Communication control method, network node, mobile communication system, program and chipset

Abstract

This invention provides a communication control method, network node, mobile communication system, program, and chipset for a mobile communication system that supports assistance information related to XR (eXtended Reality). [Solution] A communication control method in a mobile communication system includes: a user device transmitting assist information relating to XR, which includes timing information indicating the timing at which the user device receives a packet, to a first network node; the first network node performing a handover for the user device to a second network node; and the first network node transmitting timing information to the second network node when performing the handover.

Description

Technical Field

[0001] The present disclosure relates to a communication control method, a network node, a mobile communication system, a program, and a chipset in a mobile communication system.

Background Art

[0002] In the specifications of 3GPP (The Third Generation Partnership Project) (registered trademark; the same applies hereinafter), which is a standardization project for mobile communication systems, XR (Extended Reality) has been approved for Release 18. XR includes virtual reality (VR: Virtual Reality), augmented reality (AR: Augmented Reality), and mixed reality (MR: Mixed Reality), and is a broad term representing an environment that fuses the real world and the virtual space. XR represents a composite environment of the real space and the virtual space generated by computer technology and wearable devices, and represents the interaction between humans and machines.

Prior Art Documents

Non-Patent Documents

[0003]

Non-Patent Document 1

Non-Patent Document 2

Summary of the Invention

[0004] One embodiment of the communication control method is a communication control method in a mobile communication system. The communication control method includes a step in which a user device transmits XR (eXtended Reality) related XR assist information to a base station. Here, XR includes virtual reality (VR), augmented reality (AR), and mixed reality (MR), and represents an environment that fuses the real world and virtual space.

[0005] Furthermore, one embodiment of the communication control method is a communication control method in a mobile communication system. The communication control method includes a step in which an access mobility management device transmits XR assist information relating to XR to a base station. Here, XR includes virtual reality, augmented reality, and mixed reality, and represents an environment that merges the real world and virtual space. [Brief explanation of the drawing]

[0006] [Figure 1] Figure 1 is a diagram showing an example configuration of a mobile communication system according to the first embodiment. [Figure 2] Figure 2 is a diagram showing an example configuration of a UE (User Equipment) according to the first embodiment. [Figure 3] Figure 3 is a diagram showing an example configuration of a gNB (base station) according to the first embodiment. [Figure 4] Figure 4 is a diagram showing an example of the configuration of a protocol stack related to the user plane according to the first embodiment. [Figure 5] Figure 5 is a diagram showing an example of the configuration of a protocol stack related to the control plane according to the first embodiment. [Figure 6] Figure 6 is a diagram illustrating an example of operation according to the first embodiment. [Figure 7] Figure 7 is a diagram showing an example of operation according to Modification 1 of the First Embodiment. [Figure 8] Figure 8 is a diagram showing an example of operation according to Modification 2 of the First Embodiment. [Figure 9] Figure 9 is a diagram showing an example of operation according to Modification 3 of the First Embodiment. [Figure 10] Figure 10 is a diagram illustrating an example of operation according to the second embodiment. [Figure 11] Figure 11 is a diagram illustrating an example of operation according to the third embodiment. [Modes for carrying out the invention]

[0007] One aspect of this disclosure aims to provide a communication control method that enables communication using XR to be performed appropriately.

[0008] A mobile communication system according to an embodiment will be described with reference to the drawings. In the drawings, identical or similar parts are denoted by the same or similar reference numerals.

[0009] [First Embodiment] (Configuration of mobile communication systems) Figure 1 is a diagram showing the configuration of a mobile communication system according to the first embodiment. The mobile communication system 1 conforms to the 5th Generation System (5GS) of the 3GPP standard. In the following explanation, 5GS will be used as an example, but the mobile communication system may also have at least a portion of an LTE (Long Term Evolution) system applied to it. Alternatively, the mobile communication system may also have at least a portion of a 6th Generation (6G) system applied to it.

[0010] The mobile communication system 1 comprises User Equipment (UE) 100, a 5G radio access network (NG-RAN) 10, and a 5G core network (5GC) 20. Hereafter, NG-RAN 10 may be simply referred to as RAN 10, and 5GC 20 may be simply referred to as core network (CN) 20.

[0011] A UE100 is a mobile wireless communication device. A UE100 can be any device used by a user. For example, a UE100 can be a mobile phone terminal (including a smartphone), a tablet terminal, a notebook PC, a communication module (including a communication card or chipset), a sensor or a device attached to a sensor, a vehicle or a device attached to a vehicle (Vehicle UE), or an aircraft or a device attached to an aircraft (Aerial UE).

[0012] UE100 includes XR devices. An XR device is, for example, a device capable of XR processing. Specifically, XR devices include head-mounted displays (HMDs) that can be worn on a person's head, AR glasses (or smart glasses), handheld mobile devices, smartwatches, or smartphones. These XR devices may also be called wearable devices. HMDs include a display, lenses, tracking sensors, cameras, a control unit that performs XR-related processing (such as a CPU (Central Processing Unit) or GPU (Graphics Processing Unit)), and communication functions. AR glasses have the ability to transmit images. Mobile handsets may include various sensors such as tracking sensors. HMDs, AR glasses, smartwatches, and mobile handsets have communication functions that support 5G systems, etc. In the following description, UE100 will be described assuming that it includes such XR devices.

[0013] NG-RAN 10 includes base stations (referred to as "gNB" in the 5G system) 200. The gNBs 200 are interconnected via the Xn interface, which is an interface between base stations. The gNB 200 manages one or more cells. The gNB 200 performs wireless communication with the UE 100 that has established a connection with its cell. The gNB 200 has functions such as a radio resource management (RRM) function, a routing function for user data (hereinafter simply referred to as "data"), and a measurement control function for mobility control and scheduling. A "cell" is a term used to indicate the smallest unit of a wireless communication area. A "cell" is also used as a term to indicate a function or resource for performing wireless communication with the UE 100. One cell belongs to one carrier frequency (hereinafter simply referred to as "frequency").

[0014] Note that the gNB can also be connected to the EPC (Evolved Packet Core), which is the core network of LTE. The base station of LTE can also be connected to the 5GC. The base station of LTE and the gNB can also be connected via an interface between base stations.

[0015] The 5GC 20 includes an AMF (Access and Mobility Management Function) and a UPF (User Plane Function) 300. The AMF performs various mobility controls for the UE 100. The AMF manages the mobility of the UE 100 by communicating with the UE 100 using NAS (Non-Access Stratum) signaling. The UPF performs transfer control of data. The AMF and the UPF are connected to the gNB 200 via the NG interface, which is an interface between the base station and the core network.

[0016] FIG. 2 is a diagram showing the configuration of the UE 100 (user equipment) according to the first embodiment. The UE 100 includes a receiving unit 110, a transmitting unit 120, and a control unit 130. The receiving unit 110 and the transmitting unit 120 constitute a wireless communication unit that performs wireless communication with the gNB 200.

[0017] The receiving unit 110 performs various receptions under the control of the control unit 130. The receiving unit 110 includes an antenna and a receiver. The receiver converts the radio signal received by the antenna into a baseband signal (received signal) and outputs it to the control unit 130.

[0018] The transmitting unit 120 performs various transmissions under the control of the control unit 130. The transmitting unit 120 includes an antenna and a transmitter. The transmitter converts the baseband signal (transmission signal) output by the control unit 130 into a radio signal and transmits it from the antenna.

[0019] The control unit 130 performs various controls and processes in the UE 100. Such processes include the processes of each layer described later. The control unit 130 includes at least one processor and at least one memory. The memory stores programs executed by the processor and information used for the processing by the processor. The processor may include a baseband processor and a CPU (Central Processing Unit). The baseband processor performs modulation / demodulation and encoding / decoding of the baseband signal. The CPU executes programs stored in the memory to perform various processes. Note that the control unit 130 may perform each process or each operation in the UE 100 in each of the embodiments shown below.

[0020] FIG. 3 is a diagram showing the configuration of the gNB 200 (base station) according to the first embodiment. The gNB 200 includes a transmitting unit 210, a receiving unit 220, a control unit 230, and a backhaul communication unit 240. The transmitting unit 210 and the receiving unit 220 constitute a radio communication unit that performs radio communication with the UE 100. The backhaul communication unit 240 constitutes a network communication unit that communicates with the CN 20.

[0021] The transmitting unit 210 performs various transmissions under the control of the control unit 230. The transmitting unit 210 includes an antenna and a transmitter. The transmitter converts the baseband signal (transmission signal) output by the control unit 230 into a radio signal and transmits it from the antenna.

[0022] The receiving unit 220 performs various types of reception under the control of the control unit 230. The receiving unit 220 includes an antenna and a receiver. The receiver converts the radio signal received by the antenna into a baseband signal (received signal) and outputs it to the control unit 230.

[0023] The control unit 230 performs various control and processing in the gNB200. Such processing includes processing in each layer described later. The control unit 230 includes at least one processor and at least one memory. The memory stores programs executed by the processor and information used for processing by the processor. The processor may include a baseband processor and a CPU. The baseband processor performs modulation, demodulation, encoding, decoding, etc., of the baseband signal. The CPU executes programs stored in memory and performs various processing. In each of the embodiments shown below, the control unit 230 may perform each processing or operation in the gNB200.

[0024] The backhaul communication unit 240 is connected to an adjacent base station via the Xn interface, which is an inter-base station interface. The backhaul communication unit 240 is connected to the AMF / UPF300 via the NG interface, which is an inter-base station-core network interface. The gNB200 may consist of a CU (Central Unit) and a DU (Distributed Unit) (i.e., functionally separated), and the two units may be connected by the F1 interface, which is a fronthaul interface.

[0025] Figure 4 shows the configuration of the protocol stack for the user plane's wireless interface that handles data.

[0026] The user plane radio interface protocol consists of a physical (PHY) layer, a MAC (Medium Access Control) layer, an RLC (Radio Link Control) layer, a PDCP (Packet Data Convergence Protocol) layer, and an SDAP (Service Data Adaptation Protocol) layer.

[0027] The PHY layer performs encoding / decoding, modulation / demodulation, antenna mapping / demapping, and resource mapping / demapping. Data and control information are transmitted between the UE100's PHY layer and the gNB200's PHY layer via a physical channel. The UE100's PHY layer receives downlink control information (DCI) transmitted from the gNB200 over the physical downlink control channel (PDCCH). Specifically, the UE100 performs blind decoding of the PDCCH using a Radio Network Temporary Identifier (RNTI) and acquires the successfully decoded DCI as the DCI addressed to its own UE. The DCI transmitted from the gNB200 has a CRC parity bit added, which is scrambled by the RNTI.

[0028] The MAC layer performs data priority control, retransmission processing using Hybrid Automatic Repeat request (HARQ), and random access procedures. Data and control information are transmitted between the MAC layer of the UE100 and the MAC layer of the gNB200 via the transport channel. The MAC layer of the gNB200 includes a scheduler. The scheduler determines the transport format for the up and down links (transport block size, modulation and coding scheme (MCS)) and the resource blocks to be allocated to the UE100.

[0029] The RLC layer transmits data to the receiving RLC layer using the functions of the MAC layer and PHY layer. Data and control information are transmitted between the UE100's RLC layer and the gNB200's RLC layer via a logical channel.

[0030] The PDCP layer performs header compression / decompression, encryption / decryption, etc.

[0031] The SDAP layer maps IP flows, which are the units under which the core network performs QoS (Quality of Service) control, to wireless bearers, which are the units under which the AS (Access Stratum) performs QoS control. Note that if the RAN is connected to the EPC, the SDAP is not required.

[0032] Figure 5 shows the configuration of the protocol stack of the wireless interface of the control plane that handles signaling (control signals).

[0033] The control plane's wireless interface protocol stack includes an RRC (Radio Resource Control) layer and a NAS (Non-Access Stratum) layer, instead of the SDAP layer shown in Figure 4.

[0034] RRC signaling for various settings is transmitted between the RRC layer of the UE100 and the RRC layer of the gNB200. The RRC layer controls the logical channel, transport channel, and physical channel in response to the establishment, re-establishment, and release of the radio bearer. If there is a connection (RRC connection) between the RRC of the UE100 and the RRC of the gNB200, the UE100 is in the RRC connected state. If there is no connection (RRC connection) between the RRC of the UE100 and the RRC of the gNB200, the UE100 is in the RRC idle state. If the connection between the RRC of the UE100 and the RRC of the gNB200 is suspended, the UE100 is in the RRC inactive state.

[0035] The NAS, located above the RRC layer, handles session management and mobility management, among other things. NAS signaling is transmitted between the UE100's NAS and the AMF300's NAS. The UE100 also has application layers in addition to the wireless interface protocol. Layers below the NAS are called AS (Access Stratum).

[0036] (About XR) As mentioned above, XR is a broad term that encompasses virtual reality (VR), augmented reality (AR), and mixed reality (MR), representing environments that merge the real world and virtual space. XR is also a general term for various types of realities. Furthermore, XR is a general term for technologies that enable us to perceive things that do not exist in reality by merging the real world and virtual space.

[0037] In XR, human-to-machine and human-to-human communication is performed with the support of the UE100, which is a portable or wearable end-user device. This type of communication makes it possible to apply XR to various application areas such as entertainment, healthcare, and education.

[0038] Along with XR, one of the use cases for future mobile systems is cloud gaming (CG). Cloud gaming is a general term for use cases where, for example, most of the calculations related to games are offloaded to edge servers or remote servers. In cloud gaming, the UE100 transmits information related to pose and / or control. On the cloud side, calculations related to video data, etc., are performed based on this information, and game-related video and other content are provided to the UE100.

[0039] Virtual reality (VR) refers to the creation of an environment that is not the original (or real world) but whose functional essence is the same as the original, by stimulating the user's senses. In virtual reality (VR), the user typically wears an HMD (head-mounted display), their field of view is replaced with simulated visual elements, and accompanying sounds are provided to the user through headphones. The virtual space is designed to mimic sensory stimuli such as sight or hearing from the real world as naturally as possible. The metaverse, which is a virtual space (or service) built within a computer or computer network and is different from the real world, can also be included in virtual reality (VR).

[0040] Augmented reality (AR) is a technology that, for example, overlays a virtual space onto the real world. In augmented reality (AR), additional information (artificially generated items or content) is overlaid on the user's real environment. This additional information can be perceived directly without the need for sensors, or indirectly through sensors.

[0041] Furthermore, mixed reality (MR) is a technology that, for example, combines and / or merges the real world and virtual space to create a space where they interact with each other in real time. Mixed reality (MR) is an evolution of augmented reality (AR) and is designed to insert virtual elements into a physical scene, creating the illusion that they are part of the actual scene.

[0042] While virtual reality (VR), augmented reality (AR), and mixed reality (MR) are typical forms of XR, areas that bridge the gap between these can also be included in XR.

[0043] Many use cases for XR and cloud gaming (CG) are characterized by video stream traffic in the DL direction and a combination of pose and / or control data and video stream traffic in the UL direction. Video streams have a higher data rate compared to others, and pose and / or control data is updated frequently. Furthermore, XR and cloud gaming (CG) are characterized by latency-sensitive traffic in both the DL and UL directions compared to other use cases.

[0044] (XR traffic model) The following describes XR traffic models. XR traffic models include (1) general traffic models and (2) specific traffic models. First, we will explain (1) general traffic models. (1) General traffic models include (1.1) DL direction traffic models and (1.2) UL direction traffic models.

[0045] (1) General traffic model

[0046] (1.1) DL-direction traffic model There are two types of DL (Download) traffic models: single-stream DL traffic models and multi-stream DL traffic models. These two traffic models can be summarized as follows:

[0047] (1.1.1) Single-stream DL traffic model: A series of video frames

[0048] (1.1.2) Multistream DL traffic model:

[0049] (1.1.2.1) Option #1: Two streams, where the first stream is an I (Intra-coded) stream and the second stream is a P (Predicted) stream. Option #1 has two traffic models: a slice-based traffic model (Option #1A) and a GOP (Group-Of-Picture)-based traffic model (Option #1B).

[0050] (1.1.2.1A) Option #1A (Slice-based): The first stream becomes an I-slice (I-stream), and the second stream becomes a P-slice (P-stream). Here, an I-slice is, for example, a slice in which all macroblocks contained within the I-slice are encoded by intra-frame prediction. A P-slice is, for example, a slice in which all macroblocks contained within the P-slice are encoded by intra-frame prediction or inter-frame prediction. If a video frame is sliced ​​into N parts, one may become an I-slice, and the remaining (N-1) may become P-slices.

[0051] (1.1.2.1B) Option #1B (GOP-based): The first stream is an I-frame (I-stream), and the second stream is a P-slice (P-stream). Here, an I-frame is a frame encoded using that video frame without using other video frames. A P-frame is a frame encoded using video frames in the temporally preceding direction. If the size of the GOP is K frames, an I-frame is sent every K frames. The GOP contains one I-frame and (K-1) P-frames.

[0052] (1.1.2.2) Option #2: A traffic model with two streams, where the first stream is video and the second stream is audio and / or data.

[0053] (1.1.2.3) Option #3: A traffic model in which the first stream is FOV (Field of View) and the second stream is omnidirectional view. For example, FOV is video data from the user's perspective, and omnidirectional view is video data from all directions centered on the user, including video data from the user's perspective.

[0054] (1.2) Traffic model in the UL direction One traffic model in the UL direction is the attitude and / or control stream traffic model. This is the traffic model in which UE100 transmits attitude and / or control-related data.

[0055] (2) Specific traffic model Specific traffic models include (2.1) virtual reality (VR), (2.2) augmented reality (AR), and (2.3) computer gaming (CG).

[0056] (2.1) Virtual reality (VR) traffic models The traffic model for virtual reality (VR) can be summarized as follows:

[0057] (2.1.1) DL Stream: Single-stream model: Same as (1.1.1) "Single-stream DL traffic model" (a series of video frames) above. Multi-stream model: Same as above (1.1.2.2) "Option #2" (first stream is video, second stream is audio and / or data).

[0058] (2.1.2) UL Stream: Same as (1.2) "Traffic Model in the UL Direction" above.

[0059] (2.2) Traffic models for augmented reality (AR) The traffic model for augmented reality (AR) can be summarized as follows:

[0060] (2.2.1) DL Stream: Same as above (2.1.1)

[0061] (2.2.2) UL Stream: Model #1: 1-Stream Model Model #2: Two-stream model: The first stream contains attitude and / or control data, while the second stream combines the scene (e.g., a sequence of images), video, data, and audio. Model #3A: 3-Stream Model A: The first stream is for attitude and / or control, the second stream is a single stream combining the scene stream and the video stream, and the third stream is a single stream combining audio and data. Model #3B: 3-stream Model B: The first stream is attitude and / or control, the second stream is the I stream of video, and the third stream is the P stream of video.

[0062] (2.3) Computer Gaming (CG) Traffic Models The traffic model for computer gaming (CG) can be summarized as follows:

[0063] (2.3.1) DL Stream Single-stream model: Same as (1.1.1) "Single-stream DL traffic model" (a series of video frames) above. Multistream model: Same as (1.1.2) "Multistream DL traffic model" above.

[0064] (2.3.2) UL Stream: Same as (1.2) "Traffic Model in the UL Direction" above.

[0065] (Communication control method according to the first embodiment) In the first embodiment, the objective is to ensure that communication using XR is performed appropriately in the mobile communication system 1, taking into account the characteristics of XR traffic.

[0066] Therefore, the user device (e.g., UE100) transmits XR-related XR assist information to the base station (e.g., gNB200). Here, XR includes virtual reality (VR), augmented reality (AR), and mixed reality (MR), representing an environment that merges the real world and virtual space.

[0067] Since XR assist information is transmitted to gNB200, gNB200 can make appropriate settings for XR-based communication to UE100 based on the XR assist information. Therefore, the mobile communication system 1 can properly perform XR-based communication through such settings.

[0068] Here, the XR assist information includes traffic information relating to the traffic characteristics of the XR traffic. In the first embodiment, an example in which the XR assist information includes traffic information will be described.

[0069] (Example of operation according to the first embodiment) Figure 6 is a diagram illustrating an example of operation according to the first embodiment.

[0070] As shown in Figure 6, in step S10, the AS of UE100 receives traffic information from a higher layer (e.g., the application layer or the NAS layer).

[0071] In step S11, UE100 sends XR assist information, including traffic information, to gNB200. XR assist information is assistance information related to XR. XR assist information may also be information that UE100 expects gNB200 to make optimal settings for XR communication by sending this information to gNB200. Prior to step S11, gNB200 may request UE100 to notify gNB200 of the XR assist information. This request may be sent, for example, in an RRC message or MAC CE.

[0072] UE100 may include XR assist information in an RRC message and send it to gNB200. In this case, UE100 may send the XR assist information as UE Assistance Information. Alternatively, UE100 may send the XR assist information as a new message (e.g., XR Assistance Information). Furthermore, UE100 may include the XR assist information in a MAC CE instead of an RRC message, or in a PDCP Control PDU (Protocol Data Unit). In addition, if there is a Control PDU dedicated to the XR layer, UE100 may include the XR assist information in that PDU and send it.

[0073] Traffic information included in XR Assist information includes, for example, the following:

[0074] Firstly, traffic information may be a Logical Channel Identifier (LCID) used to transmit XR traffic. Traffic information may also be the Bearer ID of a Bearer used to transmit XR traffic. Alternatively, the traffic information may be the RLC Channel ID of an RLC channel used to transmit XR traffic. Traffic information may be represented by an RNTI (Radio Network Temporary Identifier). For example, the CS-RNTI (Configured Scheduling Radio Network Temporary Identifier) ​​used when transmitting XR traffic using CS (Configured Scheduling) may be the traffic information. CS (Configured Scheduling) is a scheduling method that, once a radio resource is allocated to the UL direction, periodically uses that radio resource to enable transmission in the UL direction. Also, for example, if there is an RNTI dedicated to XR, that RNTI may be the traffic information. If there is an XR session ID, the traffic information may be the XR session ID. In other words, traffic information may be identification information related to the transmission path through which XR traffic is transmitted.

[0075] Secondly, traffic information may be the throughput of XR traffic. Traffic information may also be the number of bits transmitted per burst. In this case, the number of bits transmitted may be the transport block size. Traffic information may also be the throughput per burst. Traffic information may also be the average throughput.

[0076] Thirdly, the traffic information may also be the Packet Delay Budget (PDB). Note that the PDB is a Quality of Service (QoS) parameter that represents the upper limit of packet delay between the UE100 and the UPF.

[0077] Fourth, traffic information may also be a traffic pattern. Specifically, a traffic pattern may be a transmission cycle and / or reception cycle. The transmission cycle and / or reception cycle may represent the duration of one burst or the interval between bursts. A traffic pattern may also be expressed in terms of the video frame generation rate (fps (frames per second) or Hz).

[0078] Fifth, the traffic information may also be an identifier indicating the transmission direction of the XR traffic (UL direction or DL ​​direction). This takes into account that the traffic patterns of XR traffic may differ between the UL direction and the DL direction. The UE100 may transmit traffic information for the UL direction and traffic information for the DL direction. For example, the throughput in the UL direction may be XX and the latency tolerance may be YY, while the throughput in the DL direction may be ZZ and the latency tolerance may be UU.

[0079] Sixth, traffic information may be represented by a QoS value. This QoS value may represent the base characteristics of the XR traffic. The base characteristics may be represented by 5QI. For example, if the QoS value of the traffic information is represented by "5" in 5QI, then the QoS represented by "5" in 5QI can be the base characteristics of the XR traffic. This QoS value can also be combined with the latency tolerance described above. For example, if the QoS value is represented by "5" in 5QI and the latency tolerance is represented by 2ms, then it can be expressed as XR traffic with a base characteristic of "5" in 5QI and a latency tolerance of 2ms.

[0080] Seventh, traffic information may also be the time difference between the assigned CG (Configured Grant) setting and the actual arrival time of the packet. Specifically, the traffic information may be the difference between the transmission start timing in the CG set by the CG setting (or the start timing of the DRX active time, which represents the time the UE100 monitors the PDCCH) and the timing when the packet is actually received from the upper layer in the UE100's AS. Alternatively, the traffic information may be the difference between the transmission start timing in the CG and the timing when the packet from the upper layer becomes ready for transmission (for example, the PDCP processing completion timing). In the UE100, the smaller such difference, the lower the latency of transmission becomes possible.

[0081] Eighth, when multi-stream transmission is performed in XR traffic, the XR assist information may include traffic information for each stream. In the XR traffic model described above, multi-streams included two-stream transmission using I-streams and P-streams (as described in (1.1.2.1) above). The XR assist information may include traffic information for the I-stream, traffic information for the P-stream, etc. In this case, the traffic information for each stream may be represented in list form in the XR assist information. The number of streams may be implicitly represented by the number of entries in the list. Information representing the association between streams may be included in the XR assist information. For example, if two streams are used as an XR session, the information may represent that the two streams are linked to one XR session. If each stream in a multi-stream is associated with each QoS flow ID, each bearer ID, or each LCID, the XR assist information may include information representing the association between each QoS flow ID, each bearer ID, or each LCID.

[0082] In step S12, the gNB200 configures the UE100 based on the XR assist information. For example, the gNB200 configures the C-DRX (Connected mode-Discontinuous Reception) setting (or SPS (Semi-Persistent Scheduling) setting) in the DL direction and the CG setting in the UL direction. C-DRX is a technology that allows the UE100 to operate intermittently while maintaining the RRC connected state. SPS is a scheduling method that, once a wireless resource is allocated in the DL direction, periodically enables transmission in the DL direction using that resource. Here, the gNB200 may perform scheduling based on the XR assist information. In addition to SPS or CG, this scheduling may also be dynamic scheduling (for example, allocation of wireless resources for each PDSCH).

[0083] In step S13, gNB200 sends configuration information to UE100. gNB200 may include the configuration information in an RRC message, such as an RRCSetup message, and send it. Alternatively, gNB200 may include the configuration information in a dedicated RRC message and send it. gNB200 may also include the configuration information in a MAC CE or DCI and send it. If gNB200 was unable to configure UE100 in step S12, it may send an error notification to UE100 in step S13. gNB200 may send an RRC message, MAC CE, or DCI, similar to the configuration information, including the error notification. The error notification may include time information during which the configuration information is available (or can be sent). The time information may be expressed as elapsed time from the current time (e.g., 3 hours later). Alternatively, the time information may be expressed as time information (e.g., 24:00).

[0084] In step S14, UE100 applies the configuration information. Based on this configuration information, the AS of UE100 may output transmission timing and / or reception timing information for XR-related communications to the upper layer (e.g., the application layer). The upper layer may appropriately adjust the resolution or bitrate of the XR application according to this configuration information.

[0085] (Modification 1 of the first embodiment) As described in the first embodiment, there are various types of XR traffic models. For example, in an augmented reality (AR) UL stream, the first stream is for attitude and / or control, the second stream is a single stream combining the scene stream and the video stream, and the third stream is a single stream combining audio and data (Model #3A). As described in Non-Patent Literature 2, different performance requirements exist for each type.

[0086] Modification 1 of the first embodiment describes an example in which the information included in the XR assist information includes information about the type of XR traffic. Specifically, the information about the type of XR traffic includes the number of streams and transmission information for each stream.

[0087] This allows the gNB200 to understand, for example, what types of streams the UE100 will transmit to the gNB200, or what types of streams the UE100 can receive from the gNB200, and to configure the UE100 accordingly. Therefore, the mobile communication system 1 can properly perform communication using XR.

[0088] Figure 7 is a diagram showing an example of operation according to Modification 1 of the First Embodiment.

[0089] As shown in Figure 7, in step S20, the UE 100 transmits XR assist information including information about the type of traffic. Note that, as in the first embodiment, the gNB 200 may request the UE 100 to notify the gNB 200 of the XR assist information prior to step S20.

[0090] Information regarding the type of traffic includes, for example, the following:

[0091] Firstly, the information may be identification information for the transmission path used to transmit XR traffic. The transmission path identification information may be LCID or the like, as in the first embodiment.

[0092] Secondly, the information in question may also represent the number of streams.

[0093] Thirdly, the information may be transmission information for each stream. The transmission information may be information indicating at least one of the following: attitude, control, scene, video, audio, data, I (Intra-coded) stream of video, and P (Predicted) stream of video. The transmission information may also be QoS information for each stream. The transmission information may also be identification information that distinguishes each XR traffic model described in the first embodiment from others. For example, the identification information for the single-stream model in the DL stream of virtual reality (VR) described in (2.2.1) above is "XXX", and the identification information for model #3A in the UL stream of augmented reality (AR) described in (2.2.2) above is "YYY", etc. Such identification information for traffic models or types may be determined in the specification.

[0094] Fourth, XR assist information may include information indicating a desire for resources for XR traffic.

[0095] Steps S12 and beyond are the same as in the first embodiment.

[0096] (Modification 2 of the first embodiment) In the first embodiment, an example was described in which traffic information is included in the XR assist information, and in Modification 1, an example was described in which information about the type of XR traffic is included in the XR assist information, but the invention is not limited to these. For example, the XR assist information may include upper layer information about the upper layer.

[0097] Figure 8 is a diagram showing an example of operation according to Modification 2 of the First Embodiment.

[0098] As shown in Figure 8, in step S30, UE100 sends XR assist information including upper layer information to gNB200. The AS of UE100 may also include upper layer information received from an upper layer (e.g., the application layer) in the XR assist information and send it to gNB200. In addition, as in the first embodiment, gNB200 may request UE100 to notify gNB200 of the XR assist information prior to step S30.

[0099] Examples of higher-layer information include the following:

[0100] Firstly, the upper layer information may represent information related to virtual reality (VR), augmented reality (AR), or cloud gaming (CG). Furthermore, the upper layer information may represent information related to virtual reality (VR), augmented reality (AR), cloud gaming (CG), or mixed reality (MR).

[0101] Secondly, the upper layer information may also be the type of device performing XR (i.e., UE100) and / or the product name (or model number) of said device. This is because augmented reality (AR) performance or communication content may differ depending on the device. Upon receiving the upper layer information, the gNB200 can understand the traffic characteristics from the device model number information, and can also configure the UE100 according to those traffic characteristics. Furthermore, the gNB200 can understand the QoS information required for each device from the device model number information, and can also configure the UE100 according to those QoS characteristics.

[0102] Thirdly, the upper layer information may be the type of traffic model (or encoding type). For example, the type of traffic model may be identification information indicating that it is a GOP-based I-frame and P-frame. Alternatively, the type of traffic model may be identification information indicating that it is a slice-based I-slice and P-slice. Or, the type of traffic model may be identification information that identifies each of the XR traffic models described in the first embodiment.

[0103] Steps S12 and beyond are the same as in the first embodiment.

[0104] (Modification 3 of the first embodiment) In the first embodiment, it was described that UE100 transmits XR assist information to gNB200, but this is not limited to this. For example, CN20 may transmit XR assist information to gNB200.

[0105] Specifically, the access mobility management device (e.g., AMF300) transmits XR-related XR assist information to the base station (e.g., gNB200). This XR assist information may also be transmitted from the session management device (e.g., SMF (Session Management Function)) to the AMF300 or gNB200. Here, XR includes virtual reality, augmented reality, and mixed reality, and represents an environment that merges the real world and virtual space.

[0106] In the third modified example, the gNB200 can also configure settings for XR communication with the UE100 based on the XR assist information. Therefore, similar to the first embodiment, the mobile communication system 1 can properly perform XR-related communications. However, since the XR assist information is transmitted from the CN20 to the gNB200, the UE100 does not need to transmit the XR assist information. As a result, the radio resources used for transmitting the XR assist information can be used for other wireless communications.

[0107] Figure 9 is a diagram showing an example of operation according to Modification 3 of the First Embodiment.

[0108] As shown in Figure 9, in step S40, CN20 may receive traffic information from the XR application server 400. The XR application server 400 communicates with the UE100 regarding XR via CN20 and gNB200 of the mobile communication system 1. Therefore, the XR application server 400 can hold traffic information regarding XR traffic. The traffic information in the modified example 3 may include the same information as the traffic information described in the first embodiment.

[0109] In step S41, CN20 (e.g., AMF300) transmits XR assist information to gNB200. The XR assist information includes traffic information. This traffic information may be traffic information received from the XR application server 400. This traffic information includes identification information relating to the transmission path that transmits the XR traffic, similar to the traffic information in the first embodiment. This identification information may be represented by a QoS flow ID, a PDU session ID, an MBS session ID, or an XR session ID. The XR assist information may also include information relating to the type of traffic as described in Modification 1. Alternatively, the XR assist information may include upper-layer information relating to the upper layer as described in Modification 2. Prior to step S41, gNB200 may request CN20 to transmit the XR assist information to gNB200. This request may be transmitted, for example, by being included in an NG message.

[0110] In step S42, the gNB200 configures the UE100 for XR communication based on the XR assist information. Similar to the first embodiment, this configuration may also be such that DL is set to C-DRX (or SPS) and UL is set to CG.

[0111] The third modified example described an example in which XR assist information is transmitted from CN20 to gNB200. Furthermore, during a handover, the XR assist information may be transferred from the handover source gNB200-1 (or source cell) to the handover destination gNB200-2 (or target cell). Specifically, the handover source gNB200-1 (or source cell) or AMF300 transmits the XR assist information to the handover destination gNB200-2 (or target cell) along with a message requesting the handover.

[0112] [Second Embodiment] Modification 3 of the first embodiment describes an example in which CN20 transmits XR assist information to gNB200. In this case, gNB200 can set up a bearer (DRB: Data Radio Bearer) with UE100 based on the XR assist information.

[0113] In the second embodiment, an example is described in which the gNB200 sends configuration information, including information about the bearer setting, to the UE100 when a bearer setting is made.

[0114] Specifically, firstly, the base station (e.g., gNB200) configures the transmission path for transmitting XR traffic. Secondly, the base station transmits configuration information regarding the configured transmission path to the user device (e.g., UE100). Thirdly, the user device transmits XR assist information, including identification information regarding the transmission path, to the base station based on the configuration information. Here, the configuration information includes information linking the identification information to the XR session ID.

[0115] As a result, for example, as described in the first embodiment, the UE100 can also transmit XR assist information, including a bearer ID (e.g., identification information related to the transmission path), to the gNB200. Therefore, it becomes possible to properly perform XR-related communications in the mobile communication system 1.

[0116] The operations performed in the second embodiment may be performed before the operations performed in the first embodiment. However, the second embodiment does not necessarily presuppose the operations of the first embodiment and may be performed independently.

[0117] Figure 10 is a diagram illustrating an example of operation according to the second embodiment.

[0118] As shown in Figure 10, in step S50, the gNB200 configures the transmission path for XR transmission for the UE. This transmission path configuration includes, for example, the following:

[0119] Firstly, the transmission path configuration may include information linking bearer IDs and XR session IDs. For example, if gNB200 links a bearer configured between gNB200 and UE100 to an XR session configured between UPF300 and UE100, the transmission path configuration may include information linking the XR session ID of the XR session and the bearer ID of the bearer. Instead of bearer ID, LCID, RLC channel ID, or RNTI may be used. Alternatively, QoS flow ID may be used instead of bearer ID. The XR session ID may be the stream ID of each stream in the XR traffic. Alternatively, the XR session ID may be the traffic type assigned to each stream (such as I stream, P stream, or attitude and / or control). Alternatively, the XR session ID may be an identifier that simply indicates that it is used for an XR session. Alternatively, the transmission path configuration may include information on a set of multiple bearers (or information on linking multiple bearers). For example, this could be linking information to connect two bearers for use in a single XR transmission. For example, it could be linking a bearer for the I-stream with a bearer for the P-stream.

[0120] Secondly, the transmission path configuration may include information linking TMGI (Temporary Mobile Group Identity) and XR session ID. However, if UE100 uses MBS (Multicast and Broadcast Services), gNB200 may set this linking information. For example, gNB200 may set this linking information after UE100 has sent MSB interest information to gNB200. Linking TMGI and XR session ID may be effective when increasing capacity using MBS in the DL direction. Note that MRB ID (MBS Radio Bearer ID), LCID, or RLC channel ID may be used instead of TMGI. Also, RNTI such as G-RNTI (Group-RNTI) or G-CS-RNTI (Group Configured Scheduling RNTI) may be used instead of TMGI.

[0121] Thirdly, the transmission path configuration may include information linking the DRX setting and the XR session ID. In this case as well, the gNB200 may include this linking information in the transmission path configuration when it has configured the DRX setting in the DL direction for XR transmission. Furthermore, the transmission path configuration may include information linking the SPS setting and the XR session ID. In this case as well, the gNB200 may include this linking information in the transmission path configuration when it has configured the SPS setting in the DL direction for XR transmission.

[0122] Fourth, the transmission path configuration may include information linking the CG (Configured Grant) setting with the XR session ID. During the CG setting period, only data transmission for the XR session may be permitted. In this case as well, the gNB200 may include this linking information in the transmission path configuration when it has configured the CG in the UL direction for XR transmission.

[0123] Fifth, the transmission path configuration may include information linking the identification information of the transmission path, such as a bearer ID, with the type of XR traffic. For example, it may be information linking bearer #1 with an I-stream (or I-frame), or information linking bearer #2 with a P-stream (or P-frame). Similar to Modification 1 of the first embodiment, the gNB200 can transmit the type of traffic used in the transmission path to the UE100.

[0124] In step S51, the gNB200 sends configuration information to the UE100. The gNB200 may send an RRC message containing the configuration information (for example, an RRC Setup message). Alternatively, the gNB200 may send a MAC CE containing the configuration information.

[0125] In step S52, UE100 applies the transmission path settings configured by gNB200 by applying the received configuration information.

[0126] [Third Embodiment] XR transmission may include the transmission of video data (or video streams), as described in the first embodiment. Therefore, it may involve the transmission of a large amount of data compared to other methods. In this case, a large amount of wireless resources may be required for wireless transmission of XR. On the other hand, when XR transmission is completed, it may be better to release the wireless resources used for XR transmission as quickly as possible.

[0127] Therefore, in the third embodiment, an example will be described in which the UE100 notifies the gNB200 when the transmission of XR traffic has ended or when the transmission of XR traffic has been temporarily interrupted. Specifically, the user device (e.g., UE100) transmits either termination information indicating that the transmission of XR traffic has ended, or interruption information indicating that the transmission of XR traffic has been interrupted, to the base station (e.g., gNB200). Note that the third embodiment may be implemented after the XR assist information described in the first embodiment has been transmitted from the UE100 to the gNB200 and the settings related to XR have been made. However, the third embodiment may be implemented without presupposing the first embodiment.

[0128] Figure 11 is a diagram illustrating an example of operation according to the third embodiment.

[0129] As shown in Figure 11, in step S60, the UE100 is configured for the XR session. For example, the settings for the XR session include DRX (or SPS) settings for XR transmission in the DL direction, and CG (Configured Grant) settings for XR transmission in the UL direction. Alternatively, the transmission path settings for XR transmission described in the second embodiment may be used for the XR session.

[0130] In step S61, the AS of UE100 receives notification from a higher layer (e.g., the application layer) that the XR application has ended. The AS of UE100 may also receive notification from a higher layer that the XR session has ended. Alternatively, the AS of UE100 may receive notification from a higher layer that the XR transmission has ended. Alternatively, the AS of UE100 may receive notification from a higher layer that the XR transmission (or XR session or XR application) has been paused.

[0131] In step S62, UE100 sends termination information to gNB200 indicating that the XR session has ended. UE100 may also send request information to gNB200 requesting deconfiguration for the XR session. Alternatively, UE100 may send suspend information to gNB200 indicating that the transmission of XR traffic will be temporarily suspended. The termination information, request information, or suspend information may include identification information for the transmission path associated with the XR session. This identification information may be any of the LCID, bearer ID, RLC channel ID, RNTI, and XR session ID, as in the first embodiment. UE100 may also send an RRC message containing the termination information, request information, or suspend information to gNB200. Furthermore, UE100 may send a MAC CE containing the termination information, request information, or suspend information to gNB200. Furthermore, UE100 may send DCI containing termination information, request information, or suspend information to gNB200.

[0132] In step S63, the gNB200 deconfigures the settings for the XR session upon receiving termination information. The gNB200 may also temporarily suspend the settings for the XR session upon receiving suspend information.

[0133] Furthermore, UE100 may send a notification to gNB200 indicating that it is starting (or restarting) XR communication before actually starting (or restarting) XR communication. That is, when XR communication is started (or restarted), UE100 may notify gNB200 of information indicating that the XR session has been started (or restarted, or that the start and / or restart will occur in the near future). This notification may be a configuration request for the XR session. This notification may include information about the transmission path associated with the XR session. If the notification indicates that the start and / or restart will occur in the near future, it may include information indicating the time of the start and / or restart (e.g., the start time and the time until the start). This notification may be included in an RRC message or MAC CE and sent from UE100 to gNB200.

[0134] [Other embodiments] A program may be provided that causes a computer to perform each of the processes that UE100 or gNB200 performs. The program may be recorded on a computer-readable medium. Using a computer-readable medium, it is possible to install the program on a computer. Here, the computer-readable medium on which the program is recorded may be a non-transient recording medium. The non-transient recording medium is not particularly limited, but may be a recording medium such as a CD-ROM or DVD-ROM.

[0135] Alternatively, the circuits that perform each process carried out by the UE100 or gNB200 may be integrated, and at least a portion of the UE100 or gNB200 may be configured as a semiconductor integrated circuit (chipset, SoC: System on a chip).

[0136] Although one embodiment has been described in detail above with reference to the drawings, the specific configuration is not limited to that described above, and various design changes can be made without departing from the gist of the work. Furthermore, it is possible to combine all or part of each embodiment, each operation, each process, and each step, as long as they do not contradict each other.

[0137] The terms “based on” and “depending on” used in this disclosure do not mean “based solely on” or “depending solely on” unless otherwise specified. “Based on” means both “based solely on” and “at least partially on.” Similarly, “depending on” means both “at least partially on” and “at least partially on.” Furthermore, the terms “include,” “comprise,” and variations thereof do not mean that only the listed items are included; they may include only the listed items, or they may include additional items in addition to the listed items. Also, the term “or” used in this disclosure is not intended to mean exclusive OR. Moreover, any reference to elements using designations such as “first,” “second,” etc., used in this disclosure does not generally limit the quantity or order of those elements. These designations may be used herein as a convenient way to distinguish between two or more elements. Therefore, references to the first and second elements do not imply that only two elements may be adopted therein, or that the first element must precede the second element in any way. In this disclosure, where articles are added by translation, such as a, an, and the in English, these articles shall be plural unless it is clearly indicated by the context that they are not.

[0138] This application claims priority to Japanese Patent Application No. 2022-070308 (filed on April 21, 2022), and all of its contents are incorporated into the specification of this application.

[0139] (Note) In one embodiment, (Note 1) a communication control method in a mobile communication system, comprising the step of a user device transmitting XR (eXtended Reality) related XR assist information to a base station, wherein XR includes virtual reality (VR), augmented reality (AR), and mixed reality (MR), and represents an environment that fuses the real world and virtual space.

[0140] (Note 2) In the communication control method described in (Note 1) above, the XR assist information may include traffic information relating to the traffic characteristics of the XR traffic.

[0141] (Note 3) In the communication control method described in (Note 1) or (Note 2) above, the traffic information may represent at least one of the following: identification information relating to the transmission path that transmits the XR traffic, throughput of the XR traffic, delay tolerance of the XR traffic, traffic pattern of the XR traffic, identifier indicating the transmission direction of the XR traffic, QoS (Quality of Service) value, and the difference between the CG (Configured Grant) setting and the timing of receiving a packet from the upper layer.

[0142] (Note 4) In any of the communication control methods described in (Note 1) to (Note 3) above, the identification information may be any of the logical channel ID, bearer ID, RLC channel ID, RNTI (Radio Network Temporary Identifier), and XR session ID used to transmit the XR traffic.

[0143] (Note 5) In any of the communication control methods described in (Note 1) to (Note 4) above, if the XR traffic is multi-stream, the XR assist information may include the traffic information for each stream.

[0144] (Note 6) In any of the communication control methods described in (Note 1) to (Note 5) above, the XR assist information may include information regarding the type of XR traffic.

[0145] (Note 7) In any of the communication control methods described in (Note 1) to (Note 6) above, the information relating to the type of XR traffic may include the number of streams and transmission information for each stream.

[0146] (Note 8) In any of the communication control methods described in (Note 1) to (Note 7) above, the transmission information may be information indicating at least one of the following for each stream: attitude, control, scene, video, audio, data, I (Intra-coded) video stream, and P (Predicted) video stream.

[0147] (Note 9) In any of the communication control methods described in (Note 1) to (Note 8) above, the XR assist information may include upper layer information relating to the upper layer.

[0148] (Note 10) In any of the communication control methods described in (Note 1) to (Note 9) above, the upper layer information may include at least one of the following: information representing virtual reality, augmented reality, and cloud gaming; information regarding the type and product name of the user device; and information representing the traffic model.

[0149] (Note 11) In any of the communication control methods described in (Note 1) to (Note 10) above, the method further includes the steps of: the base station configuring the transmission path for transmitting the XR traffic; and the base station transmitting configuration information relating to the transmission path to the user device, wherein the step of transmitting the XR assist information to the base station includes the step of the user device transmitting the XR assist information, including the identification information, to the base station based on the configuration information, and the configuration information may include information linking the identification information and the XR session ID.

[0150] (Note 12) In any of the communication control methods described in (Note 1) to (Note 11) above, the user device may further include a step of transmitting either termination information indicating that it has terminated the transmission of XR traffic, or suspend information indicating that it has temporarily suspended the transmission of XR traffic, to the base station.

[0151] Furthermore, in one embodiment, (Appendix 13) a communication control method in a mobile communication system, comprising the step of an access mobility management device transmitting XR assist information relating to XR to a base station, wherein XR includes virtual reality, augmented reality, and mixed reality, and represents an environment that merges the real world and virtual space.

[0152] (Note 14) In the communication control method described in (Note 13) above, the XR assist information includes identification information relating to a transmission path for transmitting XR traffic, and the identification information can be represented by any of the following: QoS flow ID, PDU (Protocol Data Unit) session ID, MBS (Multicast and Broadcast Services) session ID, and XR session ID. [Explanation of symbols]

[0153] 1: Mobile communication systems 20 :CN 100 :UE 110: Receiver 120: Transmitter 130: Control Unit 200 :gNB 210: Transmitter 220: Receiving unit 230: Control Unit 300: AMF

Claims

1. A communication control method in a mobile communication system, The user device transmits assist information relating to XR (eXtended Reality), which includes timing information indicating the timing at which the user device receives a packet, to the first network node. The first network node performs a handover for the user device to the second network node, The first network node transmits the timing information to the second network node when performing the handover. Communication control method.

2. A first network node used in a mobile communication system, A receiving unit receives assistance information related to XR (eXtended Reality), which includes timing information indicating the timing at which the user device receives packets, from the user device. A control unit that performs a handover for the user device to a second network node, The system includes a transmission unit that transmits the timing information to the second network node when performing the handover. The first network node.

3. A mobile communication system, The user device transmits assist information relating to XR (eXtended Reality), which includes timing information indicating the timing at which the user device receives a packet, to the first network node. The first network node performs a handover for the user device to the second network node. When the first network node performs the handover, it transmits the timing information to the second network node. Mobile communication system.

4. On the first network node, The process of receiving assist information related to XR (eXtended Reality), which includes timing information indicating the timing at which the user device receives packets, from the user device, The process of performing a handover for the user device to a second network node, When performing the aforementioned handover, the process of sending the timing information to the second network node is performed. program.

5. A chipset for the first network node, The user device receives assist information related to XR (eXtended Reality), which includes timing information indicating the timing at which the user device receives packets. Performing a handover for the user device to a second network node, When performing the aforementioned handover, the timing information is transmitted to the second network node. Chipset.

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