Wireless communication system, base station and communication terminal

Abstract

The present invention relates to a wireless communication system, a base station, and a communication terminal. The base station device of the present invention is configured to set the wireless format of the signal transmitted and received between the base station device and the communication terminal device for each communication terminal device. The wireless format is set for each communication terminal device according to the usage mode including, for example, the moving speed of the communication terminal device. The base station device can be configured to change the wireless format for the communication terminal device according to the environmental changes of the wireless communication between the base station device and the communication terminal device and the change information including the position of the communication terminal device. The signal transmitted and received between the base station device and the communication terminal device includes a plurality of wireless formats that are different in at least one of the symbol length of the signal in the OFDM method and the length of the cyclic prefix.

Description

[0001] This invention application is a divisional application of the invention patent application with international application number PCT / JP2015 / 080097, international application date October 26, 2015, application number 201580059270.2 entering the Chinese national phase, and name “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 3rd Generation Partnership Project (3GPP), a standardization body for mobile communication systems, a communication method called Long Term Evolution (LTE) in terms of wireless sections and System Architecture Evolution (SAE) in terms of the overall system structure including a core network and a radio access network (hereinafter collectively referred to as a network) is studied (for example, see non-patent documents 1 to 12). This communication method is also called a 3.9G (3.9 generation) system.

[0004] As the 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, unlike W-CDMA (Wideband Code division Multiple Access), LTE does not include line switching and is only a packet communication method.

[0005] use Figure 1 The decision matters concerning the frame structure of the LTE system in 3GPP described in Non-Patent Document 1 (Chapter 5) are described. Figure 1 This is an explanatory diagram showing the structure of a radio frame used in a communication system of the LTE method. Figure 1In the IEEE 802.11 standard, a radio frame is 10ms. A radio frame is divided into 10 subframes of equal size. A subframe is divided into two slots of equal size. The first and sixth subframes of each radio frame contain a downlink synchronization signal. The synchronization signal has a primary synchronization signal (P-SS) and a secondary synchronization signal (S-SS).

[0006] Non-Patent Document 1 (Chapter 5) describes the decisions made by 3GPP regarding the channel structure of the LTE system. It is assumed that the same channel structure as that of the non-CSG cell is used in the CSG (Closed Subscriber Group) cell.

[0007] The physical broadcast channel (PBCH) is a downlink transmission channel from a base station device (hereinafter sometimes referred to as "base station") to a communication terminal device (hereinafter sometimes referred to as "communication terminal") such as a mobile terminal device (hereinafter sometimes referred to as "mobile terminal"). The BCH transport block is mapped to four subframes in a 40ms interval. There is no clear signaling of 40ms 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 the communication terminal of the number of OFDM (Orthogonal Frequency Division Multiplexing) symbols used for PDCCHs from the base station. The PCFICH is transmitted in each subframe.

[0009] The Physical Downlink Control Channel (PDCCH) is a channel for downlink transmission from the base station to the communication terminal. PDCCH notifies the resource allocation information of the downlink shared channel (DL-SCH), one of the transmission channels described later, the resource allocation information of the paging channel (PCH), one of the transmission channels described later, and the HARQ (Hybrid Automatic Repeat reQuest) information related to the DL-SCH. PDCCH transmits the uplink scheduling grant. PDCCH transmits the response signal to the uplink transmission, namely Ack (Acknowledgement) / Nack (Negative Acknowledgement). PDCCH is also called L1 / L2 control signal.

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

[0011] A physical multicast channel (PMCH) is a channel for downlink transmission from a base station to a communication terminal. A multicast channel (MCH) as a transport channel is mapped to the PMCH.

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

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

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

[0015] The downlink reference signal (Reference Signal: RS) is a known codeword in the LTE communication system. The following five types of downlink reference signals are defined. Cell-specific Reference Signals (CRS), MBSFN reference signals (MBSFN reference signals), UE-specific reference signals (UE-specific reference signals), i.e., Data Demodulation Reference Signal (DM-RS), Positioning Reference Signals (PRS), Channel-State Information Reference Signals (CSI-RS). As a measurement of the physical layer of the communication terminal, there is a measurement of the reference signal received power (Reference Signal Received Power: RSRP).

[0016] The transport channel described in Non-Patent Document 1 (Chapter 5) is described below. Among downlink transport channels, the broadcast channel (BCH) is broadcast to the entire coverage area of ​​its base station (cell). The BCH is mapped to the physical broadcast channel (PBCH).

[0017] Retransmission control using HARQ (HybridARQ) is applied to the downlink shared channel (DL-SCH). DL-SCH can broadcast to the entire coverage area of ​​the base station (cell). DL-SCH supports dynamic or semi-static resource allocation. Quasi-static resource allocation is also called persistent scheduling. In order to reduce the power consumption of the communication terminal, DL-SCH supports discontinuous reception (DRX) of the communication terminal. 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 reduce the power consumption of the communication terminal. The PCH is required to be broadcast to the entire coverage area of ​​the base station (cell). The PCH is mapped to a physical resource such as the Physical Downlink Shared Channel (PDSCH) that can be dynamically used for traffic.

[0019] The Multicast Channel (MCH) is used to broadcast to the entire coverage area of ​​the base station (cell). The MCH supports SFN synthesis of MBMS (Multimedia Broadcast Multicast Service) services (MTCH and MCCH) in multi-cell transmission. The MCH supports quasi-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. UL-SCH supports dynamic or semi-static resource allocation. 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 is an explanation of HARQ. HARQ is a technology that improves the communication quality of a transmission line by combining Automatic RepeatreQuest (ARQ) and Forward Error Correction (Forward Error Correction). The advantage of HARQ is that even for a transmission line with changed communication quality, error correction can be effectively used by retransmission. In particular, when retransmission is performed, the quality can be further improved by synthesizing the reception result of the first transmission and the reception result of the retransmission.

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

[0024] The logical channel described in Non-Patent Document 1 (Chapter 6) is described below. 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) as a transport channel or the Downlink Shared Channel (DL-SCH).

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

[0026] The Common Control Channel (CCCH) is a channel used to send control information between a communication terminal and a base station. The CCCH is used when there is no 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 more MTCHs from the network to the communication terminal. The MCCH is only used for communication terminals that are receiving MBMS. The MCCH is mapped to the Multicast Channel (MCH) as a transport channel.

[0028] Dedicated Control Channel (DCCH) is a channel used to send dedicated control information between a communication terminal and the network in a point-to-point manner. DCCH is used when the communication terminal is in an RRC connection. DCCH is mapped to the uplink shared channel (UL-SCH) in the uplink and to the downlink shared channel (DL-SCH) in the downlink.

[0029] Dedicated Traffic Channel (DTCH) is a channel used to send user information and perform point-to-point communication with a single communication terminal. DTCH exists in both uplink and downlink. DTCH is mapped to the uplink shared channel (UL-SCH) in the uplink and to the downlink shared channel (DL-SCH) in the downlink.

[0030] A multicast traffic channel (MTCH) is a downlink channel for transmitting traffic data from a network to a communication terminal. The MTCH is a channel used only for a communication terminal that is receiving MBMS. The MTCH is mapped to a multicast channel (MCH).

[0031] CGI stands for Cell Global Identification. ECGI stands for E-UTRAN Cell Global Identifier. CSG (Closed Subscriber Group) cells are introduced in LTE, LTE-A (Long Term Evolution Advanced) described later, and UMTS (Universal Mobile Telecommunication System).

[0032] CSG (Closed Subscriber Group) cells are cells that are designated by operators as subscribers with the right to use (hereinafter sometimes referred to as "cells for specific subscribers"). Specific subscribers are allowed to access one or more cells of the PLMN (Public Land Mobile Network). One or more cells that specific subscribers are allowed to access are called "CSG cells (CSG cell(s))". However, there are access restrictions to PLMN.

[0033] The CSG cell is a part of the PLMN that broadcasts a unique CSG identity (CSG ID) and broadcasts TRUE using a CSG indication (CSG Indication). Members of the subscriber group who have registered for use in advance and are permitted access the CSG cell using the CSG_ID in the access permission information.

[0034] CSG_ID is broadcast by a CSG cell or cells. A plurality of CSG_IDs exist in the LTE communication system. In addition, in order to facilitate access of members associated with the CSG, the CSG_ID is used by a communication terminal (UE).

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

[0036] In 3GPP, base stations called Home-NodeB (Home-NB; HNB) and Home-eNodeB (Home-eNB; HeNB) are studied. HNB in ​​UTRAN and HeNB in ​​E-UTRAN are base stations for access services for homes, corporations, and businesses, for example. Non-patent document 3 discloses three different modes of access to HeNB and HNB. 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, HeNB and HNB are operated as regular cells for normal operators. In the closed access mode, 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, HeNB and HNB are operated as CSG cells that non-CSG members are also allowed to access. In other words, a 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 PCI range reserved by the network for use by CSG cells among all physical cell identities (PCI) (see Chapter 10.5.1.1 of Non-Patent Document 1). The situation of dividing the PCI range is sometimes called PCI splitting. Information related to PCI splitting (also called PCI splitting information) is broadcast from the base station to the communication terminals under its coverage through system information. Being covered by a base station means using the base station as a service cell.

[0039] Non-patent document 4 discloses the basic operation of a communication terminal using PCI splitting. A communication terminal without PCI splitting information needs to use all PCIs, for example, all 504 codes, to search for cells. In contrast, a communication terminal with PCI splitting information can use the PCI splitting information to search for cells.

[0040] In addition, 3GPP is advancing the standardization of Long Term Evolution Advanced (LTE-A) as Release 10 (see Non-Patent Documents 5 and 6). LTE-A is based on the wireless communication method of LTE and is constructed by adding some new technologies thereto.

[0041] In the LTE-A system, in order to support wider bandwidths (transmission bandwidths) up to 100 MHz, carrier aggregation (CA) of aggregating (also called “aggregation”) two or more component carriers (CCs) is being studied.

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

[0043] A secondary serving cell (SCell) is formed according to the capability (capability) of the UE to form a group of PCell and serving cell. 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 PCell and a group of service cells consisting of one or more SCells are formed.

[0045] In addition, new technologies of LTE-A include technologies that support wider bandwidths (Wider bandwidth extension) and coordinated multiple point transmission and reception (CoMP) technologies. CoMP, which is being studied to implement LTE-A in 3GPP, is described in Non-Patent Document 7.

[0046] Mobile network traffic is increasing, and communication speeds are also increasing. If LTE and LTE-A are put into full-scale use, communication speeds will be further increased, and traffic will continue to increase.

[0047] The popularity of smartphones and tablet computers has led to an explosive increase in the volume of cellular wireless communications, leading to concerns about the shortage of wireless resources in the world.

[0048] In response to the problem of increasing traffic, 3GPP is continuously advancing the formulation of the Release 12 technical standard. In the Release 12 technical standard, in order to cope with the huge traffic in the future, the use of small cell eNBs is studied. For example, the technology of increasing the communication capacity by setting up multiple small cell eNBs and forming multiple small cell cells is studied.

[0049] Among them, dual connectivity is discussed as a technology for connecting a communication terminal to both a macro cell and a small cell when a macro cell and a small cell overlap (see non-patent document 11). Non-patent document 11 discloses dual connectivity as a technology for connecting a communication terminal to both a macro cell and a small cell when a macro cell and a small cell overlap.

[0050] In addition, in response to increasingly sophisticated mobile communications, fifth-generation (hereinafter sometimes referred to as "5G") wireless access systems are being studied with the goal of starting services after 2020. For example, in Europe, a group called METIS has compiled requirements for 5G (see Non-Patent Document 12).

[0051] The following requirements are listed for the 5G wireless access system: system capacity is 1000 times that of the LTE system, data transmission speed is 100 times that of the LTE system, data processing delay is one tenth (1 / 10) of the LTE system, the number of simultaneous connections of communication terminals is 100 times that of the LTE system, and lower power consumption and low cost of equipment are achieved.

[0052] In order to meet the above requirements, research is being conducted on increasing the data transmission capacity by using frequencies in a wide bandwidth, and on antenna shaping technology that can achieve spatial multiplexing by increasing the frequency utilization efficiency to increase the data transmission capacity. In addition, in order to ensure the frequency of a wide bandwidth, research is being conducted on using high frequencies such as the microwave (Super High Frequency: SHF) band of 3 to 30 GHz as the frequency used for wireless access.

[0053] When high frequencies are used, the wavelength becomes shorter, so the attenuation of radio waves increases, and the transmission distance of radio waves becomes shorter than that of previous communication systems. In addition, the influence of Doppler shift becomes larger, and the moving speed of the communication terminal sometimes has a significant impact on communication performance.

[0054] In addition, various communication terminals are accommodated in the 5G wireless access system, so as a wireless access method, from communication terminals that support high-speed data transmission such as 4K digital TVs to communication terminals that only support ultra-low-speed data transmission such as sensors, they all need to be processed by the same system.

[0055] Therefore, the existing LTE communication method is difficult to meet the requirements of 5G, so it is necessary to study new methods as 5G wireless access methods.

[0056] Prior art literature

[0057] Non-patent literature

[0058] Non-patent document 1: 3GPP TS36.300 V11.7.0

[0059] Non-patent document 2: 3GPP TS36.304 V11.2.0

[0060] Non-patent document 3: 3GPP S1-083461

[0061] Non-patent document 4: 3GPP R2-082899

[0062] Non-patent document 5: 3GPP TR36.814 V9.0.0

[0063] Non-patent document 6: 3GPP TR36.912 V10.0.0

[0064] Non-patent document 7: 3GPP TR36.819 V11.1.0

[0065] Non-patent document 8: 3GPP TS36.141 V11.1.0

[0066] Non-patent document 9: 3GPP R1-134496

[0067] Non-patent document 10: 3GPP R1-132236

[0068] Non-patent document 11: 3GPP TR36.842 V0.2.0

[0069] Non-Patent Literature 12: “Scenarios, requirements and KPIs for 5G mobile and wireless system” [Online], April 30, 2013, ICT-317669-METIS / D1.1, [retrieved on October 20, 2013], Internet<https: / / www.metis2020.com / documents / deliverables / > Summary of the invention

[0070] Technical problem to be solved by the invention

[0071] When trying to implement the requirements of the above-mentioned 5G wireless access system with the wireless access method used by LTE, there are items that cannot be met.

[0072] For example, when using high frequencies, at the OFDM subcarrier spacing of 15kHz in the LTE specification, the influence of Doppler shift becomes greater when moving at high speeds, and communication performance deteriorates. In addition, when processing a wide band, the size of the Fast Fourier Transform (FFT) used in OFDM modulation and demodulation becomes larger, causing problems in installation such as circuit scale and software processing volume. Here, the FFT size refers to the number of sample data in the time region used when performing the FFT.

[0073] Furthermore, in the LTE standard, data is processed in subframe (1 ms) units, and therefore in order to meet the low delay requirement of one tenth (1 / 10) of LTE, it is necessary to reduce the size of the radio frame.

[0074] Therefore, without any improvement to the existing LTE wireless access method, it cannot be applied to the 5G wireless access system.

[0075] An object of the present invention is to provide a communication system which can realize data transmission at a relatively high speed and with a relatively small delay and can accommodate various communication terminal devices.

[0076] Technical solutions to technical problems

[0077] The communication system of the present invention includes multiple communication terminal devices and a base station device that constitutes a cell that can wirelessly communicate with the communication terminal devices, and is characterized in that the base station device is configured to set the wireless format of the signal sent and received between the base station device and the communication terminal device according to each of the communication terminal devices.

[0078] Effects of the Invention

[0079] According to the communication system of the present invention, the communication system is configured to include a plurality of communication terminal devices and a base station device constituting a cell capable of wirelessly communicating with the communication terminal devices. The base station device is configured to be able to set the wireless format of the signal transmitted and received between the base station device and the communication terminal device for each communication terminal device. The wireless format is set for each communication terminal device according to the usage mode including the moving speed of the communication terminal device, for example. Therefore, data transmission can be achieved at a relatively high speed and with a relatively small delay, and a communication system that can accommodate various communication terminal devices can be obtained.

[0080] The objects, features, aspects and advantages of the present invention will become more apparent from the following detailed description and accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0081] Figure 1 This is an explanatory diagram showing the structure of a radio frame used in a communication system of the LTE method.

[0082] Figure 2 This is a block diagram showing the overall configuration of a communication system 200 of the LTE scheme being discussed in 3GPP.

[0083] Figure 3 The communication terminal involved in the present invention is Figure 2 A block diagram of the structure of the mobile terminal 202 is shown.

[0084] Figure 4 The base station involved in the present invention is Figure 2 A block diagram of the structure of the base station 203 is shown.

[0085] Figure 5 It is a block diagram showing the structure of the MME involved in the present invention.

[0086] Figure 6 This is a flowchart showing an overview of operations from cell search to standby performed by a communication terminal (UE) in an LTE communication system.

[0087] Figure 7 This is a diagram showing the concept of a cell structure when macro cell eNBs and small cell eNBs coexist.

[0088] Figure 8 This is a diagram showing an example of signals used in Embodiment 1 of the present invention.

[0089] Fig. 9 This is a diagram showing another example of signals used in Embodiment 1 of the present invention.

[0090] Fig.10 This is a diagram showing an example of a signal when signals having different OFDM subcarrier intervals are mixed in a time unit.

[0091] Fig.11 This is a diagram showing an example of a signal when signals having different OFDM subcarrier intervals are mixed in frequency units.

[0092] Fig.12 This is a diagram showing an example of a signal when signals having different OFDM subcarrier intervals are mixed in time units and frequency units.

[0093] Fig.13 This is a diagram showing another example of a signal when signals having different OFDM subcarrier intervals are mixed in time units and frequency units.

[0094] Fig.14This is a diagram showing an example of a format used in Embodiment 2 of the present invention.

[0095] Fig.15 This is a diagram showing an example of the speed-of-light transmission distance with discrete delays caused by direct waves and reflected waves of a communication terminal.

[0096] Fig.16 The diagram shows an example of a resource block into which training sequences are inserted.

[0097] Fig.17 is a diagram showing an example of a resource block into which a training sequence is inserted.

[0098] Fig.18 It is a diagram for explaining a modified example of the second method.

[0099] Fig.19 This is a diagram showing an example of the wireless format of cell #1 and cell #2.

[0100] Fig. 20 This is a diagram showing an example of parameters of the wireless formats of cell #1 and cell #2.

[0101] Fig.21 This is a diagram showing an example of the wireless format of cells #1 to #3.

[0102] Fig. 22 This is a diagram showing an example of parameters of the wireless formats of cells #1 to #3.

[0103] Fig.23 This is a diagram showing a system in which cells of independent and different base stations are adjacent to each other.

[0104] Fig.24 This is a diagram showing a system in which one base station centrally manages multiple cells.

[0105] Fig.25 This is a diagram showing a system in which macro cells and small cells overlap.

[0106] Fig.26 This is a diagram for explaining the timing of changing the data symbol length.

[0107] Fig. 27 This is a diagram showing an example of the insertion ratio of the cell-specific reference signal (CRS).

[0108] Fig.28 This is a diagram showing an example of the insertion interval of the cell-specific reference signal (CRS).

[0109] Fig.29This is a diagram showing an example of the CRS insertion interval and insertion ratio when the OFDM symbol length is different.

[0110] Fig.30 This is a diagram showing an example of a control action in the communication system according to the fifth embodiment.

[0111] Fig.31 This is a diagram showing an example of the TTI period of UE#1 and UE#2.

[0112] Fig.32 This is a diagram showing an example of a HARQ cycle when different TTIs exist in a mixed manner.

[0113] Fig.33 This is a diagram showing an example of data allocation to OFDM symbols within a TTI.

[0114] Fig.34 This is a diagram showing an example of allocation of a synchronization signal (SS) and data.

[0115] Fig.35 This is a diagram showing an example of the arrangement of synchronization signals (SS) in a frequency band.

[0116] Fig.36 is a diagram showing another example of the arrangement of the synchronization signal (SS) in the frequency band.

[0117] Fig.37 This is a flowchart showing the processing steps of the communication terminal related to the synchronization signal detection process.

[0118] Fig.38 This is a diagram showing an example of a method of arranging a synchronization signal (SS) in the frequency direction.

[0119] Fig.39 This is a diagram showing the structure of a communication system according to Embodiment 8 of the present invention.

[0120] Fig.40 This is a block diagram showing the structure of a communication system according to Embodiment 8 of the present invention.

[0121] Fig.41 It is a block diagram showing the structure of the base station transmission processing unit 5101 when the backhaul signal transmission method is used.

[0122] Fig.42 It is a block diagram showing the structure of the base station transmission processing unit 5101 when the dual-link signal transmission method is used.

[0123] Fig.43 This is a block diagram showing the structure of the base station transmission processing unit 5101 when the fronthaul signal transmission method is used.

[0124] Fig.44 It is a block diagram showing the structure of the base station reception processing unit 5102 when the backhaul signal transmission method is used.

[0125] Fig.45 It is a block diagram showing the structure of the base station reception processing unit 5102 when the dual-link signal transmission method is used.

[0126] Fig.46 It is a block diagram showing the structure of the base station reception processing unit 5102 when the fronthaul signal transmission method is used.

[0127] Fig.47 It is a block diagram showing the structure of the base station mode reception processing unit 5105.

[0128] Fig.48 It is a block diagram showing the structure of the mobile terminal mode reception processing unit 5106 when the backhaul signal transmission method is used.

[0129] Fig.49 It is a block diagram showing the structure of the mobile terminal mode reception processing unit 5106 when using the dual-line signal transmission method.

[0130] Fig.50 It is a block diagram showing the structure of the mobile terminal mode reception processing unit 5106 when the fronthaul signal transmission method is used.

[0131] Fig.51 It is a block diagram showing the structure of the base station mode transmission processing unit 5108 when the backhaul signal transmission method is used.

[0132] Fig.52 It is a block diagram showing the structure of the base station mode transmission processing unit 5108 when using the dual-link signal transmission method.

[0133] Fig.53 It is a block diagram showing the structure of the base station mode transmission processing unit 5108 when the fronthaul signal transmission method is used.

[0134] Fig.54 It is a block diagram showing the structure of the mobile terminal mode sending processing unit 5109. DETAILED DESCRIPTION

[0135] Implementation method 1.

[0136] Figure 2 1 is a block diagram showing the overall structure of a communication system 200 of the LTE scheme being discussed in 3GPP. Figure 2The wireless access network is referred to as E-UTRAN (Evolved Universal Terrestrial Radio Access Network) 201. The communication terminal device, i.e., the mobile terminal device (hereinafter referred to as "mobile terminal (User Equipment: UE)") 202 can wirelessly communicate with the base station device (hereinafter referred to as "base station (E-UTRAN NodeB: eNB)") 203, and transmit and receive signals by wireless communication.

[0137] Here, the term "communication terminal device" includes not only mobile terminal devices such as portable cellular phone terminal devices, but also immobile devices such as sensors. In the following description, the term "communication terminal device" may be simply referred to as "communication terminal".

[0138] If the control protocols for the mobile terminal 202, such as RRC (Radio Resource Management) and the user layer, such as PDCP (Packet Data Convergence Protocol), RLC (Radio Link Control), MAC (Medium Access Control), and PHY (Physical layer) are terminated at the base station 203, the E-UTRAN is composed of one or more base stations 203.

[0139] The control protocol RRC between the mobile terminal 202 and the base station 203 performs broadcast, paging, RRC connection management, etc. The states of the base station 203 and the mobile terminal 202 in RRC are RRC_IDLE and RRC_CONNECTED.

[0140] In RRC_IDLE, PLMN (Public Land Mobile Network) selection, system information (SI) broadcasting, paging, cell reselection, movement, 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), neighbor cell measurement, etc. are performed.

[0141] The base station 203 is classified into eNB 207 and Home-eNB 206. The communication system 200 includes an eNB group 203-1 including a plurality of eNBs 207, and a Home-eNB group 203-2 including a plurality of Home-eNBs 206. A system composed of EPC (Evolved Packet Core) as a core network and E-UTRAN 201 as a radio access network is referred to as EPS (Evolved Packet System). EPC as a core network and E-UTRAN 201 as a radio access network are sometimes collectively referred to as a "network".

[0142] 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 an "MME unit") 204 including the MME and the S-GW via an S1 interface, and control information is communicated between the eNB 207 and the MME unit 204. One eNB 207 can be connected to a plurality of MME units 204. The eNBs 207 are connected to each other via an X2 interface, and control information is communicated between the eNBs 207.

[0143] The Home-eNB 206 is connected to the MME unit 204 via the S1 interface, and control information is communicated between the Home-eNB 206 and the MME unit 204. One MME unit 204 is connected to a plurality of Home-eNBs 206. Alternatively, the Home-eNB 206 is connected to the MME unit 204 via the HeNBGW (Home-eNB GateWay: Home-eNB Gateway) 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.

[0144] 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 communicate information via the S1 interface.

[0145] The MME unit 204 and the HeNBGW 205 are upper devices, specifically upper nodes, and control the connection between the eNB 207 and the Home-eNB 206 as base stations and the mobile terminal (UE) 202. The MME unit 204 constitutes the EPC as the core network. The base station 203 and the HeNBGW 205 constitute the E-UTRAN 201.

[0146] Furthermore, the following structure is studied in 3GPP. The X2 interface between Home-eNBs 206 is supported. That is, Home-eNBs 206 are connected to each other via the X2 interface, and control information is communicated between Home-eNBs 206. From the perspective of MME unit 204, HeNBGW 205 can be regarded as Home-eNB 206. From the perspective of Home-eNB 206, HeNBGW 205 can be regarded as MME unit 204.

[0147] Regardless of whether the Home-eNB 206 is connected to the MME unit 204 via the HeNBGW 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.

[0148] The base station 203 may constitute one cell or multiple cells. Each cell has a predetermined range as a range in which communication with the mobile terminal 202 can be performed, i.e., a coverage range, and wireless communication is performed with the mobile terminal 202 within the coverage range. When one base station 203 constitutes multiple cells, each cell is configured to be able to communicate with the mobile terminal 202.

[0149] Figure 3 The mobile terminal involved in the present invention is Figure 2 The structure of the mobile terminal 202 is shown in FIG. Figure 3 2. The transmission processing of the mobile terminal 202 shown in FIG. 2 is described. First, the control data from the protocol processing unit 301 and the user data from the application unit 302 are stored in the transmission data buffer unit 303. The data stored in the transmission data buffer unit 303 is transmitted to the encoder unit 304 and subjected to encoding processing such as error correction. There may also be data that is directly output from the transmission data buffer unit 303 to the modulation unit 305 without performing encoding processing. The data after the encoding processing by the encoder unit 304 is modulated in the modulation unit 305. The modulated data is converted into a baseband signal, and then output to the frequency conversion unit 306, and converted into a wireless transmission frequency. After that, the transmission signal is sent from the antenna 307 to the base station 203.

[0150] In addition, the receiving process of the mobile terminal 202 is performed as follows. The wireless signal from the base station 203 is received by the antenna 307. The received signal is converted from the wireless receiving frequency to a baseband signal by the frequency conversion unit 306, and demodulated in the demodulation unit 308. The demodulated data is transmitted to the decoder unit 309, and decoding processes such as error correction are performed. 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. The series of processes of the mobile terminal 202 is controlled by the control unit 310. Therefore, although in Figure 3 Although omitted in the figure, the control unit 310 is connected to each of the units 301 to 309.

[0151] Figure 4 The base station involved in the present invention is Figure 2 The structure of the base station 203 is shown in FIG. Figure 4 4. The transmission processing of the base station 203 shown in FIG. 4 is described. The EPC communication unit 401 performs data transmission and reception between the base station 203 and the EPC (MME unit 204, etc.), the HeNBGW 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.

[0152] The data stored in the transmission data buffer unit 404 is transmitted to the encoder unit 405 and subjected to 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 being subjected to encoding processing. The encoded data is modulated in the modulation unit 406. The modulated data is converted into a baseband signal and then output to the frequency conversion unit 407 and converted into a wireless transmission frequency. Thereafter, the transmission signal is transmitted to one or more mobile terminals 202 using the antenna 408.

[0153] In addition, the receiving process of the base station 203 is performed as follows. The wireless signal from one or more mobile terminals 202 is received through the antenna 408. The received signal is converted from the wireless receiving frequency to the baseband signal by the frequency conversion unit 407, and the demodulation process is performed in the demodulation unit 409. The demodulated data is transmitted to the decoder unit 410, and the decoding process such as error correction is performed. The control data in the decoded data is transmitted to the protocol processing unit 403 or the EPC communication unit 401, and 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 in Figure 4Although omitted in FIG. 4 , the control unit 411 is connected to each of the units 401 to 410 .

[0154] Figure 5 It is a block diagram showing the structure of the MME involved in the present invention. Figure 5 The above Figure 2 The structure of MME204a included in the MME unit 204 shown. The PDNGW communication unit 501 performs data transmission and reception between MME204a and PDNGW. The base station communication unit 502 performs data transmission and reception between MME204a and the base station 203 via the S1 interface. In the case where the data received from the PDNGW is user data, the user data is transmitted from the PDNGW communication unit 501 to the base station communication unit 502 via the user layer communication unit 503, and is sent to one or more base stations 203. In the case where 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 PDNGW communication unit 501 via the user layer communication unit 503, and is sent to the PDNGW.

[0155] When the data received from the PDN GW is control data, the control data is transferred 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 transferred from the base station communication unit 502 to the control plane control unit 505.

[0156] The HeNBGW communication unit 504 is provided in the presence of the HeNBGW 205, and performs data transmission and reception between the MME 204a and the HeNBGW 205 via the interface (IF) according to the information type. The control data received from the HeNBGW communication unit 504 is transmitted from the HeNBGW communication unit 504 to the control plane control unit 505. The processing result 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 the S1 interface, and is sent to one or more HeNBGW 205 via the HeNBGW communication unit 504.

[0157] 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 manages the SAE (System Architecture Evolution) bearer, etc. The idle state mobility management unit 505-3 performs mobility management in the standby state (also called the idle state; LTE-IDLE state, or simply idle), generates and controls paging signals in the standby state, and adds, deletes, updates, retrieves, and manages the tracking area list of one or more mobile terminals 202 under coverage.

[0158] MME204a distributes 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 idle state and the active state. MME204a starts the paging protocol by sending a paging message to the cell belonging to the tracking area (Tracking Area) to which the UE is logged in (registered). The management of the CSG, the management of the CSG_ID, and the whitelist management of the Home-eNB206 connected to the MME204a can be performed by the idle state mobility management unit 505-3.

[0159] Next, an example of a cell search method in a communication system is shown. Figure 6 This is a flowchart showing an overview of the cell search and standby operation performed by a communication terminal (UE) in an LTE communication system. When the mobile terminal starts the cell search, it uses the first synchronization signal (P-SS) and the second synchronization signal (S-SS) sent from the surrounding base stations in step ST601 to synchronize the time slot timing and frame timing.

[0160] P-SS and S-SS are collectively referred to as synchronization signals (SS). Synchronization codes corresponding to the PCIs assigned to each cell are allocated to the synchronization signal (SS). Consider setting the number of PCIs to 504. These 504 PCIs are used to achieve synchronization, and the PCI of the synchronized cell is detected (specified).

[0161] Next, in step ST602, the reference signal (reference signal: RS) sent from the base station to each cell, i.e., the cell-specific reference signal (Cell-specific Reference Signal: CRS), is detected for the synchronized cell, and the RS received power (Reference Signal Received Power: RSRP) is measured. The reference signal (RS) uses a code that corresponds to the PCI one-to-one. This code can be used to obtain correlation and separate from other cells. By deriving the RS code for the cell based on the PCI specified in step ST601, the RS can be detected and the RS received power can be measured.

[0162] Next, in step ST603, a cell with the best RS reception quality, for example, a cell with the highest RS reception power, that is, an optimal cell, is selected from the one or more cells detected up to step ST602.

[0163] Next, in step ST604, the PBCH of the best cell is received to obtain the broadcast information, i.e., the BCCH. The MIB (Master Information Block) containing the cell structure information is mapped to the BCCH on the PBCH. Therefore, by receiving the PBCH and obtaining the BCCH, the MIB can be obtained. The MIB information includes, for example, the downlink system bandwidth (dl-bandwidth for short), the number of transmission antennas, and the system frame number (SFN). The downlink system bandwidth is also referred to as the transmission bandwidth configuration.

[0164] Next, in step ST605, the DL-SCH of the cell is received based on the cell structure information of the MIB, and the SIB (System Information Block) 1 in the broadcast information BCCH is obtained. SIB1 contains information related to accessing the cell, information related to cell selection, and scheduling information of other SIBs (SIBk; k≥2 integer). In addition, SIB1 contains the Tracking Area Code (TAC).

[0165] Then 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 that the communication terminal has saved. The tracking area list is also called the TAI list. TAI is identification information for identifying the 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.

[0166] If the result of the comparison in step S606 is that the TAC received in step ST605 is the same as the TAC included in the tracking area list, the communication terminal enters the standby action in the 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 MME, etc. to change the tracking area through the cell to perform TAU (Tracking Area Update).

[0167] 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 held by the communication terminal based on the received tracking area list. Thereafter, the communication terminal enters standby action in the cell.

[0168] The popularity of smartphones and tablet computers has led to an explosive growth in the volume of cellular wireless communications, causing concerns about the shortage of wireless resources in the world. In response, in order to improve the efficiency of frequency utilization, the miniaturization of cells and spatial separation are being explored.

[0169] In the existing cell structure, a cell formed by an eNB has a wide coverage area. Conventionally, cells are formed so as to cover a certain area using the wide coverage areas of a plurality of cells formed by a plurality of eNBs.

[0170] When the cell is miniaturized, the cell formed by the eNB has a narrower coverage area than the coverage area of ​​the cell formed by the existing eNB. Therefore, as in the prior art, a large number of eNBs with miniaturized cells are required to cover a certain area compared to the existing eNBs.

[0171] In the following description, a cell with a large coverage area, such as a cell formed by an existing eNB, is referred to as a "macro cell", and an eNB constituting a macro cell is referred to as a "macro eNB". In addition, a cell with a small coverage area, such as a cell that has been miniaturized, is referred to as a "small cell", and an eNB constituting a small cell is referred to as a "small eNB".

[0172] The macro cell eNB may be, for example, the “Wide Area Base Station” described in Non-Patent Document 8.

[0173] Small cell eNBs may be, for example, low-power nodes, local area nodes, and hotspots. Small cell eNBs may be pico eNBs constituting pico cells, femto eNBs constituting femto cells, HeNBs, RRHs (Remote Radio Heads), RRUs (Remote Radio Units), RREs (Remote Radio Equipment), or RNs (Relay Nodes). Small cell eNBs may be "local area base stations" or "home base stations" as described in non-patent document 8.

[0174] Figure 7 This is a diagram showing the concept of a cell structure when macro eNBs and small eNBs coexist. A macro cell composed of macro eNBs has a relatively wide coverage area 701. A small cell composed of small eNBs has a narrower coverage area 702 than the coverage area 701 of the macro eNB (macro cell).

[0175] When multiple eNBs exist in a mixed manner, the coverage of a cell formed by a certain eNB may be included in the coverage of a cell formed by other eNBs. Figure 7 In the cell structure shown, as shown by reference numerals "704" or "705", a coverage area 702 of a small cell formed by a small cell eNB is sometimes included in a coverage area 701 of a macro cell formed by a macro cell eNB.

[0176] As shown by reference numeral 705, coverage areas 702 of multiple, for example, two small cells may be included in coverage area 701 of one macro cell. A mobile terminal (UE) 703 is included in the coverage area 702 of the small cell and communicates via the small cell.

[0177] exist Figure 7 In the cell structure shown, as shown by reference numeral "706", there is a situation 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 complicatedly overlapped.

[0178] In addition, as shown 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.

[0179] Furthermore, as shown by reference numeral "708", the following situation may occur: the coverage area 702 of multiple small cell cells formed by multiple small cell eNBs is formed within the coverage area 701 of one macro cell cell formed by one macro eNB.

[0180] In addition, as a fifth-generation wireless access method aimed at being commercialized between 2018 and 2020, as disclosed in Non-Patent Document 12, a method that accommodates various communication terminals is being considered.

[0181] For example, in the DenseUrban scheme (TC2) described in ICT-317769-METIS / D6.11 (Chapter 9.2) and Non-Patent Literature 12 (Chapter 8), for each communication terminal, the downlink needs to be 300 Mbps and the uplink needs to be 60 Mbps. Taking the number of communication terminals into account, the communication capacity per unit area needs to be 700 Gbps / km. 2 The moving speed when used indoors needs to be about 0km / h, and the moving speed when used outdoors needs to be 3-50km / h. The allowed delay time for each web page when browsing the web needs to be 0.5 seconds (s), and the allowed delay time when starting augmented reality needs to be 2-5ms.

[0182] In addition, in the high-speed mobile terminal scheme (TC8) described in Non-Patent Document 12 (Chapter 14), for each communication terminal, the downlink needs to be 100 Mbps and the uplink needs to be 20 Mbps, and the communication capacity per unit area taking into account the number of communication terminals needs to be 60 Gbps / km 2 , the moving speed needs to be 350km / h, and the allowed delay time needs to be 10ms.

[0183] Therefore, the requirements vary depending on the usage mode, so in order to improve the frequency utilization efficiency, the best wireless format for each communication method is needed. However, in the current LTE / LTE-A wireless format, the interval between OFDM subcarriers transmitted simultaneously is fixed, which has the problem of deteriorating the frequency utilization efficiency depending on the usage mode.

[0184] In order to solve the above problems, the present embodiment discloses the following technology: when the base station restarts communication with the communication terminal, it receives the notification of the moving speed of the communication terminal and sets the OFDM subcarrier spacing corresponding to the moving speed. By using this technology, the frequency utilization efficiency can be improved.

[0185] The base station mentioned here can be an eNB (evolved NodeB) of 3GPP, or a MeNB (Master eNB) or SeNB (Secondary eNB) in dual connection. In addition, it can also be a device called a wireless relay node (RN), a remote radio head (RRH), or a concentrator. In addition, it can also be a component carrier CC (CC) in carrier aggregation.

[0186] In Doppler phasing specific to a moving object, it is known that a carrier offset is generated according to the moving speed. Let the moving speed of the moving object be v, the carrier frequency be f, and the speed of light be c, and the carrier offset is expressed by the following equation "v×f / c". That is, the faster the moving speed, the larger the carrier offset.

[0187] Figure 8 This is a diagram showing an example of signals used in Embodiment 1 of the present invention. Fig. 9 This is a diagram showing another example of signals used in Embodiment 1 of the present invention. Figure 8 As an example, a signal when the OFDM subcarrier spacing is K1 (Hz) is shown. Fig. 9 In FIG. 1 , for comparison, the signal when the OFDM subcarrier spacing is twice K1, that is, K2 (Hz) is shown. Figure 8 and Fig. 9 In , the training sequence signal is shaded.

[0188] Figure 8 (a) and Fig. 9 The horizontal axis of (a) represents frequency f, and the vertical axis represents time t. Figure 8 (b) and Fig. 9 The horizontal axis of (b) represents frequency f, and the vertical axis represents power P. Figure 8 and Fig. 9In either case, a training sequence signal of the same energy, i.e., the same area in the figure, such as a reference signal, is sent for synchronous detection. At this time, when the OFDM subcarrier spacing is K1 (Hz), the training sequence signal spacing becomes J1, but when the OFDM subcarrier spacing is twice K1, i.e., K2 (Hz), the training sequence signal spacing becomes half of J1 (J1 / 2), i.e., J2.

[0189] Therefore, it can be seen that the larger the OFDM subcarrier spacing is, the shorter the training sequence signal spacing is, and the easier it is to detect the temporal variation of the carrier offset, so it is resistant to high-speed movement, that is, the receiving side can demodulate even at high-speed movement.

[0190] By utilizing this property, the OFDM subcarrier spacing is reduced for communication terminals moving at low speeds such as indoors, and is increased for communication terminals moving at high speeds such as on Shinkansen trains.

[0191] In addition, in the case of a communication terminal such as a sensor with a bandwidth of about 125 bytes / 5 minutes (see ICT-317669-METIS / D6.14.11), if the OFDM subcarrier spacing is reduced, the frequency band of the transmission amplifier of the communication terminal can be reduced, thereby achieving low power consumption.

[0192] In this embodiment, as described above, signals having various OFDM subcarrier intervals can be mixed. Fig.10 This is a diagram showing an example of a signal when signals having different OFDM subcarrier intervals are mixed in a time unit. Fig.10 The horizontal axis represents frequency f, and the vertical axis represents time t. In the range of time t9 to time t14, the OFDM subcarrier spacing is K1 (Hz), and in the remaining time range, the OFDM subcarrier spacing is K2 (Hz), which is twice K1.

[0193] Through Fig.10 As shown, signals with different OFDM subcarrier intervals are mixed in a time unit, so that modulation and demodulation of OFDM signals can be realized with a single FFT size in time. This can reduce the scale or processing capacity of the hardware of the communication terminal and the base station.

[0194] Fig.11 This is a diagram showing an example of a signal when signals having different OFDM subcarrier intervals are mixed in frequency units. Fig.11 The horizontal axis of (a) represents frequency f, and the vertical axis represents time t. Fig.11 (b) and Fig.11The horizontal axis of (c) represents frequency f, and the vertical axis represents power P. In the frequency range of f3 to f6, the OFDM subcarrier spacing is K1 (Hz), and in the remaining frequency range, the OFDM subcarrier spacing is K2 (Hz), which is twice K1.

[0195] Through Fig.11 As shown in the figure, signals with different OFDM subcarrier spacings are mixed in the frequency unit, so that the modulation and demodulation of the OFDM signal can be processed in the same way for each frequency. At this time, if the mixed OFDM subcarrier spacings are n times or one-nth (1 / n) times each other, the OFDM subcarriers configured at the separated frequencies can be processed by the same Inverse Fast Fourier Transform (IFFT) or Fast Fourier Transform (FFT). As a result, the scale or processing amount of the hardware can be reduced.

[0196] In addition, it is possible to convert the power of f3+f4 and f5+f6 without allocating the power of f3+f4 and f5+f6. Fig.11 The IFFT including the dotted line part is also included and sent. Similarly, as a receiving process, it is possible to Fig.11 The dotted part of is also included in the FFT, and the data of f3+f4 and f5+f6 are discarded.

[0197] In addition, at the boundary of adjacent and different OFDM subcarrier spacings, for the frequency where inter-symbol interference occurs, the method of not allocating data is effective. The signal of f1+f2 interferes with the signal of f3. That is, at the frequency of Fig.11 At the peak of f3 shown by the arrow, the power of the signal of f1+f2 does not become 0, and becomes interference power P1 for f3. Therefore, it is also effective not to use f3 or not to use f1+f2. In order to reduce the unusable frequency, it is more preferable not to use f3 with a small OFDM subcarrier spacing.

[0198] In addition, even if interference occurs at the boundary of adjacent, different OFDM subcarrier spacings, it is effective to simplify processing by sending the same data as when not adjacent. This is effective when the signal power of f3 is greater than the interference power, or when the receiving side is equipped with an interference removal function.

[0199] Fig.12 This is a diagram showing an example of a signal when signals having different OFDM subcarrier intervals are mixed in time units and frequency units. Fig.12 The horizontal axis represents frequency f, and the vertical axis represents time t. Fig.12 An example is shown in which signals having different OFDM subcarrier intervals are mixed in the configuration of the time unit and the frequency unit for each communication terminal.

[0200] The OFDM subcarrier spacing of resource blocks (hereinafter sometimes referred to as "RB") 11 and 23 is twice K1, that is, K2 (Hz), and "6 subcarriers × 14 OFDM symbols" is set as one resource block. The other OFDM subcarrier spacing is K1 (Hz), and "12 subcarriers × 7 OFDM symbols" is set as one resource block. Fig.12 In the example shown, two types of resource blocks exist in a mixed state, but three or more types of resource blocks may exist in a mixed state.

[0201] Here, "resource block" does not include information of multiple communication terminals, but is the minimum unit used by a communication terminal for communication. Therefore, a resource block is the minimum unit of data including a signal of a training sequence for transmission path estimation on the receiving side. In addition, a resource block can also be the minimum unit for transmitting error correction coded data. In addition, a resource block can also be the minimum unit for delivery confirmation of ARQ (Automatic Repeat reQuest), HARQ (Hybrid ARQ), etc. based on the qualification of CRC (Cyclic Redundancy Check).

[0202] Fig.13 This is a diagram showing another example of a signal when signals having different OFDM subcarrier intervals are mixed in time units and frequency units. Fig.13 The horizontal axis represents frequency f, and the vertical axis represents time t. Fig.12 The example in which the sum of the frequency widths K1 and K2 of each resource block and the sum of the OFDM symbol length (SL) are the same is shown, but it is also possible to Fig.13 As shown, a portion corresponding to the amount of data generated by each event is defined as a resource block.

[0203] As an example of the amount of data generated per event, 125 bytes is given as one block of data sent by the sensor, and as an example of a resource block corresponding thereto, for example, 4 subcarriers×14 OFDM symbols, 1 subcarrier×7 OFDM symbols, etc. are given.

[0204] For each resource block defined as described above, OFDM subcarrier spacing is appropriately allocated in response to changes in the moving speed of a communication terminal such as a mobile terminal, thereby flexibly coping with time and frequency and improving frequency utilization efficiency.

[0205] In order to achieve the above, in this embodiment, in a communication terminal such as a mobile terminal, the moving speed of the device is measured using GPS (Global Positioning System), and the base station uses the measurement results received from the communication terminal through RRC to determine the OFDM subcarrier spacing. Only the location information such as GPS can be notified to the base station from the communication terminal such as a mobile terminal, and the moving speed is calculated in the base station based on the difference with the previous location information. In addition, the round-trip time (Round-Trip Time) can also be measured in the base station, for example, the round-trip time of the random access signal or the angle information of the incoming wave is used, and the moving speed is calculated based on the change amount.

[0206] Alternatively, the following method is also effective: in the communication terminal, the Doppler frequency is measured based on the phase rotation amount of the training sequence, and the measured Doppler frequency is reported to the base station. In the base station, the OFDM subcarrier spacing is determined using the measurement result received from the communication terminal through RRC or the like. Alternatively, the following method is also effective: in the communication terminal, the phase rotation amount of the training sequence itself or its average value within a specified time such as one time slot or one subframe is reported to the base station.

[0207] Alternatively, whether or not the communication terminal can cope with high-speed movement is set as the communication terminal performance (hereinafter sometimes referred to as "UE performance (capability)"). Even if the communication terminal is not actually capable of high-speed movement, but the UE performance is capable of high-speed movement, the base station sets the OFDM subcarrier spacing to be larger. Similarly, when the UE performance is low speed or cannot move, the OFDM subcarrier spacing is set to be smaller.

[0208] It is preferred to classify the above-mentioned moving speed, Doppler frequency, training sequence phase rotation amount in a specified time, or supported moving speed (UE capability) into several stages for reporting. In this way, the amount of information can be reduced. For example, it is also effective to pre-classify into three stages: high speed [Shinkansen / Tram / Car], low speed [Pedestrian], and fixed. Alternatively, it is also effective to set it as two stages: moving and fixed.

[0209] The OFDM subcarrier spacing used for communication is determined based on the reported value, and can be set to an OFDM subcarrier spacing that is proportional to the actual moving speed or the inverse of the supported moving speed, or a value close thereto.

[0210] In addition, for signals such as CRS (Cell-specific Reference Signal) used for monitoring and common control of surrounding cells of the communication terminal, a fixed OFDM subcarrier spacing is set regardless of the moving speed of the communication terminal. This makes it possible to transmit and receive even without exchanging control information between the communication terminal and the base station, which is effective.

[0211] Similar to the above signals for monitoring and common control of surrounding cells of communication terminals, the following method is also effective, namely: regardless of the moving speed, the common channel uses a fixed OFDM subcarrier spacing with a longer subcarrier spacing, and the dedicated channel can change the OFDM subcarrier spacing according to the moving speed.

[0212] In addition, it is also effective to set the following method, namely: in a dedicated channel, regardless of the moving speed, the common channel (PDCCH in LTE) attached to the dedicated channel uses a fixed OFDM subcarrier spacing with a longer subcarrier spacing, and the channel of the data part (PDSCH in LTE) can be changed according to each communication terminal.

[0213] Furthermore, it is also effective to assume that a fixed OFDM subcarrier spacing with a longer subcarrier spacing is used for a broadcast channel (PMCH in LTE) regardless of the mobile speed.

[0214] The OFDM subcarrier spacing is set relatively large for monitoring and common control of surrounding cells of the communication terminal, and is set to an OFDM subcarrier spacing corresponding to high-speed movement, for example, to ensure communication quality. This is effective in enabling transmission and reception regardless of the movement speed.

[0215] In addition, the OFDM subcarrier spacing corresponding to the OFDM subcarrier spacing of slow movement is relatively small, but it can also be as follows. By increasing the transmission power, or using a modulation method with a small modulation degree such as BPSK (Binary Phase Shift Keying), or setting the error correction capability of the error correction code to a higher level, such as reducing the coding rate, or the coding gain of the Hadamard code and Zadoff-Chu, the communication quality of the communication terminal moving at high speed can be compensated. In this way, the OFDM subcarrier spacing can be reduced, and the power consumption of the communication terminal can be reduced.

[0216] Next, a method for a communication terminal, for example, a mobile terminal, to notify a base station of at least one of its own position, the above-mentioned moving speed, the Doppler frequency, and the training sequence phase rotation amount in a predetermined time will be described.

[0217] When initially connecting or starting communication with a base station at a mobile destination due to handover, the communication terminal sends a synchronization signal to the base station, such as the random access preamble in Chapter 10.1.5.1 and Chapter 10.1.5.2 of Non-Patent Document 1 (3GPP TS36.300).

[0218] When the base station receives the synchronization signal transmitted by the communication terminal, it transmits a signal notifying the reception of the synchronization signal as a random access response, and corrects the transmission timing of the communication terminal so that the communication terminal can transmit while the base station is on standby.

[0219] The communication terminal that receives the signal sent by the base station sends an RRC (Radio Resource Control) connection request as control information for enabling communication dedicated to the communication terminal. The RRC connection request may include the moving speed, Doppler frequency, and training sequence phase rotation amount in a predetermined time of the communication terminal.

[0220] The base station that receives the RRC connection request takes into account the radio resource status of the base station for other communication terminals, such as whether there are idle resources, and then sends a radio format change instruction corresponding to the moving speed, such as an OFDM subcarrier spacing change instruction. After sending the change instruction, the base station starts to transmit and receive using the new radio format after receiving a response of change instruction approval from the communication terminal.

[0221] A communication terminal may be in a situation where it is simultaneously communicating with other base stations such as CoMP and cannot change the wireless format in order to transmit the same signal. Therefore, the communication terminal considers the communication status and returns a response of approval or denial of the change instruction to the base station.

[0222] In the above steps, the wireless format can be changed reliably, but the number of exchanges between the base station and the communication terminal increases. In order to avoid the above situation, once the base station sends a wireless format change instruction to the communication terminal, the base station can start to use the wireless format after the change instruction for transmission and reception. In this case, it is unclear whether the communication terminal can receive the change instruction from the base station, and there is also a case where the communication terminal does not agree to the change even if it receives it depending on the communication status of the communication terminal.

[0223] Therefore, the following method is effective: setting a timer, and returning to the original wireless format for transmission and reception when communication cannot be established after the wireless format is changed. Specifically, it is effective to set the timer to measure the following time: after the base station sends a wireless format change indication to the communication terminal, the change approval message (RRC) after the wireless format change is sent from the communication terminal to the base station using the new wireless format, until the base station can receive the change approval message.

[0224] In addition, as another example of the above example, the process until receiving the random access response is the same as the above example, but the RRC connection request after receiving the random access response may include a change in the wireless format calculated by the communication terminal based on the moving speed, Doppler frequency, the training sequence phase rotation amount at a specified time, etc.

[0225] In the above random access example, a method of notifying at least one of the position, moving speed, Doppler frequency, and the training sequence phase rotation amount at a predetermined time of the communication terminal by using the exchange with the communication terminal is shown, but it may also be as follows. For example, when a handover request (Handover Request) is sent from the mobile source base station to the mobile destination base station via the X2 interface, at least one of the position, moving speed, Doppler frequency, and the training sequence phase rotation amount at a predetermined time of the communication terminal or a wireless format determined thereby, such as an OFDM symbol interval, may be notified.

[0226] The notification may be made by using a handover requirement (Handover Required) via the S1 interface, that is, via the MME, instead of via the X2 interface. In addition, the notification may be made by using a handover request (Handover Request) via the Xn interface in dual connectivity.

[0227] In the base station of the mobile destination, when setting a wireless channel as a random access response to a synchronization signal sent by a communication terminal to the base station of the mobile destination, the setting value of each physical channel, specifically, the setting value of the physical configuration, can be set to be the wireless format indicated by the handover request (Handover Request) or the handover requirement (Handover Required) notified from the base station of the mobile source, such as the OFDM symbol interval. At this time, the base station of the mobile destination takes into account the wireless resource status of the base station for other communication terminals, such as whether there is free resource, and notifies the indicated wireless format if there is free resource.

[0228] Next, an example of measurement configuration is shown. When a base station and a communication terminal communicate, a method is also effective in which the base station transmits a measurement configuration (RRC) and the communication terminal transmits a measurement report (RRC) according to the configuration.

[0229] The communication terminal reports at least one of the position, moving speed, Doppler frequency and phase rotation amount of the training sequence at a predetermined time of the device by using the measurement report. The base station receiving the above content takes into account the wireless resource status of the base station for other communication terminals, such as whether there are idle resources, and then sends a wireless format change instruction corresponding to the moving speed, such as reconfiguration.

[0230] After receiving the change indication, the communication terminal considers the communication status with other base stations, such as whether CoMP is performed, and sends a change indication approval response without communicating with other base stations or using the same wireless format, and starts to transmit and receive using the new wireless format. After receiving the change indication approval response, the base station starts to transmit and receive using the new wireless format.

[0231] After sending the change instruction, the base station starts to transmit and receive using the new wireless format after receiving a change instruction approval response from the communication terminal. After receiving the change instruction approval response, the communication terminal starts to transmit and receive using the new wireless format.

[0232] Next, an example of sending a request to change the wireless format from a communication terminal is shown. The communication terminal can detect the moving speed based on the position of the device, the moving speed, the Doppler frequency, and the phase rotation amount of the training sequence at a predetermined time, and send a request to change the wireless format, such as the OFDM symbol interval, separately from the random access and measurement configuration.

[0233] After receiving the change request, the base station considers the wireless resource status of the base station for other communication terminals, such as whether there are idle resources. If there are idle resources, the base station sends a change approval response and starts to use the new wireless format for transmission and reception. After receiving the change approval response, the communication terminal starts to use the new wireless format for transmission and reception.

[0234] In addition, the above shows an example of indicating a change in the wireless format such as OFDM subcarrier spacing by RRC, but in order to switch at a higher speed, it is also effective to use MAC to send and receive the type of wireless format. In addition, it is also effective to use physical signaling to notify the type of wireless format accompanying the transmitted data.

[0235] The above describes an example in which a wireless format, for example, an OFDM subcarrier spacing, is set for each communication terminal. However, it is also effective to set a wireless format for each communication terminal group.

[0236] It is also effective to group the communication terminals into three types: high speed, low speed, and fixed as described above. For example, the following method is also effective: three wireless formats are notified in the settings of each physical channel notified when the channel is established, and the communication terminal switches the wireless format to be used according to the moving speed of the device, and the base station blindly decodes according to the three wireless formats and uses the wireless format that is OK with CRC.

[0237] Alternatively, the following method is also effective: three wireless formats are notified in the settings of each physical channel notified when the channel is established, and when the communication terminal switches the wireless format according to the moving speed of the device, the number of the wireless format used is attached to the data using physical signaling. In this case, it is effective to set the wireless format to be fixed by physical signaling.

[0238] According to the present embodiment described above, the base station device is configured to be able to set the wireless format of the signal transmitted and received between the base station device and the communication terminal device for each communication terminal device. The wireless format is set for each communication terminal device based on the usage mode including the moving speed of the communication terminal device, for example. Therefore, data transmission can be achieved at a relatively high speed and with a relatively small delay, and a communication system that can accommodate various communication terminal devices can be obtained.

[0239] In this embodiment, the wireless format is set for each communication terminal device based on the usage mode including the moving speed of the communication terminal device. Thus, an appropriate wireless format corresponding to the usage mode of each communication terminal device can be set. Therefore, a communication system that can realize data transmission at a higher speed and with less delay can be obtained.

[0240] In this embodiment, the base station apparatus and the communication terminal apparatus perform wireless communication using orthogonal frequency division multiplexing (OFDM). The signal transmitted and received between the base station apparatus and the communication terminal apparatus includes a wireless format in which at least one of the OFDM symbol length (SL) and the cyclic prefix (CP) length (CP length: CPL) are different. As a result, data transmission can be achieved at a relatively high speed and with a relatively small delay as described above, and a communication system that can accommodate various communication terminal apparatuses can be achieved with a simple result.

[0241] Implementation method 2.

[0242] When the distance between the communication terminal and the base station is short, the CP length (CPL) of the OFDM access method can be shortened. In addition, when the spread of delay dispersion in the transmission path between the communication terminal and the base station is small, the CP length can be shortened.

[0243] In the fifth generation of wireless access, which aims to be commercialized between 2018 and 2020, in order to achieve wideband, it is necessary to use microwave (SHF) bands to millimeter wave (Extra High Frequency: EHF) bands, which are estimated to be unused frequencies. As the frequency increases, the transmission loss increases. In addition, in order to increase the communicable capacity per unit area, it is also necessary to further reduce the service area of ​​the base station. Therefore, when OFDM is used in the fifth generation, it is possible to shorten the CP length according to the above conditions.

[0244] However, a technology has also been studied in which a base station with a large capacity and a large cell radius is expected to be required in a rural area with a small population, such as a rural area, so that transmission can be as far as possible using, for example, a multi-element antenna.

[0245] In addition, if the carrier frequency becomes higher, the OFDM subcarrier spacing needs to be set longer than LTE / LTE-A to ensure tolerance to Doppler frequency. In other words, the OFDM symbol length is the reciprocal of the OFDM subcarrier spacing, so the OFDM symbol length needs to be shortened. Therefore, the overhead of the CP length will greatly affect the frequency utilization efficiency.

[0246] Furthermore, if the CP length is too short, the following problems may occur: (1) interference may occur between code elements, deteriorating communication quality; (2) when the communication terminal operates in a low power consumption mode such as discontinuous reception, insufficient synchronization accuracy may cause communication quality to deteriorate.

[0247] As described above, in the process of considering various usage modes, in the current LTE / LTE-A wireless format, the CP length of the downlink PDSCH transmitted simultaneously is fixed in one cell. In this case, for example, the communication terminal detects the CP length aimlessly using the second synchronization signal S-SS transmitted from the base station. When the downlink CP length is fixed in one cell as described above, there is a possibility that the communication quality or frequency utilization efficiency is greatly deteriorated.

[0248] As a technique for preventing the above-mentioned deterioration, the present embodiment discloses a technique in which, when the OFDM access method is adopted, signals with different CP lengths are used for each communication terminal according to the usage method. By using this technique, the frequency utilization efficiency can be improved.

[0249] Fig.14 This is a diagram showing an example of a format used in Embodiment 2 of the present invention. Fig.14 The horizontal axis represents frequency f, and the vertical axis represents time t. Fig.14 An example is shown in which a communication terminal uses resource blocks with different CP lengths according to the distance from the base station. Fig.15 This is a diagram showing an example of the light transmission distance with discrete delays caused by a direct wave (DW) and a reflected wave (RW) at a communication terminal.

[0250] like Fig.14 As shown, resource block (RB) 1 is composed of 8 subcarriers × 11 OFDM symbols = 88 OFDM symbols. When the reciprocal of the clock frequency, i.e., the clock period Ts, is set to 1 / 245.76MHz, if the OFDM subcarrier interval is set to 120kHz, then, for example, the OFDM symbol length (SL) is 2048Ts (=245.76MHz / 120kHz), the CP length (CPL) at the beginning of the resource block is 768Ts, the other CP lengths (CPL) are 128Ts, and the total resource block is 24576Ts = 0.1ms.

[0251] The supported delay dispersion is equal to the minimum CP length, so 128Ts = 0.52μs, which is a format that can be used up to about 150m at the speed of light. Fig.15 The discrete light transmission distance caused by the delay of the direct wave (DW) and reflected wave (RW) of the communication terminal A (UEA) shown becomes the distance between the communication terminal A (UEA) and the base station (BS), so the target supported cell radius can be considered as 150m. Fig.14 Resource block (RB) 1 shown is used for a communication terminal present at a distance closer than 150 m.

[0252] In addition, resource block (RB) 2 is composed of 8 subcarriers × 10 OFDM symbols = 80 OFDM symbols, the OFDM symbol length (SL) is 2048Ts, the starting CP length (CPL) of the resource block is 512Ts, and the other CP lengths (CPLs) are 384Ts. The total resource block is 24576Ts = 0.1ms.

[0253] The supported delay dispersion is equal to the minimum CP length, so 384Ts = 1.56μs, which is a format that can be used up to about 450m at the speed of light. Fig.15 The discrete light transmission distance caused by the delay of the direct wave (DW) and reflected wave (RW) of the communication terminal B (UEB) shown becomes the distance between the communication terminal B (UEB) and the base station (BS), so the target supported cell radius can be considered as 450m. Fig.14 Resource block (RB) 2 is shown for communication terminals present at a distance closer than 450 m.

[0254] Therefore, if an appropriate resource block structure is adopted according to the distance between the communication terminal and the base station, the amount of data that can be transmitted in resource block (RB) 1 can be increased by 10% even with the same resource block size, compared to the case where only resource block (RB) 2 is used uniformly.

[0255] In the present embodiment as described above, resource blocks of two CP lengths are transmitted by changing the frequency, but the CP lengths of resource blocks may be three or more. In addition, resource blocks of CP lengths that differ in time may be used.

[0256] also, Fig.14 In the example of the format, the CP length (CPL) and the OFDM symbol length (SL) are both integer multiples of 128Ts. This corresponds to 245.76MHz / 1.92MHz=128, so it means that it is an integer multiple of 1.92MHz, the sample clock of the communication terminal with a bandwidth of 1.4MHz under LTE (hereinafter sometimes referred to as the "reference clock"). In addition, this also means that it is an integer multiple of 7.68MHz, the sample clock of 7.68MHz, the sample clock of 15.36MHz, and the sample clock of 30.72MHz, the sample clock of 30.72MHz, the sample clock of 5MHz bandwidth.

[0257] It can be seen that by using Fig.14 The format shown can produce a dual-mode communication terminal of LTE / LTE-A with a single clock source, thereby achieving low cost of the communication terminal.

[0258] The following method is effective as a method for determining the distance between the base station and the communication terminal.

[0259] For example, the communication terminal notifies the base station of the location information of the GPS mounted on the communication terminal. The base station calculates the distance between the base station and the communication terminal based on the difference between the location information of the base station written into the memory in the base station when the base station is installed or the memory in the device for maintaining and monitoring the base station and the location information of the GPS notified by the communication terminal. Alternatively, the base station calculates the distance between the base station and the communication terminal based on the difference between the location information of the GPS possessed by the base station and the location information of the GPS notified by the communication terminal.

[0260] For example, a method of converting the deviation from the specified time into a distance using a transmission signal from a communication terminal is also effective. In this case, the base station receives a random access signal and converts the deviation from the specified time into a distance, similar to the control of timing advance in LTE / LTE-A.

[0261] In addition, it may be a method that reports the result obtained by measuring the delay dispersion of the downlink signal in the communication terminal to the base station, for example, without depending on the actual distance between the communication terminal and the base station. In this case, even if the communication terminal is far away from the base station, if the visibility from the base station is good and the reflected waves are less, the CP length can be set shorter, which can improve the frequency utilization efficiency.

[0262] Regarding the format of the uplink signal, the base station measures the delay dispersion, determines the CP length of the uplink signal based on the result, and indicates the CP length from the base station to the communication terminal. This can improve frequency utilization efficiency. Alternatively, when the uplink and downlink are at the same frequency, such as in time division duplex (TDD), the base station can measure the delay dispersion of the uplink signal from the communication terminal and set the CP length of the downlink signal corresponding to it.

[0263] In addition, for example, the CP length may be determined for each beam of a multi-element antenna in the same base station or the same cell, without depending on the actual distance between the communication terminal and the base station. In this case, for example, when the directivity of the beam in the elevation direction is controlled and the directivity of the beam is screened at a position close to the base station, the CP length is shortened. On the contrary, when the beam reaches a position far from the base station, the CP length is increased.

[0264] For example, when a plurality of element antennas are used and the beam becomes very narrow, the delay dispersion decreases. Therefore, by using the delay dispersion report value from the communication terminal, it is possible to determine and control whether the CP length can be shortened even if the communication terminal is far away from the base station.

[0265] Next, a method of setting the CP length will be described. In this embodiment, the following first to third methods are disclosed as methods of setting the CP length.

[0266] The first method is a method of detecting the CP length by the receiving side without notifying a message. Fig.16 and Fig.17 is a diagram showing an example of a resource block into which a training sequence is inserted. Fig.16 and Fig.17 The horizontal axis represents frequency f, and the vertical axis represents time t. Fig.16 and Fig.17 The case where a training sequence is inserted into a resource block of 8 subcarriers×11 OFDM symbols is shown.

[0267] Fig.16 In the example shown, all OFDM subcarriers at t1 and t12 at the beginning of each of the two resource blocks serve as training sequences. In this case, the receiving device can calculate the CP length when receiving the first symbol of the resource block. Thus, the CP length can be changed in units of resource blocks.

[0268] Fig.17 In the example shown, only the training sequences at t1 of the frequency f4 and t1 of the frequency f8 are transmitted discontinuously, so the receiving side detects the CP length based on the signal. This can increase the transmission data and improve the frequency utilization efficiency.

[0269] The second method is to set the CP length of the resource notifying the message containing the CP length control information to a fixed or relatively long CP length, and to set the CP length of the resource for transmitting and receiving data to a CP length that matches the CP length control information. The CP length control information includes information on the CP length of the data to be transmitted and the CP length used by the communication terminal.

[0270] The allocation of resources for notifying messages containing CP length control information can be set to resource blocks containing frequencies near the center of OFDM subcarriers that are transmitted periodically, for example, every 10 ms. Thus, even communication terminals that only use a narrow frequency band near the center of OFDM subcarriers can exchange control information using the same frequency.

[0271] In particular, when the CP length is set for each beam, the CP length of the common channel of each beam, such as a broadcast channel, can be set to a fixed or relatively long CP length, and the CP length control information can be notified. As a result, the communication terminal using the beam can know the CP length used for data transmission and reception by receiving the common channel. Therefore, the CP length can be set to match the setting conditions of the beam, such as making the directivity of the beam toward a position closer to the base station, so that the frequency utilization efficiency can be improved.

[0272] Fig.18 It is a diagram for explaining a modified example of the second method. Fig.18 The horizontal axis represents frequency f, and the vertical axis represents time t. Fig.18 As a variation of the second method, a case where the CP length is specified in advance based on the configuration of time resources used for communication is shown. Fig.18 In the example shown, there are 24 resource blocks in the frequency f direction, and the same configuration is repeatedly used in units of 10 resource blocks in the time t direction. Fig.18 In the example, Tcp is used to represent the repetition period set by the CP length.

[0273] For example, the CP length of resource block groups (RBG) 1 and 3 is 128Ts, and the CP length of resource block groups (RGB) 2 and 4 is 384Ts. These resource allocation information and the set repetition period are notified to the communication terminal via a broadcast channel.

[0274] When resources are allocated to communication terminals near the base station by the MAC scheduler, they are selected from resource block groups (RBGs) 1 and 3. For example, f2 and t2 are specified for use.

[0275] The assigned communication terminal can determine the CP length based on the broadcast information and the assigned resource position information from the scheduler. If the communication terminal moves significantly and the scheduler needs to increase the CP length in the next assignment, it will select from resource block groups (RBGs) 2 and 4.

[0276] As described above, the CP length can be set only by specifying resource configuration, without exchanging control information for CP length setting each time. Fig.18 In the description, time resources are used, but a method of specifying the CP length in frequency resources or resource block units is also effective.

[0277] Furthermore, in the above-described example, two CP lengths are used as an example for explanation, but three or more CP lengths are also effective.

[0278] The CP length setting repetition period described above is preferably an integer fraction of the repetition period of the broadcast information.

[0279] When carrier aggregation is performed, different settings can also be made according to the carrier components.

[0280] The third method is to use a wireless format with an increased CP length and change the CP length after the usage status and usage conditions are met.

[0281] For example, in the initial stage of communication, during the DRX active time, at the moment when DRX has just ended, the wireless format with an increased CP length is used, and after the communication terminal notifies that time synchronization with the base station has been fully achieved, the base station changes the CP length. Conversely, the base station increases the CP length according to the DRX start instruction.

[0282] In the present embodiment as described above, the base station device is configured to change the wireless format for the communication terminal device according to the change in the environment of the wireless communication between the base station device and the communication terminal device and the change information including the position of the communication terminal device. Thus, a more appropriate wireless format can be set for each communication terminal device. Therefore, a communication system that can realize data transmission at a higher speed and with a smaller delay can be obtained.

[0283] In addition, in the existing 3GPP messages, the CP length of the uplink can be changed through RRC Connection Reconfiguration, etc., but the CP length of the downlink cannot be changed. In contrast, in the present embodiment, even for downlink signals, the following can be achieved: (1) changing the CP length according to the distance from the base station to the communication terminal, and (2) changing the OFDM symbol length according to the moving speed of the communication terminal. Therefore, a good communication environment can be maintained in response to changes in communication conditions caused by higher frequencies and shorter symbol lengths in the 5G wireless access system.

[0284] Similar to the first embodiment, the procedure for changing the wireless format (CP length) in the second embodiment will be described below.

[0285] A method for a communication terminal to notify a base station of at least one of its own position, the distance to the base station, and a delay dispersion measurement value is described.

[0286] When initially connecting or starting communication with a base station at a mobile destination due to handover, the communication terminal sends a synchronization signal to the base station, such as the random access preamble in Chapter 10.1.5.1 and Chapter 10.1.5.2 of Non-Patent Document 1 (3GPP TS36.300).

[0287] When the base station receives the synchronization signal transmitted by the communication terminal, it transmits a signal notifying the reception of the synchronization signal as a random access response, and corrects the transmission timing of the communication terminal so that the communication terminal can transmit while the base station is on standby.

[0288] The communication terminal that receives the signal transmitted by the base station transmits an RRC (Radio Resource Control) connection request as control information for enabling communication dedicated to the communication terminal. The RRC connection request may include at least one of the position of the communication terminal, the distance to the base station, and the delay dispersion measurement value.

[0289] The base station that receives the RRC connection request takes into account the status of the base station's wireless resources for other communication terminals, such as whether there are idle resources, and then sends a wireless format change instruction corresponding to the moving speed, such as an OFDM subcarrier spacing change instruction. After sending the change instruction, the base station starts to transmit and receive using the new wireless format after receiving a response of approval of the change instruction from the communication terminal.

[0290] A communication terminal may be unable to change the wireless format in order to transmit the same signal while communicating with other base stations as in CoMP. Therefore, the communication terminal considers the communication status and returns a response of approval or denial of the change instruction to the base station.

[0291] In the above steps, the wireless format can be changed reliably, but the number of exchanges between the base station and the communication terminal increases. In order to avoid the above situation, once the base station sends a wireless format change instruction to the communication terminal, the base station can start to use the wireless format after the change instruction for transmission and reception. In this case, it is unclear whether the communication terminal can receive the change instruction from the base station, and there is also a case where even if it is received, it does not agree to the change depending on the communication status of the communication terminal.

[0292] Therefore, the following situation is effective: setting a timer, and returning to the original wireless format for transmission and reception when communication cannot be established after the wireless format is changed. Specifically, it is effective to set the timer to measure the following time: after the base station sends a wireless format change indication to the communication terminal, the change approval message (RRC) after the wireless format change is sent from the communication terminal to the base station using the new wireless format, until the base station can receive the change approval message.

[0293] In addition, as another example of the above example, the process is the same as the above example until the random access response is received, but the RRC connection request after receiving the random access response may include a change in the wireless format calculated based on at least one of the location of the communication terminal, the distance from the base station, and the delay discrete measurement value, such as a change in the CP length.

[0294] In the above random access example, a method of notifying at least one of the position of the communication terminal, the distance from the base station, and the delay dispersion measurement value by using the exchange with the communication terminal is shown, but it can also be as follows. For example, when a handover request (Handover Request) is sent from the mobile source base station to the mobile destination base station via the X2 interface, at least one of the position of the communication terminal, the distance from the base station, and the delay dispersion measurement value, or a wireless format determined thereby, such as CP length, can be notified.

[0295] The notification may be made by using a handover requirement (Handover Required) via the S1 interface, that is, via the MME, instead of via the X2 interface. In addition, the notification may be made by using a handover request (Handover Request) via the Xn interface in dual connectivity.

[0296] The base station at the destination of the mobile movement can notify the setting value of each physical channel when setting the wireless channel as a random access response to the signal for synchronization sent by the communication terminal to the base station at the destination of the mobile movement. Specifically, as the setting value of the physical configuration, the wireless format indicated by the handover request (Handover Request) or the handover requirement (Handover Required), such as the CP length, can be notified from the base station at the source of the mobile movement. At this time, the base station at the destination of the mobile movement considers the wireless resource status of the base station for other communication terminals, such as whether there are idle resources, and notifies the indicated wireless format if there are idle resources.

[0297] Next, an example of measurement configuration is shown. When a base station and a communication terminal communicate, a method is also effective in which the base station transmits a measurement configuration (RRC) and the communication terminal transmits a measurement report (RRC) according to the configuration.

[0298] The communication terminal reports at least one of the location of the device, the distance to the base station, and the delay dispersion measurement value using the measurement report. The base station receiving the above content takes into account the wireless resource status of the base station for other communication terminals, such as whether there are idle resources, and then sends a wireless format change instruction corresponding to the moving speed, such as reconfiguration.

[0299] After receiving the change indication, the communication terminal considers the communication status with other base stations, such as whether CoMP is performed, and sends a change indication approval response without communicating with other base stations or using the same wireless format, and starts to transmit and receive using the new wireless format. After receiving the change indication approval response, the base station starts to transmit and receive using the new wireless format.

[0300] After sending the change instruction, the base station starts to transmit and receive using the new wireless format after receiving a change instruction approval response from the communication terminal. After receiving the change instruction approval response, the communication terminal starts to transmit and receive using the new wireless format.

[0301] Next, an example of sending a request to change the wireless format from a communication terminal is shown. The communication terminal may also send a request to change the wireless format, such as the CP length, derived from at least one of the location of the device, the distance from the base station, and the delay dispersion measurement value separately from the random access and measurement configuration.

[0302] After receiving the change request, the base station considers the wireless resource status of the base station for other communication terminals, such as whether there are idle resources. If there are idle resources, the base station sends a change approval response and starts to use the new wireless format for transmission and reception. After receiving the change approval response, the communication terminal starts to use the new wireless format for transmission and reception.

[0303] In addition, the above shows an example of indicating the wireless format such as CP length based on RRC, but in order to switch at a higher speed, it is also effective to use MAC to send and receive the type of wireless format. In addition, it is also effective to use physical signaling to notify the type of wireless format accompanying the transmitted data.

[0304] The above description describes an example in which the wireless format, for example, the CP length, is set for each communication terminal. However, it is also effective to set the wireless format for each communication terminal group.

[0305] It is also effective to group the communication terminals into three types: large delay discreteness, medium delay discreteness, and small delay discreteness as described above. For example, the following method is also effective: three wireless formats are notified in the settings of each physical channel notified when the channel is established, and the communication terminal switches the wireless format to be used according to the moving speed of the device, and the base station decodes from the three wireless formats without purpose, and uses the format that CRC becomes OK.

[0306] Alternatively, the following method is also effective: three wireless formats are notified in the settings of each physical channel notified when the channel is established, and when the communication terminal switches the wireless format according to the moving speed of the device, the number of the wireless format used is attached to the data using physical signaling. In this case, it is effective to set the wireless format to be fixed by physical signaling.

[0307] Implementation method 3.

[0308] As a technology for interference control between adjacent cells using the same frequency, there is eICIC (Enhanced Inter-cell Interference Coordination) discussed in 3GPP. In order to apply this technology, it is necessary to match the time and frequency units for data control between cells. As the minimum unit of time, a 1ms subframe is defined in the LTE system. Here, the time for data control refers to the smallest unit of data transmission and reception, which is equivalent to the resource block (RB) of LTE of 3GPP.

[0309] When a time mismatch occurs between cells, the signal of the mismatched portion interferes with the signals of each cell, and communication performance such as data throughput deteriorates.

[0310] In 5G wireless systems, it is assumed that various communication terminals are connected to a base station. In this case, it is assumed that each communication terminal is set with a different wireless format. For example, the wireless format is a parameter related to the OFDM symbol, and the OFDM symbol length, the frequency interval of the OFDM subcarrier, and the CP length (Cyclic Prefix) can be cited. In the case of mixed wireless formats, it is believed that the time and frequency units of data control do not match, and interference control between cells cannot show good performance.

[0311] In this embodiment, in order to solve the above-mentioned problem, when wireless formats are mixed, the data symbol lengths defined by the wireless formats are made the same. Here, the data symbol length refers to the time obtained by adding the OFDM symbol length and the CP length. Fig.19 This is a diagram showing an example of the wireless format of cell #1 and cell #2. Fig.19 The horizontal axis represents time t. Fig. 20 This is a diagram showing an example of parameters of the wireless formats of cell #1 and cell #2. Fig.19 and Fig. 20 The situation after the data symbol length (TL) is added in cell #1 and cell #2 is shown.

[0312] For example, Fig. 20As shown, in the case where two wireless formats are mixed, in the first wireless format shown as No. 1, the OFDM symbol length SL is set to 4.18 microseconds (μs), the CP length (CPL) is set to 5.15μs, and the total data symbol length (TL) is set to 9.33μs. In the second wireless format shown as No. 2, the OFDM symbol length SL is set to 8.33μs, the CP length (CPL) is set to 1.00μs, and the total data symbol length (TL) is set to 9.33μs. In this way, interference control for each data symbol length (TL) can be achieved, and communication with strong resistance to inter-cell interference can be achieved. For example, Fig.19 As shown, wireless format No. 1 is used in cell # 2, and wireless format No. 2 is used in cell # 1.

[0313] In addition, there is also a method in which, in mixed wireless formats, the data symbol length is set to an integer multiple of the reference data symbol length. In this case, interference control is performed in a time unit that is a minimum common multiple of the data symbol length used by the mixed wireless formats, so that communication can be performed without deteriorating the interference removal performance.

[0314] Furthermore, by setting the data symbol length to an integer multiple of the reference data symbol length, the time unit of the least common multiple can be shortened compared to the case where the symbol length of each wireless format is freely determined, thereby having the effect of shortening the interference control unit time.

[0315] Fig.21 This is a diagram showing an example of the wireless format of cells #1 to #3. Fig. 22 This is a diagram showing an example of parameters of the wireless formats of cells #1 to #3. Fig.21 and Fig. 22 The case where the data symbol of each wireless format is set to an integral multiple of the reference data symbol length is shown.

[0316] Fig.21 In FIG. 1 , A represents the time of the minimum control unit for interference control between cell #1 and cell #2. B represents the time of the minimum control unit for interference control between cell #1 and cell #3. C represents the time of the minimum control unit for interference control between cell #2 and cell #3. Fig. 22 Ra represents the ratio of the data symbol length when the data symbol length L of cell #1 is taken as a reference (=1).

[0317] like Fig.21 and Fig. 22As shown, the data symbol length of the wireless format used by cell #2 is twice the data symbol length L of the wireless format used by cell #1, that is, 2L. In addition, the data symbol length of the wireless format used by cell #3 is three times the data symbol length L of the wireless format used by cell #1, that is, 3L.

[0318] As a method for determining the unit time for interference control when the data symbol lengths between the cells are different, there are a method for sharing the information of the data symbol length between the adjacent cells for interference control and a method for using a fixed value. In the case of sharing the data symbol length, the unit time for interference control can be set to the minimum time according to the state of the adjacent cells, so that efficient data transmission and reception scheduling can be performed, and as a result, the frequency utilization efficiency can be improved. In addition, in the case of using a fixed value, it is not necessary to use the control message between the adjacent cells to send the information of the data symbol length, so that the control can be simplified. As a method for determining a fixed value, for example, there is a method for statically determining it in advance using a standard.

[0319] The method of sharing the data symbol length between cells varies depending on the cell configuration. Three examples are given as examples of cell configurations for performing interference control between cells. Fig.23 This is a diagram showing a communication system in which cells of independent and different base stations are adjacent to each other. Fig.24 This is a diagram showing a communication system in which one base station centrally manages multiple cells. Fig.25 This is a diagram showing a communication system in which macro cells and small cells overlap.

[0320] right Fig.23 The following describes a communication system in which cells of different independent base stations are adjacent to each other. Fig.23 The communication system shown includes an MME / S-GW unit (hereinafter sometimes referred to as “MME unit”) 3201 , a base station (E-UTRAN NodeB: eNB) 3202 , and a mobile terminal (User Equipment: UE) 3203 which is a communication terminal device. Fig.23 In the illustrated example, the communication system includes a plurality of eNBs 3202, specifically, two eNBs 3202. The MME unit 3201 includes a mobility management entity (Mobility Management Entity: MME), or an S-GW (Serving Gateway), or an MME and an S-GW.

[0321] UE3203 can communicate with eNB3202 wirelessly, and use wireless communication to send and receive signals. eNB3202 is connected to MME unit 3201 through S1 interface, and control information is communicated between eNB3202 and MME unit 3202. One eNB3202 can be connected to multiple MME units 3201.

[0322] The eNBs 3202 are connected to each other via an X2 interface, and control information is communicated between the eNBs 3202. The eNBs 3202 form a cell 3204. Fig.23 In the example shown, cells 3204 of two independent and different base stations, namely eNB3202, are adjacent.

[0323] When interference control is performed in the communication system where cells of different independent base stations are adjacent to each other, the data symbol length is sent to each other's base stations using signaling set on the interface between base stations. The signaling set on the interface between base stations here includes the case where it is performed via the MME unit using the S1 interface and the case where it is performed directly using the X2 interface. There are the following three methods for coordination between cells.

[0324] In the first method, the timing of changing the data symbol length is set to an arbitrary timing in each base station. After the data symbol length is changed, the data symbol length is notified by signaling set on the interface between base stations. After the notification is completed, interference control is performed using the new time unit. In this structure, the data symbol length can be changed with the communication terminal at the fastest speed, so the data symbol length can be changed according to the wireless environment and the state of the communication terminal, and a high wireless quality can be maintained.

[0325] In the second method, when the data symbol length is notified to the adjacent base station in advance, the change timing of the data symbol length is also notified, and the unit time of interference control is changed in both base stations according to the change timing of the data symbol length. In this case, the interference control matches the change timing of the data symbol length, so it is possible to suppress the degradation of the interference removal performance immediately after the data symbol length is switched.

[0326] In the third method, a common data symbol length change possible timing is predetermined as a system or between adjacent base stations, and the change is performed according to the timing. When a data symbol length change notification is delivered to other cells, it is considered that the change starts from the data symbol length change possible timing thereafter. It is considered that the change starts from the first interference control time after the data symbol length change possible moment. In this case, it is sufficient to only notify the execution of the change of the data symbol length, so there is an effect of reducing the information size of the signaling between base stations.

[0327] right Fig.24The communication system shown in the figure is explained in which one base station centrally manages multiple cells. Fig.24 The communication system shown includes one centralized control base station (hereinafter sometimes referred to as “ICBS”) 3301 and a plurality of remote base stations (Remote Radio Equipment: RRE) 3302 as base stations.

[0328] The centralized control base station 3301 performs baseband signal processing and mobile control of multiple remote base stations 3302. The remote base station 3302 performs wireless control processing. The centralized control base station 3301 and the remote base station 3302 are connected, for example, by optical fiber. A baseband signal processing unit can be installed in the remote base station 3302. The mobile terminal 3203 communicates with the remote base station 3302. Each remote base station 3302 constitutes a cell 3303 with a small coverage area.

[0329] In this structure, the centralized control base station 3301 holds the data symbol information of all cells 3303, so the information of the data symbol length is always in a shared state. Therefore, even if the data symbol length changes, it can be reflected in the interference control at a high speed. In addition, the minimum time unit for interference control can be calculated in real time and reflected in the control. In addition, the change timing of the data symbol length of each cell can be performed with a pause of the minimum time of the previous interference control.

[0330] right Fig.25 The communication system shown in the figure is described in which a macro cell and a small cell overlap. Fig.25 The communication system shown includes: an MME unit 3201 , a UE 3203 , a macro cell base station, namely a macro cell eNB (Macro eNB) 3401 , and a small cell base station, namely a small cell eNB (Small eNB) 3402 . Fig.25 In the example shown, the communication system includes multiple small cell eNBs 3402 , specifically, 2 small cell eNBs 3402 .

[0331] The macro eNB 3401 forms a macro cell 3403 with a relatively wide coverage area. The small eNB 3402 forms a small cell 3404 with a relatively small coverage area. Fig.25 The communication system shown has a structure in which a macro cell 3403 which is a cell of a macro cell eNB 3401 and a small cell 3404 which is a cell of a small cell eNB 3402 overlap (overlay).

[0332] The macro cell eNB3401 and the small cell eNB3402 sometimes use different carrier frequencies and sometimes use the same carrier frequency. Sometimes control information is communicated between the macro cell eNB3401 and the UE3203, and sometimes user data is communicated between the small cell eNB3402 and the UE3203. The interference control in this structure is mainly performed between adjacent small cell eNB3402.

[0333] When interference control is performed on UE3203, information sharing of data symbol lengths between small cell eNB3402 may be performed via the X2 interface between the small cell eNB3402, or may be performed via the macro cell eNB3401 using the Xn interface.

[0334] The change of the data symbol length can be changed dynamically according to the status of the communication terminal. For the timing of changing the data symbol length, the minimum control time when performing interference control between adjacent cells is calculated before and after the change, and the timing of changing the data symbol length is set to the timing that becomes the least common multiple of them. The minimum control time as the object can be calculated for all adjacent cells or for the cell performing interference control.

[0335] Fig.26 This is a diagram for explaining the timing of changing the data symbol length. This is an example of changing the data symbol length of cell #2 from the original setting: cell #2(1) to the new setting: #2(2). This is an example in which the data symbol length after adding the CP length (CPL) and the OFDM symbol length (SL) is L for cell #1, 2L for cell #2(1), and 3L for cell #2(2).

[0336] Fig.26 In FIG. 1 , A represents the minimum control time when interference control is performed between cell #1 and cell #2 (1), which is equivalent to 2L. B represents the minimum control time when interference control is performed between cell #1 and cell #2 (2), which is equivalent to 3L. C is the time that becomes the least common multiple of A and B, which is equivalent to 6L. When the data symbol is changed, the data symbol length is changed at the time period of C, such as the timing of arrow D, so that interference control between cells can be performed uninterruptedly.

[0337] Furthermore, for example, the data symbol length may be determined for each beam of a multi-element antenna. The present invention is also applicable when interference control is performed between beams in the same cell and when interference control is performed between a beam of the own cell and a beam of another cell.

[0338] An example of a method for generating information that can identify the timing of the data codeword length between base stations is shown. Each base station obtains the GPS time and generates a subframe timing synchronized with the GPS. The subframe counter of each base station is preset with the transmission period of the broadcast information. In this way, a subframe counter synchronized with the GPS is generated in all base stations, and synchronization can be achieved between base stations. The change timing of the data codeword length to be notified is set to a value obtained by adding the processing delay and margin to the current subframe count value. In this way, the change timing of the data codeword length can be matched between base stations.

[0339] exist Fig.24 In the case of the structure shown, the GPS can be located in the centralized control base station 3301 or in each remote base station 3302. Fig.25 In the case of the structure shown, it can be located in the macro cell eNB3401 or the small cell eNB3402.

[0340] The method of synchronizing with GPS is described above as a method of generating a subframe counter for synchronization between base stations. However, instead of using GPS, time may be synchronized using an NTP (Network Time Protocol) server, a communication terminal, or IEEE1588.

[0341] There are the following three methods for changing the data symbol length using a communication terminal.

[0342] In the first method, the base station in communication notifies the communication terminal of the timing of changing the data symbol length, such as the subframe number, and the base station and the communication terminal change the data symbol length together from the notified timing. In this case, any change timing can be specified, and information can be sent and received with each set communication terminal, so the change information of the data symbol length can be transmitted at a high speed, and interference control can be performed quickly according to changes in the wireless environment.

[0343] As a method of notifying information between a base station and a communication terminal, there are a method of adding information that can identify the timing of changing the data symbol length to an RRC message, and a method of adding information that can identify the timing of changing the data symbol length to L1 / L2 control information such as PDCCH. In addition, there is also a method of adding information that can identify the timing of changing the data symbol length to broadcast information.

[0344] In the above example, the base station notifies the communication terminal of the change timing, but sometimes the communication terminal notifies the base station in reverse. For example, there is a method of adding information that can identify the change timing of the data codeword length to L1 / L2 control information such as PUCCH.

[0345] In the second method, a common data symbol length changeable timing is predetermined between the system or the base station and the communication terminal, and the change is performed according to the timing. When a notification of a change in the data symbol length is sent from the base station or the communication terminal, it is assumed that the change will start from the subsequent data symbol length changeable timing. In this case, only the execution of the change in the data symbol length needs to be notified, so there is an effect of reducing the information size of the signaling between the base station and the communication terminal.

[0346] In the third method, the data symbol length is changed without the base station notifying the communication terminal of the change timing of the data symbol length. The communication terminal needs to detect the change of the data symbol length without purpose. As this method, there is a method of calculating the data symbol length by detecting the corresponding wireless format based on the insertion position of the training signal or the period of the training signal. In addition, there is also a method of adding the changed information to the L1 / L2 control information of the PDCCH after the data symbol length is changed in the base station, and a method of notifying the base station of the data symbol length in use by using broadcast information. In the third method, there is no need to strictly match the change timing of the data symbol length between the base station and the communication terminal, so the processing can be simplified.

[0347] Here, the communication terminal is UE3203, and the base station can apply the structure of any one of eNB3202, RRE3302, and small cell eNB3402. In addition, the setting information of the data codeword length can use the interface for changing the timing notification. The setting information and the change timing of the interface used can be the same or different. For example, the structure is as follows: the setting information uses L1 / L2 control information such as PDCCH, and the change timing uses broadcast information. In addition, the timing of notifying the setting information and the change timing can be simultaneous or different. In different cases, it is necessary to notify the change timing before notifying the setting information.

[0348] The data symbol lengths of the uplink and downlink do not need to be the same. Therefore, the change in the CP length may be a change in the uplink data symbol length only, or a change in the downlink data symbol length only.

[0349] The data symbol length in the cell is set to be variable in subframe units, TTI units, or each RB, so that control matching the modulation and demodulation processing unit can be achieved, and the modulation and demodulation processing can be simplified. In addition, the data symbol length of the interference control time is the minimum unit, and can be set to an integer fraction of a subframe (e.g., 1 / 2) or an integer fraction of a TTI time (e.g., 1 / 4). As a result, interference control can be performed in accordance with the control time of the modulation and demodulation processing, which has the effect of simplifying the MAC scheduling processing, etc.

[0350] Implementation method 4.

[0351] In the wireless system assumed by the 5G system, a wireless format in which at least one of the OFDM symbol length and the CP length is different is considered to be mixed. In addition, the case where the OFDM symbol length and the CP length change dynamically is also considered. In the LTE system method, if the cell-specific reference signal (CRS) is considered in the time direction, 2 symbols are usually inserted into 7 OFDM symbols. The 0th symbol (starting: the 1st) and the 4th symbol (the 5th).

[0352] When there are mixed wireless formats, it is considered to define the position where the cell-specific reference signal (CRS) is inserted as the optimal position for each wireless format. For example, in order to simplify the modulation and demodulation process, the insertion ratio of the CRS for data may be fixed. Fig. 27 This is a diagram showing an example of the insertion ratio of the cell-specific reference signal (CRS). Fig. 27 The horizontal axis represents time t. T1 and T2 are the code elements for inserting data. Fig. 27 As shown, CRS is inserted at a ratio of 1 symbol for every 4 symbols. In this case, the CRS insertion interval becomes the sum of the CRS length and the data length, which is CRS length + T1 and CRS length + T2.

[0353] Fig.28 This is a diagram showing an example of the insertion interval of the cell-specific reference signal (CRS). Fig.28 The horizontal axis represents time t. T3 and T4 are code elements for inserting data. T5 shows the insertion interval of CRS. For the above situation, even when wireless formats are mixed, the insertion interval T5 of the cell-specific reference signal (CRS) in the time direction is made the same in multiple wireless formats. As a result, the control timing of CRS generation in the base station becomes the same, which can simplify the device and simplify the processing even when a communication terminal communicates simultaneously using multiple wireless formats.

[0354] In addition, by inserting CRS into all OFDM symbols at a fixed ratio, the CRS insertion interval is determined according to the characteristics of the communication terminals accommodated in the cell, thereby reducing the occupancy rate of CRS in all OFDM symbols and improving the frequency utilization efficiency. The characteristics of the communication terminal refer to the influence of, for example, the moving speed of the mobile terminal and the installation location of the base station.

[0355] If it is the moving speed, for cells with slower moving speed and less influence of Doppler frequency shift, the CRS insertion interval is increased and the CRS occupancy rate is reduced. On the contrary, for cells with faster moving speed and greater influence of Doppler frequency shift, there is also a method to improve the reception performance by reducing the CRS insertion interval. When the moving speed becomes faster, there is a situation where CRS is inserted into all OFDM symbols of a certain frequency to the maximum extent.

[0356] In addition, when the mobile speed is very slow, it is effective to increase not only the CRS insertion interval in the time direction but also the CRS insertion interval in the frequency direction. When the mobile speed is very slow, not only the influence of Doppler frequency shift is small, but also the change of wireless transmission environment is small, so even if the CRS insertion rate is reduced, the degradation of reception performance is also reduced.

[0357] Therefore, even if the CRS insertion interval in the frequency direction is increased, the reception performance will not deteriorate, and the frequency utilization efficiency can be improved. When the CRS insertion interval in the frequency direction is increased, there is a possibility that the reception performance will deteriorate at a specific frequency when frequency selective phasing occurs. In this case, the degradation of the reception performance can be reduced by changing the CRS allocation frequency according to the CRS insertion time or performing frequency hopping.

[0358] If the base station is set up in a place like a city with many buildings and people and low visibility, the wireless transmission environment will change greatly due to the influence of frequency selective phasing, so there is also a method to reduce the CRS insertion interval and improve the reception performance.

[0359] Fig.29 This is a diagram showing an example of the CRS insertion interval and insertion ratio when the OFDM symbol length is different. Fig.29 The horizontal axis represents time t, and the vertical axis represents frequency f. It shows a state where wireless formats REF#1, REF#2, and REF#3 with different OFDM symbol lengths SL and OFDM subcarrier spacings SCI coexist. In the case of different OFDM symbol lengths, if the insertion interval of CRS in the time direction is set to be the same, the synthetic power of CRS in the case of the wireless format with a shorter OFDM symbol length becomes smaller, and the required reception performance such as SNR (Signal Noise Ratio) may not be ensured in the reception of CRS at the communication terminal. Therefore, there is also a method of increasing the insertion ratio of CRS in the frequency direction (increasing the number of CRS insertion subcarriers) and increasing the transmission power of the CRS insertion symbol relative to other OFDM symbols.

[0360] The insertion ratio of CRS in the frequency direction can be determined for each beam of a multi-element antenna. When a beam is formed by a multi-element antenna, the transmission power and the radiation angle of the beam can be changed according to the number of elements forming the beam. Therefore, there is also a method as follows: for example, for a beam with a large number of elements, the insertion ratio of CRS in the frequency direction is reduced, and the resources used for data transmission are increased while satisfying the required SNR, thereby improving the frequency utilization efficiency.

[0361] In addition, as with the above-mentioned CRS, UE-specific reference signals, namely data demodulation reference signals (DM-RSs), can be set to be the same in different wireless formats, thereby simplifying the control of base stations and communication terminals. DM-RSs can be set for each communication terminal, so the insertion interval of DM-RSs can be determined for each communication terminal based on the reception performance, reception quality information, antenna structure, amount of data sent and received, and allowable processing delay of the communication terminal.

[0362] As a method of notifying the communication terminal of the insertion interval and insertion ratio of CRS, there is a method of sending the insertion interval and insertion ratio using broadcast information. By inserting it into the broadcast information, all communication terminals can be notified at the same time, and by changing SI (System Information), it can also respond when the CRS insertion interval and insertion ratio settings are changed.

[0363] The insertion interval and insertion ratio of DM-RSs can be changed dynamically for each communication terminal according to reception quality, etc. In a communication terminal, there are the following two methods for changing the insertion interval and insertion ratio of DM-RSs.

[0364] In the first method, the base station in communication notifies the communication terminal of the setting change content and timing (e.g., subframe number) of DM-RSs, and the base station and the communication terminal change the setting of DM-RSs from the notified timing. In this case, any change timing can be specified, and information can be sent and received with each communication terminal set, so the change information of the data code length can be transmitted at high speed, and rapid control can be performed according to changes in the wireless environment, etc.

[0365] As a method for notifying information between a base station and a communication terminal, there is a method of attaching information that can identify the changed content and change timing of the DM-RSs configuration to an RRC message, and a method of attaching information that can identify the DM-RSs configuration to L1 / L2 control information such as PDCCH. In addition, there is also a method of attaching information that can identify the changed content and change timing of the DM-RSs configuration to broadcast information.

[0366] The above is an example of notifying the communication terminal of the changed content and change timing of the DM-RSs setting from the base station, but sometimes the communication terminal also notifies the base station in the opposite direction. For example, there is a method of adding information that can identify the changed content and change timing of the DM-RSs setting to L1 / L2 control information such as PUCCH.

[0367] In the second method, a common change timing of the data symbol length is predetermined as a system or between a base station and a communication terminal, and the change is performed according to the timing. When a change notification of the setting of DM-RSs is sent from a base station or a communication terminal, it is determined that the change starts from the change timing of the setting of DM-RSs thereafter. In this case, it is sufficient to notify the execution of the change of the setting of DM-RSs, so there is an effect of reducing the information size of the signaling between the base station and the communication terminal.

[0368] Implementation method 5.

[0369] In the wireless system assumed by the 5G system, various communication terminals are connected. For example, it is assumed that the equipment used in FA (Factory Automation) is also connected to the same system as a communication terminal. FA equipment attaches importance to real-time performance, and sometimes it is impossible to use data from the past as valid data.

[0370] The biggest cause of processing delay in the wireless system is the retransmission of HARQ or RCL. In the case of the FA device described above, it is considered to treat the retransmitted data such as HARQ as invalid data. However, in the LTE system mode, HARQ is a necessary function, and wireless resources for HARQ must be ensured regardless of the type of communication terminal connected. Therefore, even for communication terminals that do not require HARQ retransmission, resources for replying HARQ ACK / NACK and instructions for scheduling information accompanying retransmission are generated, resulting in wasteful use of wireless resources.

[0371] In the future, 5G systems will require the connection of 100 times more communication terminals than the current wireless systems using MMC (Massive Machine Connection), etc. Therefore, it is known that the occupancy rate of wireless resources for retransmission control such as HARQ will also increase.

[0372] Fig.30 This is a diagram showing an example of a control operation in a conventional communication system. Fig.30 The horizontal axis of represents time t. The base station BS is connected to the device, and the device includes a device control unit UE_C and a communication control unit UE having the function of a UE. This is an example of changing the control action based on event information from the base station BS.

[0373] An event occurs in step ST3901, and the base station BS sends the event information as Data (1) to the device in step ST3903. The communication control unit UE of the device demodulates the data, but the demodulation fails, and Data (1) cannot be reflected in step ST3909. In step ST3904, a HARQ NACK is returned to the base station BS.

[0374] The base station BS retransmits Data (1) in step ST3905. Since the communication control unit UE of the device has successfully completed the demodulation of the data, an ACK is returned in step ST3906.

[0375] However, from the control point of view of the device controller UE_C, the reception of Data (1) is late and is unusable data, so it is discarded in step ST3910. At this time, the device controller UE_C operates independently in step ST3912.

[0376] In step ST3902, a new event occurs, and the base station BS sends Data (2) in step ST3907. The communication control unit UE of the device correctly receives Data (2), so it is reflected in the device control unit UE_C in step ST3911, and the device control unit UE_C performs a control action based on the information of Data (2) in step ST3913. In addition, ACK is replied in step ST3908. Fig.30 In the example, steps ST3904, ST3905, and ST3906 are not required.

[0377] In order to solve the above problems, a mode in which HARQ control is not performed is added to each communication terminal or each radio bearer. In the same system, a mode in which HARQ is performed and a mode in which HARQ is not performed can be mixed, so that by reducing unnecessary HARQ processing, the wireless resources accompanying unnecessary HARQ can be used for data communication, etc., which can improve the frequency utilization efficiency. In addition, the processing of communication terminals that do not require HARQ processing is reduced, which also helps save power consumption.

[0378] The units for selecting whether to perform HARQ processing include (1) each communication terminal, (2) each radio bearer, (3) at a certain fixed time interval, (4) each transmitted data (data packet), (5) each LCG (Logical Channel Group), (6) each CC in the case of a carrier aggregation CA cell, (7) each MeNB in ​​a dual-connection DC configuration, each SeNB, (8) each type of communication terminal, (9) each QoS, (10) switching whether to perform HARQ at a predetermined time, etc. As a method for sharing the setting of whether to perform HARQ processing between the base station and the communication terminal, there are L1 / L2 control information, MAC control information, and RRC control information.

[0379] As the selection method for each communication terminal in (1) above, for example, there is a method in which the presence or absence of HARQ is determined based on the processing capability and usage environment of the communication terminal, and the communication terminal notifies the base station using UE capability or the like.

[0380] As a method of selecting each radio bearer in (2) above, for example, there is a method in which the bearers for video and audio emphasize real-time performance and are set to be without HARQ, and the bearers for data packet transmission emphasize reliability and are set to be with HARQ.

[0381] As the selection method for each fixed time period in (3) above, there is, for example, a method in which the control signal transmission time is set to have HARQ, and the user data signal transmission time is set to have no HARQ.

[0382] As a selection method for each transmission data (data packet) of the above (4), for example, there is the following method: monitor the communication quality, and when the communication condition is good (for example, the SNR is high), set it to be without HARQ to improve the frequency utilization efficiency; on the contrary, when the communication condition is poor, set it to be with HARQ and use the HARQ action to improve the communication quality.

[0383] As a selection method for each LCG in (5) above, for example, there is a method as follows: for a higher priority LCG, HARQ is set to be enabled to ensure communication quality, and for a lower priority LCG, HARQ is set to be disabled to reduce the occupied frequency band of wireless resources.

[0384] As a method for selecting each CC in the case of the CA cell in (6) above, for example, there is a method of setting HARQ-free for CCs with good communication quality and setting HARQ-free for CCs to which communication terminals requiring low delay such as FA devices are allocated to achieve low delay.

[0385] As a selection method for each MeNB and each SeNB in ​​the DC configuration of (7) above, there is the following method: MeNB processes control information, so HARQ is set to ensure quality, and SeNB is set to no HARQ in order to achieve low delay of user data.

[0386] As a method for selecting the type of each communication terminal in the above (8), for example, there is the following method: the communication environment of a non-mobile terminal does not change, and since the communication environment does not change, it is set to be without HARQ; the communication environment of a mobile terminal that realizes low latency will change, and therefore it is set to have HARQ, thereby being configured to maintain quality in the event of a drastic change in the communication environment.

[0387] As a method for selecting each QoS in (9) above, for example, there is a method of providing HARQ when high quality needs to be ensured, and providing HARQ without HARQ when low quality is sufficient, so as to improve frequency utilization efficiency.

[0388] As a method of switching the presence or absence of HARQ at a predetermined timing in (10) above, for example, there is a method in which HARQ is set to be present for control information until the initial establishment of communication, and HARQ is set to be absent for subsequent user data communication.

[0389] As L1 / L2 control information, there is a physical downlink control channel (PDCCH) in the LTE system. By adding information indicating whether HARQ is performed to the L1 / L2 control information, it is possible to select whether HARQ is performed for each transmission data. For downlink transmission, whether HARQ is performed can be added to the allocation information of the downlink shared channel. In addition, for uplink transmission, whether HARQ is performed can be added to the information of the uplink scheduling permission. As a feature of notification under PDCCH, it has the advantage of being able to respond instantly and only applying changes to the corresponding PDSCH.

[0390] In this case, any of the following changes can be made: (1) for each communication terminal, (2) for each radio bearer, (3) at a fixed time interval, (4) for each transmitted data (data packet), (5) for each LCG (Logical Channel Group), (6) for each CC in the case of a cell for carrier aggregation CA, (7) for each MeNB in ​​a dual-connection DC configuration, each SeNB, (8) for each type of communication terminal, (9) for each QoS, and (10) switching the presence or absence of HARQ at a predetermined timing (for example, the control information when performing the initial connection is set to have HARQ, and then set to have no HARQ). In this case, the base station notifies the communication terminal of the setting.

[0391] As MAC control information, HARQ setting information is added to information such as MAC-CE (Medium Access Control-Control Element) that performs initial setting and resetting of Layer 2 level, and whether or not HARQ is performed is changed at the set timing. In the LTE system, this corresponds to RRC control information such as RRC Connection Reconfiguration.

[0392] In this case, changes can be made (1) for each communication terminal, (2) for each radio bearer, (3) at fixed intervals, (5) for each LCG (Logical Channel Group), (6) for each CC in the case of a carrier aggregation CA cell, (7) for each MeNB in ​​a dual-connection DC configuration, each SeNB, (8) for each type of communication terminal, (9) for each QoS, and (10) at a predetermined timing to switch whether or not to have HARQ (for example, control information when performing the initial connection is set to have HARQ, and then set to have no HARQ). In this case, the base station notifies the communication terminal of the setting.

[0393] As RRC control information, the UE capability information is added to set whether or not to perform HARQ when the communication terminal sets up a wireless connection. In this case, the setting can be made for (1) each communication terminal or (8) each type of communication terminal. In this case, the communication terminal notifies the base station of the setting.

[0394] In the LTE system, the QoS (Quality of Service) of each radio bearer is defined by QCIs (Quality Class Identifiers). Whether or not HARQ is executed is added to the QCIs table, and the configuration can be made for each radio bearer (2).

[0395] The above describes the method for setting whether or not HARQ is present. Once HARQ is set, it is valid to continue the set state before entering the next trigger. In the LTE system mode, various L1 / L2 control information is set each time PDSCH is sent. In the case of continuous setting, it is not necessary to perform the setting each time PDSCH is sent, which can reduce control information, reduce control information overhead, and improve frequency utilization efficiency.

[0396] As a trigger for stopping the continuous state of the setting, there are the following methods. (1) There is a HARQ setting continuation timer, which continues until the timer expires. The timer value is set in advance. It can be fixedly determined by the standard or the setting file of each base station. (2) It continues until there is a request for setting change from the communication terminal, base station or the upper device of the base station. For example, in the case of deterioration of reception performance, the state without HARQ is stopped and a change request to change to HARQ is output. As a detection method for deterioration of reception performance, for example, there is a method of calculating the error rate based on the CRC check of data and a method of measuring the SNR (Signal Noise Ratio) based on the training signal.

[0397] In addition, it is also effective to predetermine the default value of whether or not HARQ is present. When communication has already started, if there is no setting for whether or not HARQ is present, for example, HARQ is set to be present. By presetting the default value, the overhead of control information can be further reduced. The default value can be fixedly determined by the standard or the setting file of each base station. In addition, the default value of whether or not HARQ is present can be made known by broadcast information.

[0398] The above-mentioned presence or absence of HARQ execution can also help save power consumption of communication terminals such as sensor devices. For example, by executing HARQ only for necessary information such as control information, and not executing HARQ for other information, it is possible to eliminate the situation where unnecessary HARQ-ACK / NACK is sent. As a method of reducing HARQ processing, there is also a method of only sending HARQ-ACK when data demodulation is completed normally, and not sending HARQ-NACK when data demodulation is erroneous. In this case, retransmission is automatically repeated until HARQ-ACK is received. In this case, as a method of stopping retransmission, there is a method of stopping using an RRC message, etc., and a method of stopping retransmission when the maximum number of retransmissions is reached.

[0399] Implementation method 6.

[0400] In the 5G system, the formalization of MTC (Machine Type Communication) is being considered. MTC also contains communication terminals with very small requirements such as processing latency of more than 30 seconds. In the LTE system specification, the TTI (Transmission Time Interval) interval is unified in 1 subframe (1ms) for all communication terminals, and even in the case of MTC, it is necessary to operate according to 1 subframe.

[0401] The TTI of implementation mode 6 is the unit time for determining the ACK / NACK of HARQ. In other words, it is the unit time for sending data after channel coding. CRC is added to the data of 1TTI and HARQ is replied. Therefore, CRC is not added to the data of 2TTI and HARQ ACK / NACK is not performed. Therefore, even MTC with looser processing delay regulations needs to act in units of 1 subframe, and the retransmission action performed by HARQ also needs to be processed in the same cycle as other communication terminals.

[0402] In the uplink of the LTE system specification, the HARQ retransmission cycle is 8 subframes. Here, TTI in the LTE system specification is the time for checking CRC (Cyclic Redundancy Check) when performing HARQ, and the HARQ retransmission process is performed in data units allocated to 1 TTI.

[0403] Therefore, even MTC communication terminals require instantaneous high-speed processing, and high-performance devices that can handle it are required. In addition, the transmission timing of HARQ retransmission data is determined and prioritized, so even data with a lower priority like MTC sometimes has a higher priority than other data instantaneously, hindering the transmission of other data with a higher priority.

[0404] In order to overcome the above-mentioned problems, a structure is adopted in which the TTI period can be set for each mobile terminal or each radio bearer, and these can exist in a mixed manner. Fig.31 is a diagram showing an example of the period of TTI of mobile terminal UE#1 and mobile terminal UE#2. The OFDM symbol length is set to SL. For example, Fig.31 As shown, the following system is adopted: in order to make a certain mobile terminal UE#1 operate with low processing delay, 1TTI can be operated with T11, for example, 0.1ms, and for a mobile terminal UE#2 such as MTC, 1TTI is set to T12, for example, 1000ms. In addition, by making all TTI lengths mixed to be integer multiples of the reference TTI length, it is possible to simplify the scheduling control of RB resource allocation when communication terminals with different TTI lengths are mixed.

[0405] As a result, the HARQ cycle of mobile terminals such as MTC can also be increased, which can eliminate the instantaneous load of the mobile terminal and the instantaneous shortage of wireless resources.

[0406] Fig.32 This is a diagram showing an example of a HARQ cycle when different TTIs exist in a mixed manner. Fig.32 The horizontal axis of represents time t. A shorter TTI is set for the mobile terminal UE#1, and a longer TTI is set for the mobile terminal UE#2.

[0407] In step ST4101, the base station BS transmits data to the mobile terminal UE#1. Step ST4102 shows the TTI length (hereinafter sometimes referred to as "TTIL") of the mobile terminal UE#1, which is the data length for performing HARQ processing. The mobile terminal UE#1 demodulates the data during step ST4102, and replies HARQ ACK / NACK to the base station BS in step ST4103. The base station BS observes the result of step ST4103, and if it is NACK, it retransmits the next data in step ST4101.

[0408] Similar to the example of mobile terminal UE#1, for mobile terminal UE#2, data is sent in step ST4104, data is received in step ST4105, and then the demodulation result is returned to the base station BS in step ST4106.

[0409] according to Fig.32 The mobile terminal shown can change the HARQ cycle, and does not need to retransmit the data with lower priority at the same time interval as the data with higher priority, thereby reducing the obstruction of data transmission to the mobile terminal with higher priority such as the mobile terminal UE#1. In addition, the data transmitted in 1TTI is configured so that RB resources can be arbitrarily allocated and the data amount can be controlled, so that in the case of a plurality of mobile terminals mixed, more flexible scheduling can be achieved, and priority control of each mobile terminal can be easily achieved.

[0410] As a method of mixing TTI cycles, there is a method of determining a reference TTI (minimum TTI) and setting a TTI that is an integer multiple of the TTI. In this case, the base station device operates based on the reference TTI, which can simplify scheduling.

[0411] Data allocation to OFDM symbols within a TTI does not need to be continuous like downlink signals in the LTE system, and by reducing the amount of processing per unit time, allocation that can be processed by low-speed devices used in MTC and the like can be achieved. Fig.33 This is a diagram showing an example of data allocation to OFDM symbols within a TTI. Fig.33 An example of reducing the amount of processing per unit time is shown. Specifically, it is an example of transmitting 4 symbols of data every 40 ms.

[0412] Fig.33 (a) shows an example when the TTI length T21 is 1 ms, Fig.33(b) shows an example when the TTI length T23 is 40ms. When the TTI length T21 is 1ms, the amount of data processed per subframe is a maximum of 4 symbols. In addition, when HARQ retransmission is performed, the load is concentrated in the first half of 40ms. For example, when retransmission data (RTD) is received after T22, for example, 7ms, 8 symbols are processed within 9ms. On the other hand, when the TTI length T23 is set to 40ms, the amount of data processed per subframe is a maximum of 1 symbol, and when HARQ retransmission occurs, retransmission is performed at a timing of 40ms. For example, Fig.33 (b) is an example of performing retransmission T24, for example, 7ms after TTI.

[0413] Fig.33 In (b), in order to further realize low power consumption of the mobile terminal, it is also effective to start the mobile terminal and perform processing only for the codewords with data, such as DRX (Discontinuous Reception) in the LTE mode. In this case, there are methods of performing fixed scheduling, methods of notifying the allocation of data within 1TTI in advance using PDCCH (scheduling information), and methods of setting the RB allocation in the time direction to a fixed period so that PDCCH (scheduling information) can be decoded without being decoded.

[0414] The TTI setting units are (1) each mobile terminal, (2) each radio bearer, (3) every fixed time, and (4) each transmitted data (data packet). As a method for sharing TTI settings among base stations and mobile terminals, there are L1 / L2 control information, MAC control information, and RRC control information.

[0415] As L1 / L2 control information, the LTE system has a physical downlink control channel (PDCCH). By adding information indicating the TTI setting to the L1 / L2 control information, the TTI setting for each transmitted data can be selected. For downlink transmission, the TTI setting can be added to the allocation information of the downlink shared channel, and for uplink transmission, the TTI setting can be added to the uplink scheduling permission information. In this case, any of the changes can be made (1) for each mobile terminal, (2) for each radio bearer, (3) at a fixed time interval, and (4) for each transmitted data (data packet).

[0416] As MAC control information, TTI settings are added to information such as initial settings or reconfiguration of Layer 2, and TTI settings are changed at the set timing. In the LTE system mode, this is equivalent to RRC connection reconfiguration. In this case, changes can be made (1) for each mobile terminal, (2) for each radio bearer, and (3) at fixed intervals.

[0417] As RRC control information, the UE capability information is added to set whether or not to perform HARQ when the mobile terminal sets up a wireless connection. In this case, it is possible to set it for each mobile terminal (1).

[0418] In the LTE system, the QoS (Quality of Service) of each radio bearer is defined by QCIs (Quality Class Identifiers). The TTI setting is added to the QCIs table, and the setting can be performed for each radio bearer (2).

[0419] In a system that uses a multi-element antenna to form a beam, it is also effective to change the TTI setting for each beam. For example, when communicating with a mobile terminal that moves at high speed or when using a thinner beam, since the mobile terminal moves outside the illumination range of the beam in a short time, it is necessary to shorten the TTI period, feed back the intensity of the received power of the beam in the mobile terminal, and the channel information of the wireless transmission interval such as the precoding of MIMO (Multiple Input and Multiple Output) to the mobile terminal, and control the direction of the beam. On the contrary, when a coarser beam is used, the mobile terminal moves outside the illumination range of the beam less frequently even if the TTI period is increased compared to the case of using a thinner beam. Generally speaking, when the number of antenna elements is large, the beam width becomes thinner, and when the number of elements is small, the beam width becomes thicker. Therefore, it is also effective to determine the TTI length based on the number of antenna elements.

[0420] Methods of notifying a mobile terminal of the TTI length include a method of notifying using L1 / L2 control information such as PDCCH, a method of notifying using scheduling information of MAC, and a method of notifying using an RRC message.

[0421] Implementation method 7.

[0422] In the LTE system scheme, the downlink synchronization signal is allocated only to the 72 subcarriers (1.08 MHz band portion) at the center of the transmission frequency. Fig.34 This is a diagram showing an example of the allocation of synchronization signals (SS) and data. The frequency band BW used in the 5G system is widened (for example, 500MHz), so when only subcarriers with center frequency W1 are allocated, all mobile terminals need to be synchronized at the center frequency and then move to the frequency band W2 used for data transmission and reception.

[0423] In the case of the above-mentioned system, even if the device only uses a narrow frequency band, it is necessary to support dual frequency bands, and thus use a wide frequency band RF device or a circuit that switches the frequency between the dual frequencies, which leads to increased costs.

[0424] In the case of multiple mobile terminals with one frequency band corresponding only to narrow frequencies, all low-speed communication devices need to be allocated around the center frequency. When a large number of mobile terminals are connected as in MMC (Massive Machine Connection), there is a possibility of resource shortage.

[0425] As a solution to the above, consider CA (Carrier Aggregation) of the LTE-A system mode. In the CA mode, a maximum of 5 CCs (Component Carriers) with a frequency band of 20MHz are configured to achieve a wideband of 100MHz or the like. In this case, the center frequency can be allocated every 20MHz, so the synchronization signal (SS) can be configured every 20MHz. However, a mobile terminal capable of high-speed transmission needs to perform processing such as FFT every 20MHz, which makes the processing complicated. In the 5G system, a frequency band exceeding 500MHz is used, so in order to simplify the processing, it is considered to make the processing unit of FFT and the like larger. In this case, the above-mentioned problems such as insufficient resources corresponding to the MMC will occur.

[0426] In order to solve the above problems, the synchronization signal (SS) is not only configured at the center frequency, but also configured at a fixed frequency interval (for example, 20MHz interval) in the entire frequency band or the frequency band used by mobile terminals corresponding to narrow frequency bands such as sensors. As a result, the mobile terminal can synchronize with the synchronization signal (SS) near the frequency used for data communication without corresponding to dual frequency bands. In addition, even in systems such as MMC that are connected to a large number of mobile terminals, resources can be freely allocated.

[0427] Fig.35 This is a diagram showing an example of the arrangement of synchronization signals (SS) in a frequency band. Fig.35 The horizontal axis represents frequency f. Fig.35An example of allocating a synchronization signal (SS) to the entire frequency band BW is shown. 4401 represents a synchronization signal (SS) of a center frequency, and 4402 represents a synchronization signal (SS) configured with an additional SS at a frequency interval AFI. 4403 is data on a frequency used by a certain mobile terminal. A mobile terminal that demodulates the data of 4403 does not need to use the synchronization signal (SS) 4401 of the center frequency to obtain synchronization, but can use the additional synchronization signal (SS) 4402 adjacent to the data to obtain synchronization, and can achieve communication by only corresponding to a narrow frequency.

[0428] As a method of configuring the synchronization signal (SS), the position of the synchronization signal (SS) can be freely changed using a configuration file (configuration file). For example, in a base station that does not need to accommodate a large number of mobile terminals that only correspond to a narrow frequency band as in an MMC environment, the synchronization signal (SS) is configured only at the center frequency, and in a base station that needs to accommodate a large number of mobile terminals that only correspond to a narrow frequency band as in an MMC environment, the synchronization signal (SS) is configured over the entire frequency band or a wide frequency band.

[0429] As an example of a structural file, there is recorded the frequency of the subcarrier allocated to the synchronization signal (SS) as information in the frequency direction allocated by the synchronization signal (SS) and the frequency allocation period (for example, a 20MHz period) of the synchronization signal (SS) possessed by each base station, or the time position (subframe position, etc.) allocated by the synchronization signal (SS) as information in the time direction and the allocation period (for example, a 10ms period) of the synchronization signal (SS) in the time direction. When each base station is started, the above information is read from the file and applied to the allocation settings of the synchronization signal and the notification information of the broadcast information.

[0430] It can also be set from the MME / S-GW of the upper device of the base station to replace the configuration file. In this case, the synchronization signal allocation information of the surrounding cells in the Assisted configuration such as CA (Carrier Aggregation) and DC (Dual Connectivity) can also be set from the MME / S-GW, without the need for notification between base stations, which can simplify the control interface.

[0431] Fig.36 is a diagram showing another example of the arrangement of the synchronization signal (SS) in the frequency band. Fig.36 The horizontal axis represents frequency f. Fig.36An example is shown in which a synchronization signal (SS) is configured only for the allocated frequency band for MMC. In this example, an additional synchronization signal (SS) is not configured for the entire frequency band BW, but an additional synchronization signal (SS) 4503 is configured only for the frequency band used by MMC, as the SS configuration frequency AF for MMC. Thus, since the synchronization signal (SS) is not configured in the frequency band used by a mobile terminal that can usually transmit and receive wideband data, there is no need to configure a useless synchronization signal (SS).

[0432] There are two methods for synchronizing a mobile terminal to a base station. One is purposeless detection, and the other is the following method: in an Assisted structure such as CA (Carrier Aggregation) and DC (Dual Connectivity), when connected to SCell and SeNB (Secondary eNB), the frequency of the subcarriers allocated by the synchronization signal (SS) and the frequency allocation period (e.g., 20MHz period) of the synchronization signal (SS) are obtained from PCell and MeNB (Master eNB) as information on the frequency direction allocated by the synchronization signal (SS), or the time position (subframe position, etc.) of the synchronization signal (SS) allocated as information on the time direction and the allocation period (e.g., 10ms period) of the synchronization signal (SS) in the time direction.

[0433] The allocation information of the synchronization signal of SCell and SeNB can be included in the broadcast information as the surrounding cell information of PCell and MeNB. In addition, the SIB information of SCell and SeNB can also be notified using the broadcast information of PCell and MeNB. Therefore, regarding the communication between SCell and SeNB, after synchronization, the mobile terminal does not need to obtain the SIB information of SCell and SeNB, and only needs to perform processing corresponding to the frequency band used in data communication, which can simplify the device and reduce costs. In addition, since there is no SIB acquisition processing for SCell and SeNB, it also has the effect of being able to start data communication immediately.

[0434] In the case of non-target detection, the synchronization signal (SS) of the frequency band used for data communication is first searched, and when the synchronization signal (SS) is captured, the synchronization signal (SS) is used for frame synchronization and communication control. If the synchronization signal (SS) of the frequency band cannot be captured, the synchronization signal (SS) of the center frequency is used to perform synchronization with the base station.

[0435] In the case of the Assisted structure, the mobile terminal uses the main base station to obtain the information (frequency, time) of the insertion position of the added cell and the synchronization signal (SS) for the CC. For example, it is notified as a neighboring cell list (Neighboring Cell List) of the RRC information. Then, the search process of the synchronization signal (SS) is performed with the corresponding frequency and time of the added cell and CC.

[0436] Fig.37 This is a flowchart showing the processing steps of the communication terminal related to the synchronization signal detection process. Fig.37 Each process of the flowchart shown is executed by the communication terminal. If the communication terminal starts the cell search, it starts Fig.37 The processing of the flowchart shown is transferred to step ST4601.

[0437] In step ST4601, the communication terminal determines whether it is an Assisted structure. If it is determined to be an Assisted structure, the communication terminal proceeds to step ST4602, and if it is determined not to be an Assisted structure, the communication terminal proceeds to step ST4604.

[0438] In step ST4602, the communication terminal confirms whether the frequency band (hereinafter sometimes referred to as "synchronization signal (SS) insertion band") into which the synchronization signal (SS) of the additional cell (hereinafter sometimes referred to as "additional cell") is inserted is designated by the master base station. Specifically, the communication terminal determines whether the synchronization signal (SS) insertion band is designated by determining whether synchronization signal insertion band information indicating the synchronization signal (SS) insertion band can be obtained.

[0439] If it is determined that the synchronization signal (SS) insertion band is specified, the process proceeds to step ST4603; if it is determined that it is not specified, the process proceeds to step ST4604.

[0440] In step ST4603, the communication terminal performs synchronization processing using the synchronization signal (SS) of the designated frequency band.

[0441] When it is determined in step ST4601 that it is not an Assisted structure, and when the synchronization signal (SS) insertion band information of the additional cell cannot be obtained in step ST4602 and it is determined that the synchronization signal (SS) insertion band is not specified, the communication terminal performs aimless detection in steps ST4604 to ST4606.

[0442] First, in step ST4604, the communication terminal uses the synchronization signal (SS) of the frequency band used in data communication to try synchronization processing. In step ST4605, the communication terminal determines whether synchronization is completed. If it is determined that synchronization is completed, the synchronization processing of the synchronization signal (SS) is terminated and the RS detection and data communication are transferred. If it is determined that synchronization cannot be achieved, the synchronization processing is performed using the synchronization signal (SS) of the center frequency of the frequency band used for data communication. After that, the synchronization processing of the synchronization signal (SS) is terminated and the RS detection and data communication are transferred.

[0443] The synchronization signal (SS) of the center frequency is inserted in the minimum time unit (e.g., 1 ms period) because it is commonly used. However, as a method of inserting the synchronization signal (SS) other than the center frequency, it can be sparsely transmitted (e.g., 1 second period) in accordance with the mobile terminal accommodated. For example, the synchronization signal (SS) other than the center frequency is used by a mobile terminal such as MTC, so that time can be spent on synchronization capture time, and thus a synchronization signal (SS) with a long period can be used. In this case, by transmitting the synchronization signal (SS) other than the center frequency with a long period, it is possible to reduce the resources of the synchronization signal (SS) and increase the wireless resources that can be allocated to data transmission.

[0444] Fig.38 This is a diagram showing an example of a method of arranging a synchronization signal (SS) in the frequency direction. Fig.38 The horizontal axis represents frequency f, and the vertical axis represents time t. The synchronization signal (SS) 4701 of the center frequency is transmitted, for example, every 10 ms. The MMC-1 synchronization signal (SS) 4702 specifies and configures the frequency band for accommodating mobile terminals operating at a lower period. The MMC-1 SS configuration frequency AF1 is configured, for example, with a synchronization signal (SS) at a period of 40 ms.

[0445] The MMC-2 synchronization signal (SS) 4703 specifies and configures the MMC-2 SS configuration frequency AF2 for the frequency band that accommodates mobile terminals that operate at a higher period, for example, with a 20ms period. The additionally configured synchronization signal (SS) 4702 and synchronization signal (SS) 4703 can be sent at the same timing as the center frequency. The configuration of the synchronization signal (SS) 4702 is an example. In this case, in the Assisted structure, etc., the main base station uses the center frequency to obtain synchronization, and in the added cell, the synchronization signal (SS) is detected only at the timing after synchronization with the center period, thereby saving power consumption.

[0446] In addition, it can be offset in the time direction as in the synchronization signal (SS) 4703. In this case, by reducing the allocation occupancy rate of the synchronization signal (SS) per time unit, resource allocation to the mobile terminal performing high-speed transmission can be accelerated. This is because when high-speed transmission is performed during the time occupied by the synchronization signal (SS), data cannot be allocated and may be reserved until the next time slot.

[0447] In a system that forms a beam using a multi-element antenna, it is also effective to change the configuration of the additional synchronization signal (SS) for each beam. For example, when communicating with a mobile terminal that moves at high speed or using a thinner beam, the proportion of the additional synchronization signal (SS) in the time direction is increased or the synchronization signal (SS) insertion period in the frequency direction is shortened, so that the mobile terminal can be easily synchronized.

[0448] The structure disclosed in this embodiment can be used as a synchronization signal (SS) for network listening by a base station to detect base stations in neighboring cells.

[0449] In addition, when the base station sends a measurement configuration (measurement configuration) (RRC) and the mobile terminal sends a measurement report (measurement report) (RRC) according to the setting, by applying the structure disclosed in this embodiment, only the SS configuration frequency band is used as the measurement object, which can reduce the processing load of the mobile terminal.

[0450] Implementation method 8.

[0451] In the fifth generation, a large number of base stations capable of large-capacity communications outdoors are required. Wired lines, especially optical lines, are mainly laid indoors or underground, and it is sometimes difficult to lay the devices required for the optical communication interface on the walls of buildings and telecommunication poles. In addition, simple repeaters have the following problems: when a large number of base stations are installed, simple repeaters cannot adapt to changes in the wireless environment and cannot fully reduce interference.

[0452] Fig.39 FIG. 8 is a diagram showing a configuration of a communication system according to an eighth embodiment of the present invention. Fig.39 An example of installing a base station in a telecommunication pole where an optical communication device cannot be installed will be described.

[0453] SGW and MME (hereinafter referred to as "SGW / MME") 5001 is connected to base station (hereinafter sometimes referred to as "BS") 5002 and BS5003, exchanges data with each BS, and performs control management of each BS. BS5002 communicates with mobile terminals (UE) in the area of ​​the station, and communicates with BS5003. The antenna of BS5003 forms directional beams 5007 and 5008.

[0454] Originally, all the information required by BS5003 is transmitted and received from BS5002 via wireless. By using the wireless interface described later and using it in a manner that does not interfere with directional beams, time, and space resources, it is possible to install a base station without laying optical communication equipment.

[0455] Fig.40 : is a block diagram showing the structure of a communication system according to Embodiment 8 of the present invention. Fig.40 A method for connecting a base station via wireless is described. The communication system of this embodiment is configured to include SGW / MME5001, BS5002, BS5003, UE5004, 5005, and 5006. BS5002 includes a base station transmission processing unit 5101 and a base station reception processing unit 5102. BS5003 includes a reception antenna unit 5103, a base station mode reception processing unit 5105, a mobile terminal mode reception processing unit 5106, a base station management control unit 5107, a base station mode transmission processing unit 5108, a mobile terminal mode transmission processing unit 5109, a transmission antenna unit 5110, and a scheduler 5111.

[0456] The SGW / MME 5001 and the BS 5002 are connected using the S1 interface in LTE / LTE-A. The signal input from the SGW / MME 5001 is sent and processed by the base station transmission processing unit 5101 of the base station 5002 as data (DSCH) of the user plane (U-plane).

[0457] In the base station 5003, the receiving antenna unit 5103 preferably performs beam control to direct the directivity toward the base station 5002 according to the instruction 5124 of the scheduler 5111. In addition, according to the instruction 5118 of the scheduler 5111, the signal determined to be data transmitted from the base station 5002 is provided to the mobile terminal mode reception processing unit 5106.

[0458] The mobile terminal mode reception processing unit 5106 performs the same signal processing as the downlink signal reception processing performed by UE5004, 5005, 5006, such as decoding processing. In addition, in the mobile terminal mode reception processing unit 5106, the reception quality or feedback information 5119 of the reception quality of the receiving base station 5002 is measured and provided to the scheduler 5111.

[0459] The signal 5115 processed in the mobile terminal mode reception processing unit 5106 is provided to the base station mode transmission processing unit 5108. The base station mode transmission processing unit 5108 performs the same signal processing as the base station transmission processing unit 5101 of the BS 5002, such as encoding processing. In addition, the base station mode transmission processing unit 5108 performs resource mapping according to the instruction 5120 from the scheduler 5111, and transmits to the UE 5004, 5005, 5006 via the transmission antenna unit 5110.

[0460] At this time, the transmitting antenna unit 5110 preferably performs beam control to direct the directivity toward the UEs 5004, 5005, and 5006 according to the instruction 5125 of the scheduler 5111. The mobile terminal mode reception processing unit 5106 provides the base station management control unit 5107 with a signal 5112 determined to be a control signal such as maintenance management data of the base station, S1AP (S1 Application Protocol), or X2AP (X2 Application Protocol).

[0461] The signals transmitted from UE 5004 , 5005 , and 5006 are received by the receiving antenna unit 5103 of BS 5003 through a beam directed toward each UE according to an instruction 5124 from the scheduler 5111 .

[0462] According to the instruction 5116 of the scheduler 5111 , the signal determined to be data transmitted from UE 5004 , 5005 , 5006 is provided to the base station mode reception processing unit 5105 .

[0463] The base station mode reception processing unit 5105 performs the same signal processing as the uplink signal reception processing performed by the base station, such as decoding processing, etc. In addition, the base station mode reception processing unit 5105 measures the reception quality, or receives feedback information 5117 of the reception quality of UE5004, 5005, 5006, and provides it to the scheduler 5111.

[0464] The signal 5114 processed in the base station mode reception processing unit 5105 is provided to the mobile terminal mode transmission processing unit 5109. The mobile terminal mode transmission processing unit 5109 performs the same signal processing as the UE, such as encoding processing, based on the maintenance management data of the base station, S1AP, X2AP and other control signals 5113. In addition, the mobile terminal mode transmission processing unit 5109 performs resource mapping based on the instruction 5122 from the scheduler 5111, and provides it to the BS5002 via the transmission antenna unit 5110.

[0465] At this time, in the transmitting antenna unit 5110 , it is preferred that beam control be performed so that the directivity is directed toward the BS 5002 according to the instruction 5125 of the scheduler 5111 .

[0466] As described above, according to the communication system of this embodiment, even when a large number of base stations are installed, the number of base stations can be increased easily.

[0467] The wireless interface methods between BS5002 and BS5003 are divided into the following three methods: a method for transmitting backhaul signals (hereinafter sometimes referred to as "backhaul signal transmission method"), a method for transmitting signals between MeNB and SeNB using dual-line transmission (hereinafter sometimes referred to as "dual-line signal transmission method"), and a method for transmitting fronthaul signals (hereinafter sometimes referred to as "fronthaul signal transmission method"). The differences in the functional block diagrams of the three signal transmission methods are as follows: Figures 41 to 54 shown.

[0468] Fig.41 It is a block diagram showing the structure of the base station transmission processing unit 5101 when the backhaul signal transmission method is used. When using the return signal transmission method, the base station sending processing unit 5101 includes: an IP unit 5201, a UDP (User Datagram Protocol) / SCTP (Stream Control Transmission Protocol) / TCP (Transmission Control Protocol) unit 52021, a GTP-U (General Packet Radio Service Tunneling Protocol for User Plane) unit 5203, a PDCP (Packet Data Convergence Protocol) unit 52041, an RLC (Radio Link Control) unit 5205, a MAC (Medium Access Control) unit 5206, a CRC assignment unit 5207, a channel coding (Ch coding) unit 5208, a modulation unit 5209, a precoding (Precoding) unit 5210, an OFDM (Orthogonal Frequency Division Multiplexing) unit 5211 and a wireless sending processing unit 5212.

[0469] Fig.42This is a block diagram showing the structure of the base station transmission processing unit 5101 when the dual-link signal transmission method is used. It includes an IP unit 5201, a UDP / SCTP / TCP unit 52022, a GTP-U unit 5203, a PDCP corresponding unit 52242, an RLC unit 5205, a MAC unit 5206, a CRC assignment unit 5207, a channel coding (Ch coding) unit 5208, a modulation unit 5209, a precoding (Precoding) unit 5210, an OFDM unit 5211, and a wireless transmission processing unit 5212. The PDCP corresponding unit 52242 has a function equivalent to the PDCP unit.

[0470] Fig.43 This is a block diagram showing the structure of the base station transmission processing unit 5101 when the fronthaul signal transmission method is used. It includes an IP unit 5201, a UDP / SCTP / TCP unit 52023, a GTP-U unit 5203, a PDCP corresponding unit 52041, an RLC unit 5205, a MAC unit 5206, a CRC assignment unit 5207, a channel coding (Ch coding) unit 5208, a modulation unit 5209, a precoding (Precoding) unit 5210, an OFDM unit 5211 and a wireless transmission processing unit 5212.

[0471] Fig.44 This is a block diagram showing the structure of the base station reception processing unit 5102 when the backhaul signal transmission method is used. It includes a wireless reception processing unit 5213, an OFDM unit 5214, a postcoding unit 5215, a demodulation unit 5216, a channel coding (ChDecoding) unit 5217, a CRC check unit 5218, a MAC unit 5219, an RLC unit 5220, a PDCP unit 52211, a GTP-U unit 5222, a UDP / SCTP / TCP unit 52231 and an IP unit 5224.

[0472] Fig.45 This is a block diagram showing the structure of the base station reception processing unit 5102 when the dual-link signal transmission method is used. It includes a wireless reception processing unit 5213, an OFDM unit 5214, a post-coding unit 5215, a demodulation unit 5216, a channel coding (Ch Decoding) unit 5217, a CRC check unit 5218, a MAC unit 5219, an RLC unit 5220, a PDCP corresponding unit 52212, a GTP-U unit 5222, a UDP / SCTP / TCP unit 52232 and an IP unit 5224.

[0473] Fig.46This is a block diagram showing the structure of the base station reception processing unit 5102 when the fronthaul signal transmission method is used. It includes a wireless reception processing unit 5213, an OFDM unit 5214, a postcoding unit 5215, a demodulation unit 5216, a channel coding (ChDecoding) unit 5217, a CRC check unit 5218, a MAC unit 5219, an RLC unit 5220, a PDCP unit 52211, a GTP-U unit 5222, a UDP / SCTP / TCP unit 52233 and an IP unit 5224.

[0474] Fig.47 : is a block diagram showing the structure of the base station mode reception processing unit 5105. The base station mode reception processing unit 5105 includes a wireless reception processing unit 5213, an OFDM unit 5214, a post-coding unit 5215, a demodulation unit 5216, a channel coding (Ch Decoding) unit 5217, a CRC check unit 5218, a MAC unit 5219, an RLC unit 5220, and a PDCP unit 5221.

[0475] Fig.48 This is a block diagram showing the structure of the mobile terminal mode reception processing unit 5106 when the backhaul signal transmission method is used. It includes a wireless reception processing unit 5313, an OFDM unit 5314, a postcoding unit 5315, a demodulation unit 5316, a channel coding (Ch Decoding) unit 5317, a CRC check unit 5318, a MAC unit 5319, an RLC unit 5320, and a PDCP unit 5321.

[0476] Fig.49 This is a block diagram showing the structure of the mobile terminal mode reception processing unit 5106 when the dual link signal transmission method is used. It includes a wireless reception processing unit 5313, an OFDM unit 5314, a post-coding unit 5315, a demodulation unit 5316, a channel coding (Ch Decoding) unit 5317, a CRC check unit 5318, a MAC unit 5319, an RLC unit 5320, and a PDCP corresponding unit 5322.

[0477] Fig.50 This is a block diagram showing the structure of the mobile terminal mode reception processing unit 5106 when the backhaul signal transmission method is used. It includes a wireless reception processing unit 5313 and an OFDM unit 5314.

[0478] Fig.51This is a block diagram showing the structure of the base station mode transmission processing unit 5108 when the backhaul signal transmission method is used. It includes a PDCP unit 5304, an RLC unit 5305, a MAC unit 5306, a CRC assignment unit 5307, a channel coding (Ch coding) unit 5308, a modulation unit 5309, a precoding (Precoding) unit 5310, an OFDM unit 5311 and a wireless transmission processing unit 5312.

[0479] Fig.52 This is a block diagram showing the structure of the base station mode transmission processing unit 5108 when the dual-link signal transmission method is used. It includes a PDCP corresponding unit 5303, an RLC unit 5305, a MAC unit 5306, a CRC assignment unit 5307, a channel coding (Ch coding) unit 5308, a modulation unit 5309, a precoding (Precoding) unit 5310, an OFDM unit 5311 and a wireless transmission processing unit 5312.

[0480] Fig.53 This is a block diagram showing the configuration of the base station mode transmission processing unit 5108 when the fronthaul signal transmission method is used. It includes an OFDM unit 5311 and a wireless transmission processing unit 5312.

[0481] Fig.54 1 is a block diagram showing the structure of the mobile terminal mode transmission processing unit 5109. The mobile terminal mode transmission processing unit 5109 includes a PDCP unit 5324, an RLC unit 5325, a MAC unit 5326, a CRC assignment unit 5327, a channel coding (Ch coding) unit 5328, a modulation unit 5329, a precoding (Precoding) unit 5330, an OFDM unit 5331 and a wireless transmission processing unit 5332.

[0482] First of all, Figures 41 to 46 The difference between the base station transmission processing unit 5101 of BS5002 is described below.

[0483] In the backhaul signal transmission mode, when BS5003 is connected to SGW / MME5001 using an optical line, signals that can be used as base station actions, specifically S1AP signals, S1-U signals, X2AP signals, X2-U signals, and maintenance device inter-signals, are processed into wireless signals and sent wirelessly from BS5002. For example, if Fig.41If the UDP / SCTP / TCP part 52021 is UDP (User Datagram Protocol), it is determined to be an S1-U signal or an X2-U signal, and the port number is used to separate each user. For example, it is associated with the wireless resource ID such as the user ID. They use the GTP-U part 5203 to process GTP-U (GPRS (General Packet Radio Service) Tunneling Protocol for User Plane).

[0484] Next, if the UDP / SCTP / TCP unit 52021 is SCTP, it is associated with the S1AP signal or X2AP signal for each session. These data are also used as a user, and all parameters required in PDCP~L1 are generated, and PDCP processing is performed in the PDCP unit 52041.

[0485] Similarly, if the UDP / SCTP / TCP unit 52021 is TCP, it is determined to be a maintenance signal, and as a type of user, all parameters required in PDCP~L1 are generated, and PDCP processing is performed in the PDCP unit 52041.

[0486] The remaining IP (Internet Protocol) unit 5201 and RLC (Radio Link Control) unit 5205 to the wireless transmission processing unit 5212 are the same in all the modes.

[0487] Similarly, in the base station reception processing unit 5102 of BS5002, each method differs in that the opposite processing to the above is performed. Fig.44 After PDCP processing is performed in the PDCP 52211, the association with the radio resources is reversely searched and returned to the UDP / SCTP / TCP unit 52231. The other IP unit 5224 and the radio reception processing unit 5213 to the RLC unit 5220 are the same in all the methods.

[0488] In the dual-line signal transmission mode, all signals transmitted between MeNB and SeNB, specifically XnAP signals, Xn-U signals [equivalent to PDCP], and signals between maintenance devices are processed into wireless signals and sent wirelessly from BS5002. Due to the different corresponding signals, Fig.42 The UDP / SCTP / TCP portion 52022 is processed differently from the return signal transmission method.

[0489] The difference from the backhaul signal transmission method lies not in PDCP, but in the functions equivalent to PDCP, such as new control plane (C-Plane) control generated by device division, uplink sequence control, etc.

[0490] Similarly, in the base station reception processing unit 5102 of the base station 5002, each method differs in that the opposite processing to the above is performed. Fig.45 After the PDCP corresponding part 52212 performs the PDCP corresponding processing, the association with the radio resource is reversely searched and returned to the UDP / SCTP / TCP part 52232. The other IP part 5224 and the radio reception processing part 5213 to the RLC part 5220 are the same in all the methods.

[0491] In the fronthaul signal transmission mode, L1 signals and maintenance device inter-signal are processed into wireless signals and sent wirelessly from BS5002. L1 signals are, for example, downlink DA input signals and uplink AD output signals, or downlink pre-coded signals and uplink pre-coded signals, or L1-MAC signals. Fig.43 The UDPTCP part 52023 is handled differently from the return signal transmission method.

[0492] Similarly, in the base station reception processing unit 5102 of BS5002, each method differs in that the opposite processing to the above is performed. Fig.46 After PDCP processing is performed in the PDCP 52211, the association with the radio resources is reversely searched and returned to the UDP / TCP unit 52233. The other IP unit 5224 and the radio reception processing unit 5213 to the RLC unit 5220 are the same in all the methods.

[0493] Figures 47 to 53 The base station mode reception processing unit 5105, the mobile terminal mode reception processing unit 5106, the base station mode transmission processing unit 5108, and the mobile terminal mode transmission processing unit 5109 of the BS 5003 are shown. Regarding the fronthaul signal transmission method, an example of a functional block after the downlink precoding and the uplink postcoding signal is converted into a wireless signal is shown.

[0494] As described in detail above, in the resource management functional unit of each scheme, the signals between BS5002 and BS5003 and the signals between BS and UE can be multiplexed in time, frequency, and space within the same wireless frequency band.

[0495] For example, although UE5006 and BS5002 have the same direction and cannot be separated spatially, stable communication can be provided by using resource area 5011 separated in time and frequency.

[0496] In addition, between BS5002 and BS5003, even if the surrounding radio interference increases and a certain frequency cannot be used, as long as it is near BS5003, the frequency can be used with less radio interference. In this case, unlike the repeater, stable communication with the mobile terminal can be achieved by flexibly allocating wireless resources.

[0497] In addition, in order to realize the backhaul signal transmission method, the following method is effective.

[0498] The first method is to wirelessly transmit part or all of the five signals (S1AP signal, S1-U signal, X2AP signal, X2-U signal, and maintenance device signal) input to the base station 5003 as one mobile terminal. Wireless encryption processing is also integrated into one. For example, it is known that regarding the directivity control of the antenna, the communication object is one, so it is not necessary to process each signal.

[0499] The second method is a method of wirelessly transmitting the five types of signals input to the base station 5003 as an independent mobile terminal. It is a method of having an ID equivalent to an independent mobile terminal, performing additional wireless encryption, and transmitting and receiving based on wireless transmission procedures (PDCP, RLC, MAC) with different parameters. There is no need to use the function of the base station to merge signals with different connection destinations. Therefore, for example, for the increase or decrease in the number of connected surrounding base stations (the number of connected X2 roots), the signal can be added or deleted.

[0500] The dual-line signal transmission method is the same as the return signal transmission method. It is effective to use part or all of the three signals (XnAP signal, Xn-U signal [equivalent to PDCP], and maintenance device signal) as a mobile terminal for wireless transmission, and as an independent mobile terminal.

[0501] The fronthaul signal transmission method is the same as the backhaul signal transmission method. It is effective to wirelessly transmit two types of signals (L1 signal and maintenance device signal) as one mobile terminal or as an independent mobile terminal.

[0502] Implementation 8 Variation 1.

[0503] A method for using a base station even when a wired line is cut off due to a disaster or the like and the base station cannot be used is disclosed.

[0504] Regarding BS5003 of the eighth embodiment, in addition to the functions of the eighth embodiment that can eliminate the need for a wired line, the following function can be provided: when the wire of the own station is disconnected or a base station that is normally operated without a wired line detects that the connection with the base station that is normally connected is disconnected, the surrounding cell that is the same as the mobile terminal is searched. Regarding the wire disconnection, the judgment can be made based on the disappearance of a signal that can confirm that the line is in a normal state, such as the heartbeat of TCP and SCTP, or the LOF (Loss of Frame) of the Ethernet (registered trademark) level can be used.

[0505] Furthermore, the following function may be provided: when performing a search, the number of elements of the multi-element antenna is increased to increase the equivalent isotropic radiated power (EIRP).

[0506] In addition, a function of self-diagnosis can be provided to determine whether a wired connection can be used during recovery. It is also effective to use a function of sending data instead of a return reception test. A function can be provided to periodically send a signal indicating that the self-diagnosis result is good. It is effective to set this signal to be different from a P-SS or S-SS signal. In this case, the transmission can be performed while changing the directivity using a multi-element antenna.

[0507] In addition, the following functions may be provided: when a backhaul, a dual-wired interface or a fronthaul capable of wireless connection is found, a plug-and-play connection process is executed.

[0508] In addition, when starting to communicate with neighboring cells, since audio becomes the main communication method in a disaster, it is also effective to have a function to improve the required BLER (Block Error Rate) which is the basis for MCS (Modulation and channel Coding Scheme) and transmission power control. The required BLER is, for example, 10-6, and by using the function to improve the required BLER, it can be improved to, for example, 10-2.

[0509] In the eighth embodiment, BS5002 can be provided with a function of searching for cells in the surrounding area that are disconnected from the wired line, in addition to the function of BS5003 that eliminates the need for a wired line. Reception can be performed while changing the directivity by utilizing the time and frequency when communication is not in use.

[0510] In addition, the following function can be provided: although it is possible to detect cells in the surrounding area that are in a wired disconnected state, when the wired line cannot be restored, the service area of ​​the own station is expanded and beam allocation is performed toward the cells in the surrounding area that are in a wired disconnected state.

[0511] Even if the base station 5002 is a so-called capacity cell, a function may be provided to transmit a common channel to the beam even when a common channel such as a broadcast channel is not transmitted during normal operation.

[0512] The above-mentioned embodiments and their modifications are merely examples of the present invention, and the embodiments and their modifications can be freely combined within the scope of the present invention. In addition, arbitrary components of the embodiments and their modifications can be appropriately changed or omitted.

[0513] The present invention has been described in detail, but the above description is in all aspects illustrative and the present invention is not limited thereto. Numerous modifications not shown here are conceivable without departing from the scope of the present invention.

[0514] Description of symbols

[0515] 3201MME / S-GW unit, 3202eNB, 3203UE, 3204 cell, 3301ICBS, 3302RRE, 3303RRE cell, 3401 macro cell eNB, 3402 small cell eNB, 3403 macro cell, 3404 small cell.

Claims

1. A wireless communication system, wherein a plurality of subcarriers are used for wireless communication between a communication terminal and a base station, characterized in that: The base station notifies the communication terminal of a subcarrier interval for each time unit and frequency unit.

2. The wireless communication system according to claim 1, wherein: The interval of the subcarriers per time unit is notified from the base station to the communication terminal.

3. The wireless communication system according to claim 1, wherein: The interval of the subcarriers per frequency unit is notified from the base station to the communication terminal.

4. The wireless communication system according to claim 1, wherein: The base station is a first base station as a moving source of the handover or a second base station as a moving destination of the handover, The interval of the subcarriers is notified from the first base station to the second base station.

5. A base station, wherein the base station and a communication terminal use multiple subcarriers for wireless communication, characterized in that: The communication terminal is notified of the interval of subcarriers per time unit and frequency unit.

6. A communication terminal, wherein the communication terminal and a base station use multiple subcarriers for wireless communication, characterized in that: The subcarrier interval for each time unit and frequency unit notified by the base station is received.

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