Relay device and terminal device for forwarding route-specified signals

Abstract

A relay device that relays communication between a base station device and a terminal device receives a signal sent for communication from another device, determines a forwarding destination of the data based on identification information included in the received signal and indicating a route for forwarding the data included in the received signal between the base station device and the terminal device, and transmits a signal including the data to the determined forwarding destination device. When the route indicated by the identification information does not include the relay device, the relay device determines a specific device as the forwarding destination device.

Description

Technical Field

[0001] The present invention relates to a relay device and a terminal device, and to a relay communication control technology for forwarding a signal designated by a route. Background Art

[0002] In the 3rd Generation Partnership Project (3GPP), the formulation of the fifth generation (5G) cellular communication standard, the NR (New Radio) standard, has been developed. In addition, in the NR standard, as a technology for a base station device to use wireless resources for communicating with a terminal device to perform backhaul communication, IAB (Integrated Access and Backhaul) is under study. In IAB, for example, a line between a 5G base station device (IAB donor) directly connected to a core network, a relay device (IAB node) that provides wireless access to a terminal device, and a line between IAB nodes are established wirelessly. The IAB donor manages the IAB nodes that are directly or indirectly connected to its own device, and can identify which IAB node a terminal device that is not directly connected to its own device is connected to. Moreover, the IAB donor is formed, for example, to send a packet containing data destined for a terminal device to an IAB node to which the terminal device is connected, and the IAB node sends a wireless signal containing the data to the terminal device. Multiple routes can be set between the IAB donor and the IAB node.

[0003] Figure 1 An example of a wireless communication system used by IAB is shown. Figure 1In an example, there is, for example, a 5G base station device 101 connected to the core network, a relay device A102 that can be directly connected to the base station device 101, and relay devices B103 to F107 that are connected to the base station device 101 at least via the relay device A102. In one example, the base station device 101 is an IAB donor and the relay device is an IAB node. Furthermore, when the base station device 101 communicates with the terminal device 111, for example, packets are forwarded in the order from the base station device 101 to the relay device A102 and from the relay device A102 to the relay device B103, and a wireless signal containing data is transmitted from the relay device B103 to the terminal device 111. Similarly, the wireless signal transmitted from the terminal device 111 is received by the relay device B103, and the packet containing the data is transmitted to the base station device 101 via the relay device A102. Furthermore, multiple routes can be set between the base station device 101 and a relay device. For example, three routes can be set between the base station device 101 and the relay device F107: a route via [relay device A102, relay device B103, relay device D105], a route via [relay device A102, relay device C104, relay device D105], and a route via [relay device A102, relay device C104, relay device E106].

[0004] When multiple routes can be set, the base station device determines the route to be used between the relay device and the terminal device based on the relay device that is directly communicating with the terminal device. For example, the route to be used is determined based on a predetermined benchmark such as making the load of multiple routes uniform. In non-patent document 1, the relayed packet contains the identification information of the node containing the end point of the relay (for example, the base station device in the uplink and the relay device that directly communicates with the terminal device in the downlink) and the identification information of the route to be used. Based on the above, each relay device can identify to which node the received packet should be sent based on the identification information of the route.

[0005] Prior art literature

[0006] Non-patent literature

[0007] Non-Patent Document 1: 3GPP Contribution, R2-1908363, May 2019 Summary of the Invention

[0008] Problems to be solved by the invention

[0009] Imagine that communication is impossible in a part of the relay route. For example, Figure 1The radio quality between relay device A102 and relay device B103 deteriorates, and communication may become impossible. In this case, relay device A102 may not be able to send the packet received from base station device 101, which includes identification information of the route passing through relay device B103, to relay device B103, causing packet forwarding failure.

[0010] Means used to solve problems

[0011] The present invention provides a technology for appropriately forwarding a signal to a destination in communications using a relay transmission path.

[0012] According to one embodiment of the present invention, a relay device relays a signal from a base station device or a terminal device to a destination device, wherein the relay device includes: a receiving unit configured to receive the signal; and a decision unit configured to decide, based on destination information indicating the destination device included in the received signal, a device to which the relay device has established a connection as the next-hop device to which the signal will be forwarded, when the next-hop to which the signal will be forwarded cannot be identified based on route identification information included in the received signal indicating a route through which data included in the received signal will be forwarded.

[0013] According to one embodiment of the present invention, there is provided a terminal device comprising: a communication device configured to send / receive signals to / from a relay device, the relay device relaying signals from a base station device or a terminal device to a destination device, wherein the relay device receives the signal and, when the next hop to which the signal is to be forwarded cannot be identified based on route identification information included in the received signal and indicating a route through which data included in the received signal is to be forwarded, determines a device to which the relay device has established a connection as the next hop device to which the signal is to be forwarded based on destination information included in the received signal and indicating the destination device.

[0014] Effects of the Invention

[0015] According to the present invention, it is possible to appropriately forward a signal to a destination in communications using a relay transmission path.

[0016] Other features and advantages of the present invention will become clear from the following description with reference to the accompanying drawings. In addition, in the accompanying drawings, the same or similar structures are marked with the same reference numerals. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the present invention and, together with the description, serve to explain the principles of the present invention.

[0018] Figure 1 This is a diagram showing an example configuration of a wireless communication system.

[0019] Figure 2 This is a diagram showing an example of the hardware configuration of a relay device.

[0020] Figure 3 This is a diagram showing an example of the functional configuration of a relay device.

[0021] Figure 4 This is a diagram showing an example of the flow of processing executed by the relay device.

[0022] Figure 5 This is a diagram showing an example of the functional configuration of a relay device.

[0023] Figure 6 This is a diagram showing an example of the flow of processing executed by the relay device. DETAILED DESCRIPTION

[0024] The following embodiments are described in detail with reference to the accompanying drawings. The following embodiments do not limit the inventions described herein. Furthermore, not all combinations of features described in the embodiments are essential to the invention. Any combination of two or more of the multiple features described in the embodiments may be used. Identical or similar components are denoted by the same reference numerals, and duplicate descriptions are omitted.

[0025] <First embodiment>

[0026] (System Configuration)

[0027] The wireless communication system of this embodiment has the above Figure 1Such a configuration. In this system, as described above, it is possible to perform communication between the base station device 101 (IAB donor) and the terminal devices 111 to 112 via a relay route including one or more relay devices (IAB nodes). A plurality of such relay routes can be set, and the base station device can decide which route to use for communication. For example, between the base station device 101 and the relay device F107, as described above, three routes can be set: a first route via [relay device A102, relay device B103, relay device D105], a second route via [relay device A102, relay device C104, relay device D105], and a third route via [relay device A102, relay device C104, relay device E106]. The base station device 101, for example, decides to perform communication between the terminal devices 112 via the relay device F107, and further selects a route between the base station device 101 and the relay device F107 from among the three routes mentioned above.

[0028] Furthermore, new routes are set, for example, when a base station establishes a connection with a newly installed relay device, or when a relay device establishes a connection with another newly installed relay device. For example, a route from base station 101 to relay device F107 via [relay device A102, relay device C104, relay device E106] is set due to the newly installed relay device F107 and its establishment of a connection with relay device E106. Furthermore, a route from base station 101 to relay device F107 via [relay device A102, relay device B103, relay device D105] and a route to relay device F107 via [relay device A102, relay device C104, relay device D105] are set due to the establishment of a connection between relay device F107 and relay device D105. Furthermore, once a route is set, the identification information of the route is notified to the relay devices included in the route. In the identification information, information that identifies the devices included in the corresponding route and information that indicates the order in which the signal should be forwarded between these devices are associated and stored in each relay device. Each relay device can determine the device (for example, another relay device, base station device) of the forwarding destination of the signal based on the identification information. In addition, "forwarding" here can be a non-reproduction relay that amplifies the received signal as it is and sends it to other devices, but in the following, it is assumed that it is used for a reproduction relay that decrypts the received signal and extracts the data, generates a transmission signal based on the data, and sends it to the forwarding destination device. In addition, "forwarding signal" means forwarding the data contained in the signal, and as described below, the header information such as the route identification information does not need to be changed.

[0029] Furthermore, when multiple routes are established between two relay devices, the route identification information may include information identifying the route between the relay devices. For example, when two routes, route α and route β, are established between relay device A 102 and relay device B 103, the route identification information may include information identifying the route to be used (route α or route β).

[0030] In one example, in this embodiment, base station apparatus 101 is communicating with terminal apparatus 112. For this communication, a first route via [relay apparatus A102, relay apparatus B103, and relay apparatus D105] is selected. In this case, a signal transmitted from base station apparatus 101 to terminal apparatus 112 is first transmitted to relay apparatus A102, which receives the signal and forwards it to relay apparatus B103. Relay apparatus B103 then forwards the signal received from relay apparatus A102 to relay apparatus D105, and relay apparatus D105 forwards the signal received from relay apparatus B103 to relay apparatus F107. Relay apparatus F107 then transmits the data contained in the received signal to terminal apparatus 112. Furthermore, in one example, communication between base station apparatuses and relay apparatuses, communication between relay apparatuses, and communication between relay apparatuses and terminal apparatuses is performed wirelessly.

[0031] In the following, an example is described in which the base station apparatus 101 communicates with the terminal apparatus via a plurality of relay apparatuses. However, the base station apparatus 101 can of course communicate with the terminal apparatus via a single relay apparatus or without any relay apparatus.

[0032] When base station device 101 transmits a signal via the first route described above, the signal includes destination information identifying relay device F107, which is communicating directly with terminal device 112, as the destination, and route identification information indicating the first route through which the signal should be forwarded. If the base station device 101 then checks the destination information and determines that its own device is the destination, the relay device included in the first route transmits a wireless signal containing the forwarded data to the terminal device based on the terminal device information included in the forwarded signal. If the base station device 101 then checks the destination information and determines that its own device is not the destination, the relay device identifies the device to which the signal should be forwarded based on the route identification information. For example, in the first route described above, upon receiving a signal from relay device A102, relay device B103 checks the destination information included in the signal and determines that its own device is not the destination (relay device F107). Relay device B103 then identifies relay device D105 as the forwarding destination based on the route identification information indicating the first route and forwards the received signal to relay device D105. Furthermore, when receiving a signal from relay device D 105 on the first route, relay device B 103 checks the destination information included in the signal and determines that its own device is not the destination (base station device 101). Relay device B 103 then identifies relay device A 102 as the forwarding destination based on the route identification information representing the first route and forwards the received signal to relay device A 102. This enables communication between base station device 101 and a terminal device using the relay route.

[0033] Here, for example, assume that when base station apparatus 101 transmits a signal including destination information indicating relay device F107 and route identification information indicating a first route to relay device A102, relay device A102 may find itself unable to transmit the signal to relay device B103. This situation may occur, for example, when an RLF (Radio Link Failure) occurs in the radio link between relay devices A102 and B103, causing the load on the radio link to become high, making communication with sufficient quality impossible. In this case, relay device A102 can notify base station apparatus 101 that the first route cannot be used and that a different route should be used. Base station apparatus 101 can then retransmit the signal using, for example, the second or third route described above, without using the radio link between relay devices A102 and B103. On the other hand, for example, in a route in use, if it is determined that a wireless link cannot be used at a relay device close to the destination, if the base station device 101 is notified that the route cannot be used, the time it takes for the signal to reach the relay device whose wireless link cannot be used is added, and the time it takes for the notification to reach the base station device 101 is added, thereby lengthening the time it takes for the signal to be sent via another route.

[0034] Therefore, in this embodiment, in addition to or in lieu of the aforementioned notification, the relay device forwards the signal to another destination to prevent communication delays caused by sending the signal via an alternate route. For example, if relay device A 102 determines that it cannot use the wireless link with relay device B 103, the signal is forwarded to relay device C 104 instead of relay device B 103. However, in this case, relay device C 104 does not include itself in the route identified by the route identification information included in the received signal, and therefore cannot determine the forwarding destination device based on this route identification information.

[0035] Therefore, in this embodiment, when the route identified by the route identification information included in the received signal does not include the relay device itself, the relay device determines a specific device as the signal's forwarding destination. For example, relay device C104 determines either relay device D105 or relay device E106, to which it has established a connection, as the forwarding destination. For example, relay device C104 can select a route connected to relay device F107 based on the route information stored within itself and the destination information, and determine the device on that route to which relay device C104 should forward the signal as the forwarding destination.

[0036] Alternatively, the base station 101 may pre-set whether the relay C104 can determine the forwarding destination. In this case, the relay C104 can determine the forwarding destination of the received signal or forward the received signal and discard it according to the pre-set settings.

[0037] The relay device C104 may also determine a specific device as the predetermined forwarding destination device. In one example, the relay device C104 pre-sets any device as the predetermined forwarding destination device based on the fact that there are multiple devices that are candidates for the forwarding destination of the signal from the base station device 101. For example, the relay device C104 can pre-set any device (e.g., relay device D105) as the predetermined forwarding destination device based on the fact that connections have been established with the relay device D105 and the relay device E106 (e.g., based on the fact that Dual Connectivity has been started). Which device is set as the predetermined forwarding destination device is determined, for example, based on an instruction from the base station device 101. In addition, the relay device C104 may determine the predetermined forwarding destination device without relying on an instruction from the base station device 101. In addition, the predetermined forwarding destination device does not need to be just one, and multiple predetermined forwarding destination devices may be pre-set. In this case, the relay device C104 may maintain information with priority rankings for each of the multiple predetermined forwarding destination devices. The relay device C104 can then, for example, determine a specific device to which the forwarding is actually to be performed based on the priority ranking from among the devices that are included in the route to the destination indicated by the destination information and that are included in the predetermined forwarding destination devices. For example, the relay device C104 can determine as the specific device the device with the highest priority ranking among the predetermined forwarding destination devices. Alternatively, the relay device C104 can determine as the specific device a device that has a higher priority ranking than the predetermined ranking among the predetermined forwarding destination devices.

[0038] Furthermore, even if the route indicated by the route identification information included in the received signal does not include the relay device itself, relay device C104 may still be able to determine that its own device includes a device capable of transmitting a signal. For example, since the first route described above includes relay device D105, relay device C104 has established a connection with relay device D105. Therefore, in this case, relay device C104 can determine relay device D105 as the specific device to forward the signal. Furthermore, when performing the above-described processing, base station device 101 can notify each relay device of identification information related to all routes connecting the relay device to other devices, as well as information indicating the devices included in the routes. Furthermore, base station device 101 may also notify each relay device of route identification information related to all routes including the relay device itself, as well as information indicating the devices included in the routes for all other relay devices to which the relay device is connected, in addition to all routes including the relay device itself. Thus, when receiving a signal containing route identification information related to a route that does not include its own device, each relay device can forward the signal to the device if a connection is established with its own device and a device included in the route indicated by the route identification information exists. In addition, the relay device can limit the devices that can be selected as the forwarding destination by determining whether the signal is an uplink signal or a downlink signal. That is, for example, when relay device C104 receives a downlink signal from relay device A102, it excludes other devices that exist in the uplink direction of relay device A102 and other devices from the selection of a specific device. Thus, by forwarding and returning the signal to the device that sent the signal, it is possible to prevent the terminal device from being unable to be delivered. In addition, at this time, when the base station device 101 or relay device F107 (the destination of the signal) is specified in the destination information, the relay device C104 can use the destination information to determine whether the signal is an uplink signal or a downlink signal. Furthermore, there can also be an embodiment in which the relay device C104 determines whether the signal is an uplink signal or a downlink signal based on the route indicated by the route identification information.

[0039] Furthermore, relay device C104 can determine a specific device to forward a signal based on the usage frequency of each route in the direction opposite to the direction in which the signal was transmitted (i.e., uplink communication if the signal is a downlink signal, and downlink communication if the signal is an uplink signal). Specifically, since routes with a higher usage frequency in the direction opposite to the direction in which the signal was forwarded can be considered to indicate good wireless link conditions, such as radio quality, the specific device can be determined to use those routes. For example, relay device C104 determines a first usage frequency for a route from relay device F107, through relay device D105, and through relay device C104, and a second usage frequency for a route from relay device F107, through relay device E106, and through relay device C104. Relay device C104 can then determine relay device D105 as the specific device if the first usage frequency is higher, and determine relay device E106 as the specific device if the second usage frequency is higher. Alternatively, when the difference between the first usage frequency and the second usage frequency is equal to or smaller than a predetermined value, the relay device C104 may determine a specific device as a predetermined forwarding destination device that is set in advance, for example.

[0040] Furthermore, if the route identified by the route identification information included in the received signal does not include the relay device itself, the relay device C104 forwards the signal as described above and notifies the base station device 101 or relay device F107 (the signal transmission source) that the route cannot be used. This notification allows the relay device C104 to urge the signal transmission source device to use another route for communication.

[0041] Alternatively, the period during which the relay device C104 forwards the signal may be limited to a certain period after communication with the source device. In this case, after the certain period, the relay device C104 does not determine the forwarding destination device. If the route indicated by the route identification information included in the received signal does not include its own device, the relay device C104 does not forward the signal and discards it.

[0042] Furthermore, if the route identified by the route identification information contained in the received signal does not include its own device, relay device C104 may also modify the route identification information contained in the signal. For example, relay device C104 may replace the route identification information contained in the signal with identification information corresponding to a route that includes the device to which the signal is forwarded. This allows the device receiving the signal from relay device C104 to determine the signal's forwarding destination based on this replaced identification information. For example, when relay device C104 receives a signal containing route identification information corresponding to the first route described above, it determines the forwarding destination device as described above. Relay device C104 then replaces the route identification information contained in the received signal with identification information corresponding to the route that includes the forwarding destination device. For example, when relay device D105 is set as the forwarding destination device, relay device C104 replaces the route identification information with identification information corresponding to the second route described above. When relay device E106 is set as the forwarding destination device, relay device C104 replaces the route identification information with identification information corresponding to the third route described above. Thus, relay device D105 or relay device E106 receiving the signal forwarding can use this replaced identification information to decide to forward the signal to relay device F107. Furthermore, when relay device C104 sets relay device D105 as the forwarding destination, it can retain the route identification information corresponding to the first route. That is, since the first route does not include relay device C104 but does include relay device D105, the route identification information can be retained even when relay device D105 is set as the forwarding destination. As described above, forwarding of signals from relay device D105 onwards can maintain the route set by base station device 101.

[0043] In addition, the relay device C104 can, for example, replace the route identification information with predetermined information. The predetermined information can be information indicating the route used for forwarding the undetermined signal. In addition, instead of replacing the route identification information with predetermined information, the relay device C104 can also delete the route identification information. That is, by not including the route identification information, the fact that the route is undetermined can be indicated by default. In the above case, since the relay device that receives the signal forwarded by the relay device C104 cannot determine the forwarding destination of the signal by using the route identification information, the device that determines the forwarding destination forwards the signal to the device of the determined forwarding destination, as described with reference to the relay device C104 mentioned above.

[0044] Furthermore, the above example describes an example in which relay device C104 changes the route identification information when the route indicated by the route identification information included in the received signal does not include its own device. However, this is not limiting. Specifically, in the above example, relay device A102 does not forward the signal to relay device B103, to which it should have forwarded it. Instead, because it transmits the signal to relay device C104, relay device C104 receives a signal containing route identification information corresponding to a route that does not include its own device. In contrast, relay device A102 can change the route identification information without determining the signal's forwarding destination based on the route indicated by the route identification information. As in the above example, this change can involve replacing or deleting the route identification information based on predetermined information. In this case, when relay device C104 receives the signal forwarded by relay device A102, since the signal's forwarding destination cannot be determined based on the route identification information, it determines the forwarding destination as described above and forwards the signal to the device determined as the forwarding destination. Alternatively, relay device A102 may replace the route identification information with identification information corresponding to the route that includes relay device C104, the signal's forwarding destination. In this case, when relay device C104 receives a signal forwarded by relay device A102, it can identify the route that includes itself using the route identification information and thus determine the signal's forwarding destination based on that route. Furthermore, relay device A102 may forward the signal without changing the route identification information, for example, if it has established a wireless link with relay device D105 included in the first route indicated by the route identification information and has decided to forward the signal directly to relay device D105.

[0045] Furthermore, when the relay device C104 determines the device to which the signal is to be forwarded and multiple lines are established between the relay device and the forwarding destination device, the relay device C104 can determine the line to be used for forwarding, for example, by randomly selecting from available lines. Furthermore, the selection of the line to be used for forwarding can be based on predetermined settings, rules, the level of line quality (QoS), or the lightness of the load (the number of nodes or UEs used, or the low level of wireless resource usage).

[0046] In the above description, attention is paid to relay device A102 and relay device C104, but all relay devices may be configured to be able to execute the processing executed by relay device A102 and the processing executed by relay device C104 described above.

[0047] (Device Configuration)

[0048] Next, use Figure 2An example of the hardware configuration of a relay device that performs the above-described processing will be described. In one example, these devices include a processor 201, ROM 202, RAM 203, storage device 204, and communication circuit 205. Processor 201 is a computer that includes one or more processing circuits, such as a general-purpose CPU (Central Processing Unit) or an ASIC (Application-Specific Integrated Circuit). It performs the overall processing of the relay device and the above-described individual processes by reading and executing programs stored in ROM 202 and storage device 204. ROM 202 is a read-only memory that stores information such as programs and various parameters related to the processes performed by the relay device. RAM 203 functions as a workspace for processor 201 while executing programs and is also a random access memory for temporary information storage. Storage device 204 is, for example, a removable external storage device. Communication circuit 205 is, for example, circuitry for wireless communication. The relay device includes, for example, baseband circuitry and RF circuitry for cellular communication, as well as an antenna, serving as communication circuit 205 for communicating with base stations, other relay devices, and terminal devices. In addition, the communication circuit 205 of the relay device may also include, for example, a circuit for performing wireless or wired communication, and the wireless or wired communication is used for signal transmission for control, etc. Figure 2 , one communication circuit 205 is shown in the figure, but each device may have multiple communication circuits.

[0049] Figure 3 This figure shows an example of the functional configuration of a relay device. The relay device may include, for example, a communication unit 301, a route information determination unit 302, a forwarding destination determination unit 303, and a forwarding control unit 304. Furthermore, the relay device may also include a route information change unit 305 and a forwarding destination change notification unit 306. These functional units, for example, can be implemented by the processor 201 executing programs stored in the ROM 202.

[0050] According to cellular communication standards, the communication unit 301 is a functional unit for wirelessly communicating with base stations, other relay devices, and terminal devices. The route information determination unit 302 determines the route along which signals received from base stations and other relay devices will be forwarded, based on identification information included in the signal. The forwarding destination determination unit 303 determines the device to which the signal should be forwarded based on the route determined by the route information determination unit 302. For example, if the determined route includes the device itself, the forwarding destination determination unit 303 determines the device to which the signal should be forwarded next along that route. Furthermore, if communication over the wireless link between the device designated as the forwarding destination based on the determined route is not possible, the forwarding destination determination unit 303 may determine to forward the signal to a device other than the forwarding destination. Furthermore, if the determined route does not include the device itself, the forwarding destination determination unit 303 can determine a specific device as the forwarding destination. The method for determining the specific device is the same as described above and will not be repeated here. The forwarding control unit 304 controls the communication unit 301 to forward the received signal to the device at the forwarding destination determined by the forwarding destination determination unit 303. Furthermore, in this case, if the signal is forwarded to a device different from the next forwarding destination device in the route determined by the identification information included in the received signal, the route information change unit 305 can change the identification information. The method for changing the identification information is the same as described above and will not be repeated here. If the signal is forwarded to a device different from the next forwarding destination device in the route determined by the identification information included in the received signal, the forwarding destination change notification unit 306 transmits a signal to the base station apparatus 101 notifying the user that the route cannot be used. Furthermore, the forwarding destination change notification unit 306 can notify the device that determined the route that the route cannot be used. For example, regarding a signal sent from relay device F107, when base station device 101 decides on the route, destination change notification unit 306 sends a notification that the route cannot be used to base station device 101, and when relay device F107 decides on the route, destination change notification unit 306 sends the notification to relay device F107.

[0051] (Processing Flow)

[0052] use Figure 4 The flow of processing executed by the relay device will be briefly described. Figure 4The processing is performed, for example, by a base station device, a relay device in the middle of a route between relay devices directly connected to a terminal device (i.e., a relay device not at the end of the route). In this processing, first, the relay device receives a signal from another device (e.g., a base station device or another relay device) (S401). The relay device parses the received signal, extracts the destination information indicating the device of the destination contained in the signal, and the route identification information indicating the route, and determines the route to which the signal should be forwarded based on the route identification information (S402). Then, the relay device decides the device to which the destination is to be forwarded based on the determined route (S403).

[0053] For example, if the determined route does not include its own device, the relay device will determine the device to which the signal should be forwarded after its own device in the route as the forwarding destination device. In this case, for example, if a failure occurs in the wireless link between the device at the next forwarding destination in the route, the relay device can determine that communication with the forwarding destination device should not be carried out. In this case, the relay device can determine other devices not included in the route as the forwarding destination of the signal. In addition, if the determined route does not include its own device, the relay device can independently determine the forwarding destination device. Since the method for determining the forwarding destination device in these cases is the same as that described above, the description here is omitted.

[0054] The relay device then forwards the signal received in S401 to the device at the forwarding destination determined in S403 (S405). At this time, if the signal is forwarded to a device not included in the route specified by the route identification information included in the signal, or if the relay device itself is not included in the route, the relay device changes the route identification information (S404). The process for changing the route identification information is the same as described above, so its description is omitted here. Furthermore, the process in S404 may not be performed. Furthermore, if the signal is forwarded to a device not included in the route specified by the route identification information included in the signal, or if the relay device itself is not included in the route, the relay device may notify the base station device 101 that the route cannot be used (S406). Furthermore, since it can be assumed that, for example, if the route identification information is determined to have been changed to predetermined information in the received signal, the relay device notifies the base station device 101 that the route cannot be used after the change, the notification in S406 may not be performed. Furthermore, if the forwarding destination is not changed, the notification in S406 is not performed. Furthermore, in S406, notification is made to the device that initially determined the signal forwarding route. For example, when relay device F107 transmits a signal to base station device 101, if relay device F107 determined the route, notification is made to relay device F107; if base station device 101 determined the route, notification is made to base station device 101.

[0055] Thus, according to the relay device described above, when it is difficult to forward the signal along a route, the signal can be forwarded to the destination device by deviating from the route and continuing to forward the signal based on the route identification information contained in the signal. Furthermore, by appropriately selecting the forwarding destination device as described above, efficient signal forwarding can be achieved. Furthermore, by changing the route identification information representing the route in the forwarding signal in conjunction with a change in the forwarding destination device, the forwarding destination device can be easily determined. Furthermore, when the forwarding destination is changed, by notifying the user that the initially set route cannot be used, repeated signal transmission can be prevented while specifying an unusable route.

[0056] <Second embodiment>

[0057] The second embodiment will now be described. Note that the system configuration example and the hardware configuration of the device in this embodiment are the same as those in the first embodiment, and therefore their description will be omitted.

[0058] In this embodiment, if communication along a route identified by route identification information becomes unavailable, such as when a radio link failure (RLF) occurs between the wireless link and the forwarding destination device, the relay device determines an alternative forwarding destination device and allows the addition of second route identification information related to an alternative route including the alternative forwarding destination device to the signal. For example, relay device A102 receives a signal including first route identification information corresponding to a first route. If it determines that the received signal cannot be forwarded to relay device B103, it determines relay device C104 as the forwarding destination device and adds second route identification information related to the route including relay device C104 to the header of the received signal. In one example, the second route identification information is information identifying the second or third route mentioned above, including relay device C104. Alternatively, two pieces of second route identification information, one corresponding to the second route and one corresponding to the third route, may be added to the header of the received signal.

[0059] Furthermore, even if a relay device is able to communicate along the route identified by the route identification information, it can add additional route identification information to the received signal. That is, even if a relay device is able to forward a received signal according to the first route identification information contained in the signal, it can still add second route identification information to the received signal and forward the signal with the added information to the forwarding destination device. For example, upon receiving a signal containing route identification information indicating the second route described above, relay device A102 can generate a signal with additional route identification information indicating, for example, a third route added to the received signal and transmit it to relay device C104. In this case, since relay device C104 is included in both the second and third routes, it can select either route and forward the signal to relay device D105 or relay device E106. Furthermore, while a relay device can add route identification information related to routes that pass through its own device, it can also add route identification information related to routes that do not pass through its own device. For example, relay device C104 may forward a signal to which route identification information including the second route of its own device is added, or may forward a signal to which route identification information excluding the first route of its own device is added.

[0060] Furthermore, the device controlling communications for base station apparatus 101 and other devices may pre-notify each relay device of information indicating whether additional identification information is permitted. For example, relay device A 102 may only add the second route identification information described above if it receives a notification from base station apparatus 101 indicating permission for additional identification information. Furthermore, whether route identification information can be added may be determined for each route. For example, base station apparatus 101 may pre-notify each relay device of information specifying route identification information permitted for addition. Furthermore, base station apparatus 101 may pre-notify each relay device of information for determining whether additional information can be added for each of one or more routes. In one example, the information for determining whether additional information can be added may include information on the wireless usage rate for each of one or more routes. In this case, the relay device may determine that additional information is permitted for a route among candidate routes that includes a section where the wireless usage rate exceeds a predetermined value. Furthermore, information on this predetermined value may also be pre-notified from base station apparatus 101 to each relay device. Furthermore, base station 101 may pre-notify each relay device of only the predetermined value. In this case, each relay device compares the radio usage rate of each radio link included in multiple candidate routes between itself and the signal's destination device with the predetermined value. For example, based on whether the radio usage rate for each route is lower than the predetermined value, the relay device may determine whether to add route identification information related to each route. Based on this information, the relay device may determine the route to be added and add the route identification information related to the route.

[0061] Other relay devices that receive the signal with the added route identification information identify the route that includes their own device from among the routes indicated by the two or more route identification information, and then identify the device following their own device in that route to which the signal should be forwarded. The relay device then transmits the signal to the identified device. Furthermore, the relay device may also perform the aforementioned process of adding route identification information in the event of, for example, a RLF in the wireless link between the identified devices.

[0062] When route identification information is added, the relay device may notify the device controlling communications with base station device 101, etc., of the addition of route identification information. Furthermore, the device controlling communications with base station device 101, etc., may be notified of the reason for the addition of route identification information. For example, if the relay device determines that communication along the route identified by the first route identification information included in the received signal is not possible, then, if second route identification information is added, the base station device 101 may not use the route indicated by the first route identification information in the next subsequent signal transmission opportunity. Furthermore, if route identification information is added due to the existence of a route with relatively low wireless usage, the base station device 101 may use the route indicated by the added route identification information in the next subsequent signal transmission opportunity to distribute the load.

[0063] Furthermore, when the second route identification information is added, the relay device may delete the first route identification information included in the received signal. This eliminates the need for other devices receiving the signal forwarded from the relay device to perform forwarding destination determination processing. Furthermore, information indicating whether deletion of the route identification information is permitted may be notified from the base station device 101. In this case, the relay device deletes the first route identification information only when deletion of the route identification information is permitted. Furthermore, the relay device may, for example, pre-acquire from the base station device 101 information used to determine whether route identification information related to one or more routes should be deleted, and determine whether the first route identification information included in the received signal should be deleted. Furthermore, when the first route identification information is deleted, the relay device notifies the base station device 101 of the deletion of the route identification information. This allows the base station device 101 to avoid using the route indicated by the first route identification information in the next and subsequent signal transmission opportunities.

[0064] (Device Configuration)

[0065] Figure 5 1 shows an example of the functional configuration of a relay device according to this embodiment. The relay device may include, for example, a communication unit 501, a route information determination unit 502, a forwarding destination determination unit 503, a forwarding control unit 504, and a route information change unit 505. Furthermore, the relay device may also include a settings acquisition unit 506 and a change notification unit 507. Furthermore, these functional units, such as the processor 201, may be implemented by executing programs stored in the ROM 202.

[0066] In accordance with cellular communication standards, the communication unit 501 is a functional unit for wirelessly communicating with base stations, other relay devices, and terminal devices. The route information determination unit 502 determines the route along which signals received from base stations and other relay devices will be forwarded based on the route identification information contained in the signal. The forwarding destination determination unit 503 determines the device to which the signal should be forwarded based on the route determined by the route information determination unit 502. For example, the forwarding destination determination unit 503 determines the device to which the signal should be forwarded after its own device within the determined route. Furthermore, the forwarding destination determination unit 503 may determine to forward the signal to a device other than the next forwarding destination device determined based on the route identification information, for example, if communication on the wireless link between the forwarding destination devices determined based on the determined route is impossible, or if there is a route with low wireless usage in the wireless link to the destination. The forwarding control unit 504 controls the communication unit 501 to forward the received signal to the forwarding destination device determined by the forwarding destination determination unit 503.

[0067] The route information changing unit 505 adds second route identification information, different from the first route identification information included in the received signal, to the received signal. This addition is performed, for example, in situations where communication over the wireless link between devices at the next forwarding destination determined based on the first route identification information is impossible, or where a route with low wireless usage exists in the wireless link to the destination, so that data can be sent and received via another route. Furthermore, the route information changing unit 505 may arbitrarily add route identification information indicating a usable route. Furthermore, when the route information changing unit 505 adds the second route identification information to the received signal, it deletes the first route identification information from the received signal. For example, when the route determined by the first route identification information is no longer usable, the first route identification information is deleted.

[0068] The setting acquisition unit 506 acquires, for example, setting information indicating whether the addition or deletion of route identification information is permitted, and setting information for determining whether the addition or deletion of route identification information is permitted, from the base station device 101. Furthermore, these settings can be set for each route, or can be set for multiple or all routes collectively. This setting information is notified before the communication of a signal containing data. Based on the setting information acquired by the setting acquisition unit 506, the relay device determines whether the addition / deletion of route identification information is permitted. The route information change unit 505 then executes the addition / deletion of route identification information based on the result of this determination. When the addition / deletion of route identification information is performed, the change notification unit 507 notifies the base station device 101 of the addition / change.

[0069] (Processing Flow)

[0070] use Figure 6 The flow of processing executed by the relay device will be briefly described. Figure 6 The processing is performed, for example, by a relay device that is located in the middle of a route between a relay device directly connected to a terminal device and a base station device (i.e., a relay device that is not located at the end of the route). In this processing, first, the relay device obtains setting information from the base station device 101 (S601). Based on the obtained setting information, the relay device determines whether to allow the addition / deletion of route identification information in subsequent processing. In addition, for example, if the relay device always allows the addition / deletion of route identification information, or if the setting is completed when the relay device is installed, this processing may not be performed.

[0071] A relay device receives a signal from another device (e.g., a base station or another relay device) (S602). The relay device analyzes the received signal, extracts destination information indicating the destination device and route identification information indicating the route contained in the signal, and determines the route along which the signal should be forwarded based on the route identification information (S603). The relay device then determines the destination device to which the signal should be forwarded based on the determined route (S604).

[0072] For example, the relay device determines the device to which the signal should be forwarded after its own device in the route determined in S603 as the forwarding destination device. In this case, for example, if a failure occurs in the wireless link between the next forwarding destination device in the route, the relay device may determine that communication between the forwarding destination devices should not be carried out. In this case, the relay device may determine that other devices not included in the route are the forwarding destinations for the signal. In this case, the relay device, for example, adds route identification information indicating the route including the device determined to be the forwarding destination for the signal (S605). In addition, if there is a route with a low wireless usage rate of the wireless link in the route from its own device to the destination device, the relay device may add the route identification information of the route. In addition, when the route identification information is added, the relay device may delete the route identification information included in the received signal. In addition, if the setting information is obtained in S601, the addition / deletion of route identification information is performed according to the setting information. If there is no route to be added, the addition / deletion of route identification information may not be performed. That is, the route identification information included in the received signal can be maintained as it is. When the relay device adds / deletes route identification information in S605, it notifies the base station device 101 of this fact (S606). Alternatively, this notification may not be performed.

[0073] Thereafter, the relay device transmits the data included in the signal received in S602, the destination information included in the received signal, and the signal including the route identification information set in S605 to the device of the forwarding destination determined in S604 (S607).

[0074] Thus, according to the relay device described above, based on the route identification information included in the signal, when it is difficult to forward the signal along the route, the relay device can continue forwarding the signal to a device capable of forwarding the signal by deviating from the route. Furthermore, in this case, by adding the route identification information indicating the route, as described above, it is possible to facilitate the determination of the forwarding destination of the signal in the forwarding destination device, or to increase the degree of freedom in selecting the forwarding destination in the forwarding device.

[0075] The present invention is not limited to the above-described embodiment, and various modifications and changes can be made within the scope of the gist of the present invention.

[0076] This application claims priority based on Japanese Patent Application No. 2019-147863 filed on August 9, 2019 and Japanese Patent Application No. 2019-147867 filed on August 9, 2019, the entire contents of which are incorporated herein by reference.

Claims

1. A relay device that relays a signal from a base station device or a terminal device to a destination device, wherein: The relay device comprises: a receiving unit configured to receive the signal; and A decision unit configured to decide, based on destination information indicating the destination device included in the received signal and based on route information stored in the relay device, a device to which the relay device has established a connection as a next-hop device to which the signal will be forwarded, when the relay device does not maintain route identification information included in the received signal and indicating a route through which the data included in the received signal will be forwarded, and thus a next-hop device to which the signal will be forwarded cannot be identified based on the route identification information.

2. The relay device according to claim 1, wherein: When the relay device maintains route identification information included in the received signal, indicating a route through which data included in the received signal will be forwarded, and the next hop to which the signal will be forwarded can be identified based on the route identification information, the decision unit decides, based on the route identification information, a device to which the relay device has established a connection as the next hop device to which the signal will be forwarded.

3. The relay device according to claim 1, wherein: The decision unit decides the next hop device to which the signal is to be forwarded regardless of an instruction from the base station device.

4. The relay device according to claim 1, wherein: The determination unit determines the next hop device to which the signal is to be forwarded according to an instruction from the base station device.

5. The relay device according to claim 1, wherein: A plurality of next hop candidate devices are set in the relay device, The decision unit decides one of the plurality of next hop candidate devices as the next hop device to which the signal is to be forwarded based on the destination information and based on the route information.

6. The relay device according to claim 5, wherein: The relay device has established a connection with each of the multiple next-hop candidate devices.

7. The relay device according to claim 1, wherein: The decision unit does not decide a device having a link with the relay device on which a radio link failure (RLF) has occurred as the next-hop device to which the information is to be forwarded.

8. The relay device according to claim 1, wherein: The route identification information included in the received signal includes: information for identifying devices included in the communication route from the base station device or the terminal device to the destination device, and information indicating the order between the devices, and the signal will be forwarded in the order.

9. The relay device according to claim 1, wherein: The relay device further includes a sending unit configured to send the signal to the next hop device to which the signal is to be forwarded, as determined by the determining unit. The transmitted signal includes route identification information different from route identification information included in the received signal.

10. The relay device according to claim 1, wherein: The relay device further includes a sending unit configured to send the signal to the next hop device to which the signal is to be forwarded, as determined by the determining unit. The transmitted signal includes the same route identification information as the route identification information included in the received signal.

11. The relay device according to claim 1, wherein: The relay device further includes a sending unit configured to send the signal to the next hop device to which the signal is to be forwarded, as determined by the determining unit. The signal sent does not include route identification information.

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