furthermore, the eNB also performs the scheduling of the downlink user data to be sent in the next subframe. The method of scheduling is the same as that in the previous subframe.

[0385] Next, the eNB and the UE repeat the above actions.

[0386] In this modification example, for the retransmitted data for which an Ack is received for the initial transmission, the eNB may not receive Ack / Nack. Or, the above Ack / Nack may not be decoded.

[0387] In this modification example, the UE may not send the Ack / Nack regarding the retransmitted data before the (m - 1)th time to the eNB. The eNB may also not receive the Ack / Nack regarding the retransmitted data before the (m - 1)th time. Thereby, the encoding process of Ack / Nack in the UE can be reduced. Additionally, the decoding process of Ack / Nack in the eNB can be reduced.

[0388] In this modification example, the UE may not receive the retransmitted data after an Ack is sent for the initial transmission. Or, the above retransmitted data may not be decoded. Or, the Ack / Nack regarding the above retransmitted data may or may not be sent to the eNB.

[0389] Furthermore, in this modification example, for the data for which an Ack is received from the UE before the above m - time retransmission, the eNB may not perform retransmission. For example, when m = 2 and an Ack is received from the UE for the initial transmission, the eNB may send the next initial transmission data without sending the data for the second retransmission to the UE. Thereby, the situation where the eNB repeatedly sends the data correctly received by the UE can be suppressed, and an attempt is made to achieve the efficiency of communication between the eNB and the UE.

[0390] Figure 17 and Figure 18 are diagrams showing an example of a method of scheduling one frame before in the case of performing one retransmission in Modification Example 3 of Embodiment 1. Figure 17 and Figure 18In [description], an example of the case where m = 1 and n = 1 is shown for the scheduling in Variation 3 of Embodiment 1. Figure 17 is connected to Figure 18 at the position of the boundary line BL4. In Figure 17 and Figure 18 the horizontal axis represents time t and the vertical axis represents frequency f.

[0391] In Figure 17 and Figure 18 the eNB transmits the initial transmission data to the UE in the next subframe after the initial transmission scheduling. In addition, since there is 1 retransmission, in the next subframe after the initial transmission scheduling, the eNB performs retransmission scheduling and transmits the retransmitted data to the UE in the next subframe.

[0392] In Figure 17 and Figure 18 when the eNB receives an Ack from the UE for the initial transmission, in the next subframe, i.e., the subframe for transmitting the retransmitted data, the eNB schedules the next initial transmission data and transmits the next initial transmission data to the UE in the next subframe. In addition, when the eNB receives a Nack from the UE for the initial transmission, in the next subframe, the eNB schedules the second retransmitted data and transmits the second retransmitted data in the next subframe.

[0393] Figure 19 and Figure 20 are diagrams showing an example of a method of performing retransmission scheduling two frames before in the case of 1 retransmission in Variation 3 of Embodiment 1. Figure 19 and Figure 20 In [description], an example of the case where m = 1 and n = 2 is shown for the scheduling in Variation 3 of Embodiment 1. Figure 19 is connected to Figure 20 at the position of the boundary line BL5. In Figure 19 and Figure 20 the horizontal axis represents time t and the vertical axis represents frequency f.

[0394] In Figure 19 and Figure 20 the eNB simultaneously performs scheduling for the initial transmission and retransmission of DL data #1, and in the next subframe, transmits the initial transmission of DL data #1. In addition, the eNB schedules the second retransmission of DL data #1. The eNB also performs the retransmission of DL data #1 in the next subframe. In addition, since the eNB receives an Ack from the UE for the initial transmission of DL data #1, the eNB schedules the initial transmission and retransmission of DL data #2.

[0395] In Figure 19 and Figure 20Among them, the eNB performs the initial transmission of DL data #2 in the next subframe, and in addition, schedules the second retransmission of DL data #2. The eNB also performs the retransmission of DL data #2 in the next subframe. In addition, a Nack is received from the UE for the initial transmission of DL data #2, so the eNB schedules the third retransmission of DL data #2.

[0396] The eNB transmits the second retransmission of DL data #2 in the next subframe. In addition, an Ack is received from the UE for the retransmission of DL data #2, so the eNB schedules the initial transmission and retransmission of DL data #3. Regarding DL data #3, it is the same as DL data #1.

[0397] Figure 21 and Figure 22 FIG. is an example showing a method of scheduling the initial transmission and retransmission two frames before in the case of performing one retransmission in Modification 3 of Embodiment 1. Figure 21 and Figure 22 Among them, regarding the scheduling in Modification 3 of Embodiment 1, an example is shown in which the initial transmission n subframes before is also scheduled. In Figure 21 and Figure 22 an example in the case of m = 1 and n = 2 is shown. Figure 21 is connected to Figure 22 at the position of the boundary line BL6. In Figure 21 and Figure 22 the horizontal axis represents time t and the vertical axis represents frequency f.

[0398] In Figure 21 and Figure 22 the eNB schedules for the initial transmission of DL data #2 and the second retransmission of DL data #1 in the subframe in which DL data #1 is transmitted. In the next subframe, the eNB retransmits DL data #1 to the UE. In addition, since an Ack is received for the initial transmission of DL data #1, the eNB schedules for the retransmission of DL data #2.

[0399] In addition, in the next subframe, an Ack is received for the initial transmission of DL data #1, so the eNB performs the transmission of the initial transmission of DL data #2 based on the scheduling of DL data #2 scheduled two subframes before. The eNB schedules for the initial transmission of DL data #3 and the second retransmission of DL data #2 together.

[0400] Also, in the next subframe, the eNB transmits a retransmission of DL Data #2. In addition, since a Nack for the initial transmission of DL Data #2 is received, the eNB performs re-scheduling for the initial transmission of DL Data #3 and scheduling for the third retransmission of DL Data #2. Also, in the next subframe, the eNB transmits the second retransmission of DL Data #2. In addition, an Ack is received for DL Data #2, so the eNB performs scheduling for the retransmission of DL Data #3. Also, in the next subframe, the eNB transmits the initial transmission of DL Data #3. For DL Data #3, the same actions as for DL Data #1 are performed.

[0401] In this modification example, the following three (1) to (3) are disclosed as specific examples of the information required to determine the value of m.

[0402] (1) The downlink user data coding time of the eNB.

[0403] (2) The Ack / Nack ratio sent from the UE.

[0404] (3) The combination of (1) and (2) above.

[0405] In this modification example, the value of m can be provided fixedly by a standard. Or, it can be broadcast by the eNB to the UE. Broadcast information can be used for the broadcast. As the broadcast information, SIB1 or SIB2 can be used. Or, it can be notified from the eNB to the UE by RRC dedicated signaling. In addition, the value of m can be set only once when the UE is connected to the eNB, or can be changed after the connection.

[0406] In this modification example, regarding the information required to determine the value of n, since it is the same as that in Modification Example 2 of Embodiment 1, the description is omitted.

[0407] Regarding the method of providing the value of n in this modification example, since it is the same as the method of providing the value of m, the description is omitted.

[0408] According to this modification example, in the next subframe after receiving an Ack / Nack, the eNB can retransmit the downlink user data to the UE, so communication latency can be suppressed. In addition, the interval after the transmission of the uplink signal can be omitted, so communication efficiency can be achieved.

[0409] Embodiment 1 Modification Example 4.

[0410] In this modification example, a scheduling method is described that is not for the downlink control information of the subframe when retransmission is not used in a self-contained subframe, but for enabling retransmission in the next subframe after receiving an Ack / Nack.

[0411] In the methods of Modification 2 of Embodiment 1 and Modification 3 of Embodiment 1, the eNB also sends downlink control information to the UE during retransmission. However, in this modification, scheduling is performed, and the eNB does not send downlink control information to the UE during retransmission.

[0412] During retransmission, the eNB allocates the same frequency resources and the same modulation scheme as in the initial transmission. During retransmission, the redundancy version (RV) can be changed from the initial transmission. As a result, the error correction capability during retransmission is improved.

[0413] Preferably, the correspondence relationship between the number of retransmissions and the RV is shared between the eNB and the UE. The correspondence relationship between the number of retransmissions and the RV can be specified in advance by a standard. The correspondence relationship between the number of retransmissions and the RV can also be broadcast by the eNB to the UE. Broadcast information can be used for the broadcast. As the broadcast information, SIB1 and SIB2 can be used.

[0414] In addition, the correspondence relationship between the number of retransmissions and the RV can be notified by the eNB to the UE through RRC dedicated signaling, or can be notified through MAC signaling. By using MAC signaling, reliability can be maintained using retransmission control, and the correspondence relationship between the number of retransmissions and the RV can be notified more quickly than broadcast information and RRC dedicated signaling. In addition, during retransmission, the RV can also be set to be the same as in the initial transmission.

[0415] The eNB can allocate the symbols allocated to the downlink control information to the downlink user data during retransmission. As a result, the number of physical channel bits during retransmission increases, and the error correction capability is improved. In addition, during retransmission, the eNB can notify the UE of an identifier indicating whether the area of the downlink control information is allocated to the downlink user data, or whether the allocation is performed can be specified by a standard.

[0416] Regarding the above identifier, it can be broadcast by the eNB to the UE. Broadcast information can be used for the broadcast. As the broadcast information, SIB1 and SIB2 can be used. In addition, the above identifier can be notified by the eNB to the UE through RRC dedicated signaling, or can be notified through MAC signaling, or can be notified as the downlink control information of the initial transmission.

[0417] The UE can acquire the above identifier. The UE can also use the above identifier to determine the reception area of the downlink user data during retransmission.

[0418] This modification can be applied to the existing method of scheduling the next subframe using Ack / Nack from the UE. It can also be applied to the scheduling method shown in Modification 2 of Embodiment 1. In addition, this modification can also be applied to the scheduling method shown in Modification 3 of Embodiment 1.

[0419] Shows the operations of the eNB and the UE in this modification example. The eNB performs scheduling for the initial data transmission. The eNB transmits the scheduling information for the initial data transmission. In the transmission of the above scheduling information, a downlink control signal can be used. The eNB transmits the initial data. The UE receives the above initial data. The UE sends the Ack / Nack for the above initial data to the eNB.

[0420] The eNB determines whether retransmission of the initial data is required. In the above determination, the Ack / Nack from the UE can be used. Alternatively, the eNB may also be required to perform retransmission for a specified number of subframes or more after the initial transmission.

[0421] Based on the above determination, the eNB sends the retransmission data to the UE. In the transmission of the above retransmission data, the eNB can use the transmission area of the downlink control information as the reception area of the downlink user data.

[0422] The UE determines whether the received downlink signal is an initial transmission or a retransmission. In the above determination, the Ack / Nack sent to the eNB can be used. Alternatively, a protocol such as that the eNB must perform retransmission for a specified number of subframes or more after the initial transmission can also be used.

[0423] The UE receives the retransmission data from the eNB. In the reception of the retransmission data, whether the eNB uses the transmission area of the downlink control information as the area of the downlink user data can be used. The UE sends the Ack / Nack for the above retransmission data to the eNB.

[0424] The UE can send a scheduling request to the eNB. The above scheduling request from the UE can be sent during the HARQ retransmission of the downlink user data from the eNB. The eNB can, taking the scheduling request from the UE as an opportunity, send scheduling information to the UE. The above scheduling information from the eNB can be for the retransmission data. Thus, the downlink control information during the retransmission of the downlink user data from the eNB can be sent. Therefore, it is possible to recover from a malfunction caused by the eNB misjudging the Ack / Nack from the UE.

[0425] Figure 23 and Figure 24 are diagrams showing an example of a method for performing scheduling one frame before in Modification Example 4 of Embodiment 1. Figure 23 and Figure 24 show an example of the case where n = 1 for the situation of applying this modification example to the scheduling method shown in Modification Example 2 of Embodiment 1. Figure 23 is connected to Figure 24 at the position of the boundary line BL7. At Figure 23 andFigure 24 In this figure, the horizontal axis represents time t and the vertical axis represents frequency f.

[0426] In Figure 23 and Figure 24 for the first transmission of DL data #2, a Nack was returned from the UE. Therefore, in the next subframe, DL data #2 was retransmitted to the UE without a downlink control signal. In addition, the scheduling for the first transmission of DL data #3 was redone. Also, in Figure 23 and Figure 24 the area for the downlink control signal during the transmission of the retransmitted data was allocated as the area for the downlink user data.

[0427] Figure 25 and Figure 26 are diagrams showing an example of a method of performing scheduling one frame before in the case of performing one retransmission in Modification 4 of Embodiment 1. Figure 25 and Figure 26 show an example in the case where m = 1 and n = 1 when this modification is applied to the scheduling method shown in Modification 3 of Embodiment 1. Figure 25 Connects with Figure 26 at the position of the boundary line BL8. In Figure 25 and Figure 26 the horizontal axis represents time t and the vertical axis represents frequency f.

[0428] In Figure 25 and Figure 26 in each retransmission, the transmission area for the downlink user data was allocated in place of the downlink control signal. Also, for the first transmission of DL data #2, a Nack was returned from the UE to the eNB. Therefore, the second retransmission of DL data #2 was performed, and for the above-mentioned second retransmission, the transmission area for the downlink user data was allocated in the same way as the retransmission in place of the downlink control signal.

[0429] According to this modification, in addition to the effects of Modification 2 or Modification 3 of Embodiment 1, the following effects can also be obtained. Specifically, since the notification of the downlink control information during retransmission can be omitted, the signaling amount from the eNB to the UE can be reduced. Also, by allocating the area for the downlink control information during retransmission to the downlink user signal, the error correction ability of the downlink user data during retransmission can be improved. Thereby, the reliability can be improved.

[0430] Embodiment 1 Modification 5.

[0431] In this modification example, other specific examples of a scheduling method for downlink control information of a subframe when retransmission is not used in a self - contained subframe and for enabling retransmission in the next subframe after receiving an Ack / Nack are disclosed.

[0432] In Modification Example 4 of the above - described Embodiment 1, for example, in a subframe that transmits a synchronization signal and a physical broadcast information channel, there is a problem that sometimes the same radio resources as those for the initial data transmission cannot be used due to the subframe.

[0433] In this modification example, a method for solving the above - described problems is disclosed.

[0434] In the scheduling of the initial transmission, scheduling equivalent to k retransmissions is performed. k can be any integer from 1 to the maximum number of retransmissions. k may not be the value of the maximum number of retransmissions. The retransmission is transmitted in a scheduling different from the initial transmission. The retransmission and the initial transmission can be the same scheduling. In addition, in the retransmission, the coding rate can be different from that of the initial transmission.

[0435] The information of the above - described scheduling equivalent to k retransmissions can be notified from the eNB to the UE by L1 / L2 signaling. The information of the above - described scheduling equivalent to k retransmissions can also be notified together with the scheduling of the initial transmission.

[0436] In addition, in the next subframe after the transmission equivalent to k retransmissions ends, the eNB can notify the UE of downlink control information. Thus, even if an Ack is not received in the retransmission equivalent to k times, retransmission can continue.

[0437] In this modification example, the value of k can be set to be common within the cell. Alternatively, the value of k can be set for each UE. Alternatively, the value of k can be set for each process ID.

[0438] The above - described value of k can be determined statically by a standard. Alternatively, it can be broadcast from the eNB to the UE. As the above - described broadcast, for example, broadcast information can be used. As the broadcast information, for example, SIB1 or SIB2 can be used. In addition, the eNB can use RRC dedicated signaling to notify the UE, the eNB can use MAC signaling to notify the UE, or the eNB can use L1 / L2 signaling to notify the UE.

[0439] As specific examples of the information required for the eNB to determine the above - described value of k, the following four (1) to (4) are disclosed.

[0440] (1) The maximum number of retransmissions.

[0441] (2) The ratio of Ack to Nack received from the UE. For example, the block error rate (= Nack / (Ack + Nack)).

[0442] (3) Statistical information on the number of retransmissions generated.

[0443] (4) Combinations of the above (1) to (3).

[0444] As the statistical information in the above (3), for example, the maximum value of the number of retransmissions generated can be used. Alternatively, the upper limit of the number of retransmissions exceeding a specified number can also be used. In addition, for the statistical information in the above (3), the information at the start-up from the eNB can be the object, or a past predetermined period can be the object.

[0445] This modified example can be applied to existing methods that use Ack / Nack from the UE to schedule the next subframe. It can also be applied to the scheduling method shown in Modified Example 2 of Embodiment 1. In addition, this modified example can also be applied to the scheduling method shown in Modified Example 3 of Embodiment 1.

[0446] Shows the operations of the eNB and the UE in this modified example. The eNB performs scheduling for the initial data transmission. The eNB also performs scheduling for the retransmissions equivalent to the above k times. The scheduling information can be different between the initial transmission and the retransmissions. As the above scheduling information, for example, it can include frequency resources, coding rate, or modulation method.

[0447] The eNB sends the information on the above initial data transmission scheduling and the information on the scheduling equivalent to k times of retransmissions to the UE. In the transmission of the information on the above initial data transmission scheduling and the information on the scheduling equivalent to k times of retransmissions, the eNB can use the area of the downlink control information. The eNB sends the initial data together with the information on the above initial data transmission scheduling and the information on the scheduling equivalent to k times of retransmissions to the UE.

[0448] The eNB determines whether retransmission of the above initial data is required. In the above determination, Ack / Nack from the UE can be used. Alternatively, the eNB may also have to perform retransmissions for a specified number of subframes or more after the initial transmission.

[0449] The eNB sends the retransmitted data to the UE based on the above determination. In the above retransmission, the eNB can use the transmission area of the downlink control information as the reception area of the downlink user data. In addition, the eNB can perform the next initial transmission and the scheduling equivalent to k times of retransmissions before receiving Ack from the UE. The eNB can also re-perform the next initial transmission and the scheduling equivalent to k times of retransmissions after the scheduling is completed.

[0450] The UE receives the initial transmission and the scheduling information equivalent to k times of retransmissions.

[0451] The UE determines whether the received downlink signal is a first transmission or a retransmission. In the above determination, the Ack / Nack sent to the eNB can be used. Alternatively, a protocol in which the eNB must perform a retransmission for a specified number of subframes or more after the first transmission can also be used.

[0452] The UE receives retransmitted data from the eNB. In receiving the retransmitted data, whether the eNB uses the transmission area of the downlink control information as the area of the downlink user data can be used. The UE sends the Ack / Nack for the above retransmitted data to the eNB. The UE can discard the scheduling information corresponding to the k-th retransmission or can also hold it.

[0453] Similar to Modification Example 4 of Embodiment 1, the UE can send a scheduling request to the eNB. The above scheduling request from the UE can be sent during the HARQ retransmission of the downlink user data from the eNB. The eNB can send scheduling information to the UE on the occasion of the scheduling request from the UE. The above scheduling information from the eNB can be sent for the retransmitted data. Thus, the downlink control information at the time of retransmitting the downlink user data from the eNB can be sent. Therefore, it is possible to recover from a malfunction caused by the eNB misjudging the Ack / Nack from the UE.

[0454] Figure 27 and Figure 28 FIG. is an example showing a method of performing scheduling one frame before in Modification Example 5 of Embodiment 1. Figure 27 and Figure 28 In, for the case where this modification example is applied to the scheduling method shown in Modification Example 2 of Embodiment 1, an example in the case of n = 1 is shown. Figure 27 Connected to Figure 28 at the position of the boundary line BL9. In Figure 27 and Figure 28 the horizontal axis represents time t and the vertical axis represents frequency f.

[0455] In Figure 27 and Figure 28 the eNB performs the first transmission of DL data #2 and the scheduling corresponding to the k-th retransmission during the first transmission of DL data #1. Then, in the next subframe, the first transmission of DL data #2 and the scheduling information corresponding to the k-th retransmission, and the first transmission data are sent.

[0456] Similarly, during the first transmission of DL data #2, the first transmission of DL data #3 and the scheduling corresponding to the k-th retransmission are performed. Then, in the next subframe, the first transmission of DL data #3 and the scheduling information corresponding to the k-th retransmission, and the first transmission data are sent.

[0457] In Figure 27 and Figure 28 for the first transmission of DL data #2, a Nack was returned from the UE. Therefore, the eNB retransmits DL data #2 and re-performs the first transmission of DL data #3 and the scheduling equivalent to k retransmissions. For the retransmission of DL data #2, an Ack was returned from the UE. Therefore, the eNB transmits the first transmission of DL data #3 and the scheduling information equivalent to k retransmissions, as well as the first transmission data, in its next subframe.

[0458] Figure 29 and Figure 30 are diagrams showing an example of a method of performing scheduling one frame before in the case of performing one retransmission in Modification 5 of Embodiment 1. Figure 29 and Figure 30 show an example of the case where m = 1 and n = 1 when this modification is applied to the scheduling method shown in Modification 3 of Embodiment 1. Figure 29 Connects with Figure 30 at the position of the boundary line BL10. In Figure 29 and Figure 30 the horizontal axis represents time t and the vertical axis represents frequency f.

[0459] After the transmission of DL data, in the next subframe after receiving the first Ack, the eNB performs the next first transmission data and the scheduling equivalent to k retransmissions. Since the first transmission of DL data #1 became an Ack, during the retransmission of DL data #1, the first transmission of DL data #2 and the scheduling equivalent to k retransmissions are performed. However, since the first transmission of DL data #2 became a Nack and became an Ack during the first retransmission of DL data #2, during the second retransmission of DL data #2, the first transmission of DL data #3 and the scheduling equivalent to k retransmissions are performed.

[0460] According to this modification, even when the frequency resources available for the first transmission and retransmission are different, the same effect as in Modification 4 of Embodiment 1 can be obtained.

[0461] Embodiment 1 Modification 6.

[0462] In this modification, a scheduling method that enables retransmission in the next subframe after receiving an Ack / Nack when performing asymmetric scheduling in a self - contained subframe will be described.

[0463] Since symmetric scheduling is used in the methods of Modification Example 2 to Modification Example 5 of Embodiment 1, retransmission data must be transmitted in the subframe next to the initial transmission. However, in the subframe next to the initial transmission, when the frequency resources are smaller than those of the initial transmission or the radio wave environment becomes worse than that of the initial transmission, even if the retransmission data is transmitted in the subframe next to the initial transmission, there is a problem that the possibility of becoming an Ack is low and the efficiency is low.

[0464] In this modification example, a method for solving the above problems is disclosed.

[0465] The eNB and the UE use asymmetric scheduling. In addition, before receiving an Ack / Nack from the UE, the eNB schedules the initial transmission data or the retransmission data to be transmitted in the next subframe.

[0466] The eNB determines whether to perform retransmission in the next subframe. The eNB transmits downlink control information to the UE at each retransmission. The UE receives the downlink control information from the eNB in each subframe. The UE receives the initial transmission data or the retransmission data according to the indication of the above downlink control information.

[0467] In this modification example, a HARQ process number may be included in the above downlink control information. Alternatively, an identifier indicating retransmission may also be included.

[0468] In this modification example, the following five (1) to (5) are disclosed as specific examples of the information required for the eNB to determine whether retransmission is possible.

[0469] (1) The number of available REs.

[0470] (2) Channel conditions.

[0471] (3) Coding rate of the retransmission data.

[0472] (4) Number of retransmissions.

[0473] (5) A combination of the above (1) to (4).

[0474] In the above (1), the presence or absence of a common signaling channel can be used. As the presence or absence of a common signaling channel, for example, the presence or absence of a synchronization channel can be used. Alternatively, the presence or absence of a physical broadcast channel can also be used.

[0475] In the above (2), as the channel condition, the CQI transmitted by the UE can be used. As the CQI, periodic CQI (Periodic CQI) or aperiodic CQI (Aperiodic CQI) can be used. In addition, the uplink reference signal transmitted by the UE can be used to obtain the channel condition in the eNB. As the above uplink reference signal, the uplink demodulation reference signal can be used, the uplink sounding reference signal can be used, or other uplink reference signals can be used.

[0476] In the above (3), a threshold can be set for the coding rate of the retransmitted data, and it can be determined whether retransmission is possible based on whether it is above or below the threshold. As the determination of whether retransmission is possible using the threshold of the coding rate, for example, it can be determined that retransmission is possible when the coding rate is 1 or less, that is, when the number of bits before coding is less than the number of bits after coding, or it can be based on other determination criteria.

[0477] As specific examples of the determination criteria used in the scheduling in the eNB in this modification example, the following four (1) to (4) are disclosed.

[0478] (1) Whether there are sufficient frequency resources for retransmission in the subframe to be scheduled.

[0479] (2) Whether the eNB has the data before coding for the initial transmission.

[0480] (3) Whether an Ack has been received from the UE.

[0481] (4) A combination of the above (1) to (3).

[0482] For the above (4), for example, scheduling can be performed in the order of the above (1), the above (2), and the above (3). Or, for example, scheduling can also be performed in the order of the above (3), the above (1), and the above (2).

[0483] As the timing for the determination of whether retransmission is possible performed by the eNB in this modification example, it can be set to be performed together with the scheduling of the retransmitted data by the eNB. For example, for whether the first retransmission can be sent, it can be performed when sending the initial transmission data from the eNB, and for whether the second retransmission can be sent, it can be performed when sending the first retransmitted data from the eNB.

[0484] In this modification example, among multiple DL data required for retransmission scheduling, scheduling of a part of the DL data including retransmission of the DL data that has been initially transmitted first can be performed. Alternatively, scheduling of a part of the DL data including retransmission of the DL data that has been recently initially transmitted or retransmitted can be performed. Alternatively, scheduling of multiple DL data required for retransmission can be performed, and when transmitting downlink user data, which DL data to transmit can be selected.

[0485] For this modification example, the same scheduling as in Modification Example 2 of Embodiment 1, in which the retransmission scheduling before n subframes is determined in advance, can be applied.

[0486] For this modification example, the same scheduling as in Modification Example 3 of Embodiment 1, in which retransmission is performed in the m subframes after the initial transmission, can be applied. The eNB can perform scheduling of a part of the DL data including retransmission of the DL data that has been initially transmitted first among multiple DL data required for retransmission scheduling. Alternatively, scheduling of a part of the DL data including retransmission of the DL data that has been just initially transmitted or retransmitted can be performed. Alternatively, scheduling of multiple DL data required for retransmission can be performed, and when transmitting downlink user data, which DL data to transmit can be selected.

[0487] Figure 31 and Figure 32 are diagrams showing an example of a method for performing scheduling one frame before in Modification Example 6 of Embodiment 1. In Figure 31 and Figure 32 , an example of scheduling (n = 1) for determining the retransmission scheduling of the next subframe in this modification example is shown. Figure 31 is connected to Figure 32 at the position of the boundary line BL11. In Figure 31 and Figure 32 , the horizontal axis represents time t, and the vertical axis represents frequency f.

[0488] In subframe #1, the eNB performs transmission of the initial transmission of DL data #1. In addition, since there is frequency resource for retransmitting DL data #1 in the next subframe #2, the eNB performs scheduling for retransmitting DL data #1 together with the scheduling for the initial transmission of DL data #2.

[0489] In Figure 31 and Figure 32 , an Ack is returned from the UE in subframe #1 shown, so the eNB performs transmission of the initial transmission of DL data #2 in subframe #2. However, since there is no frequency resource required for retransmitting DL data #2 in the next subframe #3, the eNB does not perform scheduling for retransmitting DL data #2 and only performs scheduling for the initial transmission of DL data #3.

[0490] Although a Nack was returned from the UE in subframe #2 shown in Figure 31 and Figure 32 only the scheduling for the first transmission of DL data #3 was completed in subframe #2. Therefore, the eNB performs the first transmission of DL data #3 in subframe #3.

[0491] Candidates for scheduling for the next subframe #4 are for retransmission of DL data #2, retransmission of DL data #3, and retransmission of DL data #4. In the next subframe #4, there are sufficient frequency resources for transmitting the retransmission of DL data #2 and the retransmission of DL data #3.

[0492] The eNB performs scheduling for retransmission of DL data #2, retransmission of DL data #3, and first transmission of DL data #4. The eNB can perform any one of the above three schedulings, or any two of the above three schedulings.

[0493] Since an Ack was returned from the UE in subframe #3 shown in Figure 31 and Figure 32 there is no need for scheduling for retransmission of DL data #3 at the end of subframe #3. The eNB selects the retransmission of DL data #2 with a smaller data number from the scheduling for retransmission of DL data #2 and the first transmission of DL data #4 and transmits it in subframe #4. It is also possible to select and transmit the first transmission of DL data #4.

[0494] Figure 33 and Figure 34 are diagrams showing an example of a method of scheduling one frame before in the case of performing one retransmission in Modification Example 6 of Embodiment 1. Figure 33 and Figure 34 show an example of scheduling (m = 1, n = 1) of the retransmission of the frame after the first transmission in this modification example. Figure 33 Connects to Figure 34 at the position of the boundary line BL12. In Figure 33 and Figure 34 the horizontal axis represents time t and the vertical axis represents frequency f.

[0495] In subframe #1, the eNB performs the first transmission of DL data #1. In addition, since there are frequency resources for performing the retransmission of DL data #1 in the next subframe #2, the eNB performs scheduling for retransmission of DL data #1.

[0496] In Figure 33 and Figure 34In subframe #2 shown, the eNB transmits a retransmission of DL data #1. In addition, since an Ack was returned from the UE in subframe #1, the eNB schedules for the initial transmission of DL data #2 in subframe #2.

[0497] In Figure 33 and Figure 34 In subframe #3 shown, the eNB transmits the initial transmission of DL data #2. However, since there are no frequency resources required for retransmitting DL data #2 in the next subframe #4, the eNB does not schedule for the retransmission of DL data #2, but schedules for the initial transmission of DL data #3.

[0498] In Figure 33 and Figure 34 In subframe #4 shown, the eNB transmits the initial transmission of DL data #3. In addition, since there are frequency resources for retransmitting DL data #3 in subframe #5, the eNB schedules for the retransmission of DL data #3.

[0499] In Figure 33 and Figure 34 In subframe #4 shown, since a Nack was returned from the UE in subframe #3, the eNB can schedule for the retransmission of DL data #2.

[0500] In Figure 33 and Figure 34 In subframe #5 shown, the eNB transmits a retransmission of DL data #3. In addition, since there are frequency resources for retransmitting DL data #2 in subframe #6, scheduling for the retransmission of DL data #2 is performed.

[0501] According to this modification example, in addition to the effects of Modification Example 2 of Embodiment 1 or Modification Example 3 of Embodiment 1, the following effects can also be obtained. Specifically, when the radio environment changes, user data communication can be performed efficiently.

[0502] Embodiment 1 Modification Example 7.

[0503] In this modification example, a scheduling method for aborting HARQ retransmissions in self - contained subframes will be described.

[0504] In the methods of Modification Example 2 to Modification Example 5 of Embodiment 1, when the situation where the frequency resources and modulation method change due to reasons such as deterioration of the radio environment during retransmission continues, no matter how many times retransmissions are performed, the UE cannot receive correctly, and the eNB will continue retransmissions until the maximum number of retransmissions is reached, which will cause waste in communication.

[0505] In addition, in the method of Modification Example 6 of Embodiment 1, when the above situation persists and the retransmission of data for the UE is not performed continuously, there is a problem of lack of user data.

[0506] In this modification example, a method for solving the above problems is disclosed.

[0507] The eNB determines whether to abort the retransmission of downlink data. Based on the above determination, the eNB aborts the retransmission of downlink user data.

[0508] The first transmitted data after aborting the retransmission of downlink user data may or may not include elements constituting the data for which the retransmission has been aborted. The above elements may be, for example, a protocol data unit (PDU) in the upper layer of HARQ, or MAC signaling information. The above upper layer may be, for example, the RLC layer.

[0509] The abort of retransmission in this modification example can be performed for each UE or for each HARQ process.

[0510] As information required for determining the abort of retransmission in this modification example, the following seven (1) to (7) are disclosed.

[0511] (1) The number of available resource elements (REs).

[0512] (2) Channel conditions.

[0513] (3) Update period of information indicating channel conditions.

[0514] (4) Coding rate of retransmitted data.

[0515] (5) Number of retransmissions.

[0516] (6) Maximum number of retransmissions.

[0517] (7) Combinations of the above (1) to (6).

[0518] In the above (1), the presence or absence of a common signaling channel can be used. As the presence or absence of a common signaling channel, for example, the presence or absence of a synchronization channel can be used. Alternatively, the presence or absence of a physical broadcast channel can also be used.

[0519] In the above (2), as the channel condition, the CQI transmitted by the UE can be used. As the CQI, periodic CQI (Periodic CQI) or aperiodic CQI (Aperiodic CQI) can be used. In addition, the uplink reference signal transmitted by the UE can be used to obtain the channel condition in the eNB. As the above uplink reference signal, the uplink demodulation reference signal can be used, the uplink sounding reference signal can be used, or other uplink reference signals can be used.

[0520] Regarding the above (3), for example, it can be the transmission period of the CQI. Or, it can be the transmission period of the uplink reference signal. Regarding the transmission period of the uplink reference signal, for example, it can be the transmission period of the uplink demodulation reference signal, the transmission period of the sounding reference signal, or the transmission period of other uplink reference signals.

[0521] In the above (4), a threshold can be set for the coding rate of the retransmitted data, and it can be determined whether retransmission is possible based on whether it is above or below the threshold. As the determination of whether retransmission is possible using the threshold of the coding rate, for example, it can be determined to abort retransmission when the coding rate is 1 or less, that is, when the number of bits before coding is less than the number of bits after coding, in a subframe that continues for a predetermined number of times, or it can be based on other judgment criteria.

[0522] In the above (1) to (6), not only the information of the subframe to be scheduled is used, but also the information up to several subframes before is used.

[0523] In this modification example, as the timing for determining the abort of retransmission, for example, it can be at the time of scheduling retransmission. Or, it can also be when the information indicating the channel condition in the above (2) is received.

[0524] In this modification example, for the determination of whether the structural element of the data that aborted retransmission is included in the first transmitted data after the abort of retransmission, the presence or absence of retransmission control in the upper layer of HARQ, such as the RLC layer, can be used. Or, the presence or absence of reordering (sorting) in the upper layer of HARQ can be used. Or, both can be used in combination.

[0525] As information for identifying whether or not there is the above retransmission control and whether or not there is the above reordering, for example, the mode of RLC can be used. For example, in the case of AM (Acknowledge Mode) of RLC, there is retransmission control and there is reordering. In addition, for example, in the case of UM (Unacknowledged Mode) of RLC, there is no retransmission control and there is reordering. In addition, for example, in the case of TM (Transparent Mode) of RLC, there is no retransmission control and there is no reordering.

[0526] In this modification example, the eNB can notify the UE of the cancellation of HARQ retransmission. In the notification of the cancellation of HARQ retransmission, a downlink control signal can be used. The downlink control signal can include an identifier indicating new data. The above identifier can use, for example, NDI (New Data Indicator). In addition, the downlink control signal can include the HARQ process ID. In addition, the downlink control signal can also include both the above identifier and the above process ID. For example, in the downlink control signal of the first transmission after the cancellation of retransmission, the eNB can include the process ID for which retransmission has been cancelled and the NDI indicating the first transmission. Alternatively, the MAC signaling can be used to notify the UE of the cancellation of HARQ retransmission.

[0527] In this modification example, the UE can determine whether or not the eNB has cancelled retransmission based on the downlink control signal from the eNB. For example, when the downlink control signal received from the eNB includes the HARQ process ID waiting for retransmission and the NDI indicating the first transmission, the UE determines that the retransmission in the process ID has been cancelled.

[0528] In this modification example, the MAC layer of the eNB can notify the upper layer of the cancellation of HARQ retransmission. The upper layer can be, for example, the RLC layer.

[0529] In this modification example, the MAC layer of the UE can notify the upper layer of the cancellation of HARQ retransmission. The upper layer can be, for example, the RLC layer. In addition, the MAC layer of the UE can also discard the HARQ received data that is the object of the cancellation of HARQ retransmission.

[0530] For this modification example, it can be applied to the same scheduling as in the modification example 2 of the first embodiment, in which the retransmission scheduling before n subframes is determined in advance.

[0531] For this modification example, the scheduling of retransmission that is the same as that in Modification Example 3 of Embodiment 1 can be applied, i.e., the retransmission is scheduled to be sent in the subsequent m subframes after the first transmission. Among the multiple DL data required for the scheduling of retransmission, the eNB can perform scheduling of a part of the DL data that includes the retransmission of the DL data that has been first transmitted. Alternatively, the eNB can also perform scheduling of a part of the DL data that includes the retransmission of the DL data that has just been first transmitted or retransmitted. Alternatively, the eNB can also perform scheduling of the multiple DL data required for retransmission and select which DL data to send when transmitting downlink user data.

[0532] Figure 35 And Figure 36 FIG. is an example diagram showing a method of performing scheduling one frame before in Modification Example 7 of Embodiment 1. In Figure 35 And Figure 36 an example of the scheduling (n = 1) for pre-determining the retransmission scheduling of the next subframe in this modification example is shown. Figure 35 Is connected to Figure 36 at the position of the boundary line BL13. In Figure 35 And Figure 36 the horizontal axis represents the time t and the vertical axis represents the frequency f.

[0533] In Figure 35 And Figure 36 in the scheduling shown, the MAC layer receives an RLC PDU from the upper RLC layer and generates data to be sent to the UE. In addition, it is assumed that there is insufficient frequency resource required to send the DL data before subframe #2 after subframe #3.

[0534] In Figure 35 And Figure 36 in subframe #1 shown, the eNB sends DL data #1 generated from RLC PDUs 1 to 3 to the UE as the first transmission. In addition, the eNB performs scheduling for retransmission of DL data #1 together with the scheduling for the first transmission of DL data #2. DL data #2 is data generated from RLC PDUs 4 to 6.

[0535] In Figure 35 And Figure 36An Ack was returned from the UE in subframe #1 shown below. Therefore, the eNB transmits the initial transmission of DL data #2 in subframe #2. However, there is no resource for transmitting DL data #2 after the next subframe #3. Therefore, the eNB aborts the retransmission of DL data #2. The eNB schedules for the initial transmission of DL data #4 to prepare for the arrival of an Ack from the UE. In addition, the eNB schedules for the initial transmission of DL data #3 to prepare for the arrival of a Nack from the UE. Here, DL data #4 is data generated from RLC PDUs 7 and 8 that are not included in DL data #2. DL data #3 is data generated from RLC PDUs #4 and 5 that are also included in DL data #2. In the scheduling in subframe #2, the eNB may not schedule for the initial transmission of DL data #3.

[0536] In Figure 35 and Figure 36 A Nack was returned from the UE in subframe #2 shown below. Therefore, the eNB transmits the initial transmission of DL data #3 in subframe #3. In addition, the eNB schedules for the initial transmission of DL data #5 and for the retransmission of DL data #3.

[0537] In Figure 35 and Figure 36 An Ack was returned from the UE in subframe #3 shown below. Therefore, the eNB transmits the initial transmission of DL data #5 in subframe #4. In addition, the eNB schedules for the initial transmission of DL data #6 and for the retransmission of DL data #5.

[0538] Figure 37 and Figure 38 are diagrams showing an example of a method for scheduling one frame before in the case of performing one retransmission in Modification 7 of Embodiment 1. Figure 37 and Figure 38 show an example of the scheduling (m = 1, n = 1) of the retransmission of the subsequent subframe equivalent to the initial transmission in this modification. Figure 37 Connects to Figure 38 at the position of the boundary line BL14. In Figure 37 and Figure 38 the horizontal axis represents time t and the vertical axis represents frequency f.

[0539] In Figure 37 and Figure 38 shown in the scheduling below, the MAC layer receives RLC PDUs from the upper RLC layer and generates data to be transmitted to the UE. In addition, it is assumed that there is insufficient frequency resource for transmitting the DL data before subframe #3 after subframe #4.

[0540] In Figure 37 and Figure 38In subframe #1 shown, the eNB transmits DL data #1 generated from RLC PDUs 1 to 3 to the UE as the initial transmission. In addition, the eNB performs scheduling for retransmission of DL data #1.

[0541] In Figure 37 and [[ID= In subframe #2 shown, the eNB transmits the retransmission of DL data #1. In addition, since an Ack is returned from the UE in subframe #1, the eNB performs scheduling for the initial transmission of DL data #2. DL data #2 is data generated from RLC PDUs 4 to 6.

[0542] In ​ and ​ In subframe #3 shown, the eNB transmits the initial transmission of DL data #2. However, there is no resource for transmitting DL data #2 after the next subframe #4, so the eNB aborts the retransmission of DL data #2. The eNB performs scheduling for the initial transmission of DL data #2a. DL data #2a is data generated from RLC PDUs #4 and 5 that are also included in DL data #2. The eNB can also schedule the transmission of data after RLC PDU 7 that is not included in DL data #2 instead of DL data #2a.

[0543] In ​ and ​ In subframe #4 shown, the eNB transmits the initial transmission of DL data #2a. In addition, since an Ack is returned from the UE for DL data #2, the eNB performs scheduling for the initial transmission of DL data #3. The eNB can schedule the retransmission of DL data #2a regardless of whether an Ack for DL data #2 is received from the UE.

[0544] Regarding ​ and ​ After subframe #5 shown, since the actions become the same as those in ​ and ​ the description is omitted.

[0545] The scheduling method shown in this modification example can be applied to the scheduling of the uplink. The entity that determines the abort of the retransmission of uplink user data can be the eNB or the UE. The eNB can notify the UE of the abort of the retransmission of uplink user data. In the notification of the abort of the retransmission to the UE, L1 / L2 signaling or MAC signaling can be used. The UE can notify the eNB of the abort of the retransmission of uplink user data. In the notification of the abort of the retransmission to the eNB, L1 / L2 signaling or MAC signaling can be used.

[0546] According to this modification example, in addition to the effects of Modification Example 2 of Embodiment 1 or Modification Example 3 of Embodiment 1, the following effects can also be obtained. Specifically, it is possible to prevent duplication of retransmission when the wireless environment deteriorates, and user data communication can be performed efficiently.

[0547] Embodiment 1 Modification Example 8.

[0548] In this modification example, other methods for reducing or eliminating the interval length after transmission of the uplink signal in a self - contained subframe will be described.

[0549] If the interval length after transmission of the uplink signal is reduced or eliminated in a self - contained subframe, the following problem will occur: the transmission timing of the scheduling information of this subframe will not catch up with the transmission timing of the downlink control information of the next subframe.

[0550] In this modification example, a method for solving the above - mentioned problem is disclosed.

[0551] The eNB configures the scheduling information in the user data area.

[0552] When configuring in the above - mentioned user data area, the eNB can apply the structure of EPDCCH (Enhanced Physical Downlink Control Channel). In addition, at the timing of transmitting the downlink control information, the eNB can decode the Ack / Nack from the UE. In addition, the eNB can also perform scheduling for the next subframe. In addition, the eNB can also encode the user data to be transmitted in the next subframe.

[0553] The UE can receive the area of the EPDCCH for each subframe.

[0554] The eNB only needs to notify the UE of the information related to the above - mentioned EPDCCH structure. In the notification of the above - mentioned information, RRC dedicated signaling, MAC signaling, or L1 / L2 signaling can be used. The above - mentioned L1 / L2 signaling can be transmitted using PDCCH.

[0555] The eNB and the UE can apply the scheduling method shown in this modification example to both symmetric and asymmetric scheduling. In addition, it can also be applied to both adaptive scheduling and non - adaptive scheduling.

[0556] According to this modification example, the interval after transmission of the uplink signal can be reduced or eliminated. Therefore, it is possible to achieve the high - efficiency of communication between the eNB and the UE.

[0557] Embodiment 2.

[0558] The following situation is discussed, i.e., in the case of Time Division Duplex (TDD), by utilizing the reversibility of the channel, the Sounding Reference Signal (SRS) transmitted in the uplink is used in deriving the precoding weights for downlink MIMO. Although periodic SRS (Periodic Sounding Reference Signal) is supported in LTE, in order to change the transmission period of the periodic SRS, it is necessary to change the setting using RRC dedicated signaling (refer to 3GPP TS 36.331 V13.2.0 (hereinafter referred to as "Reference 3")).

[0559] However, when the moving speed of the UE changes significantly within a short period of time, the required transmission period of the SRS will be different according to the Doppler frequency change. In such a case, if RRC dedicated signaling is used for changing the transmission period of the SRS, it becomes difficult to respond in a short time and the precoding performance deteriorates. In addition, in the case where the radio wave transmission environment changes suddenly and the traffic changes suddenly, if RRC dedicated signaling is used for changing the transmission period of the SRS, it also becomes difficult to respond in a short time and the precoding performance also deteriorates.

[0560] Therefore, in the existing method for changing the transmission period of the SRS, it is impossible to change the period setting of the SRS within a short time and it is impossible to transmit the SRS when needed. As a result, there is a problem that the precoding performance for downlink MIMO deteriorates.

[0561] In this embodiment, a method for solving the above problems is disclosed.

[0562] The period in which the UE actually periodically transmits the SRS (hereinafter sometimes referred to as the "SRS transmission period") is set as L1 / L2 control information. As the SRS transmission period, for example, it is set as information representing the value of the SRS transmission period. The cell notifies the UE of the SRS transmission period using L1 / L2 control signaling. The cell can notify the SRS transmission period as downlink control information (DCI) transmitted using downlink L1 / L2 control signaling. The cell can also map the SRS transmission period to the downlink physical control channel for notification.

[0563] The cell can notify the UE of the SRS transmission period, thereby starting the periodic SRS transmission. The UE can start the transmission of the periodic SRS when it receives the SRS transmission period from the cell. The UE starts the transmission of the periodic SRS after the period change at the timing of the earliest subframe in which the SRS can be transmitted since the moment it receives the SRS transmission period from the cell.

[0564] The UE can set the information for stopping SRS transmission. It can be set separately from the SRS transmission period, or can be set as one value of the SRS transmission period. For example, 0 can be set as the value of the SRS transmission period, and SRS transmission is stopped when 0 is set. The UE stops SRS transmission when the value of the SRS transmission period is 0.

[0565] The subframes for actually transmitting SRS are set as part or all of the subframes capable of SRS transmission. The cell can pre-set the subframe structure capable of SRS transmission for the UE individually. For example, the cell individually sets for the UE the subframe period capable of SRS transmission (hereinafter sometimes referred to as "SRS transmittable period"), frequency band, subcarrier spacing (comb value), CS (Cyclic Shift), etc. The subframe structure capable of SRS transmission is transmitted using RRC signaling. The cell can set the subframe structure capable of SRS transmission for each UE taking into account the multiplexing between the SRSs of multiple UEs.

[0566] The subframes for actually transmitting SRS are set as part or all of the subframes capable of SRS transmission. Thus, the subframe structure other than the SRS transmission period of the subframes for actually transmitting SRS is set to be the same as the subframe structure capable of SRS transmission.

[0567] Thus, by setting the subframes for actually transmitting SRS as part or all of the subframes capable of SRS transmission for each UE taking into account the multiplexing between the SRSs of multiple UEs, even if the SRS transmission period is changed, multiplexing with the SRSs of other UEs can be performed without problems.

[0568] ​ It is a diagram for explaining the method of setting the SRS transmission period in Embodiment 2. In ​ the horizontal axis represents time t. Allowable subframe represents the subframes capable of SRS transmission set for each cell. Configured Subframe represents the subframes capable of SRS transmission for each UE set for each UE. The Configured Subframe is set within the subframes capable of SRS transmission set for each cell. Transmission subframe represents the subframes for actually transmitting SRS. The subframes for actually transmitting SRS are set as part or all of the subframes capable of SRS transmission for each UE.

[0569] ​Among them, permitted subframes are shown by boxes without shading, configured subframes are shown by diagonal shading with a solid line slanting left downwards, and transmission subframes are shown by diagonal shading with a solid line slanting right downwards. In addition, the SRS transmission period notification from the cell to the UE is shown by diagonal shading with a dashed line slanting right downwards.

[0570] The subframe structure capable of SRS transmission for each cell is broadcast by the cell to the UE. Here, it is notified using System Information (SI). As the subframe structure capable of SRS transmission for each cell, there is a subframe period capable of SRS transmission for each cell. The subframe structure capable of SRS transmission for each UE can be notified by the cell to the UE using UE-specific signaling. Here, it is notified using RRC-specific signaling. As the structure of the subframe capable of SRS transmission for each UE, there is a subframe period capable of SRS transmission for each UE.

[0571] As one of the DCIs, the period of the SRS actually transmitted by the UE, that is, the SRS transmission period, is set. The cell sets the SRS transmission period so that it is included in the DCI to be mapped to the physical dedicated control channel and notifies the UE. Here, the physical dedicated control channel is equivalent to the PDCCH in LTE. The UE starts transmitting the SRS from the subframe capable of SRS transmission for each UE at the earliest timing after receiving the SRS transmission period, with the SRS transmission period. The cell starts receiving the SRS transmitted from the UE from the subframe capable of SRS transmission for each UE at the earliest timing after notifying the SRS transmission period for the UE, with the SRS transmission period.

[0572] In ​ the eNB notifies the UE of the subframe structure capable of SRS transmission for each UE. As another method, the eNB may not notify the UE of the subframe structure capable of SRS transmission for each UE. The eNB may notify the UE of the subframe structure capable of SRS transmission for each cell. The eNB may also notify the UE of the subframe structure for actually transmitting the SRS.

[0573] The above subframe structure for actually transmitting the SRS can be notified using MAC signaling or L1 / L2 signaling. The UE can start transmitting the SRS from the subframe capable of SRS transmission for each cell at the earliest timing after receiving the SRS transmission period, with the SRS transmission period. Thus, the notification of the subframe structure capable of SRS transmission for each UE can be omitted, so that the signaling amount can be reduced and efficient communication can be performed.

[0574] As another method, the eNB may not notify the UE of the subframe structure in which SRS transmission for each cell can be performed. The eNB may notify the UE of the subframe structure in which SRS transmission for each UE can be performed. The eNB may also notify the UE of the subframe structure in which SRS is actually transmitted.

[0575] The above-mentioned subframe structure in which SRS is actually transmitted can be notified using MAC signaling or L1 / L2 control signaling. The UE may start SRS transmission from the subframe in which SRS transmission for each UE can be performed at the earliest timing after receiving the SRS transmission period. Thus, the notification of the subframe structure in which SRS transmission for each cell can be performed can be omitted, so that the signaling amount can be reduced and efficient communication can be performed.

[0576] As another method, the eNB may notify only the subframe structure in which SRS is actually transmitted to the UE. The eNB may successively determine the subframe structure in which SRS is actually transmitted to this UE in consideration of the multiplexing of SRS with other UEs. The above-mentioned subframe structure may be periodic or aperiodic. The notification of the above-mentioned subframe structure may use L1 / L2 signaling. Thus, the SRS transmission timing for each UE can be flexibly changed.

[0577] As described above, as the structure of the subframe, there are the period of the subframe, frequency band, subcarrier spacing (comb value), CS (Cyclic Shift), etc. There may be multiple frequency bands. The frequency band may be in units of resource blocks or may also be in units of subcarriers. In addition, the number of SRS transmission symbols, SRS transmission symbols, sequence identifier of SRS, frequency hopping pattern of SRS, sequence hopping pattern of SRS, etc. may be included in the subframe structure. One or more of these elements may also be combined and adopted in the subframe structure.

[0578] The number of consecutive SRS transmission symbols and the first SRS transmission symbol may also be included in the subframe structure. In 3GPP, a method in which the UE transmits SRS using multiple consecutive symbols has been investigated. For example, by notifying this information as the subframe structure in this case, the information of the SRS transmission symbols corresponding to the number of SRS transmission symbols does not need to be notified. The amount of information required for notification can be reduced.

[0579] In addition, the frequency band, etc. of each SRS symbol may be included. Elements of other subframe structures may be included in each SRS symbol. This is effective when the frequency band, etc. is different for each SRS symbol.

[0580] A table representing the correspondence relationship can be set for the information on the subframe structure. The cell notifies the UE of one or more pieces of information in the subframe structure information. The UE uses this table to derive other information from the notified one or more pieces of information. For example, a table representing the correspondence relationship between the SRS transmission period and the SRS transmission band is preset, and the cell notifies the UE of the SRS transmission period. The UE that receives the SRS transmission period uses this table to derive the SRS transmission band.

[0581] Thus, the UE sets the subframe structure derived by using one or more pieces of information in the subframe structure information notified from the cell and this table. The UE transmits the SRS according to the derived subframe structure. The table showing the correspondence relationship of the subframe structure information can be determined in advance statically through standards or the like, or can be notified to the UE from the cell in a semi-static manner. RRC signaling can be used in the semi-static notification.

[0582] Thus, the cell does not need to explicitly show the information that can be derived by using the table in the UE. Other information is implicitly notified. The information notified to the UE can be reduced.

[0583] ​ In the method shown, the transmission of the periodic SRS is started by the cell notifying the UE of the SRS transmission period. As another method, information for starting the transmission of the periodic SRS can be set separately. The transmission of the periodic SRS is started by the cell notifying the UE of the information for starting the transmission of the periodic SRS. The UE can start the transmission of the periodic SRS when it receives the information for starting the transmission of the periodic SRS from the cell. The UE starts the transmission of the periodic SRS after the period change at the earliest subframe timing when it can perform SRS transmission after receiving the information for starting the transmission of the periodic SRS from the cell.

[0584] The cell can notify the UE of the SRS transmission period together with the information for starting the transmission of the periodic SRS. Together with the information for starting the transmission of the periodic SRS, the UE starts the transmission of the periodic SRS with the received SRS transmission period.

[0585] The cell can notify the UE of the SRS transmission period and the information for starting the transmission of the periodic SRS separately. In this case, the UE can set the initial value of the SRS transmission period to the SRS transmissible period. Before the cell notifies the UE of the SRS transmission period separately, the UE sets the preset SRS transmissible period as the SRS transmission period and starts the transmission of the periodic SRS. When the cell notifies the UE of the SRS transmission period separately, the UE sets this SRS transmission period as the transmission period of the periodic SRS.

[0586] Thus, the start of the transmission of the periodic SRS can be set independently of the setting of the SRS transmission period. Therefore, the start of the transmission of the periodic SRS can be flexibly performed according to the radio wave transmission environment or the like.

[0587] In addition, as another method, information for starting the transmission of the periodic SRS may not be provided. The cell can start the transmission of the periodic SRS by notifying the UE of the subframe structure in which the SRS can be transmitted. In this case, the UE may simply set the initial value of the SRS transmission period to the SRS transmittable period. Before the cell notifies the UE of the SRS transmission period separately, the UE sets the preset SRS transmittable period as the SRS transmission period and starts the transmission of the periodic SRS. When the cell notifies the UE of the SRS transmission period separately, the UE sets this SRS transmission period as the transmission period of the periodic SRS.

[0588] Thus, when it is desired to change the SRS transmission period, the cell only needs to notify the UE of the SRS transmission period by the L1 / L2 control signal, and the amount of information required for the notification can be reduced.

[0589] In the above method, as the SRS transmission period, information representing the value of the SRS transmission period is used. Here, an example of another setting method of the SRS transmission period is shown. For example, the period of the subframe in which the SRS of each UE can be transmitted, that is, the SRS transmittable period, is set as the basic period, and the SRS transmission period is set to n times (n is a positive integer) of this basic period. Thus, the subframe actually transmitting the SRS can be set within the subframe in which the SRS can be transmitted.

[0590] As the amount of information representing the SRS transmission period, the amount of information representing the value of n is sufficient. Thus, the amount of information can be made smaller than in the case of directly representing the value of the SRS transmission period. The amount of information notified from the cell to the UE can be reduced. In addition, n = 0 may be added, and in the case of n = 0, the SRS transmission is set to stop.

[0591] As an example of another setting method, it can be set to 2 to the (n - 1)th power (n is a positive integer) times the basic period. Thus, the subframe actually transmitting the SRS can be set within the subframe in which the SRS can be transmitted. Compared with the case of setting it to n times the basic period, the period can be changed significantly with the same amount of information. In addition, n = 0 may be added, and in the case of n = 0, the SRS transmission is set to stop. Alternatively, it can also be set to 2 to the nth power (n is an integer of 0 or more) times the basic period. In this case, the SRS transmission can be set to stop when all bits representing n are 1.

[0592] When SRS transmission is stopped, set n = 0, but it can also be set to another specific value of n. For example, it can be set to the case where all bits representing n are 1. The value for stopping SRS transmission can be determined in advance by standards or the like, so that both the cell and the UE can recognize the stop of SRS transmission.

[0593] An example of another setting method is disclosed. Set up a table that attaches numbers to SRS transmission periods as indices. It can be determined in advance by standards or the like. Alternatively, it can be broadcast from the cell to the UE, or it can be notified to the UE using RRC dedicated signaling. Set the information representing the SRS transmission period as this number. The cell selects an SRS transmission period from this table and notifies the UE of the number attached to the selected SRS transmission period. The UE derives the SRS transmission period from the received number and the table and sets it as the transmission period of periodic SRS.

[0594] In this way, any SRS transmission period can be set. In addition, by reducing it to the required amount, the amount of information can be reduced.

[0595] An example of another setting method for the SRS transmission period is shown. Set the information indicating the increase or decrease based on the currently set SRS transmission period. The initial value of the SRS transmission period can be set to the SRS transmittable period. Set the currently set SRS transmission period to be 1 time in every a SRS transmittable subframes. When the SRS transmission period increases, extend the SRS transmission period to be 1 time in every a + 1 SRS transmittable subframes. When the SRS transmission period decreases, shorten the SRS transmission period to be 1 time in every a - 1 SRS transmittable subframes.

[0596] It is only necessary to determine the maximum set value and the minimum set value of the SRS transmission period in advance. Even if the setting becomes larger than the maximum set value according to the increase or decrease information of the SRS transmission period, the maximum set value can be kept unchanged. Similarly, even if the setting becomes smaller than the minimum set value, the minimum set value can be kept unchanged. The minimum set value can be set to the SRS transmittable period. The maximum set value and the minimum set value of the SRS transmission period can be determined in advance by standards or the like, or can be notified from the cell to the UE.

[0597] As another setting method for the SRS transmission period, by setting the information indicating the increase or decrease based on the currently set SRS transmission period, the amount of information can be set to 1 bit, and the amount of information notified from the cell to the UE can be further reduced.

[0598] The offset value of the SRS subframe actually transmitted (hereinafter sometimes referred to as "SRS transmission offset value") can be set separately from the SRS transmission period. For example, the SRS transmission offset value can be time. For example, the SRS transmission offset value can be set to the number of SRS transmittable subframes from after the setting of the SRS transmission period until the start of the periodic SRS transmission. For example, when the cell sets the SRS transmission offset value to 3, the UE starts the periodic SRS transmission in the 3rd SRS transmittable subframe after receiving the SRS transmission period setting.

[0599] The cell can notify the UE of the offset information of the SRS subframe actually transmitted (hereinafter sometimes referred to as "SRS transmission offset information") together with the SRS transmission period. The UE starts the periodic SRS transmission based on the received SRS transmission period and SRS transmission offset information.

[0600] Alternatively, the cell can notify the UE of the SRS transmission offset information separately from the SRS transmission period. The UE can set the initial value of the SRS transmission offset to the offset from after receiving the SRS transmission period until the earliest subframe capable of SRS transmission. When the cell separately notifies the UE of the SRS transmission offset value, the UE re-sets the transmission subframe of the periodic SRS using the received SRS transmission offset value. Thus, by setting the offset value, the cell can flexibly set the start timing of the periodic SRS transmission.

[0601] As the above offset information, the remainder obtained by dividing the subframe number transmitting the SRS by the SRS transmission period can be used. Thus, a unique offset can be specified for the UE, regardless of the notification timing of the SRS transmission period from the cell to the UE.

[0602] When the cell notifies the UE of the above offset information together with the information for stopping the above periodic SRS transmission, the above offset information becomes the SRS transmission time or the number of SRS transmittable subframes from after the SRS transmission stop information setting until the stop of the periodic SRS transmission. The UE stops the periodic SRS transmission after the above offset information has elapsed since receiving the information for stopping the SRS transmission.

[0603] The offset information, which is the information for starting the SRS transmission, and the offset information, which is the information for stopping the SRS transmission, can be set as different parameters. The cell sets and notifies the UE with different parameters. The UE can identify whether the offset information is for starting the SRS transmission or for stopping the SRS transmission.

[0604] ​ It is a diagram for explaining the method of periodic SRS transmission when the SRS transmission offset is set together with the SRS transmission period.​ is similar to ​ , so mainly the different parts will be described. In ​ , the horizontal axis represents the time t.

[0605] ​ is a diagram for explaining the method of transmitting a periodic SRS with an SRS transmission period that is the same as the SRS transmission period of each UE. To change the period of the periodic SRS, the cell includes the changed SRS transmission period in the DCI and maps it to the physical control channel to notify the UE. In addition, the cell includes the SRS transmission offset in the DCI and notifies it to the UE together with the SRS transmission period.

[0606] ​ is a diagram for explaining the method of transmitting a periodic SRS after changing the SRS period when the SRS transmission offset value is set to 1. The cell sets the SRS transmission period for the UE and sets 1 as the SRS transmission offset value. The UE that receives the SRS transmission period and the SRS transmission offset value from the cell changes to the SRS transmission period set from the first SRS transmittable subframe after the setting of the SRS transmission offset and starts transmitting the periodic SRS.

[0607] ​ is a diagram for explaining the method of transmitting a periodic SRS after changing the SRS period when the SRS transmission offset value is set to 2. The cell sets the SRS transmission period for the UE and sets 2 as the SRS transmission offset value. The UE that receives the SRS transmission period and the SRS transmission offset value from the cell changes to the SRS transmission period set from the second SRS transmittable subframe after the setting of the SRS transmission offset and starts transmitting the periodic SRS.

[0608] Thus, the cell can set different offset values for each UE with the same SRS transmission period. By setting in this way, different SRS transmission subframes can also be set for each UE. In addition, it is possible to flexibly set the SRS transmission timing suitable for each UE for multiple UEs.

[0609] As a specific example of the determination index for changing the SRS transmission period, the following seven (1) to (7) are disclosed.

[0610] (1) Channel quality information of the UE.

[0611] (2) Moving speed of the UE.

[0612] (3) Acceleration (speed change) of the UE.

[0613] (4) Rotation speed of the UE.

[0614] (5) Rotational acceleration (change in rotational speed) of the UE.

[0615] (6) The multiplexing number of the UE.

[0616] (7) Combinations of the above (1) to (6).

[0617] In the case where the channel quality information of the UE in the above (1) is used as a judgment index, for example, when the channel quality is poor, the SRS transmission period is set shorter, and when the channel quality is good, the SRS transmission period is set longer. When the channel quality is poor, the UE transmits SRS to the cell at a shorter period. Thus, the cell can improve the SRS reception probability. In addition, the cell can reflect the situation of poor channel quality in the derivation of precoding weights with low latency. Therefore, the precoding performance can be improved.

[0618] In the case where the moving speed of the UE in the above (2) is used as a judgment index, for example, when the moving speed is fast, the SRS transmission period is set shorter, and when the moving speed is slow, the SRS transmission period is set longer. When the moving speed is fast, the UE transmits SRS to the cell at a shorter period, and the cell receives SRS at a shorter period. Thus, the influence of the Doppler frequency caused by the moving speed of the UE can be reduced. Therefore, the accuracy of SRS can be improved, and the precoding performance can be improved.

[0619] In the case where the acceleration (speed change) of the UE in the above (3) is used as a judgment index, for example, when the acceleration is large, the SRS transmission period is set shorter, and when the acceleration is small, the SRS transmission period is set longer. When the acceleration is large, the UE transmits SRS to the cell at a shorter period, and the cell receives SRS at a shorter period. Thus, the change in the moving speed of the UE can be reflected earlier. Therefore, the precoding performance can be improved.

[0620] In the case where the rotational speed of the UE in the above (4) is used as a judgment index, for example, when the rotational speed is large, the SRS transmission period is set shorter, and when the rotational speed is small, the SRS transmission period is set longer. When the rotational speed is large, the UE transmits SRS to the cell at a shorter period, and the cell receives SRS at a shorter period. Thus, the rotation of the UE can be reflected earlier. Therefore, the precoding performance can be improved.

[0621] When the rotational acceleration (change in rotational speed) of the UE in (5) above is used as a judgment criterion, for example, when the rotational acceleration is large, the SRS transmission period is set to be short, and when the rotational acceleration is small, the SRS transmission period is set to be long. When the rotational acceleration is large, the UE transmits the SRS to the cell at a short period, and the cell receives the SRS at a short period. Thus, the change in the rotational speed of the UE can be reflected earlier. Therefore, the precoding performance can be improved.

[0622] When the multiplexing number of the UE in (6) above is used as a judgment criterion, for example, when the multiplexing number of the UE is large, the SRS transmission period is set to be short, and when the multiplexing number of the UE is small, the SRS transmission period is set to be long. When the multiplexing number of the UE in MIMO is large, the UE transmits the SRS to the cell at a short period, and the cell receives the SRS at a short period. Thus, the accuracy of the SRS for each UE can be improved. Therefore, even when the multiplexing number of the UE is large, precoding weights with higher accuracy can be derived, and the precoding performance can be improved.

[0623] The cell acquires information related to the judgment criterion for changing the SRS transmission period. The cell can perform measurements or acquire the information from the UE. It can be appropriately determined for each piece of information related to the judgment criterion which one to use. For example, in the above examples of the judgment criterion, (1) and (6) above can be measured by the cell, and (2) to (5) above can be measured by the UE.

[0624] When acquiring the information from the UE, the UE measures the information related to the judgment criterion and notifies it to the cell. As a notification method, RRC signaling can be used. Alternatively, as a notification method, MAC signaling can also be used. It can be included in the MAC control information and notified using MAC signaling. Compared with the case of using RRC signaling, the cell can acquire the information related to the judgment criterion measured by the UE earlier.

[0625] Alternatively, as a notification method, L1 / L2 control signaling can be used. It can be included in the uplink L1 / L2 control information (UCI) and notified using L1 / L2 control signaling. Compared with the case of using MAC signaling, the cell can acquire the information related to the judgment criterion measured by the UE even earlier.

[0626] If the information related to the judgment criterion is set to its measured value, the amount of information becomes large. A table of the range of the measured value and an index provided for the range can be generated. The table can be statically determined in advance using standards or the like. As the information related to the judgment criterion, the index can be set. By using the index, the information related to the judgment criterion can be set to a smaller amount of information. It is better that the amount of information carried in the MAC control information or the L1 / L2 control information is smaller. Therefore, using the index in the above is effective.

[0627] ​ This is a diagram showing an example of the process for setting the SRS transmission period in Embodiment 2. ​ In the example shown, a method for starting or changing periodic SRS transmission by setting the SRS transmission period for each UE is disclosed.

[0628] In step ST3301, the cell includes the subframe structure capable of SRS transmission for each cell in the SIB and broadcasts it to the UEs within the coverage area.

[0629] In step ST3302, the cell decides the subframe structure capable of SRS transmission for each UE, taking into account the multiplexing between the SRSs of multiple UEs for which the SRS is set. The cell may also decide the SRS transmission period for each UE.

[0630] In step ST3303, the cell notifies the UE of the subframe structure capable of SRS transmission for each UE. This notification may use RRC dedicated signaling. In this notification, the UE does not start the transmission of periodic SRS.

[0631] In step ST3304, the cell decides the start of the transmission of periodic SRS for each UE.

[0632] In step ST3305, the cell sets the SRS transmission period and the SRS transmission offset value for the UE for which the start of the transmission of periodic SRS has been decided. In the above settings, as the initial value, the SRS transmission period can be set to the SRS transmissible period, and the SRS transmission offset value can be set to 1. The UE performs periodic SRS transmission in the subframe capable of SRS transmission for each UE.

[0633] In step ST3306, the cell notifies the UE for which the start of the transmission of periodic SRS has been decided of the SRS transmission period and the SRS transmission offset value. These pieces of information can be included in the DCI as L1 / L2 control information and notified using L1 / L2 signaling. Thus, the cell can notify the SRS transmission period and the SRS transmission offset value to the UE as early as possible after setting the SRS transmission period and the SRS transmission offset value.

[0634] The UE that has received the SRS transmission period and the SRS transmission offset value in step ST3306 derives the subframe for transmitting the SRS in step ST3307 based on the received SRS transmission period and SRS transmission offset value.

[0635] In step ST3308, the UE starts the transmission of periodic SRS in the subframe derived in step ST3307.

[0636] In step ST3309, the cell determines whether to change at least one of the SRS transmission period and the SRS transmission offset value for a UE that has started periodic SRS transmission. In this determination, a determination index for changing the above SRS transmission period is used.

[0637] When it is determined in step ST3309 that at least one of the SRS transmission period and the SRS transmission offset value needs to be changed, the process returns to step ST3305, and at least one of the SRS transmission period and the SRS transmission offset value for each UE is set. In the above setting, the determination index for changing the above SRS transmission period is used to derive the degree of change required, and at least one of the SRS transmission period and the SRS transmission offset value can be set.

[0638] In step ST3309, in addition to determining whether to change at least one of the SRS transmission period and the SRS transmission offset value, the cell can also determine whether to stop the periodic SRS transmission.

[0639] When it is determined to stop the periodic SRS transmission, the process returns to step ST3305, and the SRS transmission period of each UE is set to stop the periodic SRS transmission.

[0640] In step ST3309, a cell that determines not to stop the periodic SRS transmission and does not need to change the SRS transmission period and the SRS transmission offset value continues to receive the periodic SRS with the same settings. Since no change or stop of the periodic SRS is notified, the UE continues to transmit the periodic SRS with the same settings.

[0641] In the second embodiment, the UE can stop the SRS transmission according to the information for stopping the SRS transmission. Therefore, the timing of sending the information for stopping the SRS transmission to the UE can be after the timing of sending the information for starting the SRS to the UE. For example, the offset information that determines the period for stopping the above SRS transmission can be notified to the UE together with the information for starting the SRS transmission. For example, the offset information that determines the period for stopping the SRS transmission can be sent according to the timing at which the UE is desired to stop the SRS transmission. The UE stops the SRS transmission according to the offset information that determines the period for stopping the received SRS transmission.

[0642] By sending the offset information that determines the period for stopping the SRS transmission together with the information for starting the SRS transmission, the UE can stop the SRS transmission after this period from the start of the SRS transmission. There is no need to separately notify the information for stopping the SRS transmission.

[0643] As disclosed in this embodiment, when setting and changing the SRS transmission period, the SRS transmission period is set as L1 / L2 control information and notified by L1 / L2 control signaling. Thus, compared with the change using the existing RRC signaling, the notification can be performed within a short period. The time from when the cell determines to change at least one of the SRS transmission period and the SRS transmission offset value until the UE transmits the periodic SRS with the changed setting can be shortened to be shorter than the existing situation.

[0644] Therefore, the delay time in the SRS period setting can be reduced, and thus the UE can transmit the SRS when necessary. Thereby, the precoding performance for downlink MIMO can be improved.

[0645] As described above, the subframe structure for actually transmitting the SRS can be notified by MAC signaling or L1 / L2 control signaling. The subframe structure for actually transmitting other SRSs can also be notified together with the transmission period of the subframe for actually transmitting the SRS. The subframe structure for actually transmitting the SRS can also be notified together with the information for starting the SRS transmission.

[0646] Multiple subframe structures capable of SRS transmission for each cell can be set. In addition, multiple subframe structures capable of SRS transmission for each UE can also be set. One subframe structure capable of SRS transmission for each UE is selected from the multiple subframe structures capable of SRS transmission for each UE, and the subframe structure for actually transmitting the SRS for each UE is set so as to be part or all of the selected subframe structure capable of SRS transmission for each UE.

[0647] In addition, for example, one subframe structure capable of SRS transmission for each cell is selected from the multiple subframe structures capable of SRS transmission for each cell, and part or all of the selected subframe structure is applied to the subframe structure for actually transmitting the SRS for each UE. These are appropriately set according to the above setting methods, such as whether to set it so that the eNB only notifies the subframe structure for actually transmitting the SRS to the UE.

[0648] Thereby, the mode of the subframe structure for actually transmitting the SRS for each UE increases. Therefore, the SRS can be transmitted more appropriately according to the moving speed of the UE and the radio wave propagation environment.

[0649] ​This is a diagram showing an example of the SRS transmission procedure in the case where multiple subframes capable of SRS transmission are configured. In step ST6201, the cell configures multiple subframe structures capable of SRS transmission for each cell and notifies the UE of this configuration. The cell may notify the information on the configured subframe structure as system information. In step ST6202, the cell determines multiple SRS structures for each UE. In step ST6203, the cell notifies the UE of the determined multiple subframe structures capable of SRS transmission for each UE. This notification can be carried out using UE-specific RRC signaling.

[0650] In step ST6204, in order to enable the UE to actually transmit SRS, one is selected from the multiple subframe structures capable of SRS transmission for each UE. In step ST6205, the cell notifies the UE of the selected SRS transmission subframe structure. Here, in step ST6203 above, identifiers can be assigned to the subframe structures capable of SRS transmission for each UE, or these identifiers can be transmitted. In this case, in step ST6205, the cell may notify the UE of the identifier of the selected SRS-transmissible subframe structure.

[0651] ​ In the example shown, the case of notifying one SRS transmission subframe structure or the identifier representing this structure is utilized as the information for starting the SRS transmission. In step ST6206, the UE uses the multiple subframe structures capable of SRS transmission for each UE notified in step ST6203 and the identifier notified in step ST6205 to select the subframe structure for actually transmitting SRS. In step ST6207, the UE starts the SRS transmission according to the selected subframe structure.

[0652] By using L1 / L2 control signaling in the notification in step ST6205, the UE can start the SRS transmission dynamically and with low latency.

[0653] In step ST6208, the cell determines whether to stop the SRS transmission performed by the UE. If it is determined not to stop, the cell continues to receive SRS. If it is determined to stop the SRS transmission, in step ST6209, the cell notifies the UE of the information for stopping SRS.

[0654] In step ST6210, the UE stops the SRS transmission according to the information for stopping the SRS transmission notified in step ST6209. By using L1 / L2 control signaling in the notification in step ST6209, the UE can stop the SRS transmission dynamically and with low latency.

[0655] ​In the example shown, the case of notifying an SRS transmission subframe structure or an identifier representing the structure is used as information for starting the SRS transmission, but it is also possible to notify the information for starting the SRS transmission. The information for starting the SRS transmission can be notified together with an SRS transmission subframe structure or an identifier representing the structure. The UE uses the notified multiple subframe structures capable of performing SRS transmission for each UE and the notified identifier to select the subframe structure for actually transmitting the SRS, and starts the SRS transmission according to the notified information for starting the SRS transmission.

[0656] Thus, by notifying the UE of multiple SRS-transmittable subframe structures in advance and selecting one subframe structure therefrom, the amount of information notified using the L1 / L2 control signal can be reduced. The usage efficiency of radio resources can be improved.

[0657] In addition, when only one SRS-transmittable subframe structure is notified instead of multiple SRS-transmittable subframe structures in step ST6203, in step ST6204, the cell determines whether to cause the UE to start SRS transmission, and in step ST6205, it is only necessary to notify the UE of the information for starting the SRS transmission. The UE starts the SRS transmission according to the notified information for starting the SRS transmission.

[0658] ​ and ​ is a diagram showing an example of an SRS transmission procedure in the case of configuring multiple subframes capable of performing SRS transmission and changing the SRS subframe structure. ​ and ​ are connected at the position of the boundary line BL15. In step ST6301, the cell determines the initial SRS transmission subframe structure. In step ST6302, the cell notifies the UE of multiple subframe structures capable of performing SRS transmission for each UE. The cell notifies the UE of the identifier of the initial SRS transmission subframe structure together with the multiple SRS subframe structures. It is sufficient to use UE-specific RRC signaling for this notification.

[0659] In step ST6303, the UE uses the multiple subframe structures capable of performing SRS transmission for each UE notified in step ST6302 and the initial SRS transmission subframe structure identifier to select the subframe structure for actually transmitting the SRS. In step ST6304, the UE starts the SRS transmission according to the selected subframe structure.

[0660] In step ST6305, the cell decides on a change in the SRS transmission subframe structure. In step ST6306, the cell selects one SRS-transmittable subframe structure from among the multiple SRS-transmittable subframe structures determined in step ST6202. In step ST6307, the cell notifies the UE of the selected SRS transmission subframe structure. At this time, the cell can use an identifier to notify the UE of the selected SRS transmission subframe structure.

[0661] In step ST6308, the UE uses the multiple subframe structures capable of per-UE SRS transmission notified in step ST6302 and the identifier notified in step ST6307 to select the subframe structure for actually transmitting the SRS. In step ST6309, the UE starts transmitting the SRS according to the selected subframe structure.

[0662] By using L1 / L2 control signaling in the notification in step ST6307, the UE can be made to start SRS transmission dynamically and with low latency.

[0663] In step ST6310, the cell determines whether to stop the SRS transmission performed by the UE. If it is determined not to stop, the cell continues to receive the SRS. In step ST6312, the cell determines whether to change the SRS transmission subframe structure. If it is determined to change, the process returns to step ST6306. If it is determined not to change, the cell continues to receive the SRS in step ST6309.

[0664] If the cell determines to stop SRS transmission in step ST6310, in step ST6209, the UE is notified of the information for stopping SRS transmission.

[0665] In step ST6210, the UE stops SRS transmission according to the information for stopping SRS transmission notified in step ST6209. By using L1 / L2 control signaling in the notification in step ST6209, the UE can be made to stop SRS transmission dynamically and with low latency.

[0666] Thus, by notifying the UE of multiple SRS-transmittable subframe structures in advance and selecting one subframe structure from among them, when changing the subframe for actually transmitting the SRS, it is only necessary to notify the UE of the identifier, which can reduce the amount of information notified using the L1 / L2 control signal. The usage efficiency of radio resources can be improved.

[0667] Multiple subframe structures for actually transmitting the SRS of each UE can be set for one UE. Thereby, the transmission modes of the SRS can be increased. In addition, for each of the multiple subframe structures capable of SRS transmission for each UE, it is only necessary to set the subframe structure for actually transmitting the SRS of each UE. Thereby, the transmission modes of the SRS can be further increased. Therefore, it is possible to perform SRS transmission more suitable for the moving speed of the UE, the radio wave propagation environment, etc.

[0668] Information on the SRS transmission subframe structure or information indicating the structure can be included in the information for stopping SRS transmission. This information can be, for example, the above identifier. Among the multiple subframe structures for actually transmitting the SRS of each UE, the transmission mode of the SRS to be stopped can be uniquely determined. Therefore, the setting of SRS transmission can be made flexible. The same applies to the information for changing SRS transmission.

[0669] By applying the above method, multiple SRS transmissions can be set at one time. For example, multiple subframe structures are set for the UE as the subframe structures capable of SRS transmission for each cell or each UE, and multiple subframe structures for actually transmitting the SRS are set therefrom. Alternatively, only multiple subframe structures can be set for the UE as the subframe structures for actually transmitting the SRS of each UE. The UE transmits the SRS according to the multiple subframe structures for actually transmitting the SRS set. As described above, the subframe structure can be constituted by symbol units. Multiple symbols within one subframe can be used for SRS transmission.

[0670] By changing the number of SRS transmissions set at one time, multiple SRS transmission modes can be set. The cell can dynamically change the number of SRS transmissions set at one time. The cell can also set the number of SRS transmissions set at one time together with the change of the SRS transmission period. It is only necessary to set the number of SRS transmissions set at one time in the same way as the change of the SRS transmission period.

[0671] Multiple SRS transmission modes can be prepared in advance, and one SRS transmission mode can be selected from these modes. The multiple SRS transmission modes can be prepared, for example, by changing the number of SRS transmissions included in the subframe structure, the SRS transmission period of each SRS transmission setting, etc. The multiple SRS transmission modes can be determined statically by a standard, etc., or can be notified to the UE by the cell quasi-statically using RRC signaling, etc. An identifier can be set for each SRS transmission mode. The cell notifies the UE of the identifier of this mode. The UE starts SRS transmission according to the received mode identifier and the SRS setting of this mode.

[0672] Accordingly, a diverse SRS transmission mode including multiple SRS transmission modes can be set, and the UE can transmit in diverse SRS transmission modes. Settings suitable for diverse communication services of the UE and SRS transmission in various situations can be made.

[0673] In LTE, not only can the setting of periodic SRS be performed, but also the setting of aperiodic SRS can be performed. The setting method of periodic SRS in the method disclosed in this embodiment can be combined with the setting methods of periodic SRS and aperiodic SRS in LTE. When it is necessary to change the period of SRS with lower latency, the periodic SRS disclosed in this embodiment can be set, or alternatively, the SRS transmission period of the periodic SRS disclosed in this embodiment can be changed. Which SRS to set or change can be appropriately determined according to the required delay amount, etc.

[0674] The subframe structure capable of performing SRS transmission for each cell can be notified between adjacent eNBs. In addition, the subframe structure capable of performing SRS transmission for each UE can also be notified between adjacent eNBs. In addition, the subframe structure actually transmitting the SRS of each UE can also be notified between adjacent eNBs. The notification between adjacent eNBs can be performed directly or via a CN (core network) node. Accordingly, the UE can perform coordinated SRS transmission between adjacent eNBs.

[0675] For example, in handover (HO) between eNBs, the source eNB (S-eNB) of the HO source can notify the target eNB (T-eNB) of the HO target of the subframe structure capable of performing SRS transmission for each cell of the HO source cell, the subframe structure capable of performing SRS transmission for each UE of the UE undergoing HO, and the subframe structure actually transmitting the SRS of each UE. The notification can be performed using the signaling for the HO request.

[0676] Accordingly, the T-eNB can set the subframe structure capable of performing SRS transmission for each cell of the HO source cell, the subframe structure capable of performing SRS transmission for each UE of this UE, and the subframe structure actually transmitting the SRS of each UE, taking into account the SRS subframe structure of this UE in the HO source cell.

[0677] In 3GPP, the TRP (transmission reception point) and DU (distributed unit) are explored as nodes of NR. The method disclosed in this embodiment can also be applied to the TRP and DU. The method disclosed in this embodiment can also be applied by replacing the cell with the TRP and DU.

[0678] Alternatively, for each TRP or each DU, only the subframe structure capable of actually transmitting SRS can be set. The subframe structure capable of SRS transmission for each cell and the subframe structure capable of SRS transmission for each UE can be set by the upper node of each TRP or the upper node of each DU, such as a CU (central unit: central unit). For example, even when the UE moves between TRPs or DUs, there is no need to re-set the subframe structure capable of SRS transmission for each cell and the subframe structure capable of SRS transmission for each UE. It is only necessary to set the subframe structure capable of actually transmitting SRS.

[0679] The subframe structure capable of actually transmitting SRS for each UE can be notified between the TRP or DU and each upper node. In addition, when the UE moves between TRPs or DUs, the subframe structure capable of actually transmitting SRS in the UE moving between TRPs or DUs can be notified. This notification can be performed via the upper node.

[0680] Thus, by applying the method disclosed in this embodiment to the TRP and DU, it is also possible to attempt to improve the precoding performance in the case of downlink MIMO using the TRP and DU.

[0681] Modification Example 1 of Embodiment 2.

[0682] In this modification example, other methods for solving the problems disclosed in Embodiment 2 are disclosed.

[0683] The period during which the UE actually transmits periodic SRS (hereinafter sometimes referred to as the "SRS transmission period") is set as MAC control information. It can also be set as a MAC CE (Control Element: control element). The cell notifies the UE using MAC signaling. For the set information, Embodiment 1 can be applied.

[0684] In the case of notifying using MAC signaling, HARQ is applied. When the UE cannot correctly receive the MAC signaling notified to the UE by the cell, the UE sends a Nack to the cell, and the cell re-transmits to the UE through retransmission control.

[0685] Therefore, different from the case of notifying using L1 / L2 control signaling, it is necessary to set it considering retransmission.

[0686] When it is confirmed that the MAC signaling including the SRS transmission period sent to the UE is correctly received in the UE, the cell changes the reception of the periodic SRS in the set SRS transmission period. When the MAC signaling including the SRS transmission period sent from the cell is correctly received, the UE changes the transmission of the periodic SRS in the set SRS transmission period.

[0687] For the MAC signaling including the SRS transmission period sent to the UE, when it is confirmed that an Ack is received from the UE, the cell changes the reception of the periodic SRS in the set SRS transmission period. When the MAC signaling including the SRS transmission period sent from the cell is correctly received and an Ack is sent, the UE changes the transmission of the periodic SRS in the set SRS transmission period.

[0688] The same applies when starting the transmission of the periodic SRS by notifying the SRS transmission period.

[0689] When it is confirmed that the MAC signaling including the SRS transmission period sent to the UE is correctly received in the UE, the cell starts receiving the periodic SRS in the set SRS transmission period. When the MAC signaling including the SRS transmission period sent from the cell is correctly received, the UE starts transmitting the periodic SRS in the set SRS transmission period.

[0690] The same applies when the SRS transmission offset is set.

[0691] When it is confirmed that the MAC signaling including the SRS transmission period sent to the UE is correctly received in the UE, the cell counts the SRS transmission offset. When the MAC signaling including the SRS transmission period sent from the cell is correctly received, the UE counts the SRS transmission offset.

[0692] For example, as the SRS transmission offset value, in the case of the number of subframes capable of SRS transmission from after the setting of the SRS transmission period until the start of the periodic SRS transmission, the cell confirms that the MAC signaling including the SRS transmission period sent to the UE is correctly received in the UE, and then, in the subframe capable of SRS transmission after the SRS transmission offset, changes the reception of the periodic SRS in the set SRS transmission period. After correctly receiving the MAC signaling including the SRS transmission period sent from the cell, the UE changes the transmission of the periodic SRS in the set SRS transmission period in the subframe capable of SRS transmission after the SRS transmission offset.

[0693] As a result, the start timing of the transmission and reception of the periodic SRS can be made consistent between the UE and the cell. As a result, the transmission process of the periodic SRS can be executed without malfunctioning of the system. The same applies to the start and stop of the periodic SRS.

[0694] Also in the case where MAC signaling is used to notify information for starting SRS transmission or information for stopping SRS transmission, the start or stop timing of the transmission and reception of the periodic SRS can be made consistent between the UE and the cell. As a result, the transmission process of the periodic SRS can be executed without malfunctioning of the system.

[0695] In addition, similarly to Embodiment 2, as the above offset information, the remainder obtained by dividing the subframe number for transmitting SRS by the SRS transmission period can be used. As a result, the cell and the UE can use a unique offset regardless of whether retransmission of the above MAC signaling for the UE occurs.

[0696] As disclosed in this embodiment, in the case of changing the SRS transmission period, the SRS transmission period is set as MAC control information and notified using MAC signaling. As a result, compared with the change using the existing RRC signaling, notification can be performed in a shorter period. The time from when the cell determines to change at least one of the SRS transmission period and the SRS transmission offset value until the UE transmits the periodic SRS with the changed setting can be made shorter than the existing case.

[0697] Therefore, the delay time in the period setting of the SRS can be reduced, and thus the UE can transmit the SRS when necessary. As a result, the precoding performance for downlink MIMO can be improved.

[0698] In addition, different from the case of using L1 / L2 control signaling disclosed in Embodiment 2, retransmission control is applied in the case of using MAC signaling. As a result, the cell can receive the SRS transmitted from the UE with a lower error rate. Therefore, the precoding performance can be improved.

[0699] Modification Example 2 of Embodiment 2.

[0700] In Embodiment 2 and Modification Example 1 of Embodiment 2, the SRS transmission period is set according to the judgment of the eNB. However, in the case where the eNB uses reversibility and uses SRS to measure the reception state of the UE, if the set SRS period is long, the rapid change in the reception state of the UE cannot be grasped in the eNB. In such a case, the eNB cannot receive the SRS at a period suitable for the change in the moving speed of the UE in a short time and the rapid change in the radio wave transmission environment. Therefore, there is a problem that the precoding performance deteriorates.

[0701] In this modification example, a method for solving such a problem is disclosed.

[0702] The UE requests a change in the SRS transmission period for the cell. Information for setting the change in the SRS transmission period is set and notified by the UE to the cell. As the information for requesting a change in the SRS transmission period, information indicating whether to make the request can be set. It can be 1-bit information.

[0703] A method for notifying information for requesting a change in the SRS transmission period (hereinafter sometimes referred to as "SRS period change request information") is disclosed. The SRS period change request information is set as uplink L1 / L2 control information. The UE notifies the SRS period change request information to the cell using L1 / L2 control signaling. The UE can notify the SRS period change request information as uplink control information (UCI) transmitted using uplink L1 / L2 control signaling. The SRS period change request information can be mapped to an uplink physical control channel for notification.

[0704] The UE can include the SRS period change request information in the UCI and map it to a physical dedicated control channel to notify the cell. Here, the physical dedicated control channel corresponds to the PUCCH in LTE. The structure of the physical dedicated control channel used for the notification of the SRS period change request information and the mapping method to physical resources are preset by the cell and notified to the UE. This notification can use RRC dedicated signaling. Or, it can be determined statically through standards or the like. As the above method, the same method as the scheduling request (SR) in LTE can also be applied (refer to 3GPP TS 36.211 V13.2.0 (hereinafter referred to as "Reference 4"), and 3GPP TS 36.213 V13.2.0 (hereinafter referred to as "Reference 5").

[0705] In LTE, the minimum period of the SR is 5 ms, but a shorter period can also be set. For example, 2 ms, 1 ms, etc. can be set as the period of the SRS period change request. Thereby, the time from when the UE determines a change request for the SRS transmission period to when the change request for the SRS transmission period is transmitted can be shortened.

[0706] Other notification methods for the SRS period change request information are disclosed. Use an uplink RS. Use an RS that is transmitted in a manner matching the case where the UE transmits in the uplink using the PUCCH or PUSCH. As specific examples of methods for recognizing that this RS is different from the normal RS and is for the SRS period change request, the following three (1) to (3) are disclosed.

[0707] (1) Set a specific sequence number for the SRS period change request.

[0708] (2) Set a specific CS (cyclic shift) for the SRS period change request.

[0709] (3) Modulate the bits of the RS according to the presence or absence of an SRS period change request.

[0710] In the method of setting a specific sequence number for the SRS period change request in (1) above, it is sufficient to set a sequence number different from the sequence number used for the normal RS. Thus, the cell can identify whether it is an SRS period change request based on the sequence number of the RS transmitted by the UE.

[0711] In the method of setting a specific CS for the SRS period change request in (2) above, it is sufficient to set a CS different from the CS used for the normal RS. Thus, the cell can identify whether it is an SRS period change request based on the CS of the RS transmitted by the UE. In the case of CS, orthogonality is maintained between different CSs, so the cell can identify whether it is a normal RS or an SRS period change request with a lower error rate.

[0712] In the method of modulating the bits of the RS according to the presence or absence of an SRS period change request in (3) above, for example, BPSK (Binary Phase Shift Keying) modulation can be performed. In the case of an SRS period change request, multiply the bits of the normal RS by "1", and in the case of no SRS period change request, multiply the bits of the normal RS by "-1". Thus, the cell can identify whether it is an SRS period change request by receiving the modulated RS.

[0713] Thus, by using the method of notifying the SRS period change request using the uplink RS, no new radio resources on the frequency-time axis are required. Therefore, the SRS period change request can be made without reducing the utilization efficiency of radio resources.

[0714] As the uplink RS, SRS can be used. In the case of using SRS, the same method as the above method can also be applied.

[0715] Other notification methods for the SRS period change request information are disclosed. Set the SRS period change request information as MAC control information. It can also be set as MAC CE (Control Element). The UE notifies the cell using MAC signaling. Since HARQ is applied in the case of notification using MAC signaling, the cell can receive the SRS period change request information sent from the UE with a lower error rate.

[0716] Another notification method for disclosing SRS period change request information. Set the SRS period change request information as RRC information. The UE notifies the cell using RRS signaling. Since HARQ is also applied when using RRC signaling for notification, the cell can receive the SRS period change request information sent from the UE with a lower error rate. When using RRC signaling, it is particularly effective when the set SRS period is larger than the period taken for the notification of the RRC signaling.

[0717] A judgment index for changing the SRS transmission period by the cell can be sent together with the notification of the SRS period change request information. As the judgment index for changing the SRS transmission period by the cell, the judgment index for changing the SRS transmission period disclosed in Embodiment 2 can be applied.

[0718] The cell that has received the SRS period change request information from the UE starts the process of changing the setting of the SRS transmission period for this UE. At this time, the cell can judge whether to change the SRS transmission period for this UE. It is possible to change the setting of the SRS transmission period when a change is needed, and not to change the setting of the SRS transmission period when no change is needed.

[0719] In the above judgment of whether to change the SRS transmission period, the cell can notify the UE of the intention not to make a change. The cell can also notify the UE of the reason for not making a change. Thus, for the SRS period change request from this UE, the cell can notify the UE of the situation where other UEs have already sent SRS at the same timing. In addition, this UE can request a period different from the previous SRS period change request from the cell. Therefore, even when other UEs send SRS, the cell can maintain the precoding performance in the communication with this UE.

[0720] The UE can notify the SRS transmission offset change request together with the SRS period change request. Or, the UE can notify the SRS transmission offset change request separately from the SRS period change request. Just use the same method as the SRS period change request to notify the SRS transmission offset change request.

[0721] The cell that has received the SRS transmission offset change request information from the UE starts the process of changing the setting of the SRS transmission offset for this UE. At this time, the cell can judge whether to change the SRS transmission offset for this UE. It is possible to change the setting of the SRS transmission offset when a change is needed, and not to change the setting of the SRS transmission offset when no change is needed.

[0722] In the determination of whether to change the SRS transmission offset as described above, the cell can notify the UE that it will not make a change. The cell can also notify the UE of the reason for not making the change. Thus, for an SRS offset change request from this UE, the cell can notify the UE that another UE has already transmitted SRS at the same timing. In addition, this UE can request a period different from the previous SRS transmission offset change request from the cell. Therefore, even when another UE transmits SRS, the cell can maintain the precoding performance in the communication with this UE.

[0723] ​ It is a diagram showing an example of the process of a UE transmitting SRS period change request information in Modification Example 2 of Embodiment 2. ​ The process shown includes the same steps as ​ the process shown. Therefore, the same step numbers are assigned to the same steps, and the common description is omitted.

[0724] In step ST3401, the UE transmits SRS to the cell at the set SRS transmission period.

[0725] In step ST3402, the UE determines whether to transmit an SRS period change request. In this determination, the determination criteria for changing the SRS transmission period disclosed in Embodiment 2 can be used. Among them, regarding the multiplexing number of the UE, since the UE cannot identify it, it is excluded.

[0726] If it is determined in step ST3402 that there is no need to transmit an SRS period change request, SRS is transmitted at the set SRS period.

[0727] If it is determined in step ST3402 that an SRS period change request needs to be transmitted, the process proceeds to step ST3403.

[0728] In step ST3403, the UE sends an SRS period change request to the cell. The UE sets the SRS period change request information of the uplink L1 / L2 control information to "requested" and notifies the cell using L1 / L2 control signaling.

[0729] In step ST3403, the cell that has received the SRS period change request from the UE determines in step ST3404 whether to change at least one of the SRS transmission period and the SRS transmission offset value for this UE. In this determination, the determination criteria for changing the SRS transmission period disclosed in Embodiment 2 can be used.

[0730] When it is determined in step ST3404 that at least one of the SRS transmission period and the SRS transmission offset value needs to be changed, the process returns to step ST3305, and at least one of the SRS transmission period and the SRS transmission offset value for each UE is set. In the above setting, use the judgment index for changing the SRS transmission period to derive the degree of change required, and set at least one of the SRS transmission period and the SRS transmission offset value.

[0731] When it is determined in step ST3404 that there is no need to change the SRS transmission period and the SRS transmission offset value, the cell continues to receive periodic SRS with the same setting. Since there is no notification of the change or stop of the periodic SRS, the UE continues to transmit periodic SRS with the same setting.

[0732] When it is determined in step ST3404 that at least one of the SRS transmission period and the SRS transmission offset value is not changed for this UE, the cell continues to receive SRS with the SRS period set for the UE.

[0733] By using the method disclosed in this modification example, the UE can notify the cell of the change request information of the SRS transmission period. Thus, even if the set SRS is a long period, the UE can notify the cell of the change request information of the SRS transmission period when it detects a change in its own moving speed within a short time and a rapid change in the radio wave transmission environment. Therefore, the cell can set an SRS transmission period suitable for the change in the moving speed within a short time and the rapid change in the radio wave transmission environment for the UE. Thus, the cell can receive SRS from the UE at an appropriate period. Thereby, the degradation of the precoding performance for downlink MIMO can be reduced.

[0734] The UE can request the cell to notify the end of the change of the SRS transmission period. Set the change end request information of the SRS transmission period and notify it to the cell by the UE. This information can be set as a 1-bit information. Information indicating whether it is the change request information or the change end request information of the SRS transmission period can be set. This information can be set as a 1-bit information.

[0735] The cell that receives the change end request information of the SRS transmission period from the UE ends the setting of changing the SRS transmission period for this UE and returns to the original setting. The cell notifies the UE of the originally set SRS transmission period. Information indicating the return to the original setting can be set. When returning the setting of the SRS transmission period that has been changed for the UE to the original setting, it is sufficient for the cell to notify this information to the UE. There is no need to notify the originally set SRS transmission period, and it is possible to reduce the amount of information required to achieve communication.

[0736] The UE can appropriately apply the method disclosed in the change request information regarding the above SRS transmission period to the method of notifying the cell. Thus, the UE can notify the cell of the situation where it hopes to end the change of the SRS transmission period. For example, when the UE's moving speed becomes faster, it notifies the cell of the change request of the SRS transmission period, and correspondingly, the cell makes a change setting of the SRS transmission period. When the moving speed returns to the original state later, a request to end the change of the SRS transmission period is generated in the UE. In this case, the UE sends a request to end the change of the SRS transmission period to the cell. Thus, the SRS transmission period can be set according to the situation of the UE, the communication quality between the UE and the cell, etc.

[0737] The UE can notify the cell of a request to shorten the SRS transmission period or a request to extend the SRS transmission period. Set the information of the request to shorten the SRS transmission period or the request to extend the SRS transmission period, and the UE notifies it to the cell. Information indicating whether it is a request to shorten the SRS transmission period or a request to extend the SRS transmission period can be set. This information can be set as 1-bit information.

[0738] The cell that receives the request to shorten the SRS transmission period from the UE makes a shortening setting of the SRS transmission period of this UE. The cell notifies the set SRS transmission period to the UE. The cell that receives the information of the request to extend the SRS transmission period from the UE makes an extension setting of the SRS transmission period of this UE. The cell notifies the set SRS transmission period to the UE.

[0739] The UE can appropriately apply the method disclosed in the change request information regarding the above SRS transmission period to the method of notifying the cell. Thus, the UE can notify the cell whether it wants to shorten or extend the SRS transmission period. For example, a request to shorten the SRS transmission period is made when the UE's moving speed becomes faster, and a request to extend the SRS transmission period is made when the battery level of the UE is low. Thus, the SRS transmission period can be set according to the situation of the UE, the communication quality between the UE and the cell, etc.

[0740] The UE can notify the cell of a request to stop SRS transmission or a request to start SRS transmission. Set the information of the request to stop SRS transmission or the request to start SRS transmission, and the UE notifies it to the cell. Information indicating whether it is a request to stop SRS transmission or a request to start SRS transmission can be set. This information can be set as 1-bit information.

[0741] A cell that receives a stop request message for SRS transmission from a UE sets the SRS transmission of the UE to stop. The cell notifies the UE of the information for stopping SRS transmission. The UE stops SRS transmission according to the information for stopping SRS transmission. A cell that receives a start request message for SRS transmission from a UE sets the SRS transmission of the UE to start. The cell notifies the UE of the information for starting SRS transmission. The UE starts SRS transmission according to the information for starting SRS transmission.

[0742] For the UE's notification method to the cell, etc., the method disclosed for the change request message regarding the above SRS transmission period can be appropriately applied. Thus, the UE can notify the cell of the desire to stop or start SRS transmission. For example, the following situation occurs: SRS transmission can be temporarily stopped when the UE is stationary, and the communication quality is stable and good. In this case, in order to request the temporary stop of SRS transmission, the UE can notify the cell of the SRS transmission stop request. In addition, for example, when the UE starts to move and the communication quality condition becomes unstable, it is necessary to restart SRS transmission. In this case, in order to request the restart of SRS transmission, the UE can notify the cell of the SRS transmission start request. Thus, the stop and restart of SRS transmission can be set according to the UE's condition, the communication quality between the UE and the cell, etc.

[0743] Embodiment 2 Variant 3.

[0744] When the UE cannot receive the information for stopping SRS transmission from the cell, there is a problem that SRS is continuously transmitted and cannot be stopped.

[0745] For example, when the cell transmits the information for stopping SRS transmission and the information for starting SRS transmission at independent timings, if the UE cannot receive the information for stopping SRS transmission, it cannot stop the SRS transmission started according to the information for starting SRS transmission. Thus, the problem of continuously transmitting SRS occurs.

[0746] As a method to solve this problem, it is sufficient to set a maximum transmission time. The cell notifies the UE of the maximum transmission time. After SRS transmission starts according to the information for starting SRS transmission, if the maximum transmission time has elapsed, the UE stops SRS transmission. Thus, the problem that the UE continuously transmits SRS and cannot stop it can be solved.

[0747] The maximum transmission time can be managed by the UE's timer. The UE starts the timer at the timing when starting according to the information for starting SRS transmission. As the information for starting SRS transmission, there is SRS transmission start information and offset information. In the case where there is offset information, the offset information can be taken into account when starting the timer.

[0748] Alternatively, in the case where the periodic SRS transmission is started by notifying the UE of the SRS transmission period, the UE starts a timer at the timing of starting the SRS transmission. Thus, it suffices to start the timer at the timing when the UE starts the SRS transmission.

[0749] If the maximum transmission time has elapsed since the start of the timer, the UE stops the SRS transmission regardless of the reception of the information for stopping the SRS transmission. The UE stops the SRS transmission and resets the timer. Thus, the SRS transmission can be stopped after the maximum transmission time has elapsed since the start of the first SRS transmission.

[0750] In this case, if the UE receives the information for stopping the SRS transmission from the start of the first SRS transmission until the maximum transmission time has elapsed, problems may occur. Even if the UE stops the SRS transmission in accordance with the reception of the information for stopping the SRS transmission, the timer is not reset. When the UE receives the information for starting the next SRS transmission or the SRS transmission period information before the elapse of the maximum transmission time, the UE starts the SRS transmission in accordance with this information.

[0751] In this case, if the maximum transmission time elapses immediately after the UE starts the SRS transmission, the UE stops the SRS transmission. As a method for solving this problem, the timer can be reset when the UE receives the information for stopping the SRS transmission from the start of the first SRS transmission until the maximum transmission time has elapsed. Alternatively, the timer can also be reset when the SRS transmission has been stopped.

[0752] Thus, the problem that the SRS transmission stops immediately from the start of the second and subsequent SRS transmissions can be avoided.

[0753] The maximum transmission time can be determined statically in advance using a standard or the like. The information on the maximum transmission time can be notified to the UE by the cell quasi-statically or dynamically. The information on the maximum transmission time can be notified using RRC signaling. Alternatively, the information on the maximum transmission time can be notified using L1 / L2 control signals. Alternatively, the information on the maximum transmission time can also be notified using MAC signaling.

[0754] The maximum transmission time can be set for each cell. The complexity of control can be avoided. As another method, the maximum transmission time can be set for each beam. The coverage ranges and the like provided for each beam are different. In this case, by setting different values for each beam, the beam structure can be made flexible. As another method, the maximum transmission time can be set for each UE. Since the value for each UE can be set, the maximum transmission time can be set according to the status of the UE, for example, according to the capabilities of the UE, the services with which the UE is communicating, and the like.

[0755] In the above method, the maximum transmission time is set to a time. In addition, the case of using a timer to manage the maximum transmission time is disclosed. As another method, the maximum number of transmissions of the SRS can be set. The cell notifies the UE of the maximum number of transmissions. When starting the SRS transmission, the UE stops the SRS transmission after transmitting the SRS the maximum number of times. In addition, when the SRS transmission is stopped, the count is reset.

[0756] Thus, the same effect as setting the maximum transmission time can be obtained. In addition, for example, like the specific example of the determination index for changing the SRS transmission period disclosed in Embodiment 2, the SRS transmission period can be set according to the condition of the UE. In this case, if the maximum transmission time is used, different maximum transmission times must be set for each UE, and the control becomes complicated. For example, if the maximum number of transmissions is used, even when the SRS transmission periods are different, the maximum transmission time corresponding to the SRS transmission period can be set.

[0757] Embodiment 3.

[0758] In LTE, the PUCCH to which uplink control signals such as Ack / Nack, CQI / CSI, and SR are mapped is mapped to all symbols within one subframe. In addition, the SRS is transmitted in the last symbol within one subframe (refer to Reference 4).

[0759] When the timing of the transmission of Ack / Nack and the SRS conflicts in a certain UE, the last symbol of the PUCCH to which Ack / Nack is mapped and that conflicts with the SRS is punctured for transmission. Only the last symbol among the 14 symbols (including RS) within one subframe of this PUCCH is punctured, and the other symbols are transmitted.

[0760] ​ is a diagram for explaining the case where the transmission timing of Ack / Nack and the SRS in LTE conflicts. In ​ , the horizontal axis represents time t, and the vertical axis represents frequency f. ​ In the uplink subframe of, one subframe consists of 14 symbols. The PUCCH is mapped to both ends of the system frequency band in units of RB (resource block), and the PUSCH is mapped therebetween. ​ The description of RS is omitted in, but the RS is mapped to predetermined symbols within the area to which the PUCCH is mapped and the area to which the PUSCH is mapped.

[0761] The SRS is set to the last symbol of one subframe. In the subframe where the SRS is set, the PUSCH is not mapped to the last symbol. For a certain UE, when the transmission of the SRS and the transmission of the PUCCH are set in the same subframe, the UE punctures the last symbol of the PUCCH of this subframe for transmission. In other words, the UE does not transmit the last symbol of the PUCCH of this subframe. The UE transmits the SRS with predetermined resources in this subframe.

[0762] As a signal applying this method, there is the uplink Ack / Nack for downlink data. The Ack / Nack consists of 1 bit or 2 bits, is spread and mapped to the PUCCH. Only the last symbol among the 14 symbols (including RS) in one subframe of the PUCCH is punctured, and the other symbols are transmitted. Therefore, the cell can identify the Ack / Nack by receiving the PUCCH on the other transmitted symbols.

[0763] Thus, even if a conflict occurs between the transmission of the Ack / Nack and the SRS in the same subframe, the UE can transmit both the Ack / Nack and the SRS, and the eNB can receive both the Ack / Nack and the SRS from the UE in the same subframe.

[0764] On the other hand, as the subframe structure of NR, it is proposed that the uplink control signals such as Ack / Nack are not mapped to all the symbols in one subframe, but are mapped to the symbols at the rear of the subframe. In addition, regarding the SRS, it is also proposed to transmit in one symbol at the rear in one subframe. For example, it is proposed that in a self - contained subframe, the uplink control signals such as Ack / Nack and the SRS are transmitted in the last symbol in the subframe (refer to Non - Patent Document 9 and 3GPP R1 - 167203 (hereinafter referred to as "Reference Document 6")).

[0765] When a conflict occurs in the timing of the transmission of the uplink control signals such as Ack / Nack and the transmission of the SRS in a certain UE, if the last symbol to which the uplink control signals such as Ack / Nack are mapped is punctured and not transmitted in the same way as in the existing LTE method, there will be a problem of not transmitting the uplink control signals such as Ack / Nack.

[0766] The uplink control signals such as Ack / Nack are transmitted in the last symbol in one subframe, and not in other symbols. Therefore, if the last symbol that conflicts with the SRS is punctured, the uplink control signals such as Ack / Nack that are only mapped to this symbol are not transmitted.

[0767] In this embodiment, a method for solving the above problems is disclosed.

[0768] Frequency division multiplexing is performed on the uplink control signal and SRS on the same symbol. Uplink control signals such as Ack / Nack are transmitted in the symbol in which SRS is transmitted. It is possible to transmit an uplink control signal and SRS of a UE different from the UE transmitting the uplink control signal in the same symbol. It is also possible to transmit an uplink control signal and SRS of the same UE as the UE transmitting the uplink control signal in the same symbol.

[0769] Since frequency division multiplexing is performed on the uplink control signal and SRS on the same symbol, flexible scheduling of the uplink control signal can be performed in the frequency axis direction. The uplink control signal can be allocated to a frequency resource different from other information mapped within the same subframe for this UE. As other information mapped within the same subframe for this UE, for example, there are downlink data, downlink control information, uplink data, etc. As an allocation method, there are a method of allocating consecutive subcarriers within a certain frequency range and a method of allocating scattered subcarriers within a certain frequency range.

[0770] It can be allocated to a frequency resource for which no other UE is scheduled. Since there is no need to multiplex with other UEs, the reception error rate in the cell can be reduced. In addition, the complexity caused by the control for multiplexing can be reduced.

[0771] In addition, it can also be allocated to a frequency resource for which other UEs are scheduled. In this case, multiplexing is performed with other UEs. As a method of multiplexing using the same frequency resource among multiple UEs, code division multiplexing can be used. Orthogonal codes are used for multiplexing among UEs. Or, scrambling codes are used for multiplexing among UEs. Thereby, the uplink control signal can be multiplexed with the uplink control signal or uplink information of other UEs. Therefore, flexible scheduling of the uplink control signal can be performed in the frequency axis direction.

[0772] The cell includes scheduling information including allocation information and multiplexing method for the frequency resource in the L1 / L2 control information and transmits it to the UE using the L1 / L2 control signaling. The scheduling information can be notified in the same subframe or in different subframes. In the case of different subframes, it is sufficient to notify information indicating which subframe is scheduled together.

[0773] Thereby, the uplink control signal can be allocated to a frequency resource different from other information mapped within the same subframe. In this specification, regarding the RS transmitted along with the uplink control signal, sometimes the description is omitted, but regarding the RS transmitted along with the uplink control signal, it is transmitted along with the uplink control signal in the same manner as the uplink control signal.

[0774] In the case of frequency-division multiplexing of an uplink control signal and SRS on the same symbol, the cell may allocate frequency resources that are not set for the SRS actually transmitted in the symbol as the frequency resources for the uplink control signal. The cell notifies the UE of the scheduling information of the frequency resources for the uplink control signal using the above method.

[0775] ​ is a diagram showing an example of the case where the uplink control signal and SRS in Embodiment 3 are frequency-division multiplexed and transmitted on the same symbol. In ​ , the horizontal axis represents time t, and the vertical axis represents frequency f. One subframe consists of 14 symbols. The first three symbols of one subframe are mapped with downlink L1 / L2 control information. The last symbol of one subframe is set as the symbol capable of transmitting SRS. ​ The solid slanted shading extending diagonally downward in

[0776] shows the SRS actually transmitted in the symbol. For UE#a, a self-contained subframe is formed in the frequency range a. For UE#a, the DL data is mapped to the 4th to 10th symbols of one subframe, and a gap is formed in the 11th to 13th symbols of one subframe. ​ shows the case of Ack / Nack as the uplink control signal.

[0777] In an existing self-contained subframe, an Ack / Nack signal for downlink data is transmitted in the last symbol of one subframe. However, since the last symbol of this subframe is set as the symbol capable of transmitting SRS, there is sometimes a conflict with the transmission of SRS. For example, in the case where the subframe actually transmitting the SRS of other UEs is set as this subframe, the SRS of other UEs is transmitted in the last symbol of this subframe. Or, in the case where the subframe actually transmitting the SRS of this UE is set as this subframe, the SRS of this UE is transmitted in the last symbol of this subframe.

[0778] In this case, without any effort, the transmission of Ack / Nack of this UE conflicts with the transmission of SRS of other UEs or this UE, and the cell cannot correctly receive the above transmission from the UE.

[0779] Therefore, in this embodiment, as ​ shows, the Ack / Nack signal for downlink data and SRS are frequency-division multiplexed and transmitted in the last symbol of one subframe. The cell allocates frequency resources different from the frequency resources actually transmitting SRS to the Ack / Nack signal for downlink data. The frequency resources different from the frequency resources actually transmitting SRS may be frequency resources different from the frequency resources mapped with the DL data of this UE.​ In the example shown, the frequency resources allocated to frequency range b.

[0780] The scheduling information of Ack / Nack is included in the L1 / L2 control information for UE#a and is sent using L1 / L2 control signaling. The UE receives the L1 / L2 control signaling and the L1 / L2 control information targeted at this UE, thereby obtaining the allocation information of the frequency resources for Ack / Nack for the downlink data. Thus, the UE can send Ack / Nack for the downlink data without conflicting with the SRS.

[0781] Thus, even if the SRS actually transmitted in the subframe in which UE#a receives the DL data is set, Ack / Nack for the DL data can be sent in the same subframe as the received DL data.

[0782] ​ FIG. is a diagram showing another example of the case where the uplink control signal and the SRS in Embodiment 3 are frequency-division multiplexed and transmitted on the same symbol. In ​ , the horizontal axis represents time t and the vertical axis represents frequency f. ​ Similar to ​ , the description will mainly focus on the different parts and the common description will be omitted.

[0783] The Ack / Nack signal for the downlink data and the SRS are frequency-division multiplexed and transmitted in the last symbol of 1 subframe. The cell allocates scattered frequency resources different from the frequency resources of the actually transmitted SRS to the Ack / Nack signal for the downlink data. ​ In the example shown, the scattered frequency resources allocated to frequency range b. It is applicable to the case where the actually transmitted SRS is transmitted with scattered frequency resources. Thus, the utilization efficiency of radio resources can be improved.

[0784] ​ FIG. is a diagram showing another example of the case where the uplink control signal and the SRS in Embodiment 3 are frequency-division multiplexed and transmitted on the same symbol. In ​ , the horizontal axis represents time t and the vertical axis represents frequency f. ​ Similar to ​ , the description will mainly focus on the different parts and the common description will be omitted.

[0785] In the last symbol of one subframe, the Ack / Nack signal for downlink data is frequency-division multiplexed with the SRS and transmitted. The cell allocates dispersed frequency resources different from the frequency resources of the actually transmitted SRS to the Ack / Nack signal for downlink data. The frequency resources for transmitting the Ack / Nack are set to be a part of the frequency resources mapped with the DL data of this UE. ​ In the example shown, the dispersed frequency resources are allocated to the frequency range a. It is applicable to the case where the actually transmitted SRS is transmitted with the dispersed frequency resources. Thereby, the usage efficiency of radio resources can be improved.

[0786] In this case, there will be a situation where the frequency resources for transmitting the Ack / Nack do not meet the pre-determined frequency resources. ​ In the example shown, although the pre-determined frequency resources are the frequency resources mapped with the DL data of this UE, the frequency resources for transmitting the Ack / Nack are only half of it. In this case, it is only necessary to increase the transmission power of the frequency resources for transmitting the Ack / Nack. By increasing the transmission power, the received power of the cell will increase. Therefore, even if the frequency resources for transmitting the Ack / Nack do not meet the pre-determined frequency resources, the cell can receive the Ack / Nack signal from the UE with a lower error rate.

[0787] The information indicating the increase in the transmission power of the frequency resources is included in the L1 / L2 control information as scheduling information and is sent to the UE using the L1 / L2 control signaling. It can be included in the scheduling information together with the allocation information and multiplexing method for the frequency resources. The scheduling information can be notified in the same subframe or in different subframes. In the case of different subframes, it is only necessary to notify the information indicating which subframe is scheduled together.

[0788] As another method, the information indicating the method for increasing the transmission power of the frequency resources can be included in the broadcast information and broadcast. The method for increasing the transmission power of the frequency resources can be determined for each cell and broadcast. Or, the method for increasing the transmission power of the frequency resources can be determined for each cell and separately notified to the UE using the RRC dedicated signaling. Or, the method for increasing the transmission power of the frequency resources can be determined for each UE and notified to each UE using the RRC dedicated signaling.

[0789] As another method, the method for increasing the transmission power of the frequency resources can also be statically determined in advance through standards, etc. In addition, the cell can also notify the UE only of the parameters required for the method for increasing the transmission power of the frequency resources. This notification method can apply the above methods.

[0790] Accordingly, by increasing the transmission power of the radio resources for transmitting Ack / Nack, the radio resources for transmitting Ack / Nack can be reduced. Even when at least one of the cases where the number of UEs actually transmitting SRS within the same symbol increases and the number of UEs transmitting uplink control signals increases occurs, the radio resources used can be reduced, and multiple UEs can be supported.

[0791] By using the method disclosed in the present embodiment, even when an uplink control signal such as Ack / Nack and SRS conflict in the same subframe in NR, either signal can be transmitted. Therefore, the cell can receive an uplink control signal such as Ack / Nack and SRS at a predetermined timing. By being able to receive Ack / Nack at a predetermined timing, retransmission control can be performed without delay. In addition, by being able to receive SRS at a predetermined timing, the cell can perform precoding with higher accuracy.

[0792] The case where the uplink control signal and SRS conflict in the last symbol within one subframe is disclosed, but the uplink control signal and SRS can also be mapped to other symbols within one subframe. Similar to the case where a conflict occurs in the other symbol, the method disclosed in the present embodiment such as frequency division multiplexing can be applied to the symbol. In this case, the same effect as the present embodiment can also be obtained.

[0793] The case where the uplink control signal and SRS are mapped to the same symbol and conflict within one subframe is disclosed, but the uplink control signal and SRS can also be mapped to symbols with different numbers of symbols respectively. Similar to the case where a conflict occurs in some symbols in this case, the method disclosed in the present embodiment such as frequency division multiplexing can be applied to the symbols where the conflict occurs. In this case, the same effect as the present embodiment can also be obtained.

[0794] The case where the uplink control signal and SRS are mapped to the same symbol and conflict within one subframe is disclosed, but the uplink control signal and SRS can also be mapped to symbols with different numbers of symbols respectively. In the case where a conflict occurs in some symbols in this case, the frequency resources where SRS is not actually transmitted can be used to transmit all the symbols of the uplink control signal. In all the symbols of the uplink control signal including the symbol where the conflict occurs, the method disclosed in the present embodiment can be appropriately applied. In this case, the same effect as the present embodiment can also be obtained.

[0795] In the same UE, the transmission of different uplink control signals in the same subframe sometimes causes conflicts. When the transmission of different uplink control signals in one or a part of the symbols in the same subframe causes a conflict, the method disclosed in this embodiment can also be appropriately applied. For example, when the transmission of Ack / Nack and the transmission of CQI / CSI in a certain UE occur in the same symbol of the same subframe, the UE transmits without changing the radio resources for transmitting CQI / CSI, and assigns Ack / Nack to other frequency resources for transmission.

[0796] Thereby, even when Ack / Nack and CQI / CSI conflict in one or a part of the symbols in the same subframe, the UE can transmit both signals in the same subframe. In addition, the cell can receive both signals in the same subframe.

[0797] In the uplink control signal, information on which signal to transmit without changing the radio resources and which signal to assign to other frequency resources for transmission can be determined statically in advance through standards or the like. Alternatively, the cell can include the above information in the broadcast information for broadcasting. Thereby, the above information can be determined for each cell in consideration of the conditions of each cell. Alternatively, the cell can also notify the UE individually using RRC dedicated signaling. This information can be determined for each cell or for each UE. Thereby, the above information can be determined for each UE in consideration of the conditions of each UE.

[0798] When notifying the above information to each UE, MAC signaling can be used for notification. Thereby, the setting can be made earlier than with RRC signaling. Alternatively, it can be included in the L1 / L2 control information and notified using L1 / L2 control signaling. Thereby, the setting can be made even earlier than with RRC signaling. When included in the L1 / L2 control information, it can be included in the scheduling information together with the allocation information and multiplexing method for the frequency resources.

[0799] In addition, the uplink control signals are not limited to two, and can also be three or more. Just transmit one uplink control signal without changing the radio resources, and assign two uplink control signals to other frequency resources for transmission. The same method as the above method can be applied.

[0800] Thereby, even when different uplink control signals conflict in one or a part of the symbols in the same subframe, the UE can transmit both signals in the same subframe. In addition, the cell can receive both signals in the same subframe.

[0801] The cell can receive information from the UE in a pre-determined subframe, and thus can perform control on the UE in a timely manner. For example, retransmission control based on Ack / Nack can be performed without delay. In addition, for example, precoding for downlink MIMO based on CQI / CSI can be performed with high precision. Or, uplink communication can be started earlier by executing the uplink scheduling request based on SR in advance.

[0802] Modification Example 1 of Embodiment 3.

[0803] In this modification example, other methods for solving the problems disclosed in Embodiment 3 are disclosed.

[0804] In the case where an uplink control signal such as Ack / Nack and SRS conflict, time-division multiplexing is performed on the uplink control signal and SRS. In the case where an uplink control signal such as Ack / Nack and SRS conflict, the number of UL symbols in the same subframe can be increased. By increasing the number of UL symbols, the uplink control signal is mapped to the increased UL resources, and time-division multiplexing is performed on the uplink control signal and SRS.

[0805] The increased number of UL symbols is not limited to 1, and can also be multiple. The increased number of UL symbols can be set according to the number of symbols to which the uplink control signal is mapped. The increased UL symbols are set to be continuous with the existing UL symbols. If set discretely, for example, in the case where there is a DL symbol between the discretely set UL symbols, a new interval must be set, which will result in a reduction in the use efficiency of radio resources. In addition, in the case where there is an interval between the discretely set UL symbols, in order to maintain a pre-determined period, it is sometimes necessary to form a new interval between the DL symbol and the previous UL symbol, thus resulting in a reduction in the use efficiency of radio resources.

[0806] As a method of time-division multiplexing, for example, SRS is set not to be changed from the normal setting in the last symbol, and an uplink control signal such as Ack / Nack is mapped to 1 symbol before. Regarding SRS, it is not limited to the SRS of the UE that has a conflict in transmission, and the SRS of other UEs is also transmitted. Therefore, when it is set not to be changed from the normal setting, the process of changing the setting for other UEs can be omitted. Thus, the complication of control can be avoided.

[0807] The number of symbols in one subframe is determined in advance. Therefore, when increasing the uplink symbol by 1 symbol for the uplink control signal, other symbols must be reduced. Specific examples of the reduction method are disclosed as the following (1) to (3).

[0808] (1) Reduce the number of interval symbols.

[0809] (2) Reduce the number of DL symbols.

[0810] (3) A combination of the above (1) and (2).

[0811] In the case of the above (1), since the number of guard symbols is reduced, the number of data symbols can be maintained. Therefore, a decrease in the data transmission speed can be suppressed. This is effective when it is desired to suppress a decrease in the data transmission speed. In the case of the above (2), since the DL symbols are reduced, the number of guard symbols can be maintained. The number of guard symbols is determined according to the cell coverage range and the demodulation performance of the UE, etc., and thus there are cases where it is desired to be set fixed in advance. This is effective in such cases. In the case of the above (3), for example, when the number of uplink symbols is increased by 2 or more symbols, the data transmission speed and the number of guard symbols can be ensured to a certain extent.

[0812] In addition, the cell and the UE can switch between the above (1) to (3) for use. In addition, the above switching can be notified to the UE by the cell using RRC signaling, can be notified to the UE by the cell using MAC signaling, or can be notified to the UE by the cell using L1 / L2 signaling. Thus, for example, when the UE moves from the cell boundary to near the cell and the transmission time is less so that the number of guard symbols can be reduced, the data transmission speed can be maintained by switching from the above (2) to the above (1).

[0813] ​ FIG. is an example showing a case where the number of UL symbols is increased by 1 symbol and time division multiplexing is performed on Ack / Nack and SRS. In ​ the horizontal axis represents time t and the vertical axis represents frequency f. ​ Similar to ​ therefore mainly the different parts will be described and the common descriptions will be omitted.

[0814] When an uplink control signal such as Ack / Nack and SRS conflict in the last symbol of the same subframe, the second symbol with a gap from the end of the subframe is configured as a UL symbol. SRS is mapped to the last symbol without changing from the normal setting. Ack / Nack is mapped to the symbol that is configured as a UL symbol and is the second symbol from the end of the subframe.

[0815] The gap can be configured as a UL symbol only for the frequency resources of the UE that is scheduled and where Ack / Nack and SRS conflict. Or, when Ack / Nack and SRS conflict in at least one UE, the gap can be configured as a UL symbol over the entire frequency band.

[0816] Accordingly, Ack / Nack and SRS are mapped to different symbols, so the UE can send Ack / Nack and SRS in the same subframe. The cell can receive Ack / Nack and SRS from the UE in the same subframe.

[0817] ​ FIG. is a diagram showing another example in which the number of UL symbols is increased by one symbol and Ack / Nack and SRS are time-division multiplexed. In ​ the horizontal axis represents time t and the vertical axis represents frequency f. ​ and Figure 52 are similar, so mainly the different parts will be described and the common description will be omitted.

[0818] When an uplink control signal such as Ack / Nack and SRS collide in the last symbol of the same subframe, the second symbol from the end of the subframe with a gap is configured as a UL symbol, and the last symbol configured with DL data is configured as a gap. In other words, the three symbols for the gap are maintained, the last symbol for DL data is reduced, and the UL symbol is increased by one symbol in the second symbol from the end of the subframe.

[0819] Such a structure can be applied only to the frequency resources of the UE scheduled where Ack / Nack and SRS collide. Or, when Ack / Nack and SRS collide in at least one UE, this structure can be applied to all UEs in the same subframe.

[0820] Accordingly, Ack / Nack and SRS are mapped to different symbols, so the UE can send Ack / Nack and SRS in the same subframe. The cell can receive Ack / Nack and SRS from the UE in the same subframe.

[0821] Information indicating how to time-division multiplex the uplink control signal and SRS (hereinafter sometimes referred to as "information related to time-division multiplexing") can also be set. As specific examples of the information related to time-division multiplexing, the following eight (1) to (8) are disclosed.

[0822] (1) The number of increased UL symbols.

[0823] (2) The symbol number to which each uplink control signal is mapped.

[0824] (3) Information on which signal to send without changing the radio resources and which signal to allocate to the increased UL resources for transmission.

[0825] (4) Information indicating whether to reduce the number of gap symbols or the number of DL symbols.

[0826] (5) Number of intervals after interval reduction.

[0827] (6) Number of DL symbols after DL symbol reduction.

[0828] (7) Symbol number of the increased UL symbol.

[0829] (8) Combinations of the above (1) to (7).

[0830] In the case where an uplink control signal such as Ack / Nack and SRS conflict, time division multiplexing of the uplink control signal and SRS can be performed by setting information related to time division multiplexing.

[0831] In the case of time division multiplexing of the symbol for transmitting SRS and the uplink control signal, information indicating the configuration relationship between the symbol for transmitting SRS and the uplink control signal can be set. For example, information indicating whether the SRS transmission symbol and the symbol mapped with the uplink control signal are continuously configured can be set. In the case of continuous configuration, the signal for changing radio resources is continuously mapped to the signal for not changing radio resources. In the case of discontinuous configuration, the symbol for determining the mapping of the signal for not changing radio resources is notified.

[0832] The cell notifies the UE of the information indicating the configuration relationship. In the case of continuous configuration, sometimes the symbol mapped with the signal for changing radio resources can be derived without using the information related to time division multiplexing. In this case, the cell does not need to notify the UE of the information related to time division multiplexing, and the amount of information required for notification can be reduced.

[0833] The information indicating the configuration relationship can be included in the information related to time division multiplexing. By combining the information indicating the configuration relationship with the information about time division multiplexing and setting, the symbol for time division multiplexing of the uplink control signal and SRS can be set flexibly.

[0834] The information related to time division multiplexing can be statically determined in advance by standards, etc. Both the eNB and the UE can recognize this information. Without the signaling for node - to - node notification, the signaling load can be reduced.

[0835] Alternatively, the eNB can set the information related to time division multiplexing and notify it to the UE. This information can be set for each cell or for each UE. The eNB can include this information in the L1 / L2 control information and notify the UE using the L1 / L2 control signaling. This information can be included in the L1 / L2 control information together with other scheduling information for this UE and notified using the L1 / L2 control signaling. The same method as the method disclosed in Embodiment 3 can be used.

[0836] By using the L1 / L2 control signaling to notify this information, it is possible to make settings in advance. Therefore, a method for time-division multiplexing of the uplink control signal and the SRS can be pre-responded according to, for example, the time variation of the radio wave transmission condition or the speed change of the UE.

[0837] The eNB can notify this information to the UE by using MAC signaling. Since retransmission control is applied, the reception error rate can be reduced. Alternatively, RRC signaling can also be used for notification. When set for each cell, it can be included in the broadcast information for broadcasting. Alternatively, RRC dedicated signaling can also be used to notify each UE. When set for each UE, RRC dedicated signaling can also be used to notify each UE. When using RRC signaling for notification, it can be notified together with the structure information of the SRS. Thus, the signaling load can be reduced.

[0838] By using the method disclosed in this modification example, even when the uplink control signal such as Ack / Nack and the SRS conflict in the same subframe in NR, the UE can send either signal. Therefore, the cell can receive the uplink control signal such as Ack / Nack and the SRS at a predetermined timing. By being able to receive Ack / Nack at a predetermined timing, retransmission control can be performed without delay. In addition, by being able to receive the SRS at a predetermined timing, the cell can perform precoding with higher accuracy.

[0839] In addition, as disclosed in Embodiment 3, there is no need to separately set frequency resources on the basis of the normal SRS, so the required frequency resources can be reduced. In addition, conflicts with resources for which information for other UEs has been scheduled can be avoided, so that the control can be prevented from becoming complicated.

[0840] The case where the uplink control signal and the SRS conflict in the last symbol within one subframe is disclosed, but the uplink control signal and the SRS can also be mapped to other symbols within one subframe. Similarly to the case where a conflict occurs in the other symbol, the method disclosed in this modification example such as time-division multiplexing can be applied. In this case, the same effect as this modification example can also be obtained.

[0841] The case where the uplink control signal and the SRS are mapped to the same symbol and conflict within one subframe is disclosed, but the uplink control signal and the SRS can also be mapped to symbols with different numbers of symbols respectively. Similarly to the case where a conflict occurs in a part of the symbols in this case, the method disclosed in this modification example such as time-division multiplexing can be applied to the symbols where the conflict occurs. In this case, the same effect as this modification example can also be obtained.

[0842] In the same UE, transmission of different uplink control signals in the same subframe sometimes causes conflicts. When conflicts occur in the transmission of different uplink control signals in one or a part of the symbols in the same subframe, the method disclosed in this modification example can also be appropriately applied. For example, when the transmission of Ack / Nack and the transmission of CQI / CSI in a certain UE occur in the same symbol in the same subframe, the UL symbol is increased, and the UE transmits without changing the radio resources for transmitting CQI / CSI, and allocates Ack / Nack to the increased UL symbol for transmission.

[0843] Thereby, even when conflicts occur between Ack / Nack and CQI / CSI in one or a part of the symbols in the same subframe, the UE can transmit both signals in the same subframe. In addition, the cell can receive both signals in the same subframe. In addition, when the symbol of CQI / CSI is configured to be earlier than the symbol of Ack / Nack, in a self-contained subframe, a response of Ack / Nack to downlink data can be transmitted within the same subframe.

[0844] In addition, the number of uplink control signals is not limited to two, and may be three or more. One uplink control signal is transmitted without changing the radio resources, and two uplink control signals are allocated to the increased UL symbol for transmission. The same method as the above method can be applied.

[0845] Thereby, even when conflicts occur between different uplink control signals in one or a part of the symbols in the same subframe, the UE can transmit both signals in the same subframe. In addition, the cell can receive both signals in the same subframe.

[0846] The cell can receive information from the UE in a pre-determined subframe, and thus can perform control on the UE in a timely manner. For example, retransmission control based on Ack / Nack can be performed without delay. In addition, for example, precoding for downlink MIMO based on CQI / CSI can be performed with high accuracy. Or, uplink communication can be started earlier by executing an uplink scheduling request based on SR in advance.

[0847] In the method disclosed above, in the case where there is a conflict between the uplink control signal of Ack / Nack and SRS, the number of UL symbols in the same subframe is increased, the uplink control signal is mapped to the increased UL resources, and time-division multiplexing is performed on the uplink control signal and SRS. As another method for the case where there are already other UL symbols in the same subframe, the uplink control signal can be mapped to the existing UL symbols without increasing the number of UL symbols. In the case where there is no conflict, when UL information is mapped in the existing UL symbols, the UL information is reduced and the uplink control signal can be mapped. The above UL information can be, for example, UL user data. In this case, the same effect as this modification example can also be obtained.

[0848] Thus, in the case of using the existing UL symbols without increasing the number of UL symbols, in the specific example of the above information related to time-division multiplexing, "the symbols of the increased UL" can be read and replaced with "the UL symbols from which other UL information is reduced". The same applies when no other UL information is mapped.

[0849] For a certain UE, in the case where there is a conflict between the SRS symbol and the uplink control signal, the symbol of the SRS can be moved forward, and the symbols of the SRS of other UEs transmitted by this subframe can also be moved forward. The SRS transmission symbol of a certain UE and the SRS transmission symbols of other UEs can be set to be the same. The cell notifies other UEs of the amount of the symbol by which the SRS is moved forward, which is equivalent to the uplink control signal. This notification can use L1 / L2 control signaling.

[0850] In this case, if the number of symbols to which the uplink control signal is mapped is different for each UE, it is necessary to notify each UE of the different number of symbols of the uplink control signal, and the control becomes complex. To solve this problem, the maximum number of symbols used in the uplink control signal can be notified. Even for a UE whose number of symbols for the uplink control signal is less than the maximum number of symbols, the maximum number of symbols for the uplink control signal can be notified. Thus, the same number of symbols of the uplink control signal can be notified to the UE. The complexity of the control can be avoided.

[0851] As another method, the number of symbols to which the uplink control signal is mapped can be set for each cell. The cell notifies the UE of the number of symbols to which the uplink control signal of each cell is mapped by using RRC. Thus, the cell only needs to notify the UE of the case where the SRS is moved forward by using L1 / L2 control signaling. An information indicating that the SRS is moved forward is set, and the cell notifies this information to the UE. There is no need to notify how many symbols have been moved forward.

[0852] It is disclosed that the number of symbols mapped with uplink control signals is set for each cell, but it can also be set not for each cell but for each numerology. Alternatively, it can be set for each frequency band using the same numerology. Alternatively, it can also be set for each UE with the same numerology.

[0853] As numerology, the symbol time interval, sub-carrier spacing, etc. are set. In 3GPP, it is proposed to set different numerologies within the same cell. If these settings are different, the symbol timing and frequency band of SRS become different. In this case, the complexity of the setting can be avoided by making the setting for each numerology.

[0854] In addition, in the case of setting numerology for each UE of the same service, each UE of the same type, and each UE of the same capability, the complexity of the setting can also be avoided.

[0855] For other UEs that do not transmit SRS in the SRS transmission symbol, it can be set not to transmit SRS in the SRS transmission symbol. For other UEs that are scheduled for the uplink channel or uplink signal, the UE that transmits SRS in the SRS transmission symbol can set the case of not transmitting SRS in the RB for SRS transmission in the SRS transmission symbol. The cell can notify this setting to the UE using L1 / L2 control signaling.

[0856] Thereby, the interference to the UE performing SRS transmission can be reduced.

[0857] As the information related to time division multiplexing described above, information such as an increased UL symbol and a UL symbol for reducing other UL information is disclosed, but these are information about the symbol for transmitting SRS.

[0858] Not only can the eNB notify the UE of the information related to the SRS transmitted by the UE, but the eNB can also notify the UE of the information related to the SRS transmitted by other UEs in the same subframe. As the information related to SRS, there is information such as the symbol for transmitting SRS and the RB for transmitting SRS. The eNB can include this information in the L1 / L2 control information and notify it to the UE using L1 / L2 control signaling. The eNB can include this information together with other scheduling information for the UE in the L1 / L2 control information and notify it to the UE using L1 / L2 control signaling.

[0859] When the eNB does not transmit other channels or signals to a UE during the SRS transmission symbol of other UEs, the eNB can set the situation of not transmitting other channels or signals during this SRS transmission symbol and notify this setting to the UE. Alternatively, it can be determined in advance through standards or the like that other channels or signals are not transmitted during the SRS transmission symbol of other UEs, and the UE causes other channels or signals not to be transmitted during the SRS transmission symbol of other UEs.

[0860] Thereby, the interference to the UE performing SRS transmission can be reduced.

[0861] The SRS is set in units of symbols, but a time interval shorter than a symbol can also be used. For example, the SRS can be set in units of 1 / 2 of a symbol.

[0862] Information such as the RB for transmitting the SRS can be set in units of one or more RBs. Alternatively, instead of RBs, subcarrier information can be set in units of one or more subcarriers.

[0863] The eNB can notify the UE of the information related to the SRS transmitted by this UE and / or the information related to the SRS transmitted by other UEs together with the subframe structure of the SRS disclosed in Embodiment 2. Alternatively, the eNB can notify the UE of the information related to the SRS transmitted by this UE and / or the information related to the SRS transmitted by other UEs together with the information for starting SRS transmission. Alternatively, the eNB can notify the UE of the information related to the SRS transmitted by this UE and / or the information related to the SRS transmitted by other UEs together with the information for stopping SRS transmission.

[0864] These pieces of information can be combined appropriately. The combined information can be included in the L1 / L2 control information and notified using the L1 / L2 control signaling. Alternatively, the combined information can be included in the L1 / L2 control information together with other scheduling information for this UE and notified using the L1 / L2 control signaling.

[0865] Thereby, the transmission and stop of the SRS can be set for the UE dynamically and flexibly. The SRS transmission corresponding to the capabilities and conditions of each UE in the cell can be performed.

[0866] Variant Example 2 of Embodiment 3.

[0867] In this variant example, other methods for solving the problems disclosed in Embodiment 3 are disclosed.

[0868] In the case where there is a conflict between SRS and Ack / Nack, SRS can be used to discriminate Ack / Nack. Set an SRS with a sequence different from the sequence number of the SRS set in the normal case, and make the sequence number of the transmitted SRS different according to whether it is Ack or Nack.

[0869] In the case where the transmission of SRS and the transmission of Ack / Nack conflict in a certain UE, for example, use sequences different from the sequence of the SRS of this UE in the normal case for both Ack and Nack. In the case of Ack, transmit an SRS with a sequence different from the sequence of the SRS transmitted by this UE. In the case of Nack, transmit an SRS with a sequence different from the sequence of the SRS transmitted by this UE and different from the sequence of the SRS transmitted in the case of Ack.

[0870] The cell can discriminate whether it is Ack or Nack by receiving the SRS and identifying which sequence is used. In addition, since it is transmitted as SRS, it also has the function of SRS, that is, the uplink sounding function. The cell can obtain the uplink channel state by receiving the SRS.

[0871] As another example, use a sequence different from the sequence of the SRS of this UE in the normal case only in the case of Ack. In the case of Ack, transmit an SRS with a sequence different from the sequence of the SRS transmitted by this UE. In the case of Nack, transmit an SRS with the same sequence as the SRS transmitted by this UE. In other words, transmit the normal SRS of this UE.

[0872] The cell can discriminate whether it is Ack or Nack by receiving the SRS and identifying which sequence is used. In the case where the sequence for Ack is used, it can be identified as Ack. In the case where the normal sequence is used, it can be identified as Nack. Compared with the above example, in this case, there is no need to set a sequence for Nack. Therefore, the number of sequences used can be reduced.

[0873] In the above example, the case of using the sequence number set in SRS is disclosed. As another method, CS (cyclic shift) can also be used. Set an SRS with a CS different from the CS of the SRS set in the normal case, and make the CS of the transmitted SRS different according to whether it is Ack or Nack.

[0874] For example, different CSs from the CS of the normal SRS of this UE are used for both Ack and Nack. In the case of Ack, an SRS with a CS different from the CS of the SRS transmitted by this UE is transmitted. In the case of Nack, an SRS with a CS different from the CS of the SRS transmitted by this UE and different from the CS of the SRS transmitted in the case of Ack is transmitted. The cell can determine whether it is Ack or Nack by receiving the SRS and identifying which CS is used. In addition, since it is transmitted as an SRS, it also has the function of an SRS, that is, the uplink sounding function. The cell can obtain the uplink channel state by receiving the SRS.

[0875] As another example, a CS different from the CS of the normal SRS of this UE is used only in the case of Ack. In the case of Ack, an SRS with a CS different from the CS of the SRS transmitted by this UE is transmitted. In the case of Nack, an SRS with the same CS as the SRS transmitted by this UE is transmitted. In other words, the normal SRS of this UE is transmitted. The cell can determine whether it is Ack or Nack by receiving the SRS and identifying which CS is used. When the CS for Ack is used, it can be identified as Ack. When the normal CS is used, it can be identified as Nack. Compared with the above example, in this case, there is no need to set a CS for Nack. Th...

Claims

1. A communication system, the communication system comprising: A user equipment capable of transmitting sounding reference signals; and a base station wirelessly communicating with the user equipment, wherein the communication system is characterized in that the base station uses RRC signaling to send structure information indicating a plurality of structure settings for the sounding reference signals to the user equipment, the structure settings include information related to the period of the time slot unit for the periodic transmission of the sounding reference signals and information related to an offset, where the offset is the number of time slots from the time slot set as the period to the start of the periodic transmission of the sounding reference signals.

2. The communication system according to claim 1, wherein the base station uses MAC signaling to send information related to the start and stop of the periodic transmission of the sounding reference signals to the user equipment.

3. The communication system according to claim 1, wherein the base station uses L1 / L2 signaling to send offset information for the aperiodic transmission of the sounding reference signals to the user equipment.

4. The communication system according to claim 1, wherein the base station includes a distributed unit wirelessly communicating with the user equipment and an upper node located above the distributed unit, and the upper node sends the structure information to the distributed unit.

5. A base station, which is a base station in a communication system, and the communication system includes: A user equipment capable of transmitting sounding reference signals; and the base station wirelessly communicating with the user equipment, wherein the base station is characterized in that it uses RRC signaling to send structure information indicating a plurality of structure settings for the sounding reference signals to the user equipment, the structure settings include information related to the period of the time slot unit for the periodic transmission of the sounding reference signals and information related to an offset, where the offset is the number of time slots from the time slot set as the period to the start of the periodic transmission of the sounding reference signals.

6. A user device, which is a user device in a communication system, the communication system comprising: The user equipment capable of transmitting sounding reference signals; and a base station wirelessly communicating with the user equipment, wherein the user equipment is characterized in that it transmits the sounding reference signals based on the structure information indicating a plurality of structure settings for the sounding reference signals sent from the base station using RRC signaling, the structure settings include information related to the period of the time slot unit for the periodic transmission of the sounding reference signals and information related to an offset, where the offset is the number of time slots from the time slot set as the period to the start of the periodic transmission of the sounding reference signals.

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