Communication control method, remote user device, and relay device

Abstract

One aspect relates to a communication control method for a mobile communication system in which communication is performed between remote user equipment and a base station via first relay user equipment. The communication control method comprises a step of the first relay user equipment transmitting, to the remote user equipment, first slice support information including a network slice that the first relay user equipment can support. Further, the communication control method comprises a step of the remote user equipment performing a reselection process for re-selecting, on the basis of the first slice support information, relay user equipment that supports a desired network slice of which utilization is desired by the remote user equipment.

Description

[Technical Field]

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

[0002] In mobile communication systems based on 3GPP (3rd Generation Partnership Project) standards, a sidelink relay technology using a user device as a relay node is being studied (see, for example, "3GPP TS 38.300 V16.8.0(2021-12)"). Sidelink relay is a technology in which a relay node called a relay user device (Relay UE) intervenes in communication between a base station and a remote user device (Remote UE) and relays this communication. Summary of the Invention

[0003] A communication control method according to a first aspect is a communication control method in a mobile communication system in which communication is performed between a remote user equipment (UE) and a base station via a first relay user equipment (RUE). The communication control method includes a step in which the first relay user equipment (UE) transmits, to the remote user equipment, first slice support information including a network slice that the first relay user equipment (UE) can support. The communication control method also includes a step in which the remote user equipment (UE) performs a reselection process to reselect a relay user equipment (UE) that supports a desired network slice that the remote user equipment (UE) desires to use, based on the first slice support information.

[0004] A communication control method according to a second aspect is a communication control method in a mobile communication system in which communication is performed between a remote user equipment (UE) and a base station via a relay user equipment (UE). The communication control method includes a step in which the base station transmits mapping information indicating a correspondence relationship between a network slice and a resource pool to the relay user equipment. The communication control method also includes a step in which the relay user equipment transmits the mapping information to the remote user equipment. The communication control method further includes a step in which the remote user equipment and the relay user equipment perform communication using the resource pool based on the mapping information.

[0005] A communication control method according to a third aspect is a communication control method in a mobile communication system in which communication is performed between a remote user equipment (UE) and a base station via a first relay user equipment (RUE). The communication control method includes a step in which the remote user equipment (UE) transmits a connection request message to the first relay user equipment (UE) for establishing a connection to the first relay user equipment. The communication control method also includes a step in which the remote user equipment (UE) transmits a predetermined message to the first relay user equipment (UE) for establishing a connection to the base station in the first relay user equipment. The communication control method further includes a step in which the first relay user equipment (UE) performs a random access procedure with the base station using a RACH resource associated with an identifier of a network slice included in either the connection request message or the predetermined message. [Brief explanation of the drawings]

[0006] [Figure 1] FIG. 1 is a diagram showing an example of the configuration of a mobile communication system 1 according to the first embodiment. [Figure 2] FIG. 2 is a diagram illustrating an example of the configuration of a UE according to the first embodiment. [Figure 3] FIG. 3 is a diagram illustrating an example of the configuration of a gNB according to the first embodiment. [Figure 4] FIG. 4 is a diagram illustrating an example of the configuration of a protocol stack of a user plane according to the first embodiment. [Figure 5]FIG. 5 is a diagram illustrating an example of the configuration of a protocol stack of a control plane according to the first embodiment. [Figure 6] FIG. 6 is a diagram illustrating an assumed scenario according to the first embodiment. [Figure 7] FIG. 7 is a diagram illustrating an example of the configuration of a protocol stack of a user plane in an assumed scenario according to the first embodiment. [Figure 8] FIG. 8 is a diagram illustrating an example of the configuration of a protocol stack of a control plane in an assumed scenario according to the first embodiment. [Figure 9] FIG. 9 is a diagram illustrating an example of operation according to the first embodiment. [Figure 10] FIG. 10 is a diagram illustrating an example of operation according to a modified example of the first embodiment. [Figure 11] FIG. 11 is a diagram illustrating an example of resource pool allocation according to the second embodiment. [Figure 12] FIG. 12 is a diagram illustrating an example of operation according to the second embodiment. [Figure 13] FIG. 13 is a diagram illustrating an example of operation according to the third embodiment. [Figure 14] FIG. 14 is a diagram illustrating an example of operation according to a modified example of the third embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0007] 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.

[0008] (Example of a mobile communication system configuration) An example of the configuration of a mobile communication system according to one embodiment will be described. The mobile communication system 1 according to one embodiment is a 3GPP 5G system. Specifically, the radio access method in the mobile communication system 1 is NR (New Radio), which is a 5G radio access method. However, LTE (Long Term Evolution) may be applied at least partially to the mobile communication system 1. Furthermore, future mobile communication systems such as 6G may also be applied to the mobile communication system 1.

[0009] FIG. 1 is a diagram showing an example of the configuration of a mobile communication system 1 according to an embodiment.

[0010] As shown in FIG. 1, the mobile communication system 1 includes a user equipment (UE) 100, a 5G radio access network (NG-RAN) 10, and a 5G core network (5GC) 20.

[0011] 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 may be a mobile phone terminal (including a smartphone), a tablet terminal, a laptop 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), or an aircraft or a device provided in an aircraft (Aerial UE).

[0012] The NG-RAN 10 includes a base station (called a "gNB" in a 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 a 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 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 that performs wireless communication with a UE 100. One cell belongs to one carrier frequency. In the following, the term "cell" and a base station may be used interchangeably.

[0013] In addition, the gNB200 can also be connected to the EPC (Evolved Packet Core), which is the LTE core network. The LTE base station can also be connected to the 5GC20. The LTE base station and the gNB200 can also be connected via an inter-base station interface.

[0014] 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 UPF 300 are connected to the gNB 200 via an NG interface, which is an interface between a base station and a core network.

[0015] (Configuration of user device) Next, a configuration example of the UE 100, which is a user equipment according to an embodiment, will be described. FIG.

[0016] As shown in FIG. 2, the UE 100 includes a receiving unit 110, a transmitting unit 120, and a control unit .

[0017] 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 converts (down-converts) a radio signal received by the antenna into a baseband signal (received signal) and outputs the baseband signal to the control unit 130.

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

[0019] The control unit 130 performs various controls in the UE 100. The control unit 130 includes at least one memory and at least one processor electrically connected to the memory. The memory stores programs executed by the processor and information used in 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 processes. Note that the control unit 130 may perform each process and / or each operation in the UE 100 in each of the embodiments described below.

[0020] (Base station configuration example) Next, a configuration example of the gNB 200, which is a base station according to an embodiment, will be described. Fig. 3 is a diagram illustrating a configuration example of the gNB 200.

[0021] As shown in FIG. 3, the gNB 200 has a transmitter 210, a receiver 220, a controller 230, and a backhaul communication unit 240.

[0022] The transmitter 210 performs various transmissions under the control of the controller 230. The transmitter 210 includes an antenna, and converts (up-converts) a baseband signal (transmission signal) output by the controller 230 into a radio signal and transmits it from the antenna.

[0023] 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 converts (down-converts) a radio signal received by the antenna into a baseband signal (received signal) and outputs the baseband signal to the control unit 230.

[0024] 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 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 processes. Note that the control unit 230 may perform each process and / or each operation in the gNB 200 in each of the embodiments described below.

[0025] The backhaul communication unit 240 is connected to neighboring base stations via an Xn interface. The backhaul communication unit 240 is connected to the AMF and UPF 300 via an NG interface. Note that the gNB 200 is configured (i.e., functionally divided) with a CU (Central Unit) and a DU (Distributed Unit), and both units may be connected via an F1 interface.

[0026] (Example of protocol stack configuration) FIG. 4 is a diagram showing an example of the configuration of a protocol stack of a radio interface of a user plane that handles data.

[0027] 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. Note that hereinafter, the terms "layer" and "entity" may be used interchangeably.

[0028] 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.

[0029] The MAC layer performs data priority control, retransmission processing using Hybrid Automatic Repeat reQuest (HARQ), random access procedures, etc. Data and control information are transmitted between the MAC layer of UE100 and the MAC layer of gNB200 via transport channels. The MAC layer of gNB200 includes a scheduler, which determines the uplink and downlink transport format (transport block size, modulation and coding scheme (MCS)) and the resource blocks to be allocated to UE100.

[0030] The RLC layer transmits data to the RLC layer on the receiving side using the functions of the MAC layer and 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 logical channels.

[0031] The PDCP layer performs header compression / decompression and encryption / decryption.

[0032] The SDAP layer maps IP flows, which are the units for Quality of Service (QoS) control by the core network, to radio bearers, which are the units for QoS control by the Access Stratum (AS). Note that if the RAN is connected to the EPC, SDAP is not necessary.

[0033] 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).

[0034] 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.

[0035] RRC signaling for various settings is transmitted between the RRC layer of UE100 and the RRC layer of gNB200. The RRC layer controls logical channels, transport channels, and physical channels according to the establishment, re-establishment, and release of radio bearers. When there is a connection (RRC connection) between the RRC of UE100 and the RRC of gNB200, UE100 is in an RRC connected state. When there is no connection (RRC connection) between the RRC of UE100 and the RRC of gNB200, UE100 is in an RRC idle state. When the RRC connection is interrupted (suspended), UE100 is in an RRC inactive state.

[0036] The NAS layer, which is positioned 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.

[0037] The UE 100 has an application layer and the like in addition to the radio interface protocol.

[0038] [First embodiment] Next, a first embodiment will be described.

[0039] (Assumed scenario) Here, an assumed scenario in the mobile communication system 1 according to the first embodiment will be described. Fig. 6 is a diagram showing an assumed scenario.

[0040] As shown in Fig. 6, a scenario is assumed in which a relay UE 100-2 is interposed in communication between a gNB 200-1 and a remote UE 100-1, and sidelink relay is used to relay this communication. In other words, this is a scenario in which the gNB 200-1 and the remote UE 100-1 communicate via the relay UE 100-2.

[0041] The remote UE 100-1 performs wireless communication (sidelink communication) with the relay UE 100-2 over a PC5 interface (sidelink), which is an interface between UEs. The relay UE 100-2 performs wireless communication (Uu communication) with the gNB 200-1 over an NR Uu 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.

[0042] (Example of protocol stack configuration in assumed scenario) Next, an example of the configuration of a protocol stack in a hypothetical scenario will be described.

[0043] Fig. 7 is a diagram illustrating an example of a user plane protocol stack in an assumed scenario. Fig. 7 is also an example of a user plane protocol stack in relaying via a relay UE 100-2 (i.e., U2N (UE to Network) relaying).

[0044] Fig. 8 shows an example of a protocol stack of the control plane in the assumed scenario. Fig. 8 is also an example of a protocol stack of the control plane in U2N relay.

[0045] As shown in Figure 7, gNB200-1 has a Uu-SRAP (Sidelink Relay Adaptation Protocol) layer, a Uu-RLC layer, a Uu-MAC layer, and a Uu-PHY layer used for communication (Uu communication) on the NR Uu interface.

[0046] The relay UE 100-2 has a Uu-SRAP layer, a Uu-RLC layer, a Uu-MAC layer, and a Uu-PHY layer used for communication on the NR Uu interface (Uu communication). Also, the relay UE 100-2 has a PC5-SRAP layer, a PC5-RLC layer, a PC5-MAC layer, and a PC5-PHY layer used for communication on the PC5 interface (PC5 communication).

[0047] The remote UE 100-1 has a Uu-SDAP layer and a Uu-PDCP layer used for communication (Uu) on the Uu interface, and also has a PC5-SRAP layer, a PC5-RLC layer, a PC5-MAC layer, and a PC5-PHY layer used for communication (PC5 communication) on the PC5 interface.

[0048] As shown in FIG. 8, in the control plane, a Uu-RRC layer is arranged in place of the Uu-SDAP layer of the user plane.

[0049] As shown in Figures 7 and 8, an SRAP layer is arranged on the Uu interface and the PC5 interface. The SRAP layer is an example of a so-called adaptation layer. The SRAP layer exists only in Layer 2 relay and does not exist in Layer 3 relay. The SRAP layer also exists in all of the remote UE 100-1, relay UE 100-2, and gNB 200-1. Furthermore, there are two SRAP layers: PC5-SRAP and Uu-SRAP. The PC5-SRAP and Uu-SRAP have a bearer mapping function. For example, they have the following bearer mapping function. That is, the Uu-SRAP of the remote UE 100-1 and the gNB 200-1 maps the bearer (Uu-PDCP) to the PC5 RLC channel (PC5-RLC). Furthermore, the PC5-SRAP and Uu-SRAP of the relay UE 100-2 perform mapping between the PC5 RLC channel (PC5-RLC) and the Uu RLC channel (Uu-RLC). Furthermore, the Uu-SRAP has a function of identifying the remote UE 100-1.

[0050] 7 and 8, 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 a "PC5-RRC layer." There is a one-to-one correspondence between the PC5-RRC connection and the PC5 unicast link between the remote UE 100-1 and the relay UE 100-2, and the PC5-RRC connection is established after the PC5 unicast link is established.

[0051] 7 and 8, each of the remote UE 100-1 and the relay UE 100-2 may have a PC5-S (Signaling) protocol layer. The PC5-S protocol layer is a layer above the PDCP layer. Like the PC5-RRC layer, the PC5-S protocol layer is also a layer for transmitting control information.

[0052] (Communication control method in the first embodiment) Next, a communication control method in the first embodiment will be described. In the first embodiment, relay reselection that takes network slicing into consideration in an assumed scenario will be described. Such relay reselection is called "slice-specific relay reselection."

[0053] In describing slice-specific relay station reselection, first, an overview of network slicing will be described. Next, slice-specific cell reselection will be described. Then, relay station reselection will be described. After that, slice-specific relay station reselection according to the first embodiment will be described.

[0054] (Network Slicing) Network slicing is a technology that creates multiple virtual networks by virtually dividing a physical network constructed by a carrier (for example, a network consisting of NG-RAN10 and 5GC20). Each virtual network is called a network slice. In the following, a network slice may be simply referred to as a "slice."

[0055] Each slice is provided with a slice identifier that identifies the slice. An example of a slice identifier is S-NSSAI (Single Network Slice Selection Assistance Information). S-NSSAI includes an 8-bit SST (slice / service type). S-NSSAI may further include a 24-bit SD (slice differentiator). SST is information indicating the service type to which the slice is associated. SD is information for differentiating multiple slices associated with the same service type. Information including multiple S-NSSAIs is called NSSAI (Network Slice Selection Assistance Information).

[0056] One or more slices may be grouped to form a slice group. A slice group is a group including one or more slices, and a slice group identifier is assigned to the slice group. The slice group may be configured by a core network (e.g., AMF 300) or a radio access network (e.g., gNB 200-1). The configured slice group may be notified to UE 100.

[0057] Hereinafter, the term "slice" or "slicing" may refer to an S-NSSAI, which is an identifier of a single slice, or an NSSAI, which is a collection of S-NSSAIs. The term "slice" or "slicing" may also refer to a slice group, which is a group of one or more S-NSSAIs or NSSAIs.

[0058] Furthermore, the UE 100 determines a desired slice that the UE 100 wishes to use. Such a desired slice may be called an "intended slice."

[0059] 3GPP is currently discussing RAN slicing, which considers network slicing at the RAN level. For example, RAN slicing is expected to enable slice-based radio resource allocation and slice-based Quality of Service (QoS) implementation.

[0060] (slice-specific cell reselection) Next, slice-specific cell reselection will be described.

[0061] In 3GPP, discussions are underway on introducing slice-specific cell reselection in RAN slicing. Slice-specific cell reselection is a process performed by UE 100 in an RRC idle state or an RRC inactive state to transition from a current serving cell (e.g., cell #1) to a neighboring cell (e.g., cell #2) as it moves.

[0062] Slice-specific cell reselection is performed using slice frequency information received from or stored in the network, which includes, for each slice (or slice group), the frequency (or frequencies) supporting the slice and the frequency priority assigned to each frequency.

[0063] In slice-specific cell reselection, the following process is performed:

[0064] First, the NAS of the UE 100 notifies the AS of slice information including slice identifiers of desired slices of the UE 100 and slice priorities of each desired slice. The "desired slice" refers to the intended slice described above, and includes a slice likely to be used, a candidate slice, a desired slice, a slice desired for communication, a requested slice, an allowed slice, or an intended slice.

[0065] Secondly, the AS of the UE 100 rearranges the slices (or slice identifiers) notified from the NAS in descending order of slice priority.

[0066] Third, the AS of the UE 100 selects one slice in descending order of slice priority, and assigns frequency priorities to the frequencies associated with the selected slice for the selected slice. The AS of the UE 100 assigns frequency priorities based on slice frequency information.

[0067] Fourth, the AS of the UE 100 selects one frequency in descending order of frequency priority for the selected slice, and performs measurement processing on the selected frequency.

[0068] Fifth, the AS of the UE 100 identifies the highest-ranked cell based on the measurement result and determines whether the cell can provide the selected slice. This determination is made based on previously received (or stored) cell information. The cell information may include information indicating a correspondence relationship between cells (e.g., a serving cell and each neighboring cell) and slices that the cell does or does not provide.

[0069] Sixth, if the AS of UE 100 determines that the cell with the highest rank provides the selected slice, the AS of UE 100 reselects the cell with the highest rank and camps on the cell. On the other hand, if the AS of UE 100 determines that the cell with the highest rank cannot provide the selected slice, it selects a frequency with the next highest frequency priority, performs measurement processing on the frequency, and repeats the above-mentioned processing. When there is no frequency for performing measurement processing on the selected slice, the AS of UE 100 selects a selected slice with the next highest slice priority and repeats the above-mentioned processing on the selected slice.

[0070] As a result, for example, the UE 100 can preferentially reselect a cell that supports a desired slice desired by the UE 100, and can appropriately communicate in the cell.

[0071] (relay reselection) Next, relay station reselection will be described.

[0072] In 3GPP, introduction of relay reselection in sidelink relay is under discussion. Relay reselection is performed, for example, when a UE 100 in an RRC idle state or an RRC inactive state moves from a current relay UE (e.g., relay UE #1) to another relay UE (e.g., relay UE #2).

[0073] The remote UE 100-1 may reselect a relay station when the frequency used for sidelink communication goes out of coverage. The remote UE 100-1 may also reselect a relay station when the RSRP measurement value of the cell on which the remote UE 100-1 is camped falls below a predetermined threshold. The remote UE 100-1 selects a relay UE whose SD-RSRP (Sidelink Discovery Reference Signal Received Power) exceeds a minimum received RSRP level (minimum reception quality level) as a candidate relay UE. The remote UE 100-1 may select, as a relay UE for reselection, a candidate relay UE with the highest quality of the radio link (i.e., PC5 unicast link) from among all candidate relay UEs that satisfy a predetermined criterion. The remote UE 100-1 then reselects the relay UE and camps on it.

[0074] Note that a similar process may be performed for relay selection.

[0075] (Slice-specific relay reselection according to the first embodiment) The above-described relay reselection does not take slices into consideration. Therefore, for example, the UE 100 does not necessarily reselect a relay UE 100-2 that supports a desired slice through relay reselection. Therefore, in an assumed scenario, appropriate communication may not be performed.

[0076] Also, the slice-specific cell reselection mentioned above, although it takes cells into account, may not necessarily work properly in the expected scenario of sidelink relaying.

[0077] Therefore, in the first embodiment, relay station reselection that takes slices into consideration (that is, slice-specific relay station reselection) will be described in an assumed scenario.

[0078] Specifically, first, a first relay user equipment (e.g., relay UE 100-2) transmits first slice support information including a network slice that can be supported by the first relay user equipment to a remote user equipment (e.g., remote UE 100-1). Second, the remote user equipment performs a reselection process to reselect a relay user equipment that supports a desired network slice (e.g., an intended slice) that the remote user equipment desires to use based on the first slice support information.

[0079] This allows the remote UE 100-1 to reselect the relay UE 100-2 that supports the desired slice, and enables appropriate communication via sidelink relay.

[0080] (Operation example according to the first embodiment) Fig. 9 is a diagram illustrating an example of operation according to the first embodiment. Fig. 9 illustrates a procedure for slice-specific relay reselection.

[0081] Note that the remote UE 100-1 is in an RRC idle state or an RRC inactive state during the operation shown in Fig. 9. The PC5 connection between the remote UE 100-1 and the relay UE 100-2 may be disconnected or may be connected by a PC5 connection. The relay UE 100-2 may be in an RRC connected state, an RRC idle state, or an RRC inactive state during the operation shown in Fig. 9.

[0082] As shown in Fig. 9, in step S10, the relay UE 100-2 may request the serving cell of the gNB 200-1 to provide information indicating slices supported by the serving cell (hereinafter, this may be referred to as "cell supported slice information"). Step S10 may be a step in which a predetermined layer of the relay UE 100-2 transmits a message of the predetermined layer including the request to a predetermined layer of the gNB 200-1. The predetermined layer may be any one of the Uu-PHY layer, the Uu-MAC layer, the Uu-RLC layer, and the Uu-SRAP layer in the Uu link.

[0083] In step S11, the relay UE 100-2 identifies slices supported by the serving cell. The relay UE 100-2 may identify slices supported by the serving cell from configuration information for slice-specific cell reselection or RACH provided by the serving cell. The configuration information may be included in a system information block (SIB) broadcast from the serving cell. Alternatively, the configuration information may be included in an RRC release (RRCRelease) message unicast transmitted from the serving cell. Alternatively, the relay UE 100-2 may identify slices supported by the serving cell from cell-supported slice information provided by the serving cell. The cell-supported slice information may be transmitted as dedicated signaling unicast transmitted from the serving cell.

[0084] The serving cell of the gNB 200-1 may transmit QoS configuration information indicating the QoS for each slice to the relay UE 100-2 as dedicated signaling. The relay UE 100-2 can determine, for each slice, whether or not each slice has a sufficient capacity to satisfy the QoS requirements, based on the QoS configuration information. The serving cell may transmit the QoS configuration information to the relay UE 100-2 in response to a request from the relay UE 100-2.

[0085] In step S12, the relay UE 100-2 identifies slices that it can support. The relay UE 100-2 may identify the slices identified in step S11 (i.e., slices supported by the serving cell) as slices that it can support. In addition, the relay UE 100-2 may identify slices that it can support based on its own radio resource usage status, hardware load status, congestion status of the Uu link and / or PC5 unicast link, and QoS setting information.

[0086] In step S13, the relay UE 100-2 may transmit information indicating the slices that the relay UE 100-2 can support, which was identified in step S12 (hereinafter, may be referred to as "supportable slice information"), to the gNB 200-1. The supportable slice information may be transmitted by being included in a message of a predetermined layer.

[0087] In step S14, the relay UE 100-2 may identify slices supported by neighboring relay UEs (e.g., second relay user equipment) neighboring the relay UE 100-2. In this case, the serving cell of the gNB 200-1 has acquired the slices supported by the neighboring relay UEs in step S13 or the like, and therefore can transmit information indicating the slices supported by the neighboring relay UEs (hereinafter, sometimes referred to as "neighboring relay UE slice support information") to the relay UE 100-2. The neighboring relay UE slice support information may be transmitted in a message included in a predetermined layer.

[0088] In step S15, the relay UE 100-2 transmits slice support information (first slice support information) to the remote UE 100-1. Here, the relay UE 100-2 transmits information indicating which slices the relay UE 100-2 can support to the remote UE 100-1. The relay UE 100-2 may transmit a discovery message including the slice support information. Alternatively, the relay UE 100-2 may transmit a PC5-RRC message including the slice support information. Alternatively, the relay UE 100-2 may transmit a PC5-S message including the slice support information.

[0089] The slice support information includes an identifier of a slice that can be supported by the relay UE 100-2. The supportable slice may be the slice identified in step S12. The slice support information may include an identifier of a slice supported by a neighboring relay UE. The slice supported by a neighboring relay UE may be the slice identified in step S14. The slice support information including the identifier may be neighboring relay UE slice support information (second slice support information). The second slice support information may be included in the first slice support information and transmitted as the first slice support information, or the first slice support information and the second slice support information may be transmitted separately.

[0090] In the example shown in FIG. 9, the slice support information is transmitted from one relay UE 100-2, but slice support information may be transmitted from multiple relay UEs. Each of the multiple relay UEs provides the remote UE 100-1 with information on which slices it can support. In this case, the remote UE 100-1 reselects a relay UE that supports a desired slice from among the multiple relay UEs based on the slice support information in a later process.

[0091] In step S16, the AS of the remote UE 100-1 is notified of the intended slices from the upper layer (NAS). The desired slices may include priority information for each desired slice.

[0092] In step S17, the remote UE 100-1 identifies a desired slice (with the highest priority) and identifies relay UEs that support the desired slice. In step S17, the remote UE 100-1 determines which relay UEs support the desired slice. The relay UEs identified in this manner may be referred to as "specific relay UEs." The remote UE 100-1 identifies the specific relay UEs based on the slice support information. The remote UE 100-1 may identify multiple specific relay UEs.

[0093] In step S18, the remote UE 100-1 performs a process of increasing the priority of the specific relay UE.

[0094] For example, as a process of increasing the priority, the remote UE 100-1 may add an offset value to a radio measurement value (such as SD-RSRP or SL-RSRP (Sidelink Reference Signal Received Power)) of the relaying UE. The offset value may be notified from the relaying UE 100-2. Alternatively, the offset value may be notified from the gNB 200-1. The notification from the relaying UE 100-2 may be transmitted in a state of being included in a message of a predetermined layer. 、g The notification from the NB 200-1 may be transmitted in a message of the Uu-RRC layer. Alternatively, the offset value may be determined by the NB 200-1 itself (implementation dependent). Note that the remote UE 100-1 may set only the relay UE as a reselection candidate.

[0095] In step S19, the remote UE 100-1 executes a relay station reselection process. For example, the remote UE 100-1 performs the following process. That is, the remote UE 100-1 acquires radio measurement values ​​for surrounding relay UEs. The remote UE 100-1 adds an offset value to the radio measurement values ​​of a specific relay UE. The remote UE 100-1 selects a relay UE whose radio measurement values ​​exceed a minimum radio quality level as a candidate relay UE. The remote UE 100-1 may select a relay UE that satisfies a predetermined criterion (for example, has the highest radio measurement value) from the candidate relay UEs. The remote UE 100-1 may set the selected relay UE as a suitable relay UE. Since the radio measurement values ​​of the specific relay UE are given a higher priority in step S18, the specific relay UE is more likely to be selected as a suitable relay UE in the relay station reselection process.

[0096] In step S20, the remote UE 100-1 determines whether the relay reselection is successful. If the relay reselection is successful in step S20 (YES in step S20), the process proceeds to step S21. On the other hand, if the relay reselection is not successful in step S20 (NO in step S20), the process proceeds to step S17 again.

[0097] Whether relay reselection is successful or not depends on whether remote UE 100-1 can select an appropriate relay UE. If remote UE 100-1 can select an appropriate relay UE, remote UE 100-1 may determine that relay reselection is successful (YES in step S20). On the other hand, if remote UE 100-1 cannot select an appropriate UE because there is no relay UE that supports the desired slice or the radio measurement value is lower than the minimum radio quality level, remote UE 100-1 may determine that relay reselection is not successful (NO in step S20).

[0098] When the process returns to step S17, the remote UE 100-1 repeats the above-described process by selecting a relay UE supporting the desired slice with the next highest priority as a specific relay UE in step S17. If the remote UE 100-1 selects a relay UE supporting the desired slice with the lowest priority as a specific relay UE but the relay reselection is unsuccessful, the remote UE 100-1 may not perform reselection by slice-specific relay station reselection.

[0099] In step S21, the remote UE 100-1 reselects a relay UE that supports the desired slice and camps on the relay UE.

[0100] For example, a scenario may be considered in which the serving cell of the gNB 200-1 does not provide a target slice for the remote UE 100-1. However, as described above, by performing a slice-specific relay reselection procedure, the remote UE 100-1 can indirectly connect to a cell providing the target slice via a relay UE (reselected relay UE) camped on the cell, thereby accessing the target slice. This also enables appropriate sidelink relaying through slice-specific relay reselection.

[0101] (Modification 1 of the first embodiment) In the first embodiment, a procedure for slice-specific relay reselection has been described. Slice-specific relay selection may also be performed by the above-described procedure for slice-specific relay reselection. In this case, when relay reselection is performed (step S18), a relay UE may be selected using a criterion specific to relay selection as the predetermined criterion.

[0102] (Modification 2 of the first embodiment) The second modification of the first embodiment is an example in which the relay UE 100-2 transmits additional information for each slice to the remote UE 100-1.

[0103] Specifically, first, a first relay user equipment (e.g., relay UE 100-2) transmits additional information for each network slice to a remote user equipment (e.g., remote UE 100-1). Second, the remote user equipment determines, based on the additional information, whether the QoS required by the remote user equipment is satisfied for each network slice, and performs a reselection process based on the determined network slice and the first slice support information.

[0104] This allows the remote UE 100-1 to reselect a relay UE that supports a slice that satisfies the QoS required by the remote UE 100-1 in the slice-specific relay station reselection. Therefore, it becomes possible to appropriately perform sidelink relaying in an assumed scenario.

[0105] (Example of operation of Modification 2) FIG. 10 is a diagram illustrating an example of operation according to a modification of the first embodiment.

[0106] As shown in Fig. 10, in step S30, the relay UE 100-2 transmits additional information to the remote UE 100-1. The additional information may be transmitted by being included in any one of a discovery message, a PC5-RRC message, and a PC5-S message. The additional information may be transmitted by being included in the slice support information of the first embodiment. Alternatively, the additional information may be transmitted by being included in the same message as the slice support information. Alternatively, the additional information may be transmitted by being included in a message separate from the slice support information.

[0107] The additional information may be the following. That is, the additional information may be information on a resource pool available for each slice and / or a resource pool unavailable (or not permitted) for each slice. Furthermore, the additional information may be information on a resource pool available for each slice and / or a resource pool unavailable (or not permitted) for each slice, and the information may be for each UE. Furthermore, the additional information may be the number of active PC5-connected UEs (remote UE 100-1) for each slice. Furthermore, the additional information may be a supportable throughput for each slice. Furthermore, the additional information may be a supportable delay for each slice.

[0108] In step S31, the remote UE 100-1 determines, for each slice, whether or not the QoS required by the remote UE 100-1 is satisfied, based on the additional information. If the remote UE 100-1 determines that the QoS required by the remote UE 100-1 for a certain slice is not satisfied, the remote UE 100-1 may determine that a relay UE supporting the slice does not satisfy the requirements of the intended slice. In this case, the remote UE 100-1 may exclude the relay UE from candidates for slice-specific relay station reselection. On the other hand, if the remote UE 100-1 determines that the QoS is satisfied for a certain slice, the remote UE 100-1 may determine that a relay UE supporting the slice satisfies the requirements of the desired slice, and may include the relay UE in the specific relay UEs (step S17 in FIG. 9).

[0109] In step S32, the remote UE 100-1 executes a slice-specific relay reselection process (steps S16 to S21 in FIG. 9) in consideration of the performance of each identified slice and the desired slice.

[0110] (Variation 3) The additional information may include "slice frequency information" of the serving cell 200-1. As described above, the slice frequency information includes a slice-specific frequency and one or more frequency priorities assigned to each frequency.

[0111] The relay UE 100-2 has received and acquired the slice frequency information of the serving cell 200-1 from the serving cell 200-1 in advance, and therefore, the relay UE 100-2 can transmit additional information including the slice frequency information to the remote UE 100-1 (step S30).

[0112] The remote UE 100-1 can select a specific relay UE by taking into consideration the slice frequency information in addition to the desired slice and slice support information (step S32). For example, consider a case where the desired slice is supported by two relay UEs, relay UE #1 and relay UE #2. Also, consider a case where the slice frequency information includes information indicating that relay UE #1 uses "800 MHz" for the desired slice and relay UE #2 uses "3.5 GHz" for the desired slice. In this case, the remote UE 100-1 can determine that it is better to connect to relay UE #1 from the perspective of the coverage of relay UE #1. Then, the remote UE 100-1 can perform a slice-specific relay reselection process (steps S16 to S21 in FIG. 9 ) with the relay UE #1 as the specific relay UE.

[0113] [Second embodiment] The second embodiment is an example in which the gNB 200-1 transmits information about the resource pool used in each slice to the relay UE 100-2.

[0114] 11 is a diagram showing an example of resource pool allocation. For example, assume that resource pool A is allocated exclusively to slice A, and resource pool B is allocated to slices B and C in a shared manner. In this case, since resource pool A is dedicated to slice A, more resources can be allocated to it than to slices B and C. Therefore, it is possible to prioritize access to slice A over access to slices B and C. Furthermore, since different resource pools are used for access to slice A and access to slices B and C, it is possible to suppress interference between the two accesses.

[0115] Specifically, first, a base station (e.g., gNB 200-1) transmits mapping information indicating a correspondence relationship between a network slice and a resource pool to a relay user equipment (e.g., relay UE 100-2). Second, the relay user equipment transmits the mapping information to a remote user equipment (e.g., remote UE 100-1). Third, the remote user equipment and the relay user equipment perform communication using the resource pool (e.g., communication by sidelink relay) based on the mapping information.

[0116] This allows, for example, the relay UE 100-2 and the remote UE 100-1 to perform side link relay using slice A with higher priority than side link relay using other slices based on the mapping information.

[0117] (Operation example according to the second embodiment) FIG. 12 is a diagram illustrating an example of operation according to the second embodiment.

[0118] In step S40, the gNB 200-1 transmits the resource pool information to the relay UE 100-2.

[0119] First, the resource pool information may be mapping information that indicates the correspondence between slices and resource pools. The mapping information may be information that specifies slices that can be used for each resource pool. In the example of FIG. 11, the mapping information specifies slice A for resource pool A, slice B for resource pool B, and slice C for resource pool B. The mapping information may also be information that specifies resource pools that can be used for each slice. In the example of FIG. 11, the mapping information specifies resource pool A for slice A, resource pool B for slice B, and resource pool B for slice C.

[0120] Second, the resource pool information may be mapping information indicating a correspondence relationship between the remote UE 100-1 and a resource pool. The mapping information may be information specifying a remote UE 100-1 that can be used for each resource pool. For example, in the example of FIG. 11, the mapping information is information specifying a resource pool A for the remote UE #1, and a resource pool B for the remote UE #2 and the remote UE #3. The mapping information may also be information specifying a resource pool that can be used for each remote UE 100-1. For example, in the example of FIG. 11, the mapping information is information specifying a resource pool A for the remote UE #1, a resource pool B for the remote UE #2, and a resource pool B for the remote UE #3.

[0121] In addition, the gNB 200-1 may transmit the resource pool information to the relay UE 100-2 by including the resource pool information in a message based on a predetermined layer and transmitting the message.

[0122] By transmitting the resource pool information, the gNB 200-1 can set a resource pool for each slice for the relay UE 100-2.

[0123] In step S41, the relay UE 100-2 transmits resource pool information to the remote UE 100-1. For example, the relay UE 100-2 may transmit the resource pool information by including it in any one of a PC5-RRC message, a PC5-S message, and a discovery message. The resource pool information is the same as the resource pool information in step S40. Note that the gNB 200-1 may transmit the resource pool information to the remote UE 100-1. In this case, the gNB 200-1 may transmit a Uu-RRC message or a Uu-PDCP message including the resource pool information to the remote UE 100-1. The relay UE 100-2 configures a resource pool for each slice for the remote UE 100-1 by transmitting the resource pool information to the remote UE 100-1.

[0124] In step S42, the relay UE 100-2 and the remote UE 100-1 perform side link relay using the resource pool based on the resource pool information.

[0125] [Third embodiment] Next, a third embodiment will be described.

[0126] In 3GPP, a slice-specific RACH is being discussed. The slice-specific RACH is a random access procedure performed using a random access opportunity (separated RO (RACH Occasion)) separated for each slice (or each slice group) and / or a preamble separated for each slice. The slice-specific RACH can prevent overlapping of resources between slices, slice groups, or between access using a slice and access not using a slice. Furthermore, by avoiding overlapping of resources, interference between RACHs transmitted by multiple UEs 100 can be reduced. Furthermore, it is also possible to prioritize access to a certain slice (or slice group) (by allocating resources that are less likely to cause interference).

[0127] For example, assume the following scenario: there is a remote UE 100-1 that wants to perform communication using an intended slice, and a relay UE 100-2 that supports the intended slice is in an RRC idle state or an RRC inactive state.

[0128] Therefore, in such a scenario, the remote UE 100-1 instructs the relay UE 100-2 to start a slice-specific RACH. As a result, the relay UE 100-2 is RRC connected to the gNB 200-1, and the remote UE 100-1 can perform communication using a desired slice via the relay UE 100-2.

[0129] Specifically, first, a remote user equipment (e.g., the remote UE 100-1) transmits a connection request message (e.g., a PC5-RRC connection request message) to a first relay user equipment (e.g., the relay UE 100-2) to establish a connection (e.g., a PC5-RRC connection) with the first relay user equipment. Second, the remote user equipment transmits a predetermined message to the relay user equipment to enable the first relay user equipment to establish a connection (e.g., a Uu-RRC connection) with a base station (e.g., the gNB 200-1). Third, the first relay user equipment performs a random access procedure with the base station using a RACH resource associated with a network slice identifier included in either the connection request message or the predetermined message.

[0130] (Operation example according to the third embodiment) FIG. 13 is a diagram illustrating an example of operation according to the third embodiment.

[0131] 13, the remote UE 100-1 is in the RRC idle state or the RRC inactive state (step S50). The relay UE 100-2 is also in the RRC idle state or the RRC inactive state (step S51). During the operation shown in FIG. 13, the remote UE 100-1 and the relay UE 100-2 maintain the RRC idle state or the RRC inactive state.

[0132] In step S52, the remote UE 100-1 decides to perform communication using a slice. For example, the NAS of the remote UE 100-1 notifies the AS of the remote UE 100-1 of a desired slice, and then notifies the AS of the remote UE 100-1 of a PC5-RRC connection request. Alternatively, the NAS of the remote UE 100-1 may notify the AS of the remote UE 100-1 of the desired slice together with the PC5-RRC connection request. The AS of the remote UE 100-1 may decide to perform communication using the desired slice based on the notification of the desired slice and the notification of the PC5-RRC connection request.

[0133] In step S53, the remote UE 100-1 transmits a PC5-RRC connection establishment request message to the relay UE 100-2. The PC5-RRC layer of the remote UE 100-1 may transmit the message to the PC5-RRC layer of the relay UE 100-2.

[0134] In step S54, a PC5-RRC connection is established on the PC5 link between the remote UE 100-1 and the relay UE 100-2.

[0135] In step S55, the remote UE 100-1 transmits a first message. The first message is a message transmitted from the remote UE 100-1 to the relay UE 100-2 to cause the relay UE 100-2 to establish an RRC connection with the gNB 200-1. In response to receiving the first message, the relay UE 100-2 starts establishing an RRC connection with the gNB 200-1. The first message may be transmitted as a PC5-RRC message. Note that, hereinafter, the first message may be referred to as a "predetermined message."

[0136] The predetermined message may be Msg3 (MSG3: third message), which is a message that is scheduled and transmitted first in the RACH procedure. Msg3 is an example of an RRC connection request message. The predetermined message may be an RRC setup request (RRCSetupRequest) message. Alternatively, the predetermined message may be an RRC connection resumption (RRCResumeRequest) message.

[0137] Here, the remote UE 100-1 includes the identifier of the slice (desired slice) determined in step S52 in either the PC5-RRC connection request message (step S53) or the predetermined message (step S55), and transmits the message.

[0138] In step S56, the relay UE 100-2 determines to start the RACH procedure in response to receiving the predetermined message. Then, in step S56, the relay UE 100-2 identifies a slice used by the remote UE 100-1 from a slice identifier included in the PC5-RRC connection request message or the predetermined message, and identifies a RACH resource associated with the slice. It is assumed that information on association between the slice and the RACH resource is included in a system information block (SIB) from the gNB 200-1 and has been received by the relay UE 100-2 from the gNB 200-1.

[0139] In steps S57 to S60, the relay UE 100-2 executes a slice-specific RACH procedure. That is, in step S57, the relay UE 100-2 transmits Msg1 (MSG1: first message) including a preamble on the PRACH to the gNB 200-1, using the RACH resource identified in step S56 (i.e., associated with the desired slice). In step S58, the gNB 200-1 transmits Msg2 (MSG2: second message) including resource allocation information and the like to the relay UE 100-2. In step S59, the relay UE 100-2 transmits Msg3 to the gNB 200-1, using the resource of the resource allocation information. When the relay UE 100-2 receives Msg3 in step S55, the relay UE 100-2 may transmit the Msg3. In step S60, the gNB 200-1 transmits Msg4 (MSG: fourth message) including control information related to the RRC connection to the relay UE 100-2.

[0140] (Modification of the third embodiment) Next, a modification of the third embodiment will be described.

[0141] The cell-specific RACH procedure (steps S57 to S60) described in the third embodiment may fail due to interference, etc. In this case, the relay UE 100-2 may not be able to establish an RRC connection with the gNB 200-1, and the remote UE 100-1 may not be able to communicate using a slice (desired slice) via the relay UE 100-2.

[0142] Therefore, in the modification of the third embodiment, an operation or process performed by the relay UE 100-2 when the RACH procedure fails will be described.

[0143] Specifically, first, when the first relay user equipment (e.g., the relay UE 100-2) fails in the random access procedure, it transmits a failure message including information indicating that the random access procedure has failed to the remote user equipment (e.g., the remote UE 100-1). Second, the remote user equipment performs a predetermined process in response to receiving the failure message. Here, the predetermined process is either the remote user equipment transmitting a request message including information indicating a request to the first relay user equipment to perform the random access procedure again, or the remote user equipment triggering reselection of the relay user equipment.

[0144] As a result, even if the cell-specific RACH procedure fails in the relay UE 100-2, the procedure is performed again or relay reselection is performed, so that the remote UE 100-1 can properly perform communication using slices.

[0145] (Example of operation of modified example) Fig. 14 is a diagram showing an example of operation according to a modification of the third embodiment. Note that, although Fig. 14 shows step S70 and subsequent steps, the explanation will be given assuming that steps S50 to S55 in the first embodiment (Fig. 13) have been performed before step S70.

[0146] In step S70, the relay UE 100-2 executes a slice-specific RACH procedure. In this procedure, the relay UE 100-2 transmits Msg1 by using the RACH resource associated with the slice (desired slice) used by the remote UE 100-1, as in the third embodiment (step S57 in FIG. 13).

[0147] In step S71, the relay UE 100-2 detects that the slice-specific RACH procedure has failed.

[0148] In step S72, the relay UE 100-2 sends a failure message including information indicating that the slice-specific RACH procedure has failed to the remote UE 100-1. The failure message may be sent as a PC5-RRC message.

[0149] In step S73, the remote UE 100-1 performs a predetermined process in response to receiving the failure message, which is either the remote UE 100-1 transmitting a request message including information indicating a request to the relay UE 100-2 to perform the cell-specific RACH procedure again, or the remote UE 100-1 triggering relay reselection.

[0150] When triggering relay station reselection, the remote UE 100-1 may select a slice (second network slice) with the next highest priority (e.g., second priority) after the slice (first network slice) with the highest priority (e.g., highest priority) used when selecting the relay UE 100-2. In this case, the remote UE 100-1 may select another relay UE that supports the slice. When triggering relay station reselection, the remote UE 100-1 may remove the current relay UE 100-2 from relay station reselection candidates and perform relay station reselection processing (e.g., FIG. 9).

[0151] [Other embodiments] A program may be provided that causes a computer to execute each process performed by the UE 100 (including the relay UE 100-2 and the remote UE 100-1) or the gNB 200. The program may be recorded on a computer-readable medium. Using the 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-transitory recording medium. The non-transitory recording medium is not particularly limited, and may be, for example, a recording medium such as a CD-ROM or a DVD-ROM.

[0152] In addition, circuits that execute each process performed by UE100 or gNB200 may be integrated, and at least a portion of UE100 or gNB200 may be configured as a semiconductor integrated circuit (chip set, SoC: System on a chip).

[0153] As used in this disclosure, the terms "based on" and "depending on" do not mean "based only on" or "depending only on," unless expressly stated otherwise. The term "based on" means both "based only on" and "based at least in part on." Similarly, the term "depending on" means both "based only on" and "at least in part on." Furthermore, "obtain" may mean obtaining information from stored information, obtaining information from information received from another node, or obtaining information by generating the information. The terms "include," "comprise," and variations thereof do not mean including only the listed items, but may also mean including only the listed items or including additional items in addition to the listed items. Furthermore, as used in this disclosure, the term "or" is not intended to mean an exclusive or. Furthermore, any reference to elements using designations such as "first," "second," etc., as used in this disclosure does not generally limit the quantity or order of those elements. These designations may be used herein as a convenient method of distinguishing between two or more elements. Thus, reference to first and second elements does not imply that only two elements may be employed therein or that the first element must precede the second element in some manner. In this disclosure, where articles are added by translation, such as a, an, and the in English, these articles shall include the plural unless the context clearly indicates otherwise.

[0154] The above describes one embodiment in detail with reference to the drawings, but the specific configuration is not limited to that described above, and various design changes can be made within the scope that does not deviate from the gist of the invention.

[0155] This application claims priority to U.S. Provisional Application No. 63 / 299,604 (filed January 14, 2022), the entire contents of which are incorporated herein by reference.

Claims

1. 1. A communication control method in a mobile communication system in which communication is performed between a remote user equipment and a base station via a first relay user equipment, comprising: The first relay user equipment transmits, to the remote user equipment, first slice support information including a network slice that the first relay user equipment can support, even without a request for a network slice from the remote user equipment; and and performing a reselection process by the remote user equipment to reselect a relay user equipment that supports a desired network slice that the remote user equipment desires to use based on the first slice support information. Communication control method.

2. The base station further includes transmitting QoS setting information indicating QoS for each of the network slices to the first relay user equipment. The communication control method according to claim 1.

3. The transmitting step includes transmitting, by the first relay user equipment, supportable slice information indicating the network slice that the first relay user equipment can support to the base station. The communication control method according to claim 1.

4. The transmitting step includes transmitting, from the first relay user equipment, second slice support information to the remote user equipment, the second slice support information indicating a network slice supported by a second relay user equipment adjacent to the first relay user equipment. The reselecting includes the remote user device performing the reselection process based on the first slice support information and the second slice support information. The communication control method according to claim 1.

5. and transmitting the second slice support information to the first relay user equipment.

5. The communication control method according to claim 4.

6. The transmitting step includes the first relay user equipment transmitting additional information for each network slice to the remote user equipment; The reselection includes the remote user device identifying, for each network slice, whether the network slice satisfies the QoS required by the remote user device based on the additional information, and performing the reselection process based on the identified network slice and the first slice support information. The communication control method according to claim 1.

7. The base station transmits mapping information indicating a correspondence between the network slice and a resource pool to the first relay user equipment; the first relay user equipment transmitting the mapping information to the remote user equipment; and performing the communication between the remote user equipment and the first relay user equipment using the resource pool based on the mapping information. The communication control method according to claim 1.

8. The method of claim 7, further comprising: transmitting, from the remote user equipment, a connection request message to the first relay user equipment to establish a connection to the first relay user equipment; the remote user equipment transmitting a predetermined message to the first relay user equipment to cause the first relay user equipment to establish a connection to the base station; The first relay user equipment performs a random access procedure with the base station using a RACH resource associated with an identifier of a network slice included in either the connection request message or the predetermined message. The communication control method according to claim 1.

9. and if the first relay user equipment fails the random access procedure, transmitting a failure message to the remote user equipment, the failure message including information indicating that the random access procedure has failed. the remote user device performs a predetermined process in response to receiving the failure message; The predetermined processing is the remote user equipment sending a request message to the first relay user equipment, the request message including information indicating a request to the first relay user equipment to perform the random access procedure again; and the remote user equipment triggering a reselection of a relay user equipment; Either The communication control method according to claim 8.

10. and triggering the reselection of the relay user equipment by the remote user equipment includes the remote user equipment reselecting a second relay user equipment supporting a second network slice having a next priority to a first network slice supported by the first relay user equipment. The communication control method according to claim 9.

11. the remote user equipment and the first relay user equipment are in an RRC idle state or an RRC inactive state; The communication control method according to claim 1 or 8.

12. A remote user equipment (REE) communicating with a base station via a relay user equipment (REE), comprising: a receiving unit that receives, from the relay user equipment, first slice support information including a network slice that the relay user equipment can support, without requesting a network slice from the relay user equipment; a control unit that performs a reselection process to reselect a relay user equipment that supports a desired network slice that the remote user equipment desires to use based on the first slice support information. Remote user device.

Images