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 for use in a mobile communication system. [Background technology]

[0002] In a mobile communication system based on the 3GPP (3rd Generation Partnership Project) (registered trademark, the same applies below), a sidelink relay technology using a user equipment as a relay node is being considered. Sidelink relay is a technology in which a relay node called a relay user equipment (Relay UE) is involved in communication between a base station and a remote user equipment (Remote UE) and relays this communication. [Prior art documents] [Non-patent literature]

[0003] [Non-Patent Document 1] 3GPP Contribution "RP-193253", Internet<URL:https: / / www.3gpp.org / ftp / tsg_ran / TSG_RAN / TSGR_86 / Docs / RP-193253.zip> Summary of the Invention

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

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

[0006] A communication control method according to a third aspect is a method using a relay user equipment for relaying communication between a base station and a remote user equipment, the communication control method comprising: the remote user equipment transmitting and receiving a first Radio Resource Control (RRC) message used for controlling communication with the base station via the relay user equipment on a first signaling radio bearer with the base station; and the remote user equipment transmitting and receiving a second RRC message used for controlling communication with the relay user equipment with the relay user equipment on a second signaling radio bearer different from the first signaling radio bearer with the relay user equipment.

[0007] A communication control method according to a fourth aspect is a method using a relay user equipment for relaying communication between a base station and a remote user equipment, the communication control method comprising: the remote user equipment receiving a Radio Resource Control (RRC) message from the base station via the relay user equipment; and the remote user equipment performing a notification operation of notifying the relay user equipment of the content of the RRC message.

[0008] A communication control method according to a fifth aspect is a method using a relay user equipment for relaying communication between a base station and a remote user equipment, the communication control method comprising: a base station receiving, from the remote user equipment or the relay user equipment, link identification information identifying a radio link between the remote user equipment and the relay user equipment; and the base station controlling measurement of radio conditions between the remote user equipment and the relay user equipment based on the link identification information. [Brief description of the drawings]

[0009] [Figure 1] 1 is a diagram showing a configuration of a mobile communication system according to an embodiment; [Diagram 2] FIG. 1 is a diagram illustrating a configuration of a UE (user equipment) according to an embodiment. [Diagram 3] A diagram showing the configuration of a gNB (base station) according to one embodiment. [Figure 4] A diagram showing the configuration of a protocol stack of the user plane radio interface. [Diagram 5] FIG. 2 is a diagram showing the configuration of a protocol stack of the wireless interface of the control plane. [Figure 6] FIG. 1 is a diagram showing an assumed scenario in a mobile communication system according to an embodiment. [Figure 7] FIG. 1 is a diagram illustrating an example of a protocol stack in an assumed scenario according to one embodiment. [Figure 8] A diagram showing an example of a protocol stack having a PC5 RRC layer according to one embodiment. [Figure 9] FIG. 13 is a diagram illustrating another example of a protocol stack having a PC5 RRC layer according to one embodiment. [Figure 10] A diagram showing operation pattern 1 of the establishment operation of an RRC connection between a remote UE and a gNB in ​​one embodiment. [Figure 11] A figure showing operation pattern 2 of the establishment operation of an RRC connection between a remote UE and a gNB in ​​one embodiment. [Figure 12]A diagram showing operation pattern 1 regarding an RRC message from a gNB to a remote UE in one embodiment. [Figure 13] A diagram showing operation pattern 1 regarding an RRC message from a gNB to a remote UE in one embodiment. [Figure 14] FIG. 2 illustrates a signaling radio bearer according to one embodiment. [Figure 15] FIG. 11 is a diagram illustrating an operation pattern 1 of the measurement operation of the radio condition between a remote UE and a relay UE according to an embodiment. [Figure 16] FIG. 11 is a diagram illustrating an operation pattern 2 of the measurement operation of the radio condition between a remote UE and a relay UE according to an embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] The relay user equipment in the background art cannot interpret the contents of the RRC messages transmitted and received by the base station and the remote user equipment via the relay user equipment. That is, the relay user equipment is transparent from the viewpoint of the RRC connection between the base station and the remote user equipment. However, since the conventional mobile communication system does not take such a new scenario into consideration, there is a concern that the communication using the relay user equipment cannot be appropriately controlled.

[0011] Therefore, an object of the present disclosure is to enable appropriate control of communications using relay user equipment.

[0012] A mobile communication system according to an embodiment will be described with reference to the drawings. In the description of the drawings, the same or similar parts are denoted by the same or similar reference numerals.

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

[0014] As shown in FIG. 1, the 5GS1 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 mobile wireless communication device. The UE 100 may be any device that is used by a user. For example, the UE 100 is 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] The NG-RAN 10 includes a base station (called "gNB" in the 5G system) 200. The gNBs 200 are connected to each other via an 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 own cell. The gNB 200 has 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. The term "cell" is used to indicate the smallest unit of a wireless communication area. The term "cell" is also used to indicate a function or resource for wireless communication with the UE 100. One cell belongs to one carrier frequency.

[0017] In addition, gNBs can also be connected to the Evolved Packet Core (EPC), which is the core network of LTE. LTE base stations can also be connected to 5GC. LTE base stations and gNBs can also be connected via an inter-base station interface.

[0018] The 5GC20 includes an Access and Mobility Management Function (AMF) and a User Plane Function (UPF) 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 Non-Access Stratum (NAS) signaling. The UPF controls data forwarding. The AMF and the UPF are connected to the gNB 200 via an NG interface, which is an interface between a base station and a core network.

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

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

[0021] 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 a radio signal received by the antenna into a baseband signal (received signal) and outputs the baseband signal to the control unit 130.

[0022] The transmission unit 120 performs various transmissions under the control of the control unit 130. The transmission unit 120 includes an antenna and a transmitter. The transmitter converts a baseband signal (transmission signal) output by the control unit 130 into a radio signal and transmits it from the antenna.

[0023] The control unit 130 performs various controls in the UE 100. 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 in 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 baseband signals. The CPU executes programs stored in the memory to perform various processing.

[0024] Figure 3 is a diagram showing the configuration of gNB200 (base station).

[0025] As shown in FIG. 3, the gNB 200 includes a transmitter 210, a receiver 220, a control unit 230, and a backhaul communication unit 240.

[0026] The transmission unit 210 performs various transmissions under the control of the control unit 230. The transmission unit 210 includes an antenna and a transmitter. The transmitter converts a 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 a radio signal received by the antenna into a baseband signal (received signal) and outputs the baseband signal to the control unit 230.

[0028] The control unit 230 performs various controls in the gNB 200. 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 in the processing by the processor. The processor may include a baseband processor and a CPU. The baseband processor performs modulation / demodulation and encoding / decoding of baseband signals. The CPU executes programs stored in the memory to perform various processing.

[0029] The backhaul communication unit 240 is connected to adjacent base stations via an inter-base station interface. The backhaul communication unit 240 is connected to the AMF / UPF 300 via a base station-core network interface. Note that the gNB is composed of a CU (Central Unit) and a DU (Distributed Unit) (i.e., the functions are divided), and both units may be connected to each other via an F1 interface.

[0030] FIG. 4 is a diagram showing the configuration of a protocol stack of a radio interface of a user plane that handles data.

[0031] As shown in FIG. 4, the user plane radio interface protocol includes a physical (PHY) layer, a medium access control (MAC) layer, a radio link control (RLC) layer, a packet data convergence protocol (PDCP) layer, and a service data adaptation protocol (SDAP) 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 PHY layer of the UE 100 and the PHY layer of the gNB 200 via a physical channel.

[0033] The MAC layer performs data priority control, retransmission processing using hybrid ARQ (HARQ), random access procedures, etc. Data and control information are transmitted between the MAC layer of the UE 100 and the MAC layer of the gNB 200 via a transport channel. The MAC layer of the gNB 200 includes a scheduler. The scheduler determines the uplink and downlink transport format (transport block size, modulation and coding scheme (MCS)) and the resource blocks to be assigned to the UE 100.

[0034] The RLC layer transmits data to the RLC layer on the receiving side by using the functions of the MAC layer and the PHY layer. Data and control information are transmitted between the RLC layer of the UE 100 and the RLC layer of the gNB 200 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 for QoS control by the core network, to radio bearers, which are the units for QoS control by the AS (Access Stratum). Note that if the RAN is connected to the EPC, the SDAP is not necessary.

[0037] FIG. 5 is a diagram showing the configuration of a protocol stack of a radio interface of a control plane that handles signaling (control signals).

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

[0039] Between the RRC layer of the UE 100 and the RRC layer of the gNB 200, RRC signaling for various settings is transmitted. The RRC layer controls logical channels, transport channels, and physical channels in response to establishment, re-establishment, and release of radio bearers. When there is a connection (RRC connection) between the RRC of the UE 100 and the RRC of the gNB 200, the UE 100 is in RRC connected mode. When there is no connection (RRC connection) between the RRC of the UE 100 and the RRC of the gNB 200, the UE 100 is in RRC idle mode.

[0040] The NAS layer, which is located above the RRC layer, performs session management, mobility management, etc. NAS signaling is transmitted between the NAS layer of the UE 100 and the NAS layer of the AMF 300.

[0041] In addition, the UE 100 has an application layer and the like in addition to the protocol of the radio interface.

[0042] (Assumed scenario) Next, an assumed scenario in the mobile communication system 1 according to an embodiment will be described. Fig. 6 is a diagram showing an assumed scenario.

[0043] As shown in FIG. 6, a scenario is assumed in which a relay UE 100-2 is involved in communication between a gNB 200-1 and a remote UE 100-1, and sidelink relay is used to relay this communication.

[0044] The remote UE 100-1 performs wireless communication (sidelink communication) with the relay UE 100-2 over a PC5 interface (sidelink) that is an interface between UEs. The relay UE 100-2 performs wireless communication (Uu communication) with the gNB 200-1 over an NR Uu wireless interface. As a result, the remote UE 100-1 indirectly communicates with the gNB 200-1 via the relay UE 100-2. The Uu communication includes uplink communication and downlink communication.

[0045] Fig. 7 is a diagram showing an example of a protocol stack in an assumed scenario, in which the MAC layer and PHY layer, which are layers below the RLC layer, are omitted.

[0046] As shown in Fig. 7, the gNB 200-1 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 of the gNB 200-1 and the PDCP layer of the remote UE 100-1 communicate with each other via the relay UE 100-2. The RRC layer of the CU and the RRC layer of the remote UE 100-1 also communicate with each other via the relay UE 100-2. In the DU, the relay UE 100-2, and the remote UE 100-1, an adaptation layer may be provided as an upper layer of the RLC layer.

[0048] 7, the RRC layer of the CU and the RRC layer of the relay UE 100-2 communicate with each other. The PDCP layer of the CU and the PDCP layer of the relay UE 100-2 communicate with each other.

[0049] Furthermore, each of the remote UE 100-1 and the relay UE 100-2 may have an RRC layer for PC5. Such an RRC layer is called "PC5 RRC." The PC5 RRC layer of the remote UE 100-1 and the PC5 RRC layer of the relay UE 100-2 communicate with each other.

[0050] Fig. 8 is a diagram showing an example of a protocol stack having a PC5 RRC layer. Fig. 9 is a diagram showing another example of a protocol stack having a PC5 RRC layer. Figs. 8 and 9 show an example in which the gNB 200-1 is not separated into a DU and a CU, but the gNB 200-1 may be separated into a DU and a CU.

[0051] 8, the gNB 200-1 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 gNB 200-1 also has an adaptation layer between the PDCP layer (Uu) and the RLC layer (Uu).

[0052] The relay UE 100-2 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). The relay UE 100-2 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). The relay UE 100-2 also has an adaptation layer as a layer higher than the PC5 RRC layer.

[0053] The remote UE 100-1 has an RRC layer and a PDCP layer (Uu) used for communication on the Uu interface (Uu communication). The remote UE 100-1 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). The remote UE 100-1 also has an adaptation layer between the PDCP layer (Uu) and the PC5 RRC layer.

[0054] As shown in Fig. 9, the remote UE 100-1 does not need to have an adaptation layer. In the example shown in Fig. 9, the adaptation layer of the relay UE 100-2 is positioned in a layer above the RLC layer (Uu).

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

[0056] (1) Establishment of RRC connection between remote UE and gNB The operation of establishing an RRC connection between the remote UE 100-1 and the gNB 200-1 will be described.

[0057] (1.1) Operation pattern 1 This operation pattern 1 includes a step of establishing a connection between the remote UE 100-1 and the relay UE 100-2, and a step of performing a random access procedure for establishing a connection between the remote UE 100-1 and the gNB 200-1. The step of performing the random access procedure includes a proxy operation step in which the relay UE 100-2 performs at least a part of the operations performed by the MAC layer in the random access procedure on behalf of the remote UE 100-1.

[0058] As shown in Figures 8 and 9, the remote UE 100-1 has a MAC layer of the PC5 interface but does not have a MAC layer of the Uu interface. On the other hand, the random access procedure includes operations that should be performed by the MAC layer of the Uu interface. Therefore, the relay UE 100-2 performs at least a part of the operations performed by the MAC layer in the random access procedure instead of the remote UE 100-1, thereby making it possible to realize the random access procedure for establishing a connection between the remote UE 100-1 and the gNB 200-1.

[0059] Fig. 10 is a diagram showing an operation pattern 1 of the operation of establishing an RRC connection between the remote UE 100-1 and the gNB 200-1. In Fig. 10, non-essential steps are indicated by dashed lines.

[0060] As shown in Fig. 10, in step S101, the remote UE 100-1 and the relay UE 100-2 establish a PC5 RRC connection. The PC5 RRC connection refers to a connection established between the PC5 RRC layer of the remote UE 100-1 and the PC5 RRC layer of the relay UE 100-2. On the other hand, an RRC connection may not yet be established between the relay UE 100-2 and the gNB 200-1.

[0061] In addition, in the PC5 RRC connection, it may be confirmed that the relay UE 100-2 can relay traffic of the remote UE 100-1 to the gNB 200-1. For example, the remote UE 100-1 notifies the relay UE 100-2 of a relay request, and the relay UE 100-2 accepts the relay request. Then, the relay UE 100-2 permits the remote UE 100-1 to communicate the traffic to be relayed. Such a confirmation operation is also applicable to each operation pattern described later.

[0062] Prior to step S102, the remote UE 100-1 determines to perform an RRC connection establishment process with the gNB 200-1. 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) for RRC connection establishment, and provides the generated message to a lower layer. In such a case, the remote UE 100-1 usually triggers a random access procedure for the gNB 200-1. On the other hand, when the relay UE 100-2 performs relaying, the remote UE 100-1 uses the PC5 MAC entity to perform communication, and therefore does not use the Uu MAC entity. In other words, the Uu MAC entity does not need to perform the random access procedure. Therefore, the remote UE 100-1 determines not to trigger the random access procedure. In other words, when the remote UE 100-1 does not use the MAC entity associated with Uu and / or uses the MAC entity associated with PC5 where relaying is performed, at the time of RRC connection establishment (resume), it determines not to trigger the random access procedure. The remote UE 100-1 may further decide to send a proxy request message to the relay UE 100-2 to request a proxy action.

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

[0064] In step S103, the relay UE 100-2 transmits a random access preamble to the gNB 200-1 in response to the reception of the proxy request message. The random access preamble is transmitted 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 a first message (called "Msg1") in the random access procedure. Note that in step S103, the relay UE 100-2 may transmit the random access preamble to the gNB 200-1 in response to the establishment of the PC5 RRC connection (step S101) even if the relay UE 100-2 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 transmitted from the relay UE 100-2 to the remote UE 100-1.

[0065] In step S104, the gNB 200-1 transmits a random access response to the relay UE 100-2. The relay UE 100-2 receives the random access response. The random access response is transmitted from the MAC layer (Uu) of the gNB 200-1 to the MAC layer (Uu) of the relay UE 100-2. The random access response constitutes a second message (called "Msg2") in the random access procedure. The random access response includes an uplink grant indicating an uplink radio resource allocated by the gNB 200-1 to the relay UE 100-2 and a timing advance value for adjusting the uplink transmission timing of the relay UE 100-2.

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

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

[0068] The response message may be transmitted when the PC5 RRC connection is established in step S101. For example, the relay UE 100-2 may transmit the response message when the relay UE 100-2 has already established an RRC connection with the gNB 200-1 and has completed an RRC connection establishment process with the remote UE 100-1 and / or when the relay operation is performed (permitted).

[0069] In step S106, in response to receiving the response message from the relay UE 100-2, the remote UE 100-1 transmits an RRC message for the remote UE 100-1 to connect to the gNB 200-1 via the relay UE 100-2 to the gNB 200-1. Such an RRC message constitutes a third message (referred to as "Msg3") in the random access procedure. The RRC message shall be an RRC setup request message requesting establishment of an RRC connection. However, the RRC message may be an RRC re-establishment request message requesting re-establishment of an RRC connection, or an RRC recovery request message requesting recovery of an interrupted RRC connection.

[0070] In step S107, the gNB 200-1 transmits an RRC message to the remote UE 100-1 via the relay UE 100-2 in response to receiving Msg3 from the remote UE 100-1. Such an RRC message constitutes a fourth message (referred to as "Msg4") in the random access procedure. The RRC message shall be an RRC setup message. However, the RRC message may be an RRC re-establishment message or an RRC recovery message.

[0071] In step S108, in response to receiving Msg4 from the gNB 200-1, the remote UE 100-1 transmits an RRC message to the gNB 200-1 via the relay UE 100-2. Such an RRC message constitutes a fifth message (referred to as "Msg5") in the random access procedure. The RRC message shall be an RRC setup complete message. However, the RRC message may be an RRC re-establishment complete message or an RRC recovery complete message.

[0072] In step S109, an RRC connection is established (or re-established or restored) between the remote UE 100-1 and the gNB 200-1.

[0073] (1.2) Operation pattern 2 This operation pattern 2 includes a step of establishing a connection between the remote UE 100-1 and the relay UE 100-2, and a step of transmitting an RRC message from the remote UE 100-1 to the gNB 200-1 via the relay UE 100-2, for the remote UE 100-1 to connect to the gNB 200-1. The step of transmitting the RRC message includes a step of transmitting an RRC message including information indicating that the RRC message has been transmitted via the relay UE 100-2 (hereinafter, referred to as "remote information"). Here, it is assumed that the RRC message including the remote information is Msg3 or Msg5, and an example in which the remote information is included in Msg3 will be mainly described below.

[0074] As described above, the relay UE 100-2 is transparent from the viewpoint of the RRC connection between the gNB 200-1 and the remote UE 100-1, and it is difficult for the RRC layer (Uu) of the gNB 200-1 to know whether the Msg3 (or Msg5) it received was sent via the relay UE 100-2 or not. For this reason, the remote UE 100-1 transmits Msg3 (or Msg5) including remote information to the gNB 200-1, so that the gNB 200-1 can appropriately know whether the connection request is via the relay UE 100-2 or not.

[0075] In this operation pattern 2, the step of transmitting an RRC message may omit transmission and reception of a random access preamble (Msg1) and transmission and reception of a random access response (Msg2), and may include a step of transmitting an RRC message from the remote UE 100-1 to the gNB 200-1 via the relay UE 100-2. That is, unlike the above-mentioned operation pattern 1, this operation pattern 2 may not require transmission and reception of Msg1 and Msg2.

[0076] Fig. 11 is a diagram showing an operation pattern 2 of the operation of establishing an RRC connection between the remote UE 100-1 and the gNB 200-1. In Fig. 11, non-essential steps are indicated by dashed lines.

[0077] As shown in FIG. 11, in step S201, the relaying UE 100-2 establishes an RRC connection with the gNB 200-1.

[0078] In step S202, the remote UE 100-1 and the relay UE 100-2 establish a PC5 RRC connection. Step S202 may be performed before step S201.

[0079] In step S203, the remote UE 100-1 transmits an RRC message (Msg3) for the remote UE 100-1 to connect to the gNB 200-1 to the gNB 200-1 via the relay UE 100-2. Such an RRC message constitutes a third message (referred to as "Msg3") in the random access procedure. Such an RRC message shall be an RRC setup request message requesting establishment of an RRC connection. However, the RRC message may be an RRC re-establishment request message requesting re-establishment of an RRC connection, or an RRC recovery request message requesting recovery of an interrupted RRC connection.

[0080] Here, the remote UE 100-1 may transmit an RRC message (Msg3) including remote information indicating that the RRC message has been transmitted via the relay UE 100-2. The remote information may be a flag that is set to "1" when the RRC message has been transmitted via the relay UE 100-2 and to "0" otherwise. The remote information may be included in a cause field (Cause field) of the RRC message (Msg3).

[0081] The remote information may be an identifier indicating the relay UE 100-2, for example, a Cell-Radio Network Temporary Identifier (C-RNTI) of the relay UE 100-2. In this case, the C-RNTI may be notified to the remote UE 100-1 from the relay UE 100-2 in advance (for example, in S202).

[0082] In step S204, in response to receiving Msg3 from the remote UE 100-1, the gNB 200-1 transmits an RRC message (Msg4) to the remote UE 100-1 via the relay UE 100-2. Such an RRC message is assumed to be an RRC setup message. However, the RRC message may be an RRC re-establishment message or an RRC recovery message.

[0083] In step S205, in response to receiving Msg4 from the gNB 200-1, the remote UE 100-1 transmits an RRC message (Msg5) to the gNB 200-1 via the relay UE 100-2. Such an RRC message is assumed to be an RRC setup completion message. However, the RRC message may be an RRC re-establishment completion message or an RRC recovery completion message.

[0084] Here, the remote UE 100-1 may transmit an RRC message (Msg5) including remote information indicating that the RRC message has been transmitted via the relay UE 100-2. The remote UE 100-1 may transmit an RRC message (Msg5) including remote information without transmitting an RRC message (Msg3) including remote information. The remote information may be included in a cause field (Cause field) of the RRC message (Msg5).

[0085] In step S206, an RRC connection is established (or re-established or restored) between the remote UE 100-1 and the gNB 200-1.

[0086] In this manner, according to the present operation pattern 2, by transmitting an RRC message including remote information from the remote UE 100-1 via the relay UE 100-2 to the gNB 200-1, the gNB 200-1 can recognize that the connection request is via the relay UE 100-2. This allows the gNB 200-1 to appropriately control the remote UE 100-1 at the RRC layer.

[0087] For example, after establishing an RRC connection with the remote UE 100-1, the gNB 200-1 sets the timer setting values ​​of the PDCP layer and the RRC layer to be longer than the normal setting values ​​by sending an RRC reconfiguration message to the remote UE 100-1.

[0088] In addition, when the relay UE 100-2 has an adaptation layer, the gNB 200-1 may implement routing settings (e.g., binding of logical channels, etc.) of the remote UE 100-1 on the adaptation layer of the relay UE 100-2.

[0089] Furthermore, after establishing an RRC connection with the remote UE 100-1, the gNB 200-1 can appropriately configure the RLC layer (PC5), the MAC layer (PC5), and the PHY layer (PC5) by sending an RRC reconfiguration message to the remote UE 100-1 or the relay UE 100-2.

[0090] The gNB 200-1 may not include the RLC setting, MAC setting, and PHY setting of the Uu interface in the RRC reconfiguration message transmitted to the remote UE 100-1. Specifically, the gNB 200-1 that receives an RRC message including remote information does not include the PHY, MAC, and RLC setting information in the RRC reconfiguration message. On the other hand, the gNB 200-1 that receives an RRC message not including remote information includes the PHY, MAC, and RLC setting information in the RRC reconfiguration message.

[0091] (2) Operations related to RRC messages from gNB to remote UE Next, the operation regarding the RRC message from the gNB 200-1 to the remote UE 100-1 will be described.

[0092] The operation regarding the RRC message from the gNB 200-1 to the remote UE 100-1 includes a step in which the remote UE 100-1 receives the RRC message from the gNB 200-1 via the relay UE 100-2, and a step in which the remote UE 100-1 performs a notification operation to notify the relay UE 100-2 of the contents of the RRC message.

[0093] As described above, the relay UE 100-2 cannot interpret the contents of the RRC message transmitted and received by the gNB 200-1 and the remote UE 100-1 via the relay UE 100-2. Therefore, the remote UE 100-1 performs a notification operation to notify the relay UE 100-2 of the contents of the RRC message received from the gNB 200-1, so that the relay UE 100-2 can grasp the contents of the RRC message.

[0094] (2.1) Operation pattern 1 In this operation pattern 1, the RRC message that the remote UE 100-1 receives from the gNB 200-1 via the relay UE 100-2 is an RRC release message. Such an RRC release message is a message that releases or interrupts the RRC connection between the remote UE 100-1 and the gNB 200-1. In the following, an example will be described in which the RRC release message is a message that releases the RRC connection between the remote UE 100-1 and the gNB 200-1, but the RRC release message may be a message that interrupts the RRC connection. In this case, in the following description, the "release" of the RRC connection may be read as the "interruption" of the RRC connection.

[0095] Fig. 12 is a diagram showing an operation pattern 1 regarding an RRC message from the gNB 200-1 to the remote UE 100-1. In Fig. 12, non-essential steps are indicated by dashed lines.

[0096] As shown in FIG. 12, in step S301, the relaying UE 100-2 establishes an RRC connection with the gNB 200-1.

[0097] In step S302, the remote UE 100-1 and the relay UE 100-2 establish a PC5 RRC connection. Step S302 may be performed before step S301.

[0098] In step S303, the remote UE 100-1 establishes an RRC connection with the gNB 200-1.

[0099] Then, in step S304, the gNB 200-1 sends an RRC release message to the remote UE 100-1 via the relay UE 100-2.

[0100] In addition, the gNB 200-1 may include, in the RRC release message, designation information indicating whether the remote UE 100-1 should remain under the control of the relay UE 100-2. In other words, the gNB 200-1 may designate whether to maintain the PC5 RRC connection or to reselect a cell (such as the gNB 200-1). The remote UE 100-1 determines a standby operation after the RRC connection is released according to the designation information. For example, the remote UE 100-1 determines an operation that prioritizes a cell reselection operation. The priority is an operation 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 reselection decision.

[0101] In step S305, in response to receiving the RRC release message from the gNB 200-1, the remote UE 100-1 releases the RRC connection with the gNB 200-1.

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

[0103] Instead of such an explicit notification, an implicit notification may be used. The remote UE 100-1 may release the PC5 RRC connection with the relay UE 100-2 in response to receiving an RRC release message or releasing the RRC connection with the gNB 200-1. In this case, the relay UE 100-2 considers that the RRC connection with the gNB 200-1 has been released in response to the release of the PC5 RRC connection.

[0104] In step S307, in response to the notification from the remote UE 100-1, the relay UE 100-2 releases the RRC connection with the gNB 200-1.

[0105] (2.2) Operation pattern 2 In this operation pattern 2, the RRC message that the remote UE 100-1 receives from the gNB 200-1 via the relay UE 100-2 includes setting information used for communication control between the relay UE 100-2 and the gNB 200-1. The remote UE 100-1 transmits the setting information included in this RRC message to the relay UE 100-2.

[0106] Such setting information is setting information for the Uu interface. Hereinafter, such setting information is referred to as "RLC / MAC / PHY setting information of Uu." The RRC message may further include setting information used for communication control between the remote UE 100-1 and the relay UE 100-2 (i.e., setting information for the PC5 interface). This allows the gNB 200-1 to perform both the RRC reconfiguration of the remote UE 100-1 and the RRC reconfiguration of the relay UE 100-2 by a single RRC message transmitted to the remote UE 100-1.

[0107] Fig. 13 is a diagram showing an operation pattern 1 regarding an RRC message from the gNB 200-1 to the remote UE 100-1. In Fig. 13, non-essential steps are indicated by dashed lines.

[0108] As shown in FIG. 13, in step S401, the relaying UE 100-2 establishes an RRC connection with the gNB 200-1.

[0109] In step S402, the remote UE 100-1 and the relay UE 100-2 establish a PC5 RRC connection. Step S402 may be performed before step S401.

[0110] In step S403, the remote UE 100-1 establishes an RRC connection with the gNB 200-1.

[0111] Then, in step S404, the gNB 200-1 transmits an RRC message to the remote UE 100-1 via the relay UE 100-2. Such an RRC message is, for example, an RRC setup message, an RRC recovery message, an RRC re-establishment message, or an RRC reconfiguration message. The RRC message includes RLC / MAC / PHY configuration information of Uu. The RLC / MAC / PHY configuration information may include CellGroupConfig, which is configuration information indicating a cell group configuration in the Uu interface, or may include configuration information for an adaptation layer of the relay UE 100-2 (for example, routing information, etc.).

[0112] When the RRC message further includes configuration information for the PC5 interface, the remote UE 100-1 that has received the RRC message performs RRC reconfiguration in the PC5 interface using this configuration information.

[0113] In step S405, the remote UE 100-1 transmits a message including the RLC / MAC / PHY setting information of Uu contained in the RRC message to the relay UE 100-2. Such a message is transmitted from a predetermined layer of the remote UE 100-1 to a predetermined layer of the relay UE 100-2. The predetermined layer is a MAC layer (PC5), an RLC layer (PC5), a PDCP layer (PC5), a PC5 RRC layer, or an adaptation layer. The relay UE 100-2 that receives this message performs RRC reconfiguration in the Uu interface using the RLC / MAC / PHY setting information of Uu.

[0114] In step S406, the relay UE 100-2 sends an acknowledgement message (ACK) to the remote UE 100-1.

[0115] In step S407, in response to receiving the acknowledgement message (ACK), the remote UE 100-1 sends an RRC completion message to the gNB 200-1 via the relay UE 100-2. The RRC completion message is, 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] If the RRC re-establishment using the RLC / MAC / PHY setting information of Uu fails, the relay UE 100-2 may transmit a negative acknowledgement message (NACK) to the remote UE 100-1 instead of an acknowledgement message (ACK). In response to receiving the negative acknowledgement message (NACK), the remote UE 100-1 may determine that the RRC re-establishment has failed and start an RRC re-establishment process. In this RRC re-establishment process, the remote UE 100-1 may include information indicating that the RRC re-establishment in the relay UE 100-2 has failed in a Cause field in an RRC re-establishment request message transmitted to a reconnection destination (e.g., the gNB 200-2).

[0117] (3) Signaling Radio Bearer Next, a signaling radio bearer according to an embodiment will be described. Fig. 14 is a diagram showing a signaling radio bearer according to an embodiment.

[0118] 14, the remote UE 100-1 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 separate functions in one RRC entity.

[0119] The RRC layer (Uu) of the remote UE 100-1 transmits and receives a first RRC message used for controlling communication with the gNB 200-1 to and from the RRC layer (Uu) of the gNB 200-1 via the relay UE 100-2 on a first signaling radio bearer (SRB(A)).

[0120] On the other hand, the PC5 RRC layer of the remote UE 100-1 transmits and receives a second RRC message used for communication control with the relay UE 100-2 to and from the PC5 RRC layer of the relay UE 100-2 on a second signaling radio bearer (SRB(B)) different from the first signaling radio bearer. 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 dividing the signaling radio bearer in this manner, it becomes easy to distinguish the first RRC message from the second RRC message, and the first RRC message and the second RRC message can be appropriately transmitted and received.

[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 UE 100-1 may transmit and receive the first RRC message used for communication control with the gNB 200-1 in the second RRC message used for communication control with the relay UE 100-2.

[0123] (4) Measuring the radio conditions between the remote UE and the relay UE Next, a measurement operation of the radio condition between the remote UE 100-1 and the relay UE 100-2 according to an embodiment will be described.

[0124] There is a possibility that one remote UE 100-1 may be connected to multiple relay UEs 100-2, or multiple remote UEs 100-1 may be connected to one relay UE 100-2. For this reason, it is desirable to be able to specify which remote UE 100-1 and which relay UE 100-2 to measure the radio condition of the radio link between them. The radio condition to be measured may be a received power, for example, a received signal strength indicator (RSSI), or a congestion degree for each predetermined frequency unit, for example, a channel busy ratio (CBR).

[0125] For this reason, the gNB 200-1 receives link identification information that identifies a radio link between the remote UE 100-1 and the relay UE 100-2 from the remote UE 100-1 or the relay UE 100-2. The gNB 200-1 controls measurement of a radio condition between the remote UE 100-1 and the relay UE 100-2 based on the link identification information.

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

[0127] In addition, when the communication network between the remote UE 100-1 and the relay UE 100-2 is a wireless LAN, the link identification information may include an access point identifier.

[0128] (4.1) Operation pattern 1 15 is a diagram showing an operation pattern 1 of the measurement operation of the radio condition between the remote UE 100-1 and the relay UE 100-2 according to one embodiment. In FIG. 15, non-essential steps are indicated by dashed lines.

[0129] As shown in FIG. 15, in step S501, the relaying UE 100-2 establishes an RRC connection with the gNB 200-1.

[0130] In step S502, the remote UE 100-1 and the relay UE 100-2 establish a PC5 RRC connection. Step S502 may be performed before step S501.

[0131] In step S503, the remote UE 100-1 establishes an RRC connection with the gNB 200-1.

[0132] In step S504, the relaying UE 100-2 transmits a sidelink destination identifier (link identification information) assigned to the relaying UE 100-2 to the gNB 200-1.

[0133] In step S505, the gNB 200-1 transmits an RRC message including a measurement configuration to the remote UE 100-1 via the relay UE 100-2. The measurement configuration includes a sidelink destination identifier (link specific information) assigned to the relay UE 100-2. The measurement configuration may further include a trigger condition for a measurement report. The trigger condition may include a threshold to be compared with the radio condition of the sidelink.

[0134] In step S506, the remote UE 100-1 measures a radio state with the relay UE 100-2 (i.e., a radio state of a sidelink) based on the measurement configuration received from the gNB 200-1. Specifically, the remote UE 100-1 determines to perform measurement for the relay UE 100-2 based on a sidelink destination identifier (link identification information) included in the measurement configuration, and performs measurement for the relay UE 100-2.

[0135] In step S507, the remote UE 100-1 transmits an RRC message including the measurement report to the gNB 200-1 via the relay UE 100-2. The remote UE 100-1 may transmit the RRC message including the measurement report in response to a trigger condition set in the measurement configuration being satisfied.

[0136] The measurement report includes the measurement result in step S506 and a sidelink destination identifier (link identification information) corresponding to the measurement result. This allows the gNB 200 to identify which relay UE 100-2 the measurement result is for, based on the sidelink destination identifier (link identification information) included in the measurement report.

[0137] (4.2) Operation pattern 2 16 is a diagram showing an operation pattern 2 of the measurement operation of the radio condition between the remote UE 100-1 and the relay UE 100-2 according to one embodiment. In FIG. 16, non-essential steps are indicated by dashed lines.

[0138] As shown in FIG. 16, in step S601, the relaying UE 100-2 establishes an RRC connection with the gNB 200-1.

[0139] In step S602, the remote UE 100-1 and the relay UE 100-2 establish a PC5 RRC connection. Step S602 may be performed before step S601.

[0140] In step S603, the remote UE 100-1 establishes an RRC connection with the gNB 200-1.

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

[0142] In step S605, the gNB 200-1 transmits an RRC message including a measurement configuration to the relay UE 100-2. The measurement configuration includes a sidelink destination identifier (link specific information) assigned to the remote UE 100-1. The measurement configuration may further include a trigger condition for a measurement report. The trigger condition may include a threshold to be compared with the radio condition of the sidelink.

[0143] In step S606, the relaying UE 100-2 measures a radio state with the remote UE 100-1 (i.e., a radio state of a sidelink) based on the measurement configuration received from the gNB 200-1. Specifically, the relaying UE 100-2 determines to perform measurement for the remote UE 100-1 based on a sidelink destination identifier (link identification information) included in the measurement configuration, and performs measurement for the remote UE 100-1.

[0144] In step S607, the relay UE 100-2 transmits an RRC message including the measurement report to the gNB 200-1. The relay UE 100-2 may transmit the RRC message including the measurement report in response to the trigger condition set in the measurement configuration being satisfied.

[0145] The measurement report includes the measurement result in step S606 and a sidelink destination identifier (link identification information) corresponding to the measurement result. This allows the gNB 200 to identify which remote UE 100-1 the measurement result is for, based on the sidelink destination identifier (link identification information) included in the measurement report.

[0146] (Other embodiments) In the above-mentioned embodiment, the operation in the relay UE 100-2 has been mainly described, but the operation according to the above-mentioned embodiment may be applied to an 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 above-mentioned embodiment. In such an embodiment, the "relay UE" in the above-mentioned embodiment may be replaced with the "IAB node", and the "side link" in the above-mentioned embodiment may be replaced with the "access link". Also, the PC5 RRC connection may be replaced with the RRC connection with the IAB node or the RRC connection with the IAB donor.

[0147] A program may be provided that causes a computer to execute each process performed by the UE 100 or the gNB 200. The program may be recorded in a computer-readable medium. Using the computer-readable medium, it is possible to install the program in the 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, and may be, for example, a recording medium such as a CD-ROM or a DVD-ROM.

[0148] In addition, circuits that execute each process performed by UE100 or gNB200 may be integrated, and at least a part of UE100 or gNB200 may be configured as a semiconductor integrated circuit (chip set, SoC).

[0149] The above describes the embodiments in detail with reference to the drawings, but the specific configuration is not limited to that described above, and various design changes, etc. are possible without departing from the spirit of the invention.

[0150] This application claims priority to Japanese Patent Application No. 2020-056518 (filed March 26, 2020), the entire contents of which are incorporated herein by reference.

Claims

1. 1. A method of communication control using a relay user equipment for relaying communication between a network node and a remote user equipment, comprising: said network node transmitting to said remote user equipment configuration information for configuring measurements of radio conditions between said remote user equipment and said relay user equipment; receiving, by the network node, the radio condition measurement report from the remote user equipment. Communications control method.

2. The setting information includes a trigger condition for reporting the measurement of the radio condition. The communication control method according to claim 1 .

3. The trigger condition includes a threshold to be compared with the sidelink radio conditions. The communication control method according to claim 2.

4. A remote user equipment (UE) communicating with a network node via a relay user equipment (REE), comprising: a receiving unit for receiving configuration information from the network node for configuring measurements of radio conditions between the remote user equipment and the relay user equipment; a transmitter for transmitting the measurement report of the radio conditions to the network node. Remote user equipment.

5. 1. A system comprising a network node and a remote user equipment communicating with said network node via a relay user equipment, comprising: the network node transmits to the remote user equipment configuration information for configuring measurements of radio conditions between the remote user equipment and the relay user equipment; The remote user equipment transmits the radio condition measurement report to the network node. system.

6. A processor for controlling a remote user equipment (UE) communicating with a network node via a relay user equipment (UE), receiving configuration information from the network node for configuring measurements of radio conditions between the remote user equipment and the relay user equipment; and transmitting the radio condition measurement report to the network node. Processor.

7. 1. A program for controlling a remote user equipment (UE) communicating with a network node via a relay user equipment (UE), comprising: receiving configuration information from the network node for configuring measurements of radio conditions between the remote user equipment and the relay user equipment; and transmitting the radio condition measurement report to the network node. program.

8. A network node for communicating with a remote user equipment via a relay user equipment, comprising: a transmitter for transmitting configuration information to the remote user equipment for configuring measurement of a radio condition between the remote user equipment and the relay user equipment; a receiving unit for receiving the radio condition measurement report from the remote user equipment. Network node.

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