Communication system

Abstract

The present invention provides a communication system supporting a 5th Generation wireless access system and including a base station 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 through the base station, the communication terminal notifies the base station of information pertaining to a characteristic of uplink data to be transmitted to the base station in communication for using the XR service.

Description

communication systems

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

[0002] The 3GPP (3rd Generation Partnership Project), a standardization organization for mobile communication systems, is studying a fifth-generation (hereinafter sometimes referred to as "5G") wireless access system 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 being studied based on the LTE system and the LTE-A system.

[0003] For example, in Europe, an organization called METIS has compiled 5G requirements (see Non-Patent Document 3). The requirements for a 5G wireless access system are that it must have 1000 times the system capacity, 100 times the data transmission speed, one-fifth the data processing delay, and 100 times the number of simultaneous connections of communication terminals compared to an LTE system, while also achieving further reductions in power consumption and cost reductions for the equipment (see Non-Patent Document 3).

[0004] In order to meet such demands, 3GPP is currently studying 5G standards (see Non-Patent Documents 4 to 23).

[0005] The NR access method uses OFDM (Orthogonal Frequency Division Multiplexing) in the downlink direction and OFDM and DFT-s-OFDM (Discrete Fourier Transform-spread-OFDM) in the uplink direction. Also, like LTE and LTE-A, the 5G system does not include circuit switching and is only a packet communication method.

[0006] NR allows the use of higher frequencies than LTE in order to improve transmission speeds and reduce processing delays.

[0007] In NR, which may use higher frequencies than LTE, cell coverage is ensured by forming a narrow beam-shaped transmission and reception range (beam forming) and changing the direction of the beam (beam sweeping).

[0008] The decisions made by 3GPP regarding the frame structure in an NR system, as described in Non-Patent Document 1 (Chapter 5), are explained using Figure 1. Figure 1 is an explanatory diagram showing the structure of a radio frame used in an NR communication system. In Figure 1, one radio frame is 10 ms. The radio frame is divided into 10 equally sized subframes. The NR frame structure supports one or more numerologies, i.e., one or more subcarrier spacings (SCSs). In NR, one subframe is 1 ms long, and one slot consists of 14 symbols, regardless of the subcarrier spacing. Furthermore, the number of slots included in one subframe is one when the subcarrier spacing is 15 kHz, and the number of slots at other subcarrier spacings increases in proportion to the subcarrier spacing (see Non-Patent Document 11 (3GPP TS38.211)).

[0009] 3GPP's decisions regarding channel configuration in NR systems are described in Non-Patent Document 2 (Chapter 5) and Non-Patent Document 11.

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

[0011] Downlink synchronization signals in NR include a primary synchronization signal (P-SS) and a secondary synchronization signal (S-SS). Synchronization signals are transmitted from base stations as synchronization signal bursts (hereinafter sometimes referred to as SS bursts) at predetermined intervals and for a predetermined duration. SS bursts are composed of synchronization signal blocks (hereinafter sometimes referred to as SS blocks) for each beam of the base station.

[0012] The base station transmits the SS block of each beam by changing the beam during the duration of the SS burst. The SS block consists of the P-SS, S-SS, and PBCH.

[0013] The Physical Downlink Control Channel (PDCCH) is a channel for downlink transmission from a base station to a communication terminal. The PDCCH carries downlink control information (DCI). The DCI includes resource allocation information for a Downlink Shared Channel (DL-SCH), which is one of the transport channels described below, resource allocation information for a Paging Channel (PCH), which is one of the transport channels described below, and Hybrid Automatic Repeat reQuest (HARQ) information related to the DL-SCH. The DCI may also include an uplink scheduling grant. The DCI may also include an acknowledgement (Ack) / negative acknowledgement (Nack), which is a response signal to the uplink transmission. In addition, in order to flexibly switch between DL and UL within a slot, the DCI may include a slot format indication (SFI). The PDCCH or the DCI is also called an L1 / L2 control signal.

[0014] In NR, a time-frequency region that is a candidate for including a PDCCH is provided. This region is called a control resource set (CORESET). A communication terminal monitors the CORESET and acquires a PDCCH.

[0015] The Physical Downlink Shared Channel (PDSCH) is a channel for downlink transmission from a base station to a communication terminal. The Downlink Shared Channel (DL-SCH), which is a transport channel, and the PCH, which is a transport channel, are mapped to the PDSCH.

[0016] The Physical Uplink Control Channel (PUCCH) is a channel for uplink transmission from a communication terminal to a base station. The PUCCH carries uplink control information (UCI). The UCI includes Ack / Nack, which is a response signal to a downlink transmission, CSI (Channel State Information), a scheduling request (SR), and the like. The CSI is composed of a Rank Indicator (RI), a Precoding Matrix Indicator (PMI), and a CQI (Channel Quality Indicator) report. The RI is rank information of a channel matrix in MIMO (Multiple Input Multiple Output). The PMI is information on a precoding weight matrix used in MIMO. The CQI is quality information indicating the quality of received data or the quality of a communication path. The UCI may be carried by the PUSCH, which will be described later. The PUCCH or UCI is also called an 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. The Uplink Shared Channel (UL-SCH), which is one of the transport channels, is mapped to the PUSCH.

[0018] A physical random access channel (PRACH) is a channel for uplink transmission from a communication terminal to a base station. The PRACH carries a random access preamble.

[0019] A downlink reference signal (RS) is a known symbol in an NR communication system. The following four types of downlink reference signals are defined: a demodulation reference signal (DM-RS), which is a UE-specific reference signal, a phase tracking reference signal (PT-RS), a positioning reference signal (PRS), and a channel state information reference signal (CSI-RS). Measurements of the physical layer of a communication terminal include reference signal received power (RSRP) measurement and reference signal received quality (RSRQ) measurement.

[0020] Similarly, the uplink reference signal is a known symbol in an NR communication system. The following three types of uplink reference signals are defined: a data demodulation reference signal (DM-RS), a phase tracking reference signal (PT-RS), and a sounding reference signal (SRS).

[0021] The transport channels described in Non-Patent Document 2 (Chapter 5) will be described below. Among the downlink transport channels, a broadcast channel (BCH) is broadcast to the entire coverage of the base station (cell). The BCH is mapped to a physical broadcast channel (PBCH).

[0022] Retransmission control using HARQ is applied to the Downlink Shared Channel (DL-SCH). The DL-SCH can be broadcast to the entire coverage of the base station (cell). The DL-SCH supports dynamic or semi-static resource allocation. Semi-static resource allocation is also called semi-persistent scheduling. The DL-SCH supports discontinuous reception (DRX) in communication terminals to reduce power consumption of the communication terminals. The DL-SCH is mapped to the Physical Downlink Shared Channel (PDSCH).

[0023] The Paging Channel (PCH) supports DRX of communication terminals to enable low power consumption of the communication terminals. The PCH is required to broadcast to the entire coverage of the base station (cell). The PCH is mapped to physical resources such as the Physical Downlink Shared Channel (PDSCH) that can be dynamically used for traffic.

[0024] Among the uplink transport channels, the uplink shared channel (UL-SCH) is subject to retransmission control using HARQ. The UL-SCH supports dynamic or semi-static resource allocation. Semi-static resource allocation is also called configured grant. The UL-SCH is mapped to the physical uplink shared channel (PUSCH).

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

[0026] The following describes HARQ. HARQ is a technology that improves the communication quality of a transmission path by combining Automatic Repeat reQuest (ARQ) and Forward Error Correction. HARQ has the advantage that error correction functions effectively through retransmission even for transmission paths whose communication quality varies. In particular, by combining the reception result of the initial transmission and the reception result of the retransmission when retransmitting, it is possible to obtain further quality improvement.

[0027] An example of a retransmission method will be described below. If the receiving side is unable to decode the received data correctly, in other words, if a CRC (Cyclic Redundancy Check) error occurs (CRC=NG), the receiving side will send a "Nack" to the transmitting side. The transmitting side, having received the "Nack", will retransmit the data. If the receiving side is able to decode the received data correctly, in other words, if no CRC error occurs (CRC=OK), the receiving side will send an "Ack" to the transmitting side. The transmitting side, having received the "Ack", will send the next data.

[0028] Another example of a retransmission method will be described. If a CRC error occurs on the receiving side, the receiving side requests a retransmission from the transmitting side. The retransmission request is made by toggling an NDI (New Data Indicator). The transmitting side, upon receiving the retransmission request, retransmits the data. If no CRC error occurs on the receiving side, no retransmission request is made. If the transmitting side does not receive a retransmission request for a predetermined period of time, it assumes that no CRC error occurred on the receiving side.

[0029] The logical channels described in Non-Patent Document 1 (Chapter 6) are explained below. The Broadcast Control Channel (BCCH) is a downlink channel for broadcasting system control information. The BCCH, which is a logical channel, is mapped to the broadcast channel (BCH) or the downlink shared channel (DL-SCH), which are transport channels.

[0030] The Paging Control Channel (PCCH) is a downlink channel for transmitting paging information and changes to system information. 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 for transmitting control information between a communication terminal and a base station. The CCCH is used when the communication terminal does not have an RRC connection with the network. In the downlink direction, the CCCH is mapped to the Downlink Shared Channel (DL-SCH), which is a transport channel. In the uplink direction, the CCCH is mapped to the Uplink Shared Channel (UL-SCH), which is a transport channel.

[0032] A Dedicated Control Channel (DCCH) is a channel that transmits dedicated control information between a communication terminal and a network in a one-to-one relationship. The DCCH is used when the communication terminal has an RRC connection with the network. The DCCH is mapped to an uplink shared channel (UL-SCH) in the uplink and to a downlink shared channel (DL-SCH) in the downlink.

[0033] A Dedicated Traffic Channel (DTCH) is a point-to-point communication channel for transmitting user information to a communication terminal. DTCH exists in both uplink and downlink. In uplink, DTCH is mapped to an uplink shared channel (UL-SCH) and in downlink, it is mapped to a downlink shared channel (DL-SCH).

[0034] The location of a communication terminal is tracked in units of an area consisting of one or more cells. Location tracking is performed to track the location of the communication terminal even when it is in standby mode and to call the communication terminal, in other words, to enable the communication terminal to receive calls. The area for tracking the location of this communication terminal is called a Tracking Area (TA).

[0035] In NR, paging of communication terminals within a range that is smaller than a tracking area is supported. This range is called a RAN Notification Area (RNA). Paging of communication terminals in the RRC_INACTIVE state, which will be described later, is performed within this range.

[0036] In NR, in order to support wide frequency bandwidths (transmission bandwidths), carrier aggregation (CA) is being considered, which aggregates (also referred to as "aggregation") two or more component carriers (CCs). CA is described in Non-Patent Document 1.

[0037] When CA is configured, a communication terminal (UE) has only one RRC connection with the network (NW). In the RRC connection, one serving cell provides NAS mobility information and security input. This cell is called a primary cell (PCell). Depending on the UE's capabilities, a secondary cell (SCell) is configured to form a serving cell set together with the PCell. A serving cell set consisting of one PCell and one or more SCells is configured for one UE.

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

[0039] Of the base stations performing dual connectivity (DC), one may be referred to as a "master base station (Master Node: MN)" and the other as a "secondary base station (Secondary Node: SN)." Serving cells configured by the master base station may be collectively referred to as a master cell group (MCG), and serving cells configured by secondary base stations may be collectively referred to as a secondary cell group (SCG). In DC, the primary cell in the MCG or SCG is referred to as a special cell (SpCell or SPCell). The special cell in the MCG is referred to as a PCell, and the special cell in the SCG is referred to as a primary SCG cell (PSCell).

[0040] In addition, in NR, the base station pre-sets a portion of the carrier frequency band (hereinafter sometimes referred to as the Bandwidth Part (BWP)) for the UE, and the UE transmits and receives data to and from the base station using this BWP, thereby reducing power consumption in the UE.

[0041] Additionally, 3GPP is considering supporting services (or applications) using side link (SL) communication (also referred to as PC5 communication) in both the Evolved Packet System (EPS) (described later) and the 5G core system (see Non-Patent Documents 1, 2, 26 to 28). SL communication involves communication between terminals. Services using SL communication include, for example, vehicle-to-everything (V2X) services and proximity services. In SL communication, not only direct communication between terminals but also communication between a UE and a network via a relay has been proposed (see Non-Patent Documents 26 and 28).

[0042] The physical channels used for SL (see Non-Patent Documents 2 and 11) are as follows: The physical sidelink broadcast channel (PSBCH) carries information related to the system and synchronization and is transmitted from the UE.

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

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

[0045] The physical sidelink feedback channel (PSFCH) carries HARQ feedback on the sidelink from a UE that received a PSSCH transmission to the UE that transmitted the PSSCH.

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

[0047] The Sidelink Shared Channel (SL-SCH) supports broadcast transmissions. The SL-SCH supports both UE autonomous resource selection and base station scheduled resource allocation. UE autonomous resource selection involves a collision risk, whereas when the UE is allocated dedicated resources by the base station, there is no collision. The SL-SCH also supports dynamic link adaptation by changing transmit power, modulation, and coding. The SL-SCH is mapped to the PSSCH, which is a physical channel.

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

[0049] The Sidelink Traffic Channel (STCH) is a point-to-multipoint traffic channel for transmitting user information from one UE to other UEs. The STCH is used only by UEs with sidelink communication capability and UEs with V2X sidelink communication capability. Point-to-point communication between two sidelink-capable UEs is also realized by the STCH. The STCH is mapped to the SL-SCH, a transport channel.

[0050] The Sidelink Control Channel (SCCH) is a control channel for transmitting control information from one UE to another UE. The SCCH is mapped to the SL-SCH, which is a transport channel.

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

[0052] In unicast communication and groupcast communication in SL, HARQ feedback (Ack / Nack), CSI reporting, etc. are supported.

[0053] In addition, 3GPP is considering integrated access and backhaul (IAB), which performs both the access link between a UE and a base station and the backhaul link between base stations wirelessly (see Non-Patent Documents 2, 20, and 29).

[0054] 3GPP has proposed several new technologies. For example, communication methods suitable for XR (eXtended Reality) and cloud gaming services have been discussed (Non-Patent Document 30), and XR recognition methods, XR-specific low power consumption methods, and XR-specific capacity improvement methods have been proposed that take into account the characteristics of XR traffic (e.g., non-integer periodicity, data generation time fluctuation (jitter) characteristics, data volume fluctuation characteristics, low latency characteristics, etc.) (Non-Patent Documents 31, 32, 33).

[0055] 3GPP TS36.300 V16.7.03GPP TS38.300 V16.8.0“Scenarios, requirements and KPIs for 5G mobile and wireless system”、ICT-317669-METIS / D1.13GPP TR23.799 V14.0.03GPP TR38.801 V14.0.03GPP TR38.802 V14.2.03GPP TR38.804 V14.0.03GPP TR38.912 V16.0.03GPP RP-1721153GPP TS23.501 V17.3.03GPP TS38.211 V17.0.03GPP TS38.212 V17.0.03GPP TS38.213 V17.0.03GPP TS38.214 V17.0.03GPP TS38.321 V16.7.03GPP TS38.322 V16.2.03GPP TS38.323 V16.6.03GPP TS37.324 V16.3.03GPP TS38.331 V16.7.03GPP TS38.401 V16.8.03GPP TS38.413 V16.8.03GPP TS37.340 V16.8.03GPP TS38.423 V16.8.03GPP TS38.305 V16.7.03GPP TS23.273 V17.3.03GPP TR23.703 V12.0.03GPP TS23.287 V17.2.03GPP TS23.303 V17.0.03GPP TS38.340 V16.5.03GPP RP-2135873GPP R1-22046563GPP R1-22031323GPP R1-22050563GPP TR38.838 V17.0.0

[0056] 5G wireless access systems provide communications for a wide variety of services. Enabling communications suitable for XR and cloud gaming services is also an important issue. To enable such communications, a communication method that takes into account the characteristics of XR traffic (e.g., non-integer periodicity, data generation time fluctuation (jitter) characteristics, data volume fluctuation characteristics, low latency characteristics, etc.) is required (Non-Patent Document 30). In conventional communication methods, the network side has no means to recognize such characteristics of data generated on the UE side. Therefore, conventional communication methods are not suitable for the characteristics of XR traffic, resulting in increased latency and degradation of communication quality.

[0057] In view of the above-mentioned problems, one of the objectives of the present disclosure is to realize a communication system suitable for communication having characteristics such as XR traffic.

[0058] The communication system according to the present disclosure is compatible with the fifth generation wireless access system and includes a base station connected to a core network capable of providing the XR service, and a communication terminal connected to the base station, and when the communication terminal uses the XR service via the base station, the communication terminal notifies the base station of information regarding the characteristics of uplink data transmitted to the base station in communication for using the XR service.

[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 the accompanying drawings.

[0061] 1 is an explanatory diagram showing the configuration of a radio frame used in an NR communication system. FIG. 2 is a block diagram showing the overall configuration of an NR communication system 210 being discussed in 3GPP. FIG. 3 is a diagram showing the configuration of a DC by a base station connected to an NG core. FIG. 4 is a block diagram showing the configuration of a mobile terminal 202 shown in FIG. 2. FIG. 5 is a block diagram showing the configuration of a base station 213 shown in FIG. 2. FIG. 6 is a block diagram showing the configuration of a 5GC unit. FIG. 7 is a flowchart showing an overview of the process from cell search to standby operation performed by a communication terminal (UE) in an NR communication system. FIG. 8 is a diagram showing an example of the configuration of a cell in an NR system. FIG. 9 is a connection configuration diagram showing an example of the connection configuration of a terminal in SL communication. FIG. 10 is a connection configuration diagram showing an example of the connection configuration of a base station that supports access / backhaul integration. FIG. 11 is a diagram showing an example of a sequence of a method for transmitting information regarding UL data and preference information regarding CG settings from a UE to a gNB in ​​accordance with a first embodiment. FIG. 12 is a diagram showing an example of a sequence of a method for transmitting information regarding UL data and DL data from a gNB to an AF in accordance with a first embodiment.

[0062] Embodiment 1. Figure 2 is a block diagram showing the overall configuration of an NR communication system 210 being discussed in 3GPP. Figure 2 will be explained. The radio access network is called an NG-RAN (Next Generation Radio Access Network) 211. A mobile terminal device (hereinafter referred to as a "mobile terminal (User Equipment: UE)") 202, which is a communication terminal device, is capable of wireless communication with a base station device (hereinafter referred to as an "NR base station (NG-RAN NodeB: gNB)") 213, and transmits and receives signals via wireless communication. The NG-RAN 211 is composed of one or more NR base stations 213.

[0063] Here, the term "communication terminal device" includes not only mobile terminal devices such as mobile cell phone terminal devices, but also stationary devices such as sensors. In the following description, the term "communication terminal device" may be simply referred to as a "communication terminal."

[0064] An access stratum (AS) protocol is terminated between the UE 202 and the NG-RAN 211. Examples of AS protocols that are used include radio resource control (RRC), service data adaptation protocol (SDAP), packet data convergence protocol (PDCP), radio link control (RLC), medium access control (MAC), and physical layer (PHY). RRC is used in the control plane (hereinafter sometimes referred to as the C-plane or C-plane), SDAP is used in the user plane (hereinafter sometimes referred to as the U-plane or U-plane), and PDCP, MAC, RLC, and PHY are used in both the C-plane and the U-plane.

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

[0066] In RRC_IDLE, PLMN (Public Land Mobile Network) selection, system information (SI) broadcast, paging, cell re-selection, mobility, etc. are performed. In RRC_CONNECTED, the mobile terminal has an RRC connection and can transmit and receive data with the network. In addition, in RRC_CONNECTED, handover (HO), measurement of neighbor cells, etc. are performed. In RRC_INACTIVE, the connection between the 5G core unit 214 and the NR base station 213 is maintained, and system information (SI) broadcast, paging, cell re-selection, mobility, etc. are performed.

[0067] The gNB 213 is connected to a 5G core unit (hereinafter sometimes referred to as the "5GC unit") 214, which includes an Access and Mobility Management Function (AMF), a Session Management Function (SMF), or a User Plane Function (UPF), via an NG interface. Control information and / or user data is communicated between the gNB 213 and the 5GC unit 214. The NG interface is a collective 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. Multiple 5GC units 214 may be connected to one gNB 213. The gNBs 213 are connected via an Xn interface, and control information and / or user data are communicated between the gNBs 213.

[0068] The 5GC unit 214 is a higher-level device, specifically a higher-level node, and controls the connection between the NR base station 213 and the mobile terminal (UE) 202, distributes paging signals to one or more NR base stations (gNB) 213 and / or LTE base stations (E-UTRAN NodeB: eNB), and performs other functions. The 5GC unit 214 also performs mobility control in the idle state. The 5GC unit 214 manages the tracking area list when the mobile terminal 202 is in the idle state, in the inactive state, and in the active state. The 5GC unit 214 initiates a paging protocol by transmitting a paging message to a cell belonging to the tracking area in which the mobile terminal 202 is registered.

[0069] The gNB 213 may configure one or more cells. When one gNB 213 configures multiple cells, each of the cells is configured to be able to communicate with the UE 202.

[0070] The gNB 213 may be divided into a central unit (hereinafter, sometimes referred to as CU) 215 and a distributed unit (hereinafter, sometimes referred to as DU) 216. One CU 215 is configured within the gNB 213. One or more DUs 216 are configured within the gNB 213. One DU 216 configures one or more cells. The CU 215 is connected to the DU 216 via an F1 interface, and control information and / or user data is communicated between the CU 215 and the DU 216. The F1 interface consists of an F1-C interface and an F1-U interface. The CU 215 is responsible for the functions of the RRC, SDAP, and PDCP protocols, and the DU 216 is responsible for the functions of the RLC, MAC, and PHY protocols. One or more TRPs (Transmission Reception Points) 219 may be connected to the DU 216. The TRP 219 transmits and receives radio signals to and from the UE.

[0071] The CU 215 may be divided into a C-plane CU (CU-C) 217 ​​and a U-plane CU (CU-U) 218. One CU-C 217 is configured within the CU 215. One or more CU-Us 218 are configured within 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] In a 5G communication system, a Unified Data Management (UDM) function and a Policy Control Function (PCF) described in Non-Patent Document 10 (3GPP TS23.501) may be included. The UDM and / or PCF may be included in the 5GC unit 214 in FIG. 2 .

[0073] In a 5G communication system, a Location Management Function (LMF) described in Non-Patent Document 24 (3GPP TS 38.305) may be provided. The LMF may be connected to a base station via an AMF as disclosed in Non-Patent Document 25 (3GPP TS 23.273).

[0074] A 5G communication system may include a Non-3GPP Interworking Function (N3IWF) described in Non-Patent Document 10 (3GPP TS23.501). The N3IWF may terminate an Access Network (AN) between the UE and the N3IWF in non-3GPP access between the UE and the N3IWF.

[0075] FIG. 3 is a diagram showing a DC (dual connectivity) configuration connected to an NG core. In FIG. 3, solid lines indicate U-Plane connections, and dashed lines indicate C-Plane connections. In FIG. 3, the master base station 240-1 may be a gNB or an eNB. Furthermore, the secondary base station 240-2 may be a gNB or an eNB. For example, in FIG. 3, a DC configuration in which the master base station 240-1 is a gNB and the secondary base station 240-2 is an eNB may be referred to as NG-EN-DC. In FIG. 3, an example is shown in which the U-Plane connection between the 5GC unit 214 and the secondary base station 240-2 is performed via the master base station 240-1, but it may also be performed directly between the 5GC unit 214 and the secondary base station 240-2. 3, an EPC (Evolved Packet Core), which is a core network connected to the LTE system and the LTE-A system, may be connected to the master base station 240-1 instead of the 5GC unit 214. A U-Plane connection may be directly established between the EPC and the secondary base station 240-2.

[0076] FIG. 4 is a block diagram showing the configuration of mobile terminal 202 shown in FIG. 2. The transmission process of mobile terminal 202 shown in FIG. 4 will be described. First, control data from control unit 310 and user data from application unit 302 are sent to protocol processing unit 301. Buffering of the control data and user data may be performed. Buffers for the control data and user data may be provided in control unit 310, application unit 302, or protocol processing unit 301. Protocol processing unit 301 performs protocol processing such as SDAP, PDCP, RLC, and MAC, for example, determining a destination base station in DC, and adding a header for each protocol. The protocol-processed data is passed to encoder unit 304, where it is subjected to encoding such as error correction. Some data may be output directly from protocol processing unit 301 to modulation unit 305 without being encoded. The data encoded by encoder unit 304 is modulated by modulation unit 305. Precoding in MIMO may be performed by modulation unit 305. The modulated data is converted into a baseband signal, and then output to frequency conversion section 306, where it is converted into a radio transmission frequency. Then, the transmission signal is transmitted from antennas 307-1 to 307-4 to base station 213. Although the example in FIG. 4 shows a case where the number of antennas is four, the number of antennas is not limited to four.

[0077] Furthermore, the reception process of the mobile terminal 202 is performed as follows. Radio signals from the base station 213 are received by the antennas 307-1 to 307-4. The received signals are converted from a radio reception frequency to a baseband signal by the frequency conversion unit 306, and demodulated by the demodulation unit 308. The demodulation unit 308 may also perform weight calculation and multiplication processing. The demodulated data is passed to the decoder unit 309, where decoding processes such as error correction are performed. The decoded data is passed to the protocol processing unit 301, where protocol processing such as MAC, RLC, PDCP, and SDAP is performed, for example, operations such as removing headers in each protocol. Of the data that has undergone protocol processing, the control data is passed to the control unit 310, and the user data is passed to the application unit 302.

[0078] A series of processes in the mobile terminal 202 is controlled by a control unit 310. Therefore, the control unit 310 is also connected to each of the units 302, 304 to 309, although this is omitted in FIG.

[0079] Each unit of the mobile terminal 202, such as the control unit 310, protocol processing unit 301, encoder unit 304, and decoder unit 309, is implemented by a processing circuit including, for example, a processor and memory. For example, the control unit 310 is implemented by a processor executing a program describing a series of processes performed by the mobile terminal 202. The program describing the series of processes performed by the mobile terminal 202 is stored in memory. Examples of memory include non-volatile or volatile semiconductor memory such as RAM (Random Access Memory), ROM (Read Only Memory), and flash memory. Each unit of the mobile terminal 202, such as the control unit 310, protocol processing unit 301, encoder unit 304, and decoder unit 309, may be implemented by a dedicated processing circuit such as an FPGA (Field Programmable Gate Array), an ASIC (Application Specific Integrated Circuit), or a DSP (Digital Signal Processor). In FIG. 4, the number of antennas used by the mobile terminal 202 for transmission and the number of antennas used for reception may be the same or different.

[0080] 5 is a block diagram showing the configuration of the base station 213 shown in FIG. 2. The transmission process of the base station 213 shown in FIG. 5 will be described. The EPC communication unit 401 transmits and receives data between the base station 213 and the EPC. The 5GC communication unit 412 transmits and receives data between the base station 213 and the 5GC (such as the 5GC unit 214). The other base station communication unit 402 transmits and receives data with other base stations. The EPC communication unit 401, the 5GC communication unit 412, and the other base station communication unit 402 each exchange information with the protocol processing unit 403. Control data from the control unit 411, and user data and control data from the EPC communication unit 401, the 5GC communication unit 412, and the other base station communication unit 402 are sent to the protocol processing unit 403. Buffering of the control data and user data may be performed. Buffers for control data and user data may be provided in the control unit 411, the EPC communication unit 401, the 5GC communication unit 412, or the other base station communication unit 402.

[0081] The protocol processing unit 403 performs protocol processing such as SDAP, PDCP, RLC, MAC, etc., such as routing transmission data in DC, etc., and adding headers for each protocol. The protocol-processed data is passed to the encoder unit 405, where it is subjected to encoding processing such as error correction. Some data may be output directly from the protocol processing unit 403 to the modulation unit 406 without being encoded. Data may also be sent from the protocol processing unit 403 to the other base station communication unit 402. For example, in DC, data sent from the 5GC communication unit 412 or the EPC communication unit 401 may be sent to another base station, such as a secondary base station, via the other base station communication unit 402. The encoded data is modulated by the modulation unit 406. The modulation unit 406 may also perform MIMO precoding. The modulated data is converted into a baseband signal, and then output to the frequency conversion unit 407, where it is converted into a radio transmission frequency. Thereafter, the transmission signals are transmitted from antennas 408-1 to 408-4 to one or more mobile terminals 202. Although the number of antennas is four in the example shown in Fig. 5, the number of antennas is not limited to four.

[0082] Furthermore, the reception process of the base station 213 is performed as follows. Radio signals from one or more mobile terminals 202 are received by antennas 408-1 to 408-4. The received signals are converted from a radio reception frequency to a baseband signal by a frequency conversion unit 407, and demodulated by a demodulation unit 409. The demodulated data is passed to a decoder unit 410, where decoding processes such as error correction are performed. The decoded data is passed to a protocol processing unit 403, where protocol processes such as MAC, RLC, PDCP, and SDAP are performed, for example, operations such as removing headers in each protocol. Of the data that has undergone protocol processing, control data is passed to the control unit 411, 5GC communication unit 412, EPC communication unit 401, or other base station communication unit 402, and user data is passed to the 5GC communication unit 412, EPC communication unit 401, or other base station communication unit 402. Data sent from the other base station communication unit 402 may 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 another base station in DC.

[0083] A series of processes in the base station 213 is controlled by a control unit 411. Therefore, the control unit 411 is also connected to each of the units 401, 402, 405 to 410, and 412, although this is omitted in FIG.

[0084] Each unit of the base station 213, for example, 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 encoder unit 405, and the decoder unit 410, is realized 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 above-mentioned mobile terminal 202. In Fig. 5, the number of antennas used by the base station 213 for transmission and the number of antennas used for reception may be the same or different.

[0085] As an example of the configuration of the CU 215 shown in Fig. 2, a configuration in which a DU communication unit is provided is sometimes used, excluding the encoder unit 405, modulation unit 406, frequency conversion unit 407, antennas 408-1 to 408-4, demodulation unit 409, and decoder unit 410 shown in Fig. 5. The DU communication unit is connected to a protocol processing unit 403. The protocol processing unit 403 in the CU 215 performs protocol processing such as PDCP and SDAP.

[0086] As an example of the configuration of the DU 216 shown in Fig. 2, a configuration in which a CU communication unit is provided may be used, excluding the EPC communication unit 401, other base station communication unit 402, and 5GC communication unit 412 shown in Fig. 5. The CU communication unit is connected to a protocol processing unit 403. The protocol processing unit 403 in the DU 216 performs protocol processing such as PHY, MAC, and RLC.

[0087] FIG. 6 is a block diagram showing the configuration of the 5GC unit. FIG. 6 shows the configuration of the 5GC unit 214 shown in FIG. 2 described above. FIG. 6 shows a case where the 5GC unit 214 shown in FIG. 2 includes an AMF configuration, an SMF configuration, and a UPF configuration. In the example shown in FIG. 6, the AMF may have the function of the control plane control unit 525, the SMF may have the function of the session management unit 527, and the UPF may have the functions of the user plane communication unit 523 and the Data Network communication unit 521. The Data Network communication unit 521 transmits and receives data between the 5GC unit 214 and the Data Network. The base station communication unit 522 transmits and receives data via the NG interface between the 5GC unit 214 and the base station 213. User data sent from the Data Network is passed from the Data Network communication unit 521 to the base station communication unit 522 via the user plane communication unit 523, and then transmitted to one or more base stations 213. User data sent from the base station 213 is passed from the base station communication unit 522 to the Data Network communication unit 521 via the user plane communication unit 523, and then transmitted to the Data Network.

[0088] The control data sent from the base station 213 is passed from the base station communication unit 522 to the control plane control unit 525. The control plane control unit 525 may pass the control data to the session management unit 527. The control data may be sent from the Data Network. The control data sent from the Data Network may be sent from the Data Network communication unit 521 to the session management unit 527 via the user plane communication unit 523. The session management unit 527 may send the control data to the control plane control unit 525.

[0089] The user plane control unit 523 includes a PDU processing unit 523-1, a mobility anchoring unit 523-2, etc., and performs general processing for the user plane (hereinafter sometimes referred to as U-Plane). The PDU processing unit 523-1 processes data packets, for example, transmitting and receiving packets to and from the Data Network communication unit 521, and transmitting and receiving packets to and from the base station communication unit 522. The mobility anchoring unit 523-2 is responsible for anchoring the data path during UE mobility.

[0090] The session management unit 527 manages the PDU session established 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 assigns an IP address to the mobile terminal 202, etc.

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

[0092] A series of processes of the 5GC unit 214 is controlled by a control unit 526. Therefore, although the control unit 526 is omitted in Fig. 6, it is connected to each unit 521 to 523, 525, and 527. Like the control unit 310 of the mobile terminal 202 described above, each unit of the 5GC unit 214 is realized by, for example, a processing circuit configured to include a processor and 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. Fig. 7 is a flowchart showing an outline of the process from cell search to standby operation performed by a communication terminal (UE) in an NR communication system. When the communication terminal starts a cell search, in step ST601, it synchronizes slot timing and frame timing using a primary synchronization signal (P-SS) and a secondary synchronization signal (S-SS) transmitted from a surrounding base station.

[0094] P-SS and S-SS are collectively called a synchronization signal (SS). A synchronization code is assigned to the synchronization signal (SS) in one-to-one correspondence with a PCI (Physical Cell Identifier) ​​assigned to each cell. 1008 different PCIs are being considered. A communication terminal synchronizes using these 1008 different PCIs and detects (identifies) the PCI of the synchronized cell.

[0095] In step ST602, the communication terminal receives the PBCH for the next synchronized cell. A master information block (MIB) including cell configuration information is mapped to the BCCH on the PBCH. Therefore, the MIB can be obtained by receiving the PBCH and obtaining the BCCH. Examples of MIB information include a system frame number (SFN), scheduling information for system information block (SIB) 1, subcarrier spacing for SIB1 and the like, and information on the DM-RS position.

[0096] Furthermore, the communication terminal acquires an SS block identifier from the PBCH. A part of the bit string of the SS block identifier is included in the MIB. The remaining bit string is included in an identifier used to generate a sequence of DM-RS associated with the PBCH. The communication terminal acquires the SS block identifier using the MIB included in the PBCH and the sequence of DM-RS associated with the PBCH.

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

[0098] Next, in step ST604, the communication terminal selects the cell with the best reception quality, for example, the cell with the highest reception power, that is, the best cell, from among the one or more cells detected up to step ST603. The communication terminal also selects the beam with the best reception quality, for example, the beam with the highest reception power of the SS block, that is, the best beam. The reception power of the SS block for each SS block identifier is used, for example, to select the best beam.

[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 on access to the cell, cell configuration information, and scheduling information of other SIBs (SIBk: k is an integer greater than or equal to 2). SIB1 also includes a tracking area code (TAC).

[0100] Next, in step ST606, the communication terminal compares the TAC of SIB1 received in step ST605 with the TAC portion of the tracking area identity (TAI) in the tracking area list already held by the communication terminal. The tracking area list is also called a TAI list. The TAI is identification information for identifying a tracking area, and is composed of an MCC (Mobile Country Code), an MNC (Mobile Network Code), and a TAC (Tracking Area Code). The MCC is a country code. The MNC is a network code. The TAC is a tracking area code number.

[0101] If the comparison in step ST606 shows that the TAC received in step ST605 is the same as the TAC included in the tracking area list, the communication terminal enters standby mode in the cell. If the comparison shows that the TAC received in step ST605 is not included in the tracking area list, the communication terminal requests a core network (EPC) including an MME and the like to change the tracking area through the cell in order to perform a Tracking Area Update (TAU).

[0102] An apparatus constituting a core network (hereinafter sometimes referred to as a "core network side apparatus") updates the tracking area list based on the identification number (UE-ID, etc.) of the communication terminal sent from the communication terminal together with a TAU request signal. The core network side apparatus transmits 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 mode in the cell.

[0103] Next, examples of random access methods in a communication system are shown. Four-step random access and two-step random access are used for random access. For each of the four-step and two-step random access methods, there is contention-based random access, i.e., random access in which timing collisions with other mobile terminals may occur, and contention-free random access.

[0104] An example of a collision-based four-step random access method is shown below. In the first step, the mobile terminal transmits 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 assigned to the mobile terminal and notified by the base station.

[0105] In the second step, the base station transmits a random access response to the mobile terminal, which includes uplink scheduling information used in the third step, a terminal identifier used in the uplink transmission in the third step, and the like.

[0106] In the third step, the mobile terminal performs uplink transmission to the base station. The mobile terminal uses the information acquired in the second step for uplink transmission. In the fourth step, the base station notifies the mobile terminal whether or not the collision has been resolved. If the mobile terminal is notified that there is no collision, it ends the random access process. If the mobile terminal is notified that there is a collision, it starts the process over from the first step.

[0107] The contention-free four-step random access method differs from the contention-based four-step random access method in the following points: Prior to the first step, the base station pre-assigns a random access preamble and uplink scheduling to the mobile terminal, and the notification of whether or not contention has been resolved in the fourth step is not required.

[0108] An example of a collision-based two-step random access method is shown below. In the first step, the mobile terminal transmits a random access preamble and performs uplink transmission to the base station. In the second step, the base station notifies the mobile terminal whether there is a collision. If the mobile terminal is notified that there is no collision, it terminates the random access process. If the mobile terminal is notified that there is a collision, it restarts the process from the first step.

[0109] The contention-free two-step random access method differs from the contention-based two-step random access method in the following points: prior to the first step, the base station pre-assigns a random access preamble and uplink scheduling to the mobile terminal, and in the second step, the base station transmits a random access response to the mobile terminal.

[0110] FIG. 8 shows an example of a cell configuration in NR. In an NR cell, narrow beams are formed and transmitted in different directions. In the example shown in FIG. 8, at certain times, base station 750 transmits and receives signals to and from a mobile terminal using beam 751-1. At other times, base station 750 transmits and receives signals to and from a mobile terminal using beam 751-2. In a similar manner, base station 750 transmits and receives signals to and from a mobile terminal using one or more of beams 751-3 to 751-8. In this way, base station 750 forms a wide-area cell 752.

[0111] 8 shows an example in which the number of beams used by the base station 750 is 8, but the number of beams may be different from 8. Also, in the example shown in FIG. 8, the number of beams used simultaneously by the base station 750 is 1, but it may be multiple.

[0112] The concept of Quasi-CoLocation (QCL) is used to identify beams (see Non-Patent Document 14 (3GPP TS38.214)). 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. The information may include types of information regarding the aspects of the beams that can be considered to be the same, such as Doppler shift, Doppler shift spread, mean delay, mean delay spread, and spatial Rx parameters (see Non-Patent Document 14 (3GPP TS38.214)).

[0113] In 3GPP, a side link (SL) is supported for D2D (Device to Device) communication and V2V (Vehicle to Vehicle) communication (see Non-Patent Document 1 and Non-Patent Document 16). The SL is defined by the PC5 interface.

[0114] In order to support unicast and groupcast in addition to broadcast in SL communication, support for PC5-S signaling is being considered (see Non-Patent Document 27 (3GPP TS23.287)). For example, PC5-S signaling is implemented to establish a link for implementing SL, i.e., PC5 communication. The link is implemented in the V2X layer and is also called a Layer 2 link.

[0115] Furthermore, support for RRC signaling in SL communication is being considered (see Non-Patent Document 27 (3GPP TS23.287)). RRC signaling in SL communication is also referred to as PC5 RRC signaling. For example, it has been proposed to notify UE capabilities between UEs performing PC5 communication, or to notify AS layer settings for performing V2X communication using PC5 communication.

[0116] An example of a connection configuration of mobile terminals in SL communication is shown in Fig. 9. In the example shown in Fig. 9, UE 805 and UE 806 exist within the coverage 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 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 a UE and a NW via a relay in SL communication, a UE 805 shown in FIG. 9 relays communication between a UE 811 and a base station 801.

[0118] A configuration similar to that shown in FIG. 4 may be used for a UE that performs relaying. The relaying process in the UE will be described using FIG. 4. The relaying process by UE 805 in communication from UE 811 to base station 801 will be described. A radio signal from UE 811 is received by antennas 307-1 to 307-4. The received signal is converted from a radio reception frequency to a baseband signal by frequency conversion unit 306, and demodulated by demodulation unit 308. Weight calculation and multiplication processing may also be performed by demodulation unit 308. The demodulated data is passed to decoder unit 309, where decoding processing such as error correction is performed. The decoded data is passed to protocol processing unit 301, where protocol processing such as MAC and RLC used for communication with UE 811 is performed, such as removing headers in each protocol. Protocol processing such as RLC and MAC used for communication with base station 801 is also performed, such as adding headers in each protocol. Protocol processing of PDCP and SDAP may be performed in protocol processing unit 301 of UE 811. The protocol-processed data is passed to encoder unit 304, where encoding such as error correction is performed. Some data may be output directly from protocol processing unit 301 to modulation unit 305 without being encoded. The data encoded by encoder unit 304 is modulated by modulation unit 305. Precoding in MIMO may be performed by modulation unit 305. The modulated data is converted into a baseband signal, and then output to frequency conversion unit 306, where it is converted into a radio transmission frequency. Thereafter, a transmission signal is transmitted to base station 801 from antennas 307-1 to 307-4.

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

[0120] 5G base stations can support integrated access and backhaul (IAB) (see Non-Patent Documents 2 and 20). A base station supporting IAB (hereinafter sometimes referred to as an IAB base station) is composed of an IAB donor CU, which is a CU of the base station operating as an IAB donor that provides IAB functions, an IAB donor DU, which is a DU of the base station operating as an IAB donor, and an IAB node connected to the IAB donor DU and to a UE via a radio interface. An F1 interface is provided between the IAB node and the IAB donor CU (see Non-Patent Document 2).

[0121] An example of IAB base station connections is shown in Figure 10. IAB donor CU 901 is connected to IAB donor DU 902. IAB node 903 is connected to IAB donor DU 902 using a wireless interface. IAB node 903 is connected to IAB node 904 using a wireless interface. In other words, IAB nodes may be connected in cascade. UE 905 is connected to IAB node 904 using a wireless interface. UE 906 may be connected to IAB node 903 using a wireless interface, and UE 907 may be connected to IAB donor DU 902 using a wireless interface. Multiple IAB donor DUs 902 may be connected to an IAB donor CU 901, multiple IAB nodes 903 may be connected to an IAB donor DU 902, and multiple IAB nodes 904 may be connected to an IAB node 903.

[0122] A BAP (Backhaul Adaptation Protocol) layer is provided in the connection between the IAB donor DU and the IAB node and in the connection between the IAB nodes (see Non-Patent Document 29). The BAP layer performs operations such as routing received data to the IAB donor DU and / or the IAB node, and mapping to an RLC channel (see Non-Patent Document 29).

[0123] As an example of the configuration of the IAB donor CU, a configuration similar to that of CU 215 is used.

[0124] An example of the configuration of the IAB donor DU is the same as that of the DU 216. The protocol processing unit of the IAB donor DU performs BAP layer processing, such as adding a BAP header to downstream data, routing to an IAB node, and removing the BAP header from upstream data.

[0125] As an example of the configuration of an IAB node, a configuration excluding the EPC communication unit 401, other base station communication unit 402, and 5GC communication unit 412 shown in Figure 5 may be used.

[0126] The transmission and reception processing at the IAB node will be described using FIGS. 5 and 10 . The transmission and reception processing at the IAB node 903 in communication between the IAB donor CU 901 and the UE 905 will be described. In uplink communication from the UE 905 to the IAB donor CU 901, a radio signal from the IAB node 904 is received by the antenna 408 (some or all of the antennas 408-1 to 408-4). The received signal is converted from a radio reception frequency to a baseband signal by the frequency conversion unit 407, and demodulated by the demodulation unit 409. The demodulated data is passed to the decoder unit 410, where decoding processing such as error correction is performed. The decoded data is passed to the protocol processing unit 403, where protocol processing such as MAC and RLC used for communication with the IAB node 904 is performed, such as removing headers in each protocol. In addition, routing to the IAB donor DU 902 is performed using a BAP header, and protocol processing such as RLC and MAC used for communication with the IAB donor DU 902, such as adding headers for each protocol, is performed. The protocol-processed data is passed to the encoder unit 405, where it is subjected to encoding processing such as error correction. Some data may be output directly from the protocol processing unit 403 to the modulation unit 406 without being encoded. The encoded data is modulated by the modulation unit 406. The modulation unit 406 may also perform precoding in MIMO. The modulated data is converted into a baseband signal, and then output to the frequency conversion unit 407, where it is converted into a radio transmission frequency. Then, a transmission signal is transmitted to the IAB donor DU 902 from antennas 408-1 to 408-4. Similar processing is performed in downlink communication from the IAB donor CU 901 to the UE 905.

[0127] The IAB node 904 also performs the same transmission and reception processing as the IAB node 903. The protocol processing unit 403 of the IAB node 903 performs BAP layer processing, such as adding a BAP header and routing to the IAB node 904 in upstream communication, and removing the BAP header in downstream communication.

[0128] In 5G wireless access systems, enabling communications suitable for XR and cloud gaming services is an important issue. The characteristics of XR traffic were studied in 3GPP (see Non-Patent Document 34). Characteristics of XR traffic include, for example, non-integer periodicity, data generation time fluctuation (jitter) characteristics, data volume fluctuation characteristics, and low latency characteristics. To enable communications suitable for XR and cloud gaming services, a communication method that takes into account the characteristics of such XR traffic is required.

[0129] When an XR service is communicated in the UL, the UL data of the XR traffic is generated in the UE, and therefore the NW cannot recognize the characteristics of the UL XR traffic generated in the UE. For example, the NW cannot recognize the timing of generation of the UL data or the amount of data. Furthermore, even if the QoS of the UL XR traffic as an XR service is set in the NW, the NW cannot recognize the performance of the UL XR traffic actually transmitted from the UE. Because the NW cannot recognize the characteristics of the UL XR traffic, it cannot perform scheduling or modification appropriate for the UL XR traffic, which may result in a deterioration in communication quality.

[0130] In the first embodiment, a method for solving such a problem will be disclosed.

[0131] In this method, the UE transmits information about UL data to the gNB. Eight examples of information about UL data are disclosed: (1) data generation period; (2) data generation jitter; (3) frame rate; (4) data rate; (5) data volume; (6) packet delay budget; (7) number of streams; and (8) a combination of (1) to (7).

[0132] The UL data may be data to be transmitted 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 cycle, and data transmission jitter may be used instead of data generation jitter. In this way, information on the data that is actually transmitted can be obtained.

[0133] The information regarding UL data generated in the UE may be for each application data. The information regarding UL data generated in the UE may be for each set of data. The set of data may be a PDU set. The information regarding UL data generated in the UE may be for each PDU set. The information regarding UL data generated in the UE may be for each PDU set corresponding to the application data. For example, the information may be the generation period of the application data or the amount of application data. In this way, the gNB can obtain information regarding UL data for each application data. The gNB can set a CG suitable for the application used for communication.

[0134] Information about UL data generated by the UE may be statistical data. In this case, the UE acquires statistical data about the information about the UL data. The UE may use the acquired statistical data as information about the UL data. Examples of statistical data include the mean, median, standard deviation, variance, truncation range, maximum value, minimum value, first quartile, third quartile, mode, and number of data. The statistical data acquisition period may be statically determined by a standard, etc. For example, it may be from the start of data communication until the UE transmits the information to the gNB. As another method, the NW may notify the UE of setting information for the acquisition period. The gNB may notify the UE of the period setting information. The UE acquires statistical data according to the period setting information received from the NW. The NW can set the acquisition period, for example, according to the service status. The gNB can acquire statistical data about the information about the UL data from the UE. By using information about the UL data as statistical data, it is possible to acquire information about a large amount of UL data, or information about UL data over a long period of time. It is possible to acquire information that takes into account variations in each piece of information related to UL data.

[0135] The information about the UL data generated by the UE may be statistical data for each application data. The above methods may be combined appropriately to obtain the same effect for each application data.

[0136] The UE may notify the gNB of preference information regarding CG configuration. Preference information regarding CG configuration may include CG period, offset, time domain resource allocation, frequency domain resource allocation, etc. Combinations of these may also be used. By receiving preference information regarding CG configuration from the UE, the gNB can recognize the preferred CG configuration for the UE.

[0137] Information regarding UL data and preference information regarding CG settings may be per stream. For example, it may be per stream of XR traffic. The gNB can acquire information per stream. This information may be per QoS flow. The gNB can acquire information per stream. This information may be per bearer. The gNB can acquire information per bearer.

[0138] The gNB may use information about UL data acquired from the UE and preference information about CG settings to set CGs suitable for communication. This enables scheduling suitable for UL XR traffic, improving low latency and communication quality.

[0139] This document discloses a method for transmitting information related to UL data from a UE to a gNB and preference information related to CG configuration. RRC signaling may be used to transmit this information. New messages may be created for transmitting this information. By distinguishing this information from other information, it is possible to reduce malfunctions. Existing messages may be used to transmit this information. For example, a UE assistance information message may be used. This avoids complicating processing. By using RRC signaling, it is possible to increase the amount of information. It is also possible to improve the reliability of transmission from the UE to the gNB. It is possible to reduce malfunctions.

[0140] Other methods of transmitting this information are disclosed. MAC signaling may be used. This information may be included in a MAC CE and transmitted. A new MAC CE may be provided for transmitting this information. Distinguishing this information from other information can reduce malfunctions. An existing MAC CE may be used for transmitting this information. This can avoid complicating processing. By using MAC signaling, for example, it becomes possible to transmit from the UE to the gNB using a PUSCH configured in the CG. This simplifies the transmission process.

[0141] Other methods of transmitting this information are disclosed. PUCCH may be used. It may be transmitted by being included in UCI. New UCI may be provided for transmitting this information. By distinguishing it from other information, it is possible to reduce malfunctions. Existing UCI may be used for transmitting this information. This avoids complicating processing. Using PUCCH allows for earlier and more dynamic transmission.

[0142] This information may be transmitted from the UE to the gNB periodically or periodically. The gNB can periodically or periodically receive information about UL data in the UE and information about CG settings, allowing it to recognize the situation. Alternatively, this information may be transmitted from the UE to the gNB on a trigger basis. The UE may set conditions for transmitting this information to the gNB. The conditions may be transmitted from the gNB to the UE in advance. For example, when the standard deviation of jitter exceeds 3 ms, or when the fluctuation in the average value is 1 ms or more from the previous report. The gNB may transmit to the UE the conditions necessary to determine whether a scheduling change is necessary. In this way, the gNB can obtain this information when it needs it.

[0143] Alternatively, the information may be transmitted from the UE to the gNB on a trigger basis. The UE may set conditions for transmitting the information. The UE may set conditions for the gNB to determine whether a scheduling change is necessary. In this way, the gNB can obtain the information when the conditions set by the UE occur.

[0144] Alternatively, this information may be transmitted from the UE to the gNB on a trigger basis. An application may set conditions for transmitting this information. The application may set conditions necessary for the gNB to determine whether a scheduling change is necessary. The application may transmit the conditions to the UE, or an application server (AS) or application function (AF) may transmit the conditions to the UE. Alternatively, the application may transmit the conditions to the gNB, or an AS or AF may transmit the conditions to the gNB. In this way, the gNB can obtain this information when the conditions set by the application occur in the UE.

[0145] The gNB may request the UE to transmit information regarding UL data. The gNB may request the UE to transmit preference information regarding CG configuration. The UE receives a request to transmit the information from the gNB. When the UE receives a request to transmit the information from the gNB, it may transmit the information to the gNB. When the UE receives a request to transmit the information from the gNB, the method of transmitting the information may be the method disclosed above. The gNB may transmit information to the UE indicating which of the above-disclosed transmission methods of the information to use. This may be transmitted together with the request to transmit the information. The UE may set the transmission method according to the information received from the gNB indicating which method to use. In this way, the gNB can flexibly set the transmission method of the information to the UE and request the UE to transmit the information.

[0146] When the UE receives a transmission request for the information from the gNB, the UE may transmit the information to the gNB. For example, when the gNB needs to change the scheduling of UL data, the UE transmits a transmission request for the information to the UE. The UE transmits the information to the gNB in ​​response to the transmission request for the information received from the gNB. In this way, the gNB can transmit the information to the UE at the required timing.

[0147] A method for transmitting a request to transmit the information from a gNB to a UE is disclosed. RRC signaling may be used. A new message may be created for transmitting the request to transmit the information. Distinguishing it from other information can reduce malfunctions. An existing message may be used for transmitting the request to transmit the information. For example, an RRC Reconfiguration message may be used. This can avoid complicating processing. By using RRC signaling, it is possible to increase the amount of information. For example, it may be transmitted together with CG configuration. For example, it may be transmitted before data communication starts. It becomes possible for the UE to obtain statistical data regarding information related to UL data at an early stage.

[0148] Other methods of transmitting the transmission request for the information are disclosed. MAC signaling may be used. The information may be included in a MAC CE and transmitted. A new MAC CE may be provided for transmitting the transmission request for the information. By distinguishing it from other information, it is possible to reduce malfunctions. An existing MAC CE may be used for transmitting the transmission request for the information. This avoids complicating the processing. By using MAC signaling, early transmission is possible, and HARQ processing can reduce malfunctions.

[0149] Other methods of transmitting this information are disclosed. PDCCH may be used. This information may be included in DCI and transmitted. A new DCI may be provided for transmitting this information. Distinguishing this information from other information can reduce malfunctions. Existing DCI may be used for transmitting this information. For example, this information may be included in DCI for CG activation / deactivation and transmitted. This can avoid processing becoming complicated. Using PDCCH enables earlier and more dynamic transmission.

[0150] 11 is a diagram showing an example sequence of a method for transmitting information about UL data and preference information about CG configuration from a UE to a gNB. The processes of Steps ST3901 to ST3905 included in Step ST3910 are executed between the gNB and the UE, and information about UL data and preference information about CG configuration are transmitted from the UE to the gNB. That is, in Step ST3901, the gNB transmits a transmission request to the UE for information about UL data and preference information about CG configuration. This is transmitted using an RRCReconfiguration message. As a result, the UE performs configuration for acquiring information about UL data and configuration for deriving preference information about CG configuration. In Step ST3902, the UE transmits an RRCReconfigurationcomplete message to the gNB. It is recommended to transmit a notification of completion of the configuration requested in Step ST3901. In Step ST3903, data communication is performed between the UE and the gNB. In Step ST3904, the UE acquires information about UL data in the data communication and derives preference information about CG configuration. In Step ST3905, the UE periodically, periodically, or trigger-based transmits the acquired and derived information about UL data and preference information about CG configuration to the gNB. Whether the transmission is periodic, periodic, or trigger-based may be configured by the gNB in ​​Step ST3901, for example, and the UE may transmit the information in accordance with the configuration. In FIG. 11, RRC signaling is used to transmit the information. The information is transmitted using UEAssistanceInformation. In this way, the gNB can acquire information about UL data and preference information about CG configuration from the UE. The gNB may configure a CG suitable for communication using the information about UL data and preference information about CG configuration acquired from the UE, and may also perform scheduling suitable for UL XR traffic. This will improve low latency characteristics and communication quality.

[0151] Although FIG. 11 shows a case where both information about UL data and preference information about CG settings are transmitted, only one of them may be transmitted.

[0152] A method for transmitting information about UL data and preference information about CG configuration from a UE to a gNB has been disclosed. The information may be transmitted from the UE to a CN (Core Network). Alternatively, the information obtained from the UE may be transmitted from the gNB to the CN. The CN function may be, for example, an AMF. The UE may transmit information about UL data and preference information about CG configuration to the AMF using NAS signaling. In this way, it becomes possible to use information about UL data and preference information about CG configuration in a CN function or a CN node.

[0153] A CN function or CN node that receives information about UL data and preference information about CG settings from a UE or gNB may notify the information to an NWDAF (Network Data Analytic Function). The NWDAF can use this information. The NWDAF may use the acquired information about UL data and preference information about CG settings to perform, for example, communication control and network operation. In this way, communication control and network operation suitable for UL XR traffic are possible, improving low latency characteristics and communication quality.

[0154] The NWDAF may transmit the analysis result derived using information about UL data received from the UE or the gNB and preference information about CG settings to the application. The application may request the analysis result from the NWDAF. The NWDAF may transmit the analysis result to the application in response to the request. Although transmission and reception between the NWDAF and the application have been disclosed, the analysis result and the request may also be transmitted and received between the NWDAF and an application server (AS) or an application function (AF). The application may transmit and receive the analysis result and the request to the NWDAF via the AF or AS. In this way, the analysis result can be used in the application.

[0155] A CN function or CN node that receives information about UL data and preference information about CG configuration from a UE may notify the gNB of the information. The gNB can use this information. As disclosed above, the gNB may use information about UL data obtained from the UE and preference information about CG configuration to configure a CG suitable for communication. This enables scheduling suitable for UL XR traffic, improving low latency and communication quality.

[0156] The information may also be transmitted from the UE to an application function (AF) or application server (AS). The information obtained from the UE may also be transmitted from the gNB to the AF or AS. The gNB may also transmit the information to the AF or AS via the CN. In this way, it becomes possible for the AF or AS or application to use information regarding UL data and preference information regarding CG settings.

[0157] A method for transmitting a transmission request for the information from the gNB to the UE has been disclosed. The transmission request for the information may be transmitted from the CN to the UE. Alternatively, the transmission request for the information may be transmitted from the CN to the gNB. The gNB that receives the transmission request may request the UE to transmit the information. In this way, a CN function or a CN node can request the transmission of information related to UL data and preference information related to CG configuration.

[0158] In addition, a transmission request for the information may be sent from the AF or AS to the UE. A transmission request for the information may be sent from the AF or AS to the gNB. The AF or AS may send a transmission request for the information to the gNB via the CN. The gNB that receives the transmission request may request the UE to transmit the information. In this way, the AF or AS or an application can request the transmission of information related to UL data and preference information related to CG settings.

[0159] This section discloses DL. The gNB may transmit information about DL data and preference information about SPS (Semi Persistent Scheduling) configuration to the CN, AF, or AS. In addition, the CN, AF, or AS may transmit a transmission request for information about DL data and preference information about SPS configuration to the gNB. In this way, the AF, AS, or application can request the transmission of information about UL data and preference information about CG configuration. In this way, the CN or CN node, or the AF, AS, or application can obtain information about DL data and preference information about SPS configuration. In addition, the CN or CN node, or the AF, AS, or application can request the transmission of information about DL data and preference information about SPS configuration.

[0160] FIG. 12 is a diagram showing an example sequence of a method for transmitting information regarding UL data and DL data from a gNB to an AF. In FIG. 12, UL data and DL data are collectively referred to as XR data. In Step ST4001, data is transmitted and received between the AF, UPF, gNB, and UE. In Steps ST4002 to ST4005, the AF transmits a transmission request for information regarding XR data (XR data related information request) to the gNB via the NEF (Network Exposure Function), PCF, and AMF / SMF. The gNB that receives the transmission request for this information acquires information regarding DL data in Step ST4006. Furthermore, the gNB that receives the transmission request for this information performs the process of Step ST3910 described in FIG. 11 on the UE and acquires information regarding UL data from the UE. In steps ST4007 to ST4010, the gNB that has acquired information about DL data and information about UL data transmits information about XR data to the AF via the AMF / SMF, PCF, and NEF. In this way, the AF can acquire information about XR data from the gNB and the UE.

[0161] Although Fig. 12 discloses a case where both DL data and UL data are transmitted, only one of them may be transmitted. Although Fig. 12 discloses a case where information related to XR data is transmitted, preference information related to CG and / or SPS settings may be transmitted. A similar method may be applied as appropriate.

[0162] In this way, a CN function or a CN node, or an AF or AS or application, can obtain information regarding DL data, information regarding UL data, preference information regarding SPS settings, preference information regarding CG settings, and combinations of these.

[0163] The CN function or CN node can use the acquired information to modify the QoS and QoS flow required for the service, modify the stream, modify resource settings for communication, such as modifying network slicing settings or the UPF to be used, etc. This enables communication suitable for XR traffic and improves communication quality.

[0164] Furthermore, the AF, AS, or application can use the acquired information to modify the QoS required for the service, etc. In this way, it becomes possible to provide a service suitable for XR traffic.

[0165] Embodiment 2. A combination of multiple data may be provided (hereinafter, such a combination may be referred to as a PDU set). When a communication failure occurs for some data in a PDU set, the data of the PDU set may be discarded. This discarding may be performed by the base station. The base station may discard the data of the PDU set before transmission.

[0166] However, even if the data of a PDU set is discarded in the base station, the data of the PDU set received by the UE is not discarded and remains, resulting in a problem of data being retained in the UE.

[0167] The second embodiment discloses a method for solving the above-mentioned problems.

[0168] The method includes providing a function in the UE to discard data, the UE may discard data of a set of PDUs, or the UE may discard data of a set of PDUs that have already been received.

[0169] Both the base station and the UE may have the function of discarding data. Both the base station and the UE may discard data of a PDU set. The base station may discard PDU data before transmission. The UE may discard PDU data that has already been received.

[0170] An identifier of the PDU set may be provided. The identifier may be provided for discarding data of the PDU set. The base station may notify the UE of information about 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 may notify the identifier using an RTP (Realtime Transport Protocol) header. The RTP header may include information indicating the identifier of the PDU set. The UE may use the header to obtain information about the PDU set to be discarded. The UE may perform the obtaining operation in the PDCP layer or the IP layer. For example, the PDCP layer of the UE may obtain the information from an RTP header included in a PDCP SDU (Service Data Unit). The IP layer of the UE may obtain the information from an RTP header included in an IP payload.

[0172] As another example, the base station may notify the identifier using a GTP (GPRS Tunneling Protocol) header. The GTP header may include information indicating the identifier of the PDU set. The base station may notify the UE of information regarding the RTP header associated with the GTP header, or may notify the UE of information regarding the PDCP SN associated with the GTP header. The information regarding the RTP header may include, for example, information regarding the first RTP data, information regarding the last RTP data, information regarding the range of RTP data, or information regarding the number of RTP data. The information regarding the PDCP SN (Sequence Number) may include, for example, information regarding the first PDCP SN, information regarding the last PDCP SN, information regarding the range of PDCP SNs, or information regarding the number of PDCP SNs.

[0173] Another solution is disclosed. A timer is provided for discarding a PDU 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 in the PDU set upon expiration of the timer.

[0174] The UE may have a timer for each PDU set. This allows, for example, control by the timer for the PDU set even when data of a later PDU set is received before part of the data of an earlier PDU set. As another example, the UE may have only one timer. For example, when data of a later PDU set is received before part of the data of an earlier PDU set, the UE may start the timer for the later PDU set upon stopping or expiry of the timer for the data of the earlier PDU set. This allows, for example, to avoid complexity in controlling the timer.

[0175] The UE may share the timer among multiple PDCP entities, which may, for example, avoid complexity in control in the communication system. As another example, the UE may share the timer among multiple RLC entities, which may, for example, achieve the same effect as described above.

[0176] When the timer expires, the UE may discard data associated with the PDU set stored in the L2 layer and / or the L1 layer. The L2 layer and / or the L1 layer may be, for example, SDAP, PDCP, RLC, MAC, PHY, or a combination of the above. This may, for example, avoid complex control in the communication system.

[0177] Another solution is disclosed, in which a base station notifies a UE of a packet delay budget for a set of PDUs. The packet delay budget may be, for example, a packet delay budget for a set of downlink PDUs. The base station may notify the UE of the packet delay budget using RRC signaling, for example, RRC reconfiguration.

[0178] As another example, a core network device may notify a UE of a packet delay budget for a PDU set. The core network device may be, for example, a PCF. For example, the PCF may notify the UE of the packet delay budget. The PCF may notify the UE of the packet delay budget during, for example, a UE registration process, during a PDU session establishment process, or during a QoS policy configuration process. The core network device may be, for example, a Unified Data Management (UDM). 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 during, for example, a UE registration process, during a PDU session establishment process, or during a QoS policy configuration process.

[0179] The UE may discard the data of a PDU set if it is unable to receive all of the data of the PDU set within the packet delay budget from the first reception of the data in the PDU set.

[0180] An offset may be set in the packet delay budget of the PDU set. For example, the time required for communication from the base station to the UE may be set as the offset. In the above-described processing in the UE, a value obtained by adding the offset to the packet delay budget may be used instead of the packet delay budget. This makes it possible to prevent unnecessary discarding of data in the PDU set, even when communication from the base station to the UE takes a long time.

[0181] A timestamp may be assigned to the packet data, which the UE may use to calculate the packet delay budget. Alternatively, the UE may use the RTP timestamp to calculate the packet delay budget. This may, for example, avoid the complexity of controlling the packet delay budget in the UE. The timestamp may be assigned only to the first packet of a PDU set, which may, for example, reduce the packet size.

[0182] The method used in the second embodiment may also be used for uplink data. For example, the UE may discard data of a PDU set in the middle of transmission, and the base station may discard data of a PDU set in the middle of reception. The UE may notify the base station of information related to the PDU set. The information may be, for example, an identifier of the PDU set, a timer related to the PDU set, or a packet delay budget for the PDU set. This may provide the same effect as in the downlink.

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

[0184] The method used in the second embodiment may also be used for uplink data. For example, the UE may discard data of a PDU set in the middle of transmission, and the base station may discard data of a PDU set in the middle of reception. The UE may notify the base station of information related to the PDU set. The information may be, for example, an identifier of the PDU set, a timer related to the PDU set, or a packet delay budget for the PDU set. This may provide the same effect as in the downlink.

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

[0186] Embodiment 3. The UE notifies the base station of information regarding discarded PDU sets. The information regarding PDU sets may include, for example, information regarding the number of discarded PDU sets. The information regarding the number may be, for example, the number of discarded PDU sets within a predetermined time period, or the number of discarded PDU sets out of a predetermined number of PDU sets, or may be in units of GOP (Group of Picture), per video frame, per video stream, or per QoS flow. Information regarding the proportion of discarded PDU sets may also be included.

[0187] As another example, the information about the PDU set may include information about the number of discarded data, which may be the number of data in the PDU set, the percentage of discarded data, or the same information as the information about the number of PDU sets described above.

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

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

[0190] The information about the discarded PDU set may be acquired by the UE. As another example, the information may be acquired by the base station. For example, the information may be acquired by the CU, DU, or TRP of the base station. As another example, the information may be acquired by the core network device.

[0191] The method by which the UE transmits information about the discarded PDU set to the base station may be appropriately applied to the method of transmitting information about UL data from the UE to the base station disclosed in the first embodiment.

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

[0193] The base station may request the UE to transmit information about the discarded PDU set. This method may be implemented by appropriately applying the method disclosed in the first embodiment for requesting information about UL data from the UE to the base station.

[0194] A method for transmitting information regarding discarded PDU sets from a UE to a gNB has been disclosed. The information may be transmitted from the UE to the CN. Alternatively, the information obtained from the UE may be transmitted from the gNB to the CN. These methods may be appropriately applied to the method disclosed in the first embodiment for transmitting information regarding UL data from a UE to a CN or from a gNB to a CN.

[0195] A CN function or CN node that receives information about a discarded PDU set from a UE or a gNB may notify the NWDAF of the information. The NWDAF can use the information. The NWDAF may use the acquired information about the discarded PDU set to perform, for example, communication control or network operation. For example, the notified information may be used to perform QoS control or priority control of the PDU set. In this way, communication control and network operation suitable for services such as XR become possible, thereby improving low latency and communication quality.

[0196] The NWDAF may transmit an analysis result derived using information about the discarded PDU set received from the UE or the gNB to the application. The application may request the analysis result from the NWDAF. The NWDAF may transmit the analysis result to the application in response to the request. Although transmission and reception between the NWDAF and the application has been disclosed, the analysis result or the request may also be transmitted and received between the NWDAF and an application server (AS) or an application function (AF). The application may transmit and receive the analysis result or the request to the NWDAF via the AF or AS. In this way, the analysis result can be used in the application.

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

[0198] Alternatively, the information may be transmitted from the UE to an application function (AF) or an application server (AS). The information obtained from the UE may be transmitted from the gNB to the AF or AS. The gNB may transmit the information to the AF or AS via the CN. In this way, the AF or AS can use information regarding the PDU set discarded by the application.

[0199] A method for transmitting a transmission request for the information from the gNB to the UE has been disclosed. The transmission request for the information may be transmitted from the CN to the UE. Alternatively, the transmission request for the information may be transmitted from the CN to the gNB. The gNB that receives the transmission request may request the UE to transmit the information. In this way, a CN function or a CN node can request the transmission of information regarding the discarded PDU set.

[0200] Alternatively, the AF or AS may send a transmission request for the information to the UE. The AF or AS may send a transmission request for the information to the gNB. The AF or AS may send a transmission request for the information to the gNB via the CN. The gNB that receives the transmission request may request the UE to transmit the information. In this way, it is possible for the AF or AS or application to request the transmission of information regarding the discarded PDU set.

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

[0202] Fourth Embodiment When UE mobility occurs, downlink data is transferred from the source base station to the destination base station. As a result, data may be transferred from a packet in the middle of a PDU set. However, the destination base station does not recognize the timing when the source base station transmits the first data in the PDU set. Alternatively, the destination base station does not recognize the timing when the source base station receives the first data in the PDU set from the UPF. For this reason, the destination base station cannot determine whether all data in the PDU set has been transmitted within the packet delay budget. As a result, for example, the destination base station cannot perform priority control, scheduling control, and / or data discard control. This causes problems.

[0203] The fourth embodiment discloses a method for solving the above-mentioned problems.

[0204] That is, in the method shown in the fourth embodiment, the source base station notifies the destination base station of information related to the timing of the first data transmission in the PDU set including the data to be transferred. The source base station may also notify the destination base station of information related to the timing of receiving the first data in the PDU set from the UPF. The above-mentioned method may be applied, for example, to downlink communication.

[0205] Information about the first data in the PDU set may be provided. The source base station may use Xn signaling as a method for notifying the target base station of the information. The information may be included in, for example, SN status transfer signaling or early status transfer signaling.

[0206] The source base station may use a user plane protocol used in NG-RAN as a method of notifying the destination base station of the information, which makes it possible to process the information as user plane data.

[0207] The above method may be applied to uplink communication, for example, the source base station notifies the destination base station of information regarding the timing of first data reception in a PDU set.

[0208] This fourth embodiment enables the destination base station to determine whether all data in a PDU set has been transmitted within the packet delay budget, thereby enabling, for example, the destination base station to perform priority control, scheduling control, and / or data discard control.

[0209] Although the above has been disclosed regarding the occurrence of UE mobility, it may also be applied as appropriate to DC (Dual Connectivity). For example, it may be applied as appropriate to an SCG addition process. It may also be applied as appropriate to a transition process from an MN terminated bearer to an SN terminated bearer, or from an SN terminated bearer to an MN terminated bearer. Even in DC, the base station can perform priority control, scheduling control, and / or data discard control.

[0210] Fifth embodiment Priorities may be assigned to PDU sets Scheduling may be performed using priorities assigned to PDU sets.

[0211] For example, in SPS, when the transmission timings of some of the data of multiple PDU sets collide, the base station may transmit the data of the PDU set with the highest priority.

[0212] As another example, in a CG, when the transmission timings of some of the data of multiple PDU sets collide, the UE may transmit the data of a PDU set with a higher priority.

[0213] For example, if a PDU set is discarded because some of the data in the PDU set cannot be delivered and the packet delay budget is exceeded, prioritizing other data in the PDU set would be pointless. To solve this problem, a priority may be assigned to each PDU set. For example, instead of prioritizing other data in the discarded PDU set, control may be performed to prioritize scheduling other PDU sets. In this way, resources allocated to other data in the PDU set can be allocated to data in other PDU sets.

[0214] By performing priority control for each PDU set in this way, efficient priority control becomes possible, and the efficiency of use of radio resources can be improved.

[0215] In this disclosure, it is described as a gNB or a cell, but unless otherwise specified, it may be a gNB or a cell.

[0216] In the present disclosure, a gNB may be an MCG or an SCG.

[0217] The above-described embodiments and their modifications are merely examples, and the embodiments and their modifications can be freely combined. Furthermore, any of the components of the embodiments and their modifications can be modified or omitted as appropriate.

[0218] For example, in the above-described embodiments and their modifications, a slot is an example of a time unit for communication in a fifth-generation communication system. A slot may be a scheduling unit. In the above-described embodiments and their modifications, processing described as being performed in slot units may be performed in TTI units, subframe units, subslot units, or minislot units.

[0219] For example, the methods disclosed in the above-described embodiments and their modifications may be applied to the IAB, to communication between an IAB donor and an IAB node, or to processing using a Uu in the IAB.

[0220] For example, the methods disclosed in the above-described embodiments and their modifications may be applied to SL communication, for example, communication between a UE and a NW via a relay, or communication between a UE and a NW by an L2 relay.

[0221] For example, the methods disclosed in the above-described embodiments and their modified examples may be applied to services that use SL communication, not limited to V2X (Vehicle-to-everything) services, such as proximity-based services, public safety, communication between wearable devices, and communication between devices in factories.

[0222] Various aspects of the present disclosure are summarized below as appendices.

[0223] (Supplementary Note 1) A communication system comprising: a base station compatible with 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, wherein when the communication terminal uses the XR service via the base station, the communication terminal notifies the base station of information regarding characteristics of uplink data to be transmitted to the base station in communication for using the XR service. (Supplementary Note 2) The communication system according to Supplementary Note 1, wherein the base station schedules transmission of the uplink data by the communication terminal based on information regarding the uplink data acquired from the communication terminal. (Supplementary Note 3) The communication system according to Supplementary Note 1 or 2, wherein the communication system is configured to be able to combine multiple data of predetermined units and perform transmission processing as a data set, and wherein, when transmission of at least one data set included in the data set fails, at least one of the base station and the communication terminal discards the data whose transmission failed and other data in the data set including the data whose transmission failed from a transmission buffer. (Supplementary Note 4) The communication system according to Supplementary Note 3, wherein, when at least one of the base station and the communication terminal fails to receive at least one data set included in the data set, the received data is discarded from the receive buffer, and the data is included in the same data set as the data that the reception failed to. (Supplementary Note 5) The communication system according to Supplementary Note 3 or 4, wherein, when the communication terminal discards data from the transmit buffer due to a data transmission failure, and when the communication terminal discards data from the receive buffer due to a data reception failure, the communication terminal notifies the base station of information regarding the data set including the discarded data.(Supplementary Note 6) The communication system according to any one of Supplementary Notes 3 to 5, comprising: a plurality of the base stations; and when a communication terminal connected to a first base station that is one of the plurality of base stations switches its connection destination to a second base station that is also one of the plurality of base stations and different from the first base station, the first base station starts transferring data addressed to the communication terminal that is switching its connection destination to the second base station, and when the data to be transferred to the second base station includes data included in the same data set as data that has already been transmitted to the communication terminal that is switching its connection destination, notifies the second base station of information related to the transmission timing of first data included in the same data set as the data to be transferred to the second base station. (Supplementary Note 7) The communication system according to any one of Supplementary Notes 3 to 6, comprising: a priority order set for the data sets; and the base station schedules data transmission to the communication terminal based on the priority order.

[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 plane, 218 Central unit for user plane, 219 TRP, 301, 403 Protocol processing unit, 302 Application unit, 304, 405 Encoder unit, 305, 406 Modulation unit, 306, 407 Frequency conversion unit, 307-1 to 307-4, 408-1 to 408-4 Antenna, 308, 409 Demodulation unit, 309, 410 Decoder unit, 310, 411, 526 Control unit, 401 EPC communication unit, 402 Other base station communication unit, 412 5GC communication unit, 521 Data Network communication unit, 522 base station communication unit, 523 user plane communication unit, 523-1 PDU processing unit, 523-2 mobility anchoring unit, 525 control plane control unit, 525-1 NAS security unit, 525-2 idle state mobility management unit, 527 session management unit, 527-1 PDU session control unit, 527-2 UE IP address allocation unit, 751-1 to 751-8 beams, 752 cell.

Claims

1. A communication system comprising: a base station that is compatible with a fifth-generation wireless access system and is connected to a core network that can provide the XR service; and a communication terminal that connects to the base station, wherein when the communication terminal uses the XR service via the base station, the communication terminal notifies the base station of information regarding the characteristics of uplink data that is transmitted to the base station in communication for using the XR service.

2. The communication system according to claim 1, wherein the base station schedules transmission of the uplink data by the communication terminal based on information relating to the uplink data acquired from the communication terminal.

3. The communication system according to claim 1, characterized in that it is configured to be able to combine multiple data of a predetermined unit and perform transmission processing as a data set, and when transmission of at least one of the base station and the communication terminal fails, it discards from a transmission buffer the data that failed to be transmitted and other data in the data set that includes the data that failed to be transmitted.

4. The communication system according to claim 3, wherein, when at least one of the base station and the communication terminal fails to receive at least one data item included in the data set, the received data that is included in the same data set as the data that failed to be received is discarded from the receive buffer.

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

6. The communication system according to claim 3, further comprising a plurality of the base stations, wherein when a communication terminal connected to a first base station that is one of the plurality of base stations switches its connection destination to a second base station that is also one of the plurality of base stations and different from the first base station, the first base station starts transferring data addressed to the communication terminal that is switching its connection destination to the second base station, and if the data to be transferred to the second base station contains data included in the same data set as data that has already been transmitted to the communication terminal that is switching its connection destination, the first base station notifies the second base station of information regarding the transmission timing of the first data included in the same data set as the data to be transferred to the second base station.

7. The communication system according to claim 3, wherein priorities are set for the data sets, and the base station schedules data transmission to the communication terminal based on the priorities.

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