Communication device, relay device, communication system, control method and program

Abstract

This technology provides a way to improve the immediacy between communication devices. [Solution] A communication device according to one aspect of the present disclosure includes receiving means for receiving a first message relating to relay communication from a relay device, and transmitting means for transmitting a second message relating to relay communication, wherein the first message includes information for identifying the communication device, and the second message includes the first message or information for identifying the relay device, the second message indicates that relay communication using the relay device is not performed in the communication performed by the communication device.

Description

Technical Field

[0001] The present disclosure relates to a communication device, a relay device, a communication system, a control method, and a program.

Background Art

[0002] In the 3rd Generation Partnership Project (3GPP (registered trademark): 3rd Generation Partnership Project), cellular communication standards (also referred to as 3GPP standards) have been formulated. In recent years, the formulation of the specifications for 3GPP's LTE (Long Term Evolution) and NR (New Radio) has been progressing. Among these, a standard specification called Sidelink communication (hereinafter referred to as Sidelink) has been formulated. This specification realizes direct wireless communication between devices using an interface called PC5 without going through a mobile communication network (core network).

[0003] In 3GPP, the formulation of a specification for expanding the communication range of Sidelink by a Sidelink relay function that relays Sidelink communication via a relay device (relay UE: Relay User Equipment) is underway. Note that UE may be referred to as a terminal device or simply a terminal.

[0004] In Patent Document 1, a method is proposed in which a remote UE broadcasts a request including a relay indication indicating the number of relays, and establishes a communication link between remote UEs via a relay UE.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] After searching for a relay UE and deciding to communicate through that relay UE, the remote UE or relay UE may move, bringing the remote UE and other remote UEs that the remote UE has requested a connection to within direct communication range. However, the method for establishing a direct communication connection in this case is not clearly defined. Therefore, direct communication between remote UEs may not be possible, potentially leading to a situation with low immediacy between remote UEs.

[0007] One aspect of this disclosure, in view of the above, aims to provide a technology that improves the immediacy between communication devices. [Means for solving the problem]

[0008] A communication device according to one aspect of the present disclosure includes receiving means for receiving a first message relating to relay communication from a relay device, and transmitting means for transmitting a second message relating to relay communication, wherein the first message includes information for identifying the communication device, and the second message includes the first message or information for identifying the relay device, the second message indicates that relay communication using the relay device is not performed in the communication performed by the communication device. [Effects of the Invention]

[0009] According to one aspect of this disclosure, the immediacy between communication devices can be improved. [Brief explanation of the drawing]

[0010] [Figure 1] This figure shows an example of the positional relationship of the communication device according to the first embodiment. [Figure 2] This is a block diagram showing an example of the functional configuration of a remote UE according to the first embodiment. [Figure 3] This is a block diagram showing an example of the functional configuration of a relay UE according to the first embodiment. [Figure 4] This is a sequence diagram showing an example of operation of a communication device according to the first embodiment. [Figure 5] This flowchart shows an example of the operation of the communication device according to the first embodiment. [Figure 6] This diagram shows an example of the configuration for Relay Indication. [Figure 7] This figure shows an example of the positional relationship of the communication devices according to the second embodiment. [Figure 8] This is a sequence diagram showing an example of operation of a communication device according to the second embodiment. [Figure 9] This is a flowchart showing an example of the operation of the communication device according to the second embodiment. [Figure 10] This figure shows an example of the positional relationship of the communication devices according to the third embodiment. [Figure 11] This is a block diagram showing an example of the functional configuration of a base station according to the third embodiment. [Figure 12] This is a sequence diagram showing an example of operation of a communication device according to the third embodiment. [Figure 13] This flowchart shows an example of the operation of a communication device according to the third embodiment. [Modes for carrying out the invention]

[0011] The embodiments will be described in detail below with reference to the attached drawings. Note that the following embodiments do not limit the scope of the claims. While the embodiments describe multiple features, not all of these features are essential to the invention, and the features may be combined in any way. Furthermore, in the attached drawings, the same or similar configurations are given the same reference numeral, and redundant descriptions may be omitted.

[0012] <First Embodiment> [System Configuration] Figure 1 shows an example of the positional relationship of the communication devices according to the first embodiment. In various embodiments, including this embodiment, the wireless communication system may be a next-generation mobile communication system such as NR (5G), 6G, LTE, LTE-A (LTE-Advanced), or a combination thereof.

[0013] In wireless communication systems such as those shown in FIG. 1 and the like in various embodiments including the present embodiment, proximity-based services (ProSe) that enable UEs to communicate directly with each other are provided. ProSe may also be referred to as D2D (Device-to-Device) services. This makes it possible, for example, to improve frequency utilization efficiency and overall throughput, and to reduce the power consumption of UEs. The UEs described below support ProSe and may also be referred to as ProSe UEs or ProSe-capable UEs.

[0014] In FIG. 1, the wireless communication system includes a remote UE 101, a remote UE 102, and a relay UE 103. In the present embodiment, it is assumed that the remote UE 101 requests a communication connection with the remote UE 102 as a communication partner. Therefore, the remote UE 101 is called the source UE, and the remote UE 102 is called the target UE. In FIG. 1, the remote UE 101 is described as Source UE-1, the remote UE 102 is described as Target UE-2, and the relay UE 103 is described as Relay UE-3. The relay UE 103 is an example of an inter-terminal relay device.

[0015] FIG. 1(a) shows an example of the positional relationship of communication devices before network construction determination, and FIG. 1(b) shows an example of the positional relationship of communication devices after network construction determination. Here, network construction determination refers to path determination after confirming the location of neighboring UEs through discovery.

[0016] FIG. 1(a) shows that before network construction determination, the remote UE 101 and the remote UE 102 communicate via the relay UE 103. On the other hand, FIG. 1(b) shows that after network construction determination, the remote UE 101 and the remote UE 102 communicate directly with each other.

[0017] [Configuration of the device] Next, the functional configuration of the communication device according to this embodiment will be described. Note that the configuration of the functional blocks described below is merely an example.

[0018] Furthermore, some (and sometimes all) of the functional blocks described below may be replaced with other functional blocks that perform similar functions, some functional blocks may be omitted, and additional functional blocks may be added.

[0019] Furthermore, one functional block described below may be divided into multiple functional blocks, or multiple functional blocks may be integrated into one functional block.

[0020] Figure 2 is a block diagram showing an example of the functional configuration of remote UEs (remote UE101, remote UE102) according to the first embodiment.

[0021] As shown in Figure 2, each of the remote UEs 101 and 102 has a control unit 201, a storage unit 202, a message generation processing unit 203, a message analysis processing unit 204, and a wireless communication unit 205.

[0022] The control unit 201 is composed of, for example, a processor such as a CPU or MPU, an application-specific integrated circuit (ASIC), a digital signal processor (DSP), a field-programmable gate array (FPGA), etc. CPU is an abbreviation for Central Processing Unit, and MPU is an abbreviation for Micro Processing Unit. The control unit 201 controls the entire remote UE 101 and 102, for example, by executing a program stored in the memory unit 202. Alternatively, the control unit 201 may control the remote UE 101 and 102 in cooperation with the program stored in the memory unit 202 and the operating system (OS). The control unit 201 is an example of a decision means.

[0023] The storage unit 202 is configured to include, for example, memory such as ROM (Read Only Memory) and RAM (Random Access Memory). The storage unit 202 stores various information such as programs for performing various operations described later, communication parameters for wireless communication, and data processed or processed by the remote UEs 101 and 102. In addition to memory such as ROM and RAM, the storage unit 202 may also be configured to include storage media such as flexible disks, hard disks, optical disks, magneto-optical disks, CD-ROMs, CD-Rs, magnetic tapes, non-volatile memory cards, and DVDs. CD is an abbreviation for Compact Disc, CD-R is an abbreviation for Compact Disc Recordable, and DVD is an abbreviation for Digital Versatile Disc.

[0024] The message generation processing unit 203 is composed of a general-purpose processor such as a CPU (for example, implemented as a program), a dedicated processing circuit, etc. The message generation processing unit 203 generates signals and messages to be transmitted to neighboring UEs, including neighboring relay UEs (for example, relay UE 103). Such signals and messages include discovery signals, response signals to discovery signals, Request Messages, Response Messages, Cancel Request Messages, etc. Request Messages, Response Messages, and Cancel Request Messages will be described later. The message generation processing unit 203 is an example of a generation means.

[0025] The message analysis processing unit 204 is composed of a general-purpose processor such as a CPU (for example, implemented as a program), dedicated processing circuits, etc. The message analysis processing unit 204 analyzes signals and messages transmitted from neighboring UEs, including neighboring relay UEs (for example, relay UE 103). Such signals and messages include discovery signals, response signals to discovery signals, request messages, response messages, cancel request messages, etc.

[0026] The wireless communication unit 205 includes hardware (e.g., a radio frequency (RF) chip, a baseband chip, etc.) for performing wireless communication compliant with the 3GPP cellular communication standard. The wireless communication unit 205 may be composed of a general-purpose processor such as a CPU (for example, implemented as a program). The wireless communication unit 205 controls one or more corresponding antennas to transmit and receive wireless signals. The wireless communication unit 205 communicates information wirelessly with neighboring UEs, including nearby relay UEs, and base stations (not shown). The wireless communication unit 205 performs the transmission process of messages generated by the message generation processing unit 203, and the reception process of messages transmitted from neighboring UEs, including nearby relay UEs, and base stations. The wireless communication unit 205 is an example of a transmitting means, a receiving means, or a communication means.

[0027] Figure 3 is a block diagram showing an example of the functional configuration of a relay UE (relay UE103) according to the first embodiment.

[0028] As shown in Figure 3, the relay UE103 includes a control unit 301, a storage unit 302, a message generation processing unit 303, a message analysis processing unit 304, a wireless communication unit 305, and a Sidelink Relay processing unit 306.

[0029] The control unit 301 is composed of, for example, a processor such as a CPU or MPU, an ASIC, a DSP, or an FPGA. The control unit 301 controls the entire relay UE 103 by, for example, executing a program stored in the memory unit 302. Alternatively, the control unit 301 may control the relay UE 103 in cooperation with the program stored in the memory unit 302 and the OS.

[0030] The storage unit 302 is configured to include, for example, memory such as ROM or RAM. The storage unit 302 stores various information such as programs for performing various operations described later, communication parameters for wireless communication, and data processed or processed by the relay UE 103. In addition to memory such as ROM or RAM, the storage unit 302 may also be configured to include storage media such as flexible disks, hard disks, optical disks, magneto-optical disks, CD-ROMs, CD-Rs, magnetic tapes, non-volatile memory cards, and DVDs.

[0031] The message generation processing unit 303 is composed of a general-purpose processor such as a CPU (for example, implemented as a program), a dedicated processing circuit, etc. The message generation processing unit 303 generates signals and messages to be transmitted to neighboring UEs, including neighboring relay UEs. Such signals and messages include discovery signals, response signals to discovery signals, request messages, response messages, etc. The message generation processing unit 303 is an example of a generation means.

[0032] The message analysis processing unit 304 is comprised of a general-purpose processor such as a CPU (for example, implemented as a program), dedicated processing circuits, etc. The message analysis processing unit 304 analyzes signals and messages transmitted from neighboring UEs, including neighboring relay UEs. Such signals and messages include discovery signals, response signals to discovery signals, request messages, response messages, cancel request messages, etc.

[0033] The wireless communication unit 305 includes hardware (e.g., an RF chip, a baseband chip, etc.) for performing wireless communication compliant with the 3GPP cellular communication standard. The wireless communication unit 305 may be composed of a general-purpose processor such as a CPU (for example, implemented as a program). The wireless communication unit 305 controls one or more corresponding antennas to transmit and receive wireless signals. The wireless communication unit 305 communicates information wirelessly with neighboring UEs, including nearby relay UEs, and base stations (not shown). The wireless communication unit 305 performs the transmission process of messages generated by the message generation processing unit 303, and the reception process of messages transmitted from neighboring UEs, including nearby relay UEs, and base stations. The wireless communication unit 305 is an example of a transmitting means, a receiving means, or a communication means.

[0034] The Sidelink Relay processing unit 306 establishes a Sidelink connection with remote UEs (e.g., remote UEs 101 and 102) and enables relay connections between the Sidelink-connected remote UEs and a base station or other remote UEs.

[0035] [Processing of the device] Next, referring again to Figure 1, the processing of the communication device according to this embodiment will be explained using Figures 4 and 5. Figure 4 is a sequence diagram showing an example of operation of the communication device according to the first embodiment. Figure 5 is a flowchart showing an example of operation of the communication device according to the first embodiment.

[0036] Source UE101 performs discovery when it wants to communicate with target UE102. Initially, source UE101, target UE102, and relay UE103 are in the positional relationship shown in Figure 1(a). Source UE101 searches for target UE102, but since it cannot find target UE102 within its communication range, it searches for a nearby relay (repeater, relay UE). As a result of the relay search, source UE101 finds relay UE103. Then, relay UE103 searches for target UE102 and finds target UE102 within its communication range. Therefore, source UE101 decides to communicate with target UE102 via relay UE103.

[0037] Subsequently, as the source UE101 and target UE102 move closer together, and the relay UE103 moves further away from the source UE101 and target UE102, the position and communication range of the source UE101, target UE102, and relay UE103 change. This change is shown, for example, in Figure 1(b).

[0038] Source UE101 broadcasts a Request Message (F401) to communicate via the relay UE. The Request Message is a connection request (in other words, a request for communication with target UE102 involving relay communication) from source UE101 to target UE102 (via the relay UE). The Request Message contains the identifier (ID) of target UE102, which is information to identify target UE102 (for example, in the Target ID field). The Request Message also contains information or an indicator (Relay Indication) that shows whether the relay connection or relay communication is enabled or disabled.

[0039] The Relay Indication Information Element (IE) shown in Figure 6 is described in Section 11.3.56 of 3GPP Technical Specification (TS) 24.554. Details of the information within this information element are shown in the table below. [Table 1]

[0040] According to Table 1, the Relay Indication (parameter) described in TS24.554 is 1 bit. The Relay Indication in this embodiment may also be 1 bit. In this embodiment, a Relay Indication of "1 (True)" indicates that the relay connection is enabled, and a Relay Indication of "0 (False)" indicates that the relay connection is disabled. In other embodiments, "1" and "0" may have opposite meanings. In this embodiment, the source UE 101 broadcasts a Request Message with the Relay Indication set to "1". The relay UE sets the Relay Indication to "0" if it is the last relay UE (i.e., the next connection is the target UE), and sets the Relay Indication to "1" otherwise. The relay UE then broadcasts or unicasts a Request Message with the Relay Indication set in this way. In other words, the Relay Indication included in the Request Message sent by the relay UE can be said to be information indicating that relay communication using the relay UE is possible. Hereafter, a Relay Indication indicating that a relay connection is active will be referred to as an active Relay Indication, and a Relay Indication indicating that a relay connection is inactive will be referred to as an inactive Relay Indication.

[0041] Alternatively, the Relay Indication according to this embodiment may be a natural number, unlike the Relay Indication described in TS24.554. In that case, the Relay Indication may indicate an upper limit on the number of relay hops. For example, Relay Indication=2 (initial value) means that the upper limit on the number of relay UEs that relay between source UE101 and target UE102 is 2. When Relay Indication is a natural number, each time a relay UE is hopped (relayed), the relay UE decrements Relay Indication by 1. When Relay Indication becomes 0 after hopping through a relay UE, the relay UE does not send a Request Message. "Does not send a Request Message" may be rephrased as "drops the Request Message". Alternatively, if Relay Indication becomes 0, the implementation may set Relay Indication to empty (null) to indicate that the relay connection is invalid. In this case, the relay UE may send a Request Message. A natural number for Relay Indication may be interpreted as indicating that the relay connection is valid. In other words, the natural number Relay Indication included in the Request Message transmitted by the relay UE can be considered information indicating that relay communication using the relay UE is possible. The initial value of the Relay Indication (i.e., the value included in the Request Message transmitted by the source UE 101) may be fixed by the specification. Alternatively, the initial value of the Relay Indication may be arbitrarily selected by the source UE 101 from a predetermined set of candidate values. Furthermore, the initial value of the Relay Indication may be set by the base station. Alternatively, the initial value of the Relay Indication may be selected by the source UE 101 from a set of candidate values ​​set by the base station.

[0042] Here, the initial value of Relay Indication is set to 1, and if Relay Indication becomes 0, a Request Message is sent indicating that the relay connection is disabled.

[0043] Furthermore, the Request Message in F401 may include information for identifying the Request Message, such as a Message identifier, session number, or message number. In the example shown in Figure 4, the Request Message in F401 is received by the relay UE103 and the target UE102.

[0044] Relay UE103 waits for a Request Message with a valid Relay Indication (S505). Upon receiving a Request Message in F401 (with a valid Relay Indication), Relay UE103 transmits the Request Message by broadcast or unicast (F402, S506). The Request Message in F402 is an example of a message related to relay communication. The Request Message in F402 may also be called a message regarding the implementation of relay communication, a message regarding the feasibility of relay communication, a message indicating that relay communication is possible, etc. Relay UE103 may transmit the Request Message in F402 multiple times (for example, repeatedly at regular intervals). In this case, Relay UE103 issues a timer after transmitting the first Request Message, and terminates the transmission of Request Messages when the timer expires. Also, when Relay UE103 receives a Cancel Request Message in F404 from Target UE102, as described below, it terminates the transmission of Request Messages (Yes in S507). A Cancel Request Message can also be described as a message used to cancel communication via a relay UE, and therefore could also be called a Cancel Relay Message.

[0045] The Request Message in F402 is received by the target UE102. If the Request Message in F402 is sent via broadcast, it may also be received by the source UE101. However, since source UE101 has already sent the original Request Message, it will ignore the Request Message it receives in F402.

[0046] The Request Message in F402 also includes the ID of the target UE102 (for example, in the Target ID field). The Request Message in F402 further includes the Request Message number or the ID of the relay UE103.

[0047] Target UE102 determines whether it has received a Request Message two or more times (S501). If Target UE102 has not received a Request Message two or more times, it waits (No in S501). In the example shown in Figure 4, Target UE102 has received a Request Message in F401 and F402, so it proceeds to S502 (Yes in S501). Regarding the number of times a Request Message is received (two or more times), the second and subsequent receptions of a Request Message sent from the same communication device (relay UE103) may or may not be counted.

[0048] Target UE102 determines whether the Request Message contains one or more valid Relay Indications and two or more instances of the ID of Target UE102 (S502).

[0049] In S501 and S502, the target UE102 determines whether it has received connection requests from two or more paths, and whether at least one of those paths is via relay. For example, consider a case where the target UE102 receives two Request Messages, each containing one valid Relay Indication and both containing the target UE102 ID. In this case, the target UE102 recognizes that there are connection requests (Request Messages) from two paths, one of which is via relay, and the other is not via relay.

[0050] If target UE102 receives a Request Message two or more times, and the Request Message contains a valid Relay Indication and the ID of target UE102, it determines as follows: Target UE102 determines that the connection request is not routed via the relay (i.e., directly from source UE101). Also, if target UE102 receives a Request Message that contains the ID of target UE102 but does not contain a valid Relay Indication, it determines as follows: Target UE102 determines that the connection request is routed via the relay (i.e., via relay UE103).

[0051] In S502, if the Request Message does not contain a valid Relay Indication at least once, or if the ID of target UE102 is not included at least twice, target UE102 will wait (No in S502).

[0052] If the Request Message contains one or more valid Relay Indications and the ID of Target UE102 is included two or more times (Yes in S502), Target UE102 operates as follows: Based on the Request Messages in F401 and F402, Target UE102 decides whether or not to send a Cancel Request Message (F403, S503). In the example shown in Figure 4, for example, Target UE102 compares the received power (or received quality) of the Request Message in F401 with the received power (or received quality) of the Request Message in F402. If the received power of the Request Message in F401 is greater than the received power of the Request Message in F402, Target UE102 decides to send a Cancel Request Message. On the other hand, if the received power of the Request Message in F401 is less than or equal to the received power of the Request Message in F402, Target UE102 decides not to send a Cancel Request Message. Alternatively, if the difference in received power of these Request Messages is within a predetermined value (e.g., 10 dB), the target UE102 may decide to send a Cancel Request Message. On the other hand, if the difference in received power of these Request Messages is not within a predetermined value, the target UE102 may decide not to send a Cancel Request Message.

[0053] Thus, if the Request Message in F402 includes the ID of the target UE102, the target UE102 decides to send a Cancel Request Message based on the received power or received quality of this message. In other words, in this case, the target UE102 decides, based on the received power or received quality, that relay communication using the relay UE103 that sent this message will not be performed in the communication conducted by the target UE102. This decision is made, for example, by the control unit 201.

[0054] If it decides to send a Cancel Request Message (Yes in S503), Target UE102 sends the Cancel Request Message by broadcast or unicast (F404, S504). The Cancel Request Message in F404 is an example of a message related to relay communication. The Cancel Request Message may also be called a message regarding the execution of relay communication, a message regarding the feasibility of relay communication, or a message indicating that relay communication will not be performed. The Cancel Request Message contains the number of the Request Message in F402 that is to be canceled, or the ID of the relay UE103 that sent the Request Message in F402 that is to be canceled. If the Cancel Request Message in F404 is sent by broadcast, it may also be received by Source UE101. However, since Source UE101 sent the original Request Message and did not send the Request Message to be canceled, it will ignore the Cancel Request Message in F404 even if it receives it.

[0055] Upon receiving the Cancel Request Message in F404, Relay UE103 terminates the transmission of the Request Message in F402 as described above, and ends this process (Yes in S507).

[0056] If it decides not to send a Cancel Request Message (No in S503), Target UE102 terminates this process. Then, Target UE102 performs the normal process of connecting to Relay UE103 (not shown).

[0057] After sending the Cancel Request Message in F404, Target UE102 sends a response message to Source UE101 in response to the Request Message in F401 (S501) (F405, S508). The response message in F405 indicates that the communication performed by Target UE102 is with Source UE101.

[0058] Upon receiving the Response Message in F405, source UE101 connects directly to target UE102 and communicates directly with target UE102 via unicast (F406).

[0059] Thus, a Cancel Request Message can be described as a message, information, or signal indicating that relay communication using the relay UE (relay UE103 in this embodiment) that sent the Request Message will not be performed.

[0060] In this embodiment, the Request Message includes the ID of the target UE, and the Cancel Request Message includes information for identifying the Request Message or the relay UE that sent the Request Message. In this case, the Cancel Request Message indicates that relay communication using the relay UE that sent the Request Message will not be performed in the communication conducted by the target UE.

[0061] As explained above, by target UE102 sending a request message cancellation, source UE101 and target UE102 can communicate directly without going through relay UE103. As a result, the immediacy between source UE101 and target UE102 is improved. Furthermore, the connection waiting time of relay UE103 is reduced, and the connection between relay UE103 and target UE102 becomes unnecessary, thereby reducing the time and frequency resources between relay UE103 and target UE102.

[0062] <Second Embodiment> In the first embodiment, an example was described in which one relay UE is interposed between the source UE and the target UE. In the second embodiment, an example is described in which two relay UEs are interposed between the source UE and the target UE.

[0063] [System Configuration] Figure 7 shows an example of the positional relationship of the communication devices according to the second embodiment.

[0064] In Figure 7, the wireless communication system includes Remote UE701, Remote UE702, Relay UE703, and Relay UE704. In this embodiment, Remote UE701 requests a communication connection from Remote UE702 as its communication partner. Therefore, Remote UE701 is called the Source UE, and Remote UE702 is called the Target UE. In Figure 7, Remote UE701 is labeled Source UE-1, Remote UE702 is labeled Target UE-2, Relay UE703 is labeled Relay UE-3, and Relay UE704 is labeled Relay UE-4. Relays UE703 and 704 are examples of inter-terminal relay devices and are connected in a multi-stage configuration.

[0065] Figure 7(a) shows an example of the positional relationship of communication devices before the network configuration decision, and Figure 7(b) shows an example of the positional relationship of communication devices after the network configuration decision. Here, the network configuration decision refers to the route determination after confirming the location of neighboring UEs through discovery.

[0066] Figure 7(a) shows that before the network configuration is decided, remote UE701 and remote UE702 communicate via relay UE703 and 704. On the other hand, Figure 7(b) shows that after the network configuration is decided, remote UE101 and remote UE102 communicate only via relay UE703.

[0067] [Device Configuration] The functional configurations of remote UE701 and 702 are the same as those of remote UE101 and 102 in the first embodiment, so their description is omitted. Similarly, the functional configurations of relay UE703 and 704 are the same as those of relay UE103 in the first embodiment, so their description is omitted.

[0068] [Processing of the device] Next, referring again to Figure 7, the processing of the communication device according to this embodiment will be explained using Figures 8 and 9. Figure 8 is a sequence diagram showing an example of operation of the communication device according to the second embodiment. Figure 9 is a flowchart showing an example of operation of the communication device according to the second embodiment.

[0069] Source UE701 performs discovery when it wants to communicate with target UE702. Initially, source UE701, target UE702, relay UE703, and relay UE704 are in the positional relationship shown in Figure 7(a), for example. Source UE701 searches for target UE702, but since it cannot find target UE702 within its communication range, it searches for nearby relays. As a result of the relay search, source UE101 finds relay UE703. Relay UE703 searches for target UE702, but since it cannot find target UE702 within its communication range, it finds relay UE704. Then, relay UE704 searches for target UE702 and finds target UE702 within its communication range. Therefore, source UE701 decides to communicate with target UE702 via relays UE703 and 704.

[0070] Subsequently, the source UE701 and target UE702 move closer together, and relay UE704 moves further away from source UE701 and target UE702, causing changes in the positions and communication range of UE701-704. This change is illustrated, for example, in Figure 7(b).

[0071] Source UE701 broadcasts a Request Message (F801) to communicate via the relay UE. The Request Message in F801 is the same as the Request Message in F401 according to the first embodiment, so its explanation is omitted. In the example shown in Figure 8, the Request Message in F801 is received by relay UE703.

[0072] Relay UE 703 waits for a Request Message with a valid Relay Indication (S905). Upon receiving a Request Message in F801 (with a valid Relay Indication), Relay UE 703 broadcasts the Request Message (F802, S906). The Request Message in F802 is an example of a message related to relay communication. The Request Message in F802 may also be called a message regarding the implementation of relay communication, a message regarding the feasibility of relay communication, a message indicating that relay communication is possible, etc. In the example shown in Figure 8, the Request Message in F802 is received by Relay UE 704 and Target UE 702. The Request Message in F802 may also be received by Source UE 701. However, since Source UE 701 has already sent the original Request Message, it ignores the Request Message in F802. The Request Message in F802 is the same as the Request Message in F401 or F402 according to the first embodiment, so its explanation is omitted.

[0073] Relay UE704 transmits a Request Message by broadcast or unicast (F803). The Request Message in F803 is an example of a message related to relay communication. The Request Message in F803 may also be called a message regarding the implementation of relay communication, a message regarding the feasibility of relay communication, a message indicating that relay communication is possible, etc. Since the Request Message in F803 is the same as the Request Message in F401 or F402 in the first embodiment, its explanation is omitted. In the example shown in Figure 8, the Request Message in F803 is received by target UE702.

[0074] Similar to the first embodiment, target UE102 determines whether it has received two or more Request Messages (S901), and if it has not received two or more Request Messages, it waits (No in S901). In the example shown in Figure 9, target UE702 has received Request Messages from relay UE703 and 704, so it proceeds to S902 (YES in S901). Regarding the number of Request Messages received (two or more), the second and subsequent receptions of Request Messages sent from the same communication device (relay UE703 or 704) may or may not be counted.

[0075] Target UE702 determines whether the Request Message contains one or more valid Relay Indications and whether the ID of Target UE702 is included two or more times (S902). In the example shown in Figure 9, the Request Message contains one or more valid Relay Indications and the ID of Target UE702 is included two or more times, so Target UE702 proceeds to S903.

[0076] Target UE702 determines whether or not to send a Cancel Request Message based on the Request Messages in F802 and F803 (F804, S903).

[0077] If it is determined to send a Cancel Request Message (Yes in S903), the target UE702 sends the Cancel Request Message by broadcast or unicast (F805, S904). The Cancel Request Message in F805 is an example of a message related to relay communication. The Cancel Request Message may also be referred to as a message regarding the execution of relay communication, a message regarding the feasibility of relay communication, or a message indicating that relay communication will not be performed. The Cancel Request Message includes the number of the Request Message in F803 that is to be canceled, or the ID of the relay UE704 that sent the Request Message in F803 that is to be canceled.

[0078] Here, the target (destination) of the Cancel Request Message is, for example, the relay UE that sent the Request Message that does not have the lowest number among the Request Messages. This is because it connects to the relay UE that sent the Request Message with the lowest number and cancels all Request Messages other than the lowest number.

[0079] Alternatively, if the Relay Indication included in the Request Message is a natural number, the target (destination) of the Cancel Request Message may be, for example, as follows: The target (destination) of the Cancel Request Message may be the relay UE that sent the Request Message whose Relay Indication is not the largest. This is to connect to the relay UE that sent the Request Message whose Relay Indication is the largest and cancel all Request Messages other than the largest Relay Indication.

[0080] Alternatively, Target UE 702 may send a Cancel Request Message to relay UEs that have sent a predetermined number of Request Messages, starting with those with the lowest received power or received quality. Target UE 702 may decide, based on the received power of the Request Messages, that relay communication using the relay UEs that sent the Request Messages will not be performed in the communication conducted by Target UE 702. Target UE 702 may also decide, based on the received quality of the Request Messages, that relay communication using the relay UEs that sent the Request Messages will not be performed in the communication conducted by Target UE 702. This decision may be made, for example, by a control unit similar to the control unit 201.

[0081] In the example shown in Figure 9, target UE702 sends a Cancel Request Message to relay UE704, which sent the Request Message in F803. However, target UE702 may also send separate Cancel Request Messages to each of the one or more relay UEs that each sent one or more other Request Messages. Alternatively, target UE702 may include the numbers of the multiple Request Messages to be canceled, or the IDs of the multiple relay UEs that each sent these multiple messages, in a single Cancel Request Message. Target UE702 may then send the Cancel Request Message via broadcast or multicast.

[0082] Upon receiving the Cancel Request Message in F805, Relay UE704 terminates the transmission of the Request Message in F803 as described above, and ends this process (Yes in S907).

[0083] If it decides not to send a Cancel Request Message (No in S903), target UE702 terminates this process. Then, target UE702 performs the normal process of connecting to relay UE704 (not shown).

[0084] After sending the Cancel Request Message in F805, Target UE702 sends a response message to the Request Message in F802(S901) back to Relay UE703 (F806, S908). The response message in F806 indicates that relay communication using Relay UE703 will be performed in the communication conducted by Target UE702.

[0085] Upon receiving the Response Message in F806, relay UE703 forwards the Response Message to source UE701 (F807). The Response Message in F807 indicates that the communication conducted by target UE702 is with source UE701.

[0086] Upon receiving the Response Message in F807, source UE701 connects to target UE702 via relay UE703 and communicates with target UE702 via unicast (F808).

[0087] Furthermore, when source UE701 communicates with target UE702 via unicast, the provisions of the current 3GPP standard may be applied. For example, the provisions of sections 6.7.3.2 and 6.7.3.3 of TS23.304 may be applied before the processing shown in F808. Specifically, one or more of the following processes may be executed before the processing shown in F808. • Establish security between relay UE703 and target UE702 (if necessary). • Assigning an IP (Internet Protocol) v6 prefix or IPv4 address to the target UE702 (for IP traffic). • Establish security between source UE701 and relay UE703 (if necessary). • Assigning an IPv6 prefix or IPv4 address to source UE701 (for IP traffic). • DNS (Domain Name System) query / response (in the case of IP communication).

[0088] Thus, a Cancel Request Message can be described as a message, information, or signal indicating that relay communication using the relay UE (relay UE704 in this embodiment) that sent the Request Message will not be performed.

[0089] In this embodiment, the Request Message includes the ID of the target UE, and the Cancel Request Message includes information for identifying the Request Message or the relay UE that sent the Request Message. In this case, the Cancel Request Message indicates that relay communication using the relay UE that sent the Request Message will not be performed in the communication conducted by the target UE.

[0090] As explained above, by having the target UE702 send a request message cancellation, communication becomes possible with fewer relay UEs intervening between the source UE701 and the target UE702. As a result, the immediacy between the source UE701 and the target UE702 is improved. Furthermore, the connection waiting time of relay UE704 is reduced, and the connection between relay UE704 and the target UE702 becomes unnecessary, thereby reducing the time and frequency resources between relay UE704 and the target UE702.

[0091] Although this embodiment describes an example where there are two relay UEs, this embodiment can also be applied when there are three or more relay UEs.

[0092] <Third Embodiment> The first and second embodiments described examples where one or two relay UEs are interposed between the source UE and the target UE. The third embodiment describes an example where one relay UE is interposed between the base station equipment and the target UE. The base station equipment may simply be referred to as a base station or gNB (gNodeB).

[0093] [System Configuration] Figure 10 shows an example of the positional relationship of the communication device according to the third embodiment.

[0094] In Figure 10, the wireless communication system includes a base station 1001, a remote UE 1002, and a relay UE 1003. In this embodiment, the base station 1001 requests a communication connection from the remote UE 1002 as its communication partner. Therefore, the remote UE 1002 is referred to as the target UE. In Figure 10, the base station 1001 is labeled as gNB, the remote UE 1002 is labeled as Target UE-1, and the relay UE 1003 is labeled as Relay UE-2. The relay UE 1003 is an example of a base station-terminal relay device.

[0095] Figure 10(a) shows an example of the positional relationship of communication devices before the network configuration decision, and Figure 7(b) shows an example of the positional relationship of communication devices after the network configuration decision. Here, the network configuration decision refers to the route determination after confirming the location of neighboring UEs through discovery.

[0096] Figure 10(a) shows that before the network configuration is decided, the base station 1001 and the remote UE 1002 communicate via the relay UE 1003. On the other hand, Figure 10(b) shows that after the network configuration is decided, the base station 1001 and the remote UE 102 communicate directly with each other.

[0097] [Device Configuration] The functional configuration of the remote UE1002 is the same as that of the remote UE101 and 102 in the first embodiment, so its description is omitted. Similarly, the functional configuration of the relay UE1003 is the same as that of the relay UE103 in the first embodiment, so its description is omitted.

[0098] Figure 11 is a block diagram showing an example of the functional configuration of a base station (base station 1001) according to the third embodiment.

[0099] As shown in Figure 11, the base station 1001 includes a control unit 1101, a storage unit 1102, a message generation processing unit 1103, a message analysis processing unit 1104, a wireless communication unit 1105, and a communication unit 1106.

[0100] The control unit 1101 is composed of, for example, a processor such as a CPU or MPU, an ASIC, a DSP, or an FPGA. The control unit 1101 controls the entire base station 1001 by, for example, executing a program stored in the memory unit 1102. Alternatively, the control unit 1101 may control the base station 1001 in cooperation with the OS and a program stored in the memory unit 1102.

[0101] The storage unit 1102 is configured to include, for example, memory such as ROM or RAM. The storage unit 1102 stores various information such as programs for performing various operations described later, communication parameters for wireless communication, and data processed or processed by the base station 1001. In addition to memory such as ROM or RAM, the storage unit 1102 may also be configured to include storage media such as flexible disks, hard disks, optical disks, magneto-optical disks, CD-ROMs, CD-Rs, magnetic tapes, non-volatile memory cards, and DVDs.

[0102] The message generation processing unit 1103 is composed of a general-purpose processor such as a CPU (for example, implemented as a program), a dedicated processing circuit, etc. The message generation processing unit 1103 generates signals and messages to be transmitted to neighboring UEs, including neighboring relay UEs (for example, relay UE 103). Such signals and messages include discovery signals, request messages, etc.

[0103] The message analysis processing unit 1104 is composed of a general-purpose processor such as a CPU (for example, implemented as a program), a dedicated processing circuit, etc. The message analysis processing unit 1104 analyzes signals and messages transmitted from neighboring UEs, including neighboring relay UEs (for example, relay UE 1003). Such signals and messages include discovery signals, response signals to discovery signals, request messages, response messages, cancel request messages, etc.

[0104] The wireless communication unit 1105 includes hardware (e.g., an RF chip, a baseband chip, etc.) for performing wireless communication compliant with the 3GPP cellular communication standard. The wireless communication unit 1105 may also be composed of a general-purpose processor such as a CPU (for example, implemented as a program). The wireless communication unit 1105 controls one or more corresponding antennas to transmit and receive wireless signals. The wireless communication unit 1105 communicates information wirelessly with neighboring UEs, including neighboring relay UEs. The wireless communication unit 1105 performs the transmission process of messages generated by the message generation processing unit 1103, and the reception process of messages transmitted from neighboring UEs, including neighboring relay UEs.

[0105] The communication unit 1106 communicates with the core network (not shown). The core network has functional units such as UPF (User Plane Function) and AMF (Access and Mobility Function). The communication unit 1106 communicates with the UPF, AMF, etc. in the core network. The core network exchanges C-Plane (Control-Plane) and U-Plane (User-Plane) data with base stations and other equipment. Control information for communication control of equipment and base stations is communicated in the C-Plane. Data such as images, videos, and audio data from websites used by users is communicated in the U-Plane.

[0106] [Processing of the device] Next, referring again to Figure 10, the processing of the communication device according to this embodiment will be explained using Figures 12 and 13. Figure 12 is a sequence diagram showing an example of operation of the communication device according to the third embodiment. Figure 13 is a flowchart showing an example of operation of the communication device according to the third embodiment.

[0107] Base station 1001 performs discovery when it wants to communicate with target UE 1002. Initially, base station 1001, target UE 1002, and relay UE 1003 are located in the positional relationship shown in Figure 10(a), for example. Base station 1001 searches for target UE 1002, but since it cannot find target UE 1002 within base station 1001's communication range, it searches for a nearby relay. As a result of the relay search, base station 1001 finds relay UE 1003. Then, relay UE 1003 searches for target UE 1002 and finds target UE 1002 within relay UE 1003's communication range. Therefore, base station 1001 decides to communicate with target UE 1002 via relay UE 1003.

[0108] Subsequently, as the base station 1001 and target UE 1002 move closer together, and the relay UE 1003 moves further away from the base station 1001 and target UE 1002, the positions and communication range of the base station 1001, target UE 1002, and relay UE 1003 change. This change is shown, for example, in Figure 10(b).

[0109] The operation example shown in Figure 12 is the same as the operation example shown in Figure 4, except that the source UE101 shown in Figure 4 is replaced with base station 1001. Similarly, the operation example shown in Figure 13 is the same as the operation example shown in Figure 5. Therefore, the processing of the device according to the third embodiment will not be explained.

[0110] In the third embodiment, the target UE 1002 can send a request message cancellation, enabling direct communication between the base station 1001 and the target UE 1002 without going through the relay UE 1003. As a result, the immediacy between the base station 1001 and the target UE 1002 is improved. Furthermore, the connection waiting time of the relay UE 1003 is reduced, and the connection between the relay UE 1003 and the target UE 1002 becomes unnecessary, thereby reducing the time and frequency resources between the relay UE 1003 and the target UE 1002.

[0111] Although this embodiment describes an example where there is one relay UE, this embodiment can also be applied when there are two or more relay UEs by combining it with the second embodiment.

[0112] <Other Embodiments> This disclosure can also be implemented by supplying a program that implements one or more of the functions of each of the embodiments described above to a system or device via a network or storage medium, and by having one or more processors in the computer of that system or device read and execute the program. Furthermore, this disclosure can also be implemented by a circuit (e.g., an ASIC or FPGA) that implements one or more functions.

[0113] This disclosure is not limited to the embodiments described above, and various modifications and variations are possible without departing from the spirit and scope of this disclosure.

[0114] The names of the functional units, messages, parameters, fields, etc., described in the embodiments described above are examples and may be changed to other names.

[0115] The order of the processing procedures, sequences, flowcharts, etc., in the embodiments described above is not limited to the specific order presented, and may be rearranged or additional steps may be added, as long as they do not contradict each other.

[0116] The matters described in the above embodiments may be incorporated into other embodiments, insofar as they do not contradict each other.

[0117] Furthermore, the following additional information is disclosed regarding the above embodiments.

[0118] [Note 1] A communication device, A receiving means for receiving a first message related to relay communication from a relay device, A transmission means for sending a second message related to relay communication, It has, A communication device in which, if the first message includes information for identifying the communication device, and the second message includes information for identifying the first message or the relay device, the second message indicates that relay communication using the relay device is not performed in the communication performed by the communication device.

[0119] [Note 2] The communication device as described in Appendix 1, wherein if the first message includes information for identifying the communication device, and the second message does not include the first message or information for identifying the relay device, the transmitting means transmits a third message to the relay device indicating that relay communication using the relay device is performed in the communication performed by the communication device.

[0120] [Note 3] The relay device is one of the relay devices connected in multiple stages, and is a communication device as described in Appendix 1 or 2.

[0121] [Note 4] The first message includes information indicating that relay communication using the relay device is possible, as described in any of the appendices 1 to 3.

[0122] [Note 5] If the first message includes information for identifying the communication device, and the second message includes information for identifying the first message or the relay device, the transmitting means transmits the second message by broadcast or transmits it to the relay device by unicast, according to any of the appendices 1 to 4.

[0123] [Note 6] The communication device is a communication device that operates as a terminal, and the relay device is a terminal-to-terminal relay device or a base station-to-terminal relay device, as described in any of Appendix 1 to 5.

[0124] [Note 7] If the first message includes information for identifying the communication device, a decision means determines, based on the received power or received quality of the first message, that relay communication using the relay device will not be performed in the communication performed by the communication device. A communication device as described in any of the appendices 1 to 6, further comprising the above.

[0125] [Note 8] If the first message includes information for identifying the communication device, a decision means determines, based on the information for identifying the first message, that relay communication using the relay device will not be performed in the communication performed by the communication device. A communication device as described in any of the appendices 1 to 6, further comprising the above.

[0126] [Note 9] It is a relay device, A transmitting means for transmitting a first message related to relay communication, A receiving means for receiving a second message related to relay communication from a communication device, It has, If the first message includes information for identifying the communication device, and the second message includes information for identifying the first message or the relay device, the second message indicates that relay communication using the relay device will not be performed in the communication performed by the communication device.

[0127] [Note 10] The relay device according to Appendix 9, wherein if the first message includes information for identifying the communication device, and the second message does not include the first message or information for identifying the relay device, the receiving means receives a third message from the communication device indicating that relay communication using the relay device is performed in the communication performed by the communication device.

[0128] [Note 11] The relay device is one of the relay devices connected in multiple stages, as described in Appendix 9 or 10.

[0129] [Note 12] The relay device according to any one of appendices 9 to 11, wherein the first message includes information indicating that relay communication using the relay device is possible.

[0130] [Note 13] The communication device is a relay device that operates as a terminal, and the relay device is a terminal-to-terminal relay device or a base station-to-terminal relay device, as described in any of Appendix 9 to 12.

[0131] [Note 14] A communication system having a communication device and a relay device, The relay device transmits a first message relating to relay communication. The communication device receives the first message from the relay device, The communication device transmits a second message relating to relay communication. The relay device receives the second message from the communication device, A communication system in which, if the first message includes information for identifying the communication device, and the second message includes information for identifying the first message or the relay device, the second message indicates that relay communication using the relay device is not performed in the communication performed by the communication device.

[0132] [Note 15] The process involves a communication device receiving a first message related to relay communication from a relay device, The communication device transmits a second message relating to relay communication, Includes, A control method in which, if the first message includes information for identifying the communication device, and the second message includes information for identifying the first message or the relay device, the second message indicates that relay communication using the relay device is not performed in the communication performed by the communication device.

[0133] [Note 16] The relay device transmits a first message related to relay communication, The relay device receives a second message related to relay communication from the communication device, Includes, A control method in which, if the first message includes information for identifying the communication device, and the second message includes information for identifying the first message or the relay device, the second message indicates that relay communication using the relay device is not performed in the communication performed by the communication device.

[0134] [Note 17] A program for causing a computer to perform the control methods described in Appendix 15 or 16. [Explanation of symbols]

[0135] 101, 102, 701, 702, 1002 Remote UE 103, 703, 704, 1003 Relay UE 1001 base station 201, 301, 1101 Control Units 202, 302, 1102 Storage section 203, 303, 1103 Message generation processing unit 204, 304, 1104 Message parsing processing unit 205, 305, 1105 Wireless Communication Section 306 Sidelink Relay Processing Unit 1106 Communications Department

Claims

1. A communication device, A receiving means for receiving a first message related to relay communication from a relay device, A transmission means for sending a second message related to relay communication, It has, A communication device in which, if the first message includes information for identifying the communication device, and the second message includes information for identifying the first message or the relay device, the second message indicates that relay communication using the relay device is not performed in the communication performed by the communication device.

2. The communication device according to claim 1, wherein if the first message includes information for identifying the communication device, and the second message does not include the first message or information for identifying the relay device, the transmitting means transmits a third message to the relay device indicating that relay communication using the relay device is performed in the communication performed by the communication device.

3. The communication device according to claim 1, wherein the relay device is one of several relay devices connected in a multi-stage configuration.

4. The communication device according to claim 1, wherein the first message includes information indicating that relay communication using the relay device is possible.

5. The communication device according to claim 1, wherein if the first message includes information for identifying the communication device, and the second message includes information for identifying the first message or the relay device, the transmitting means transmits the second message by broadcast or by unicast to the relay device.

6. The communication device according to claim 1, wherein the communication device is a communication device that operates as a terminal, and the relay device is a terminal-to-terminal relay device or a base station-to-terminal relay device.

7. If the first message includes information for identifying the communication device, a decision means determines, based on the received power or received quality of the first message, that relay communication using the relay device will not be performed in the communication performed by the communication device. The communication device according to claim 1, further comprising the following:

8. If the first message includes information for identifying the communication device, a decision means determines, based on the information for identifying the first message, that relay communication using the relay device will not be performed in the communication performed by the communication device. The communication device according to claim 1, further comprising the following:

9. It is a relay device, A transmitting means for transmitting a first message related to relay communication, A receiving means for receiving a second message related to relay communication from a communication device, It has, If the first message includes information for identifying the communication device, and the second message includes information for identifying the first message or the relay device, the second message indicates that relay communication using the relay device will not be performed in the communication performed by the communication device.

10. The relay device according to claim 9, wherein if the first message includes information for identifying the communication device, and the second message does not include the first message or information for identifying the relay device, the receiving means receives a third message from the communication device indicating that relay communication using the relay device is performed in the communication performed by the communication device.

11. The relay device according to claim 9, wherein the relay device is one of several relay devices connected in a multi-stage configuration.

12. The relay device according to claim 9, wherein the first message includes information indicating that relay communication using the relay device is possible.

13. The relay device according to claim 9, wherein the communication device is a relay device that operates as a terminal, and the relay device is a terminal-to-terminal relay device or a base station-to-terminal relay device.

14. A communication system having a communication device and a relay device, The relay device transmits a first message relating to relay communication. The communication device receives the first message from the relay device, The communication device transmits a second message relating to relay communication. The relay device receives the second message from the communication device, A communication system in which, if the first message includes information for identifying the communication device, and the second message includes information for identifying the first message or the relay device, the second message indicates that relay communication using the relay device is not performed in the communication performed by the communication device.

15. The process involves a communication device receiving a first message related to relay communication from a relay device, The communication device transmits a second message relating to relay communication, Includes, A control method in which, if the first message includes information for identifying the communication device, and the second message includes information for identifying the first message or the relay device, the second message indicates that relay communication using the relay device is not performed in the communication performed by the communication device.

16. The relay device transmits a first message related to relay communication, The relay device receives a second message related to relay communication from the communication device, Includes, A control method in which, if the first message includes information for identifying the communication device, and the second message includes information for identifying the first message or the relay device, the second message indicates that relay communication using the relay device is not performed in the communication performed by the communication device.

17. A program for causing a computer to execute the control method described in claim 15 or 16.

Images