Communication system

Abstract

A communication system includes a base station connected to a core network capable of providing an XR service, and a communication terminal connected to the base station, corresponding to a 5th generation wireless access system. A communication terminal notifies a base station of information related to characteristics of uplink data transmitted to the base station in communication for using an XR service.

Description

Technical Field

[0001] The present disclosure relates to wireless communication technology. Background Art

[0002] In 3GPP (3rd Generation Partnership Project), a standardization organization for mobile communication systems, the fifth generation (sometimes referred to as "5G") wireless access system is being discussed as a successor to Long Term Evolution (LTE) and Long Term Evolution Advanced (LTE-A), one of the fourth generation wireless access systems (see Non-Patent Document 1) (for example, Non-Patent Document 2). The technology for the wireless section of 5G is called "New Radio Access Technology" ("New Radio" is abbreviated as "NR"). The NR system is discussed based on the LTE system and the LTE-A system.

[0003] For example, in Europe, the METIS organization is summarizing the requirements for 5G (see non-patent document 3). In the 5G wireless access system, the system capacity is 1000 times that of the LTE system, the data transmission speed is 100 times, the data processing delay is 1 / 5, and the number of simultaneous connections of communication terminals is 100 times. The conditions for achieving further low power consumption and low cost of the device can be listed as requirements (see non-patent document 3).

[0004] In order to meet such requirements, discussions on 5G standards are progressing in 3GPP (see non-patent documents 4 to 23).

[0005] As the access method of NR, OFDM (Orthogonal Frequency Division Multiplexing) is used in the downlink direction, and OFDM and DFT-s-OFDM (Discrete Fourier Transform-spread-OFDM) are used in the uplink direction. In addition, like LTE and LTE-A, the 5G system does not include line switching, but only packet communication.

[0006] In NR, higher frequencies can be used compared to LTE to increase transmission speeds and reduce processing delays.

[0007] In NR, which sometimes uses higher frequencies than LTE, a narrower beam-shaped transmission and reception range is formed (beamforming) and the direction of the beam is changed (beam scanning), thereby attempting to ensure cell coverage.

[0008] use Figure 1 This article explains the decisions made by 3GPP regarding the frame structure of the NR system as described in Non-Patent Document 1 (Chapter 5). Figure 1 This is an explanatory diagram showing the structure of a wireless frame used in a communication system using the NR method. Figure 1 In NR, one radio frame is 10ms. The radio frame is divided into 10 subframes of equal size. The frame structure of NR supports one or more parameter sets (Numerology), that is, one or more subcarrier spacings (Subcarrier spacing: SCS). In NR, one subframe is 1ms, and one time slot consists of 14 code elements, regardless of the subcarrier spacing. In addition, the number of time slots contained in one subframe is one when the subcarrier spacing is 15kHz, and the number of time slots in other subcarrier spacings increases in proportion to the subcarrier spacing (refer to non-patent document 11 (3GPP TS38.211)).

[0009] Non-Patent Document 2 (Chapter 5) and Non-Patent Document 11 record the decisions made by 3GPP regarding the channel structure in the NR system.

[0010] The Physical Broadcast Channel (PBCH) is a channel used for downlink transmission from a base station device (hereinafter sometimes referred to as "base station") to a communication terminal device (hereinafter sometimes referred to as "communication terminal" or "terminal") such as a mobile terminal device (hereinafter sometimes referred to as "mobile terminal"). The PBCH is transmitted together with a downlink synchronization signal.

[0011] The downlink synchronization signal in NR has a first synchronization signal (Primary Synchronization Signal: P-SS) and a second synchronization signal (Secondary Synchronization Signal: S-SS). The synchronization signal is sent from the base station as a synchronization signal burst (Synchronization Signal Burst: sometimes referred to as SS burst below) at a specified period for a specified duration. The SS burst consists of a synchronization signal block (Synchronization Signal Block; sometimes referred to as SS block below) for each beam of the base station.

[0012] The base station changes the beam during the duration of the SS burst to transmit the SS block of each beam. The SS block consists of P-SS, S-SS and PBCH.

[0013] The Physical Downlink Control Channel (PDCCH) is a channel for downlink transmission from the base station to the communication terminal. PDCCH transmits downlink control information (DCI). DCI includes resource allocation information for the downlink shared channel (DL-SCH), one of the transmission channels described later, resource allocation information for the paging channel (PCH), one of the transmission channels described later, and HARQ (Hybrid Automatic Repeat reQuest) information related to DL-SCH. In addition, DCI sometimes includes uplink scheduling grant. DCI sometimes includes a response signal for uplink transmission, namely Ack (Acknowledgement) / Nack (Negative Acknowledgement). In addition, in order to flexibly switch DL / UL within a time slot, DCI sometimes includes a time slot format indication (Slot Format Indication: SFI). PDCCH or DCI is also called L1 / L2 control signal.

[0014] In NR, a time domain and a frequency domain are provided as candidates for including PDCCH. This area is called a control resource set (CORESET). The communication terminal monitors CORESET and acquires PDCCH.

[0015] 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.

[0016] The Physical Uplink Control Channel (PUCCH) is a channel for uplink transmission from the communication terminal to the base station. PUCCH transmits uplink control information (UCI). UCI includes response information (response signal) for downlink transmission, namely Ack / Nack, CSI (Channel State Information), scheduling request (SR), etc. CSI is composed of RI (Rank Indicator), PMI (Precoding Matrix Indicator), and CQI (Channel Quality Indicator) reports. RI refers to the rank information of the channel matrix in MIMO (Multiple Input Multiple Output). PMI refers to the information of the precoding waiting matrix used in MIMO. CQI is quality information indicating the quality of the received data or the quality of the communication line. UCI is sometimes transmitted through the PUSCH described later. PUCCH or UCI is also called L1 / L2 control signal.

[0017] The physical uplink shared channel (PUSCH) is a channel for uplink transmission from a communication terminal to a base station. An uplink shared channel (UL-SCH), which is one of the transport channels, is mapped to the PUSCH.

[0018] The Physical Random Access Channel (PRACH) is a channel for uplink transmission from a communication terminal to a base station. The PRACH transmits a random access preamble.

[0019] The downlink reference signal (Reference Signal: RS) is a codeword known as a communication system of the NR mode. The following four downlink reference signals are defined. The UE-specific Reference Signal (UE-specific Reference Signal) is the data demodulation reference signal (Demodulation Reference Signal: DM-RS), the phase tracking reference signal (Phase Tracking Reference Signal: PT-RS), the positioning reference signal (Positioning Reference Signal: PRS), and the channel state information reference signal (Channel State Information Reference Signal: CSI-RS). As a measurement of the physical layer of the communication terminal, there are reference signal received power (Reference Signal Received Power: RSRP) measurement and reference signal received quality (Reference Signal Received Quality: RSRQ) measurement.

[0020] The uplink reference signal is also a symbol known as a communication system of the NR method. The following three types of uplink reference signals are defined: data demodulation reference signal (Demodulation Reference Signal: DM-RS), phase tracking reference signal (Phase Tracking Reference Signal: PT-RS), and sounding reference signal (Sounding Reference Signal: SRS).

[0021] The transport channel described in Non-Patent Document 2 (Chapter 5) is described below. The broadcast channel (BCH) in the downlink transport channel is broadcast to the entire coverage area of ​​its base station (cell). The BCH is mapped to the physical broadcast channel (PBCH).

[0022] HARQ-based retransmission control 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 quasi-static resource allocation. Quasi-static resource allocation is also called semi-persistent scheduling. DL-SCH supports discontinuous reception (DRX) of communication terminals in order to reduce power consumption of communication terminals. DL-SCH is mapped to the physical downlink shared channel (PDSCH).

[0023] The Paging Channel (PCH) supports DRX of the communication terminal in order to reduce the power consumption of the communication terminal. The PCH can 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 used dynamically according to the traffic.

[0024] Retransmission control using HARQ is applied to the uplink shared channel (UL-SCH) in the uplink transmission channel. UL-SCH supports dynamic or quasi-static resource allocation. Quasi-static resource allocation is also called configured grant. UL-SCH is mapped to the physical uplink shared channel (PUSCH).

[0025] The Random Access Channel (RACH) is limited to control information. There is a risk of collision in the RACH. The RACH is mapped to the Physical Random Access Channel (PRACH).

[0026] 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). HARQ has the following advantages: 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.

[0027] 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.

[0028] Other examples of the retransmission method are described. When a CRC error occurs on the receiving side, a retransmission request is made from the receiving side to the sending side. The retransmission request is made by switching the NDI (New Data Indicator). The sending side that receives the retransmission request retransmits the data. When there is no CRC error on the receiving side, no retransmission request is made. When the sending side does not receive a retransmission request within a specified time, it is deemed that there is no CRC error on the receiving side.

[0029] 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).

[0030] The Paging Control Channel (PCCH) is a downlink channel for transmitting changes in paging information (PagingInformation) and system information (SystemInformation). The PCCH, which is a logical channel, is mapped to the Paging Channel (PCH), which is a transport channel.

[0031] 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.

[0032] Dedicated Control Channel (DCCH) is a channel used to send dedicated control information between a communication terminal and a network in a point-to-point manner. DCCH is used when there is an RRC connection between a communication terminal and a network. DCCH is mapped to the uplink shared channel (UL-SCH) in the uplink and to the downlink shared channel (DL-SCH) in the downlink.

[0033] Dedicated Traffic Channel (DTCH) is a channel used to send user information and perform point-to-point communication with communication terminals. 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.

[0034] 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, so as to call the communication terminal. In other words, it is performed to call the communication terminal. The area used for the location tracking of the communication terminal is called a tracking area (TA).

[0035] NR supports calling of communication terminals within a range smaller than the tracking area. This range is called RAN Notification Area (RNA). Paging of communication terminals in the RRC_INACTIVE state described later is performed within this range.

[0036] In order to support wider frequency bandwidths (transmission bandwidths), carrier aggregation (CA) of aggregating (also called "aggregation") two or more component carriers (CC) is being studied in NR. CA is described in Non-Patent Document 1.

[0037] In the case of CA, the UE as a communication terminal has a unique RRC connection with the network (Network: NW). In the RRC connection, one service cell provides NAS mobility information and security input. This cell is called the primary cell (Primary Cell: PCell). According to the capabilities of the UE (capability), a secondary service cell (Secondary Cell: SCell) is formed to form a group of service cells together with the PCell. For one UE, a group of service cells consisting of one PCell and one or more SCells is formed.

[0038] In addition, in 3GPP, there is a dual connectivity (DC) in which a UE is connected to two base stations for communication, in order to further increase the communication capacity. DC is described in Non-Patent Documents 1 and 22.

[0039] Sometimes one of the base stations performing dual connectivity (DC) is called the "master base station (Master Node: MN)", and the other is called the "secondary base station (Secondary Node: SN)". The service cells formed by the master base station are sometimes collectively referred to as the master cell group (Master Cell Group: MCG), and the service cells formed by the secondary base stations are sometimes collectively referred to as the secondary cell group (Secondary Cell Group: SCG). In DC, the main cell in the MCG or SCG is called a special cell (Special Cell: SpCel l or SPCell). The special cell in the MCG is called PCell, and the special cell in the SCG is called the primary SCG cell (PSCell).

[0040] In addition, in NR, the base station pre-sets a part of the carrier frequency band for the UE (hereinafter sometimes referred to as Bandwidth Part: bandwidth part (BWP)), and the UE transmits and receives between itself and the base station in the BWP, thereby being able to reduce power consumption in the UE.

[0041] In addition, in 3GPP, services (which may also be applications) that support the use of side link (SL) communication (also called PC5 communication) in both the EPS (Evolved Packet System) and the 5G core system described later are studied (refer to non-patent documents 1, 2, 26 to 28). In SL communication, communication is performed between terminals. As services that use SL communication, there are, for example, V2X (Vehicle-to-everything) services and proxy services. In SL communication, not only direct communication between terminals, but also communication between UE and NW via relay is proposed (refer to non-patent documents 26 and 28).

[0042] The physical channels used for SL are described below (see Non-Patent Documents 2 and 11). The physical sidelink broadcast channel (PSBCH) transmits information related to system synchronization and is sent from the UE.

[0043] The physical sidelink control channel (PSCCH) transmits control information from the UE for sidelink communication and V2X sidelink communication.

[0044] The physical sidelink shared channel (PSSCH) transmits data from the UE for sidelink communication and V2X sidelink communication.

[0045] The physical sidelink feedback channel (PSFCH) transmits HARQ feedback on the sidelink from the UE that receives the PSSCH transmission to the UE that sends the PSSCH.

[0046] The transport channel used for SL will be described below (see Non-Patent Document 1). The sidelink broadcast channel (SL-BCH) has a predetermined transport channel format and is mapped to the PSBCH which is a physical channel.

[0047] The sidelink shared channel (SL-SCH) supports broadcast transmission. SL-SCH supports both UE autonomous resource selection and resource allocation scheduled by the base station. There is a risk of conflict in UE autonomous resource selection, but there is no conflict when the UE is allocated dedicated resources through the base station. In addition, SL-SCH supports dynamic link adaptation by changing the transmission power, modulation, and combining. SL-SCH is mapped to PSSCH, which is a physical channel.

[0048] The logical channels used for SL are described below (see Non-Patent Document 2). The Sidelink Broadcast Control Channel (SBCCH) is a sidelink channel used to broadcast sidelink system information from one UE to other UEs. The SBCCH is mapped to the SL-BCH which is a transmission channel.

[0049] Sidelink Traffic Channel (STCH) is a one-to-many sidelink traffic channel used to send user information from one UE to other UEs. STCH is only used by UEs with sidelink communication capabilities and UEs with V2X sidelink communication capabilities. One-to-one communication between two UEs with sidelink communication capabilities is also achieved through STCH. STCH is mapped to SL-SCH, which is a transport channel.

[0050] A sidelink control channel (SCCH) is a sidelink control channel for transmitting control information from one UE to other UEs. The SCCH is mapped to the SL-SCH which is a transport channel.

[0051] In LTE, SL communication is only broadcast. In NR, in addition to broadcast, support for unicast and groupcast is also being studied as SL communication (see Non-Patent Document 27 (3GPP TS23.287)).

[0052] In SL's unicast and multicast communications, HARQ feedback (Ack / Nack), CSI reporting, etc. are supported.

[0053] In addition, 3GPP is studying Integrated Access and Backhaul (IAB) in which both an access link as a link between a UE and a base station and a backhaul link as a link between base stations are wirelessly performed (see Non-Patent Documents 2, 20, and 29).

[0054] In 3GPP, some new technologies have been proposed. For example, a communication method suitable for XR (eXtended Reality) or cloud gaming services has been discussed (non-patent document 30), and an XR identification method that takes into account the characteristics of XR traffic (XRTraffic) (such as non-integer periodicity, data generation time variation (jitter) characteristics, data volume variation characteristics, low latency characteristics, etc.), an XR-specific low power consumption method, and an XR-specific capacity improvement method have been proposed (non-patent documents 31, 32, 33). Prior art literature Non-patent literature

[0055] Non-patent document 1: 3GPP TS 36.300 V16.7.0 Non-patent document 2: 3GPP TS 38.300 V16.8.0 Non-patent document 3: “Scenarios, requirements and KPIs for 5G mobile and wireless system”, ICT-317669-METIS / D1.1 Non-patent document 4: 3GPP TR 23.799 V14.0.0 Non-patent document 5: 3GPP TR 38.801 V14.0.0 Non-patent document 6: 3GPP TR 38.802 V14.2.0 Non-patent document 7: 3GPP TR 38.804 V14.0.0 Non-patent document 8: 3GPP TR 38.912 V16.0.0 Non-patent document 9: 3GPP RP-172115 Non-patent document 10: 3GPP TS23.501V17.3.0 Non-patent document 11: 3GPP TS 38.211 V17.0.0 Non-patent document 12: 3GPP TS 38.212 V17.0.0 Non-patent document 13: 3GPP TS 38.213 V17.0.0 Non-patent document 14: 3GPP TS 38.214 V17.0.0 Non-patent document 15: 3GPP TS 38.321 V16.7.0 Non-patent document 16: 3GPP TS 38.322 V16.2.0 Non-patent document 17: 3GPP TS 38.323 V16.6.0 Non-patent document 18: 3GPP TS 37.324 V16.3.0 Non-patent document 19: 3GPP TS 38.331 V16.7.0 Non-patent document 20: 3GPP TS 38.401 V16.8.0 Non-patent document 21: 3GPP TS 38.413 V16.8.0 Non-patent document 22: 3GPP TS 37.340 V16.8.0 Non-patent document 23: 3GPP TS 38.423 V16.8.0 Non-patent document 24: 3GPP TS 38.305 V16.7.0 Non-patent document 25: 3GPP TS23.273V17.3.0 Non-patent document 26: 3GPP TR 23.703 V12.0.0 Non-patent document 27: 3GPP TS23.287V17.2.0 Non-patent document 28: 3GPP TS23.303V17.0.0 Non-patent document 29: 3GPP TS 38.340 V16.5.0 Non-patent document 30: 3GPP RP-213587 Non-patent document 31: 3GPP R1-2204656 Non-patent document 32: 3GPP R1-2203132 Non-patent document 33: 3GPP R1-2205056 Non-patent document 34: 3GPP TR38.838 V17.0.0 Summary of the invention Technical problem to be solved by the invention

[0056] In the 5G wireless access system, communications are performed for a variety of services. It is also an important issue to achieve communications suitable for XR and cloud gaming services. In order to enable such communications, a communication method that takes into account the characteristics of XR traffic (such as non-integer periodicity, data generation time variation (jitter) characteristics, data volume variation characteristics, low latency characteristics, etc.) is required (non-patent document 30). In existing communication methods, the NW side does not have a means to identify such characteristics of data generated on the UE side. Therefore, existing communication methods have the following problems: they are not suitable for the characteristics of XR traffic, resulting in increased delay time and deterioration of communication quality.

[0057] In view of the above problems, one of the objects of the present disclosure is to realize a communication system suitable for communication having characteristics such as XR traffic. Technical means for solving technical problems

[0058] The communication system disclosed in the present invention corresponds to a fifth-generation wireless access system, and includes a base station connected to a core network capable of providing XR services and a communication terminal connected to the base station. When the communication terminal uses the XR service via the base station, the communication terminal notifies the base station of information related to the characteristics of uplink data sent to the base station in communications used to use the XR service. Effects of the Invention

[0059] According to the present disclosure, a communication system suitable for communication having characteristics such as XR traffic can be realized.

[0060] The objects, features, aspects and advantages of the present disclosure will become more apparent from the following detailed description and accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0061] Figure 1 This is an explanatory diagram showing the structure of a wireless frame used in a communication system using the NR method. Figure 2 This is a block diagram showing the overall structure of the NR-based communication system 210 discussed in 3GPP. Figure 3 This is a structural diagram of the DC based on the base station connected to the NG core. Figure 4 Yes means Figure 2 A block diagram of the structure of the mobile terminal 202 is shown. Figure 5 Yes means Figure 2 A block diagram of the structure of the base station 213 is shown. Figure 6 It is a block diagram showing the structure of the 5GC unit. Figure 7 This is a flowchart showing an overview of the cell search and standby actions performed by a communication terminal (UE) in a communication system using the NR mode. Figure 8 is a diagram showing an example of a cell structure in an NR system. Fig. 9 It is a connection structure diagram showing an example of the connection structure of the terminal in SL communication. Fig.10 is a connection structure diagram showing an example of a connection structure of a base station supporting access backhaul integration. Fig.11 This is a diagram showing an example flow of a method for sending information related to UL data and preference information related to CG settings from UE to gNB regarding implementation mode 1. Fig.12 This is a diagram showing an example flow of a method for sending information related to UL data and DL data from a gNB to an AF according to implementation mode 1. DETAILED DESCRIPTION

[0062] Implementation method 1. Figure 2 2 is a block diagram showing the overall structure of a communication system 210 using the NR method discussed in 3GPP. Figure 2 For explanation. The radio access network is called NG-RAN (Next Generation Radio Access Network: Next Generation Radio Access Network) 211. The communication terminal device, namely 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 "NR base station (NG-RAN NodeB: gNB)") 213, and use wireless communication to send and receive signals. NG-RAN 211 is composed of one or more NR base stations 213.

[0063] Here, the "communication terminal device" includes not only mobile terminal devices such as mobile phone terminal devices that can be moved, but also non-mobile devices such as sensors. In the following description, the "communication terminal device" may be simply referred to as a "communication terminal".

[0064] The protocol of AS (Access Stratum) is terminated between UE 202 and NG-RAN 211. As the protocol of AS, for example, RRC (Radio Resource Control), SDAP (Service Data Adaptation Protocol), PDCP (Packet Data Convergence Protocol), RLC (Radio Link Control), MAC (Medium Access Control), and PHY (Physical layer) are used. RRC is used for the control layer (hereinafter, sometimes also referred to as C layer or C-Plane), SDAP is used for the user layer (hereinafter, sometimes also referred to as U layer or U-Plane), and PDCP, MAC, RLC, and PHY are used for both the C layer and the U layer.

[0065] The control protocol RRC (Radio Resource Control) between UE 202 and NR base station 213 performs broadcast, paging, RRC connection management, etc. The states between NR base station 213 and UE 202 in RRC include RRC_IDLE, RRC_CONNECTED, and RRC_INACTIVE.

[0066] In RRC_IDLE, PLMN (Public Land Mobile Network) selection, system information (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 (Handover: HO), measurement of neighbor cells, etc. are performed. RRC_INACTIVE maintains the connection between the 5G core unit 214 and the NR base station 213, while broadcasting system information (System Information: SI), paging, cell reselection, movement, etc.

[0067] The gNB 213 is connected to the 5G core unit (hereinafter sometimes referred to as the "5GC unit") 214 including the Access and Mobil ity Management Function (AMF), the Session Management Function (SMF), or the User Plane Function (UPF) through the NG interface. Communication of control information and / or user data is performed between the gNB 213 and the 5GC unit 214. The NG interface is a general term for the N2 interface between the gNB 213 and the AMF 220, the N3 interface between the gNB 213 and the UPF 221, the N11 interface between the AMF 220 and the SMF 222, and the N4 interface between the UPF 221 and the SMF 222. One gNB 213 can be connected to multiple 5GC units 214. The gNBs 213 are connected to each other through the Xn interface, and communication of control information and / or user data is performed between the gNBs 213.

[0068] The 5GC unit 214 is an upper device, specifically, an upper node, and controls the connection between the NR base station 213 and the mobile terminal (UE) 202, allocates paging signals to one or more NR base stations (gNB) 213 and / or LTE base stations (E-UTRAN NodeB: eNB), etc. In addition, the 5GC unit 214 performs mobility control (Mobility Control) in the idle state (Idle State). The 5GC unit 214 manages the tracking area (Tracking Area) list when the mobile terminal 202 is in the idle state and in the inactive state (Inactive State) and active state (Active State). The 5GC unit 214 starts the paging protocol by sending a paging message to the cell belonging to the tracking area (Tracking Area) where the mobile terminal 202 is registered (registered).

[0069] gNB 213 can constitute one or more cells. In the case where one gNB 213 constitutes multiple cells, each cell is configured to be able to communicate with UE 202.

[0070] The gNB 213 can be divided into a central unit (Central Unit: sometimes referred to as CU below) 215 and a distributed unit (Distributed Unit: sometimes referred to as DU below) 216. CU 215 is configured as one in gNB 213. DU 216 is configured as one or more in gNB 213. One DU 216 constitutes one or more cells. CU 215 is connected to DU 216 via an F1 interface, and control information and / or user data are communicated between CU 215 and DU 216. The F1 interface is composed of an F1-C interface and an F1-U interface. CU 215 assumes the functions of each protocol of RRC, DSAP, and PDCP, and DU 216 assumes the functions of each protocol of RLC, MAC, and PHY. One or more TRPs (Transmission Reception Points: sending and receiving points) 219 are sometimes connected to DCU 216. TR 219 transmits and receives wireless signals with UE.

[0071] The CU 215 may be divided into a C-layer CU (CU-C) 217 ​​and a U-layer CU (CU-U) 218. The CU-C 217 is configured as one in the CU 215. The CU-U 218 is configured as one or more in the CU 215. The CU-C 217 is connected to the CU-U 218 via an E1 interface, and control information is communicated between the CU-C 217 and the CU-U 218. The CU-C 217 is connected to the DU 216 via an F1-C interface, and control information is communicated between the CU-C 217 and the DU 216. The CU-U 218 is connected to the DU 216 via an F1-U interface, and user data is communicated between the CU-U 218 and the DU 216.

[0072] The 5G communication system may include the Unified Data Management (UDM) function and the Policy Control Function (PCF) described in Non-Patent Document 10 (3GPP TS23.501). UDM and / or PCF may be included in Figure 2 In the 5GC section 214.

[0073] In a 5G communication system, a location management function (LMF) described in non-patent document 24 (3GPP TS38.305) may be provided. As disclosed in non-patent document 25 (3GPP TS23.273), the LMF may be connected to a base station via an AMF.

[0074] The 5G communication system may include a non-3GPP interworking function (N3IWF) described in non-patent document 10 (3GPP TS23.501). The N3IWF can terminate the access network (AN) between the UE and the UE in the non-3GPP access between the UE and the UE.

[0075] Figure 3 This is a diagram showing a structure based on DC (dual connection) connected to the NG core. Figure 3 In the figure, the solid line represents the connection of U-Plane, and the dotted line represents the connection of C-Plane. Figure 3 In the example, the primary base station 240-1 can be a gNB or an eNB. In addition, the secondary base station 240-2 can be a gNB or an eNB. Figure 3 In the present invention, the DC structure in which the primary base station 240-1 is a gNB and the secondary base station 240-2 is an eNB is sometimes referred to as NG-EN-DC. Figure 3 In the example, the U-Plane connection between the 5GC unit 214 and the auxiliary base station 240-2 is performed via the main base station 240-1, but it can also be performed directly between the 5GC unit 214 and the auxiliary base station 240-2. Figure 3 In the present invention, the core network connected to the LTE system and the LTE-A system, namely the EPC (Evolved Packet Core), can be connected to the main base station 240-1 instead of the 5GC unit 214. The U-Plane connection between the EPC and the auxiliary base station 240-2 can be performed directly.

[0076] Figure 4 Yes means Figure 2 The structure of the mobile terminal 202 is shown in FIG. Figure 41 and 2. The transmission processing of the mobile terminal 202 shown in FIG. 2 is described. First, the control data from the control unit 310 and the user data from the application unit 302 are sent to the protocol processing unit 301. The control data and the user data can be buffered. The buffering of the control data and the user data can be set in the control unit 310, the application unit 302, or the protocol processing unit 301. The protocol processing unit 301 performs protocol processing such as SDAP, PDCP, RLC, MAC, etc., for example, it performs actions such as determining the transmission target base station in DC, etc., and assigning headers in each protocol. The data that has undergone protocol processing is transmitted to the encoding unit 304, and encoding processing such as error correction processing is performed. There may also be data that is directly output from the protocol processing unit 301 to the modulation unit 305 without performing encoding processing. The data encoded by the encoding unit 304 is modulated in the modulation unit 305. Precoding in MIMO can also be performed in the modulation unit 305. After the modulated data is converted into a baseband signal, it is output to the frequency conversion unit 306 and converted into a wireless transmission frequency. After that, the transmission signal is transmitted from antennas 307-1 to 307-4 to base station 213. Figure 4 , the example shows a case where the number of antennas is 4, but the number of antennas is not limited to 4.

[0077] In addition, the receiving process of the mobile terminal 202 is performed as follows. The wireless signal from the base station 213 is received through the antennas 307-1 to 307-4. 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. In the demodulation unit 308, waiting calculation and multiplication processing can be performed. The demodulated data is transmitted to the decoding unit 309, and decoding processing such as error correction is performed. The decoded data is transmitted to the protocol processing unit 301, and protocol processing such as MAC, RLC, PDCP, SDAP, etc., such as removal of headers in each protocol, etc., is performed. Among the decoded data, the control data is transmitted to the control unit 310, and the user data is transmitted to the application unit 302.

[0078] A series of processes of the mobile terminal 202 are controlled by the control unit 310. Figure 4 Although omitted in FIG. 3 , the control unit 310 is also connected to each unit 302 and 304 to 309 .

[0079] Each part of the mobile terminal 202, such as the control unit 310, the protocol processing unit 301, the encoding unit 304, and the decoding unit 309, is implemented by a processing circuit including a processor and a memory. For example, the control unit 310 is implemented by the processor executing a program that describes a series of processes of the mobile terminal 202. The program that describes a series of processes of the mobile terminal 202 is stored in the memory. Examples of memories are non-volatile or volatile semiconductor memories such as RAM (Random Access Memory), ROM (Read Only Memory), and flash memory. Each part of the mobile terminal 202, such as the control unit 310, the protocol processing unit 301, the encoding unit 304, and the decoding unit 309 can be implemented by a dedicated processing circuit such as FPGA (Field Programmable Gate Array), ASIC (Application Specific Integrated Circuit), DSP (Digital Signal Processor). In Figure 4 In the present invention, the number of antennas used by the mobile terminal 202 for sending may be the same as or different from the number of antennas used for receiving.

[0080] Figure 5 Yes means Figure 2 The structure of the base station 213 is shown in FIG. Figure 5 The sending process of the base station 213 shown is explained. The EPC communication unit 401 sends and receives data between the base station 213 and the EPC. The 5GC communication unit 412 sends and receives data between the base station 213 and the 5GC (5GC unit 214, etc.). The other base station communication units 402 send and receive data with other base stations. The EPC communication unit 401, the 5GC communication unit 412, and the other base station communication units 402 exchange information with the protocol processing unit 403 respectively. The control data from the control unit 411, and the user data and control data from the EPC communication unit 401, the 5GC communication unit 412, and the other base station communication units 402 are sent to the protocol processing unit 403. Buffering of control data and user data can be performed. The buffering of control data and user data can be set in the control unit 411, can be set in the EPC communication unit 401, can be set in the 5GC communication unit 412, and can also be set in the other base station communication units 402.

[0081] The protocol processing unit 403 performs protocol processing such as SDAP, PDCP, RLC, and MAC, for example, performs routing of transmission data in DC, assigning headers in each protocol, and other actions. The data that has undergone protocol processing is transmitted to the encoding unit 405, and encoding processing such as error correction processing is performed. There may also be data that is directly output from the protocol processing unit 403 to the modulation unit 406 without performing encoding processing. In addition, data can be sent from the protocol processing unit 403 to other base station communication units 402. For example, in DC, data sent from the 5GC communication unit 412 or the EPC communication unit 401 can be sent to other base stations, such as auxiliary base stations, via other base station communication units 402. The encoded data is modulated in the modulation unit 406. Precoding in MIMO can also be performed in the modulation unit 406. After the modulated data is converted into a baseband signal, it is output to the frequency conversion unit 407 and converted into a wireless transmission frequency. Thereafter, the transmission signal is sent to one or more mobile terminals 202 using antennas 408-1 to 408-4. In Figure 5 , the example shows a case where the number of antennas is 4, but the number of antennas is not limited to 4.

[0082] In addition, the receiving process of the base station 213 is performed as follows. The wireless signal from one or more mobile terminals 202 is received by the antennas 408-1 to 408-4. The received signal is converted from the wireless receiving frequency to a baseband signal by the frequency conversion unit 407, and demodulated in the demodulation unit 409. The demodulated data is transmitted to the decoder unit 410 for decoding processing such as error correction. The decoded data is transmitted to the protocol processing unit 403, and protocol processing such as MAC, RLC, PDCP, SDAP, etc., such as the removal of headers in each protocol, is performed. Among the data after the protocol processing, the control data is transmitted to the control unit 411 or the 5GC communication unit 412 or the EPC communication unit 401 or other base station communication units 402, and the user data is transmitted to the 5GC communication unit 412 or the EPC communication unit 401 or other base station communication units 402. Data sent from other base station communication units 402 can be sent to the 5GC communication unit 412 or the EPC communication unit 401. The data may be, for example, uplink data sent to the 5GC communication unit 412 or the EPC communication unit 401 via other base stations in DC.

[0083] A series of processing of the base station 213 is controlled by the control unit 411. Figure 5 Although omitted in the figure, the control unit 411 is also connected to each of the parts 401, 402, 405 to 410, and 412.

[0084] Each part of the base station 213, such as the control unit 411, the protocol processing unit 403, the 5GC communication unit 412, the EPC communication unit 401, the other base station communication unit 402, the encoding unit 405, and the decoding unit 410 are implemented by a processing circuit including a processor and a memory, or a dedicated processing circuit such as an FPGA, an ASIC, or a DSP, similar to the mobile terminal 202. Figure 5 In the present invention, the number of antennas used by the base station 213 for sending may be the same as or different from the number of antennas used for receiving.

[0085] As Figure 2 The example of the structure of CU 215 is shown, except that Figure 5 In addition to the coding unit 405, modulation unit 406, frequency conversion unit 407, antennas 408-1 to 408-4, demodulation unit 409, and decoding unit 410 shown, a configuration with a DU communication unit may be used. The DU communication unit is connected to the protocol processing unit 403. The protocol processing unit 403 in the CU 215 performs protocol processing such as PDC and SDAP.

[0086] As Figure 2 The example of the structure of DU 216 is shown, except Figure 5 In addition to the EPC communication unit 401, other base station communication unit 402, and 5GC communication unit 412 shown, a configuration with a CU communication unit is sometimes used. The CU communication unit is connected to the protocol processing unit 403. The protocol processing unit 403 in the DU 216 performs protocol processing such as PHY, MAC, and RLC.

[0087] Figure 6 It is a block diagram showing the structure of the 5GC unit. Figure 6 The above Figure 2 The structure of the 5GC unit 214 is shown. Figure 6 Shown in Figure 2 The 5GC unit 214 shown includes the structure of AMF, the structure of SMF, and the structure of UPF. Figure 6In the example shown, the AMF may have the function of a control layer control unit 525, the SMF may have the function of a session management unit 527, and the UPF may have the functions of a user layer communication unit 523 and a data network communication unit 521. The data network communication unit 521 performs data transmission and reception between the 5GC unit 214 and the data network. The base station communication unit 522 performs data transmission and reception between the 5GC unit 214 and the base station 21 via the NG interface. The user data sent from the data network is transmitted from the data network communication unit 521 to the base station communication unit 522 via the user layer communication unit 523, and is sent to one or more base stations 213. The user data sent from the base station 213 is transmitted from the base station communication unit 522 to the data network communication unit 521 via the user layer communication unit 523, and is sent to the data network.

[0088] The control data transmitted from the base station 21 is transmitted from the base station communication unit 522 to the control layer control unit 525. The control layer control unit 525 may transmit the control data to the session management unit 527. The control data may be transmitted from the data network. The control data transmitted from the data network may be transmitted from the data network communication unit 521 to the session management unit 527 via the user layer communication unit 523. The session management unit 527 may transmit the control data to the control layer control unit 525.

[0089] The user plane control unit 523 includes a PDU processing unit 523-1, a mobile anchor unit 523-2, etc., and performs overall processing for the user plane (hereinafter sometimes referred to as U-Plane). The PDU processing unit 523-1 processes data packets, such as the transmission and reception of packets between the data network communication unit 521 and the transmission and reception of packets between the base station communication unit 522. The mobile anchor unit 523-2 is responsible for the connection of the data path when the UE moves.

[0090] The session management unit 527 manages the PDU session set between the UE and the UPF. The session management unit 527 includes a PDU session control unit 527-1, a UE IP address allocation unit 527-2, etc. The PDU session control unit 527-1 manages the PDU session between the mobile terminal 202 and the 5GC unit 214. The UE IP address allocation unit 527-2 allocates an IP address to the mobile terminal 202, etc.

[0091] The control layer control unit 525 includes a NAS security unit 525-1, an idle state mobility management unit 525-2, etc., and performs overall processing for the control layer (hereinafter, sometimes also referred to as C-Plane). The NAS security unit 525-1 performs security protection for NAS (Non-Access Stratum) messages, etc. The idle state mobility management unit 525-2 performs mobility management in the idle state (idle state: RRC_IDLE state, or simply called idle), generation and control of paging signals in the idle state, addition, deletion, update, retrieval, and tracking area list management of one or more mobile terminals 202 under coverage, etc.

[0092] A series of processing of the 5GC unit 214 is controlled by the control unit 526. Figure 6 Although omitted in the figure, the control unit 526 is connected to each unit 521 to 523, 525, and 527. Each part of the 5GC unit 214 is similar to the control unit 310 of the mobile terminal 202, and is implemented by, for example, a processing circuit including a processor and a memory, or a dedicated processing circuit such as an FPGA, ASIC, or DSP.

[0093] Next, an example of a cell search method in a communication system is shown. Figure 7 This is a flowchart showing an overview of the cell search and standby operation performed by a communication terminal (UE) in a communication system of the NR mode. If the communication terminal starts the cell search, in step ST601, the first synchronization signal (P-SS) and the second synchronization signal (S-SS) sent from the surrounding base stations are used to synchronize the time slot timing and the frame timing.

[0094] P-SS and S-SS are collectively referred to as synchronization signals (SS). The synchronization signal (SS) is assigned a synchronization code that corresponds to the PCI (Physical Cell Identifier) ​​assigned to each cell. The number of PCIs is set to 1008. The communication terminal uses the 1008 PCIs to achieve synchronization and detects (determines) the PCI of the synchronized cell.

[0095] In step ST602, the communication terminal receives the PBCH for the next cell to acquire synchronization. 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, SFN (System Frame Number), scheduling information of SIB (System Information Block) 1, subcarrier spacing of SIB1, etc., information on DM-RS positions, etc.

[0096] In addition, the communication terminal obtains the SS block identifier through the PBCH. A portion of the bit column of the SS block identifier is included in the MIB. The remaining bit column is included in the identifier of the sequence used to generate the DM-RS attached to the PBCH. The communication terminal uses the MIB included in the PBCH and the sequence of the DM-RS attached to the PBCH to obtain the SS block identifier.

[0097] Next, in step ST603, the communication terminal measures the reception power of the SS block.

[0098] Next, in step ST604, the communication terminal selects a cell with the best reception quality from the one or more cells detected up to step ST603, for example, a cell with the highest reception power, i.e., the best cell. In addition, the communication terminal selects a beam with the best reception quality, for example, a beam with the highest reception power of an SS block, i.e., the best beam. The best beam is selected, for example, using the reception power of the SS block identified by each SS block.

[0099] Next, in step ST605, the communication terminal receives DL-SCH based on the scheduling information of SIB1 included in the MIB, and obtains SIB (System Information Block) 1 in the broadcast information BCCH. SIB1 includes information related to access to the cell, cell structure information, and scheduling information of other SIBs (SIBk: an integer of k ≥ 2). In addition, SIB1 also includes a tracking area code (Tracking Area Code: TAC).

[0100] 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 already held by the communication terminal. The tracking area list is also called the TAI list (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.

[0101] If the result of the comparison in step ST606 is that the TAC received in step ST605 is the same as the TAC included in the tracking area list, the communication terminal enters the standby action in the cell. If the TAC received in step ST605 is not included in the tracking area list, the communication terminal passes through the cell and requests the core network (CoreNetwork, EPC) including MME, etc. to change the tracking area to perform TAU (Tracking Area Update).

[0102] 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.

[0103] Next, an example of a random access method in a communication system is shown. In random access, 4-step random access and 2-step random access are used. In addition, for 4-step random access and 2-step random access, there are contention-based random access, that is, random access that may cause timing contention with other mobile terminals, and contention-free random access.

[0104] An example of a contention-based 4-step random access method is shown. As step 1, the mobile terminal sends a random access preamble to the base station. The random access preamble may be selected by the mobile terminal from a predetermined range, or may be individually allocated to the mobile terminal and notified by the base station.

[0105] As step 2, the base station sends a random access response to the mobile terminal. The random access response includes the uplink scheduling information used in step 3, the terminal identity used in the uplink transmission in step 3, and the like.

[0106] As step 3, the mobile terminal performs uplink transmission to the base station. The mobile terminal uses the information obtained in step 2 in uplink transmission. As step 4, the base station notifies the mobile terminal whether there is contention resolution. The mobile terminal notified of no conflict ends the random access process. The mobile terminal notified of a conflict starts the process again from step 1.

[0107] The contention-free 4-step random access method is different from the contention-based 4-step random access method in the following points: That is, the base station pre-allocates a random access preamble and uplink scheduling to the mobile terminal before step 1. In addition, the notification of whether or not a contention is resolved in step 4 is not required.

[0108] An example of a conflict-based 2-step random access method is shown. As step 1, the mobile terminal transmits a random access preamble and an uplink transmission to the base station. As step 2, the base station notifies the mobile terminal whether there is a conflict. The mobile terminal notified of no conflict ends the random access process. The mobile terminal notified of a conflict starts the process again from step 1.

[0109] The contention-free 2-step random access method is different from the contention-based 2-step random access method in the following respects: That is, before step 1, the base station pre-allocates a random access preamble and uplink scheduling to the mobile terminal. In addition, in step 2, the base station sends a random access response to the mobile terminal.

[0110] Figure 8 This shows an example of the structure of a cell in NR. In a cell in NR, a narrow beam is formed and its direction is changed for transmission. Figure 8 In the example shown, the base station 750 uses beam 751-1 at a certain time to transmit and receive with the mobile terminal. At other times, the base station 750 uses beam 751-2 to transmit and receive with the mobile terminal. Similarly, the base station 750 uses one or more of beams 751-3 to 751-8 to transmit and receive with the mobile terminal. Thus, the base station 750 forms a wide range of cells 752.

[0111] exist Figure 8 In FIG. 1 , an example is shown in which the number of beams used by the base station 750 is set to 8, but the number of beams may be different from 8. Figure 8 In the example shown, the number of beams used simultaneously by the base station 750 is set to one, but it may be multiple.

[0112] The identification of beams uses the concept of QCL (Quasi-CoLocation) (refer to non-patent document 14 (3GPP TS 38.214)). That is, the beam is identified by information indicating which reference signal (e.g., SS block, CSI-RS) the beam can be considered to be the same as. This information sometimes includes the type of information about the viewpoints that can be considered to be the same beam, such as information about Doppler shift, Doppler shift spread, average delay, average delay spread, and spatial Rx parameters (refer to non-patent document 14 (3GPP TS38.214)).

[0113] In 3GPP, D2D (Device to Device) communication and V2V (Vehicle to Vehicle) communication support side links (SL) (see Non-Patent Documents 1 and 16). SL is defined by the PC5 interface.

[0114] In SL communication, in addition to broadcast, in order to support unicast and groupcast, the support of PC5-S signaling is studied (refer to non-patent document 27 (3GPP TS 23.287)). For example, PC5-S signaling is implemented to establish SL, that is, a link for implementing PC5 communication. This link is implemented in the V2X layer and is also called a layer 2 link.

[0115] In addition, in SL communication, support for RRC signaling is being studied (see non-patent document 27 (3GPP TS23.287)). RRC signaling in SL communication is also called PC5 RRC signaling. For example, it is proposed to notify the capabilities of UEs between UEs performing PC5 communication, or to notify the settings of the AS layer for V2X communication using PC5 communication.

[0116] Fig. 9 An example of the connection structure of a mobile terminal in SL communication is shown in FIG. Fig. 9 In the example shown, UE 805 and UE 806 exist within the coverage area 803 of base station 801. UL / DL communication 807 is performed between base station 801 and UE 805. UL / DL communication 808 is performed between base station 801 and UE 806. SL communication 810 is performed between UE 805 and UE 806. UE 811 and UE 812 exist outside the coverage area 803. SL communication 814 is performed between UE 805 and UE 811. In addition, SL communication 816 is performed between UE 811 and UE 812.

[0117] As an example of communication between UE and NW via relay in SL communication, Fig. 9 UE 805 is shown relaying communications between UE 811 and base station 801 .

[0118] A UE that performs relaying sometimes uses Figure 4 Same structure. Use Figure 4 The relay processing in the UE is described. The relay processing of UE 805 in the communication from UE 811 to base station 801 is described. The wireless signal from UE 811 is received through antennas 307-1 to 307-4. The received signal is converted from the wireless reception frequency to a baseband signal by the frequency conversion unit 306, and demodulated in the demodulation unit 308. In the demodulation unit 308, waiting calculation and multiplication processing can be performed. The demodulated data is transmitted to the decoding unit 309, and decoding processing such as error correction is performed. The decoded data is transmitted to the protocol processing unit 301, and protocol processing such as MAC, RLC, etc. for communication with UE 811, such as removal of headers in each protocol, etc. is performed. In addition, protocol processing such as RLC, MAC, etc. for communication with base station 801, such as the addition of headers in each protocol, etc. is performed. In the protocol processing unit 301 of UE 811, protocol processing of PDCP and SDAP is sometimes performed. The data that has been processed by the protocol is transmitted to the coding unit 304, and coding processing such as error correction processing is performed. There may also be data that is directly output from the protocol processing unit 301 to the modulation unit 305 without being subjected to coding processing. The data that has been coded by the coding unit 304 is modulated in the modulation unit 305. Precoding in MIMO may also be performed in the modulation unit 305. After the modulated data is converted into a baseband signal, it is output to the frequency conversion unit 306 and converted into a wireless transmission frequency. Thereafter, the transmission signal is transmitted from the antennas 307-1 to 307-4 to the base station 801.

[0119] In the above content, an example of relaying of UE 805 in communication from UE 811 to base station 801 is shown, but the same processing is also used in relaying of communication from base station 801 to UE 811.

[0120] 5G base stations can support integrated access and backhaul (IAB) (see non-patent literature 2, 20). A base station that supports IAB (hereinafter sometimes referred to as an IAB base station) is composed of a CU of a base station that acts as an IAB host providing IAB functions, namely, an IAB host CU, a DU of a base station that acts as an IAB host, namely, an IAB host DU, and an IAB node that uses a wireless interface to connect to the IAB host DU and to the UE. An F1 interface is set between the IAB node and the IAB host CU (see non-patent literature 2).

[0121] Fig.10 An example of the connection of an IAB base station is shown in FIG. An IAB host CU 901 is connected to an IAB host DU 902. An IAB node 903 is connected to an IAB host DU 902 using a wireless interface. An IAB node 903 is connected to an IAB node 904 using a wireless interface. That is, multi-level connections of IAB nodes are sometimes made. A UE 905 is connected to an IAB node 904 using a wireless interface. A UE 906 is sometimes connected to an IAB node 903 using a wireless interface, and a UE 907 is sometimes connected to an IAB host 902 using a wireless interface. Multiple IAB host DUs 902 can be connected to an IAB host CU 901, multiple IAB nodes 903 can be connected to an IAB host DU 902, and multiple IAB nodes 904 can be connected to an IAB node 903.

[0122] In the connection between the IAB host DU and the IAB node and the connection between the IAB nodes, a BAP (Backhaul Adaptation Protocol) layer is set (see non-patent document 29). The BAP layer performs operations such as routing received data to the IAB host DU and / or IAB node, mapping to the RLC channel, etc. (see non-patent document 29).

[0123] As the structure of the IAB host CU, the same structure as that of the CU 215 is used.

[0124] The structure of the IAB host DU is the same as that of the DU 216. The protocol processing unit of the IAB host DU performs BAP layer processing, such as adding a BAP header to downlink data, routing to an IAB node, and removing a BAP header from uplink data.

[0125] As an example of the structure of an IAB node, sometimes in addition to Figure 5 The structure other than the EPC communication unit 401, other base station communication unit 402, and 5GC communication unit 412 shown.

[0126] use Figure 5 , Fig.10 To illustrate the transceiver processing in the IAB node. The transceiver processing of the IAB node 903 in the communication between the IAB host CU 901 and the UE 905 is explained. In the uplink communication from the UE 905 to the IAB host CU 901, the wireless signal from the IAB node 904 is received through the antenna 408 (part or all of the antennas 408-1 to 408-4). The received signal is converted from the wireless reception frequency to a baseband signal by the frequency conversion unit 407, and demodulated in the demodulation unit 409. The demodulated data is transmitted to the decoding unit 410, and decoding processing such as error correction is performed. The decoded data is transmitted to the protocol processing unit 403, and protocol processing such as MAC, RLC, etc. for communication with the IAB node 904, such as removal of headers in each protocol, etc., is performed. In addition, routing to the IAB host DU 902 using the BAP header is performed, and protocol processing such as RLC, MAC, etc. for communication with the IAB host DU 902, such as the assignment of headers in each protocol, is performed. The data that has undergone protocol processing is transmitted to the encoding unit 405, and encoding processing such as error correction processing is performed. There may also be data that is directly output from the protocol processing unit 403 to the modulation unit 406 without performing encoding processing. The encoded data is modulated in the modulation unit 406. Precoding in MIMO may also be performed in the modulation unit 406. After the modulated data is converted into a baseband signal, it is output to the frequency conversion unit 407 and converted into a wireless transmission frequency. Thereafter, the transmission signal is sent to the IAB host DU 902 using antennas 408-1 to 408-4. The same processing is also performed in the downlink communication from the IAB host CU 901 to the UE 905.

[0127] The IAB node 904 also performs the same transmission and reception processing as the IAB node 903. In the protocol processing unit 403 of the IAB node 903, as BAP layer processing, for example, the addition of a BAP header in uplink communication and routing to the IAB node 904, and the removal of a BAP header in downlink communication are performed.

[0128] In 5G wireless access systems, achieving communications suitable for XR and cloud gaming services has become an important issue. The characteristics of XR traffic in 3GPP have been studied (see non-patent document 34). As characteristics of XR traffic, for example, non-integer periodicity, data generation time variation (jitter) characteristics, data volume variation characteristics, low latency characteristics, etc. can be cited. In order to achieve communications suitable for XR or cloud gaming services, a communication method that takes into account the characteristics of such XR traffic is required.

[0129] If the XR service communicates in the UL, since the UL data of the XR traffic is generated at the UE, the NW will not be able to identify the characteristics of the UL XR traffic generated at the UE. For example, the NW cannot identify the generation timing, data volume, etc. of the UL data. In addition, even if the QoS of the UL XR traffic is set as an XR service at the NW, the NW cannot identify the performance of the UL XR traffic actually sent from the UE. Since the NW cannot identify the characteristics of the UL XR traffic, the following problems sometimes occur: scheduling or modification suitable for the UL XR traffic cannot be performed, and the communication quality is reduced.

[0130] This first embodiment discloses a method for solving such a problem.

[0131] In this method, the UE sends information about UL data to the gNB. 8 examples of information related to UL data are disclosed. (1) Data generation cycle. (2) Data jitter occurs. (3)Frame rate. (4)Data rate. (5)Data volume. (6) Packet delay budget. (7) Number of flows. (8) A combination of (1) to (7).

[0132] UL data may be data to be sent instead of generated data. For example, data transmission timing may be used instead of data generation timing. For example, data transmission period may be used instead of data generation period, and data transmission jitter may be used instead of data generation jitter. Thus, information about the data actually sent may be obtained.

[0133] The information related to the UL data generated at the UE may be each application data. The information related to the UL data generated at the UE may also be each group of data. A group of data may also be a PDU set. The information related to the UL data generated at the UE may also be each PDU set. The information related to the UL data generated at the UE may be each PDU set corresponding to the application data. For example, it may also be the generation period of the application data or the data amount of the application data. Thus, the gNB can obtain the information related to the UL data of each application data. The gNB can set the CG suitable for the application to be communicated.

[0134] The information related to the UL data generated at the UE may be statistical data. In this case, the UE obtains statistical data of the information related to the UL data. The UE may use the obtained statistical data as information related to the UL data. As statistical data, there are average values, central values, standard deviations, variances, cutoff ranges, maximum values, minimum values, first quartiles, third quartiles, mode values, number of data, and the like. The statistical data acquisition period may be statically determined in advance by standards, etc. For example, it may be set from the start of data communication to the time when the information is sent from the UE to the gNB. As another method, the NW may notify the UE of the setting information of the period to be acquired. The gNB may notify the UE of the period setting information, etc. The statistical data is acquired according to the period setting information received by the UE from the NW. The NW is capable of setting the acquisition period according to, for example, the service status. The gNB is capable of acquiring statistical data of the information related to the UL data from the UE. By using the information related to the UL data as statistical data, it is possible to acquire information related to a lot of UL data, information related to the UL data over a long period of time, and the like. For each piece of information related to the UL data, information taking into account deviations may be acquired.

[0135] The information related to the UL data generated at the UE may also be statistical data of each application data. The above methods may be appropriately combined. For each application data, the same effect may be obtained.

[0136] The UE can notify the gNB of the preference information related to the CG setting. The preference information related to the CG setting includes CG period, offset, time domain resource allocation, frequency domain resource allocation, etc. It can also be a combination of them. The gNB receives the preference information related to the CG setting from the UE so that the UE can identify the preferred CG setting.

[0137] Information related to UL data and preference information related to CG settings can be per stream. For example, it can be per stream of XR traffic. The gNB can obtain information for each stream. This information can be per QoS stream. The gNB can obtain information for each stream. This information can also be information for each bearer. The gNB can obtain information for each bearer.

[0138] The gNB can use the information related to UL data and the preference information related to CG settings obtained from the UE to set a CG suitable for communication. This enables scheduling of XR traffic suitable for UL, improving low-latency characteristics and improving communication quality.

[0139] A method for sending information related to UL data and preference information related to CG settings from a UE to a gNB is disclosed. The information can be sent using RRC signaling. A new message can be set up to send this information. By distinguishing it from other information, false operations can be reduced. Alternatively, an existing message can be used to send this information. For example, a UE assistance information message can be used. Complicated processing can be avoided. By using RRC signaling, the amount of information can be increased. In addition, the transmission reachability from the UE to the gNB can be improved. False operations can be reduced.

[0140] Other methods for sending this information are disclosed. MAC signaling may also be used. It may be included in a MAC CE for sending. A new MAC CE may be set up for sending this information. By distinguishing it from other information, erroneous operations may be reduced. This information may be sent using an existing MAC CE. Complexity of processing may be avoided. By using MAC signaling, for example, a PUSCH set by the CG may be used to send from the UE to the gNB. An effort is made to simplify the sending process.

[0141] Other methods for sending this information are disclosed. PUCCH can be used. It can be included in UCI for sending. A new UCI can be set up for sending this information. By distinguishing it from other information, false operations can be reduced. This information can be sent using existing UCI. It can avoid processing complications. By using PUCCH, it can be sent dynamically earlier.

[0142] This information can be sent from the UE to the gNB periodically or regularly. The gNB can periodically or regularly receive information related to the UL data at the UE and information related to the setting of the CG, and can identify the situation. As another method, this information can be sent from the UE to the gNB by triggering. The UE can set the conditions for sending this information to the gNB. The conditions can be sent from the gNB to the UE in advance. For example, the standard deviation of the jitter exceeds 3ms, the change in the average value is more than 1ms higher than the previous report, etc. The gNB can send the conditions required to determine whether a scheduling change is required to the UE. As a result, the gNB can obtain this information at the timing when it is needed.

[0143] As another method, this information can be sent from the UE to the gNB by triggering. The UE can set the conditions for sending this information. The UE can set the conditions for the gNB to determine whether a scheduling change is required. Thus, the gNB can obtain this information at the timing when the conditions set by the UE occur.

[0144] As another method, this information can be sent from the UE to the gNB by triggering. The application can set the conditions for sending this information. The application can set the conditions required for the gNB to determine whether a scheduling change is required. The application can send the condition to the UE, or the application server (AS) or application function (AF) can send the condition to the UE. In addition, the condition can be sent from the application to the gNB, or the AS or AF can send the condition to the gNB. As a result, the gNB can obtain this information at the timing when the condition set by the application occurs in the UE.

[0145] The gNB can request the UE to send information related to UL data. The gNB can also request the UE to send preference information related to CG settings. The UE receives a request to send the information from the gNB. The UE can send the information to the gNB upon receiving the request to send the information from the gNB. The method for sending the information when the UE receives the request to send the information from the gNB can be the method disclosed above. Information indicating which of the above-disclosed methods for sending the information is used can be sent from the gNB to the UE. It can be sent together with the request to send the information. The UE can set the sending method based on the information received from the gNB indicating which method to use. As a result, the gNB can flexibly set the sending method for the UE and can request the UE to send the information.

[0146] The UE may send the information to the gNB upon receiving a request to send the information from the gNB. For example, when a need arises in the gNB to change the scheduling of UL data, a request to send the information is sent to the UE. The UE sends the information to the gNB based on the request to send the information received from the gNB. Thus, the gNB can cause the UE to send the information at the necessary timing.

[0147] A method for sending a request for sending the information from the gNB to the UE is disclosed. RRC signaling may be used. A new message for sending a request for sending the information may be set. By distinguishing it from other information, erroneous operations may be reduced. An existing message may be used to send a request for sending the information. For example, an RRC reconfiguration message may be used. Complicated processing may be avoided. By using RRC signaling, the amount of information may be increased. For example, it may be sent together with the CG setting. For example, it may be sent before data communication starts. Statistics on information related to UL data may be obtained as early as possible in the UE.

[0148] Other methods of sending the request to send the public information. MAC signaling can also be used. It can be included in the MAC CE for sending. A new MAC CE can be set up to send the request to send the information. By distinguishing it from other information, false operations can be reduced. The existing MAC CE can be used to send the request to send the information. The complexity of the processing can be avoided. By using MAC signaling, it can be sent as early as possible, and false operations can be reduced through HARQ processing.

[0149] Other methods for sending this information are disclosed. PUCCH can be used. It can be included in DCI for transmission. A new DOC can be set up for sending this information. By distinguishing it from other information, false operations can be reduced. This information can be sent using existing DCI. For example, it can be included in the DCI for activating / deactivating CG for transmission. It can avoid complication of processing. By using PDCCH, it can be sent dynamically earlier.

[0150] Fig.11 It is a diagram showing a flow example of a method for sending information related to UL data and preference information related to CG settings from UE to gNB. Between the gNB and the UE, each process in steps ST3901 to ST3905 included in step ST3901 is performed, and information related to UL data and preference information related to CG settings are sent from the UE to the gNB. That is, in step ST3901, the gNB sends a request to send information related to UL data and preference information related to CG settings to the UE. It is sent using an RRC reconfiguration message. As a result, the UE performs settings for acquiring information related to UL data and settings for deriving preference information related to CG settings. In step ST3902, the UE sends an RRC reconfiguration complete message to the gNB. A completion notification of the settings requested in step ST3901 can be sent. In step ST3903, data communication is performed between the UE and the gNB. In step ST3904, the UE acquires information related to UL data in the data communication and derives preference information related to CG settings. In step ST3905, the UE sends information related to the acquired and exported UL data and preference information related to the CG setting to the gNB periodically, periodically, or triggered. For example, in step ST3901, it can be set from the gNB whether it is periodic, periodic, or triggered, and the UE can send it according to the setting method. Fig.11In the RRC signaling, this information is sent using UE assistance information (AssistanceInformation). As a result, the gNB can obtain information related to UL data and preference information related to CG settings from the UE. The gNB can use the information related to UL data and preference information related to CG settings obtained from the UE to set a CG suitable for communication. As a result, the low latency characteristics and communication quality can be improved.

[0151] exist Fig.11 In the figure, a case is shown where both information related to UL data and preference information related to CG settings are sent, but only one of them may be sent.

[0152] A method for sending information related to UL data and preference information related to CG settings from UE to gNB is disclosed. The information can be sent from the UE to the CN (Core Network). Alternatively, the information obtained from the UE can be sent from the gNB to the CN. As a function of the CN, for example, it can be AMF. NAS signaling can be used to send information related to UL data and preference information related to CG settings from the UE to the AMF. As a result, the information related to UL data and the preference information related to CG settings can be used in the functions of the CN or the nodes of the CN.

[0153] A CN function or a CN node that receives information related to UL data and preference information related to CG settings from a UE or a gNB can notify the NWDAF (Network Data Analytic function) of the information. The NWDAF can use the information. The NWDAF can use the acquired information related to UL data and preference information related to CG settings, for example, to perform communication control or NW operations. As a result, communication control or NW operations suitable for XR traffic of UL can be performed, thereby improving low-latency characteristics and communication quality.

[0154] NWDAF can send the analysis result derived using the information related to UL data and the preference information related to CG settings received from the UE or from the gNB to the application. The application can request the analysis result from NWDAF. NWDAF can send the analysis result to the application based on the request. Although the transmission and reception between NWDAF and the application is disclosed, the analysis result or the request can also be transmitted and received between NWDAF and an application server (AS) or an application function (AF). The application can transmit and receive the analysis result or the request to and from NWDAF via the AF or AS. Thus, the analysis result can be used in the application.

[0155] The function of the CN or the node of the CN that receives the information related to the UL data and the preference information related to the CG setting from the UE can notify the gNB of the information. The gNB can use the information. As disclosed above, the gNB can use the information related to the UL data and the preference information related to the CG setting obtained from the UE to perform CG settings suitable for communication. Thereby, it is possible to schedule XR traffic suitable for UL, achieve improved low latency characteristics and improved communication quality.

[0156] In addition, the information can be sent from the UE to the application function (AF) or the application server (AS). The information obtained from the UE can also be sent from the gNB to the AF or AS. The gNB can send the information to the AF or AS via the CN. Thus, the information related to the UL data and the preference information related to the CG setting can be used by the AF or AS or the application.

[0157] A method for sending a request for sending the information from the gNB to the UE is disclosed. The CN may send a request for sending the information to the UE. Alternatively, the CN may send a request for sending the information to the gNB. The gNB that receives the request may also send the information to the UE. Thus, the function of the CN or the node of the CN can send a request for sending information related to UL data and preference information related to CG settings.

[0158] In addition, a request for sending the information can also be sent from the AF or AS to the UE. The AF or AS can send a request for sending the information to the gNB. The AF or AS can send a request for sending the information to the gNB via the CN. The gNB that receives the request can also make a request for sending the information to the UE. Thus, the AF or AS or application can make a request for sending information related to UL data and preference information related to CG settings.

[0159] DL is made public. The gNB can send information related to DL data and preference information related to the setting of SPS (SemiPersistent Schedul ing) to the CN or AF or AS. In addition, the CN or AF or AS can send a request to the gNB to send information related to DL data and preference information related to the setting of SPS. Thus, the AF or AS or application can make a request to send information related to UL data and preference information related to the setting of CG. Thus, the CN or CN node, or the AF or AS or application can obtain information related to DL data and preference information related to the setting of SPS. In addition, the CN or CN node, or the AF or AS or application can make a request to send information related to DL data and preference information related to the setting of SPS.

[0160] Fig.121 is a diagram showing an example of a flow chart of a method for transmitting information related to UL data and DL data from a gNB to an AF. Fig.12 In the process, UL data and DL data are included and recorded as XR data. In step ST4001, data is sent and received between AF, UPF, gNB, and UE. In steps ST4002 to ST4005, AF sends a request for sending information related to XR data (XR data association information request) to gNB via NEF (Network Exposure Function), PCF, AMF / SMF. The gNB that receives the request for sending this information obtains the information related to DL data in step ST4006. In addition, the gNB that receives the request for sending this information sends a request to the UE. Fig.11 The processing of step ST3910 described above obtains information related to UL data from UE. In steps ST4007 to ST4010, the gNB that has obtained information related to DL data and information related to UL data sends information related to XR data to AF via AMF / SMF, PCF, and NEF. As a result, AF can obtain information related to XR data from gNB and UE.

[0161] exist Fig.12 In the disclosure, the case of sending both DL data and UL data is disclosed, but only one of them may be sent. Fig.12 Although the case of sending information related to XR data is disclosed in , preference information related to the settings of CG and / or SPS may also be sent. The same method may be appropriately applied.

[0162] Thus, the CN function or the CN node, or the AF or AS or the application can obtain information related to DL data, information related to UL data, preference information related to the SPS setting, preference information related to the CG setting, and information combining them.

[0163] The CN function or the CN node uses the acquired information to implement the QoS or QoS flow modification required by the service, flow modification, modification of resource settings for communication, such as modification of network slice settings or modification of UPF used, etc. As a result, communication suitable for XR traffic can be carried out, thereby improving communication quality.

[0164] In addition, the AF, AS, or application can use the acquired information to modify the QoS requested for the service, etc. This makes it possible to provide a service suitable for XR traffic.

[0165] Implementation method 2. A combination of multiple data (hereinafter sometimes referred to as a PDU set) can be set. The data of the PDU set can be discarded when the communication failure of a part of the data in the PDU set is used as an opportunity. The discarding can also be performed in the base station. The base station can discard the data of the PDU set before sending.

[0166] However, even when the data of the PDU set is discarded in the base station, the data of the PDU set received in the UE is not discarded but remains, thereby causing a problem that the data is retained in the UE.

[0167] This embodiment 2 discloses a method for solving the above-mentioned problem.

[0168] In this method, a function of discarding data is set in the UE. The UE can discard the data of the PDU set. The UE can discard the data of the PDU set that has been completely received.

[0169] Both the base station and the UE can have the function of discarding data. Both the base station and the UE can discard the data of the PDU set. The base station can discard the PDU data before sending. The UE can discard the PDU data after receiving it.

[0170] The identifier of the PDU set may be set. The identifier may be set for discarding data of the PDU set. The base station may notify the UE of information related to the discarded PDU set. The information may be, for example, the identifier of the discarded PDU set. The UE receives the identifier of the discarded PDU set from the base station. The UE may use the identifier to discard the PDU data.

[0171] The base station can use the RTP (Realtime Transport Protocol) header to notify the identifier. The RTP header can contain information that identifies the identifier of the PDU set. The UE can use the header to obtain information related to the PDU set to be discarded. The UE can perform the action of obtaining in the PDCP layer or the IP layer. For example, the PDCP layer of the UE can obtain the information from the RTP header contained in the PDCP SDU (Service Data Unit). The IP layer of the UE can obtain the information from the RTP header contained in the IP payload.

[0172] As another example, the base station may use a GTP (GPRS Tunnelling Protocol) header to notify the identifier. The GTP header may include information representing the identifier of the PDU set. The base station may notify the UE of relevant information of the RTP header corresponding to the GTP header, and may also notify the UE of relevant information of the PDCP SN corresponding to the GTP header. The information related to the RTP header may, for example, include information related to the beginning RTP data, may also include information related to the end RTP data, may also include information related to the range of the RTP data, and may also include information related to the number of RTP data. The information related to the PDCP SN (Sequence Number) may, for example, include information related to the beginning PDCP SN, may also include information related to the end PDCP SN, may also include information related to the range of the PDCP SN, and may also include information related to the number of PDCP SNs.

[0173] Other solutions are disclosed. A timer for discarding a PDU set is set. The base station notifies the UE of the timer. The UE starts the timer upon receiving the first packet in the PDU set. The UE stops the timer upon receiving all packets in the PDU set. The UE discards the data of the PDU set upon the expiration of the timer.

[0174] The UE may have this timer for each PDU set. Thus, for example, even in the case where data of a subsequent PDU set is received before a part of the data of a previous PDU set, control can be performed by the timer of the PDU set. As another example, the UE may have only one such timer. For example, in the case where the UE receives data of a subsequent PDU set before a part of the data of a previous PDU set, the UE may start the timer involving the subsequent PDU set when the timer involving the data of the previous PDU set stops or expires. Thus, for example, complexity associated with the control of the timer can be avoided.

[0175] The UE may share the timer between multiple PDCP entities. Thus, for example, the complexity of processing in the communication system can be avoided. As another example, the UE may share the timer between multiple RLC entities. Thus, for example, the same effect as above can be obtained.

[0176] The UE may discard the data involved in the PDU set retained in the L2 layer and / or the L1 layer when the timer expires. The L2 layer and / or the L1 layer may be, for example, SDAP, PDCP, RLC, MAC, PHY, or a plurality of the above. Thus, for example, the complexity of control in the communication system can be avoided.

[0177] Other solutions are disclosed. The base station notifies the UE of the packet delay budget of the PDU set. For example, the packet delay budget may be the packet delay budget involved in the downlink PDU set. The base station may use RRC signaling, such as RRC reconfiguration, to notify the UE of the notification.

[0178] As another example, the core NW device may notify the UE of the packet delay budget of the PDU set. The core NW device may be, for example, a PCF. For example, the PCF may notify the UE of the packet delay budget. For example, the PCF may notify the UE of the packet delay budget in the UE's registration process, may notify the UE of the packet delay budget in the PDU session establishment process, and may also notify the UE of the packet delay budget in the QoS policy setting (QoS Policy Configuration) process. The core NW device may be, for example, a UDM (Unified Data Management). For example, the UDM may notify the UE of the packet delay budget. For example, the UDM may notify the UE of the packet delay budget in the UE's registration process, may notify the UE of the packet delay budget in the PDU session establishment process, and may also notify the UE of the packet delay budget in the QoS policy setting process.

[0179] The UE may discard the data in the PDU set when the following situation is used as a trigger: all the data in the PDU set cannot be received within the packet delay budget from the reception of the first data in the PDU set.

[0180] The packet delay budget of the PDU set may be provided with an offset. For example, the time required for communication from the base station to the UE may be set to the offset. In the above processing of the UE, the packet delay budget may be replaced with a value obtained by adding the offset to the packet delay budget. Thus, for example, even when communication from the base station to the UE requires a long time, it is possible to prevent unnecessary data of the PDU set from being discarded.

[0181] The packet data may also be assigned a timestamp. The UE may use the timestamp to start the calculation of the packet delay budget. As another example, the UE may use the timestamp of the RTP to start the calculation of the packet delay budget. This, for example, can avoid the complexity associated with the control of the use of the packet delay budget in the UE. The above timestamp may be assigned only to the first packet of the PDU set. This, for example, can reduce the size of the packet.

[0182] The method used in this embodiment 2 can be used in uplink data. For example, the UE can discard the data of the PDU set that is being sent, and the base station can discard the data of the PDU set that is being received. The UE can notify the base station of information related to the PDU set. For example, the information can be an identifier of the PDU set, a timer involved in the PDU set, or a packet delay budget of the PDU set. As a result, for example, the same effect as the downlink can be obtained.

[0183] Whether to discard the data of the PDU set is configurable. The base station can notify the UE of information indicating whether to discard. The UE can use the information to discard the data of the PDU set, or not to discard the data of the PDU set. This can improve the flexibility of the communication system, for example.

[0184] The method used in this embodiment 2 can be used in uplink data. For example, the UE can discard the data of the PDU set that is being sent, and the base station can discard the data of the PDU set that is being received. The UE can notify the base station of information related to the PDU set. For example, the information can be an identifier of the PDU set, a timer involved in the PDU set, or a packet delay budget of the PDU set. As a result, for example, the same effect as the downlink can be obtained.

[0185] According to the second embodiment, it is possible to prevent the data of the PDU set in the UE from being retained, and as a result, it is possible to avoid the buffer overflow in the UE, thereby reducing the UE's malfunction. In addition, it is possible to reduce the buffering amount of the UE.

[0186] Implementation method 3. The UE may notify the base station of information related to discarded PDU sets. The information related to the PDU sets may include, for example, information related to the number of discarded PDU sets. The information related to the number may be, for example, the number of PDU sets discarded within a specified time, the number of discarded PDU sets within a specified number of PDU sets, the GOP (Group Of Picture) unit, each video frame, each video stream, or each QoS stream. Information related to the proportion of discarded PDU sets may be included.

[0187] As another example, the information related to the PDU set may include information related to discarded data. The information related to the amount of discarded data may be the amount of data in the PDU set, the proportion of discarded data, or the same information as the above-mentioned information related to the number of PDU sets.

[0188] As another example, the information related to the PDU set may be a statistical value.

[0189] The information on the PDU set may be information on the downlink, information on the uplink, or information on both the downlink and uplink.

[0190] The UE may obtain information related to the discarded PDU set. As another example, the information may be obtained by the base station. For example, the CU of the base station may obtain the information, the DU may also obtain the information, and the TRP may also obtain the information. As another example, the information may also be obtained by the core NW device.

[0191] The method in which the UE transmits information on discarded PDU sets to the base station may appropriately apply the method for transmitting information on UL data from the UE to the base station disclosed in Embodiment 1.

[0192] The base station can use the notified information to control the wireless network, for example, to allocate wireless resources to UE or control MCS (Modulation and Coding Scheme), or to control SPS and / or CG.

[0193] The base station may request the UE to send information related to the discarded PDU set. This method may appropriately apply the request method disclosed in Embodiment 1 for requesting information related to UL data from the UE to the base station.

[0194] A method for sending information related to discarded PDU sets from a UE to a gNB is disclosed. The information may be sent from the UE to the CN. Alternatively, the information obtained from the UE may be sent from the gNB to the CN. These methods may appropriately apply the method disclosed in Implementation 1 for sending information related to UL data from the UE to the CN or from the gNB to the CN.

[0195] A function of the CN or a node of the CN that receives information about a discarded PDU set from the UE or from the gNB may notify the NWDAF of the information. The NWDAF may use the information. The NWDAF may use the acquired information about the discarded PDU set to perform, for example, communication control or NW operations. For example, the notified information may be used for QoS control, or for priority control of the PDU set. As a result, for example, communication control or NW operations suitable for services such as XR may be performed, thereby improving low latency characteristics and communication quality.

[0196] NWDAF can send the analysis result derived using the information about the discarded PDU set received from the UE or from the gNB to the application. The application can request the analysis result from NWDAF. NWDAF can send the analysis result to the application based on the request. Although the transmission and reception between NWDAF and the application is disclosed, the analysis result or the request can also be transmitted and received between NWDAF and an application server (AS) or an application function (AF). The application can transmit and receive the analysis result or the request to and from NWDAF via the AF or AS. Thus, the analysis result can be used in the application.

[0197] A function of the CN or a node of the CN that receives information about discarded PDU sets from the UE may notify the gNB of the information. The gNB may use the information. As disclosed above, the gNB may use the information about discarded PDU sets obtained from the UE to perform scheduling suitable for services such as XR, thereby improving low latency characteristics and communication quality.

[0198] Alternatively, the information may be sent from the UE to an application function (AF) or an application server (AS). The information obtained from the UE may also be sent from the gNB to the AF or AS. The gNB may send the information to the AF or AS via the CN. Thus, the AF or AS may use information about the PDU set discarded by the application.

[0199] A method for sending a request for sending the information from the gNB to the UE is disclosed. The CN may send a request for sending the information to the UE. Alternatively, the CN may send a request for sending the information to the gNB. The gNB that receives the request for sending the information may also send the request for sending the information to the UE. Thus, a function of the CN or a node of the CN may send a request for sending information related to the discarded PDU set.

[0200] Alternatively, a request for sending the information may be sent from the AF or AS to the UE. A request for sending the information may be sent from the AF or AS to the gNB. The AF or AS may send a request for sending the information to the gNB via the CN. The gNB that receives the request for sending the information may also send a request for sending the information to the UE. Thus, the AF or AS or the application may send a request for sending information related to the discarded PDU set.

[0201] According to the third embodiment, for example, it is possible to execute control of a communication system suitable for services such as XR.

[0202] Implementation method 4. When UE movement occurs, downlink data is transmitted from the mobile source base station to the mobile target base station. Therefore, there is a situation where data is transmitted from the middle packet of the PDU set. However, the mobile target base station does not recognize the timing of the mobile source base station sending the first data in the PDU set. Or, the mobile target base station does not recognize the timing of the mobile source base station receiving the first data in the PDU set from the UPF. Therefore, the following problem arises: the mobile target base station cannot determine whether all the data of the PDU set is sent within the packet delay budget, as a result, for example, the mobile target base station cannot perform priority control, scheduling control and / or data discard control.

[0203] This embodiment 4 discloses a method for solving the above-mentioned problem.

[0204] That is, in the method shown in this embodiment 4, the mobile source base station notifies the mobile target base station of information related to the timing of sending the first data in the PDU set containing the data to be transmitted. The mobile source base station notifies the mobile target base station of information related to the timing of receiving the first data in the PDU set from the UPF. The above method can be applied to downlink communication, for example.

[0205] Information related to the first data in the PDU set can be set. The mobile source base station can use Xn signaling as a notification method to notify the mobile target base station of the information. For example, the information can be included in the signaling of SN status transfer (SNSTATUS TRANSFER), or can be included in the signaling of early status transfer (EARLY STATUS TRANSFER).

[0206] The mobile source base station can use the user layer protocol used in NG-RAN as a method of notifying the mobile target base station of this information. This information can be processed as user layer data.

[0207] The above-mentioned operation can be applied to uplink communication. For example, the source base station notifies the target base station of information related to the timing of receiving the first data in the PDU set.

[0208] According to the fourth embodiment, the target base station can determine whether all data of the PDU set is transmitted within the packet delay budget, and as a result, for example, the target base station can perform priority control, scheduling control and / or data discard control.

[0209] In the above, the case where UE mobility occurs is disclosed, but it can also be appropriately applied to DC (Dual Connectivity). For example, it can also be appropriately applied in SCG additional processing. It can also be appropriately applied in the transfer processing from MN terminal bearer to SN terminal bearer, or from SN terminal bearer to MN terminal bearer. In DC, the base station can also perform priority control, scheduling control and / or data discard control.

[0210] Implementation method 5. Priorities may be set for PDU sets. Scheduling may be performed using the priorities set for the PDU sets.

[0211] For example, in SPS, when the transmission timings of a part of data of a plurality of PDU sets conflict, the base station may transmit the data of a PDU set having a higher priority.

[0212] As another example, in the CG, when the sending timing of part of the data of multiple PDU sets conflicts, the UE can send the data of a PDU set with a higher priority.

[0213] For example, if part of the data in a PDU set cannot be delivered and exceeds the packet delay budget, the PDU set is discarded, even if the other data in the PDU set is prioritized. In order to solve such a problem, a priority order can be set for each PDU set. For example, instead of prioritizing the other data in the PDU set to be discarded and performing scheduling and other controls, other PDU sets can be prioritized for scheduling and other controls. As a result, the resources allocated to the other data of the PDU set can be allocated to the data of other PDU sets.

[0214] Thus, by performing priority control on each PDU set, more efficient priority control can be performed, thereby improving the efficiency of using wireless resources.

[0215] In the present disclosure, it is recorded as gNB or cell, but unless otherwise specified, it can also be gNB or cell.

[0216] In the present disclosure, gNB can be either MCG or SCG.

[0217] The above-mentioned embodiments and their modifications are merely examples, and the embodiments and their modifications can be freely combined. In addition, arbitrary structural elements of the embodiments and their modifications can be appropriately changed or omitted.

[0218] For example, in the above-mentioned embodiments and their variations, a time slot is an example of a time unit for communication in a fifth generation communication system. A time slot may be a scheduling unit. In the above-mentioned embodiments and their variations, processing recorded in time slot units may be performed in TTI units, subframe units, sub-time slot units, and micro-time slot units.

[0219] For example, the methods disclosed in the above embodiments and their variations can be applied to IAB, can be applied to the communication between the IAB host and the IAB node, and can also be applied to the processing of using Uu in IAB.

[0220] For example, the methods disclosed in the above embodiments and their variations can be applied to SL communication. For example, they can be applied to communication between UE and NW via relay. They can be applied to communication between UE and NW based on L2 relay.

[0221] For example, the methods disclosed in the above embodiments and their variations are not limited to V2X (Vehicle-to-everything) services, but can also be applied to services using SL communication. For example, they can be applied to SL communication used in various services such as proximity-based services, public safety, communication between wearable terminals, and communication between devices in factories.

[0222] Hereinafter, each aspect of the present disclosure will be collectively described as a supplementary note.

[0223] (Supplementary Note 1) A communication system, comprising: a base station corresponding to a fifth generation wireless access system and connected to a core network capable of providing an XR service; and a communication terminal connected to the base station, When the communication terminal uses the XR service via the base station, The communication terminal notifies the base station of information related to characteristics of uplink data transmitted to the base station in communication for utilizing the XR service. (Supplement 2) The communication system as described in Supplement 1 is characterized in that: The base station performs scheduling related to transmission of the uplink data of the communication terminal based on the information related to the uplink data acquired from the communication terminal. (Supplement 3) The communication system as described in Supplement 1 or 2, characterized in that: It is configured to be able to combine a plurality of data of a predetermined unit and transmit and process them as a data set, When transmission of at least one data included in the data set fails, at least one of the base station and the communication terminal discards the data that failed to be transmitted and other data in the data set including the data that failed to be transmitted from a transmission buffer. (Supplement 4) The communication system as described in Supplement 3 is characterized in that: When reception of at least one data included in the data set fails, at least one of the base station and the communication terminal discards data included in the same data set as the data that failed to be received, among the received data. (Supplement 5) The communication system as described in Supplement 3 or 4, characterized in that When data is discarded from a transmission buffer due to a data transmission failure or when data is discarded from a reception buffer due to a data reception failure, the communication terminal notifies the base station of information on a data set including the discarded data. (Supplement 6) The communication system as described in any one of Supplements 3 to 5, characterized in that comprising a plurality of base stations, When a communication terminal connected to a first base station, which is one of the plurality of base stations, switches its connection destination to a second base station, which is one of the plurality of base stations and is different from the first base station, The first base station starts to transmit data with the communication terminal of the switching connection target as the sending destination to the second base station. When the data transmitted to the second base station includes data included in a data set that is identical to data completed to be sent to the communication terminal of the switching connection target, the first base station is notified of relevant information on the sending timing of the initial data included in the data set that is identical to the data transmitted to the second base station. (Supplement 7) The communication system as described in any one of Supplements 3 to 6, characterized in that: prioritizing said data sets, The base station schedules data transmission to the communication terminal based on the priority order. Description of symbols

[0224] 202 communication terminal device (mobile terminal), 210 communication system, 213, 240-1, 240-2, 750 base station device (NR base station, base station), 214 5G core unit, 215 central unit, 216 distributed unit, 217 central unit for control layer, 218 central unit for user layer, 219 TRP, 301, 403 protocol processing unit, 302 application unit, 304, 405 encoding unit, 305, 406 modulation unit, 306, 407 frequency conversion unit, 307-1 to 307-4, 408-1 to 408-4 antennas, 308, 409 demodulation unit, 309, 410 decoding unit, 310, 411, 526 control unit, 401EPC communication unit, 402 other base station communication unit, 412 5GC communication unit, 521 data network communication unit, 522 base station communication unit, 523 user layer communication unit, 523-1PDU processing unit, 523-2 mobile anchoring unit, 525 control layer control unit, 525-1NAS security unit, 525-2 idle state mobile management unit, 527 session management unit, 527-1PDU session control unit, 527-2UEIP address allocation unit, 751-1~751-8 beams, 752 cell.

Claims

1. A communication system, characterized in that: Include: A base station, which corresponds to a fifth generation wireless access system and is connected to a core network capable of providing XR services; as well as a communication terminal connected to the base station, When the communication terminal uses the XR service via the base station, The communication terminal notifies the base station of information related to characteristics of uplink data transmitted to the base station in communication for utilizing the XR service.

2. The communication system according to claim 1, characterized in that The base station performs scheduling related to transmission of the uplink data of the communication terminal based on the information related to the uplink data acquired from the communication terminal.

3. The communication system according to claim 1, wherein: It is configured to be able to combine a plurality of data of a predetermined unit and transmit and process them as a data set, When at least one data included in the data set fails to be transmitted, at least one of the base station and the communication terminal discards the data that failed to be transmitted and other data in the data set including the data that failed to be transmitted from a transmission buffer.

4. The communication system according to claim 3, characterized in that When reception of at least one data included in the data set fails, at least one of the base station and the communication terminal discards data included in the same data set as the data that failed to be received, among the received data.

5. The communication system according to claim 3 or 4, characterized in that: When data is discarded from a transmission buffer due to a data transmission failure or when data is discarded from a reception buffer due to a data reception failure, the communication terminal notifies the base station of information on a data set including the discarded data.

6. The communication system according to claim 3, characterized in that comprising a plurality of base stations, When a communication terminal connected to a first base station, which is one of the plurality of base stations, switches its connection destination to a second base station, which is one of the plurality of base stations and is different from the first base station, The first base station starts to transmit data with the communication terminal of the switching connection target as the sending destination to the second base station. When the data transmitted to the second base station includes data included in the same data set as the data completed to be sent to the communication terminal of the switching connection target, the first base station is notified of relevant information on the sending timing of the initial data included in the same data set as the data transmitted to the second base station.

7. The communication system according to claim 3, characterized in that prioritizing said data sets, The base station schedules data transmission to the communication terminal based on the priority order.

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