Communication control method, remote user device, system, processor, program and network node

Abstract

To provide a communication control method using a relay user device for relaying communication between a base station and a remote user device.SOLUTION: A communication control method for use in a mobile communication system includes establishing a connection between a remote user device 100-1 and a relay user device 100-2, and performing a random access procedure for establishing a connection between the remote user device and a base station 200-1. The performing of the random access procedure includes a proxy operation in which the relay user device performs at least part of an operation performed by a MAC (Medium Access Control) layer in the random access procedure on behalf of the remote user device.SELECTED DRAWING: Figure 10

Description

Technical Field

[0001] The present invention relates to a communication control method used in a mobile communication system.

Background Art

[0002] In a mobile communication system based on 3GPP (3rd Generation Partnership Project) (registered trademark; the same applies hereinafter) standards, a side-link relay technology that uses a user device as a relay node has been studied. Side-link relay is a technology in which a relay node called a relay user device (Relay UE) intervenes in the communication between a base station and a remote user device (Remote UE) and performs relay for this communication.

Prior Art Documents

Non-Patent Documents

[0003]

Non-Patent Document 1

Summary of the Invention

[0004] The communication control method according to the first aspect is a method using a relay user device for relaying communication between a base station and a remote user device. The communication control method includes establishing a connection between the remote user device and the relay user device, and performing a random access procedure for establishing a connection between the remote user device and the base station. Performing the random access procedure includes proxy operations in which the relay user device performs at least some of the operations performed by the MAC (Medium Access Control) layer in the random access procedure instead of the remote user device.

[0005] A second aspect of the communication control method is a method that uses a relay user device for relaying communication between a base station and a remote user device. The communication control method includes establishing a connection between the remote user device and the relay user device, and the remote user device transmitting an RRC (Radio Resource Control) message from the remote user device to the base station via the relay user device for the remote user device to connect to the base station. Transmitting the RRC message includes transmitting the RRC message which includes information indicating that the RRC message has been transmitted via the relay user device.

[0006] A third aspect of the communication control method is a method that uses a relay user device for relaying communication between a base station and a remote user device. The communication control method comprises the remote user device transmitting and receiving a first RRC (Radio Resource Control) message used for communication control with the base station via the relay user device on a first signaling radio bearer, and the remote user device transmitting and receiving a second RRC message used for communication control with the relay user device on a second signaling radio bearer different from the first signaling radio bearer.

[0007] A fourth aspect of the communication control method is a method that uses a relay user device for relaying communication between a base station and a remote user device. The communication control method comprises the remote user device receiving an RRC (Radio Resource Control) message from the base station via the relay user device, and the remote user device performing a notification operation to notify the relay user device of the contents of the RRC message.

[0008] A fifth aspect of the communication control method is a method that uses a relay user device for relaying communication between a base station and a remote user device. The communication control method comprises the base station receiving link identification information that identifies the wireless link between the remote user device and the relay user device from the remote user device or the relay user device, and the base station controlling the measurement of the wireless state between the remote user device and the relay user device based on the link identification information. [Brief explanation of the drawing]

[0009] [Figure 1] This figure shows the configuration of a mobile communication system according to one embodiment. [Figure 2] This diagram shows the configuration of a UE (User Equipment) according to one embodiment. [Figure 3] This diagram shows the configuration of a gNB (base station) according to one embodiment. [Figure 4] This diagram shows the protocol stack configuration for the user plane's wireless interface. [Figure 5] This diagram shows the protocol stack configuration for the control plane's wireless interface. [Figure 6] This figure shows a hypothetical scenario in a mobile communication system according to one embodiment. [Figure 7] This figure shows an example of a protocol stack in a hypothetical scenario according to one embodiment. [Figure 8] This figure shows an example of a protocol stack having a PC5 RRC layer according to one embodiment. [Figure 9] This figure shows another example of a protocol stack having a PC5 RRC layer according to one embodiment. [Figure 10] This figure shows operation pattern 1 of the RRC connection establishment operation between a remote UE and a gNB according to one embodiment. [Figure 11] This figure shows operation pattern 2 of the RRC connection establishment operation between a remote UE and a gNB according to one embodiment. [Figure 12]This figure shows an operation pattern 1 relating to an RRC message from a gNB to a remote UE according to one embodiment. [Figure 13] This figure shows an operation pattern 1 relating to an RRC message from a gNB to a remote UE according to one embodiment. [Figure 14] This figure shows a signaling wireless bearer according to one embodiment. [Figure 15] This figure shows operation pattern 1 of the wireless status measurement operation between a remote UE and a relay UE according to one embodiment. [Figure 16] This figure shows operation pattern 2 of the wireless status measurement operation between a remote UE and a relay UE according to one embodiment. [Modes for carrying out the invention]

[0010] In the background technology, the relay user equipment cannot interpret the content of RRC messages transmitted and received by the base station and remote user equipment via the relay user equipment. In other words, from the perspective of the RRC connection between the base station and the remote user equipment, the relay user equipment is transparent. However, conventional mobile communication systems do not take this new scenario into consideration, raising concerns that they cannot properly control communications using relay user equipment.

[0011] Therefore, this disclosure aims to enable appropriate control of communications using relay user equipment.

[0012] A mobile communication system according to one 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.

[0013] (Configuration of mobile communication systems) First, the configuration of a mobile communication system according to an embodiment will be described. FIG. 1 is a diagram showing the configuration of a mobile communication system according to an embodiment. This mobile communication system complies with the 5th Generation System (5GS) of the 3GPP standard. In the following, 5GS will be taken as an example for explanation, but the LTE (Long Term Evolution) system may be at least partially applied to the mobile communication system.

[0014] As shown in FIG. 1, the 5GS 1 includes a User Equipment (UE) 100, a 5G radio access network (NG-RAN) 10, and a 5G core network (5GC) 20.

[0015] The UE 100 is a movable wireless communication device. The UE 100 may be any device as long as it is a device used by a user. For example, the UE 100 may be a mobile phone terminal (including a smartphone), a tablet terminal, a notebook PC, a communication module (including a communication card or a chipset), a sensor or a device provided in a sensor, a vehicle or a device provided in a vehicle (Vehicle UE), and / or an aircraft or a device provided in an aircraft (Aerial UE).

[0016] 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 / or a measurement control function for mobility control and scheduling. A "cell" is used as a term indicating the smallest unit of a wireless communication area. A "cell" is also used as a term indicating a function or resource for performing wireless communication with the UE 100. One cell belongs to one carrier frequency.

[0017] 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.

[0018] 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 data transfer control. 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.

[0019] Figure 2 is a diagram showing the configuration of the UE 100 (user equipment).

[0020] As shown in Figure 2, the UE 100 includes a receiving unit 110, a transmitting unit 120, and a control unit 130.

[0021] The receiving unit 110 performs various types of reception 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.

[0022] The transmitting unit 120 performs various types of 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 wireless signal and transmits it from the antenna.

[0023] The control unit 130 performs various controls on the UE100. 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 processing by the processor. The processor may include a baseband processor and a CPU (Central Processing Unit). The baseband processor performs modulation, demodulation, encoding, and decoding of baseband signals. The CPU executes programs stored in memory and performs various processing.

[0024] Figure 3 shows the configuration of the gNB200 (base station).

[0025] As shown in Figure 3, the gNB200 comprises a transmitting unit 210, a receiving unit 220, a control unit 230, and a backhaul communication unit 240.

[0026] The transmitting unit 210 performs various types of 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.

[0027] 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.

[0028] The control unit 230 performs various controls in the gNB200. 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, and decoding of baseband signals. The CPU executes programs stored in memory and performs various processing.

[0029] The backhaul communication unit 240 is connected to an adjacent base station via an inter-base station interface. The backhaul communication unit 240 is connected to the AMF / UPF300 via a base station-core network interface. The gNB may consist of a CU (Central Unit) and a DU (Distributed Unit) (i.e., functionally separated), and the two units may be connected via an F1 interface.

[0030] Figure 4 shows the configuration of the protocol stack for the user plane's wireless interface that handles data.

[0031] As shown in Figure 4, the user plane radio interface protocol has 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.

[0032] 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.

[0033] The MAC layer performs data priority control, retransmission processing using Hybrid ARQ (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.

[0034] 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.

[0035] The PDCP layer performs header compression / decompression, and encryption / decryption.

[0036] The SDAP layer maps IP flows, which are the units under which the core network performs QoS 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, SDAP may not be necessary.

[0037] Figure 5 shows the configuration of the protocol stack of the wireless interface of the control plane that handles signaling (control signals).

[0038] As shown in Figure 5, the protocol stack of the control plane's wireless interface has an RRC (Radio Resource Control) layer and a NAS (Non-Access Stratum) layer instead of the SDAP layer shown in Figure 4.

[0039] 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 RRC connected mode. If there is no connection (RRC connection) between the RRC of the UE100 and the RRC of the gNB200, the UE100 is in RRC idle mode.

[0040] The NAS layer, located above the RRC layer, handles session management and mobility management, among other things. NAS signaling is transmitted between the UE100's NAS layer and the AMF300's NAS layer.

[0041] In addition to the wireless interface protocol, the UE100 also has an application layer and other components.

[0042] (Assumed scenario) Next, we will describe a hypothetical scenario in a mobile communication system 1 according to one embodiment. Figure 6 is a diagram showing a hypothetical scenario.

[0043] As shown in Figure 6, we assume a scenario in which a relay UE100-2 intervenes in the communication between gNB200-1 and remote UE100-1, and a sidelink relay is used to relay this communication.

[0044] Remote UE100-1 communicates wirelessly with relay UE100-2 (sidelink communication) over the PC5 interface (sidelink), which is the inter-UE interface. Relay UE100-2 communicates wirelessly with gNB200-1 (Uu communication) over the NR Uu wireless interface. As a result, remote UE100-1 communicates indirectly with gNB200-1 via relay UE100-2. Uu communication includes uplink communication and downlink communication.

[0045] Figure 7 shows an example of a protocol stack in a hypothetical scenario. In Figure 7, the MAC layer and PHY layer, which are lower layers of the RLC layer, are not shown.

[0046] As shown in Figure 7, the gNB200-1 may be divided into a CU and a DU. An F1-C interface (Intra-donor F1-C) is established between the CU and the DU.

[0047] The PDCP layer of the CU in gNB200-1 and the PDCP layer of the remote UE100-1 communicate with each other via the relay UE100-2. The RRC layer of the CU and the RRC layer of the remote UE100-1 also communicate with each other via the relay UE100-2. An adaptation layer may be provided as a layer above the RLC layer in the DU, relay UE100-2, and remote UE100-1.

[0048] Although not shown in Figure 7, the RRC layer of the CU and the RRC layer of the relay UE100-2 communicate with each other. The PDCP layer of the CU and the PDCP layer of the relay UE100-2 also communicate with each other.

[0049] Furthermore, both the remote UE100-1 and the relay UE100-2 may have an RRC layer for PC5. Such an RRC layer is called "PC5 RRC". The PC5 RRC layer of the remote UE100-1 and the PC5 RRC layer of the relay UE100-2 communicate with each other.

[0050] Figure 8 shows an example of a protocol stack with a PC5 RRC layer. Figure 9 shows another example of a protocol stack with a PC5 RRC layer. In Figures 8 and 9, an example is shown where gNB200-1 is not separated into DU and CU, but gNB200-1 may be separated into DU and CU.

[0051] As shown in Figure 8, the gNB200-1 has an RRC layer, a PDCP layer (Uu), an RLC layer (Uu), a MAC layer (Uu), and a PHY layer (Uu) used for communication on the Uu interface (Uu communication). The gNB200-1 also has an adaptation layer between the PDCP layer (Uu) and the RLC layer (Uu).

[0052] The relay UE100-2 has an RRC layer (not shown), an RLC layer (Uu), a MAC layer (Uu), and a PHY layer (Uu) used for communication on the Uu interface (Uu communication). Furthermore, the relay UE100-2 has a PC5 RRC layer, a PDCP layer (PC5), an RLC layer (PC5), a MAC layer (PC5), and a PHY layer (PC5) used for communication on the PC5 interface (PC5 communication). In addition, the relay UE100-2 has an adaptation layer as a layer above the PC5 RRC layer.

[0053] The remote UE100-1 has an RRC layer and a PDCP layer (Uu) used for communication on the Uu interface (Uu communication). The remote UE100-1 also has a PC5 RRC layer, a PDCP layer (PC5), an RLC layer (PC5), a MAC layer (PC5), and a PHY layer (PC5) used for communication on the PC5 interface (PC5 communication). Furthermore, the remote UE100-1 has an adaptation layer between the PDCP layer (Uu) and the PC5 RRC layer.

[0054] As shown in Figure 9, the remote UE100-1 does not necessarily have an adaptation layer. In the example shown in Figure 9, the adaptation layer of the relay UE100-2 is located above the RLC layer (Uu).

[0055] (Operation of mobile communication systems) Next, the operation of the mobile communication system 1 according to one embodiment will be described.

[0056] (1) Establishment of RRC connection between remote UE and gNB This document describes the procedure for establishing an RRC connection between the remote UE100-1 and gNB200-1.

[0057] (1.1) Operation Pattern 1 This operation pattern 1 includes the steps of establishing a connection between the remote UE100-1 and the relay UE100-2, and performing a random access procedure to establish a connection between the remote UE100-1 and the gNB200-1. The step of performing the random access procedure includes a proxy operation step in which the relay UE100-2 performs at least some of the operations that the MAC layer performs in the random access procedure on behalf of the remote UE100-1.

[0058] As shown in Figures 8 and 9, the remote UE100-1 has the MAC layer of the PC5 interface but not the MAC layer of the Uu interface. On the other hand, the random access procedure includes operations that the MAC layer of the Uu interface should perform. Therefore, by having the relay UE100-2 perform at least some of the operations that the MAC layer would perform in the random access procedure on behalf of the remote UE100-1, it becomes possible to implement a random access procedure for establishing a connection between the remote UE100-1 and the gNB200-1.

[0059] Figure 10 shows operation pattern 1 of the RRC connection establishment operation between remote UE100-1 and gNB200-1. In Figure 10, non-essential steps are shown with dashed lines.

[0060] As shown in Figure 10, in step S101, the remote UE100-1 and the relay UE100-2 establish a PC5 RRC connection. A PC5 RRC connection refers to the connection established between the PC5 RRC layer of the remote UE100-1 and the PC5 RRC layer of the relay UE100-2. On the other hand, an RRC connection may not yet be established between the relay UE100-2 and the gNB200-1.

[0061] Furthermore, in the PC5 RRC connection, it may be confirmed that the relay UE100-2 is capable of relaying traffic from the remote UE100-1 to the gNB200-1. For example, the remote UE100-1 notifies the relay UE100-2 of a relay request, and the relay UE100-2 accepts the relay request. Then, the relay UE100-2 permits the communication of the traffic to be relayed to the remote UE100-1. Such confirmation operations can also be applied to each operation pattern described later.

[0062] Prior to step S102, the remote UE100-1 decides to perform the RRC connection establishment process with gNB200-1. For example, in response to a connection establishment request from a higher layer (NAS layer), the RRC layer generates a message (RRC Setup Request, RRC Resume Request, or RRC Reestablishment Request) to establish the RRC connection and provides the generated message to the lower layer. In such cases, the remote UE100-1 usually triggers a random access procedure to gNB200-1. On the other hand, when relay UE100-2 performs relaying, the remote UE100-1 uses the PC5 MAC entity for communication and does not use the Uu MAC entity. That is, the Uu MAC entity does not need to perform a random access procedure. Therefore, the remote UE100-1 decides not to trigger a random access procedure. In other words, the remote UE100-1 decides not to trigger a random access procedure when establishing (resuming) an RRC connection if it does not use a MAC entity associated with Uu and / or if it uses a MAC entity associated with PC5 where relaying is performed. The remote UE100-1 may decide to send a proxy request message to the relay UE100-2 requesting further proxy action.

[0063] In step S102, the remote UE 100-1 sends a proxy request message to the relay UE 100-2 requesting proxy operation. The proxy request message may be a message requesting the relay UE 100-2 to send a random access preamble to the gNB 200-1. The proxy request message is a message sent from a predetermined layer of the remote UE 100-1 to a predetermined layer of the relay UE 100-2. The predetermined layer is the MAC layer (PC5), RLC layer (PC5), PDCP layer (PC5), PC5 RRC layer, or adaptation layer.

[0064] In step S103, the relay UE 100-2 sends a random access preamble to the gNB 200-1 in response to the receipt of the proxy request message. The random access preamble is sent from the MAC layer (Uu) of the relay UE 100-2 to the MAC layer (Uu) of the gNB 200-1. The random access preamble constitutes the first message (called "Msg1") in the random access procedure. Note that in step S103, the relay UE 100-2 may send the random access preamble to the gNB 200-1 in response to the establishment of the PC5 RRC connection (step S101), even if it has not received the proxy request message. Also, if the relay UE 100-2 has already established an RRC connection with the gNB 200-1, steps S103 and S104 may be omitted, and the response message in step S105 may be sent from the relay UE 100-2 to the remote UE 100-1.

[0065] In step S104, gNB200-1 sends a random access response to relay UE100-2. Relay UE100-2 receives the random access response. The random access response is sent from the MAC layer (Uu) of gNB200-1 to the MAC layer (Uu) of relay UE100-2. The random access response constitutes the second message (called "Msg2") in the random access procedure. The random access response includes an uplink grant indicating the uplink radio resource allocated by gNB200-1 to relay UE100-2, and a timing advance value that adjusts the uplink transmission timing of relay UE100-2.

[0066] Here, the sending and receiving of Msg1 in step S103 and the sending and receiving of Msg2 in step S104 correspond to the operations performed by the MAC layer in the random access procedure.

[0067] In step S105, the relay UE 100-2 sends an acknowledgment message (ACK) to the remote UE 100-1 in response to receiving a random access response from gNB 200-1. The acknowledgment message is a message sent from a predetermined layer of the relay UE 100-2 to a predetermined layer of the remote UE 100-1. The predetermined layer is the MAC layer (PC5), RLC layer (PC5), PDCP layer (PC5), PC5 RRC layer, or adaptation layer.

[0068] The response message may also be sent when the PC5 RRC connection in step S101 is established. For example, if relay UE100-2 has already established an RRC connection with gNB200-1, it may send the response message when it has completed the process of establishing an RRC connection with remote UE100-1 and / or when it performs (permits) relay operation.

[0069] In step S106, upon receiving a response message from relay UE 100-2, remote UE 100-1 sends an RRC message to gNB200-1 via relay UE 100-2 to establish a connection with gNB200-1. Such an RRC message constitutes the third message (referred to as "Msg3") in the random access procedure. The RRC message is an RRC setup request message requesting the establishment of an RRC connection. However, the RRC message may also be an RRC re-establishment request message requesting the re-establishment of an RRC connection, or an RRC recovery request message requesting the restoration of an interrupted RRC connection.

[0070] In step S107, gNB200-1, upon receiving Msg3 from remote UE100-1, sends an RRC message to remote UE100-1 via relay UE100-2. Such an RRC message constitutes the fourth message (referred to as "Msg4") in the random access procedure. The RRC message is assumed to be an RRC setup message, although it may also be an RRC re-establishment message or an RRC recovery message.

[0071] In step S108, in response to receiving Msg4 from gNB200-1, remote UE100-1 sends an RRC message to gNB200-1 via relay UE100-2. Such an RRC message constitutes the fifth message (referred to as "Msg5") in the random access procedure. The RRC message is assumed to be an RRC setup completion message, however, the RRC message may also be an RRC re-establishment completion message or an RRC recovery completion message.

[0072] In step S109, an RRC connection is established (or re-established or restored) between the remote UE100-1 and gNB200-1.

[0073] (1.2) Operation Pattern 2 This operation pattern 2 includes the steps of establishing a connection between the remote UE 100-1 and the relay UE 100-2, and the remote UE 100-1 sending an RRC message to gNB200-1 via the relay UE 100-2 for the remote UE 100-1 to connect with gNB200-1. The step of sending the RRC message includes sending an RRC message that includes information indicating that an RRC message has been sent via the relay UE 100-2 (hereinafter referred to as "remote information"). Here, the RRC message containing the remote information is assumed to be Msg3 or Msg5, but below, an example of including the remote information in Msg3 will be mainly described.

[0074] As described above, from the perspective of the RRC connection between gNB200-1 and remote UE100-1, the relay UE100-2 is transparent, and it is difficult for the RRC layer (Uu) of gNB200-1 to determine whether the Msg3 (or Msg5) it received was sent via relay UE100-2. For this reason, when remote UE100-1 sends Msg3 (or Msg5) containing remote information to gNB200-1, gNB200-1 can properly determine whether or not the connection request is via relay UE100-2.

[0075] In this operation pattern 2, the step of sending an RRC message may omit the sending and receiving of a random access preamble (Msg1) and a random access response (Msg2), and may also include the step of sending the RRC message from the remote UE100-1 to the gNB200-1 via the relay UE100-2. In other words, unlike operation pattern 1 described above, this operation pattern 2 may not require the sending and receiving of Msg1 and Msg2.

[0076] Figure 11 shows operation pattern 2 of the RRC connection establishment operation between remote UE100-1 and gNB200-1. In Figure 11, non-essential steps are indicated by dashed lines.

[0077] As shown in Figure 11, in step S201, relay UE100-2 establishes an RRC connection with gNB200-1.

[0078] In step S202, the remote UE100-1 and the relay UE100-2 establish a PC5 RRC connection. Step S202 may be performed earlier than step S201.

[0079] In step S203, the remote UE 100-1 sends an RRC message (Msg3) to gNB200-1 via the relay UE 100-2 to establish a connection between the remote UE 100-1 and gNB200-1. Such an RRC message constitutes the third message (called "Msg3") in the random access procedure. Such an RRC message is an RRC setup request message requesting the establishment of an RRC connection. However, the RRC message may also be an RRC re-establishment request message requesting the re-establishment of an RRC connection, or an RRC recovery request message requesting the restoration of an interrupted RRC connection.

[0080] Here, remote UE100-1 may send an RRC message (Msg3) that includes remote information indicating that an RRC message was sent via relay UE100-2. The remote information may be a flag that is "1" if sent via relay UE100-2, and "0" otherwise. The remote information may be included in the cause field of the RRC message (Msg3).

[0081] The remote information may also be an identifier indicating relay UE100-2, for example, the C-RNTI (Cell-Radio Network Temporary Identifier) ​​of relay UE100-2. In this case, the C-RNTI may have been notified in advance from relay UE100-2 to remote UE100-1 (for example, in S202).

[0082] In step S204, gNB200-1, upon receiving Msg3 from remote UE100-1, sends an RRC message (Msg4) to remote UE100-1 via relay UE100-2. Such an RRC message is assumed to be an RRC setup message. However, the RRC message may also be an RRC re-establishment message or an RRC recovery message.

[0083] In step S205, in response to receiving Msg4 from gNB200-1, remote UE100-1 sends an RRC message (Msg5) to gNB200-1 via relay UE100-2. Such an RRC message is assumed to be an RRC setup completion message. However, the RRC message may also be an RRC re-establishment completion message or an RRC recovery completion message.

[0084] Here, the remote UE100-1 may send an RRC message (Msg5) containing remote information indicating that an RRC message was sent via the relay UE100-2. The remote UE100-1 may send an RRC message (Msg5) containing remote information without sending an RRC message (Msg3) containing remote information. The remote information may be included in the cause field of the RRC message (Msg5).

[0085] In step S206, an RRC connection is established (or re-established or restored) between the remote UE100-1 and gNB200-1.

[0086] Thus, according to this operation pattern 2, by sending an RRC message containing remote information from the remote UE100-1 to the gNB200-1 via the relay UE100-2, the gNB200-1 can understand that the connection request is via the relay UE100-2. As a result, the gNB200-1 can appropriately control the remote UE100-1 at the RRC layer.

[0087] For example, after establishing an RRC connection with the remote UE100-1, the gNB200-1 sends an RRC reset message to the remote UE100-1, which increases the timer settings for the PDCP and RRC layers beyond their normal values.

[0088] Furthermore, if the relay UE100-2 has an adaptation layer, the gNB200-1 may perform routing settings for the remote UE100-1 (e.g., logical channel mapping) on ​​the adaptation layer of the relay UE100-2.

[0089] Furthermore, after establishing an RRC connection with the remote UE100-1, the gNB200-1 can appropriately configure the RLC layer (PC5), MAC layer (PC5), and PHY layer (PC5) by sending an RRC reconfiguration message to the remote UE100-1 or relay UE100-2.

[0090] Furthermore, gNB200-1 may choose not to include the RLC settings, MAC settings, and PHY settings of the Uu interface in the RRC reconfiguration message it sends to the remote UE100-1. Specifically, gNB200-1, upon receiving an RRC message containing remote information, will not include PHY, MAC, and RLC configuration information in its RRC reconfiguration message. On the other hand, gNB200-1, upon receiving an RRC message that does not contain remote information, will include PHY, MAC, and RLC configuration information in its RRC reconfiguration message.

[0091] (2) Operation of RRC messages from gNB to remote UE Next, we will describe the operation of RRC messages from gNB200-1 to the remote UE100-1.

[0092] The operation regarding the RRC message from gNB200-1 to remote UE100-1 includes the steps of: remote UE100-1 receiving the RRC message from gNB200-1 via relay UE100-2; and remote UE100-1 performing a notification operation to notify relay UE100-2 of the contents of the RRC message.

[0093] As described above, relay UE100-2 cannot interpret the content of RRC messages sent and received by gNB200-1 and remote UE100-1 via relay UE100-2. Therefore, remote UE100-1 performs a notification operation to inform relay UE100-2 of the content of the RRC message it received from gNB200-1, so that relay UE100-2 can understand the content of the RRC message.

[0094] (2.1) Operation Pattern 1 In this operation pattern 1, the RRC message that the remote UE100-1 receives from gNB200-1 via relay UE100-2 is an RRC release message. Such an RRC release message is a message that releases or interrupts the RRC connection between the remote UE100-1 and gNB200-1. Below, an example is described in which the RRC release message is a message that releases the RRC connection between the remote UE100-1 and gNB200-1, but the RRC release message may also be a message that interrupts the RRC connection. In this case, in the following description, "release" of the RRC connection should be read as "interruption" of the RRC connection.

[0095] Figure 12 shows operation pattern 1 for RRC messages from gNB200-1 to remote UE100-1. In Figure 12, non-essential steps are shown with dashed lines.

[0096] As shown in Figure 12, in step S301, the relay UE100-2 establishes an RRC connection with gNB200-1.

[0097] In step S302, the remote UE100-1 and the relay UE100-2 establish a PC5 RRC connection. Step S302 may be performed earlier than step S301.

[0098] In step S303, the remote UE100-1 establishes an RRC connection with gNB200-1.

[0099] Subsequently, in step S304, gNB200-1 sends an RRC release message to remote UE100-1 via relay UE100-2.

[0100] Furthermore, gNB200-1 may include information in the RRC release message specifying whether or not the remote UE100-1 should remain under the control of the relay UE100-2. In other words, gNB200-1 may specify whether to maintain the PC5 RRC connection or to re-select a cell (such as gNB200-1). The remote UE100-1 will determine its waiting behavior after the RRC connection is released, according to the instructions in this specification. For example, the remote UE100-1 may decide to prioritize the cell re-selection action. Prioritizing means actions such as increasing the priority of the cell, decreasing the priority of maintaining the PC5 connection (or releasing the PC5 connection), and / or applying an offset in the re-selection decision.

[0101] In step S305, the remote UE100-1 releases the RRC connection with gNB200-1 upon receiving an RRC release message from gNB200-1.

[0102] In step S306, the remote UE 100-1 sends a notification to the relay UE 100-2 indicating the receipt of an RRC release message and / or the release of the RRC connection with gNB 200-1. Such a notification is a message sent from a predetermined layer of the remote UE 100-1 to a predetermined layer of the relay UE 100-2. The predetermined layer is the MAC layer (PC5), RLC layer (PC5), PDCP layer (PC5), PC5 RRC layer, or adaptation layer.

[0103] Instead of such explicit notification, implicit notification may be used. Remote UE100-1 may release the PC5 RRC connection with relay UE100-2 upon receiving an RRC release message or the release of the RRC connection with gNB200-1. In this case, relay UE100-2 will consider the RRC connection with gNB200-1 to have been released upon the release of the PC5 RRC connection.

[0104] In step S307, relay UE100-2 releases the RRC connection with gNB200-1 in response to notification from remote UE100-1.

[0105] (2.2) Operation Pattern 2 In this operation pattern 2, the RRC message received by the remote UE100-1 from gNB200-1 via the relay UE100-2 contains configuration information used for communication control between the relay UE100-2 and gNB200-1. The remote UE100-1 transmits the configuration information contained in this RRC message to the relay UE100-2.

[0106] Such configuration information is configuration information for the Uu interface. Hereafter, such configuration information will be referred to as "Uu RLC / MAC / PHY configuration information". The RRC message may further include configuration information used for communication control between the remote UE100-1 and the relay UE100-2 (i.e., configuration information for the PC5 interface). This allows the gNB200-1 to perform both RRC reconfiguration of the remote UE100-1 and RRC reconfiguration of the relay UE100-2 with a single RRC message sent to the remote UE100-1.

[0107] Figure 13 shows operation pattern 1 for RRC messages from gNB200-1 to remote UE100-1. In Figure 13, non-essential steps are shown with dashed lines.

[0108] As shown in Figure 13, in step S401, relay UE100-2 establishes an RRC connection with gNB200-1.

[0109] In step S402, the remote UE100-1 and the relay UE100-2 establish a PC5 RRC connection. Step S402 may be performed earlier than step S401.

[0110] In step S403, the remote UE100-1 establishes an RRC connection with gNB200-1.

[0111] Subsequently, in step S404, gNB200-1 sends an RRC message to remote UE100-1 via relay UE100-2. Such an RRC message may be, for example, an RRC setup message, an RRC recovery message, an RRC re-establishment message, or an RRC reconfiguration message. The RRC message contains RLC / MAC / PHY configuration information for the Uu. The RLC / MAC / PHY configuration information may include CellGroupConfig, which is configuration information indicating the cell group configuration on the Uu interface, or it may include configuration information for the adaptation layer of relay UE100-2 (e.g., routing information).

[0112] If the remote UE100-1 receives an RRC message and the RRC message also contains configuration information for the PC5 interface, it will use this configuration information to reconfigure the RRC on the PC5 interface.

[0113] In step S405, the remote UE100-1 sends a message to the relay UE100-2 that includes the RLC / MAC / PHY configuration information of the Uu contained in the RRC message. Such a message is sent from a predetermined layer of the remote UE100-1 to a predetermined layer of the relay UE100-2. The predetermined layer is the MAC layer (PC5), RLC layer (PC5), PDCP layer (PC5), PC5 RRC layer, or adaptation layer. Upon receiving this message, the relay UE100-2 uses the RLC / MAC / PHY configuration information of the Uu to reconfigure the RRC on the Uu interface.

[0114] In step S406, relay UE100-2 sends an acknowledgment message (ACK) to remote UE100-1.

[0115] In step S407, the remote UE100-1, upon receiving an acknowledgment message (ACK), sends an RRC completion message to the gNB200-1 via the relay UE100-2. The RRC completion message may be, for example, an RRC setup completion message, an RRC recovery completion message, an RRC re-establishment completion message, or an RRC reconfiguration completion message.

[0116] Furthermore, if relay UE100-2 fails to reconfigure the RRC using Uu's RLC / MAC / PHY configuration information, it may send a negative acknowledgment message (NACK) to remote UE100-1 instead of an acknowledgment message (ACK). Upon receiving the negative acknowledgment message (NACK), remote UE100-1 may consider that the RRC reconfiguration has failed and initiate the RRC re-establishment process. In this RRC re-establishment process, remote UE100-1 may include information indicating that the RRC reconfiguration at relay UE100-2 failed in the Cause field of the RRC re-establishment request message sent to the reconnection destination (e.g., gNB200-2).

[0117] (3) Signaling radio bearer Next, a signaling wireless bearer according to one embodiment will be described. Figure 14 is a diagram showing a signaling wireless bearer according to one embodiment.

[0118] As shown in Figure 14, the remote UE100-1 has an RRC layer (Uu) and a PC5 RRC layer. The RRC layer (Uu) and the PC5 RRC layer may be separate RRC entities or may be separate functions within a single RRC entity.

[0119] The RRC layer (Uu) of the remote UE100-1 transmits and receives a first RRC message used for communication control with the gNB200-1 via the relay UE100-2 on the first signaling radio bearer (SRB(A)) to the RRC layer (Uu) of the gNB200-1.

[0120] On the other hand, the PC5 RRC layer of remote UE100-1 sends and receives a second RRC message used for communication control with relay UE100-2 on a second signaling radio bearer (SRB(B)) that is different from the first signaling radio bearer, with the PC5 RRC layer of relay UE100-2. Specifically, the signaling radio bearer number of the second signaling radio bearer (SRB(B)) is different from the signaling radio bearer number of the first signaling radio bearer (SRB(A)).

[0121] By separating the signaling radio bearer in this way, it becomes easier to distinguish between the first RRC message and the second RRC message, and the first and second RRC messages can be sent and received appropriately.

[0122] Alternatively, the first signaling radio bearer and the second signaling radio bearer may be the same signaling radio bearer. In this case, the RRC layer (Uu) of the remote UE100-1 may include the first RRC message used for communication control with gNB200-1 in the second RRC message used for communication control with relay UE100-2 when sending and receiving.

[0123] (4) Measurement operation of the wireless status between the remote UE and the relay UE Next, the measurement operation of the wireless state between the remote UE100-1 and the relay UE100-2 according to one embodiment will be described.

[0124] It is possible for one remote UE100-1 to be connected to multiple relay UE100-2, or for multiple remote UE100-1s to be connected to one relay UE100-2. Therefore, it is desirable to be able to identify which remote UE100-1 and which relay UE100-2's wireless link status should be measured. The wireless status to be measured may be received power, for example RSSI (Received Signal Strength Indicator), or congestion for a predetermined frequency unit, for example CBR (Channel Busy Ratio).

[0125] Therefore, gNB200-1 receives link identification information from either remote UE100-1 or relay UE100-2 to identify the wireless link between remote UE100-1 and relay UE100-2. Based on the link identification information, gNB200-1 controls the measurement of the wireless status between remote UE100-1 and relay UE100-2.

[0126] Such link identification information can include, for example, a destination identifier that identifies the destination in sidelink communication (hereinafter referred to as the "sidelink destination identifier"). The sidelink destination identifier may also be a Destination Layer-2 ID. Such a sidelink destination identifier may also be an identifier assigned by a core network entity (ProSe function). If an adaptation layer exists, routing information may be used as link identification information. In other words, the link is identified by the route setting. When a BAP (backhaul adaptation protocol) layer is used as such an adaptation layer, the link may be identified by the Routing ID, Path ID, BAP Address, etc.

[0127] Furthermore, if the communication network between the remote UE100-1 and the relay UE100-2 is a wireless LAN, the link identification information may include an access point identifier.

[0128] (4.1) Operation Pattern 1 Figure 15 shows operation pattern 1 of the wireless status measurement operation between remote UE100-1 and relay UE100-2 according to one embodiment. In Figure 15, steps that are not essential are shown with dashed lines.

[0129] As shown in Figure 15, in step S501, the relay UE100-2 establishes an RRC connection with gNB200-1.

[0130] In step S502, the remote UE100-1 and the relay UE100-2 establish a PC5 RRC connection. Step S502 may be performed earlier than step S501.

[0131] In step S503, the remote UE100-1 establishes an RRC connection with gNB200-1.

[0132] In step S504, the relay UE100-2 transmits the sidelink destination identifier (link identification information) assigned to the relay UE100-2 to the gNB200-1.

[0133] In step S505, gNB200-1 sends an RRC message containing the measurement settings to the remote UE100-1 via relay UE100-2. These measurement settings include a sidelink destination identifier (link identification information) assigned to relay UE100-2. The measurement settings may further include trigger conditions for measurement reporting. These trigger conditions may include a threshold to be compared with the radio condition of the sidelink.

[0134] In step S506, the remote UE100-1 measures the radio status with the relay UE100-2 (i.e., the sidelink radio status) based on the measurement settings received from the gNB200-1. Specifically, the remote UE100-1 determines to perform a measurement on the relay UE100-2 based on the sidelink destination identifier (link identification information) included in the measurement settings, and performs the measurement on the relay UE100-2.

[0135] In step S507, the remote UE100-1 sends an RRC message containing the measurement report to the gNB200-1 via the relay UE100-2. The remote UE100-1 may also send an RRC message containing the measurement report when the trigger conditions set in the measurement settings are met.

[0136] The measurement report includes the measurement result from step S506 and the corresponding sidelink destination identifier (link identification information). This allows the gNB200 to identify which relay UE100-2 the measurement result corresponds to based on the sidelink destination identifier (link identification information) included in the measurement report.

[0137] (4.2) Operation Pattern 2 Figure 16 shows operation pattern 2 of the wireless status measurement operation between the remote UE100-1 and the relay UE100-2 according to one embodiment. In Figure 16, steps that are not essential are shown with dashed lines.

[0138] As shown in Figure 16, in step S601, relay UE100-2 establishes an RRC connection with gNB200-1.

[0139] In step S602, the remote UE100-1 and the relay UE100-2 establish a PC5 RRC connection. Step S602 may be performed earlier than step S601.

[0140] In step S603, the remote UE100-1 establishes an RRC connection with gNB200-1.

[0141] In step S604, the remote UE 100-1 sends the sidelink destination identifier (link identification information) assigned to the remote UE 100-1 to the gNB 200-1. The remote UE 100-1 may send the sidelink destination identifier to the gNB 200-1 in Msg3 or Msg5, or it may send the sidelink destination identifier to the gNB 200-1 in a UE auxiliary information message.

[0142] In step S605, gNB200-1 sends an RRC message containing the measurement settings to relay UE100-2. These measurement settings include a sidelink destination identifier (link identification information) assigned to remote UE100-1. The measurement settings may further include trigger conditions for measurement reporting. These trigger conditions may include a threshold to be compared with the radio condition of the sidelink.

[0143] In step S606, the relay UE100-2 measures the radio state with the remote UE100-1 (i.e., the sidelink radio state) based on the measurement settings received from gNB200-1. Specifically, the relay UE100-2 determines to perform a measurement on the remote UE100-1 based on the sidelink destination identifier (link identification information) included in the measurement settings, and performs the measurement on the remote UE100-1.

[0144] In step S607, the relay UE100-2 sends an RRC message containing the measurement report to the gNB200-1. The relay UE100-2 may also send an RRC message containing the measurement report when the trigger conditions set in the measurement settings are met.

[0145] The measurement report includes the measurement result from step S606 and the corresponding sidelink destination identifier (link identification information). This allows the gNB200 to identify which remote UE100-1 the measurement result is for based on the sidelink destination identifier (link identification information) included in the measurement report.

[0146] (Other embodiments) In the embodiments described above, the operation of the relay UE 100-2 was mainly explained, but the operation according to the embodiments described above may also be applied to the IAB (Integrated Access and Backhaul) node, which is a wireless relay node. Specifically, the IAB node may perform the operation of the relay UE 100-2 described in the embodiments described above. In such embodiments, the "relay UE" in the embodiments described above should be read as "IAB node," and the "side link" in the embodiments described above should be read as "access link." Also, the PC5 RRC connection should be read as an RRC connection with an IAB node or an RRC connection with an IAB donor.

[0147] 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.

[0148] 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).

[0149] Although the embodiments have been described in detail above with reference to the drawings, the specific configuration is not limited to those described above, and various design changes can be made without departing from the gist of the invention.

[0150] This application claims priority to Japanese Patent Application No. 2020-056518 (filed on March 26, 2020), and all of its contents are incorporated into the specification of this application.

Claims

1. A communication control method using a relay user device for relaying communication between a network node and a remote user device, The network node transmits to the remote user device first configuration information for the adaptation layer of the relay user device and second configuration information for setting the measurement of the wireless state between the remote user device and the relay user device. The network node receives a measurement report of the wireless status from the remote user device. Communication control method.

2. The second setting information includes the trigger conditions for the measurement report of the wireless status. The communication control method according to claim 1.

3. The trigger condition includes a threshold to be compared with the wireless status of the side link. The communication control method according to claim 2.

4. A remote user device that communicates with a network node via a relay user device, A receiving unit that receives from the network node first setting information for the adaptation layer of the relay user device and second setting information for setting the measurement of the wireless state between the remote user device and the relay user device, The system includes a transmitting unit that transmits a measurement report of the wireless status to the network node. Remote user device.

5. A system comprising a network node and a remote user device that communicates with the network node via a relay user device, The network node transmits to the remote user device first configuration information for the adaptation layer of the relay user device and second configuration information for setting the measurement of the wireless state between the remote user device and the relay user device. The remote user device transmits a measurement report of the wireless status to the network node. system.

6. A processor that controls a remote user device that communicates with a network node via a relay user device, A process of receiving from the network node first setting information for the adaptation layer of the relay user device and second setting information for setting the measurement of the wireless state between the remote user device and the relay user device, The process of transmitting the measurement report of the wireless status to the network node is performed. Processor.

7. A program for controlling a remote user device that communicates with a network node via a relay user device, A process of receiving from the network node first setting information for the adaptation layer of the relay user device and second setting information for setting the measurement of the wireless state between the remote user device and the relay user device, The process of transmitting the measurement report of the wireless status to the network node, and the process of causing the remote user device to perform these actions. program.

8. A network node that communicates with a remote user device via a relay user device, A transmission unit that transmits to the remote user device first setting information for the adaptation layer of the relay user device and second setting information for setting the measurement of the wireless state between the remote user device and the relay user device, The system includes a receiving unit that receives the measurement report of the wireless status from the remote user device. Network node.

Images