Communication system

Abstract

The present invention relates to a communication system. The PDSCH of a conventional UE is mapped to physical resources in units of subframes, and the PDSCH of an LR-UE is mapped to a region of physical resources where the PDSCH of the conventional UE is mapped, in units of physical resource blocks (PRBs) that make up a subframe. In addition, the PDSCH of the conventional UE is mapped to physical resources in units of PRB pairs (30) composed of two PRBs (31, 32), and the PDSCH of the LR-UE is mapped to the remaining physical resources other than the PRB pair (30) where the PDSCH of the conventional UE is mapped.

Description

[0001] This application is a divisional application of an application with an application date of "May 24, 2016", an application number of "201680045347.5", 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 standardization body of the mobile communication system, namely 3GPP (3rd Generation Partnership Project), 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, refer to Non-Patent Documents 1 to 12 and Patent Document 1). This communication method is also called a 3.9G (3.9th generation) system.

[0004] As an access method of 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, different from W-CDMA (Wideband Code division Multiple Access), LTE does not include circuit switching and is only a packet communication method.

[0005] Use Figure 1 Describe the decisions 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 and sixth subframes of each radio frame contain downlink synchronization signals. The synchronization signal has a primary synchronization signal (P-SS) and a secondary synchronization signal (S-SS).

[0006] In Non-Patent Document 1 (Chapter 5), matters related to the channel structure of the LTE system in 3GPP are described. 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 a base station to a communication terminal. The PCFICH notifies a communication terminal from a 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 an Ack (Acknowledgement) / Nack (Negative Acknowledgement), which is a response signal for uplink transmission. The PDCCH is also referred to as an 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 DL-SCH, which is a transmission channel, and the PCH, which is 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), which is a transmission channel, is mapped to 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 an ACK / Nack, which is a response signal for 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 PUSCH is mapped with the Uplink Shared Channel (UL-SCH), which is one of the transport channels.

[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 an LTE-based communication system. 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, i.e., the Demodulation Reference Signal (DM-RS), 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. Among the downlink transport channels, the Broadcast Channel (BCH) is broadcast over the entire coverage area of its base station (cell). The BCH is mapped to the Physical Broadcast Channel (PBCH).

[0017] Retransmission control using HARQ (Hybrid ARQ) is applied to the Downlink Shared Channel (DL-SCH). The DL-SCH can be broadcast over the entire coverage area of the 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 the 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 the communication terminal in order to enable low power consumption of the communication terminal. The PCH is required to be broadcast over the entire coverage area of the base station (cell). The PCH is mapped to physical resources such as the Physical Downlink Shared Channel (PDSCH) that can be dynamically utilized for services.

[0019] The Multicast Channel (MCH) is used to broadcast over the entire coverage area of the base station (cell). The MCH supports SFN synthesis of the 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] Retransmission control using HARQ (Hybrid ARQ) is applied 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 by control information. There is a risk of collision in the RACH. The RACH is mapped to the Physical Random Access Channel (PRACH).

[0022] The following describes HARQ. HARQ is a technology that improves the communication quality of a transmission line by combining Automatic Repeat Request (ARQ) and Forward Error Correction. The advantage of HARQ is that even for a transmission line with changing communication quality, retransmission can be used to effectively perform error correction. In particular, when retransmission is performed, the quality can be further improved by combining the reception results of the first transmission and the retransmission.

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

[0024] The logical channel described in Non-Patent Document 1 (Chapter 6) is described. 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 transmitting 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 transmitting control information between a communication terminal and a base station. The CCCH is used in the following cases: that is, 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 used 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 by communication terminals that are receiving MBMS. The MCCH is mapped to the Multicast Channel (MCH) which is a transport channel.

[0028] The Dedicated Control Channel (DCCH) is a channel used to send 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 used to send user information and perform point-to-point communication with 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 used to send service data from the network to the communication terminal. The MTCH is a channel only used by communication terminals that are receiving MBMS. The MTCH is mapped to the Multicast Channel (MCH).

[0031] CGI stands for Cell Global Identifier. ECGI stands for E-UTRAN Cell Global Identifier. In LTE, the subsequent LTE-A (Long Term Evolution - Advanced), and UMTS (Universal Mobile Telecommunication System), Closed Subscriber Group (CSG) cells have been introduced.

[0032] A CSG (Closed Subscriber Group) cell is a cell for subscribers who are specifically authorized by an operator to use it (hereinafter sometimes referred to as "cell for specific subscribers"). Specific subscribers are permitted to access one or more cells of a PLMN (Public Land Mobile Network). One or more cells that permit specific subscribers to access are called "CSG cells (CSG cell(s))". However, there are access restrictions in the PLMN.

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

[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, to make it easier for members associated with the CSG to access, 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 performed to track the location of the communication terminal even in the standby state and to communicate with the communication terminal, in other words, 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] Each mode has the following characteristics. In the open access mode, the HeNB and HNB are operated as regular cells for normal operators. In the closed access mode, the HeNB and HNB are operated as CSG cells. The CSG cell is a CSG cell that only CSG members can access. In the hybrid access mode, the HeNB and HNB are operated as CSG cells to which non-CSG members are also allowed to access. In other words, the cell in the hybrid access mode (also called a hybrid cell) is a cell that supports both the open access mode and the closed access mode.

[0038] In 3GPP, there is a range of Physical Cell Identities (PCI) reserved by the network for use by CSG cells among all physical cell identities (refer to Section 10.5.1.1 of Non-Patent Document 1). Sometimes the situation of splitting the PCI range is called PCI splitting. Information related to PCI splitting (also called PCI splitting information) is broadcast from the base station to mobile terminals within its coverage area through system information. Being covered by the base station means using this base station as the serving cell.

[0039] Non-Patent Document 3 discloses the basic operations of a communication terminal using PCI splitting. A communication terminal without PCI splitting information needs to use all PCIs, for example, use all 504 codes to perform cell search. In contrast, a communication terminal with PCI splitting information can use this PCI splitting information to perform cell search.

[0040] In addition, in 3GPP, as Release 10, the standardization of Long Term Evolution Advanced (LTE-A) is continuously evolving (refer to Non-Patent Documents 4 and 5). LTE-A is based on the radio access mode of LTE and is constituted by adding some new technologies to it.

[0041] In the LTE-A system, in order to support a wider bandwidth (transmission bandwidths) of up to 100 MHz, Carrier Aggregation (CA) that aggregates two or more Component Carriers (CC) (also called "aggregation") has been studied.

[0042] In the case of forming a CA, the UE has a unique RRC connection with the network (NW). In the RRC connection, one serving cell provides NAS mobility information and security inputs. This cell is called the Primary Cell (PCell). In the downlink, the carrier corresponding to the PCell is the Downlink Primary Component Carrier (DLPCC). In the uplink, the carrier corresponding to the PCell is the Uplink Primary Component Carrier (ULPCC).

[0043] According to the UE's capability, a Secondary Cell (SCell) is formed 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 (DLSCC). In the uplink, the carrier corresponding to the SCell is the Uplink Secondary Component Carrier (ULSCC).

[0044] For one UE, a group of serving cells is formed consisting of one PCell and one or more SCells.

[0045] In addition, as new technologies of LTE-A, there are technologies such as Wider bandwidth extension and Coordinated Multiple Point transmission and reception (CoMP). Regarding CoMP studied for implementing LTE-A in 3GPP, it is described in Non-Patent Document 6.

[0046] The traffic volume of the mobile network has an increasing trend, 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.

[0047] Therefore, in accordance with the requirement of improving the data transmission speed, 3GPP is studying the reduction of latency (refer to Non-Patent Document 7). As a method for reducing latency, a scheme has been proposed to shorten the Transmission Time Interval (TTI) for a UE in the connected state. It has been proposed to set the current LTE standard case of TTI = 1 subframe to, for example, TTI = 1 time slot, or TTI = 1 symbol. 1 subframe is 1 ms, 1 time slot is 0.5 ms, and 1 symbol is 0.1 ms.

[0048] The operation method when the TTI is shortened is described in Patent Document 1.

[0049] Prior Art Documents

[0050] Non-Patent Documents

[0051] Non-Patent Document 1: 3GPP TS36.300 V13.0.0

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

[0053] Non-Patent Document 3: 3GPP R2-082899

[0054] Non-Patent Document 4: 3GPP TR36.814 V9.0.0

[0055] Non-Patent Document 5: 3GPP TR36.912 V10.0.0

[0056] Non-Patent Document 6: 3GPP TR36.819 V11.2.0

[0057] Non-Patent Document 7: 3GPP RP-150465

[0058] Non-Patent Document 8: 3GPP TS36.141 V13.0.0

[0059] Non-Patent Document 9: 3GPP TS36.211 V12.6.0

[0060] Non-Patent Document 10: 3GPP TS36.212 V12.5.0

[0061] Non-Patent Document 11: A. Roessler, M. Kottkamp, "Introduction to LTE Evolution (3GPP Rel.11) Technology", White Paper, Rohde & Schwarz Japan, July 2013, 1MA232_1J

[0062] Non - Patent Document 12: 3GPP TS36.213 V12.6.0

[0063] Patent Document

[0064] Patent Document 1: Japanese Patent Laid - Open No. 2009 - 212597 Summary of the Invention

[0065] Technical Problem to be Solved by the Invention

[0066] TTI is a unit of transmission time. Data is scheduled for each TTI, mapped to physical resources and transmitted. For example, in the case of TTI = 1 sub - frame which is the current standard, it is determined that data scheduling and physical resource mapping are performed during 1 sub - frame. Therefore, the current standard does not support shortened TTI.

[0067] On the current LTE carrier, without consuming any effort, it is difficult to simultaneously support legacy UEs corresponding to the existing TTI standard and UEs corresponding to the new shortened TTI (hereinafter referred to as "LR - UEs"), that is, it is difficult to have backward compatibility. In 3GPP, no discussion has been made on these issues.

[0068] Although the above - mentioned Patent Document 1 describes the case of shortened TTI, it still discloses a method configured in units of TTI = 1 sub - frame. That is, it is the same as the existing sub - frame - unit scheduling. Therefore, Patent Document 1 does not disclose support for shortened TTI, such as TTI = 1 time slot and TTI = 1 symbol, etc. In addition, in order to support shortened TTI on the same LTE carrier, it is necessary to strive for the co - existence of LR - UEs and legacy UEs. Patent Document 1 does not disclose how to map and transmit these two types of data, namely the existing TTI and the shortened TTI, within 1 sub - frame.

[0069] An object of the present invention is to provide a communication system that can cope with various transmission time intervals and has backward compatibility.

[0070] Technical Solution for Solving the Technical Problem

[0071] The communication system of the present invention includes a plurality of communication terminal devices and a base station device capable of wireless communication with each of the communication terminal devices. It is characterized in that the plurality of communication terminal devices include a first communication terminal device and a second communication terminal device. The first communication terminal device sets the transmission time interval with the base station device to 1 subframe, and the second communication terminal device sets the transmission time interval to be shorter than 1 subframe. In the first communication terminal device, the shared channel mapped with data is mapped to the physical resource in units of subframes. In the second communication terminal device, the shared channel is mapped to the area of the physical resource where the shared channel of the first communication terminal device is mapped in units of physical resource blocks constituting the subframe.

[0072] Advantages of the Invention

[0073] In the communication system according to the present invention, the shared channel of the first communication terminal device is mapped to the physical resource in units of subframes. The shared channel of the second communication terminal device is mapped to the area of the physical resource where the shared channel of the first communication terminal device is mapped in units of physical resource blocks. Thus, the shared channel of the second communication terminal device can be mapped to the physical resource according to the transmission time interval. In addition, the shared channel of the first communication terminal device and the shared channel of the second communication terminal device can coexist in the physical resource within one subframe. Therefore, a communication system that can cope with various transmission time intervals and has backward compatibility can be realized.

[0074] The objectives, features, aspects, and advantages of the present invention will become more apparent through the following detailed description and drawings. 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 mode.

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

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

[0078] Figure 4 It is a block diagram showing the structure of the 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 6It is a flowchart showing an overview of the actions of a communication terminal (UE) from cell search to standby in a communication system using the LTE mode.

[0081] Figure 7 It is a diagram showing the concept of the cell structure in the case where macro eNBs and small eNBs coexist.

[0082] Figure 8 It is a diagram for explaining the mapping of an existing PDSCH to physical resources.

[0083] Figure 9 It is a diagram for explaining the mapping of the PDSCH of the LR-UE in Embodiment 1 to physical resources.

[0084] Figure 10 It is a diagram for explaining the PDCCH per time slot in Embodiment 1.

[0085] Figure 11 It is a diagram for explaining the mapping method in Embodiment 1.

[0086] Figure 12 It is a diagram for explaining the mapping method of Modification Example 1 of Embodiment 1.

[0087] Figure 13 It is a diagram for explaining another example of the mapping method of Modification Example 1 of Embodiment 1.

[0088] Figure 14 It is a diagram for explaining the scheduling method of Modification Example 2 of Embodiment 1.

[0089] Figure 15 It is a diagram for explaining the scheduling method of Modification Example 2 of Embodiment 1.

[0090] Figure 16 It is a diagram for explaining the scheduling method of Modification Example 3 of Embodiment 1.

[0091] Figure 17 It is a diagram for explaining the scheduling method of Modification Example 4 of Embodiment 1.

[0092] Figure 18 It is a diagram for explaining the scheduling method of Modification Example 5 of Embodiment 1.

[0093] Figure 19 It is a diagram for explaining the transmission method of Modification Example 6 of Embodiment 1.

[0094] Figure 20 It is a diagram for explaining the transmission method of Modification Example 6 of Embodiment 1.

[0095] Figure 21 It is a diagram for explaining the transmission method of the LR-PHICH in Embodiment 2.

[0096] Figure 22 This is a diagram for explaining the transmission method of LR-PHICH in Embodiment 2.

[0097] Figure 23 This is a diagram for explaining the method of multiplexing Ack / Nack into the LR-EPDCCH region and transmitting it in Embodiment 2.

[0098] Figure 24 This is a diagram for explaining the method of multiplexing Ack / Nack into the LR-EPDCCH region and transmitting it in Embodiment 2.

[0099] Figure 25 This is a diagram for explaining the mapping of existing PUSCH and PUCCH to physical resources.

[0100] Figure 26 This is a diagram for explaining the mapping of PUSCH of LR-UE to physical resources in Embodiment 3.

[0101] Figure 27 This is a diagram for explaining the mapping of PUCCH of LR-UE to physical resources in Embodiment 4.

[0102] Figure 28 This is a diagram for explaining other mapping methods of the mapping of PUCCH of LR-UE to physical resources in Embodiment 4.

[0103] Figure 29 This is a diagram for explaining the configuration method of SRS of LR-UE in Embodiment 5.

[0104] Figure 30 This is a diagram for explaining the configuration method of SRS of LR-UE in Embodiment 5.

[0105] Figure 31 This is a diagram for explaining the transmission method of PDCCH and PDSCH for each symbol of LR-UE in Embodiment 6.

[0106] Figure 32 This is a diagram for explaining other examples of PDCCH and PDSCH for each symbol of LR-UE in Embodiment 6.

[0107] Figure 33 This is a diagram for explaining the transmission method in Embodiment 6.

[0108] Figure 34 This is a diagram for explaining other methods of constructing LR-PDSCH in Embodiment 6.

[0109] Figure 35It is a diagram for explaining the PUSCH transmission method for each symbol of the LR-UE in Embodiment 8.

[0110] Figure 36 It is a diagram for explaining the method of multiplexing and transmitting the PUSCHs of multiple LR-UEs within one symbol in Embodiment 8.

[0111] Figure 37 It is a diagram for explaining the mapping method in Embodiment 8.

[0112] Figure 38 It is a diagram for explaining the mapping of the PUCCH of the LR-UE in each symbol to physical resources in Embodiment 9.

[0113] Figure 39 It is a diagram for explaining the configuration method of the SRS of the LR-UE in Embodiment 10.

[0114] Figure 40 It is a diagram for explaining the method of multiplexing and transmitting the SRS of the LR-UE with the PUSCH in Embodiment 10.

[0115] Figure 41 It is a diagram showing an example of the related process for TTI switching for the LR-UE in Embodiment 11.

[0116] Figure 42 It is a diagram showing an example of the related process for TTI switching for the LR-UE in Embodiment 11.

[0117] Figure 43 It is a diagram showing an example of the related process for TTI switching for the LR-UE in Embodiment 11.

[0118] Figure 44 It is a diagram showing another example of the related process for TTI switching for the LR-UE in Embodiment 11.

[0119] Figure 45 It is a diagram showing another example of the related process for TTI switching for the LR-UE in Embodiment 11.

[0120] Figure 46 It is a diagram showing another example of the related process for TTI switching for the LR-UE in Embodiment 11.

[0121] Figure 47 It is a diagram showing an example of the related process for the processing of supporting multiple TTIs for one LR-UE simultaneously in Embodiment 12.

[0122] Figure 48This is a diagram showing an example of the related process for supporting multiple TTIs for one LR-UE in Embodiment 12.

[0123] Figure 49 This is a diagram showing an example of the related process for supporting multiple TTIs for one LR-UE in Embodiment 12.

[0124] Figure 50 This is a diagram showing an example of the related process for the S-eNB to notify the LR-UE to release the shortened TTI during HO in Embodiment 16.

[0125] Figure 51 This is a diagram showing an example of the related process for the S-eNB to notify the LR-UE to release the shortened TTI during HO in Embodiment 16. Detailed implementation manners

[0126] Embodiment 1

[0127] Figure 2 This is a block diagram showing the overall structure of the communication system 200 of the LTE mode discussed in 3GPP. An explanation is given as follows. The radio access network is called E-UTRAN (Evolved Universal Terrestrial Radio Access Network) 201. The communication terminal device, that is, the mobile terminal device (hereinafter referred to as "mobile terminal (User Equipment: UE)") 202 can perform wireless communication with the base station device (hereinafter referred to as "base station (E-UTRAN NodeB: eNB)") 203, and use wireless communication to transmit and receive signals. Figure 2 Here, the "communication terminal device" not only refers 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".

[0128]

[0129] ​If the control protocols for the mobile terminal 202, such as RRC (Radio Resource Control), and the user planes, 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.

[0130] 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.

[0131] In RRC_IDLE, PLMN (Public Land Mobile Network) selection, broadcast of system information (SI), paging, cell re-selection, mobility, etc. are performed. In RRC_CONNECTED, the mobile terminal has an RRC connection and can send and receive data with the network. In addition, in RRC_CONNECTED, handover (HO), measurement of neighbour cells, etc. are performed.

[0132] The base station 203 is classified into eNB207 and Home-eNB206. The communication system 200 includes an eNB group 203-1 containing multiple eNB207s and a Home-eNB group 203-2 containing multiple Home-eNB206s. The system composed of the EPC (Evolved Packet Core) as the core network and the E-UTRAN201 as the radio access network is called the EPS (Evolved Packet System). Sometimes the EPC as the core network and the E-UTRAN201 as the radio access network are collectively referred to as the "network".

[0133] The eNB 207 is connected to a Mobility Management Entity (MME), or 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. One eNB 207 can be connected to multiple MME units 204. The eNBs 207 are connected to each other via the X2 interface and communicate control information therebetween.

[0134] 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. One MME unit 204 is connected to multiple Home-eNBs 206. 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.

[0135] 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.

[0136] 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 a mobile terminal (UE) 202. The MME unit 204 constitutes an Evolved Packet Core (EPC) as the core network. The base station 203 and the HeNBGW 205 constitute an Evolved Universal Terrestrial Radio Access Network (E-UTRAN) 201.

[0137] Furthermore, the following structure has been studied in 3GPP. 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.

[0138] Whether the 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 the Home-eNB 206 and the MME unit 204 is the S1 interface in the same way.

[0139] The base station 203 can form one cell or multiple cells. Each cell has a predetermined range as the coverage range within which it can communicate with the mobile terminal 202, 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.

[0140] 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 to the transmission data buffer unit 303. The data saved in the transmission data buffer unit 303 is transmitted to the encoder unit 304 for 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 undergoing encoding processing. The data after the encoding processing 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, a transmission signal is transmitted from the antenna 307 to the base station 203.

[0141] 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 subjected to demodulation processing in the demodulation unit 308. The demodulated data is transmitted to the decoding unit 309 for decoding processing such as error correction. The control data in the decoded 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. Therefore, although it is omitted in Figure 3 , the control unit 310 is connected to each of the units 301 to 309.

[0142] Figure 4 It represents the base station related to the present invention, that is Figure 2 a block diagram showing the structure of 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, as well as 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.

[0143] The data stored in the transmission data buffer unit 404 is transmitted to the encoder unit 405 for 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 undergoing encoding processing. The encoded data undergoes 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 to be converted into a radio transmission frequency. Subsequently, a transmission signal is transmitted to one or more mobile terminals 202 using the antenna 408.

[0144] In addition, the reception processing of the base station 203 is performed as follows. A 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 undergoes demodulation processing in the demodulation unit 409. The demodulated data is transmitted to the decoding unit 410 for decoding processing such as error correction. The control data in the decoded 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 processes of the base station 203 are controlled by the control unit 411. Therefore, although it is omitted in Figure 4 the control unit 411 is connected to each of the units 401 to 410.

[0145] Figure 5 is a block diagram showing the structure of the MME according to the present invention. Figure 5 The above is shown in 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 using 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 to the base station communication unit 502 via the user plane communication unit 503 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 to the PDN GW communication unit 501 via the user plane communication unit 503 and is sent to the PDN GW.

[0146] 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.

[0147] The HeNB GW communication unit 504 is provided when there is a HeNB GW 205 and performs data transmission and reception using the interface (IF) between the MME 204a and the HeNB GW 205 according to the type of information. The control data received from the HeNB GW communication unit 504 is transmitted from the HeNB GW communication unit 504 to the control plane control unit 505. The processing result of 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, and is sent to one or more HeNB GWs 205 via the HeNB GW communication unit 504.

[0148] 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 on the control plane. The NAS security unit 505-1 is responsible for the security of NAS (Non-Access Stratum) messages, etc. The SAE bearer control unit 505-2 performs management of SAE (System Architecture Evolution) bearers, etc. The idle state mobility management unit 505-3 performs mobility management in the standby state (also referred to as the idle state; LTE-IDLE state, or simply idle), generation and control of paging signals in the standby state, addition, deletion, update, retrieval, tracking area list management, etc. of the tracking areas of one or more mobile terminals 202 within the coverage area.

[0149] MME204a allocates paging signals to one or more base stations 203. MME204a performs mobility control in the Idle State. MME204a manages the Tracking Area list when the mobile terminal is in the standby state and the Active State. MME204a starts the paging protocol by sending a paging message to a cell belonging to the Tracking Area registered by the UE. The management of the CSG of the Home-eNB206 connected to MME204a, the management of the CSG ID, and the white list management can be performed by the idle state mobility management unit 505-3.

[0150] Next, an example of a cell search method in a communication system is shown. 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 mode. 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) transmitted from surrounding base stations to obtain synchronization of the time slot timing and the frame timing.

[0151] The P-SS and S-SS are collectively referred to as the 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 that the number of PCI is 504. Synchronization is obtained using the 504 PCI, and the PCI of the cell for which synchronization is obtained is detected (determined).

[0152] Next, in step ST602, the cell-specific reference signal (CRS), which is the reference signal (RS) transmitted from the base station to each cell for the 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 coding corresponding one-to-one to the PCI. This coding obtains correlation so that it can be separated from other cells. The coding for the RS of this cell is derived from the PCI determined in step ST601, so that the RS can be detected and the received power of the RS can be measured.

[0153] Next, in step ST603, select, from among one or more cells detected up to step ST602, the cell with the best reception quality of the RS, for example, the cell with the highest reception power of the RS, that is, the best cell.

[0154] Next, in step ST604, receive the PBCH of the best cell to obtain the broadcast information, that is, the BCCH. The BCCH mapped on the PBCH contains the MIB (Master Information Block) including cell structure information. Therefore, by receiving the PBCH and obtaining the BCCH, the MIB can be obtained. As information of the MIB, for example, there are DL (downlink) system bandwidth (also referred to as transmission bandwidth configuration: dl - bandwidth), the number of transmission antennas, SFN (System Frame Number), etc.

[0155] Next, in step ST605, based on the cell structure information of the MIB, receive the DL - SCH of this cell and obtain SIB (System Information Block) 1 in the broadcast information BCCH. SIB1 contains information related to accessing this cell, information related to cell selection, and scheduling information of other SIBs (SIBk; k is an integer greater than or equal to 2). In addition, SIB1 contains the Tracking Area Code (TAC).

[0156] 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 saved by the communication terminal. The tracking area list is also referred to as the TAI list. TAI is identification information for identifying a tracking area and is composed of MCC (Mobile Country Code), MNC (Mobile Network Code), and TAC (Tracking Area Code). MCC is the country code. MNC is the network code. TAC is the code number of the tracking area.

[0157] When the result obtained by comparison in step ST606 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. If the comparison result is that the TAC received in step ST605 is not included in the tracking area list, the communication terminal requests the core network (Core Network, EPC) including the MME, etc. to change the tracking area through this cell to perform TAU (Tracking Area Update).

[0158] 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.

[0159] Due to the popularization of smart phones and tablet terminal devices, the services using cellular wireless communication have grown explosively, which makes people worry about the shortage of wireless resources in the world. In response, in order to improve the frequency utilization efficiency, research on cell miniaturization and the development of spatial separation have been carried out.

[0160] In the existing cell structure, the cell composed of eNBs has a relatively wide coverage range. In the past, cells were configured in such a way that a certain area was covered by using the relatively wide coverage ranges of multiple cells composed of multiple eNBs.

[0161] When the cell is miniaturized, the cell composed of eNBs has a narrower coverage range compared to the coverage range of the cell composed of the existing eNBs. Therefore, the same as the prior art, in order to cover a certain area, a large number of eNBs after cell miniaturization are required compared to the existing eNBs.

[0162] In the following description, a cell with a relatively large coverage range like the cell composed of the existing eNBs is referred to as a "macro cell", and the eNB constituting the macro cell is referred to as a "macro eNB". In addition, a cell with a relatively small coverage range like the cell after cell miniaturization is referred to as a "small cell", and the eNB constituting the small cell is referred to as a "small eNB".

[0163] The macro eNB can be, for example, the "Wide Area Base Station" described in Non-Patent Document 7.

[0164] A small eNB can be, for example, a low-power node, a local node, a hotspot, etc. A small eNB can be a pico eNB that forms a pico cell, a femto eNB that forms 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). A small eNB can be a "Local Area BaseStation" or a "Home Base Station" described in Non-Patent Document 7.

[0165] Figure 7 FIG. is a diagram showing a concept of a cell structure in a case where a macro eNB and a small eNB coexist. 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).

[0166] In a case where multiple eNBs coexist, the coverage area of a cell formed by a certain eNB may be included in the coverage area of a cell formed by another eNB. Figure 7 In the cell structure shown, as indicated by reference numeral "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.

[0167] As indicated by reference numeral "705", there is also a case where the coverage areas 702 of multiple, for example, two small cells are included in the coverage area 701 of one macro cell. The mobile terminal (UE) 703 is included in the coverage area 702 of the small cell and communicates via the small cell.

[0168] In Figure 7 In the cell structure shown, as indicated by reference numeral "706", there is a case where the coverage area 701 of the macro cell formed by the macro eNB and the coverage area 702 of the small cell formed by the small eNB are complexly repeated.

[0169] In addition, as indicated by reference numeral "707", there is also a case where the coverage area 701 of the macro cell formed by the macro eNB and the coverage area 702 of the small cell formed by the small eNB do not overlap.

[0170] Further, as indicated by reference numeral "708", the following situation also occurs, that is, the coverage areas 702 of a plurality of small cells composed of a plurality of small eNBs are formed within the coverage area 701 of a macro cell composed of one macro eNB.

[0171] In accordance with the requirement of improving the data transmission speed, 3GPP is studying the reduction of the latency time (refer to Non-Patent Document 7). As a method for reducing the latency time, a scheme of shortening the Transmission Time Interval (TTI) for a UE in the connected state has been proposed. It is proposed to set the case where TTI = 1 subframe in the current LTE standard to, for example, TTI = 1 time slot, or TTI = 1 symbol. 1 subframe is 1 ms, 1 time slot is 0.5 ms, and 1 symbol is 0.1 ms.

[0172] TTI is a unit of the transmission time. Data is scheduled for each TTI, mapped to physical resources, and transmitted. For example, in the case where the current standard is TTI = 1 subframe, it is determined that data scheduling and physical resource mapping are performed during the period of 1 subframe. Therefore, the current standard does not support the shortened TTI.

[0173] On the current LTE carrier, it is difficult to support both a legacy UE corresponding to the existing TTI standard and a UE corresponding to the new shortened TTI (hereinafter referred to as "LR-UE") without any effort, that is, it is difficult to have backward compatibility. In 3GPP, no discussion has been made on these issues.

[0174] In the present embodiment, a method for solving this problem is disclosed.

[0175] The PDSCH is disclosed. The shared channel, i.e., the PDSCH, to which data of a legacy UE is mapped, is mapped to physical resources in units of subframes. In the current LTE standard, the PDSCH of a legacy UE is mapped to physical resources in the form of a PRB pair (PRB pair). However, the existing PDSCH is not mapped to the PDCCH region.

[0176] A PRB is a Physical Resource Block, which is composed of 12 subcarriers in the frequency axis direction and 1 time slot of physical resources in the time axis direction. A PRB pair is composed of 2 PRBs on the time axis (refer to Non-Patent Document 9).

[0177] Figure 8 is a diagram for explaining the mapping of the existing PDSCH to physical resources. Figure 8 In, the horizontal axis represents the time t, and the vertical axis represents the frequency f.

[0178] Figure 8 In the example shown, 1 time slot consists of 7 symbols. Therefore, 1 subframe consists of 14 symbols. PDCCH is mapped to the first 3 symbols of 1 subframe. PDSCH is mapped after the first 4 symbols. 1 PRB consists of the physical resources of 12 subcarriers in the vertical axis, i.e., the frequency axis direction, and 1 time slot in the horizontal axis, i.e., the time axis direction. Figure 8 In [the figure], they are denoted by reference numerals "11", "12", "21", and "22".

[0179] As Figure 8 shown, the existing PDSCH is mapped to a PRB pair consisting of 2 PRBs of 2 time slots. However, the existing PDSCH is not mapped to the PDCCH area. In Figure 8 the example shown, the first subframe, i.e., subframe #1, is mapped to the PRB pair 10 consisting of PRBs 11 and 12 with the same frequency area. The second subframe, i.e., subframe #2, is mapped to the PRB pair 20 consisting of PRBs 21 and PRB 22 with different frequency areas between time slots. That is, frequency hopping occurs.

[0180] In addition, PDSCH is scheduled using PDCCH. PDCCH is mapped to the PDCCH area. That is, the physical resources mapped with PDSCH are scheduled in units of PRB pairs. In terms of time, scheduling is performed in units of 1 subframe.

[0181] However, the TTI of a UE (LR-UE) that operates with a shortened TTI is shorter than 1 subframe. Therefore, the mapping of its PDSCH to physical resources cannot apply the mapping method of traditional UEs and requires some new method.

[0182] Patent Document 1 describes an operation method when the TTI is shortened. However, although Patent Document 1 describes the case of shortening the TTI, it still discloses a method configured in units of TTI = 1 subframe. That is, it is the same as the existing subframe unit scheduling. Therefore, support for shortened TTIs such as TTI = 1 time slot and TTI = 1 symbol is not disclosed in Patent Document 1. In addition, in order to support a shortened TTI on the same carrier of LTE, it is necessary to strive for the coexistence of LR-UE and traditional UEs. Patent Document 1 does not disclose how to map and transmit the two types of data, the existing TTI and the shortened TTI, within 1 subframe.

[0183] In order to support a shortened TTI on the same carrier of LTE, a method to solve the above problems is needed. The present invention discloses a solution to the above problems.

[0184] In this embodiment, the PDSCH of the LR-UE is mapped to the physical resource region where the existing PDSCH is mapped in units of PRBs. One or more PRBs can be used for one PDSCH.

[0185] The PDSCH of the LR-UE is mapped while avoiding the PRB pairs where the PDSCH of the legacy UE is mapped.

[0186] The PDSCH of the LR-UE is mapped to the symbols other than the symbols where the existing PDCCH is mapped.

[0187] Figure 9 It is a diagram for explaining the mapping of the PDSCH of the LR-UE in Embodiment 1 to the physical resource. As Figure 9 shown, the legacy UE is mapped in units of two PRBs 31, 32, that is, the PRB pair represented by the reference numeral "30". The LR-UE is mapped in units of one PRB. LR-UE#1 and LR-UE#3 are only mapped to the first time slot, i.e., time slot #0. LR-UE#2 is only mapped to the second time slot, i.e., time slot #1. The PRBs where the PDSCH is not scheduled can be generated in units of PRBs. For example, the PDSCH is not scheduled in the PRB shown by the reference numeral "33". The PDSCH is mapped to the physical resource in the region other than the PDCCH region. Thus, the PDCCH region in the PRB is removed from the region where the PDSCH etc. are mapped. Therefore, Figure 9 in the subsequent diagrams, the region where the PDSCH etc. are mapped is shown as a PRB.

[0188] By mapping the PDSCH of the LR-UE to the physical resource using the above method, the PDSCH of the LR-UE can be mapped to the physical resource for each TTI. Also, the PDSCH of the legacy UE and the PDSCH of the LR-UE can be mapped together to the physical resource within one subframe.

[0189] The PDCCH will be described. The existing scheduling is performed in units of subframes. The PDSCH of the legacy UE is scheduled in units of subframes and allocated to the physical resource in units of subframes. The control information for scheduling is included in the Downlink Control Information (DCI) and is mapped to the PDCCH. The PDCCH is mapped to the first 1 to 4 symbols at the start of each subframe. How many of the 1 to 4 symbols are used is indicated by the PCFICH. The PDCCH is only mapped to the first time slot within one subframe (refer to Non-Patent Documents 9 and 10).

[0190] However, the TTI of the LR-UE is shorter than 1 subframe, and the allocated physical resources are also shorter than 1 subframe. Therefore, the existing scheduling method based on subframes cannot be applied. That is, scheduling cannot be performed using the PDCCH of each subframe.

[0191] In addition, in order to support the shortened TTI on the same carrier of LTE, it is necessary to strive for the coexistence of LR-UEs and traditional UEs. The method for solving the above problems is disclosed below.

[0192] For the LR-UE, scheduling of data for each shortened TTI is performed. For the PDSCH of the LR-UE, scheduling is performed for each shortened TTI. When TTI = 1 time slot, scheduling is performed in time slot units. For the PDSCH of the LR-UE, allocation to physical resources is performed in time slot units.

[0193] The PDCCH of each time slot is set. Scheduling of each TTI data is performed using the PDCCH of each time slot. Scheduling in time slot units is performed using the PDCCH of each time slot.

[0194] The downlink control information (DCI) of each time slot is included in the PDCCH. The DCI includes downlink (DL) scheduling information, uplink (UL) scheduling information, etc. The scheduling information includes physical resource allocation information, MCS (Modulation and Coding Scheme) information, etc.

[0195] Similar to the existing PDCCH, the physical resource region of the PDCCH of each time slot is set in one or more symbols within the time slot in the entire system bandwidth. The PDCCH of each time slot in the first time slot within the subframe can be mapped avoiding the symbols where the existing PDCCH is mapped. Thus, conflicts with the existing PDCCH can be avoided.

[0196] Mapping can start from the next symbol immediately following the symbol where the existing PDCCH is mapped. Thus, the physical resource region of the PDCCH can be continuous in time.

[0197] The PDCCH of each time slot in the second time slot within the subframe can be mapped starting from the first symbol within the time slot.

[0198] The mapping method for mapping the PDCCH to physical resources can apply the same method as the existing PDCCH.

[0199] The PCFICH for each time slot can also be set. The PCFICH for each time slot indicates the number of symbols used by the PDCCH for each time slot. It can be mapped to the starting symbol of the region where the PDCCH for each time slot is mapped. The mapping method for mapping the PCFICH for each time slot to physical resources can be the same as the existing PCFICH method.

[0200] Use the PCFICH for each time slot to represent the number of symbols of the PDCCH mapped for each time slot. The LR-UE can identify the number of symbols of the PDCCH for each time slot by receiving the PCFICH for each time slot.

[0201] Figure 10 It is a diagram for explaining the PDCCH for each time slot in Embodiment 1. It shows the case where the existing PDCCH is mapped to the first 2 symbols of 1 subframe indicated by the reference numeral "40". The PDCCH for the LR-UE is mapped to each time slot. In the first time slot #0 within the subframe, the PDCCH for the LR-UE is mapped to the 3rd symbol indicated by the reference numeral "41". In the second time slot #1 within the subframe, the PDCCH for the LR-UE is mapped to the 1st symbol indicated by the reference numeral "42". In the first time slot #0 within the subframe, the PDCCH for the LR-UE is mapped while avoiding the region where the existing PDCCH is mapped (hereinafter sometimes referred to as the "PDCCH region") 40.

[0202] As Figure 10 As shown by the thick arrow in the figure, the PDCCH of the traditional UE is mapped to the existing PDCCH region 40, and the PDSCH of the traditional UE is scheduled in units of 1 subframe using this PDCCH. The PDSCH is scheduled in units of time slots using the PDCCH of the LR-UE. The PDSCH of the same time slot is scheduled using the PDCCH of the LR-UE.

[0203] In Figure 10 In the example shown, the PDCCH of the LR-UE mapped to the 3rd symbol 41 of the first time slot #0 within the subframe is used to schedule the PDSCH of LR-UE#1 and LR-UE#3. The PDCCH of the LR-UE mapped to the 1st symbol 42 of the second time slot #1 within the subframe is used to schedule the PDSCH of LR-UE#1 and LR-UE#2.

[0204] The PDCCH for each time slot mapped to the first time slot within the subframe can be multiplexed with the symbols where the existing PDCCH is mapped for mapping. In this case, for example, the PDCCH for each time slot for the LR-UE and the existing PDCCH for the traditional UE can be mapped to the existing PDCCH region. Thus, there is no need to separately set the PDCCH region for each time slot.

[0205] In addition, in the first time slot within a subframe, there is no need for a per-time-slot PCFICH. The existing PCFICH can be used. Similar to traditional UEs, an LR-UE can identify the number of symbols of the PDCCH and the starting symbol number where the PDSCH is mapped by receiving the existing PCFICH.

[0206] Figure 11 It is a diagram for explaining the mapping method of Embodiment 1. Figure 11 Herein, a method of mapping the PDCCH of each time slot to the existing PDCCH area is described. In Figure 11 In the example shown, the PDCCH of the LR-UE in the first time slot within a subframe, i.e., time slot #0, is mapped to the existing PDCCH area 50. For example, the PDCCH of the LR-UE is mapped to the first symbol 51 of time slot #0. The PDCCH of the LR-UE in time slot #0 is multiplexed with the existing PDCCH and mapped. The PDCCH of the LR-UE in the second time slot within a subframe, i.e., time slot #1, is Figure 10 mapped to the starting symbol 52 of the second time slot, i.e., time slot #1, in the same manner as the example shown.

[0207] In Figure 11 In the example shown, the PDSCHs of LR-UE#1 and LR-UE#3 in the first time slot within a subframe, i.e., time slot #0, are scheduled using the PDCCH of the LR-UE mapped to the existing PDCCH area 50. The PDSCHs of LR-UE#1 and LR-UE#2 in the second time slot within a subframe, i.e., time slot #1, are scheduled using the PDCCH of the LR-UE mapped to the same time slot #1.

[0208] A new DCI with each TTI = 1 time slot can be set as the DCI for LR-UEs. For example, a new DCI format for LR-UEs can be set. Thus, scheduling for each shortened TTI can be performed using the PDCCH.

[0209] In addition, for example, at least one of the information indicating time-slot units and the information determining time slots is set in this DCI. Specifically, scheduling information for per-TTI data can be set in this DCI. As scheduling information, there are allocation information and MCS information, etc. As allocation information, there is information on physical resources in terms of PRBs. For example, the number of PRBs, PRB numbers, etc.

[0210] The eNB schedules PRBs other than the PRB pairs for traditional UEs for use by LR-UEs.

[0211] Map the DCI for the LR-UE to the PDCCH. The CRC scrambled using the C-RNTI (Cell Radio Network Temporary Identifier) of the LR-UE can also be used for the PDCCH for the LR-UE. Thus, similar to the existing PDCCH for UEs, the PDCCH can be detected using the C-RNTI of the LR-UE itself.

[0212] The PDCCH is mapped to the first to fourth symbols at the start of the subframe. The mapping method for mapping the PDCCH to physical resources, such as the method using CCE (Control Channel Element), etc., can be the same as before. By adopting the same method as before, there is no need to re-determine the mapping method for mapping the PDCCH to physical resources, and the PDCCH for traditional UEs and the PDCCH for LR-UEs can coexist. Thus, backward compatibility can be achieved.

[0213] Disclose the operation of the LR-UE. The LR-UE receives at least one of the PCFICH for each time slot and the existing PCFICH, and identifies the number of symbols in the PDCCH region of each time slot and the symbol number at the start of the PDSCH region of each time slot.

[0214] The LR-UE detects the PDCCH region for each time slot or the existing PDCCH region using its own C-RNTI. Thus, the LR-UE can detect the PDCCH sent to itself. The LR-UE obtains the DCI from the PDCCH detected using its own C-RNTI. The LR-UE receives the PDSCH using the scheduling information in the DCI. To identify to which time slot and which PRB the PDSCH is allocated, time slot information and PRB information for each time slot can be used. The LR-UE demodulates the received PDSCH using the scheduling information and obtains the data. The LR-UE can use the CRS as the RS for demodulation.

[0215] If the PDCCH for each time slot of the LR-UE is mapped to the entire system bandwidth, there will be a conflict with the PDSCH of traditional UEs. As Figure 10 and Figure 11 shown, the PDSCH of traditional UEs is mapped in units of 1 subframe. In the first and second time slots of the subframe in Figure 10 , and in the second time slot of the subframe in Figure 11 , symbols 41, 42, and 52 are generated where the PDCCH for each time slot of the LR-UE is mapped to the entire system bandwidth.

[0216] Thus, in the symbols 41, 42, and 52, there will be a conflict between the PDSCH of the legacy UE and the PDCCH per time slot. Due to this conflict, the PDSCH of the legacy UE will be lost in the symbols 41, 42, and 52. As a result, the reception performance of the PDSCH of the legacy UE will deteriorate.

[0217] However, by setting the PDCCH per time slot of the LR-UE to a smaller number of symbols, such as Figure 10 and Figure 11 the 1 symbol shown, the legacy UE can reduce the deterioration of the reception performance of the data through the gain during demodulation such as CRC check.

[0218] In addition, as shown above Figure 11 by using the method of mapping the PDCCH per time slot of the LR-UE to the area 50 where the existing PDCCH is mapped in the first time slot, the impact on the legacy UE can be further reduced. As a result, the deterioration of the reception performance of the data in the legacy UE can be further reduced. Therefore, the legacy UE can receive data.

[0219] In addition, by using the method disclosed in this embodiment, the LR-UE can also receive the PDCCH per time slot and can receive the PDSCH per time slot in the same time slot.

[0220] Therefore, both the legacy UE and the LR-UE can coexist within the same carrier of LTE. As a result, the same method as the existing mapping method can be used, and the control of the mapping method can be unified. Therefore, installation can be easily performed.

[0221] The eNB schedules the PDSCH of the legacy UE in subframe units and schedules the PDSCH of the LR-UE in units corresponding to the TTI. For the PDSCH of the legacy UE, the eNB has performed subframe unit scheduling that includes the second time slot #1 within the subframe before the first time slot #0 within the subframe.

[0222] When the eNB schedules the PDSCH of the LR-UE in the second time slot #1 within the subframe, it uses the physical resources after removing the PRB pairs where the PDSCH of the legacy UE is mapped for scheduling. Assuming that the remaining physical resources after removing the PRB pairs where the PDSCH of the legacy UE is mapped are less than the physical resources required for scheduling the PDSCH of the LR-UE, the PDSCH of the LR-UE that cannot be scheduled can be scheduled using the subsequent TTI, for example, the first time slot #0 within the next subframe. Thus, the eNB can flexibly perform scheduling in units corresponding to the TTI.

[0223] The eNB may perform scheduling considering the PDSCH of the LR-UEs that may be scheduled in the second time slot (i.e., time slot #1) within the subframe in the first time slot (i.e., time slot #0) within the subframe. For example, such scheduling may be performed using the number of connected LR-UEs, the amount of data present in the downlink transmission buffer for the LR-UEs, etc.

[0224] HARQ is disclosed. HARQ is performed in units of TTI. For LR-UEs, it may be performed in units of the shortened TTI, i.e., time slot units in this embodiment. In addition, for conventional UEs, it is performed in units of the existing TTI, i.e., subframe units.

[0225] Since the LR-UEs can be scheduled in units of the shortened TTI using the method disclosed above or the method related to PUCCH disclosed hereinafter, HARQ can be performed in units of the shortened TTI for the downlink. Similarly, since the LR-UEs can be scheduled in units of the shortened TTI using the method disclosed above or the methods related to PHICH and PUSCH disclosed hereinafter, HARQ can be performed in units of the shortened TTI for the uplink.

[0226] In the HARQ of the LR-UEs, the RTT (Round Trip Time) can be shortened. Since scheduling can be performed in units of the shortened TTI, the RTT can be shortened. As a method for shortening the RTT, for example, the time from the transmission timing of downlink data to the reception timing of uplink Ack / Nack in the eNB, or the time from the reception timing of the uplink Ack / Nack to the retransmission timing of downlink data can be shortened. In addition, the time from the scheduling timing of uplink data to the reception timing of the uplink data, or to the transmission of the downlink Ack / Nack corresponding to the reception of the uplink data or the scheduling timing of uplink retransmission data can also be shortened. The case of the eNB is described, but the same applies to the UE.

[0227] In the case of shortening the RTT, the number of TTIs related to the existing RTT can be set to be the same. Since TTIs with a shorter time compared to the existing TTIs are used, even if the number of TTIs is the same, the time of the RTT will be shortened. For example, the number of TTIs from the transmission timing of downlink data to the reception timing of uplink Ack / Nack in the eNB, or the number of TTIs from the reception timing of this uplink Ack / Nack to the retransmission timing of downlink data can be set to be the same as the number of existing TTIs. In addition, the number of TTIs from the scheduling timing of uplink data to the reception timing of uplink data, or to the transmission timing of downlink Ack / Nack corresponding to the reception of this uplink data or the scheduling timing of uplink retransmission data can be set to be the same. Although the case of the eNB is described, the case of the UE is the same.

[0228] By adopting the above structure, retransmission control can be performed at high speed. Thereby, low latency can be achieved and the data transmission speed can be increased.

[0229] In addition, in the HARQ with shortened TTI units, the number of HARQ processes can be increased. For example, when the number of HARQ processes in the existing TTI is 8, the number of HARQ processes when TTI = 1 time slot is set to be twice, i.e., 16. Thereby, even if the time of the RTT is set to be the same, the number of HARQ processes will increase. By increasing the number of HARQ processes and the number of data processes, an attempt is made to increase the data transmission speed.

[0230] As described above, according to this embodiment, the PDSCH of a conventional UE is mapped to physical resources in units of subframes. The PDSCH of the LR-UE is mapped to the area of the physical resources where the PDSCH of the conventional UE is mapped in units of PRBs. Thereby, the PDSCH of the LR-UE can be mapped to physical resources for each TTI. Therefore, the data transmission speed for the LR-UE can be increased. In addition, the PDSCH of the conventional UE and the PDSCH of the LR-UE can coexist in the physical resources within one subframe. Therefore, a communication system that can support various TTIs and has backward compatibility can be realized.

[0231] In addition, in this embodiment, the PDSCH of the conventional UE is mapped to physical resources in units of PRB pairs, and the PDSCH of the LR-UE is mapped to the remaining physical resources other than the PRB pairs where the PDSCH of the conventional UE is mapped. Thereby, the PDSCH of the conventional UE and the PDSCH of the LR-UE can coexist in the physical resources within one subframe more reliably.

[0232] In this embodiment, the PDSCH of a traditional UE is scheduled in units of subframes, and the PDSCH of an LR-UE is scheduled in units corresponding to TTIs. Thus, the PDSCH of a traditional UE and the PDSCH of an LR-UE can coexist more reliably in the physical resources within one subframe.

[0233] Modification Example 1 of Embodiment 1.

[0234] In Embodiment 1, a method of setting the PDCCH for each time slot and mapping it for each time slot is disclosed. As a problem of the PDCCH for each time slot, a situation where a conflict occurs with the PDSCH of a traditional UE in the second time slot is specifically described.

[0235] A situation where the number of symbols of the PDCCH for each time slot is reduced and the degradation of the reception performance of data is reduced by using the gain during demodulation of the PDSCH of a traditional UE is described. However, the degradation of the reception quality and the increase in misreception may be caused by the radio wave propagation environment between the UE and the eNB and the capabilities of the UE, etc. In this modification example, a method for solving this problem is disclosed.

[0236] In Embodiment 1, a situation where the PDCCH for each time slot in the first time slot within a subframe can be reused and mapped to the symbols where the existing PDCCH is mapped is disclosed.

[0237] In this modification example, further, the PDCCH for each time slot in the second time slot within a subframe is reused and mapped to the symbols where the existing PDCCH is mapped.

[0238] The PDCCH for each time slot in the second time slot within a subframe is reused and mapped to the symbols where the existing PDCCH is mapped.

[0239] Thus, there is no need to separately set a PDCCH area for each time slot in the second time slot within a subframe.

[0240] Using the two PDCCHs for each time slot mapped to the existing PDCCH area, the PDSCHs of two time slots within the same subframe are scheduled. For any one LR-UE, two-time-slot scheduling can be performed using the two PDCCHs for each time slot.

[0241] Figure 12 It is a diagram for explaining the mapping method of Modification Example 1 of Embodiment 1. Figure 12 Herein, a method of mapping two PDCCHs for each time slot to the existing PDCCH area is described. In this modification example, the PDCCHs of the LR-UEs in the first and second time slots within a subframe, i.e., time slots #0 and #1, are mapped to the existing PDCCH area 60. The PDCCHs of the LR-UEs are multiplexed and mapped with the existing PDCCH. Figure 12In the example shown, the PDCCHs of each LR-UE that schedule the PDSCHs of LR-UE#1 and LR-UE#3 in the first time slot within the subframe, i.e., time slot #0, and LR-UE#2 in the second time slot within the subframe, i.e., time slot #1, are mapped to the existing PDCCH area 60. Figure 12 In the example shown, the PDSCH of LR-UE#1 is not mapped in the second time slot within the subframe, i.e., time slot #1. The PDSCH is not scheduled in the PRB indicated by reference numeral "61".

[0242] Figure 13 It is a diagram for explaining another example of the mapping method of Modification Example 1 of Embodiment 1. Figure 13 Herein, another example of the method of mapping two PDCCHs per time slot to the existing PDCCH area is described. Figure 13 It shows the case where the PDSCH per time slot of LR-UE#1 is scheduled to the first time slot within the subframe, i.e., time slot #0, and the second time slot, i.e., time slot #1. The PDCCHs of each LR-UE that schedule the PDSCHs of each time slot are mapped to the existing PDCCH area 60. The conventional UE is mapped to the PRB pair 70 composed of PRBs 71 and 72 with different frequency regions between time slots.

[0243] The DCI for the LR-UE is the same as that in Embodiment 1, and can be set as the DCI of one time slot per TTI. The DCI contains the scheduling information of one time slot.

[0244] At least one of the information indicating the time slot unit and the information determining the time slot is set in this DCI. The scheduling information of the data per TTI can be set in this DCI. As the scheduling information, there are allocation information and MCS information, etc. As the allocation information, there is the information of the physical resources in units of PRBs. For example, the number of PRBs, the PRB number, etc. The information associating the TTI number with the time slot number can be set in the scheduling information. Thus, the LR-UE can identify which TTI data is mapped to which time slot.

[0245] The DCI per time slot is mapped to the PDCCH of each time slot, and the scheduling of the first and second time slots within the subframe is performed using the PDCCH of each time slot.

[0246] The existing PDCCH area can be used to perform the scheduling of two time slots within the subframe where the PDCCH area exists for any LR-UE. The scheduling information of each time slot can be different, and the parts other than the time slots can be the same.

[0247] The CRC scrambled with the C-RNTI of the LR-UE can also be used for the PDCCH for the LR-UE. Thus, similar to the existing PDCCH for UEs, the PDCCH can be detected using the C-RNTI of the LR-UE itself.

[0248] The PDCCH is mapped to the first to fourth symbols at the start of the subframe. The mapping method for mapping the PDCCH to physical resources, such as the method using CCE, etc., can be the same as before. By adopting the same method as before, there is no need to re-determine the mapping method for mapping the PDCCH to physical resources, and the PDCCH for traditional UEs and the PDCCH for LR-UEs can coexist. Thus, backward compatibility can be achieved.

[0249] The operation of the LR-UE is disclosed. The LR-UE receives the existing PCFICH and identifies the number of symbols in the existing PDCCH region and the symbol number at the start of the PDSCH region.

[0250] The LR-UE detects the existing PDCCH region using its own C-RNTI. Thus, the LR-UE can detect the PDCCH sent to itself. In the case where the PDCCH for two time slots of the LR-UE is mapped, the LR-UE detects the PDCCH for two time slots using its own C-RNTI. The LR-UE obtains the DCI from the PDCCH detected using its own C-RNTI. The LR-UE receives the PDSCH using the scheduling information in the DCI. To identify to which time slot and which PRB the PDSCH is allocated, the time slot information and the PRB information per time slot can be used. In addition, to identify which TTI's data is mapped to which time slot, the TTI information can be used. The LR-UE demodulates the received PDSCH using the scheduling information and obtains the data.

[0251] HARQ can apply the method disclosed in Embodiment 1. However, in the case of this modification example, the PDCCH including the DCI for the PDSCH in the second time slot, i.e., time slot #1, within the subframe for the LR-UE is mapped to the PDCCH region in the first time slot, i.e., time slot #0, within the subframe. Therefore, for the PDSCH in the second time slot, i.e., time slot #1, within the subframe, the timing for mapping the PDCCH including the DCI for the retransmitted PDSCH is advanced by one time slot. The same applies to the uplink.

[0252] There is no problem when the processing time is sufficient, but problems will occur when the processing time is insufficient. In addition, not only is there a situation where the processing time is insufficient, but there are also cases where retransmission with variable timing is desired for some other reason. As a method for solving the above problems, asynchronous HARQ can be adopted. By not fixing the retransmission timing in advance and using the scheduling of retransmitted data to determine the timing, the retransmission timing can be made variable. Therefore, the retransmission of the PDSCH in the second time slot (i.e., time slot #1) within a subframe can be scheduled using the PDCCH region in the first time slot (i.e., time slot #0) within the subframe. The same applies to the uplink. In addition, this method can also be applied to Embodiment 1.

[0253] By adopting the above structure, retransmission control can be performed at high speed. As a result, low latency can be achieved and the data transmission speed can be increased. In addition, by increasing the number of data processed, an attempt is made to increase the data transmission speed. In addition, by adopting asynchronous HARQ, HARQ can be performed even when the processing time is insufficient and when flexible control of the retransmission timing is desired.

[0254] By using the method disclosed in this modification example, the PDCCH of each time slot for two time slots can be mapped to the existing PDCCH region. Therefore, there is no need for a physical resource region for mapping the PDCCH of each time slot in the first and second time slots.

[0255] Therefore, there will be no conflict between the PDCCH of each time slot and the PDSCH of a traditional UE. Therefore, compared with Embodiment 1, the degradation of the reception quality of data of a traditional UE caused by the conflict can be eliminated.

[0256] In addition, the LR-UE can also receive the shortened TTI, which is the PDCCH of each time slot here, and can receive the PDSCH of each time slot.

[0257] Therefore, an attempt is made to shorten the delay time and increase the data transmission speed.

[0258] In addition, both the traditional UE and the LR-UE can coexist within the same carrier of LTE.

[0259] In addition, the same method as the existing mapping method can be used, and the control of the mapping method can be unified. Therefore, installation can be easily performed.

[0260] Modification Example 2 of Embodiment 1.

[0261] In Modification Example 1 of Embodiment 1, a method for transmitting the PDCCH of each time slot for two time slots using the existing PDCCH region is disclosed.

[0262] In this modification example, other methods of transmitting the PDCCH of the LR-UE by using the existing PDCCH area are disclosed.

[0263] Schedule the PDSCH of the LR-UE in units of 2 time slots by using the PDCCH. Allocate physical resources in units of 2 time slots by using the PDCCH. Schedule data for 2 TTI = 2 time slots by using the PDCCH for the LR-UE.

[0264] For the PDSCH of the LR-UE, one or more PRBs can be used for each time slot. The 2 time slots can both have the same number of PRBs, or each time slot can have a different number of PRBs. Thus, flexible scheduling of data for each shortened TTI can be performed.

[0265] Figure 14 It is a diagram for explaining the scheduling method of Modification Example 2 of Embodiment 1. Figure 14 Herein, a method of scheduling in units of 2 time slots by using the PDCCH of the LR-UE is described. Figure 14 It shows a case where the PDSCH of each time slot of the LR-UE#1 is scheduled to the first time slot and the second time slot within the subframe. The PDCCH of one LR-UE schedules the PDSCH of each time slot. The PDCCH of this LR-UE is mapped to the existing PDCCH area 80.

[0266] A new DCI for 2 TTI = 2 time slots can be newly set as the DCI for the LR-UE. One DCI can include scheduling information for 2 time slots. The scheduling information for each time slot can be different. One DCI can include allocation information for each time slot for 2 time slots.

[0267] This DCI can include information indicating 2 time slots. Alternatively, the DCI format including scheduling information for 2 time slots can be set as a new DCI format. Thus, the LR-UE can recognize the case including scheduling information for 2 time slots.

[0268] This DCI can include scheduling information for each TTI data for 2 TTI. As the scheduling information, there are allocation information, MCS information, etc. As the allocation information, there is information on physical resources in units of PRBs. For example, the number of PRBs, the PRB number, etc.

[0269] Information for determining which time slot it is can be provided in the DCI. In addition, information associating the TTI number with the time slot number can be set. Thus, the LR-UE can recognize which TTI data is mapped to which time slot.

[0270] In the case where there is no data for 2 time slots, it can be set to no scheduling or no transmission.

[0271] As another method, an existing scheduling method for PRB pairs can also be applied. The PRB pair is determined by the scheduling information for one subframe portion. One subframe is two time slots. Therefore, by using the scheduling method for PRB pairs, scheduling for two time slot portions can be performed. Therefore, it can be completed without using a new method, thereby avoiding complication of the communication system.

[0272] The eNB schedules PRBs other than the PRB pairs for traditional UEs for use by LR-UEs.

[0273] Figure 15 It is a diagram for explaining the scheduling method of Modification Example 2 of Embodiment 1. Figure 15 Herein, a method is described in which the existing scheduling method for PRB pairs is applied to the PDCCH of an LR-UE to perform scheduling in units of two time slots.

[0274] In Figure 15 In the example shown, using the method of PRB pairs, the PDSCH of LR-UE#1 in the first time slot and the second time slot within a subframe is scheduled using the PDCCH of one LR-UE. Similarly for the PDSCH of LR-UE#2 in the first time slot and the second time slot within the subframe, using the method of PRB pairs, the scheduling is performed using the PDCCH of one LR-UE.

[0275] In Figure 15 In the example shown, LR-UE#1 is mapped to PRB pair 95 composed of PRB91 in time slot #0 and PRB94 in time slot #1. In PRB pair 96 composed of PRB93 in time slot #0 and PRB92 in time slot #1, LR-UE#2 is mapped to PRB93 in time slot #0 and LR-UE#2 is mapped to PRB92 in time slot #1.

[0276] In Figure 14 and Figure 15 In the example shown, traditional UEs are not described, but the PDSCH of traditional UEs may also be mapped. In this case, the scheduling of this PDSCH is performed using the PDCCH of the traditional UE. The PDCCH of the traditional UE is multiplexed with the PDCCH of the LR-UE and mapped to the existing PDCCH regions 80, 90. Hereinafter, for traditional UEs, the description will be omitted unless otherwise specified.

[0277] In this modification example, the DCI for the LR-UE is mapped to the PDCCH. It is also possible to use the CRC scrambled with the C-RNTI of the LR-UE for the PDCCH for the LR-UE. Thus, similar to the existing PDCCH for UEs, the PDCCH can be detected using the C-RNTI of the LR-UE itself.

[0278] The PDCCH is mapped to the first to the fourth symbols at the start of a subframe. The mapping method for mapping the PDCCH to physical resources, such as the method using CCE, etc., can be the same as in the past. By adopting the same method as in the past, there is no need to re-determine the mapping method for mapping the PDCCH to physical resources, and it is possible to have a hybrid of the PDCCH for traditional UEs and the PDCCH for LR-UEs. Thus, backward compatibility can be achieved.

[0279] The operation of the LR-UE is disclosed. The LR-UE receives the PCFICH and identifies the symbol at the start of the PDSCH region. The LR-UE detects the PDCCH region using its own C-RNTI. Thus, the LR-UE can detect the PDCCH sent to itself. The LR-UE obtains the DCI from the PDCCH detected using its own C-RNTI. The LR-UE receives the PDSCH using the scheduling information in the DCI. When there is scheduling information for two time slots in the DCI, the PDSCH for two time slots is received. In order to identify to which time slot and which PRB the PDSCH is allocated, the time slot information and the PRB information per time slot can be used. In addition, in order to identify to which time slot the data of which TTI is mapped, the TTI information can be used. The LR-UE demodulates the received PDSCH using the scheduling information and obtains the data.

[0280] HARQ can apply the method disclosed in Modification Example 1 of Embodiment 1. Thus, the same effects as those of Modification Example 1 of Embodiment 1 can also be obtained. As another method, HARQ can also be performed in units of 2 TTIs. In this case, both traditional UEs and LR-UEs perform HARQ in units of one subframe, so the complication of the scheduler can be avoided.

[0281] By using the method disclosed in this modification example, the same effects as those of Modification Example 1 of Embodiment 1 can be obtained.

[0282] In addition, since two time slots' worth of scheduling information is included in one DCI, the number of PDCCHs of the LR-UE mapped to the PDCCH region can be reduced. Therefore, the utilization efficiency of physical resources in the mapping of the PDCCH can be improved.

[0283] In addition, the LR-UE detects and receives one PDCCH from the existing PDCCH region, so it can receive two time slots' worth of scheduling information. Thus, the PDCCH reception time of the LR-UE can be shortened and the reception power can be reduced.

[0284] Embodiment 1 Modification Example 3.

[0285] In Variant 1 of Embodiment 1, a method of transmitting the PDCCH of each time slot for 2 time slots using an existing PDCCH area is disclosed. In this variant, another method of transmitting the PDCCH of an LR-UE using an existing PDCCH area is disclosed.

[0286] The eNB transmits the PDCCH of each time slot including the DCI of the previous time slot and the PDCCH of each time slot including the DCI of the same time slot as the PDCCH area using an existing PDCCH area.

[0287] The eNB determines the scheduling of the PDSCH for the odd-numbered time slots, i.e., time slot #odd, includes this scheduling information in the DCI, and maps this DCI to the PDCCH of each time slot. The eNB maps the PDCCH of each time slot to the PDCCH area of the next time slot and transmits it. The eNB determines the scheduling of the PDSCH for the even-numbered time slots, i.e., time slot #even, includes this scheduling information in the DCI, and maps this DCI to the PDCCH of each time slot. The eNB maps the PDCCH of each time slot to the PDCCH area of the same time slot and transmits it.

[0288] The PDCCH of each time slot of the second time slot within a subframe is multiplexed with the symbols mapped with the existing PDCCH of the next subframe and mapped. The PDCCH of each time slot of the first time slot within a subframe is multiplexed with the symbols mapped with the existing PDCCH of the same subframe and mapped.

[0289] The scheduling of the PDSCH of the previous time slot and the PDSCH of the same time slot is performed using the PDCCH of two time slots mapped to an existing PDCCH area. For any one LR-UE, the scheduling of 2 time slots of the previous time slot and the same time slot can be performed using the PDCCH of two time slots.

[0290] This is different from Variant 1 of Embodiment 1 above in that the scheduling of the PDSCH of the previous time slot is performed using the PDCCH of each time slot mapped to an existing PDCCH area.

[0291] Figure 16 This is a diagram for explaining the scheduling method of Variant 3 of Embodiment 1. Figure 16 Herein, a method of performing the scheduling of the previous time slot and the same time slot using the PDCCH of an LR-UE mapped to an existing PDCCH area is described.

[0292] In this modification example, the PDCCH that schedules the PDSCH of the LR-UE in the first time slot within a subframe is mapped to the same existing PDCCH area as the PDCCH that schedules the PDSCH of the LR-UE in the second time slot of the previous subframe. The PDCCH of the LR-UE is multiplexed with the existing PDCCH and mapped.

[0293] In Figure 16 In the example shown, the PDCCH that schedules the PDSCH of LR-UE#1 and LR-UE#3 in the first time slot, i.e., time slot #0, of subframe #2 is mapped to the existing PDCCH area 102 of subframe #2 together with the PDCCH that schedules the PDSCH of LR-UE#1 and LR-UE#2 in the second time slot, i.e., time slot #1, of subframe #1.

[0294] In subframe #2, the legacy UE is mapped to a PRB pair 105 composed of two PRBs 103 and 104 with different frequency bands. The PDCCH of the legacy UE mapped to the existing PDCCH area 102 of subframe #2 is used for scheduling the PDSCH of the legacy UE mapped to the PRB pair 105.

[0295] The PDCCH that schedules the PDSCH of LR-UE#1 and LR-UE#3 in the first time slot, i.e., time slot #0, of subframe #1 is mapped to the existing PDCCH area 101 of subframe #1.

[0296] The DCI for the LR-UE is the same as that in Embodiment 1 and can be set as the DCI for each TTI, here for each time slot. The DCI contains scheduling information for one time slot.

[0297] At least one of the information indicating the time slot unit and the information for determining the time slot is set in the DCI. The information for determining the subframe can be set in the DCI. The scheduling information for each TTI data can also be set in the DCI. As the scheduling information, there are allocation information and MCS information, etc. As the allocation information, there is information on the physical resources in units of PRBs. For example, the number of PRBs, the PRB number, etc. The information associating the TTI number with the time slot number, or the information associating the TTI number, subframe number, and time slot number can be set in the scheduling information. Thus, the LR-UE can identify which TTI data is mapped to which time slot.

[0298] The DCI for each time slot is respectively mapped to the PDCCH for each time slot, and the scheduling of the previous time slot and the same time slot of the subframe with the existing PDCCH mapped is performed using the PDCCH for each time slot.

[0299] It is possible to use the existing PDCCH region to schedule the previous time slot and the same time slot of the subframe in which the PDCCH region exists for any LR-UE. The scheduling information for each time slot can be different, and the parts other than the time slots can be the same.

[0300] It is also possible to use the CRC scrambled with the C-RNTI of the LR-UE for the PDCCH for the LR-UE. Similar to the existing PDCCH for UEs, it is possible to detect the PDCCH using the C-RNTI of the LR-UE itself.

[0301] The PDCCH is mapped to the first symbol to the fourth symbol at the start of the subframe. The mapping method for mapping the PDCCH to the physical resources, such as the method using CCE, etc., can be the same as before. By adopting the same method as before, there is no need to re-determine the mapping method for mapping the PDCCH to the physical resources, and it is possible to have the PDCCH for traditional UEs and the PDCCH for LR-UEs coexist. Thus, backward compatibility can be achieved.

[0302] The operation of the LR-UE is disclosed. The LR-UE receives the existing PCFICH and identifies the number of symbols in the existing PDCCH region and the symbol number at the start of the PDSCH region.

[0303] The LR-UE detects the existing PDCCH region using its own C-RNTI. Thus, the LR-UE can detect the PDCCH sent to itself. In the case where the PDCCH for two time slots of the LR-UE is mapped, the LR-UE detects the PDCCH for two time slots using its own C-RNTI. The LR-UE obtains the DCI from the PDCCH detected using its own C-RNTI. The LR-UE receives the PDSCH using the scheduling information in the DCI. In order to identify to which time slot and which PRB the PDSCH is allocated, the time slot information and the PRB information for each time slot can be used. In addition, in order to identify which TTI's data is mapped to which time slot, the TTI information can be used. The LR-UE demodulates the received PDSCH using the scheduling information and obtains the data.

[0304] In this modified example, the LR-UE receives the PDSCH of the previous time slot or the PDSCH of the same time slot using the scheduling information in the DCI of the detected PDCCH.

[0305] The LR-UE pre-receives and stores the time slots with odd numbers of time slots, i.e., the second time slot within a subframe. At the moment when the LR-UE receives the second time slot within a subframe, it cannot identify whether the PDSCH sent to itself is scheduled. By receiving and detecting the existing PDCCH region of the next time slot, it can be determined whether there is a PDSCH sent to itself. Therefore, by receiving and storing the second time slot within a subframe as described above, the LR-UE can receive the PDSCH of the time slot before the time slot when the scheduling information is received.

[0306] In the method disclosed in Variant 1 of Embodiment 1 or Variant 2 of Embodiment 1, for example, when data is generated during the first time slot within a subframe, the eNB cannot schedule to the next time slot of this time slot, specifically, the second time slot within the subframe. This is because the scheduling information of this time slot has been sent in the existing PDCCH region of the first time slot within the subframe. In the above case, the eNB needs to further wait for the subsequent time slot, specifically, wait for 1 time slot until the first time slot of the next subframe, to send the scheduling information and the data. That is, depending on the generation timing of the data, a delay of 1 time slot may occur.

[0307] However, by using the method disclosed in this variant, even when data is generated during the first time slot within a subframe, the eNB can schedule to the next time slot of this time slot, specifically, the second time slot within the subframe. This is because the scheduling information of this time slot has been sent in the existing PDCCH region of the first time slot within the next subframe. For example, when data is generated during the first time slot within a subframe, the eNB uses the second time slot within the subframe to schedule the data and maps the data to the second time slot within the subframe. Then, the eNB sends the scheduling information of the data sent using the first time slot within the next subframe.

[0308] Therefore, according to the method disclosed in this variant, data can be sent in time slot units immediately after the data is generated. Thus, a delay of 1 time slot can be prevented from occurring.

[0309] HARQ can apply the method disclosed in Variant 1 of Embodiment 1. Thus, the same effect as that of Variant 1 of Embodiment 1 can also be obtained.

[0310] By using the method disclosed in this variant, the PDCCH of each time slot for 2 time slots can be mapped to the existing PDCCH region. Therefore, there is no need for a physical resource region for mapping the PDCCH of each time slot in the first and second time slots.

[0311] Therefore, there will be no conflict between the PDCCH of each time slot and the PDSCH of the traditional UE. Therefore, compared with the above-described Embodiment 1, the degradation of the reception quality of the data of the traditional UE caused by this conflict can be eliminated.

[0312] In addition, the LR-UE can also receive the shortened TTI, here the PDCCH of each time slot, and can receive the PDSCH of each time slot.

[0313] Therefore, it is possible to shorten the delay time and increase the data transmission speed.

[0314] In addition, both the traditional UE and the LR-UE can coexist within the same carrier of LTE.

[0315] In addition, the same method as the existing mapping method can be used, and the control of the mapping method can be unified. Therefore, installation can be easily performed.

[0316] In addition, in Modification 1 of Embodiment 1 and Modification 2 of Embodiment 1, a 1-slot delay occurs depending on the generation timing of the data. However, by using the method disclosed in this modification, the 1-slot delay can be prevented from occurring. Therefore, it is possible to shorten the delay time and increase the data transmission speed.

[0317] The method using PRB pairs disclosed in Modification 2 of Embodiment 1 can also be applied. Thereby, the amount of PDCCH can be reduced. In addition, the usage efficiency of the physical resources in the mapping of the PDCCH can be increased.

[0318] In addition, the LR-UE detects one PDCCH from the existing PDCCH area and receives it, thereby being able to receive scheduling information for 2 time slots. Thereby, the PDCCH reception time of the LR-UE can be shortened and the reception power can be reduced.

[0319] In addition, by applying the existing method of PRB pairs, scheduling can be performed using a method unified with the traditional UE, and the control can be made easier.

[0320] Embodiment 1 Modification 4.

[0321] In the existing LTE standard, the mapping of the PDSCH of the traditional UE to the physical resources is performed using PRB pairs. The mapping methods are localized and distributed. The localized method is to map the PRBs of the PRB pair to the same frequency region, that is, the same subcarriers, and the distributed method is to map them to different frequency regions, that is, different subcarriers.

[0322] However, when mapping the data of the shortened TTI for the LR-UE to physical resources on a per time slot basis, the data is per time slot, so it is impossible to perform distributed mapping. In addition, frequency diversity gain cannot be obtained.

[0323] The following discloses a method for solving the above problems. In the mapping of the PDSCH for the LR-UE to physical resources, it is mapped to a discontinuous frequency region, i.e., discontinuous subcarriers, within one time slot. As the frequency region, the PRB unit can be adopted. Distributed mapping is performed within one time slot.

[0324] The case of allocating one or more PRBs to the LR-UE within one time slot is disclosed. As the multiple PRBs, they can be consecutive PRBs or discontinuous PRBs. When the radio wave environment is good in a specific frequency region, by using consecutive PRBs (localized) in this frequency region, the communication quality can be improved. In addition, in the case of frequency attenuation, by using discontinuous PRBs (distributed), even if the radio wave environment in a specific frequency region is poor, the desired communication quality can be obtained.

[0325] Multiple discontinuous PRBs can be set as a PRB set. As a scheduling method for the PRB set, PRB set information can be newly set in the DCI.

[0326] As an allocation method for the PRB set, there is a method of determining the multiple PRBs using absolute PRB numbers. In this case, the absolute PRB numbers of each PRB in the PRB set can be included as allocation information.

[0327] As allocation information, the smallest PRB number and frequency interval information up to the next consecutive PRB, such as the number of subcarriers, or PRB interval information, such as the number of PRBs, can be included. Using the smallest PRB number in the PRB set and the frequency interval or PRB interval up to the next consecutive PRB, the multiple PRBs can be determined.

[0328] In addition, the allocation information can include the number information of the PRBs and can also include information indicating the last PRB. For the last PRB, the frequency interval information or PRB interval information up to the next consecutive PRB can be not set. Thereby, it is recognized as the last PRB.

[0329] Figure 17 It is a diagram for explaining the scheduling method of Modification Example 4 of Embodiment 1. Figure 17 Herein, a method for scheduling multiple PRBs for the LR-UE within one time slot is described. In this modification example, the multiple PRBs are mapped to the PDSCH of the LR-UE. The multiple PRBs are allocated to this PDSCH using the PDCCH of the LR-UE.

[0330] In Figure 17 In the example shown in Figure 17 , in the first time slot within the subframe, the PDSCH of LR-UE#1 is mapped to two non-consecutive PRBs. The scheduling of this PDSCH is performed using the PDCCH of LR-UE#1. This PDCCH is mapped to the existing PDCCH area 110.

[0331] In the second time slot within the subframe, the PDSCH of LR-UE#2 is mapped to two consecutive PRBs. The scheduling of this PDSCH is performed using the PDCCH of LR-UE#2. This PDCCH is mapped to the existing PDCCH area 110.

[0332] The allocation information may include the first and last PRB number information of the PRBs. When the intervals of the respective PRBs are the same frequency interval, by further including the number information of the PRBs, the frequency interval information between the PRBs, such as the number of subcarriers, or the PRB interval information, such as the number of PRBs, the plurality of PRBs can be determined.

[0333] In the case where there are two PRBs, as a pair of PRBs within one time slot, the existing allocation method of the pair of PRBs can also be applied.

[0334] Information for determining whether it is a pair of PRBs within one time slot for an LR-UE or a pair of PRBs between two time slots for a legacy UE can be set. This information can be included in the scheduling information.

[0335] Alternatively, information for determining whether it is for an LR-UE or a legacy UE can be set. It can be set such that in the case of an LR-UE, a pair of PRBs within the same time slot is used, and in the case of a legacy UE, a pair of PRBs between two time slots is used. By adopting the above method, the same method for designating a pair of PRBs as in the past can be applied, and thus control complexity can be avoided.

[0336] As another method, the eNB sets the information of the existing pair of PRBs between two time slots in the PRB pair information of the DCI of the PDCCH of the legacy UE, and sets the information of the pair of PRBs within one time slot in the PRB pair information included in the DCI of the PDCCH of the LR-UE. In addition, the PDCCH including the DCI determines whether it is for an LR-UE or a legacy UE, and this DCI includes the PRB pair information. Thus, the legacy UE or the LR-UE can determine whether the PRB pair of the PDCCH is a pair of PRBs between two time slots or a pair of PRBs within one time slot based on whether it is a legacy UE or an LR-UE. As a result, it is possible to do without explicit information indicating which pair of PRBs it is.

[0337] Embodiment 1 Variant 5.

[0338] Embodiment 1 discloses a method of setting PDCCH per time slot and mapping it per time slot. Embodiment 1 elaborates that since PDCCH is set in the symbols within a time slot across the entire system bandwidth, there is a problem of inevitable conflict with the PDSCH of traditional UEs.

[0339] It is elaborated that the number of symbols of PDCCH per time slot is reduced, and the impact on the PDSCH of traditional UEs is reduced. The gain during demodulation is used to reduce the degradation of data reception performance. However, the reception quality degradation and the increase in misreception may be caused by the radio wave propagation environment between the UE and the eNB and the capabilities of the UE, etc. In this modified example, a method for solving this problem is disclosed.

[0340] Map the PDCCH per time slot to one or more PRBs within the time slot. Use the PDCCH per time slot to schedule data for each TTI. Use the PDCCH per time slot for scheduling in time slot units. Use the PDCCH per time slot to allocate physical resources in time slot units. Schedule the PDSCH in the same time slot as the PDCCH allocated to each time slot.

[0341] Thus, the physical resource region for mapping the PDCCH per time slot can be set only to a predetermined PRB, that is, a predetermined frequency region, rather than the entire system bandwidth.

[0342] Therefore, scheduling can be performed in a manner that does not conflict with the PDSCH of traditional UEs.

[0343] In addition, even when the PDCCH per time slot increases due to the increase in LR-UEs and the number of symbols required for PDCCH increases, since there is no conflict with the PDSCH of traditional UEs, degradation of the communication quality of data caused by this conflict can also be prevented.

[0344] The PDCCH region for LR-UEs can be set per time slot. As the region for mapping the PDCCH to physical resources, it can be set in PRB units. One or more PRBs can be used. The PDCCH per time slot can be set as LR-EPDCCH. Use LR-EPDCCH as the PDCCH for LR-UEs.

[0345] Map the LR-EPDCCH to the physical resource region where the existing PDSCH is mapped.

[0346] The PDSCH of LR-UEs avoids mapping to the PRB pairs where the PDSCH of traditional UEs is mapped.

[0347] The LR-EPDCCH in even-numbered time slots maps while excluding the symbols (symbols 1 to 4) where the existing PDCCH is mapped.

[0348] Figure 18 This is a diagram for explaining the scheduling method of Variant 5 of Embodiment 1. Figure 18 Herein, a method for scheduling LR-UEs using LR-EPDCCH is described. As Figure 18 shown, LR-EPDCCH is mapped to the physical resource region where the existing PDSCH is mapped per time slot. For example, LR-EPDCCH#1 is mapped to the first time slot within a subframe, and LR-EPDCCH#2 is mapped to the second time slot within a subframe.

[0349] LR-EPDCCH#1 is the PDCCH of LR-UE#1 and schedules the PDSCH of LR-UE#1 in the same time slot. LR-EPDCCH#2 is the PDCCH of LR-UE#2 and schedules the PDSCH of LR-UE#2 in the same time slot. LR-EPDCCH#1 in the first time slot within a subframe is mapped to symbols other than the existing PDCCH region 111.

[0350] There is disclosed a method of setting a region (hereinafter sometimes referred to as "LR-EPDCCH region") for mapping the PDCCH of LR-UEs using PRBs predetermined per time slot. Herein, a method of mapping the PDCCH of LR-UEs to this region is further disclosed.

[0351] In the past, as a control channel mapped to a predetermined frequency region, there was EPDCCH. However, EPDCCH is mapped to an entire subframe. Therefore, when applying the mapping method of the existing EPDCCH to the mapping method of the PDCCH per time slot, it can be mapped to a predetermined frequency region, but cannot be mapped per time slot.

[0352] Herein, a method of mapping the PDCCH of LR-UEs using PRBs predetermined per time slot is disclosed.

[0353] DCI in units of one time slot is mapped to LR-EPDCCH. DCI in units of one time slot is divided into one or more control channel units, which are LR-ECCEs here.

[0354] As the physical resource of LR-EPDCCH, LR-EREG composed of one or more REs (Resource Element) is set. LR-ECCE is mapped to LR-EREG.

[0355] Thus, DCI in units of one time slot is mapped to LR-EPDCCH, and LR-EPDCCH is mapped to the physical resources within one time slot.

[0356] Any number of LR-EREGs can be formed within a PRB. For example, 16 sets of LR-EREG = 0 to 15 can be formed within a PRB. In this case, the existing EREG structure for EPDCCH can be utilized (refer to Non-Patent Document 11). However, the existing EPDCCH forms 16 sets of EREGs within a PRB pair. However, since the LR-EPDCCH cannot obtain a PRB pair, the EREG structure cannot be directly applied.

[0357] Therefore, while maintaining the configuration of EREGs within a PRB pair, only the EREGs within a PRB are used as LR-EREGs. Thus, LR-EREGs can be formed within a PRB while keeping the number of sets of EREGs and LR-EREGs the same.

[0358] For example, when forming 16 sets of LR-EREGs within 1 PRB, the number of REs contained in 1 LR-EREG within 1 PRB is 4 or 5.

[0359] The number of LR-EREGs can be configured into 16 sets in the same way as the existing EREGs, but the number of REs in each LR-EREG is halved.

[0360] For the number of REs required for mapping DCI, both EPDCCH and LR-EPDCCH are the same. Therefore, if the number of REs in LR-EREG is halved, there will be a problem that DCI cannot be accommodated. A method to solve the above problem is disclosed below.

[0361] Increase the number of LR-EPDCCH sets allocated to the LR-UE. Generally, the eNB allocates an EPDCCH region to the UE. This region can be continuous or non-continuous. Sometimes this EPDCCH region is referred to as an "EPDCCH set". In the past, 2 EPDCCH sets could be allocated to the UE.

[0362] Similarly, the LR-EPDCCH region allocated by the eNB to the LR-UE is set as an LR-EPDCCH set. Increase the maximum number of LR-EPDCCH sets that can be allocated to this LR-UE to be greater than 2.

[0363] The UE searches for LR-EPDCCH sets with a number greater than 2 and receives its own LR-EPDCCH.

[0364] For example, for 1 LR-UE, in addition to 1 and 2, 4 sets can also be set as the number of LR-EPDCCH sets.

[0365] Thus, the number of PRBs included in all LR-EPDCCH sets can be increased. In addition, the number of PRBs received by the LR-UE can also be increased. Therefore, even if the number of REs in the LR-EREG within 1 PRB is halved, since the number of PRBs is increased, the same number of REs as before can be ensured.

[0366] Other methods are disclosed below. Increase the LR-EPDCCH area allocated by the eNB to the LR-UE. Increase the number of PRBs constituting the LR-EPDCCH set allocated to the LR-UE. Increase the maximum number of PRBs that can be allocated to form the LR-EPDCCH set for the LR-UE to be greater than 8. The UE searches for the LR-EPDCCH set composed of PRBs with a number larger than 8 and receives its own LR-EPDCCH.

[0367] For example, for one LR-UE, in addition to 2, 4, and 8, 16 can also be set as the number of PRBs constituting the LR-EPDCCH set.

[0368] Thus, the number of PRBs included in all LR-EPDCCH sets that can be allocated to the LR-UE can be increased. In addition, the number of PRBs received by the LR-UE can also be increased. Therefore, even if the number of REs in the LR-EREG within 1 PRB is halved, since the number of PRBs is increased, the same number of REs as before can be ensured.

[0369] Other methods are disclosed below. The aggregation level of the control channel element (CCE) supported by the LR-UE is also reduced compared to the previous quantity. Previously, as the aggregation level of CCEs for one UE, 1, 2, 4, 8, 16, and 32 could be set. Here, the maximum aggregation level of CCEs supported by the LR-UE is less than 32. For example, the maximum number of CCEs supported by the LR-UE is set to 16.

[0370] Thus, the number of CCEs containing the DCI for the LR-UE can be reduced. Thus, the number of REs required for mapping the DCI for the LR-UE can be reduced.

[0371] Therefore, even if the number of REs in the LR-EREG within 1 PRB that can be allocated to the LR-UE is halved and the number of REs included in all LR-EPDCCH sets is halved, the DCI for the LR-UE can still be mapped.

[0372] Other methods are disclosed below. Reduce the physical resource amount required for the LR-ECCE containing the DCI for the LR-UE. In order to reduce the physical resource amount, the amount of information of the DCI for the LR-UE can be reduced.

[0373] For example, in the past, for the ECCE mapped to the EPDCCH, 1 ECCE was mapped to 36 REs or 72 REs. Here, the physical resources required for the LR-ECCE containing the DCI for the LR-UE are reduced to less than 36 REs or 72 REs. For example, the physical resources of 1 LR-ECCE are set to 18 REs or 36 REs.

[0374] Thereby, the amount of physical resources required for the LR-ECCE containing the DCI for the LR-UE can be reduced.

[0375] Therefore, even if the number of REs in the LR-EREG within 1 PRB that can be allocated to the LR-UE is halved and the number of REs in all LR-EPDCCH sets is halved, the DCI for the LR-UE can be mapped.

[0376] In this modification example, as described above, the case of forming an arbitrary number of LR-EREGs within a PRB is disclosed. As an example, the case of forming 16 groups of LR-EREG = 0 to 15 within a PRB is disclosed. As another example, 8 groups of LR-EREG = 0 to 7 are formed within a PRB. The numbering of the LR-EREGs can be the same in all PRBs for the LR-EPDCCH. Or, two numberings of the LR-EREGs can be set. For example, it can be divided into PRBs with LR-EREG = 0 to 7 and PRBs with LR-EREG = 8 to 15 for use.

[0377] In the case of forming 8 groups of LR-EREGs within 1 PRB, the number of REs contained in 1 LR-EREG within 1 PRB is 9. Thereby, the number of REs per LR-EREG can be set to the same value as the number of REs per existing EREG.

[0378] As described above, for the number of REs required to map the DCI, both the EPDCCH and the LR-EPDCCH are the same.

[0379] Therefore, by using the method disclosed here, the number of REs required for the LR-EPDCCH area allocated to one LR-UE can be obtained. The DCI for the LR-UE can be accommodated. There is no need for countermeasures for the reduction in the number of REs.

[0380] In the method disclosed here, the number of REs per LR-EREG can be made the same as the number of REs per existing EREG, but the number of LR-EREGs becomes half of the number of existing EREGs. In this case, since the number of LR-EREGs constituting the LR-EPDCCH area is reduced, the number of LR-UEs that can be supported by the LR-EPDCCH area is also reduced.

[0381] As a method for solving the above problems, the above-described solution method for halving the number of REs in LR-EREG can be applied.

[0382] For the DCI for LR-UE, the method disclosed in Embodiment 1 can be applied.

[0383] Map the DCI for LR-UE to LR-EPDCCH.

[0384] The CRC scrambled with the C-RNTI of the LR-UE can also be used for the LR-EPDCCH for LR-UE. Similar to the existing PDCCH for UE, the LR-EPDCCH can be detected using the C-RNTI of the LR-UE itself.

[0385] Disclose a method for setting LR-EPDCCH.

[0386] Set the LR-EPDCCH area. It is also possible to set it as an LR-EPDCCH set. The resources on the frequency axis of the LR-EPDCCH set are set in units of PRB. Continuous PRBs can be set, or discontinuous PRBs can be set.

[0387] The resources on the time axis of the LR-EPDCCH are set in units of shortened TTI instants. Continuous instants can be set, or discontinuous instants can be set.

[0388] Use one instant to set the LR-EPDCCH area or the LR-EPDCCH set.

[0389] The LR-EPDCCH can be set for each cell or for each LR-UE. Alternatively, each cell and each LR-UE can be combined.

[0390] For example, the setting on the time axis of the LR-EPDCCH is per cell, and the setting on the frequency axis is per UE. Thus, the eNB can preset the instant timing of the LR-EPDCCH, and scheduling becomes easy. The LR-UE can recognize the instant timing of the LR-EPDCCH set for each cell and can recognize the PRB structure of the LR-EPDCCH set for each UE in that instant.

[0391] As another example, the setting of the resources for which the LR-EPDCCH can be set is performed per cell. In fact, the setting of the LR-EPDCCH for the LR-UE can also be performed per UE. By presetting the setting of the resources for which the LR-EPDCCH can be set per cell, the scheduling of the LR-EPDCCH to the same subframe as the conventional UE becomes easy. In addition, the coexistence of the conventional UE and the LR-UE becomes easy.

[0392] The setting of the LR-EPDCCH can be determined statically, or can be determined quasi-statically or dynamically.

[0393] In the case of static determination, it can be determined according to standards, etc. In the case of quasi-static or dynamic determination, RRC signaling can be used.

[0394] For example, the setting for each cell is determined in advance using standards, and the setting for each UE can be determined quasi-statically or dynamically using RRC signaling.

[0395] As another example, in the case of the setting for each cell, as broadcast information, it can be broadcast by the eNB to the UEs within the coverage area. In the case of the setting for each LR-UE, using UE-specific signaling, the eNB notifies the LR-UE that performs the shortened TTI.

[0396] The eNB can include the setting information of the LR-EPDCCH in the RRC connection reconfiguration (RRC Connection Reconfiguration) message and notify it to the LR-UE as RRC signaling.

[0397] In the case where the number of symbols of the PDCCH becomes larger, etc., the number of LR-EREGs for LR-ECCE in the even-numbered slots of the time slot becomes smaller. As a method for solving this problem, in the method of increasing the number of LR-EPDCCH sets allocated to the LR-UE described above, the number of LR-EPDCCH sets can be further increased. Or, in the method of the eNB increasing the LR-EPDCCH area allocated to the LR-UE described above, the LR-EPDCCH area can be further increased. Thereby, even if the number of symbols of the PDCCH becomes larger, the number of REs in the LR-EPDCCH area of the even-numbered slots of the time slot can be increased, and DCI for the LR-UE can be mapped for each time slot.

[0398] The actions of the LR-UE are disclosed. The LR-UE receives the PCFICH and identifies the symbol at the start of the PDSCH area in time slot #0. The LR-UE detects the LR-EPDCCH area using its own C-RNTI. The structure of the LR-EPDCCH area is notified by the eNB using RRC signaling, for example.

[0399] Thus, the LR-UE can detect the LR-EPDCCH sent to itself. The LR-UE obtains DCI from the LR-EPDCCH detected by its own C-RNTI. The LR-UE receives the PDSCH using the scheduling information in the DCI. In order to identify to which time slot and which PRB the PDSCH is allocated, the time slot information and the PRB information per time slot can be used. The LR-UE demodulates the received PDSCH using the scheduling information and obtains the data. The LR-UE can use the CRS as the RS for demodulation. Alternatively, the RS for each UE can be set separately and used.

[0400] HARQ can apply the method disclosed in Variant 1 of Embodiment 1. Thus, the same effect as Variant 1 of Embodiment 1 can be obtained.

[0401] Variant 6 of Embodiment 1.

[0402] It is also possible to combine the above method of using the existing PDCCH area to send the PDCCH per time slot for the LR-UE and the method of using the predetermined PRB (LR-EPDCCH) per time slot to send the PDCCH per time slot for the LR-UE.

[0403] Figure 19 It is a diagram for explaining the transmission method of Variant 6 of Embodiment 1. Figure 19 It shows an example of the method of combining the method of using the existing PDCCH area to send the PDCCH per time slot to the LR-UE and the method of using the LR-EPDCCH to send the PDCCH per time slot to the LR-UE. The PDCCH per time slot in the first time slot within the subframe is sent using the LR-EPDCCH, and the PDCCH per time slot in the second time slot within the subframe is sent using the existing PDCCH area 112.

[0404] The PDSCH in the same time slot is scheduled using the PDCCH per time slot mapped to the LR-EPDCCH area in the first time slot within the subframe. In addition, the PDSCH in the next time slot is scheduled using the PDCCH per time slot mapped to the existing PDCCH area in the first time slot within the subframe.

[0405] Since the PDCCH per time slot in the second time slot within the subframe is sent using the existing PDCCH area, the method of including 1 data portion of 1 TTI, here 1 time slot portion of DCI, in the PDCCH per time slot can be used. Variant 1 of the above Embodiment 1 can be applied to the method including 1 time slot portion of DCI.

[0406] There is already an existing PDCCH region in the first time slot within a subframe. Therefore, by using this PDCCH region, there is no need to configure an LR-EPDCCH region in the time slots of both sides within one subframe. As a result, an increase in the resources of the new control channel can be suppressed, and thus a reduction in the resources of the data channel can be suppressed. Therefore, the throughput of the system can be improved.

[0407] Figure 20 It is a diagram for explaining the transmission method of Modification Example 6 of Embodiment 1. Figure 20 It shows another example of a method that combines the following two methods, namely: a method of transmitting the PDCCH of each time slot to an LR-UE by using an existing PDCCH region and a method of transmitting the PDCCH of each time slot to an LR-UE by using an LR-EPDCCH.

[0408] The PDCCH of each time slot in the first time slot within a subframe is transmitted by using the existing PDCCH region 113, and the PDCCH of each time slot in the second time slot within a subframe is transmitted by using an LR-EPDCCH.

[0409] The PDSCH of the same time slot is scheduled by using the PDCCH of each time slot mapped to the existing PDCCH region in the first time slot within a subframe. The PDSCH of the same time slot is scheduled by using the PDCCH of each time slot mapped to the LR-EPDCCH in the second time slot within a subframe.

[0410] The PDCCH of each time slot in the first time slot within a subframe is transmitted by using an existing PDCCH region. Therefore, a method in which the data portion of 1 TTI, here the DCI of 1 time slot portion, is included in the PDCCH of each time slot can be used. In the method including the DCI of 1 time slot portion, Modification Example 1 of Embodiment 1 described above can be applied.

[0411] As Figure 19 In the example shown, when an LR-EPDCCH region is configured in the first time slot within a subframe, there is already an existing PDCCH region. Therefore, since it becomes a mapping to the physical resources after removing the existing PDCCH region, the physical resources in the frequency axis direction sometimes increase.

[0412] As Figure 20 In the example shown, by using the existing PDCCH region in the first time slot within a subframe, there is no need to configure an LR-EPDCCH region in this time slot. Therefore, compared with Figure 19 the example shown, an increase in resources can be further suppressed, and thus a reduction in the resources of the data channel can be further suppressed. Therefore, the throughput of the system can be further improved.

[0413] Embodiment 2.

[0414] Disclose Ack / Nack for uplink data. In the past, in LTE, since TTI = 1 subframe, HARQ was performed on a subframe basis. Therefore, in LTE, the PHICH for transmitting Ack / Nack for uplink data is also transmitted for each subframe.

[0415] Since the TTI is shorter than 1 subframe, HARQ for LR-UE needs to be performed in a unit shorter than 1 subframe.

[0416] However, in the case of performing HARQ in a unit shorter than 1 subframe, the existing LTE PHICH transmission method cannot be applied. In addition, in order to support the shortened TTI on the same carrier in LTE, it is necessary to strive for the coexistence of LR-UE and legacy UE. A method for solving the above problems is disclosed herein.

[0417] For LR-UE, HARQ is performed in TTI units. It is assumed that Ack / Nack for uplink data of LR-UE can be transmitted in slot units.

[0418] As a specific example of the Ack / Nack transmission method, eight types of (1) to (8) below are disclosed.

[0419] (1) Transmit using LR-PHICH.

[0420] (2) Multiplex and transmit in the LR-EPDCCH region.

[0421] (3) Transmit using LR-EPDCCH.

[0422] (4) Transmit using PHICH.

[0423] (5) Transmit the Ack / Nack corresponding to the previous slot using PHICH.

[0424] (6) Transmit using PDCCH.

[0425] (7) Transmit the Ack / Nack corresponding to the previous slot using PDCCH.

[0426] (8) A combination of (1) to (7) above.

[0427] Disclose a method of transmitting using the LR-PHICH of the specific example (1). A physical channel for transmitting Ack / Nack for uplink data of LR-UE is set. Sometimes this physical channel is referred to as "LR-PHICH". LR-PHICH can be transmitted in even-numbered slots or odd-numbered slots. The physical resources for LR-PHICH can be set in PRB units.

[0428] Map the LR-PHICH to the physical resource region where the existing PDSCH is mapped. The LR-PHICH is mapped while avoiding the PRB pairs where other channels are mapped. For the LR-PHICH in even-numbered time slots, the symbols (symbols 1 to 4) where the existing PDCCH is mapped are excluded from the mapping.

[0429] Figure 21 and Figure 22 is a diagram for explaining the transmission method of the LR-PHICH in Embodiment 2. Figure 21 Illustrates the case where the LR-PHICH is mapped to one PRB in the second time slot within a subframe. Figure 22 Illustrates the cases where the LR-PHICH is mapped to one PRB in the first and second time slots within a subframe respectively. In the first time slot within a subframe, the LR-PHICH is mapped to the symbols other than symbol 114 where the existing PDCCH is mapped.

[0430] Disclose a method for mapping the shortened TTI unit and time slot unit Ack / Nack to the LR-PHICH.

[0431] The Ack / Nack for the uplink data of the LR-UE is constituted by a predetermined number of bits and modulated. The orthogonal code is multiplied by the modulated data of each LR-UE, the Ack / Nack of multiple LR-UEs is multiplexed, and scrambled. These multiple LR-UEs are set as an LR-PHICH group.

[0432] From the bits of this Ack / Nack to the scrambling, the same method as that for the Ack / Nack of the uplink data of the conventional UE can be used. The Ack / Nack is constituted by 3 bits, BPSK modulation is performed, multiplexing based on the orthogonal code is performed, and scrambling with SF = 4 is performed. As a result, the scrambled data in one LR-PHICH group becomes 12 symbols. 8 LR-UEs are multiplexed in one LR-PHICH group.

[0433] By using the same method as the conventional UE, the structure of modulation and coding, or decoding and demodulation can be made one. Thereby, the complication of the communication system can be avoided, and it can be simply configured in terms of installation.

[0434] Map one or more LR-PHICH groups to the physical resources for the LR-PHICH.

[0435] The following discloses the mapping method. One or more resource element groups are set in the region of the LR-PHICH, i.e., within 1 PRB. This resource element group is set as an HREG. 1 HREG is constituted by one or more REs. Map one LR-PHICH group to one or more HREGs.

[0436] For example, the REs within 1 PRB are divided into 18 HREGs. The division method can use the same method as for EREG. The REs within 1 PRB are numbered from 0 to 17, and the REs with the same number form one HREG. It is also possible to exclude the RS within 1 PRB for numbering. If the RS is set to 12 REs, the number of REs included in 1 HEREG is 4.

[0437] When using the same modulation and coding method as a traditional UE, the number of symbols required for 1 LR-PHICH group is 12. Therefore, 1 LR-PHICH group can be mapped to 3 HREGs. 1 PRB is composed of 18 HREGs, so that 6 LR-PHICH groups can be mapped.

[0438] When the number of RSs is greater than 4, simply increase the number of HREGs for mapping 1 LR-PHICH group.

[0439] Thus, the LR-PHICH group can be mapped to the area of LR-PHICH, that is, within 1 PRB.

[0440] In the above example, within the area of LR-PHICH, that is, within 1 PRB, the LR-PHICHs of 48 LR-UEs can be accommodated. When more LR-UEs need to be accommodated, the physical resources for mapping LR-PHICH can be composed of multiple PRBs. The LR-PHICH area can be set using multiple PRBs within 1 time slot.

[0441] Other mapping methods are disclosed below.

[0442] The physical resources mapped with LR-PHICH are composed of multiple PRBs, and 1 LR-PHICH group is mapped into these multiple PRBs. These multiple PRBs are within the same time slot. These multiple PRBs can be composed continuously or discontinuously.

[0443] A set composed of multiple LR-PHICH areas can be set as the LR-PHICH set, where each LR-PHICH area is composed of one PRB. 1 LR-PHICH group is mapped into the LR-PHICH set.

[0444] For example, an LR-PHICH set composed of 3 one-PRB LR-PHICH regions is set. Within the LR-PHICH set, there are 3 PRBs. The LR-PHICH group is mapped to the entire LR-PHICH set. Mapping can be performed using the respective HREGs of each PRB. Since there are 3 PRBs in the entire LR-PHICH set, mapping is performed using a total of 3 HREGs. The 12 symbols required for the LR-PHICH group are mapped to the 3 HREGs.

[0445] In this case, 18 LR-PHICH groups can be mapped to 1 LR-PHICH set. Therefore, 144 LR-UEs can be accommodated in 1 LR-PHICH set.

[0446] Thereby, the LR-PHICH for 1 LR-UE can be dispersed and mapped in the frequency axis direction.

[0447] Thereby, frequency diversity gain can be obtained, and HARQ can be performed more reliably. Therefore, the data transmission speed can be increased.

[0448] In the past, a part of the PHICH setting information was mapped to the PBCH included in the MIB and broadcast. This is because PHICH is multiplexed with the symbols where PDCCH is mapped. This is because, in order for the UE to receive the PDCCH, it is necessary to identify the PHICH setting information.

[0449] However, the LR-PHICH is mapped avoiding the region where the PDCCH is mapped. Therefore, the setting information may not be included in the MIB. In addition, the setting information may not be mapped to the PBCH for broadcasting. Thereby, the amount of information of the MIB transmitted at high frequency can be reduced.

[0450] The following discloses a method for setting the LR-PHICH. Set the LR-PHICH region. It is also possible to set an LR-PHICH set. The resources on the frequency axis of the LR-PHICH set are set in units of PRBs. It is possible to set continuous PRBs or discontinuous PRBs.

[0451] The resources on the time axis of the LR-PHICH are set in units of shortened TTI instantslots. It is possible to set continuous slots or discontinuous slots. It is possible to set for each slot.

[0452] Use one slot to set the LR-PHICH region or the LR-PHICH set.

[0453] The LR-PHICH can be configured per cell, per LR-UE, or per group of LR-UEs, such as per LR-PHICH group. Additionally, it can be configured by the system according to standards. Or, it can be a combination of them.

[0454] For example, the configuration on the time axis and frequency axis of the LR-PHICH is per cell, and the configuration of the HREG number is per UE. The number of HREGs and the mapping method of REs within a PRB can be determined in advance by the system according to standards. Thus, the eNB can pre-configure the time slot timing and PRB of the LR-PHICH, making scheduling easier. The LR-UE can identify the time slot timing and PRB of the LR-PHICH configured per cell, and can identify the HREGs configured per UE within the time slot and PRB.

[0455] As another example, the configuration of resources where the LR-PHICH can be configured can be per cell. In fact, the LR-PHICH for the LR-UE can also be configured per UE. By pre-configuring the resources where the LR-PHICH can be configured per cell, the scheduling of the LR-PHICH to the same subframe as the legacy UE can be made easier. Additionally, the coexistence of the legacy UE and the LR-UE can be made easier.

[0456] The configuration of the LR-PHICH can be determined statically, or quasi-statically or dynamically.

[0457] In the case of static determination, it can be determined according to standards, etc. In the case of quasi-static or dynamic determination, RRC signaling can be used.

[0458] For example, for the per-cell configuration, it is pre-determined using standards, and for the per-UE configuration, it can be determined quasi-statically or dynamically using RRC signaling.

[0459] As another example, in the case of per-cell configuration, as broadcast information, it can be broadcast by the eNB to the UEs within the coverage area. In the case of per-LR-UE configuration, using UE-specific signaling, the eNB notifies the LR-UEs performing shortened TTIs.

[0460] The eNB can include the configuration information of the LR-PHICH in the RRC Connection Reconfiguration message and notify the LR-UE as RRC signaling.

[0461] Disclose the actions of the LR-UE. The LR-UE receives the PCFICH and identifies the symbol at the start of the PDSCH region in time slot #0.

[0462] The LR-UE detects its own LR-PHICH from the HREG number of its own LR-PHICH region. The structure of the LR-PHICH region and the HREG number are notified by the eNB using, for example, RRC signaling.

[0463] Thereby, the LR-UE can detect the LR-PHICH sent to itself and receive the Ack / Nack.

[0464] In the above example, it is disclosed that the eNB notifies the HREG number to the LR-UE and uses this HREG number to determine its own LR-PHICH.

[0465] As another example, the HREG number can be derived using the physical resources mapped with the uplink data corresponding to the LR-PHICH, i.e., the PUSCH. As the physical resources, there are RE numbers, PRB numbers, etc. Among them, for example, it can be determined as the smallest RE number, the smallest PRB number, etc.

[0466] Alternatively, the derivation can be performed using the control channel element number mapped with the scheduling information of the uplink data corresponding to the LR-PHICH, i.e., the PUSCH. It can be determined as the smallest control channel element number, etc.

[0467] Alternatively, the derivation can be performed using the cyclic shift number used in the demodulation RS of the uplink data corresponding to the LR-PHICH, i.e., the PUSCH. Alternatively, the derivation can be performed using a combination of them.

[0468] The eNB performs scheduling or mapping taking the above numbers into consideration. Thereby, even if the LR-UE is not explicitly notified of the HREG number, it can derive its own HREG number and determine its own LR-PHICH.

[0469] In addition, by adopting the above structure, the Ack / Nack for the uplink data of the LR-UE can be sent, and the HARQ for the uplink data can be performed in a shortened TTI unit. In addition, the HARQ for the uplink data can be performed in a time slot unit. Therefore, it can reduce the delay time and can improve the data transmission speed.

[0470] Disclose a method for transmitting in the LR-EPDCCH region reused for the specific example (2).

[0471] The Ack / Nack for the LR-UE is multiplexed and mapped to the physical resources mapped with the LR-EPDCCH. The PHICH for the LR-UE and the PDCCH for the LR-UE are multiplexed within 1 PRB mapped with the LR-EPDCCH.

[0472] Disclosed is a multiplexing method. Multiplexing can be performed on a per RE basis. One or more LR-EREGs of the LR-EPDCCH are used for the PHICH for the LR-UE. In other words, instead of using one or more LR-EREGs for the mapping of the LR-EPDCCH, they are used for the mapping of the PHICH for the LR-UE. In other words, one or more LR-EREGs are used as the HREGs for mapping the PHICH for the LR-UE.

[0473] The method for constructing the LR-EPDCCH can apply the above method. As the method for constructing the LR-EREG, a method of constructing 16 groups of LR-EREG = 0 to 15 within the PRB is more preferable. This is because, when the existing modulation and coding methods are used for Ack / Nack, the number of REs required for 1 HREG is 4. Therefore, in this method, the number of REs within 1 LR-EREG becomes equal or close.

[0474] In addition, as the LR-EPDCCH set, 3 can be set. Thus, it can be used to construct 3 HREGs.

[0475] The method for determining the HREG can apply the method for determining the HREG within the above LR-PHICH.

[0476] Thus, there is no need to newly set up the physical resource area for the LR-PHICH. Therefore, the eNB does not need to notify the LR-UE of the structure of the LR-PHICH, and thus the signaling amount can be reduced.

[0477] Figure 23 and Figure 24 is a diagram for explaining the method of multiplexing and transmitting Ack / Nack to the LR-EPDCCH area in Embodiment 2. In this embodiment, the Ack / Nack for the uplink data is mapped to the PHICH for the LR-UE and multiplexed to the LR-EPDCCH area for transmission.

[0478] Figure 23 Shows the case where the PHICH for the LR-UE is multiplexed to the LR-EPDCCH area and mapped in the second time slot within the subframe. Figure 24 Shows the case where the PHICH for the LR-UE is multiplexed to the LR-EPDCCH area and mapped in the first and second time slots within the subframe respectively. In the first time slot within the subframe, the PHICH for the LR-UE is multiplexed to the LR-EPDCCH other than the symbols where the existing PDCCH is mapped and mapped.

[0479] Accordingly, it is possible to transmit Ack / Nack for the uplink data of the LR-UE, and HARQ for the uplink data can be performed in units of shortened TTIs. In addition, HARQ for the uplink data can be performed in units of time slots. Therefore, it is possible to reduce the latency time and improve the data transmission speed.

[0480] Disclosed is a method of transmitting using the LR-EPDCCH of the specific example (3). The transmission of Ack / Nack for the uplink data of the LR-UE is performed only through scheduling in the LR-EPDCCH. It is also possible not to provide the PHICH for the LR-UE.

[0481] Information indicating whether it is new data is included in the DCI for the LR-UE. The DCI is mapped to the LR-EPDCCH. The LR-UE receives the LR-EPDCCH sent to itself, and by receiving this information in the DCI, it can identify whether the scheduling is for new data or retransmitted data. When this information indicates new data, the LR-UE transmits new data according to this scheduling. In this case, the LR-UE can be regarded as an Ack. When this information indicates not new data, the LR-UE transmits retransmitted data according to this scheduling. In this case, the LR-UE can be regarded as a Nack.

[0482] Accordingly, it is possible to transmit Ack / Nack for the uplink data of the LR-UE, and HARQ for the uplink data can be performed in units of shortened TTIs. In addition, HARQ for the uplink data can be performed in units of time slots. Therefore, it is possible to reduce the latency time and improve the data transmission speed.

[0483] In addition, it is possible not to provide the LR-PHICH, and it is also possible not to provide the area for the LR-PHICH. Therefore, it is possible to increase the physical resources for data and further strive to improve the data transmission speed.

[0484] Disclosed is a method of transmitting using the PHICH of the specific example (4). In the even-numbered time slots of the time slot #, the PHICH of the conventional UE is mapped. In this method, the PHICH of the LR-UE is also mapped to the area where this PHICH is mapped. The PHICH of the LR-UE can also be mapped to the physical resources of the PHICH using the same method as the conventional UE.

[0485] Accordingly, it is possible to transmit Ack / Nack for the uplink data of the LR-UE, and HARQ for the uplink data can be performed.

[0486] In addition, it is possible not to provide the area for the LR-PHICH. Therefore, it is possible to increase the physical resources for data and improve the data transmission speed.

[0487] Disclosed is a method for publicly using PHICH to send Ack / Nack corresponding to the previous time slot. In the even-numbered time slots, PHICH of a conventional UE is mapped. In this method, the PHICH corresponding to the previous time slot of the LR-UE is also mapped to the area where this PHICH is mapped. The PHICH corresponding to the previous time slot of the LR-UE can also be mapped to the physical resources of the PHICH using the same method as that of the conventional UE.

[0488] The LR-UE prestores the uplink data corresponding to the PHICH corresponding to the previous time slot. When the LR-UE receives the PHICH of the even-numbered time slot, it can identify the Ack / Nack of the uplink data corresponding to the PHICH corresponding to the previous time slot. Therefore, by prestoring the uplink data corresponding to the PHICH corresponding to the previous time slot, the LR-UE can send new data or retransmit data according to the PHICH of the even-numbered time slot.

[0489] Thereby, it is possible to send Ack / Nack for the uplink data of the LR-UE and perform HARQ for the uplink data.

[0490] In addition, an area for LR-PHICH may not be set. Therefore, it is possible to increase the physical resources for data and improve the data transmission speed.

[0491] Disclosed is a method for sending using the PDCCH of the specific example (6). In this method, the sending of Ack / Nack for the uplink data of the LR-UE is performed only through scheduling in the PDCCH. Use the scheduling method using the PDCCH described above or hereinafter. Adopt the scheduling method of the PUSCH using the PDCCH. It is performed using the DCI of the data for each TTI of the LR-UE. Thereby, it is possible to send Ack / Nack for each time slot. Information indicating whether it is new data is included in the DCI of the data for each TTI of the LR-UE. The DCI is mapped to the PDCCH. The LR-UE receives the PDCCH sent to itself and can identify whether the scheduling is for new data or retransmitted data by receiving this information in the DCI. When this information indicates new data, the LR-UE sends new data according to this scheduling. In this case, the LR-UE can be regarded as an Ack. When this information indicates not new data, the LR-UE sends retransmitted data according to this scheduling. In this case, the LR-UE can be regarded as a Nack.

[0492] In the case where scheduling information of data for each TTI of 2 TTIs for the LR-UE is included in the DCI, information indicating whether it is new data can be included in a manner corresponding to the data of each TTI. The DCI is mapped to the PDCCH. The LR-UE receives the PDCCH sent to itself, and by receiving this information in the DCI, it can identify whether the scheduling of each time slot is for new data or for retransmitted data. When this information indicates new data, the LR-UE transmits new data in the corresponding time slot according to this scheduling. In this case, the LR-UE can be regarded as an Ack. When this information indicates not new data, the LR-UE transmits retransmitted data in the corresponding time slot according to this scheduling. In this case, the LR-UE can be regarded as a Nack.

[0493] Thereby, it is possible to send Ack / Nack for the uplink data of the LR-UE and perform HARQ for the uplink data.

[0494] In addition, the LR-PHICH may not be provided, and the area for the LR-PHICH may not be provided either. Therefore, it is possible to increase the physical resources for data and improve the data transmission speed.

[0495] Disclose a method of sending Ack / Nack corresponding to the previous time slot using the PDCCH of the specific example (7).

[0496] In this method, the sending of Ack / Nack for the uplink data of the LR-UE is performed only through the scheduling in the PDCCH. The LR-UE is scheduled to send Ack / Nack that should be performed in a predetermined time slot using the PUSCH scheduling of the PDCCH of the next time slot. In other words, using the PUSCH scheduling of the PDCCH performed in a predetermined time slot, the Ack / Nack that should be performed in the previous time slot is sent. A PUSCH scheduling method can also be applied, and this PUSCH scheduling method uses the PDCCH applying the method disclosed in the modified example 3 of Embodiment 1. Using the PUSCH scheduling of the PDCCH of time slot #even, the Ack / Nack that should be performed in the previous time slot #odd is sent.

[0497] The DCI including the scheduling information of PUSCH using the PDCCH in the even-numbered slots for the LR-UE includes information indicating whether the uplink data corresponding to the Ack / Nack corresponding to the previous slot is new data. The LR-UE receives the PDCCH sent to itself in the even-numbered slots, and by receiving this information in the DCI, it can identify whether the scheduling is for new data or retransmitted data. When this information indicates new data, the LR-UE sends new data according to this scheduling. In this case, the LR-UE can be regarded as an Ack. When this information indicates not new data, the LR-UE sends retransmitted data according to this scheduling. In this case, the LR-UE can be regarded as a Nack.

[0498] The LR-UE pre-stores the uplink data corresponding to the Ack / Nack corresponding to the previous slot. When the LR-UE receives the PDCCH in the even-numbered slot, it can identify the Ack / Nack corresponding to the previous slot. Therefore, by pre-storing the uplink data corresponding to the Ack / Nack corresponding to the previous slot, the LR-UE can send new data or retransmitted data according to the Ack / Nack in the even-numbered slot.

[0499] Thus, it is possible to send Ack / Nack for the uplink data of the LR-UE and perform HARQ for the uplink data.

[0500] In addition, the LR-PHICH may not be set, and the area for the LR-PHICH may not be set either. Therefore, the physical resources for data can be increased, and it is possible to improve the data transmission speed.

[0501] In addition, by applying the case where the PDCCH for the LR-UE is only mapped to the even-numbered slots, the PDCCH can not be mapped to the odd-numbered slots, and the PDCCH area can not be set in the odd-numbered slots. Thus, it is possible to avoid an increase in the physical resources for control and increase the physical resources for data.

[0502] The specific examples (1) to (7) may also be combined. For example, the method of the specific example (4) or the specific example (5) is used in the even-numbered slots, and any of the methods of the specific examples (1) to (3) is used in the odd-numbered slots.

[0503] Since there is a PDCCH area in the even-numbered slots, the physical resources allocated to the LR-PHICH in 1 PRB are fewer. Therefore, the following situation will occur: more physical resources are required on the frequency axis within this slot to send the LR-PHICH.

[0504] By applying the method using the PHICH of the specific example (4) or the PHICH of the specific example (5) in the even-numbered time slots, it is possible to suppress the increase in the physical resources allocated to LR-PHICH in the even-numbered time slots. Therefore, the physical resources allocated to data can be increased, and the data transmission speed can be improved.

[0505] Embodiment 3.

[0506] The uplink shared channel PUSCH mapped with the data of the legacy UE is mapped to the physical resources in subframe units. In the current LTE standard, the PUSCH of the legacy UE is mapped to the physical resources in the form of PRB pairs (PRB pair).

[0507] A PRB is a Physical Resource Block. Similar to the downlink, it consists of 12 subcarriers in the frequency axis direction and the physical resources of 1 time slot in the time axis direction. A PRB pair consists of 2 PRBs on the time axis (refer to Non-Patent Document 9).

[0508] Figure 25 It is a diagram for explaining the mapping of the existing PUSCH and PUCCH to the physical resources. Figure 25 In the example shown, 1 time slot consists of 7 symbols. Therefore, 1 subframe consists of 14 symbols. The PUCCH is mapped to both ends in the frequency axis direction. The PUSCH is mapped to the frequency region between the PUCCHs at both ends in the frequency axis direction.

[0509] 1 PRB consists of 12 subcarriers in the frequency axis direction and the physical resources of 1 time slot in the time axis direction.

[0510] As Figure 25 shown, the existing PUSCH is mapped to a PRB pair consisting of 2 PRBs of 2 time slots. As shown by the arrows 121 and 122, it has a structure of hopping frequency between two time slots within a subframe and a structure of hopping frequency between subframes.

[0511] In addition, the PUCCH is mapped to a PRB pair consisting of two PRBs of two time slots. As shown by the arrow 120, it hops frequency between two time slots within a subframe. The PUCCH is set in subframe units.

[0512] In addition, the PUSCH is scheduled by the PDCCH. The PDCCH is mapped to the PDCCH region. That is, the physical resources mapped with the PUSCH are scheduled in PRB pair units. In terms of time, it is scheduled in 1 subframe units.

[0513] However, for a UE (LR-UE) that operates with a shortened TTI, since the TTI is shorter than one subframe, the mapping method of the conventional UE cannot be applied to the mapping of its PUSCH to physical resources, and a new method is required.

[0514] In addition, in order to support a shortened TTI on the same carrier in LTE, it is necessary to strive to achieve coexistence between LR-UEs and conventional UEs. The following discloses a method for solving the above problems.

[0515] Map the PUSCH of the LR-UE to the physical resource region where the existing PUSCH is mapped in units of PRBs. One or more PRBs can be used for one PUSCH.

[0516] In the current LTE, SC-FDMA is used for the uplink. Therefore, in the case of using multiple PRBs for the PUSCH of the LR-UE, consecutive PRBs can be used. Thus, the PUSCH of the LR-UE can be mapped while maintaining a low peak-to-average power ratio (PAPR).

[0517] In the future, in the case of using OFDMA for the uplink, similar to the PDSCH in the downlink, consecutive PRBs or non-consecutive PRBs can be used. By using consecutive PRBs in the frequency band with excellent uplink communication quality, high-speed transmission can be achieved. Or, by using non-consecutive PRBs, frequency diversity gain can be obtained, and the communication quality can be improved.

[0518] The PUSCH of the LR-UE is mapped to avoid the PRB pairs where the PUSCH of the conventional UE is mapped.

[0519] The demodulation reference signal (RS) of the uplink can be mapped to the same symbol as the demodulation RS of the PUSCH of the existing conventional UE. Thus, the method of inserting RS into the PUSCH becomes one that can be easily controlled.

[0520] Figure 26 It is a diagram for explaining the mapping of the PUSCH of the LR-UE to physical resources in Embodiment 3.

[0521] As Figure 26 shown, the PUSCH of the conventional UE is mapped to a PRB pair composed of two PRBs in two time slots within a subframe. As shown by arrow 132, the conventional UE #1 performs frequency hopping between subframes. As shown by arrows 131 and 133, the conventional UE #2 performs frequency hopping between two time slots within a subframe.

[0522] The PUSCH of the LR-UE is mapped in terms of PRB per time slot. In the first time slot of subframe #1, LR-UE#1, LR-UE#2, and LR-UE#3 are mapped. In the second time slot, LR-UE#1 is mapped. In the first time slot of subframe #2, LR-UE#1 and LR-UE#2 are mapped. In the second time slot, LR-UE#2 is mapped. As shown by reference numeral "130", there are physical resources that are not scheduled in terms of PRB.

[0523] The PUSCH of the traditional UE is scheduled in terms of subframe and allocated to physical resources in terms of subframe. The control information for scheduling, including the allocation information for allocating the PUSCH to physical resources, is included in DCI (Downlink Control Information). The DCI is mapped to the PDCCH (refer to Non-Patent Document 10).

[0524] However, for the LR-UE, the shortened TTI is shorter than 1 subframe, and the allocated physical resources are also shorter than 1 subframe. Therefore, the scheduling method of the traditional UE cannot be applied.

[0525] In addition, in order to support the shortened TTI on the same carrier in LTE, it is necessary to strive for the coexistence of the LR-UE and the traditional UE.

[0526] As a method to solve the above problems, the scheduling method of the above PDSCH can be applied.

[0527] For the LR-UE, the data for each shortened TTI is scheduled. For the PUSCH of the LR-UE, it is scheduled per shortened TTI. When TTI = 1 time slot, it is scheduled in terms of time slot. For the PUSCH of the LR-UE, it is allocated to physical resources in terms of time slot. HARQ is performed in terms of TTI. For the LR-UE, HARQ is performed in terms of time slot. For the traditional UE, HARQ is performed in terms of subframe.

[0528] The scheduling method of the PUSCH of the LR-UE can also apply the scheduling method of the PDSCH of the above LR-UE.

[0529] It is only necessary to appropriately correspond the PDSCH and the PUSCH, and apply the scheduling information of the PDSCH included in the DCI of the LR-UE and the scheduling information of the PUSCH correspondingly.

[0530] By scheduling the PUSCH of the LR-UE for each shortened TTI, for example, scheduling the LR-UE with PDCCH or LR-EPDCCH, the data of each shortened TTI of the LR-UE can be scheduled. Therefore, the transmission speed of the data from the LR-UE can be improved. In addition, on the same carrier of LTE, the shortened TTI can be supported for the LR-UE, and coexistence with the legacy UE can be achieved.

[0531] Embodiment 4.

[0532] The PUCCH of the legacy UE is scheduled in subframe units and allocated to physical resources in subframe units. However, the shortened TTI for the LR-UE is shorter than 1 subframe, and the allocated physical resources are also shorter than 1 subframe. Therefore, the PUCCH of the legacy UE cannot be applied. In addition, in order to support the shortened TTI on the same carrier of LTE, it is necessary to strive to achieve coexistence between the LR-UE and the legacy UE. In this embodiment, a method for solving the above problems is disclosed.

[0533] Map the PUCCH of the LR-UE (hereinafter sometimes referred to as "LR-PUCCH") to the physical resource area where the existing PUSCH is mapped in units of PRBs. One or more PRBs can be used.

[0534] In the current LTE, SC-FDMA is used for the uplink. In the case of using the multi-access method of a single carrier as described above, when multiple PRBs are used for the PUCCH of the LR-UE, consecutive PRBs can be used. Thereby, the PUCCH of the LR-UE can be mapped while maintaining a low PAPR.

[0535] In the future, in the case of using a multi-carrier multi-access method such as OFDMA for the uplink, consecutive PRBs can be used, or non-consecutive PRBs can be used. By using consecutive PRBs in the frequency band with excellent communication quality in the uplink, high-speed transmission can be performed. Or, by using non-consecutive PRBs, frequency diversity gain can be obtained, and an attempt is made to improve the communication quality.

[0536] The LR-PUCCH is mapped avoiding the physical resources where the PUCCH of the legacy UE is mapped. The physical resources where the LR-PUCCH is mapped can be mapped to a frequency closer to the inside of the system band than the physical resources where the PUCCH of the legacy UE is mapped. Thereby, the legacy UE and the LR-UE can coexist without changing the scheduling of the physical resources of the PUCCH of the legacy UE.

[0537] The physical resources mapped with LR-PUCCH and the physical resources mapped with the PUCCH of a traditional UE can be mapped continuously on the frequency axis. Thus, in the case of using a single-carrier multiple access method, the PUSCH region will not be discrete, so the utilization efficiency of the uplink physical resources can be improved, and the capacity of the cell can be increased.

[0538] The demodulation RS for the uplink can be mapped to the same symbol as the demodulation RS of the PUCCH of an existing traditional UE. Thus, a method of inserting RS into the PUCCH becomes one that can be easily controlled.

[0539] In the physical resource region mapped with LR-PUCCH, the PUCCHs of multiple LR-UEs can be multiplexed. For example, frequency division multiplexing or code division multiplexing can be performed.

[0540] The resources of the LR-PUCCH for the Ack / Nack of the PDSCH for each LR-UE can be derived as the physical resource region mapped with the above LR-PUCCH by using the predetermined CCE number of the PDCCH of the LR-UE that schedules the PDSCH. In the case where the PDSCH is scheduled by the LR-EPDCCH, an offset in the frequency axis direction can be further set and derived as the physical resource region mapped with the above LR-PUCCH. The offset value can be notified by the eNB to the LR-UE. The notification from the eNB to the LR-UE can use RRC signaling or the LR-EPDCCH. It can be notified by including it in the DCI for the scheduling of the PDSCH.

[0541] Figure 27 It is a diagram for explaining the mapping of the PUCCH of the LR-UE in Embodiment 4 to the physical resources. In Figure 27 In the example shown, the physical resource region mapped with LR-PUCCH is continuously formed inside the frequency region mapped with the existing PUCCH. The LR-PUCCH is mapped per time slot. In the first time slot within the subframe, the LR-PUCCH of LR-UE#2 is mapped to the physical resource region on one side for LR-PUCCH, and the LR-PUCCH of LR-UE#3 is mapped to the physical resource region on the opposite side for LR-PUCCH. In the second time slot within the subframe, the LR-PUCCH of LR-UE#1 is mapped to the physical resource region on one side for LR-PUCCH, and the LR-PUCCH of LR-UE#4 is mapped to the physical resource region on the opposite side for LR-PUCCH.

[0542] In Figure 27In the example shown, the physical resource region of the LR-PUCCH is formed on both sides of the frequency axis, but it can also be formed only on one side of the frequency axis. The above structure is effective when the communication quality is excellent and frequency hopping is not required. The physical resources allocated to the PDSCH can be increased, so the throughput of the system can be increased.

[0543] The uplink control information (UCI) of the LR-UE includes information in time slot units. The UCI of the LR-UE can be modulated and encoded in the same way as before. By using the same method as the conventional UE, the complexity of control can be avoided. In addition, in the eNB, the installation of the receiving part of the PUCCH can be simplified.

[0544] For the conventional UE, 1 subframe is used to map the UCI transmitted by the PUCCH to the physical resources, while for the LR-UE, 1 time slot is used to map the UCI to the physical resources.

[0545] However, when the UCI of the LR-UE is modulated and encoded in the same way as before, sometimes the required physical resources are insufficient in the time axis direction. In this case, it can be dealt with by increasing the physical resources in the frequency axis direction and mapping them to the increased physical resources. Just increase the number of PRBs within 1 time slot. In the case of a single carrier, continuous PRBs can be used. In the case of multiple carriers, continuous PRBs can be used, or discontinuous PRBs can also be used.

[0546] In addition, as another method, the amount of information of the UCI of the LR-UE can also be reduced to reduce the required amount of physical resources. Or, as another method, the modulation method or coding method can be changed to reduce the required physical resources. It can be reduced to be the same as the amount of physical resources on the frequency axis of the existing PUCCH. Thus, the physical resources required for the control channel can be reduced, and the physical resources that the data channel can be mapped to can be increased. Therefore, the data transmission speed can be improved.

[0547] In the mapping of the PUCCH of the conventional UE to the physical resources, as shown by the arrows 140 and 141, frequency hopping between time slots is performed to obtain frequency diversity gain. However, since the PUCCH of the LR-UE is mapped within 1 time slot, frequency hopping between time slots cannot be performed. The method to solve this problem is disclosed below.

[0548] The symbols within a time slot are divided into multiple groups. Frequency hopping can be performed among these groups. Regarding how to group the symbols within a time slot, it can be determined statically in advance according to standards, etc., or quasi-statically or dynamically. In the case of quasi-static or dynamic determination, it can be determined by the eNB, and the determined grouping information is notified from the eNB to the UE. For the notification method, it can be notified using RRC signaling, or it can be notified using PDCCH or LR-EPDCCH. Or, it can be a combination of them. For example, a list of groupings can be determined in advance according to standards, and the eNB determines which group to use and notifies it to the UE. Thereby, the signaling amount can be reduced.

[0549] Figure 28 It is a diagram for explaining another mapping method of mapping the PUCCH of the LR-UE in Embodiment 4 to physical resources.

[0550] In Figure 28 In the example shown, a physical resource area mapped with LR-PUCCH is continuously formed inside the frequency area where the existing PUCCH is mapped. LR-PUCCH is mapped per time slot. In addition, in Figure 28 In the example shown, a group consisting of two consecutive symbols is formed within a time slot, and LR-PUCCH performs frequency hopping among the groups of symbols within the time slot as shown by arrow 145. Thereby, a frequency diversity gain can be obtained, and the communication quality of PUCCH can be improved.

[0551] The setting method of LR-PUCCH can also apply the setting method of the existing PUCCH. The setting of the existing PUCCH is performed by setting the PRB structure in units of 1 subframe. However, for the setting of LR-PUCCH, instead, it is only necessary to set the PRB structure in units of 1 time slot.

[0552] The notification method for notifying the LR-PUCCH structure from the eNB to the LR-UE can apply the notification method of the existing PUCCH structure.

[0553] The LR-UE maps the UCI in units of time slots to LR-PUCCH using the LR-PUCCH structure notified by the eNB and transmits it to the eNB.

[0554] Thereby, the UCI of each shortened TTI of the LR-UE can be mapped to PUCCH, and this PUCCH can be mapped to physical resources per shortened TTI.

[0555] PUCCH is also used to send Ack / Nack for downlink data. Therefore, HARQ for downlink data in the shortened TTI of the LR-UE can be performed. Therefore, it is possible to reduce the delay time and improve the data transmission speed.

[0556] In addition, it enables an LR-UE and a traditional UE to coexist on the same carrier in LTE.

[0557] Embodiment 5.

[0558] The SRS (Sounding Reference Signal) of a traditional UE is scheduled in units of subframes and is allocated to the last symbol within the subframe. However, the shortened TTI for an LR-UE is shorter than 1 subframe. Sometimes, the shortened TTI cannot be accommodated in the SRS in units of subframes. Therefore, an SRS that can handle the shortened TTI is required. In addition, in order to support the shortened TTI on the same carrier in LTE, it is necessary to strive for the coexistence of an LR-UE and a traditional UE. In this embodiment, a method for solving the above problems is disclosed.

[0559] The SRS for an LR-UE can be configured in units of time slots. In addition, the SRS for an LR-UE can be set in units of time slots. The SRS for an LR-UE can be mapped to physical resources in units of time slots.

[0560] Any one symbol within a time slot constitutes the SRS. It can also be set as the last one symbol within the time slot. The symbol number constituting the SRS can be different for each time slot. For example, in even-numbered time slots, the SRS of the LR-UE is constituted in the last symbol within the time slot, and in odd-numbered time slots, the SRS of the LR-UE is constituted in the first symbol within the time slot.

[0561] When the SRS of the LR-UE is constituted in the last symbol within the time slot of an odd-numbered time slot, it will conflict with the SRS of the traditional UE. To avoid this situation, frequency division multiplexing can be performed on the SRS of the LR-UE and the SRS of the traditional UE.

[0562] The method for constituting the SRS of the LR-UE can apply the method for constituting the SRS of the traditional UE. Thus, even when the SRS of the LR-UE is constituted in the last symbol within the time slot of an odd-numbered time slot, the SRS of the LR-UE and the SRS of the traditional UE can coexist.

[0563] Figure 29 It is a diagram for explaining the method for constituting the SRS of the LR-UE in Embodiment 5. In Figure 29 In the example shown, the SRS of the LR-UE is constituted in the last symbol within each time slot. The last symbol of the subframe, that is, the last symbol of the second time slot within the subframe, constitutes the SRS of the existing traditional UE. Therefore, in Figure 29In the example shown, the SRS of the LR-UE is also constituted in this symbol. The SRS of the conventional UE and the SRS of the LR-UE are multiplexed in this symbol. Thus, the SRS of the conventional UE and the SRS of the LR-UE can coexist. The LR-UE can transmit the SRS using the symbol that constitutes this SRS.

[0564] In Figure 29 In the example shown, as indicated by arrows 151 and 153, the conventional UE performs frequency hopping between two time slots within a subframe. As indicated by arrow 152, the conventional UE performs frequency hopping between subframes. As indicated by the reference numeral "150", there is physical resource that is not scheduled in units of PRB.

[0565] An example of a method for setting the SRS is disclosed. The SRS in units of time slots is set for the LR-UE. It can be set per cell or per UE. Alternatively, a part of the SRS structure can be set per cell, and the remaining part of the SRS structure can be set per UE. The eNB notifies the LR-UE of the setting information of the SRS in units of time slots. RRC signaling, PDCCH, or LR-EPDCCH can be used. In the case of setting per cell, it can be included in the system information and broadcast. The system information is MIB or SIB. In the case of setting individually for each UE, it can be notified using dedicated RRC signaling. In the case of setting individually for each UE, this information can be included in the DCI and notified using PDCCH or LR-EPDCCH.

[0566] For example, the eNB initially sets the SRS structure per cell. The eNB then sets the SRS structure separately for each LR-UE therein.

[0567] For example, as the SRS structure per cell, it can be set as resource information on the time axis. It can be set as information for determining in which time slot the SRS is constituted. As an example of the information for determination, there are system frame number (SFN), radio frame number, time slot number, symbol number, offset value of the radio frame within the system frame, offset value of the time slot within the subframe, and interval between time slots, etc. Thus, the LR-UE can determine the time slot that constitutes the SRS per cell.

[0568] As the SRS structure per UE, it can be set as resource information on the frequency axis. It is only necessary to set it as information for determining in which PRB the SRS is constituted. As an example of the information for determining in which PRB the SRS is constituted, there is PRB number, etc. Alternatively, it can be set as information for determining in which subcarrier the SRS is constituted. As an example of the information for determining in which subcarrier the SRS is constituted, there is subcarrier number, etc.

[0569] In addition, as the SRS structure for each UE, it can be set as information on the multiplexing method with other LR-UEs or traditional UEs. For example, in the case of frequency-division multiplexing with other LR-UEs or traditional UEs within 1 PRB, it is only necessary to set it as information capable of determining the resources on the frequency axis that constitute its own SRS. Information for determining the said resources includes, for example, the offset value of subcarriers, subcarrier spacing, etc.

[0570] The LR-UE uses the above SRS structure notified by the eNB to map the SRS to physical resources and transmit it.

[0571] The LR-UE does not use the symbol that constitutes the SRS in time-slot units to transmit data. It does not map data to this symbol.

[0572] It can be set not to use this symbol to transmit data. As this symbol, it is not only the symbol of the SRS structure set individually for each LR-UE, but also the symbol of the SRS structure set for each cell. It is possible not to map data using this symbol.

[0573] In addition, the LR-UE can refrain from using the symbol that constitutes the SRS of a traditional UE to transmit data. It is possible not to map data to this symbol.

[0574] It can be set not to use this symbol to transmit data. As this symbol, it is set as the symbol of the SRS structure set for each cell. It is possible not to map data using this symbol.

[0575] The LR-UE can receive the SRS structure set for each cell for traditional UEs from the eNB.

[0576] Thereby, it is possible to avoid the situation where its own transmitted data conflicts with its own SRS or the SRS of a traditional UE.

[0577] When the SRS for the LR-UE is constituted in any one symbol within a time slot, a situation of conflict with the uplink data of a traditional UE will occur. In this case, the communication quality of the uplink data of the traditional UE and the accuracy of the SRS of the LR-UE will deteriorate. A method for solving the above problems is disclosed.

[0578] In the PRB region where the PUSCH of a traditional UE is transmitted, the SRS of the LR-UE is not constituted. In the PRB region where the PUSCH of a traditional UE is transmitted, the eNB can refrain from setting the SRS of the LR-UE.

[0579] The LR-UE uses at least one of the PRB mapped with the PUSCH for the LR-UE and the PRB not mapped with any data to transmit the SRS.

[0580] Figure 30This is a diagram for explaining the method of configuring the SRS of the LR-UE in Embodiment 5. In the PRB region for transmitting the PUSCH of a conventional UE, the SRS of the LR-UE is not configured. In Figure 30 In the example shown, in the first time slot within Subframe #1, the SRS of the LR-UE is not configured in the last symbol of the PRB where the PUSCH of the conventional UE is mapped. The SRS of the LR-UE is configured in the last symbol of the PRB where the PUSCH of the LR-UE is mapped.

[0581] In the first time slot within Subframe #2, the SRS of the LR-UE is not configured in the last symbol of the PRB where the PUSCH of the conventional UE is mapped. The SRS of the LR-UE is configured in the last symbols of the PRB where the PUSCH of the LR-UE is mapped and the PRB where no scheduling is performed.

[0582] In Figure 30 In the example shown, in Subframe #1 and Subframe #2, the SRS of the conventional UE is configured in the last symbol of the second time slot within the subframe. The SRS of the LR-UE is also configured in this symbol. The SRS of the conventional UE and the SRS of the LR-UE are multiplexed in this symbol.

[0583] Thus, it is possible to avoid the situation where the PUSCH of the conventional UE and the SRS transmission of the LR-UE conflict. In addition, the SRS of the conventional UE and the SRS of the LR-UE can coexist. In addition, the LR-UE can transmit the SRS using the symbol in which the SRS is configured.

[0584] In Figure 30 In the example shown, as indicated by arrows 156 and 158, the conventional UE performs frequency hopping between two time slots within the subframe. As indicated by arrow 157, the conventional UE performs frequency hopping between subframes. As indicated by reference numeral "155", there is physical resource that is not scheduled in PRB units.

[0585] The eNB schedules the PUSCH for the conventional UE, so it identifies the PRB where the PUSCH is mapped. Therefore, the eNB can configure the SRS for the LR-UE avoiding the PRB where the PUSCH of the conventional UE is mapped.

[0586] Alternatively, as the structure of the SRS per cell for the LR-UE, the eNB can configure it in the PRB where the PUSCH of the conventional UE is mapped, but as the setting of the SRS per LR-UE, the eNB can perform the setting avoiding the PRB where the PUSCH of the conventional UE is mapped.

[0587] The LR-UE transmits the SRS according to the setting of its own SRS notified by the eNB.

[0588] By using the above method, the LR-UE can avoid recognizing the PUSCH regions of other LR-UEs. Therefore, the complication of the control of the LR-UE can be avoided.

[0589] As another method, the eNB can notify the LR-UE of the PUSCH region information of other LR-UEs. Alternatively, the eNB can notify the LR-UE of the region information where no mapping is performed. As the PUSCH region information and the region information where no mapping is performed, there is a PRB number, etc. The LR-UE that receives this information can use this region to transmit the SRS.

[0590] For example, the eNB notifies the slot structure as the SRS structure for the LR-UEs in each cell. Then, the eNB notifies each LR-UE of at least one of the SRS setting information, the PUSCH region information of other LR-UEs, and the region information where no mapping is performed.

[0591] The LR-UE uses the above information received from the eNB and transmits the SRS on at least one of the PRBs mapped with the PUSCH for the LR-UE and the PRBs where no mapping is performed, according to its own SRS setting.

[0592] By using the above method, the LR-UE can avoid transmitting the SRS on the PRBs mapped with the PUSCH of the legacy UEs.

[0593] When the eNB notifies each LR-UE of the PUSCH region information of other LR-UEs, it can also pre-guarantee the physical resource region mapped with the PUSCH of the LR-UE in advance. However, pre-guaranteeing the physical resource region will not be able to flexibly respond to the load conditions and radio wave transmission conditions that change over time, and sometimes it will lead to a decrease in the usage efficiency of the physical resources.

[0594] As a method to solve the above problems, the setting of the SRS can be performed dynamically. When it is necessary for the LR-UE to transmit the SRS, the eNB notifies the LR-UE of the SRS transmission request.

[0595] The SRS transmission request can be notified to the LR-UE by using the PDCCH or the LR-EPDCCH. It can also be notified by including it in the DCI of each time slot. At least one of the SRS setting information, the PUSCH region information of other LR-UEs, and the region information where no mapping is performed is notified together with the SRS transmission request.

[0596] The LR-UE receives the PDCCH or LR-EPDCCH sent to itself from the eNB. Upon receiving the transmission request for the SRS and the above information, the LR-UE uses the uplink time slot corresponding to the time slot in which the PDCCH or LR-EPDCCH was sent to transmit the SRS based on the received information.

[0597] Instead of notifying the transmission request for the SRS, it is also possible to notify at least one of the SRS setting information, the PUSCH region information of other LR-UEs, and the region information with no mapping. The LR-UE can determine to transmit the SRS based on the reception of this information. Thereby, the information used for the request can be reduced.

[0598] Alternatively, it is possible to notify only the transmission request for the SRS and the SRS setting information, without notifying at least one of the PUSCH region information of other LR-UEs and the region information with no mapping.

[0599] As described above, the eNB schedules the PUSCH for legacy UEs, and thus identifies the PRBs mapped with the PUSCH. The eNB can set the SRS for the LR-UE while avoiding the PRBs mapped with the PUSCH of legacy UEs. In this case, the eNB only needs to notify the transmission request for the SRS and the SRS setting information.

[0600] The LR-UE sets the SRS according to the setting of its own SRS notified by the eNB, and transmits the SRS using the corresponding uplink time slot according to the SRS transmission request notified by the eNB.

[0601] Thereby, it is not necessary to notify at least one of the PUSCH region information of other LR-UEs and the region information with no mapping, and thus the amount of DCI information can be reduced.

[0602] Alternatively, it is possible to notify only the SRS setting information without notifying the SRS transmission request. The setting of the SRS can be predetermined as the SRS transmission request. The LR-UE transmits the SRS using the corresponding uplink time slot according to the setting of its own SRS notified by the eNB. Thereby, the amount of DCI information can be further reduced.

[0603] By using the above method, the LR-UE can cope with the flexible scheduling of the PUSCH of legacy UEs. The LR-UE can avoid the PRBs mapped with the PUSCH of legacy UEs to transmit the SRS.

[0604] Moreover, it can flexibly cope with the load conditions and radio wave transmission conditions that change over time, and thus can suppress the decrease in the usage efficiency of physical resources.

[0605] In odd-numbered time slots, as another method, the SRS for the LR-UE can be formed in the last symbol within the time slot, and multiplexed with the SRS of the traditional UE using the above method.

[0606] The eNB notifies the traditional UE of the SRS structure of the traditional UE. Therefore, the traditional UE can identify in which time slot the last symbol has an SRS formed, and does not use this symbol to transmit data. By using this symbol that does not transmit data as the SRS of the LR-UE, data conflicts with the traditional UE can be avoided.

[0607] By using the above method, the SRS of the LR-UE can be transmitted in time slot units. In addition, the SRS of the LR-UE and the SRS of the traditional UE can coexist on the same carrier in LTE.

[0608] Therefore, the eNB can receive the SRS of the LR-UE in time slot units, and can use this SRS to perform efficient data scheduling for the LR-UE.

[0609] In addition, a decrease in the efficiency of the eNB's data scheduling for the traditional UE can be suppressed, while the efficiency of data scheduling for the LR-UE can be improved.

[0610] Therefore, a decrease in the data transmission speed of the traditional UE can be suppressed, and the data transmission speed of the LR-UE can be increased.

[0611] Sometimes, the SRS setting of the LR-UE and the transmission of the PUCCH occur in the same time slot. In this case, the same method as when the existing SRS and PUCCH occur simultaneously can be adopted. By adopting the same method as the existing method, the complexity of control can be avoided.

[0612] As described above, in this embodiment, an SRS in time slot units is disclosed to cope with the shortened TTI.

[0613] However, as another method, for the transmission of the SRS of the LR-UE, the existing SRS transmission method in subframe units can also be applied.

[0614] In the eNB's scheduling, there are sometimes cases where an SRS in time slot units is not required. For example, when the cell load is low, etc. Even without an SRS in time slot units, the decrease in the eNB's scheduling efficiency is small. In the above cases, by applying the existing SRS transmission method, an increase in the signaling volume can be suppressed. In addition, coexistence with the traditional UE becomes easier, so the complexity of control can be avoided.

[0615] The SRS in time slot units and the SRS in subframe units can be appropriately combined. It can be used separately for each cell or for each UE. It can be used separately in a quasi-static or dynamic manner. It can be used separately according to the load of the cell as a judgment criterion, the throughput of the cell, the average delay time of the cell, the communication quality of each UE, each requested QoS (Quality of Service), each requested delay time, etc.

[0616] Use the PUCCH for LR-UE to send Ack / Nack for SR, CSI, and downlink data. However, when sending the PUCCH and SRS of this LR-UE in the same symbol, the same method as that of the PUCCH and SRS of existing traditional UEs can be adopted.

[0617] Embodiment 6.

[0618] In Embodiment 1, as an example of the shortened TTI, the case of TTI = 1 time slot was disclosed. In this embodiment, as an example of the shortened TTI, for the case of TTI = 1 symbol, a solution is disclosed.

[0619] For the transmission methods of PDSCH and PDCCH, the following two types (1) and (2) are disclosed.

[0620] (1) Use RRC signaling to set the physical resource area for mapping the PDCCH of the LR-UE for the UE.

[0621] (2) Use RRC signaling to set the physical resource area for mapping the PDSCH of the LR-UE for the UE.

[0622] In the above transmission method (1), the scheduling information of the PDSCH of the LR-UE is included in the PDCCH of the LR-UE. The LR-UE receives the PDCCH sent to itself, receives the scheduling information of the PDSCH sent to itself included in the received PDCCH, and receives the PDSCH.

[0623] For the above transmission method (1), a specific example is further disclosed. As the physical resource mapped with the PDCCH of the LR-UE, it is composed of PRB units. As the physical resource mapped with the PDCCH of the LR-UE, it can also be composed of PRB pairs.

[0624] Map the PDCCH of the LR-UE to the physical resource area mapped with the existing PDSCH.

[0625] The PDCCH of the LR-UE is mapped while avoiding the PRB pairs mapped with the PDSCH of the traditional UE.

[0626] The symbols (symbols 1 to 4, indicated by PCFICH) of the existing PDCCH are excluded from the mapping.

[0627] By using the above method, the PDCCH region of the LR-UE can coexist with the existing physical channels. Here, the PDCCH region of the LR-UE is referred to as the "LR-PDCCH region".

[0628] Within the LR-PDCCH region, the PDCCHs of multiple LR-UEs are multiplexed. The PDCCH of any one LR-UE is mapped within 1 symbol. The PDCCHs of multiple LR-UEs within 1 symbol can be multiplexed. Or, the PDCCH of one LR-UE can be mapped to 1 symbol, and the PDCCHs of multiple LR-UEs within the LR-PDCCH region are multiplexed.

[0629] The DCI of the LR-UE can be used as the DCI with each TTI = 1 symbol. The DCI contains scheduling information for 1 symbol.

[0630] The DCI of the LR-UE can also contain the scheduling information of the PDSCH of the LR-UE. The scheduling information of the LR-UE can also contain the allocation information for allocating the PDSCH of the LR-UE to physical resources. The DCI of the LR-UE is mapped to the PDCCH of the LR-UE and is mapped to the LR-PDCCH region.

[0631] As the scheduling information, there is allocation information, MCS information, etc. As the allocation information, there is symbol information, subcarrier information. In order to determine the physical resources on the frequency axis, the PRB information can also be used as the information in units of PRBs to replace the subcarrier information. For example, the number of PRBs, the PRB number, etc.

[0632] The CRC obtained by scrambling with the C-RNTI of the LR-UE can also be used for the PDCCH for the LR-UE. Similar to the existing PDCCH for UEs, the LR-PDCCH region can be retrieved using the C-RNTI of the LR-UE itself, so that the PDCCH sent to itself can be detected and received.

[0633] The PDCCH containing the scheduling information of the PDSCH of the LR-UE can be mapped to the same symbol in the LR-PDCCH region as the PDSCH.

[0634] Thus, the LR-UE detects its own PDCCH and can receive the PDSCH in the same symbol as the received symbol.

[0635] In addition, multiple PDCCHs of the LR-UE can be mapped to multiple symbols in the LR-PDCCH region.

[0636] The LR-UE detects and receives its own PDCCH within the LR-PDCCH region on a per-symbol basis. According to the scheduling information of the received PDCCH, it receives the PDSCH present in the same symbol as the PDCCH.

[0637] In addition, multiple PDCCHs of the LR-UE can be mapped within 1 symbol. Different PDSCHs are scheduled. Each PDSCH can be mapped within the same symbol or to different symbols.

[0638] In the case of mapping within the same symbol, the LR-UE detects and receives its own PDCCH within the LR-PDCCH region on a per-symbol basis. According to the scheduling information contained in the multiple received PDCCHs, it receives multiple PDSCHs present in the same symbol as the PDCCH.

[0639] In the case of mapping to different symbols, information for determining the symbol can be set in the DCI. This is effective not only when the PDSCH is scheduled to the same symbol but also when the PDSCH is scheduled to other symbols. The LR-UE detects and receives its own PDCCH within the LR-PDCCH region on a per-symbol basis. According to the scheduling information contained in the multiple received PDCCHs, it receives the PDSCH using the symbol that schedules the PDSCH.

[0640] In addition, the scheduling information of multiple PDSCHs can be mapped to the DCI of one PDCCH of the LR-UE. Each PDSCH can be mapped within the same symbol or to different symbols. Information for determining the symbol to which each PDSCH is mapped can be set in the DCI. The LR-UE detects and receives its own PDCCH within the LR-PDCCH region on a per-symbol basis. According to the scheduling information of the multiple PDSCHs contained in the received PDCCH, it receives multiple PDSCHs.

[0641] Figure 31 It is a diagram for explaining the transmission method of PDCCH and PDSCH for each symbol of the LR-UE in Embodiment 6. In Figure 31 In the example shown, the LR-PDCCH region is configured in PRB units for each time slot. The LR-PDCCH region and the region where the PDSCH of the legacy UE is mapped are configured not to overlap. In the case of first configuring the LR-PDCCH region, the PDSCH of the legacy UE is mapped avoiding the LR-PDCCH region. Within the LR-PDCCH region, the PDCCHs of multiple LR-UEs are multiplexed and mapped on a per-symbol basis. The PDCCH of the same LR-UE can be mapped multiple times. The symbols of the existing PDCCH region 160 are excluded from the LR-PDCCH region in the first time slot within the subframe.

[0642] The PDSCH of the LR-UE is scheduled by using the PDCCH of the LR-UE mapped within the LR-PDCCH region. The PDSCH within the symbol identical to the symbol where the PDCCH of the LR-UE exists is scheduled. The PDSCH of the LR-UE and the PDSCH of the legacy UE are scheduled in a non-overlapping manner. Thus, coexistence with the legacy UE is enabled.

[0643] In Figure 31 In the example shown, the PDSCH of the LR-UE is scheduled to the same frequency region on the frequency axis. Not limited thereto, the PDSCH of the LR-UE may also be individually scheduled to different frequency regions on the frequency axis. In the case of scheduling in the same frequency region on the frequency axis, for example, the frequency region of the PRB, i.e., in units of 12 subcarriers, scheduling can be easily and efficiently performed by using the relationship of the mapping of the PDSCH of the legacy UE to the physical resources. As shown by reference numeral "161", there are physical resources that are not scheduled in symbol units.

[0644] Figure 32 is a diagram for explaining another example of the PDCCH and PDSCH of each symbol of the LR-UE in Embodiment 6. Figure 32 Shows the case where the frequencies of the PRB pairs of the PDSCH of the legacy UE are different. The LR-PDCCH is configured in different frequency regions on the frequency axis for each time slot. Further, in the second time slot within the subframe, the PDSCH is continuously scheduled with the PDCCH of the LR-UE mapped within the LR-PDCCH region. The symbols of the existing PDCCH region 165 are excluded from the LR-PDCCH region in the first time slot within the subframe.

[0645] Thus, by flexibly configuring the LR-PDCCH region in units of PRBs for each time slot, the physical resources to which the PDSCH of the legacy UE and the PDSCH of the LR-UE are mapped can be flexibly set.

[0646] A method for setting the LR-PDCCH region is disclosed. The LR-PDCCH region is set. It is also possible to set it as an LR-PDCCH set. The resources on the frequency axis of the LR-PDCCH set are set in units of PRBs. Continuous PRBs can be set, or discontinuous PRBs can be set.

[0647] The resources on the time axis of the LR-PDCCH region are set in units of time slots. Continuous time slots can be set, or discontinuous time slots can be set. It can be set for each time slot. Or, it can be set in units of subframes.

[0648] The LR-PDCCH region can be set for each cell, or for each LR-UE, or for each group of LR-UEs, such as for each group of LR-UEs mapped to the LR-PDCCH region. In addition, it can be set by the standard for the system. Or, it can be a combination of them.

[0649] For example, the settings on the time axis and frequency axis of the LR-PDCCH region are per cell. The multiplexing method of LR-UEs within 1 symbol can be determined by the standard in advance for the system. Thus, the eNB can preset the slot timing and PRB of the LR-PDCCH region, making scheduling easier. The LR-UE can identify the slot timing and PRB of the LR-PDCCH region set for each cell, retrieve the PDCCH for each UE in that slot and PRB, and receive it.

[0650] As another example, the setting of the resources for the LR-PDCCH region can be performed per cell. In fact, the setting of the LR-PDCCH region for LR-UEs can be performed per UE. By presetting the resources for the LR-PDCCH region per cell in advance, it becomes easier to schedule the PDCCH of LR-UEs on the same subframe as traditional UEs. In addition, it becomes easier for traditional UEs and LR-UEs to coexist.

[0651] The setting of the LR-PDCCH region can be determined statically, or quasi-statically or dynamically.

[0652] In the case of static determination, it can be determined by the standard or the like. In the case of quasi-static or dynamic determination, RRC signaling can be used.

[0653] For example, the per-cell setting is determined in advance using the standard, and the per-UE setting can be determined quasi-statically or dynamically using RRC signaling.

[0654] As another example, in the case of per-cell setting, as broadcast information, it can be broadcast by the eNB to the UEs within the coverage area. In the case of per-LR-UE setting, using UE-specific signaling, the eNB notifies the LR-UEs that perform shortened TTIs.

[0655] The eNB can include the setting information of the LR-PDCCH region in the RRC Connection Reconfiguration message and notify the LR-UE as RRC signaling.

[0656] Disclose the actions of the LR-UE. The LR-UE receives the PCFICH and identifies the symbol where the PDSCH region of slot #0 starts. The LR-UE detects the LR-PDCCH region using its own C-RNTI. The structure of the LR-PDCCH region is notified by the eNB using RRC signaling, for example.

[0657] Thereby, the LR-UE can detect the PDCCH sent to itself. The LR-UE obtains the DCI from the PDCCH detected by its own C-RNTI. The LR-UE receives the PDSCH using the scheduling information in the DCI. To identify which symbol and which subcarrier the PDSCH is allocated to, symbol information and subcarrier information can be used. To determine the frequency region within the symbol, PRB information can be used as information in units of PRB. The LR-UE demodulates the received PDSCH using the scheduling information and obtains the data.

[0658] In the LR-PDCCH region, RS is set for each symbol. RS is set for the symbol where the PDCCH of the LR-UE is mapped. It can be used for the demodulation of the PDCCH. In addition, RS can be set within the physical resources of the symbol where the PDSCH of the LR-UE is mapped. It can be used for the demodulation of the LR-PDSCH. The RS can be set separately for each cell or separately for each LR-UE.

[0659] When the PDCCH or PDSCH of the LR-UE is mapped to multiple consecutive PRBs on the frequency axis, the subcarrier spacing for setting RS can be increased. For example, the number of PRBs and the subcarrier spacing for setting RS can be determined in advance according to the standard. Alternatively, the eNB determines it quasi-statically or dynamically and notifies the LR-UE using RRC signaling.

[0660] In addition, by mapping the PDCCH and PDSCH of the LR-UE to consecutive PRBs on the frequency axis, the demodulation can be performed using the RS after combining the PDCCH and PDSCH. Therefore, in the above case, the subcarrier spacing for setting RS can be increased. In the above case, the number of consecutive PRBs and the subcarrier spacing for setting RS can also be determined in advance according to the standard. Alternatively, the eNB determines it quasi-statically or dynamically and notifies the LR-UE using RRC signaling.

[0661] In addition, by mapping the PDCCH and PDSCH of the LR-UE to consecutive symbols on the time axis, the RS after combining the PDCCH and PDSCH can be used for demodulation. Therefore, in the above case, the interval between the symbols where the RS is set can be increased. In the above case, the number of consecutive symbols and the interval between the symbols where the RS is set can also be determined in advance according to the standard. Alternatively, the eNB determines them quasi-statically or dynamically and notifies the LR-UE using RRC signaling.

[0662] As described above, according to the transmission method (1), the PDSCH of the conventional UE is mapped to physical resources in subframe units. The PDSCH of the LR-UE is mapped to the area of the physical resources where the PDSCH of the conventional UE is mapped in symbol units. Thus, the PDSCH of the LR-UE can be mapped to physical resources for each TTI. Therefore, the transmission speed of data for the LR-UE can be improved. In addition, the PDSCH of the conventional UE and the PDSCH of the LR-UE can coexist in the physical resources within one subframe. Therefore, various TTIs can be accommodated, and a communication system with backward compatibility can be implemented.

[0663] In the case of the transmission method (2), the PDCCH of the LR-UE can be reused in the PDSCH area of the LR-UE, or can be set in other areas. In the case of being set in other areas, the transmission method (1) can be applied. The DCI containing the scheduling information of the PDSCH can be mapped to the PDCCH of the LR-UE. As the scheduling information of the PDSCH of the LR-UE, it may not include the physical resource allocation information of the PDSCH, but only include other information such as MCS. The LR-UE receives the PDCCH sent to itself, receives the scheduling information of the PDSCH contained therein, and receives the PDSCH within the PDSCH area of the LR-UE.

[0664] The physical resources where the PDSCH of the LR-UE is mapped are composed of PRB units. The physical resources where the PDSCH of the LR-UE is mapped can also be composed of PRB pair units.

[0665] Map the PDSCH of the LR-UE to the area of the physical resources where the existing PDSCH is mapped.

[0666] The PDSCH of the LR-UE is mapped while avoiding the PRB pairs where the PDSCH of the conventional UE is mapped.

[0667] The symbols (symbols 1 to 4, indicated by the PCFICH) where the existing PDCCH is mapped are excluded.

[0668] By using the above method, the PDSCH region of the LR-UE can coexist with existing physical channels. Here, the PDSCH region of the LR-UE is referred to as the "LR-PDSCH region".

[0669] Within the LR-PDSCH region, the PDSCHs of multiple LR-UEs are multiplexed. The PDSCH of any one LR-UE is mapped within 1 symbol. The PDSCHs of multiple LR-UEs within 1 symbol can be multiplexed. Alternatively, the PDSCH of one LR-UE can be mapped to 1 symbol, and the PDSCHs of multiple LR-UEs within the LR-PDSCH region are multiplexed.

[0670] The DCI of the LR-UE can be used as the DCI for each TTI = 1 symbol. The DCI contains scheduling information for 1 symbol.

[0671] The DCI of the LR-UE can also contain scheduling information for the PDSCH of the LR-UE. The DCI of the LR-UE is mapped to the PDCCH of the LR-UE and is multiplexed and mapped to the LR-PDSCH region.

[0672] As scheduling information, it has allocation information, MCS information, etc. As allocation information, it has information on physical resources in units of PRBs for determining the frequency region. For example, the number of PRBs, PRB numbers, etc. The scheduling information may not include allocation information for allocating the PDSCH of the LR-UE to physical resources. Since the PDSCH is allocated within the LR-PDSCH region, there may also be no allocation information for allocating the PDSCH of the LR-UE to physical resources.

[0673] The CRC obtained by scrambling with the C-RNTI of the LR-UE can also be used for the PDCCH for the LR-UE. Similar to the existing PDCCH for UEs, the LR-PDSCH region can be retrieved using the C-RNTI of the LR-UE itself, so that the PDCCH sent to itself can be detected and received.

[0674] The PDCCH of the LR-UE can be mapped to the same symbol as the PDSCH within the LR-PDSCH region. The PDCCH of the LR-UE is multiplexed and mapped with the PDSCH. The multiplexing is performed within 1 symbol. As multiplexing methods, for example, there are frequency division multiplexing, code division multiplexing, etc. In the case of using frequency division multiplexing, it can be divided and multiplexed in units of subcarriers and REs. In addition, on the frequency axis, it is divided and multiplexed in units of PRBs (12 subcarrier units). It can be applied to the case where the LR-PDSCH region is composed of multiple PRBs.

[0675] The multiplexing method can be determined statically in advance according to standards or the like, or can be determined quasi-statically or dynamically. In the case of quasi-static or dynamic determination, it can be determined by the eNB and notified to the LR-UE using RRC signaling. In addition, a list of several multiplexing methods can be set in advance according to standards, and information indicating which one of them is selected can be set and notified to the LR-UE.

[0676] Thereby, the LR-UE detects its own PDCCH and can receive the PDSCH in the same symbol as the received symbol.

[0677] In addition, multiple PDCCHs of the LR-UE can be multiplexed into multiple symbols in the LR-PDSCH region.

[0678] The LR-UE detects and receives its own PDCCH in the LR-PDSCH region per symbol. According to the scheduling information of the received PDCCH, it receives the PDSCH present in the same symbol as the PDCCH.

[0679] In addition, multiple PDCCHs of the LR-UE can be mapped within one symbol. Different PDSCHs are scheduled. Each PDSCH can be mapped within the same symbol or to different symbols.

[0680] In the case of being mapped within the same symbol, the LR-UE detects and receives its own PDCCH multiplexed in the LR-PDSCH region per symbol. According to the scheduling information included in the multiple received PDCCHs, it receives multiple PDSCHs present in the same symbol as the PDCCH.

[0681] In the case of being mapped to different symbols, information for determining the symbol can be set in the DCI. This is effective not only when the PDSCH is scheduled to the same symbol but also when the PDSCH is scheduled to other symbols. The LR-UE detects and receives its own PDCCH in the LR-PDSCH region per symbol. According to the scheduling information included in the multiple received PDCCHs, it receives the PDSCH using the symbol that schedules the PDSCH.

[0682] In addition, the scheduling information of multiple PDSCHs can be mapped to the DCI of one PDCCH of the LR-UE. Each PDSCH can be mapped within the same symbol or to different symbols. Information for determining the symbol to which each PDSCH is mapped can be set in the DCI. The LR-UE detects and receives its own PDCCH in the LR-PDSCH region per symbol. According to the scheduling information of the multiple PDSCHs included in the received PDCCH, it receives multiple PDSCHs.

[0683] Figure 33This is a diagram for explaining the transmission method of Embodiment 6. Figure 33 The transmission method of the PDSCH when forming the LR-PDSCH is described.

[0684] In Figure 33 In the example shown, the LR-PDSCH region is formed in units of PRBs per time slot. The region where the LR-PDSCH region and the PDSCH of the legacy UE are mapped is configured not to overlap. When the LR-PDSCH region is formed first, the PDSCH of the legacy UE is mapped avoiding the LR-PDSCH region. When scheduling is performed in the same frequency region on the frequency axis, for example, in a frequency region of PRBs, i.e., in units of 12 subcarriers, the LR-PDSCH region can be scheduled simply and efficiently using the relationship with the mapping of the PDSCH of the legacy UE to physical resources.

[0685] Within the LR-PDSCH region, the PDSCHs of multiple LR-UEs are multiplexed and mapped per symbol. The PDSCH of the same LR-UE can be mapped multiple times. The symbols of the existing PDCCH region are excluded from the LR-PDSCH region in the first time slot within the subframe.

[0686] The PDCCH of the LR-UE can be multiplexed within the LR-PDSCH region. The PDSCH of the LR-UE is scheduled using this PDCCH. The PDSCH within the same symbol as the symbol where the PDCCH of the LR-UE exists is scheduled. As shown by reference numeral "170", there are physical resources that are not scheduled in units of symbols.

[0687] Figure 34 This is a diagram for explaining another method of forming the LR-PDSCH of Embodiment 6.

[0688] In Figure 33 In the example shown, the LR-PDSCH region is formed in the same frequency region on the frequency axis in the first and second time slots within the subframe. Not limited to this, the LR-PDSCH can also be formed separately in different frequency regions on the frequency axis.

[0689] Figure 34 The case where the LR-PDSCH region is formed separately in different frequency regions on the frequency axis per time slot is shown. By flexibly forming the LR-PDSCH on the frequency axis, the physical resources where the PDSCH of the legacy UE is mapped can be set flexibly.

[0690] The setting method of the LR-PDSCH can also apply the setting method of the LR-PDCCH of the above-described transmission method (1).

[0691] Disclose the actions of the LR-UE. The LR-UE receives the PCFICH and identifies the symbol where the PDSCH region of slot #0 starts.

[0692] In the LR-PDSCH region, the LR-UE detects the PDCCH sent to itself using its own C-RNTI. The structure of the LR-PDSCH region is notified by the eNB using RRC signaling, for example. The multiplexing method of the PDSCH and PDCCH in the LR-PDSCH region is predetermined by the standard, for example. Thus, the LR-UE can detect the PDCCH sent to itself.

[0693] The LR-UE obtains the DCI from the PDCCH detected by its own C-RNTI. The LR-UE obtains the scheduling information in the DCI. The LR-UE receives the PDSCH using the above multiplexing method and scheduling information, demodulates it, and obtains the data.

[0694] In the LR-PDSCH region, RS is set for each symbol. It can be used for demodulation of the PDCCH and LR-PDCCH of the LR-UE. The RS can be set separately for each cell or separately for each LR-UE.

[0695] As a method for constructing the RS of the PDSCH region of the LR-UE, the method for constructing the RS of the PDCCH region of the LR-UE disclosed in the above-mentioned transmission method (1), the method for constructing the RS when mapping the PDCCH and PDSCH of the LR-UE to consecutive PRBs on the frequency axis, and the method for constructing the RS when mapping the PDCCH and PDSCH of the LR-UE to consecutive symbols on the time axis can be appropriately applied.

[0696] The PDCCH of the LR-UE can also be set in other regions different from the PDSCH region of the LR-UE. In the case of being set in other regions, the method for setting the LR-PDCCH region in the above-mentioned transmission method (1) can be applied.

[0697] Disclose HARQ. HARQ is performed in units of TTI. For the LR-UE, it can be performed in units of shortened TTI, that is, symbol units in this embodiment. In addition, for traditional UEs, it is performed in existing TTI, that is, subframe units. For the LR-UE, the method for performing HARQ in units of shortened TTI can apply the method disclosed in Variation 1 of Embodiment 1. Asynchronous HARQ can also be applied. Similar to the existing PDCCH region, there are symbols where the PDSCH of the LR-UE cannot be mapped. In the above cases, by using asynchronous HARQ, scheduling other than the existing PDCCH region can be performed.

[0698] By using the method disclosed in this embodiment, the PDSCH of the LR-UE can be mapped to physical resources per TTI. The PDSCH of the LR-UE can be mapped to physical resources per symbol. In addition, the PDSCH of the traditional UE and the PDSCH of the LR-UE can coexist in the physical resources within one subframe. Scheduling of the PDSCH of the LR-UE with a TTI shorter than one subframe can be performed. Therefore, the transmission speed of data for the LR-UE can be increased. In addition, the LR-UE and the traditional UE can coexist on the same carrier in LTE.

[0699] Embodiment 7.

[0700] Disclose the Ack / Nack for uplink data. As described in Embodiment 2, since the TTI is shorter than one subframe, the LR-UE needs to perform HARQ in units shorter than one subframe. However, in the case of performing HARQ in units shorter than one subframe, the existing LTE PHICH transmission method cannot be applied. In addition, in order to support the shortened TTI on the same carrier in LTE, it is necessary to strive to achieve the coexistence of the LR-UE and the traditional UE. In this embodiment, a method for solving the above problems is disclosed.

[0701] For the LR-UE, HARQ is performed in TTI units. It is assumed that the Ack / Nack for the uplink data of the LR-UE can be sent in symbol units.

[0702] As a specific example of the Ack / Nack transmission method, four types of (1) to (4) below are disclosed.

[0703] (1) Transmit using LR-PHICH.

[0704] (2) Multiplex and transmit in the LR-PDCCH region.

[0705] (3) Transmit using the PDCCH of the LR-UE.

[0706] (4) A combination of (1) to (3) above.

[0707] Disclose the method of transmitting using the LR-PHICH of the specific example (1). Set up a physical channel, namely PHICH, for transmitting the Ack / Nack for the uplink data of the LR-UE. Hereinafter, this PHICH will be referred to as "LR-PHICH". Map the LR-PHICH within 1 symbol.

[0708] Apply the LR-PHICH structure disclosed in Embodiment 2 to this LR-PHICH structure. In Embodiment 2, the Ack / Nack of the LR-UE is mapped to the entire physical resource for the LR-PHICH, while in this embodiment, the Ack / Nack of the LR-UE is mapped within 1 symbol of the physical resource for the LR-PHICH. The LR-PHICH group can also be mapped within 1 symbol of the physical resource for the LR-PHICH. In addition, one HREG can be constituted within 1 symbol. Thus, the Ack / Nack of any LR-UE is sent within 1 symbol of the physical resource for the LR-PHICH.

[0709] Thus, the Ack / Nack for the uplink data of the LR-UE can be sent in symbol units.

[0710] Disclose a method for multiplexing and transmitting the LR-PDCCH region for the specific example (2). The Ack / Nack for the LR-UE is multiplexed and mapped to the physical resource where the LR-PDCCH is mapped. The PHICH for the LR-UE and the PDCCH for the LR-UE are multiplexed within 1 symbol of the LR-PDCCH region.

[0711] As multiplexing methods, for example, there are frequency division multiplexing and code division multiplexing. In the case of using frequency division multiplexing, division multiplexing can be performed in subcarrier units and RE units.

[0712] The multiplexing method can be determined statically in advance according to standards, etc., or can be determined quasi-statically or dynamically. In the case of quasi-static or dynamic determination, it can be determined by the eNB and notified to the LR-UE using RRC signaling. In addition, a list of several multiplexing methods can be set in advance according to standards, and information indicating which one of them is selected can be set and notified to the LR-UE.

[0713] As a multiplexing method, the method for multiplexing and transmitting the LR-EPDCCH region disclosed in Embodiment 2 can be applied. In Embodiment 2, the Ack / Nack of the LR-UE is mapped to the entire PRB of the LR-EPDCCH region, while in this embodiment, the Ack / Nack of the LR-UE is mapped within 1 symbol of the LR-PDCCH region. The LR-PHICH group can be mapped within 1 symbol of the LR-PDCCH region. In addition, one HREG can be constituted within 1 symbol. Thus, the Ack / Nack of any LR-UE is multiplexed and sent within 1 symbol of the physical resource for the PDCCH of the LR-UE.

[0714] Disclosed is a method for transmitting using the PDCCH of the LR-UE of the specific example (3). The transmission of the Ack / Nack for the uplink data of the LR-UE is performed only through scheduling in the PDCCH of the LR-UE. The PHICH of the LR-UE may not be provided either.

[0715] The DCI for the LR-UE contains information indicating whether it is new data. The DCI is mapped to the PDCCH of the LR-UE. The LR-UE receives this information in the DCI by receiving the PDCCH addressed to itself, and thus can identify whether the scheduling is for new data or for retransmitted data. When this information indicates new data, the LR-UE transmits new data according to this scheduling. In this case, the LR-UE can be regarded as an Ack. When this information indicates not new data, the LR-UE transmits retransmitted data according to this scheduling. In this case, the LR-UE can be regarded as a Nack.

[0716] Thus, the LR-PHICH may not be provided, and the area for the LR-PHICH may not be provided either. Therefore, the physical resources for data can be increased, and an attempt can be further made to improve the data transmission speed.

[0717] Thus, the Ack / Nack for the uplink data of the LR-UE can be transmitted, and the HARQ for the uplink data can be performed in units of the shortened TTI. The HARQ for the uplink data can be performed in units of symbols.

[0718] Therefore, it is possible to reduce the delay time and improve the data transmission speed.

[0719] In addition, the LR-UE and the traditional UE can coexist on the same carrier of LTE.

[0720] Embodiment 8.

[0721] The PUSCH is disclosed. As described in Embodiment 3, for the LR-UE operating with the shortened TTI, since 1 TTI is shorter than 1 subframe, when mapping its PUSCH to physical resources, the mapping method of the traditional UE cannot be applied. In addition, in order to support the shortened TTI on the same carrier of LTE, an attempt has to be made to achieve the coexistence of the LR-UE and the traditional UE. In this embodiment, a method for solving the above problems is disclosed.

[0722] For the transmission method of the PUSCH, the following two types (1) and (2) are disclosed.

[0723] (1) The scheduling information of the PUSCH of the LR-UE is notified to the UE by using the PDCCH of the LR-UE.

[0724] (2) Use RRC signaling to notify the UE of the scheduling information of the PUSCH of the LR-UE.

[0725] In the sending method (1), the LR-UE receives the scheduling information of the PUSCH of the LR-UE included in the PDCCH by receiving the PDCCH with the LR-UE, thereby receiving the PUSCH.

[0726] In the sending method (2), the LR-UE uses the scheduling information of the PUSCH of the LR-UE notified by the eNB using RRC signaling to receive the PUSCH.

[0727] For the sending method (1), a specific example is further disclosed. As the physical resource mapped with the PUSCH of the LR-UE, it is composed of symbol units.

[0728] The physical resource mapped with the PUSCH of the LR-UE is composed of one or more predetermined frequencies within one symbol. As the predetermined frequency, it can be set to subcarrier unit or RE unit. For example, 12 subcarriers within one symbol can be set as the physical resource mapped with the PUSCH of the LR-UE.

[0729] Map the PUSCH of the LR-UE to the physical resource area mapped with the existing PUSCH.

[0730] The PUSCH of the LR-UE is mapped avoiding the PRB pair mapped with the PUSCH of the traditional UE.

[0731] By using the above method, the PUSCH of the LR-UE can coexist with the existing physical channels.

[0732] Figure 35 It is a diagram for explaining the sending method of the PUSCH of each symbol of the LR-UE in Embodiment 8. The PUSCH of the LR-UE is mapped to the physical resource per symbol. In Figure 35 In the shown example, it is mapped to the physical resource in units of 12 subcarriers. In subframe #1, the PUSCH of the LR-UE is mapped to the physical resource of 12 subcarriers within one symbol. In subframe #2, the PUSCH of the LR-UE is mapped to the physical resource of two consecutive 12 subcarriers within one symbol. Thus, the data volume can be increased. The scheduling of the PUSCH of the LR-UE uses the downlink PDCCH.

[0733] In Figure 35In the example shown, the PUSCH of the LR-UE is scheduled to the same frequency region on the frequency axis per time slot. Without being limited thereto, the PUSCH of the LR-UE may also be individually scheduled to different frequency regions on the frequency axis. In the case of scheduling in the same frequency region on the frequency axis, for example, in the frequency region of PRB, i.e., 12 sub-carrier units, scheduling can be easily and efficiently performed by using the relationship of the mapping of the PUSCH of the conventional UE to the physical resources. As shown by the reference numeral "171", there are physical resources that are not scheduled in symbol units.

[0734] Since the symbols of the existing PDCCH region are not mapped with the PDCCH for the LR-UE, it is impossible to schedule the PUSCH for each symbol. In the uplink symbols corresponding to the symbols of the existing PDCCH region, the PUSCH may not be transmitted.

[0735] Alternatively, as another method, the PDCCH for the LR-UE may be used to schedule the uplink symbols corresponding to the symbols of the existing PDCCH region. Thereby, even in the uplink symbols corresponding to the symbols of the existing PDCCH region, the PUSCH can be transmitted.

[0736] Alternatively, as another method, the PDCCH for the LR-UE may be multiplexed and mapped to the symbols of the existing PDCCH region. Thereby, even in the uplink symbols corresponding to the symbols of the existing PDCCH region, the PUSCH can be transmitted.

[0737] The PUSCH of any one LR-UE is mapped within 1 symbol. The PUSCHs of multiple LR-UEs within 1 symbol may be multiplexed.

[0738] The PUSCH of any one LR-UE may be mapped to consecutive sub-carriers or REs. Alternatively, it may be mapped to non-consecutive sub-carriers or REs. In the non-consecutive case, it is mapped to equally spaced sub-carriers or REs. It can also be applied to SC-FDMA.

[0739] In the case of mapping to equally spaced sub-carriers or REs, it is only necessary to stagger and map the sub-carriers or REs of the PUSCHs of multiple LR-UEs one by one. Thereby, even in the case of using non-consecutive sub-carriers or REs, the PUSCHs of multiple LR-UEs can be multiplexed to the physical resources within 1 symbol.

[0740] In the case of mapping to non-consecutive sub-carriers or REs, the physical resources in the frequency axis direction for mapping the PUSCH of the LR-UE are expanded. However, through the expansion of the physical resources in the frequency axis direction, a frequency diversity gain can be obtained.

[0741] Figure 36This is a diagram for explaining the method of multiplexing the PUSCHs of multiple LR-UEs within one symbol and transmitting them. The PUSCH of the LR-UE is mapped to physical resources per symbol. In Figure 36 the example shown, it is mapped to physical resources in units of 12 subcarriers.

[0742] In the third symbol of the first time slot within a subframe, the PUSCHs of two LR-UEs are multiplexed. The PUSCH of each LR-UE is mapped to physical resources of 12 consecutive subcarriers. The PUSCHs of the two LR-UEs are also multiplexed in the fifth symbol in the same way. In the seventh symbol, the PUSCH of one LR-UE is mapped to physical resources of two consecutive 12-subcarrier.

[0743] In the first symbol of the second time slot within a subframe, the PUSCHs of two LR-UEs are multiplexed. The PUSCH of each LR-UE is mapped to physical resources of non-consecutive 12 subcarriers. The PUSCHs of the two LR-UEs are also multiplexed in the fourth symbol in the same way.

[0744] Thus, the PUSCHs of multiple LR-UE data can be mapped to physical resources more flexibly.

[0745] In the existing PUSCH, frequency hopping is performed. However, when the PUSCH is mapped within one symbol, frequency hopping cannot be performed.

[0746] To solve this problem, the above method of mapping one LR-UE to equally spaced subcarriers or REs can be used. By expanding the physical resources in the frequency axis direction for mapping the PUSCH of the LR-UE, frequency diversity gain can be obtained.

[0747] As another method, multiple TTIs can be selected for the UE. For example, for a UE with excellent uplink communication quality, set TTI = 1 symbol. For a UE with poor uplink communication quality, set TTI = 1 time slot or 1 subframe.

[0748] For a UE with excellent communication quality and no need for frequency diversity gain, select TTI = 1 symbol that does not support frequency hopping and set it. For a UE with poor communication quality and in need of frequency diversity gain, select TTI = 1 time slot or 1 subframe that supports frequency hopping and set it.

[0749] This selection and setting can be performed by the eNB evaluating the uplink communication quality between the eNB and the target UE. In addition, the UE can notify the eNB of a request for TTI setting.

[0750] Thus, frequency hopping can be supported adaptively for LR-UEs, and diversity gain can be obtained.

[0751] The DCI of the LR-UE can be used as the DCI for each TTI of 1 symbol. The DCI contains scheduling information for 1 symbol. The DCI of the LR-UE can also contain the scheduling information for the PUSCH of the LR-UE. The DCI of the LR-UE is mapped to the PDCCH of the LR-UE. For the method of constructing the PDCCH of the LR-UE, the method disclosed in Embodiment 7 can be applied.

[0752] The actions of the LR-UE are disclosed. The LR-UE detects the PDCCH sent to itself and obtains the DCI. The method disclosed in Embodiment 7 can be applied to this method. The LR-UE receives the PUSCH using the scheduling information in the DCI. In order to identify which symbol and which frequency region the PDSCH is allocated to, symbol information and frequency region information can be used. The LR-UE demodulates the received PDSCH using the scheduling information and obtains the data.

[0753] In the PUSCH region of the LR-UE, RS is set for each symbol. It can be used for the demodulation of the PUSCH. RS can be set within the period of 1 symbol. It can also be used for the demodulation of the PUSCH. The UE time-division multiplexes the data of the PUSCH with the RS and maps it to the period of 1 symbol. The RS can be inserted into a predetermined position. The predetermined position can be determined statically according to standards, etc. Or, it can be determined quasi-statically or dynamically. The predetermined position can be determined by the eNB and notified to the LR-UE using RRC signaling. The predetermined position is, for example, the position of the RS, the starting position, the interval, the number of RSs, etc.

[0754] As described above, in this embodiment, a case where the PUSCH of the LR-UE is mapped while avoiding the PRB pair where the PUSCH of the legacy UE is mapped is shown.

[0755] As another method, it is possible not to avoid mapping to the PRB pair where the PUSCH of the legacy UE is mapped.

[0756] Figure 37 It is a diagram for explaining the mapping method of Embodiment 8. Figure 37 Herein, a method of mapping the PUSCH of the LR-UE without avoiding the PUSCH of the legacy UE is described. The PUSCH of the LR-UE is mapped to physical resources for each symbol. In Figure 37In the example shown, the PUSCH of LR-UE#1 is mapped to the physical resources of three consecutive 12 sub-carriers at the 5th symbol in the first time slot within the sub-frame. The PUSCH of LR-UE#2 is mapped to the physical resources of two consecutive 12 sub-carriers at the 6th symbol in the first time slot within the sub-frame. The PUSCH of LR-UE#3 is mapped to the physical resources of two consecutive 12 sub-carriers at the 2nd symbol in the second time slot within the sub-frame.

[0757] As Figure 37 shown, during the above mapping, the mapping is performed without avoiding the PRB pair to which the PUSCH of the legacy UE is mapped.

[0758] When mapping the symbol of the PUSCH of the LR-UE, a situation may occur where the PUSCH of the LR-UE conflicts with the PUSCH of the legacy UE. Since it is the uplink, both the PUSCH of the LR-UE and the PUSCH of the legacy UE are transmitted in this symbol. In this case, the eNB may not be able to receive the above channels normally.

[0759] As a method to solve this problem, the transmission power of the LR-UE can be increased to be higher than that of the legacy UE. The eNB sets the transmission power of the LR-UE to be higher than that of the legacy UE. Or, the eNB sets the transmission power of the legacy UE to be lower than that of the LR-UE. The eNB can perform the setting using the power setting parameters notified to the UE.

[0760] As the power setting parameter, the difference from the normal setting value can be set. An offset parameter can be set. The eNB can notify this offset parameter to the LR-UE. Or, the eNB can notify this offset parameter to the legacy UE.

[0761] The eNB can include the power setting parameter in the DCI sent to the legacy UE and the DCI sent to the LR-UE for notification.

[0762] In the case where the legacy UE can only receive the existing power setting parameters, it can also be notified only to the LR-UE.

[0763] The PUSCH transmission power of the UE can be derived using the power setting parameter notified by the eNB to the UE and the path loss measured by the UE. For the transmission powers of the LR-UE and the legacy UE derived using the existing derivation methods, the gap between the transmission powers of the LR-UE and the legacy UE can be further widened. Therefore, the eNB widens the gap between the transmission powers of the LR-UE and the legacy UE, so that the eNB can receive the signal of the higher transmission power side.

[0764] For the PUSCH of a UE with reduced received power, the eNB can reduce the degradation of data reception performance through gains during demodulation such as CRC checking or retransmission control.

[0765] As described above, it is disclosed that the transmission power of an LR-UE can be increased to be higher than that of a conventional UE. Thus, the eNB can receive the signal of the LR-UE. Since the PUSCH of the LR-UE is transmitted in symbol units, when there is a collision with the PUSCH of a conventional UE in this symbol, the gain obtained by demodulating using other symbols cannot be obtained. By enabling the eNB to normally receive the signal of the colliding LR-UE, the reception performance of the PUSCH of the LR-UE can be improved. On the other hand, for the PUSCH of a conventional UE, the gain during demodulation such as CRC checking can be obtained using other symbols, improving the data reception performance.

[0766] Conversely, the transmission power of a conventional UE can also be increased to be higher than that of the LR-UE. The eNB can then receive the signal of the conventional UE, improving the reception performance of the PUSCH of the conventional UE. In this case, although the reception performance of the PUSCH of the LR-UE in the eNB will deteriorate, the degradation can be reduced through retransmission control.

[0767] By using the above method, even when there is a collision between the PUSCH of the LR-UE and the PUSCH of the conventional UE, the eNB can receive their channels.

[0768] Other methods for solving the problems caused by the collision are disclosed. The conventional UE does not transmit in the symbol in which the PUSCH of the LR-UE is transmitted. It can also not transmit data. The transmission power can be set to 0. The conventional UE can also puncture the data of the colliding symbol and transmit using other symbols. The data can be mapped to symbols other than the colliding symbol for transmission.

[0769] Thus, the eNB can receive the PUSCH of the conventional UE.

[0770] The eNB can notify the conventional UE of the symbols used by the LR-UE. The eNB can include the information of this symbol in the DCI sent to the conventional UE for notification. Thus, the conventional UE can identify the symbol in which the LR-UE transmits.

[0771] Conversely, the LR-UE can not transmit in the symbol in which the PUSCH of the conventional UE is transmitted. In this case, the LR-UE can also puncture the RE data of the colliding symbol and transmit using other REs. The data can be mapped to REs other than the colliding RE for transmission.

[0772] Thus, the eNB can receive the PUSCH of the LR-UE.

[0773] The eNB can notify the LR-UE of at least one of the symbols and frequency regions used by the legacy UE. The frequency region is, for example, RE and subcarrier. The eNB can include this power setting parameter in the DCI to the LR-UE for notification. Thereby, the LR-UE can identify at least one of the symbols and frequency regions of the legacy UE transmission.

[0774] For the transmission method (2), a specific example is further disclosed. The eNB notifies the LR-UE of the scheduling information of the LR-UE's PUSCH using RRC signaling. The LR-UE uses the scheduling information of the PUSCH received through RRC signaling to receive its own PUSCH.

[0775] As the scheduling information, it has symbol information, subcarrier or RE information. In addition, when using this scheduling during a predetermined period, information indicating the predetermined period may also be included. The information indicating the predetermined period has information indicating the start time, information indicating the period, information indicating the end time, information indicating the cycle, etc.

[0776] By using the method disclosed in this embodiment, the PUSCH of the LR-UE can be mapped to physical resources for each shortened TTI, here for each symbol. Therefore, the transmission speed of data from the LR-UE can be improved. In addition, the PUSCH of the legacy UE and the PUSCH of the LR-UE can coexist in the physical resources within one subframe.

[0777] Embodiment 9.

[0778] The PUCCH is disclosed. As described in Embodiment 4, for the LR-UE operating with a shortened TTI, since the TTI is shorter than one subframe, when mapping its PUCCH to physical resources, the mapping method of the legacy UE cannot be applied. In addition, in order to support the shortened TTI on the same carrier in LTE, it is necessary to strive for the coexistence of the LR-UE and the legacy UE. In this embodiment, a method for solving the above problems is disclosed.

[0779] The physical resources mapped with the LR-UE's PUCCH are configured in units of PRB. Or the physical resources mapped with the LR-UE's PUCCH are configured in units of PRB pairs. Or the physical resources mapped with the LR-UE's PUCCH are configured in units of symbols.

[0780] The PUCCH for the LR-UE is mapped to the uplink physical resource region. The PUCCH for the LR-UE is mapped avoiding the PRB pairs where the PUCCH of the legacy UE is mapped.

[0781] The PUCCH for the LR-UE can be mapped to the inside of the PRB pair to which the PUCCH of the legacy UE is mapped. The PUCCH for the LR-UE can be mapped continuously with the PRB pair to which the PUCCH of the legacy UE is mapped.

[0782] Similar to the PUCCH of existing legacy UEs, it can be not set on both sides of the frequency axis of the uplink physical resources. That is, it can also be set only on one side of the frequency axis of the uplink physical resources.

[0783] By using the above method, the PUCCH of the LR-UE can coexist with the existing physical channels.

[0784] Here, the physical resources to which the PUCCH for the LR-UE is mapped are referred to as the "LR-PUCCH region".

[0785] The LR-PUCCH region can be set for each cell, or can be set for each LR-UE, or can be set for each group of LR-UEs, for example, for each group of LR-UEs mapped to the LR-PUCCH region. In addition, it can also be set by the system according to standards. Or, it can be a combination of them.

[0786] For example, the settings on the time axis and frequency axis of the LR-PUCCH region are adopted for each cell. The multiplexing method of the LR-UE within 1 symbol can be set by the system in advance according to standards. Thereby, the eNB can preset the LR-PUCCH region, such as the slot timing and PRB, so that scheduling becomes easy. The LR-UE can identify the LR-PUCCH region set for each cell, such as the slot timing and PRB, can search for the PUCCH per UE in the LR-PUCCH region, and receive it.

[0787] As another example, the setting of the resources for the LR-PUCCH region that can be set can be performed for each cell. In fact, the setting of the LR-PUCCH for the LR-UE can also be performed for each UE. By presetting the resources for the LR-PUCCH region that can be set for each cell, the scheduling of the LR-PUCCH on the same subframe as the legacy UE can be made easy. In addition, the coexistence of the legacy UE and the LR-UE can be made easy.

[0788] The setting of the LR-PUCCH region can be determined statically, or can be determined quasi-statically or dynamically.

[0789] In the case of static determination, it can be determined according to standards, etc. In the case of quasi-static or dynamic determination, RRC signaling can be used.

[0790] For example, for the setting per cell, it is pre-determined using a standard, and for the setting per UE, it can be determined quasi-statically or dynamically using RRC signaling.

[0791] As another example, in the case of the setting per cell, as broadcast information, it can be broadcast by the eNB to the UEs within the coverage area. In the case of the setting per LR-UE, using UE-specific signaling, the eNB notifies the LR-UE that performs the shortened TTI.

[0792] The eNB can include the setting information of the LR-PUCCH region in the RRC connection reconfiguration (RRC Connection Reconfiguration) message and notify the LR-UE as RRC signaling.

[0793] Within the LR-PUCCH region, the PUCCHs of multiple LR-UEs are time-division multiplexed for each symbol. Within the LR-PUCCH region, the PUCCHs of multiple LR-UEs can be multiplexed within 1 symbol. Code-division multiplexing can also be adopted. Alternatively, frequency-division multiplexing can also be adopted. In the case of adopting frequency-division multiplexing, the method of multiplexing the PUSCHs of multiple LR-UEs within 1 symbol disclosed in Embodiment 8 can be applied.

[0794] Figure 38 It is a diagram for explaining the mapping of the PUCCH of each symbol of the LR-UE in Embodiment 9 to physical resources. In Figure 38 In the example shown, on one side of the frequency region where the existing PUCCH is mapped, a physical resource region where the LR-PUCCH is mapped is continuously formed inside. The PUCCH of the traditional UE is mapped per time slot. Within the LR-PUCCH region, the PUCCH of the LR-UE is mapped to each symbol. In Figure 38 In the example shown, in the first time slot within the subframe, the PUCCH of the LR-UE is mapped to the 5th and 6th symbols. In the second time slot within the subframe, the PUCCH of the LR-UE is mapped to the 1st, 2nd, 4th, and 6th symbols.

[0795] In the existing PUCCH, frequency hopping is performed. However, in the case of mapping the PUCCH within 1 symbol, frequency hopping cannot be performed. To solve this problem, the method at the time of PUSCH disclosed in Embodiment 8 can be applied. Thus, a frequency diversity gain can be obtained.

[0796] In the PUSCH region of the LR-UE, RS is set for each symbol. It can be used for the demodulation of PUSCH. RS can be set within the period of 1 symbol. It can also be used for the demodulation of PUSCH. The UE time-division multiplexes the data of PUSCH with RS and maps it to the period of 1 symbol. RS can be inserted into a predetermined position. The predetermined position can be determined statically according to standards, etc. Or, it can be determined quasi-statically or dynamically. The predetermined position can be determined by the eNB and notified to the LR-UE using RRC signaling. The predetermined position is, for example, the position of RS such as bits and symbols, the position starting from the beginning, the interval, the number of bits and symbols of RS, etc.

[0797] Thereby, the UCI of each shortened TTI of the LR-UE can be mapped to the PUCCH, and the PUCCH can be mapped to the physical resources for each shortened TTI.

[0798] The PUCCH is also used to send Ack / Nack for the downlink data. Therefore, HARQ for the downlink data in the shortened TTI of the LR-UE can be performed. Therefore, it can reduce the delay time and can increase the data transmission speed.

[0799] Embodiment 10.

[0800] An example of the method for setting SRS is disclosed. SRS in symbol units is set for the LR-UE. It can be set per cell or per UE. Or, a part of the SRS structure can be set per cell, and the remaining part of the SRS structure can be set per UE. The setting of SRS can be performed statically according to standards, etc., or can be performed quasi-statically or dynamically. The eNB notifies the LR-UE of the setting information of SRS in symbol units. RRC signaling or the PDCCH of the LR-UE can be used. When setting per cell, it can be included in the system information for broadcasting. The system information is MIB or SIB. When setting for an individual UE, it can be notified using dedicated RRC signaling. When setting individually for each UE, the information can be included in the DCI and notified to the LR-UE using the PDCCH of the LR-UE.

[0801] When it is necessary for the LR-UE to transmit SRS, the eNB can notify the LR-UE of the SRS transmission request. As the method for notifying the SRS transmission request, the method disclosed in Embodiment 5 can be applied.

[0802] For example, the eNB initially sets the SRS structure per cell. The eNB then sets the SRS structure separately for each LR-UE therein.

[0803] For example, as the SRS structure for each cell, it can be set as the resource information on the time axis. It can be set as the information for determining which symbol constitutes the SRS. As an example of the information for determination, there are system frame number (SFN), radio frame number, time slot number, symbol number, offset value of the radio frame within the system frame, offset value of the time slot within the subframe, offset value of the symbol, and interval between symbols, etc. Thus, the LR-UE can determine the symbols that constitute the SRS in each cell.

[0804] As the SRS structure for each UE, it can be set as the resource information on the frequency axis. It can be set as the information for determining which subcarrier or RE constitutes the SRS. As an example of the information for determination, there are subcarrier number or RE number, etc. The information for determination can also be set as the PRB number.

[0805] In addition, as the SRS structure for each UE, it can be set as the information on the multiplexing method with other LR-UEs or legacy UEs. For example, in the case of frequency division multiplexing with other LR-UEs or legacy UEs within 1 symbol, it is only necessary to set it as the information capable of determining the resources on the frequency axis that constitute its own SRS. As the information capable of determining the resources on the frequency axis, for example, there are offset value of the subcarrier, subcarrier spacing, etc.

[0806] The LR-UE uses the above SRS structure notified by the eNB to map the SRS to the physical resources and transmit it.

[0807] The LR-UE does not use the symbols that constitute the SRS in symbol units to transmit data. It does not map data to this symbol.

[0808] It is possible not to use this symbol to transmit data. As this symbol, it can be only the symbol of the SRS structure set individually for each LR-UE, or only the symbol of the SRS structure set for each cell, or both types of symbols. In addition, it is possible not to map data using this symbol.

[0809] In addition, the LR-UE can refrain from using the symbols that constitute the SRS of the legacy UE to transmit data. It is possible not to map data to this symbol.

[0810] It is also possible not to use this symbol to transmit data. As this symbol, it can be only the symbol of the SRS structure set individually for each legacy UE, or only the symbol of the SRS structure set for each cell, or both types of symbols. In addition, it is possible not to map data using this symbol.

[0811] The eNB can refrain from scheduling the PDSCH for the LR-UE using the symbols that constitute the SRS of the legacy UE.

[0812] The eNB may schedule the PDSCH for the LR-UE without using the symbols that constitute the SRS of the LR-UE.

[0813] The eNB may schedule the PDSCH for other LR-UEs without using the symbols and frequency regions that constitute the SRS of the LR-UE.

[0814] Accordingly, it is possible to avoid a situation where the transmitted data of itself, its own SRS, the SRS of other LR-UEs, or the SRS of a legacy UE conflicts.

[0815] In the case where the SRS is constituted in units of symbols, a conflict may occur with the uplink data of a legacy UE. In this case, as described in Embodiment 5, the communication quality of the uplink data of the legacy UE and the accuracy of the SRS of the LR-UE may deteriorate. As a method for solving the above problems, the method disclosed in Embodiment 5 may be applied.

[0816] Figure 39 is a diagram for explaining a method of configuring the SRS of the LR-UE according to Embodiment 10. In Figure 39 the example shown, the SRS of the LR-UE is constituted for each symbol. The last symbol of the subframe, that is, the last symbol of the second time slot within the subframe, constitutes the SRS of an existing legacy UE. Therefore, in Figure 39 the example shown, the last symbol of the second time slot within the subframe also constitutes the SRS of the LR-UE. The SRS of the legacy UE and the SRS of the LR-UE are multiplexed in this symbol. Accordingly, the SRS of the legacy UE and the SRS of the LR-UE can coexist. The LR-UE can transmit the SRS using the symbols that constitute the SRS.

[0817] The SRS of the LR-UE and the PUSCH of the LR-UE may be multiplexed on the same symbol. The UE time-division multiplexes the data of the PUSCH and the SRS and maps them to a period of 1 symbol. The SRS may be inserted at a predetermined position. The predetermined position may be determined statically according to a standard or the like. Or, it may be determined quasi-statically or dynamically. The predetermined position may be determined by the eNB and notified to the LR-UE using RRC signaling. The predetermined position is, for example, the position of the SRS such as bits and symbols, the position from the start, the interval, the number of bits and symbols of the SRS, etc. The SRS may be multiplexed continuously or discontinuously.

[0818] The eNB may schedule the PUSCH for the LR-UE taking the SRS into consideration. The LR-UE maps the data obtained by multiplexing the PUSCH data and the SRS in the scheduled PUSCH region for the LR-UE and transmits it.

[0819] Figure 40This is a diagram for explaining the method of multiplexing and transmitting the SRS of the LR-UE with the PUSCH in Embodiment 10. In Figure 40 In the example shown, the SRS of the LR-UE is constituted by each symbol. The last symbol of the subframe, that is, the last symbol of the second time slot within the subframe, constitutes the SRS of the existing conventional UE. Therefore, in Figure 40 In the example shown, the last symbol of the second time slot within the subframe also constitutes the SRS of the LR-UE. The SRS of the conventional UE and the SRS of the LR-UE are multiplexed in this symbol. Thereby, the SRS of the conventional UE and the SRS of the LR-UE can coexist. The LR-UE can transmit the SRS by using the symbol constituting the SRS.

[0820] In the third and fifth symbols of the first time slot within the subframe, the SRS of the LR-UE and the PUSCH are multiplexed and mapped. Here, as the frequency region, 12 subcarriers are used. There may also be a frequency region in these symbols where the PUSCH is not mapped. In the first, third, and sixth symbols of the second time slot within the subframe, the SRS of the LR-UE and the PUSCH are multiplexed and mapped. Here, as the frequency region, two 12-subcarrier blocks are used.

[0821] Thereby, the mapping of the SRS and PUSCH of the LR-UE to the physical resources can be flexibly performed. In addition, the usage efficiency of the physical resources can be improved. In addition, the SRS can be dispersed over a wider frequency band, so that a frequency diversity gain can be obtained.

[0822] The PUCCH for the LR-UE is used to transmit the Ack / Nack for the SR, CSI, and downlink data. However, in the case of transmitting the PUCCH and SRS of the LR-UE using the same symbol, the same method as that of the PUCCH and SRS of the existing conventional UE can be adopted.

[0823] By using the method disclosed in this embodiment, the SRS of the LR-UE can be transmitted in symbol units. In addition, the SRS of the LR-UE and the SRS of the conventional UE can coexist on the same carrier of LTE.

[0824] Therefore, the eNB can receive the SRS of the LR-UE in symbol units and can use the SRS for efficient data scheduling to the LR-UE.

[0825] The decrease in the efficiency of the eNB in scheduling data to the conventional UE can be suppressed, and at the same time, the efficiency of scheduling data to the LR-UE can be improved.

[0826] Therefore, the decrease in the data transmission speed of the conventional UE can be suppressed, and the data transmission speed of the LR-UE can be improved.

[0827] In the above-described embodiment, a symbol unit SRS is disclosed to cope with the shortened TTI.

[0828] However, as another method, an existing subframe unit SRS transmission method or the slot unit SRS transmission method disclosed in Embodiment 5 can be used for the SRS transmission of the LR-UE.

[0829] In the scheduling of the eNB, there are cases where a symbol unit SRS is not required. For example, when the load of the cell is low. Even without a symbol unit SRS, the decrease in the scheduling efficiency of the eNB is small. In this case, by applying an existing subframe unit SRS transmission method or the slot unit SRS transmission method disclosed in Embodiment 5, an increase in the signaling amount can be suppressed. In addition, coexistence with traditional UEs becomes easy, so that complication of control can be avoided.

[0830] The symbol unit SRS, the slot unit SRS, and the subframe unit SRS can be appropriately combined. They can be used separately for each cell. They can be used separately for each UE. They can also be used separately in a quasi-static or dynamic manner. They can be used separately according to the load of the cell as a judgment criterion, the throughput of the cell, the average delay time of the cell, the communication quality of each UE, each requested QoS, each requested delay time, etc. Thereby, settings suitable for each service request can be made for a variety of services.

[0831] Embodiment 11.

[0832] The above-described embodiment discloses a method for supporting a UE (LR-UE) that operates with a shortened TTI. In addition, 3GPP has described the following situation: the shortening of the TTI for UEs in the connected state has been proposed. Therefore, after the UE transitions to the connected state, it will operate with a shortened TTI. The UE needs a method to switch to a shortened TTI after transitioning to the connected state. This embodiment discloses these methods. Here, the UE that switches to a shortened TTI is also referred to as an LR-UE.

[0833] The eNB notifies the LR-UE in the connected state of the TTI structure information. As the TTI structure information, there are a TTI value, the structure information of the physical channel, the structure information of the RS, etc.

[0834] As the TTI structure information, there are parameters configured for each cell or parameters configured for each UE. The parameters configured for each cell can be notified using cell-specific signaling or UE-specific signaling. The parameters configured for each UE can be notified using UE-specific signaling.

[0835] After the eNB notifies the TTI structure information to the LR-UE, it switches to this TTI structure for this LR-UE. Alternatively, after notifying the TTI structure information, the eNB can switch to this TTI structure for this LR-UE when it receives an affirmative response (Ack) to this notification from this LR-UE. Alternatively, after notifying the TTI structure information, the eNB can switch to this TTI structure for this LR-UE when it receives a completion message from the LR-UE using the setting of the TTI structure information.

[0836] After receiving the TTI structure information from the eNB, the LR-UE uses this TTI structure information to perform settings for related layers such as PHY and MAC, and starts transceiver operations.

[0837] Figures 41 to 43 It is a diagram showing an example of the related process for TTI switching for the LR-UE in Embodiment 11. Figures 41 to 43 It shows the case where the eNB separately notifies the TTI structure information to each UE. In addition, Figures 41 to 43 It shows the case of coexistence with a traditional UE. Figure 41 is connected to Figure 42 at the position of the boundary line BL1. Figure 42 is connected to Figure 43 at the position of the boundary line BL2.

[0838] In step ST4101, the traditional UE is in a state of communicating with the eNB using a TTI = 1 subframe. In step ST4102, the LR-UE is in a state of communicating with the eNB using a TTI = 1 subframe.

[0839] In step ST4103, the eNB determines to shorten the TTI for the LR-UE and sets it to TTI = 1 time slot.

[0840] In step ST4104, the eNB determines the LR-EPDCCH structure. In addition, the required TTI structure can also be determined. It can be determined by Figure 4 the control unit 411 for the LR-UE to determine the required TTI structure.

[0841] In step ST4105, the eNB notifies the LR-UE of the structure information of the shortened TTI. Here, the notification is performed using UE-specific RRC signaling. For example, the notification can be made from the eNB to the UE using the RRC Connection Reconfiguration message. The TTI structure information can also be included in the "RadioResourceConfigDedicated (Radio Resource Configuration Dedicated)" information within the RRC Connection Reconfiguration message. The TTI structure information can also be included in the "physicalConfigDedicated (Physical Configuration Dedicated)" information within the "RadioResourceConfigDedicated" information.

[0842] In step ST4108, the LR-UE uses the TTI structure information notified by the eNB to perform settings at related layers such as PHY and MAC. Here, TTI = 1 time slot. The setting using the TTI structure information in the LR-UE can be performed by Figure 3 the protocol processing unit 301. Alternatively, the control unit 310 processes the TTI structure information notified by the eNB, and the control unit 310 controls the protocol processing unit 301 to perform related layer settings.

[0843] The LR-UE that has completed the structure setting with TTI = 1 time slot notifies the eNB of the completion message of the setting in step ST4124. The notification of the completion message of the setting can use UE-specific RRC signaling. For example, the notification can be made from the UE to the eNB using the RRC Connection Reconfiguration Complete message.

[0844] In step ST4109, the LR-UE performs transmission and reception according to the set TTI structure information. Here, the structure when using LR-EPDCCH is shown. The LR-UE retrieves the LR-EPDCCH area using its own C-RNTI and detects its own PDCCH. In the LR-UE, Figure 3 the control unit 310 or the protocol processing unit 301 performs mapping to physical resources according to the set TTI structure information. The control unit 310 or the protocol processing unit 301 can control the transmission data buffer unit 303, the encoding unit 304, the modulation unit 305, the frequency conversion unit 306, the demodulation unit 308, and the decoding unit 309 according to the set TTI structure information.

[0845] In step ST4124, the eNB receives the completion message of the configuration from the LR-UE and schedules the legacy UE in TTI=1 subframe without any change in step ST4106. In addition, in step ST4107, the eNB starts scheduling the LR-UE in the configured TTI structure. The configuration using the TTI structure information in the eNB can be performed by Figure 4 The protocol processing unit 403 performs the TTI structure information configured for the LR-UE. The control unit 411 notifies the protocol processing unit 403 of the TTI structure information configured for the LR-UE and controls the protocol processing unit 403 to perform the configuration at the associated layer. The scheduler within the MAC layer enables scheduling based on the TTI structure configured for each UE, including legacy UEs and LR-UEs.

[0846] In addition, in the eNB, Figure 4 The control unit 411 or protocol processing unit 403 uses the configured TTI structure information to map each UE to physical resources. The control unit 411 or protocol processing unit 403 can control the transmit data buffer 404, encoding unit 405, modulation unit 406, frequency conversion unit 407, demodulation unit 409, and decoding unit 410 based on the configured TTI structure information.

[0847] In addition, in step ST4110, the traditional UE uses its own C-RNTI to retrieve the existing PDCCH area without change and detects its own PDCCH.

[0848] Figure 42 In steps ST4111 and ST4112, the eNB and the legacy UE perform transmission and reception using the same physical channels and RS as before, with a TTI=1 subframe structure. The legacy UE then performs data transmission and reception in step ST4116.

[0849] In steps ST4113 and ST4114, transmission and reception are performed between the eNB and the LR-UE using a shortened TTI (TTI = 1 slot). Physical channels and RSs in the TTI = 1 slot are used, and a mapping method for mapping these channels and RSs to physical resources is used. For example, the LR-EPDCCH, LR-PHICH, the LR-UE's PDSCH, the LR-UE's PUSCH, the LR-UE's PUCCH, and the LR-UE's SRS are used.

[0850] As a result, the LR-UE then sends and receives data in step ST4115.

[0851] In step ST4117, the LR-UE is in a state of communicating with the eNB in a time slot of TTI = 1. In step ST4118, the eNB decides to cancel the shortening of the TTI for the LR-UE.

[0852] Figure 43 In step ST4119, the eNB notifies the LR-UE of the release of the shortened TTI structure (TTI = 1 time slot). The notification of the release of the shortened TTI structure can use UE-specific RRC signaling. For example, the eNB can notify the UE using the RRC Connection Reconfiguration message. Information indicating the release can be set and included in this signaling for notification. Alternatively, the structure information of the TTI = 1 subframe can be included. The LR-UE can determine from this information that the release of the TTI = 1 time slot has been notified.

[0853] In step ST4119, the LR-UE notified of the release of the shortened TTI releases the setting of the shortened TTI (TTI = 1 time slot) in step ST4120. It can return to the setting of the existing TTI = 1 subframe.

[0854] The LR-UE that has completed the release of the TTI = 1 time slot setting notifies the eNB of the completion message of the setting release in step ST4125. The notification of the completion message of the setting release can use UE-specific RRC signaling. For example, the UE can notify the eNB using the RRC Connection Reconfiguration Complete message.

[0855] In step ST4127, the LR-UE performs transmission and reception with the setting of the existing TTI = 1 subframe. The LR-UE retrieves the PDCCH area using its own C-RNTI and detects its own PDCCH.

[0856] In step ST4125, the eNB that has received the completion message of the setting release from the LR-UE starts scheduling the LR-UE with the existing TTI structure (TTI = 1 subframe) in step ST4126.

[0857] In steps ST4121 and ST4122, transmission and reception are performed between the eNB and the LR-UE with the structure of the TTI = 1 subframe using the same physical channels and RS as before.

[0858] Thus, in step ST4123, the LR-UE releases the shortened TTI (TTI = 1 time slot) and communicates with the eNB with the existing TTI (TTI = 1 subframe).

[0859] Thus, the LR-UE in the connected state with the eNB can communicate with the shortened TTI.

[0860] In addition, the shortened TTI can also be released, and the TTI structure can be flexibly switched between the eNB and the LR-UE.

[0861] In addition, the eNB can communicate with the LR-UE using the shortened TTI and communicate with the legacy UE using the existing TTI. The communication between the LR-UE operating with the shortened TTI and the legacy UE operating with the existing TTI can coexist.

[0862] Figures 44 to 46 It is a diagram showing another example of the related process for TTI switching for the LR-UE in Embodiment 11. Figures 44 to 46 In the notification of the TTI structure information, for the information set for each cell in the TTI structure information, cell-specific signaling is used, and for the information set for each UE, UE-specific signaling is used. Figure 44 and Figure 45 are connected at the position of the boundary line BL3. Figure 45 and Figure 46 are connected at the position of the boundary line BL4.

[0863] Figures 44 to 46 The process shown in Figures 41 to 43 is similar to the process shown in, so the differences will be mainly described here.

[0864] In step ST4201, the legacy UE is in a state of communicating with the eNB using TTI = 1 subframe. In step ST4202, the LR-UE is in a state of communicating with the eNB using TTI = 1 subframe.

[0865] In step ST4203, the eNB determines the operation of the shortened TTI and determines the per-cell TTI structure information for this. As the per-cell TTI structure information, for example, the LR-EPDCCH structure per cell is set. In addition, here it is set to TTI = 1 time slot.

[0866] In steps ST4204 and ST4205, the eNB broadcasts the per-cell TTI structure information, such as the LR-EPDCCH structure information, to the LR-UE and the legacy UE.

[0867] In step ST4206, the eNB determines to shorten the TTI for the LR-UE and sets it to TTI = 1 time slot. In step ST4207, the eNB determines the per-UE TTI structure information.

[0868] In step ST4208, the eNB notifies the LR-UE of the per-UE TTI structure information. Here, the notification is performed using UE-specific RRC signaling.

[0869] Figure 45In step ST4211, the LR-UE uses the TTI structure information for each cell notified by the eNB and the TTI structure information for each UE notified individually by the eNB to perform configurations at the PHY and MAC layers. Here, TTI = 1 time slot.

[0870] The LR-UE that has completed the configuration of the TTI=1 time slot notifies the eNB of a configuration completion message in step ST4227. The notification of the configuration completion message can use UE-specific RRC signaling.

[0871] In step ST4212, the LR-UE performs transmission and reception according to the configured TTI structure information. Here, the case of using the LR-EPDCCH structure is shown. The LR-UE uses its own C-RNTI to search the LR-EPDCCH area and detect its own PDCCH.

[0872] In step ST4227, the eNB, having received the configuration completion message from the LR-UE, schedules the legacy UE in step ST4209 with TTI = 1 subframe without change. Furthermore, in step ST4210, the eNB starts scheduling the LR-UE with the configured TTI structure.

[0873] In addition, in step ST4213, the traditional UE uses its own C-RNTI to retrieve the existing PDCCH area without change and detects its own PDCCH.

[0874] In steps ST4214 and ST4215, the eNB and the legacy UE perform transmission and reception using the same physical channels and RS as before, with a TTI = 1 subframe structure.

[0875] In steps ST4216 and ST4217, transmission and reception are performed between the eNB and the LR-UE using a shortened TTI (TTI = 1 time slot). Transmission and reception are performed using physical channels and RSs in a TTI = 1 time slot structure, and using a mapping method that maps these channels and RSs to physical resources. For example, the LR-EPDCCH, LR-PHICH, LR-UE's PDSCH, LR-UE's PUSCH, LR-UE's PUCCH, LR-UE's SRS, etc. are used. As a result, the LR-UE then transmits and receives data in step ST4218.

[0876] Figure 46 In step ST4220, the LR-UE is in a state of communicating with the eNB in a time slot of TTI = 1. In step ST4221, the eNB decides to cancel the shortening of the TTI for the LR-UE.

[0877] In step ST4222, the eNB notifies the LR-UE of the release of the shortened TTI structure (TTI = 1 time slot). The notification of the release of the shortened TTI structure can use UE-specific RRC signaling. For example, it can be notified from the eNB to the UE using the RRC Connection Reconfiguration message. Information indicating the release can be set and included in this signaling for notification. Alternatively, the structure information of the TTI = 1 subframe can also be included. The LR-UE can determine from this information that the release of the TTI = 1 time slot has been notified.

[0878] In step ST4222, the LR-UE notified of the release of the shortened TTI releases the setting of the shortened TTI (TTI = 1 time slot) in step ST4223. It can return to the setting of the existing TTI = 1 subframe.

[0879] The LR-UE that has completed the release of the TTI = 1 time slot setting notifies the eNB of the completion message of the setting release in step ST4228. The notification of the completion message of the setting release can use UE-specific RRC signaling. For example, it can be notified from the UE to the eNB using the RRC Connection Reconfiguration Complete message.

[0880] In step ST4230, the LR-UE performs transmission and reception with the setting of the existing TTI = 1 subframe. The LR-UE retrieves the PDCCH area using its own C-RNTI and detects its own PDCCH.

[0881] In step ST4228, the eNB that has received the completion message of the setting release from the LR-UE starts scheduling the LR-UE with the existing TTI structure (TTI = 1 subframe) in step ST4229.

[0882] In steps ST4224 and ST4225, transmission and reception are performed between the eNB and the LR-UE with the structure of the TTI = 1 subframe using the same physical channels and RS as before.

[0883] Thus, in step ST4226, the LR-UE releases the shortened TTI (TTI = 1 time slot) and communicates with the eNB with the existing TTI (TTI = 1 subframe).

[0884] Accordingly, a part of the TTI structure information is set for each cell, and the TTI structure information of each cell is broadcast, so that the amount of TTI structure information to be notified for each UE can be reduced. For example, in the case where the TTI structure is frequently changed for an arbitrary UE, the amount of signaling for each UE required for the handover of the TTI structure can be reduced. Accordingly, the load of the signaling of the system can be reduced.

[0885] Embodiment 11 Variant 1.

[0886] In the above embodiment, the eNB determines the shortening of the TTI for the LR-UE. Alternatively, the release of the shortened TTI is determined. This variant discloses a method for the eNB to determine what kind of TTI to set for the LR-UE.

[0887] The eNB makes a determination using a predetermined determination index. As a specific example of the predetermined determination index, the following 11 types of (1) to (11) are disclosed.

[0888] (1) Service type.

[0889] (2) Data volume.

[0890] (3) QCI (QoS Class Identifier).

[0891] (4) RB type.

[0892] (5) Downlink communication quality.

[0893] (6) Uplink communication quality.

[0894] (7) HARQ number of times.

[0895] (8) Load status of the cell.

[0896] (9) Resource usage status of the cell.

[0897] (10) Transmission speed.

[0898] (11) A combination of (1) to (10) above.

[0899] A description is given of the specific example (1). The eNB makes a judgment based on the type of communication service or application that is the object. For example, it makes a judgment based on what kind of streaming data the service is. Or, for example, it makes a judgment based on whether it is real-time data stream. Or, for example, it makes a judgment based on whether it is buffered data stream. Or, for example, it makes a judgment based on whether it is FTP data. Or, for example, it makes a judgment based on whether it is a TCP-based service. Information on the type of communication service or application that is the object can be notified to the eNB by the core network or by the LR-UE. For example, in the case of streaming data, when it is a real-time data stream, the eNB determines the operation under shortened TTI, and when it is a buffered data stream, the eNB determines the operation under the existing TTI.

[0900] In addition, it can be judged based on whether the service is emergency communication. In the case of an emergency communication service, the eNB can determine the operation under the shortened TTI.

[0901] Thus, the delay amount can be improved according to the type of service or application, and the data transmission speed can be increased in terms of ability.

[0902] A description is given of the specific example (2). The eNB makes a judgment based on the data volume of the communication that is the object. For example, when the data volume is greater than a predetermined threshold, the eNB determines the operation under the shortened TTI, and when it is below the threshold, the eNB determines the operation under the existing TTI. Information on the data volume of the communication that is the object can be notified to the eNB by the core network or by the LR-UE. Or, it makes a judgment based on the data volume that has been received or transmitted. Or, it makes a judgment based on the remaining data volume. For example, when the remaining data volume is large, the operation under the shortened TTI can be determined. Or, it makes a judgment based on the change amount of the communication data volume. It can also make a judgment based on the change amount of the remaining data volume. As the data volume, the downlink buffer size or buffer status for the LR-UE can be used. In addition, the uplink buffer size or buffer status notified by the LR-UE can be used.

[0903] Thus, the delay amount can be improved according to the data volume of the communication, and the data transmission speed can be increased in terms of ability.

[0904] A description is given of the specific example (3). The eNB makes a judgment based on the QCI of the communication that is the object. For example, when the QCI is 1 or 4, the eNB determines the operation under the shortened TTI. Or, it can be judged based on the required delay amount. For example, when the required delay amount is below the threshold, the operation under the shortened TTI can be determined. When the required delay amount is greater than the threshold, the operation under the existing TTI is determined.

[0905] Thus, the delay amount can be improved according to the QCI of the communication or the required delay amount, and the ability map can improve the data transmission speed.

[0906] The specific example (4) will be described. The eNB makes a judgment based on the type of radio bearer (RB) of the communication being targeted. For example, in the case of a Data Radio Bearer (DRB), the eNB determines the operation under the shortened TTI. Alternatively, in the case of a pre-determined DRB, the eNB can determine the operation under the shortened TTI. Since the DRB is an RB for data, in many cases, an increase in the data transmission speed is required. Therefore, by operating with the shortened TTI, the ability map can improve the data transmission speed. In the case of a Signaling Radio Bearer (SRB), the eNB can determine the operation under the existing TTI. In comparison, the amount of communication data for an SRB is smaller at one time. This is because, in the case of transmitting and receiving a large amount of data, for the SRB, even if it is changed to the shortened TTI, the total time taken for transmission and reception remains basically unchanged.

[0907] Thus, the delay amount can be improved according to the RB of the communication, and the ability map can improve the data transmission speed.

[0908] The specific example (5) will be described. The eNB makes a judgment based on the downlink communication quality. For example, it receives the CQI or CSI from the UE for judgment. When the downlink communication quality between the eNB and the targeted UE is good, the eNB determines the operation under the shortened TTI. When the downlink communication quality is not good, the eNB determines the operation under the existing TTI. A threshold can be set for the index of the communication quality. The communication quality can be judged based on whether it is above or below the threshold.

[0909] In addition, it can be judged based on the change amount of the downlink communication quality. For example, when the change amount of the CQI or CSI is small, the eNB determines the operation under the shortened TTI. When the change amount of the downlink communication quality is large, the eNB determines the operation under the existing TTI. A threshold can be set for the index of the change amount of the communication quality. The change amount of the communication quality can be judged based on whether it is above or below the threshold. If the change amount is small, the communication quality is stable, and it can be inferred that the radio wave transmission environment is stable. The eNB determines the operation under the shortened TTI for this LR-UE with a stable radio wave transmission environment.

[0910] Thus, the delay amount can be improved according to the downlink communication quality, and the ability map can improve the data transmission speed.

[0911] The specific example (6) will be described. The eNB makes a judgment based on the uplink communication quality. For example, it receives PUCCH, PUSCH, uplink DMRS, or SRS from the UE to make a judgment. When the uplink communication quality between the eNB and the target UE is good, the eNB decides to operate under the shortened TTI. When the uplink communication quality is not good, the eNB decides to operate under the existing TTI. A threshold can be set for the index of the communication quality. The communication quality can be judged by whether it is above or below the threshold.

[0912] In addition, it can be judged by the change amount of the uplink communication quality. For example, when the change amount of the uplink DMRS is small, the eNB decides to operate under the shortened TTI. When the change amount of the downlink communication quality is large, the eNB decides to operate under the existing TTI. A threshold can be set for the index of the change amount of the communication quality. The change amount of the communication quality can be judged by whether it is above or below the threshold. If the change amount is small, it can be inferred that the communication quality is stable and the radio wave transmission environment is stable. The eNB decides to operate under the shortened TTI for this LR-UE with a stable radio wave transmission environment.

[0913] Thus, the delay amount can be improved according to the uplink communication quality, and the data transmission speed can be increased.

[0914] The specific example (7) will be described. The eNB makes a judgment based on the number of HARQ retransmissions. It can be for uplink HARQ or downlink HARQ. The number of past HARQ retransmissions can also be used for judgment. The number of HARQ retransmissions in a past predetermined period can be used for judgment. The average value of the predetermined period can be derived for judgment. For example, when the number of retransmissions is large, the eNB decides to operate under the shortened TTI. The number of HARQ retransmissions has a great impact on the delay. Therefore, in the situation where the number of HARQ retransmissions increases, the delay amount can be improved by using the shortened TTI.

[0915] Thus, the delay amount can be improved according to the number of HARQ retransmissions, and the data transmission speed can be increased.

[0916] Description is given to the specific example (8). The eNB makes a judgment based on the load condition of the cell. When the load of the cell is low, a shortened TTI is used; when the load of the cell is high, the existing TTI is used. When using the shortened TTI, it coexists with the existing TTI. Therefore, in addition to the physical resources for the existing TTI, physical resources for the shortened TTI are also required. Thus, when the load of the cell is high, the increase in this physical resource causes the capacity of the system to decrease. Therefore, the shortened TTI is configured according to the load of the cell. Thereby, the delay amount of the system can be improved and the data transmission speed can be increased as much as possible.

[0917] Description is given to the specific example (9). The eNB makes a judgment based on the usage condition of the cell resources. When the usage condition of the cell resources is low, a shortened TTI is used; when the usage condition of the cell resources is high, the existing TTI is used. Similar to the specific example (8), when the usage condition of the cell resources is high, the increase in this physical resource causes the capacity of the system to decrease. Therefore, the shortened TTI is configured according to the usage condition of the cell resources. Thereby, the delay amount of the system can be improved and the data transmission speed can be increased as much as possible.

[0918] Description is given to the specific example (10). The eNB makes a judgment based on the data transmission speed. When the data transmission speed between the eNB and the UE is low, a shortened TTI is used; when the data transmission speed between the eNB and the UE is high, the existing TTI is used. When the data transmission speed is low, in order to increase the data transmission speed as much as possible, the shortened TTI is used. When the data transmission speed is high, it is assumed that the desired data transmission speed has been obtained and the existing TTI is used. Thereby, the shortened TTI can be configured according to the data transmission speed. Therefore, the delay amount of the system can be improved and the data transmission speed can be increased as much as possible.

[0919] By using the above judgment metrics, the eNB can determine the shortened TTI for the LR-UE according to the communication condition. In the description of the judgment metrics, the judgment on whether to shorten the TTI is described, but it can also be appropriately applied to the case of configuring multiple shortened TTIs. Thereby, multiple shortened TTIs, such as 1 time slot, 1 symbol, and the existing TTI (1 subframe), can be used separately.

[0920] As described above, in this Modification 1, a method for the eNB to determine what TTI to set for the LR-UE is disclosed. This determination can also be requested by the LR-UE to the eNB. The LR-UE can also request the eNB to change the TTI setting.

[0921] The LR-UE notifies the eNB of a TTI setting change request. The notification of the TTI setting change request can be made using UE-specific RRC signaling.

[0922] The eNB that has received the TTI setting change request determines for the LR-UE that sent the request whether to shorten the TTI and what TTI length to set.

[0923] For example, Figures 41 to 43 in, before the processing of step ST4103, the LR-UE notifies the eNB of the TTI setting change request.

[0924] The LR-UE can also make a determination on whether to make this notification before notifying the TTI setting change request. The determination criteria for whether to notify the TTI setting change request can be of a type that can be appropriately applied on the LR-UE side using the above determination criteria.

[0925] The LR-UE can notify the eNB of the determination criteria and their values. The eNB can recognize the determination criteria and their values in the LR-UE. The LR-UE can notify the eNB of the TTI setting change request and the determination criteria and their values. The eNB can recognize the request and the determination criteria and their values in the LR-UE, and using this information, can determine for this LR-UE whether to change the TTI setting as requested.

[0926] The eNB can notify the UE of information on whether the TTI structure can be changed. The notification can be made for each cell. At least one of the information on whether the TTI structure can be changed and the information on the supported TTI structure is set, and the eNB notifies the UE in each cell. The information on the supported TTI structure can be the TTI type shown in Modification Example 2 of Embodiment 11.

[0927] As a notification method, it can be included in the broadcast information for broadcasting. Or, it can be notified to each UE individually using dedicated RRC signaling. Thus, the UE under the eNB coverage can recognize the TTI structure supported by the cell and whether the TTI structure can be changed. Therefore, the LR-UE can notify the TTI setting change request to the cell that supports the desired TTI structure and the change of the TTI structure.

[0928] The eNB that has received the TTI setting change request from the LR-UE can determine not to change the TTI setting. In this case, the LR-UE that sent the TTI setting change request can be notified of the rejection of the TTI setting change. The eNB can notify the reason (cause) for the rejection while notifying the rejection. The LR-UE that has received this rejection message can be considered not to change the TTI setting and continue to communicate with the current TTI setting.

[0929] The eNB can notify the prohibition period of the TTI setting change request while notifying the rejection. The LR-UE that receives the prohibition period of the TTI setting change request cannot notify the eNB of the TTI setting change request during this period. The eNB can prevent the continuous transmission of this request from the LR-UE, reducing the signaling volume in the capacity diagram. In addition, the eNB can set this period according to the conditions of the cell, such as the load condition, etc. Thus, the LR-UE can be controlled to notify this request during an appropriate period.

[0930] By using the method disclosed in this modification example, the TTI structure can be adaptively changed according to the conditions of the LR-UE and the surrounding radio wave transmission environment, etc.

[0931] In addition, since the LR-UE can request a change in the TTI setting, for communication quality, etc., the result obtained by the LR-UE's own measurement can be used to make an immediate request. The eNB can avoid using rough-precision communication quality information such as CQI / CSI obtained from the LR-UE. Therefore, a TTI structure with higher precision can be adaptively set. Thus, the transmission speed can be further improved.

[0932] Embodiment 11 Modification Example 2.

[0933] In the above embodiment, the eNB determined the shortening of the TTI for the LR-UE. The eNB needs to identify in advance whether the target UE can support the shortened TTI.

[0934] In this modification example, a method for the eNB to identify whether the UE can support the shortened TTI is disclosed.

[0935] An indication of whether multiple TTIs can be supported is set. Information on the type of the corresponding TTI can also be set. For example, TTI = 1 subframe, TTI = 1 time slot, TTI = 1 symbol, etc. The type of each TTI can be represented by one bit or multiple bits. This bit can also be determined in advance. For example, represented by 2 bits, TTI = 1 subframe is set to 10, TTI = 1 time slot is set to 01, and TTI = 1 symbol is set to 00. The type of TTI can be represented with less information volume. TTI = 1 subframe can be the default without setting. In addition, information on the number of TTI types that can be supported simultaneously can also be set. In addition, information for determining the notified UE, such as the UE identifier, can be included.

[0936] The above information is hereinafter referred to as "multiple TTI information". The multiple TTI information can be included in the UE capability information.

[0937] For an eNB, a UE can notify the eNB of multiple TTI information. Alternatively, it can be notified to a network - side node. The network - side node can notify the eNB of the multiple TTI information received from the UE as needed. The UE can use the notification method of UE capability information to notify the eNB of multiple TTI information.

[0938] Thus, the eNB can receive the TTI information of the UE, and the UE can identify whether it supports multiple TTIs. Therefore, the eNB can use the multiple TTI information received from the UE to change the TTI structure for this UE and can notify the UE of the TTI structure.

[0939] The LR - UE can change the TTI structure by receiving a notification of TTI structure change from the eNB and can communicate with the eNB according to this TTI structure. Thus, when the set TTI structure is a shortened TTI, communication can be performed with the shortened TTI.

[0940] Embodiment 12.

[0941] In Embodiment 11, a method for switching to a shortened TTI for an LR - UE after transitioning to the connected state is disclosed. A method for enabling an eNB and a UE to support multiple TTI structures simultaneously as a system is disclosed.

[0942] As a system, multiple TTIs can be set simultaneously. The eNB can set multiple TTIs for any LR - UE in the connected state. The eNB can set multiple TTIs for an LR - UE that can support multiple TTIs simultaneously.

[0943] The physical resources of the physical channels constituting each TTI can be mapped in a non - conflicting manner. In the above - mentioned embodiment, it is disclosed that the physical resources of the physical channels mapped for the shortened TTI structure and the physical resources of the physical channels mapped for the existing TTI structure do not conflict. Here, by further applying the method disclosed in the above - mentioned embodiment, it is sufficient that the physical resources of the physical channels mapped for multiple shortened TTI structures do not conflict. The physical channels and the physical resources mapped with the physical channels can be configured in a non - conflicting manner.

[0944] As a method for the eNB to determine whether the target UE can support multiple TTIs simultaneously, the method disclosed in Variant Example 2 of Embodiment 11 can be applied. Information on whether the UE can support multiple TTIs simultaneously can be set and included in the multiple TTI information. When the UE notifies the eNB of the multiple TTI information, information on whether it can support multiple TTIs simultaneously can also be notified. Thus, the eNB can determine whether the target UE can support multiple TTIs simultaneously.

[0945] Disclosed is an example of supporting multiple TTIs for one LR-UE. For example, the eNB transmits to the LR-UE in multiple TTIs according to the type of downlink control information. The control information mapped to the CSS (Common Search Space) (refer to Non-Patent Document 12) uses the existing TTI, and the control information mapped to the USS (UE specific Search Space) (refer to Non-Patent Document 12) uses the shortened TTI.

[0946] As the control information mapped to the CSS, there is SIB control information, paging control information, and RAR (Random Access Response) control information. These control information are not the control information for UE-specific data. These control information do not detect the PDCCH using the C-RNTI of the LR-UE itself, but use the RNTI determined in advance for each cell or as a system to detect the PDCCH. Therefore, by using the existing TTI in the transmission of the control information mapped to this CSS, the same method as the existing reception method of this control information for traditional UEs can be adopted. Thus, there is no need to separately ensure new physical resources in each LR-UE, and in addition, there is no need to generate paging for traditional UEs and paging for LR-UEs with different mechanisms. Similarly, there is no need to generate RAR for traditional UEs and RAR for LR-UEs with different mechanisms. Therefore, the utilization efficiency of physical resources can be improved, and the complication of control can be avoided. In addition, the control can be made simple and the installation can be made easy.

[0947] As the control information mapped to the USS, there is control information for data used for UE-specific communication. This control information detects the PDCCH region using the C-RNTI of the LR-UE itself. Therefore, by using the shortened TTI in the transmission of the control information mapped to this USS, the delay of data used for UE-specific communication can be reduced. Thus, the data transmission speed of the LR-UE can be improved.

[0948] Figures 47 to 49 It is a diagram showing an example of the relevant process of the process of supporting multiple TTIs for one LR-UE in Embodiment 12. Figures 47 to 49 Among them, the control information mapped to the CSS uses the existing TTI (TTI = 1 subframe), and the control information mapped to the USS uses the shortened TTI. As the shortened TTI, in the Figures 47 to 49 example shown, it is set to TTI = 1 time slot. In addition, Figures 47 to 49 shows the situation of coexisting with traditional UEs. Figure 47 Connected to Figure 48 at the position of the boundary line BL5. Figure 48 Connected toFigure 49 Connected at the position of the boundary line BL6.

[0949] In step ST4301, the traditional UE is in a state of communicating with the eNB with a TTI = 1 subframe. In step ST4302, the LR-UE is in a state of communicating with the eNB with a TTI = 1 subframe.

[0950] In step ST4303, the eNB decides to apply a shortened TTI for the LR-UE. As the shortened TTI, it is set to TTI = 1 time slot. For the LR-UE, the eNB decides to use the existing TTI for the control information mapped to the CSS and the shortened TTI for the control information mapped to the USS.

[0951] In step ST4304, the eNB determines the LR-EPDCCH structure for the shortened TTI. In addition, the required TTI structure can also be determined.

[0952] In step ST4305, the eNB notifies the LR-UE of the structure information of the shortened TTI. Here, the notification is performed using UE-specific RRC signaling. For example, it can be notified from the eNB to the UE using the RRC Connection Reconfiguration message. The TTI structure information can also be included in the "RadioResourceConfigDedicated (Radio Resource Configuration Dedicated)" information in the RRC connection reconfiguration message. The TTI structure information can also be included in the "physicalConfigDedicated (Physical Configuration Dedicated)" information in the "RadioResourceConfigDedicated" information.

[0953] In addition, information can be set to indicate that the existing TTI is used for the control information mapped to the CSS and the shortened TTI is used for the control information mapped to the USS. The eNB notifies the LR-UE of the TTI structure information and this information. This information can also be included in the TTI structure information for notification.

[0954] In step ST4308, the LR-UE uses the TTI structure information notified by the eNB to perform the settings at the associated layers such as PHY and MAC. Here, TTI = 1 time slot. The LR-UE also maintains the settings at the associated layer based on the existing TTI (TTI = 1 subframe) structure. That is, the settings at the associated layer for the two TTI structures of the existing TTI and the shortened TTI are performed. The LR-UE can operate with two TTIs.

[0955] The LR-UE that has completed the configuration of the TTI=1 time slot notifies the eNB of the completion of the configuration in step ST4326. The notification of the completion of the configuration can use UE-specific RRC signaling. For example, it can be notified from the UE to the eNB using the RRC Connection Reconfiguration Complete message.

[0956] In step ST4330, the LR-UE maintains the transmission and reception based on the existing TTI structure. The LR-UE retrieves the existing PDCCH area using its own C-RNTI and detects its own PDCCH. Thereby, it can receive the control information mapped to the CSS. In addition, it can perform transmission and reception according to this control information.

[0957] In step ST4309, the LR-UE performs transmission and reception according to the shortened TTI structure information. Here, the structure when using LR-EPDCCH is shown. The LR-UE searches the LR-EPDCCH area using its own C-RNTI and detects its own PDCCH. Thereby, it can receive the control information mapped to the USS. In addition, it can perform transmission and reception according to this control information.

[0958] In step ST4326, the eNB that has received the completion message of the configuration from the LR-UE, in step ST4307, for the LR-UE, starts scheduling the control information mapped to the CSS using the existing TTI, and starts scheduling the control information mapped to the USS using the shortened TTI. Thereby, for the control information mapped to the CSS, the method using the existing TTI is used, and for the control information mapped to the USS, the method using the shortened TTI is used. These can be performed simultaneously between the eNB and the LR-UE.

[0959] In step ST4306, the eNB schedules the legacy UE without change using the existing TTI.

[0960] In addition, in step ST4310, the legacy UE retrieves the existing PDCCH area using its own C-RNTI without change and detects its own PDCCH.

[0961] Figure 48 In steps ST4311 and ST4312, between the eNB and the legacy UE, in the structure of TTI=1 subframe, transmission and reception are performed using the same physical channels and RS as before. Thereby, then the legacy UE performs data transmission and reception in step ST4116.

[0962] In step ST4313, between the eNB and the LR-UE, for the control information mapped to the CSS, transmission and reception are performed using the existing TTI structure, i.e., the structure of a TTI = 1 subframe. Transmission and reception are performed using the physical channels and RSs of the existing TTI = 1 subframe structure, and using the mapping method that maps the channels and RSs to physical resources. For example, PDCCH, PDSCH, etc. are used.

[0963] In steps ST4314 and ST4315, between the eNB and the LR-UE, transmission and reception are performed using the shortened TTI structure, i.e., the structure of a TTI = 1 time slot. Transmission and reception are performed using the physical channels and RSs of the TTI = 1 time slot structure, and using the mapping method that maps the channels and RSs to physical resources. For example, LR-EPDCCH, LR-PHICH, the PDSCH of the LR-UE, the PUSCH of the LR-UE, the PUCCH of the LR-UE, the SRS of the LR-UE, etc. are used.

[0964] Thus, in step ST4316, the LR-UE simultaneously uses two TTIs to perform data transmission and reception.

[0965] In step ST4318, between the eNB and the LR-UE, transmission and reception of the control information mapped to the CSS are performed using the existing TTI.

[0966] In step ST4319, between the eNB and the LR-UE, transmission and reception of the control information mapped to the USS are performed using the shortened TTI.

[0967] Figure 49 In step ST4320, the eNB notifies the LR-UE of the release of the TTI shortening.

[0968] In step ST4321, the eNB notifies the LR-UE of the release of the shortened TTI structure (TTI = 1 time slot). For the control information mapped to the USS, it is possible to notify the release of using the shortened TTI.

[0969] The notification of the release of the shortened TTI structure can use UE-specific RRC signaling. For example, it is possible to notify from the eNB to the UE using the RRC Connection Reconfiguration message. Information indicating the release can be set and included in this signaling for notification. Or, the structure information of the TTI = 1 subframe can be included. The LR-UE can determine from this information that the release of the TTI = 1 time slot has been notified.

[0970] In step ST4321, the LR-UE that is notified to release the shortened TTI releases the setting of the shortened TTI (TTI = 1 time slot) in step ST4322. Regarding the control information mapped to the USS, the setting of the existing TTI = 1 subframe can be restored. Thus, regarding the control information mapped to the CSS and the control information mapped to the USS, both become the setting of the existing TTI = 1 subframe.

[0971] The LR-UE that has completed the release of the TTI = 1 time slot setting notifies the eNB of the completion message of the setting release in step ST4327. The notification of the completion message of the setting release can use UE-specific RRC signaling. For example, it can be notified from the UE to the eNB using the RRC Connection Reconfiguration Complete message.

[0972] In step ST4329, the LR-UE performs transmission and reception with the setting of the existing TTI = 1 subframe. The LR-UE retrieves the PDCCH area using its own C-RNTI and detects its own PDCCH.

[0973] In step ST4327, the eNB that receives the completion message of the setting release from the LR-UE starts scheduling both the control information mapped to the CSS and the control information mapped to the USS for the LR-UE with the existing TTI structure (TTI = 1 subframe) in step ST4328.

[0974] In steps ST4323 and ST4324, transmission and reception are performed between the eNB and the LR-UE with the structure of the TTI = 1 subframe using the same physical channels and RS as before.

[0975] Thus, in step ST4325, the LR-UE releases multiple TTIs using the shortened TTI and communicates with the eNB using the existing one TTI.

[0976] Thus, multiple TTIs can be supported for one LR-UE. By using them separately as described above, the utilization efficiency of physical resources can be improved, the complexity of control can be avoided, and the data transmission speed of this LR-UE can be increased.

[0977] Other examples of supporting multiple TTIs for one LR-UE are disclosed. For example, the eNB sets different TTIs for each RB for the LR-UE. By setting different TTIs for each RB for one LR-UE, the eNB can communicate with the LR-UE using multiple TTIs simultaneously.

[0978] For example, the eNB uses a shortened TTI only for a predetermined DRB. For other RBs, the existing TTI is used. In addition...

Claims

1. A communication system that utilizes sub - frames; a plurality of time slots included in the sub - frames; and communicating using a plurality of symbols included in each of the plurality of time slots, characterized in that comprises: a base station that transmits a physical downlink shared channel scheduled in time domain in units of time slots; and a communication terminal that receives from the base station information related to the symbol number at the start of allocation of the physical downlink shared channel in the time slot, and receives the physical downlink shared channel based on the information.

2. The communication system according to claim 1, wherein the number of processes of hybrid automatic repeat request corresponding to the transmission time interval is applied.

3. The communication system according to claim 1 or 2, wherein the physical downlink shared channel is configured in a plurality of non - consecutive frequency regions within the time slot.

4. A base station, which is a base station in a communication system that utilizes sub - frames; a plurality of time slots included in the sub - frames; and a plurality of symbols included in each of the plurality of time slots for communication, characterized in that the base station transmits a physical downlink shared channel scheduled in time domain in units of time slots to a communication terminal, and transmits to the communication terminal information related to the symbol number at the start of allocation of the physical downlink shared channel in the time slot.

5. The base station according to claim 4, wherein the number of processes of hybrid automatic repeat request corresponding to the transmission time interval is applied.

6. The base station according to claim 4 or 5, wherein the physical downlink shared channel is configured in a plurality of non - consecutive frequency regions within the time slot.

7. A communication terminal, which is a communication terminal in a communication system that utilizes sub - frames; a plurality of time slots included in the sub - frames; and a plurality of symbols included in each of the plurality of time slots for communication, characterized in that the communication terminal receives a physical downlink shared channel scheduled in time domain in units of time slots from a base station, receives from the base station information related to the symbol number at the start of allocation of the physical downlink shared channel in the time slot, and receives the physical downlink shared channel based on the information.

8. The communication terminal according to claim 7, wherein the number of processes of hybrid automatic repeat request corresponding to the transmission time interval is applied.

9. The communication terminal according to claim 7 or 8, wherein the physical downlink shared channel is configured in a plurality of non - consecutive frequency regions within the time slot.

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