Wireless communication device, communication method, control circuit, and storage medium

Abstract

A wireless communication device (1) for transmitting data on the basis of a routing table is provided with a transmission processing unit (31) that determines which of unicast transmission and broadcast transmission is to be executed on the basis of the presence or absence of the routing table and the registration status of the destination of data to be transmitted on the routing table, and transmits the data to be transmitted by a transmission method corresponding to a determination result.

Description

Wireless communication device, communication method, control circuit, and storage medium

[0001] The present disclosure relates to a wireless communication device, a communication method, a control circuit, and a storage medium that constitute a mobile communication system.

[0002] As a new function of mobile communication systems, side link (SL) communication, which allows terminals to communicate directly with each other without going through a base station, has been standardized by 3GPP (registered trademark). Hereinafter, side link communication will be referred to as terminal-to-terminal communication.

[0003] In mobile communication systems, relay transmission using terminal-to-terminal communication has attracted attention mainly for the purpose of extending the coverage of base stations. In relay transmission using terminal-to-terminal communication, route selection, which determines which relay station to use to form a transmission path, is important.

[0004] In a route selection method for relay transmission using end-to-end communication, a Direct Communication Request message is transmitted and received to form a unicast link between a transmitting station, a receiving station, and a relay station. That is, the transmitting station broadcasts a Direct Communication Request message, and each relay station that receives the message broadcasts the same message again. The receiving station selects a relay route based on the received message (see, for example, Non-Patent Document 1).

[0005] Another route selection method is the Optimized Link State Routing (OLSR) protocol, which is an ad-hoc route construction method (see Non-Patent Document 2). In this method, topology information of the entire network is shared by periodically mutually transmitting Hello messages and Topology Control (TC) messages, and a route table (or routing table) is created in each node that forms the network.

[0006] In the above-described route selection method, if a communication failure occurs on a route during relay transmission, it is possible to change the relay station performing the relay transmission and transmit data, but there is a problem in that it takes time to determine that the route has become unusable. To address this problem, Patent Document 1 describes a technology that detects a detour route when a communication failure occurs on a route registered in a routing table, and uses the detour route to communicate with the target node.

[0007] JP 2016-96408 A

[0008] 3GPP TR 23.752 V17.0.0IETF RFC3626

[0009] The technology described in Patent Literature 1 enables relay transmission using a detour route even when a communication failure occurs on a route registered in a routing table. However, it cannot address the following issues: for example, when relay transmission is performed with a newly joining node as the destination, if route information to the destination node is not registered in the routing table, the destination becomes unknown and the packet is discarded; and if the routing table itself does not exist because the routing table is being created or the information for creating the routing table is not held due to the failure of a control message to be delivered, the destination becomes unknown and the packet is discarded.

[0010] The present disclosure has been made in view of the above, and aims to provide a wireless communication device that can prevent packets from being discarded in transmission processing based on a routing table.

[0011] In order to solve the above-mentioned problems and achieve the objectives, the present disclosure is characterized by a wireless communication device that transmits data based on a routing table, and is equipped with a transmission processing unit that determines whether to perform unicast transmission or broadcast transmission based on the presence or absence of a routing table and the registration status of the destination of the data to be transmitted in the routing table, and transmits the data to be transmitted using a transmission method in accordance with the determined result.

[0012] The present disclosure advantageously provides a wireless communication device that can prevent packets from being discarded in a transmission process based on a routing table.

[0013] FIG. 1 is a diagram illustrating an example of a route of relay transmission executed in a communication system configured by a wireless communication device according to a first embodiment; FIG. 2 is a diagram for explaining a construction operation of a routing table; FIG. 3 is a diagram illustrating an example of a functional block configuration of a wireless communication device according to a first embodiment;

[0014] Hereinafter, a wireless communication device, a communication method, a control circuit, and a storage medium according to embodiments of the present disclosure will be described in detail with reference to the accompanying drawings.

[0015] First Embodiment Fig. 1 is a diagram illustrating an example of a route of relay transmission executed in a communication system configured by a wireless communication device according to a first embodiment.

[0016] The communication system shown in Fig. 1 includes a transmitting station 100 that is a source of relay transmission data, a receiving station 101 that is a destination of the relay transmission data, and relay stations 102 to 106 that relay the data. A wireless communication device according to this embodiment operates as the transmitting station 100, the receiving station 101, or the relay stations 102 to 106 shown in Fig. 1.

[0017] In the example shown in FIG. 1, four data transmission paths 107 to 110 have already been established as paths for transmitting data from the transmitting station 100 to the receiving station 101. That is, information on the data transfer destinations when transmitting data via each of the data transmission paths 107 to 110 has been registered in the routing tables of the transmitting station 100, the receiving station 101, and the relay stations 102 to 106.

[0018] Although FIG. 1 shows five relay stations, the number of relay stations is not limited to this. The arrangement of transmitting station 100, receiving station 101, and relay stations 102 to 106 is also an example. In this embodiment, all wireless communication devices can function as transmitting stations, receiving stations, and relay stations. That is, a wireless communication device can operate as a transmitting station for relay transmission, a receiving station for relay transmission, or a relay station for relay transmission.

[0019] Next, a procedure for constructing a routing table by wireless communication devices operating as the transmitting station 100, receiving station 101, and relay stations 102 to 106 in the configuration of Figure 1 will be briefly described. Note that in the procedure described below, nodes correspond to wireless communication devices. Furthermore, the construction of the routing table is performed in accordance with a known routing protocol. In this embodiment, as an example, a procedure for constructing a routing table in accordance with the OLSR protocol described in Non-Patent Document 2 above will be described, but the method for constructing the routing table is not limited thereto. Any method may be used to construct and update the routing table.

[0020] (Step 1) Each wireless communication device (transmitting station 100, receiving station 101, relay stations 102 to 106) broadcasts a Hello message. The Hello message contains information about the neighboring nodes of the node transmitting the Hello message and link information between the neighboring nodes. The Hello message is a message for exchanging information about the connection relationships between wireless communication devices. Each wireless communication device periodically transmits a Hello message.

[0021] (Step 2) Each wireless communication device builds a local link set from the information contained in the received Hello messages. The local link set here is a collection of information contained in each Hello message received from other wireless communication devices.

[0022] (Step 3) If a second adjacent node exists from the node's perspective as a result of the exchange of Hello messages, an MPR (Multi Point Relay) is selected from among the node's adjacent nodes. The relationship between adjacent nodes and second adjacent nodes is shown in FIG. 2. FIG. 2 is a diagram for explaining the operation of building a routing table. In the example shown in FIG. 2, node 200 and node 201 are adjacent to each other and are connected by edge 203. Node 201 and node 202 are adjacent to each other and are connected by edge 204. When nodes 200, 201, and 202 exchange Hello messages, node 202 exists beyond node 201 from the node 200's perspective, so node 200 selects node 201 as the MPR. The MPR selection result, i.e., information indicating that node 200 has selected node 201 as the MPR, is subsequently notified to the adjacent node (node ​​201) by a Hello message transmitted by node 200.

[0023] (Step 4) The wireless communication device selected as an MPR broadcasts a TC message. The TC message includes information about the node (called an MPR selector) that selected the node sending the TC message as an MPR. In the example shown in FIG. 2, node 201 transmits a TC message that includes information about node 200, which is an MPR selector. If node 201 is also selected as an MPR for node 202, node 201 transmits a TC message that includes information indicating that node 200 and node 202 are MPR selectors. When a wireless communication device selected as an MPR receives a TC message from another wireless communication device, it broadcasts, i.e., forwards, the received TC message. Wireless communication devices that are not selected as an MPR discard the TC message without forwarding it, even if they receive it.

[0024] (Step 5) The wireless communication device that received the TC message creates a topology set from the information contained in the TC message. The topology set here is a collection of information contained in the received TC message. The topology set and the local link set described above represent the topology of the network.

[0025] (Step 6) Each wireless communication device creates a routing table for all wireless communication devices as destinations based on the local link set and topology set it holds. That is, each wireless communication device creates route information for each of the cases where all wireless communication devices are destinations and registers it in the routing table. If route information has already been registered in the routing table, it updates the route information. The routing table is updated when the information constituting the local link set is updated and when the topology set is updated.

[0026] FIG. 3 is a diagram illustrating an example of a functional block configuration of the wireless communication device 1 according to the first embodiment.

[0027] 3 , the wireless communication device 1 includes a transmission processing unit 31 that is configured with a TC message transmitting unit 12, a Hello message transmitting unit 13, a broadcast transmitting unit 14, a unicast transmitting unit 15, a first transmission determining unit 19, and a second transmission determining unit 20. The wireless communication device 1 also includes a reception processing unit 32 that is configured with a reception determining unit 11, a Hello message receiving unit 16, a TC message receiving unit 17, a local link set acquiring unit 21, a topology set acquiring unit 22, and a user data receiving unit 25. The wireless communication device 1 also includes a transmission request unit 18, a routing table holding unit 23, and a route calculation unit 24.

[0028] The TC message transmitting unit 12 periodically transmits a TC message when the wireless communication device 1 is selected as an MPR. The Hello message transmitting unit 13 periodically transmits a Hello message.

[0029] The broadcast transmitter 14 broadcasts the user data packet when the user data packet is input from the first transmission determination unit 19 or the second transmission determination unit 20. The detailed operation of the broadcast transmitter 14 will be described later.

[0030] When the user data packet is input from the second transmission determining unit 20, the unicast transmitting unit 15 unicasts the user data packet.

[0031] The Hello message receiving unit 16 receives Hello messages transmitted from other wireless communication devices. The TC message receiving unit 17 receives TC messages transmitted from other wireless communication devices. The local link set acquiring unit 21 acquires information contained in the Hello messages received by the Hello message receiving unit 16 and creates a local link set. The topology set acquiring unit 22 acquires information contained in the TC messages received by the TC message receiving unit 17 and creates a topology set.

[0032] The route calculation unit 24 calculates a relay route, which is a route for relay transmission, for each user data packet addressed to each of the other wireless communication devices, based on the local link set created by the local link set acquisition unit 21 and the topology set created by the topology set acquisition unit 22. The routing table holding unit 23 holds a routing table in which information on the relay routes calculated by the route calculation unit 24 is registered.

[0033] The transmission request unit 18 generates a transmission request for transmitting the user data input from the reception determination unit 11 to another wireless communication device. The transmission request includes the user data to be transmitted to the other wireless communication device and destination information for the user data (hereinafter, may be referred to as a destination address). The destination information included in the transmission request is information indicating the final destination of the user data, which corresponds to the address of the receiving station 101 in the example shown in FIG. 1. Other information may also be included in the transmission request. The transmission request unit 18 also generates a transmission request when user data addressed to another wireless communication device is generated within the transmission request unit 18. The transmission request unit 18 outputs the generated transmission request to the first transmission determination unit 19.

[0034] When a transmission request is input from the transmission request unit 18, the first transmission determination unit 19 checks whether a routing table exists in the routing table holding unit 23, and if a routing table exists, outputs the transmission request to the second transmission determination unit 20. If a routing table does not exist in the routing table holding unit 23, the first transmission determination unit 19 outputs the transmission request to the broadcast transmission unit 14. The detailed operation of the first transmission determination unit 19 will be described later.

[0035] When a transmission request is input from the first transmission determination unit 19, the second transmission determination unit 20 checks whether a destination corresponding to the destination information included in the transmission request exists in the routing table held by the routing table holding unit 23. If a corresponding address does not exist in the routing table, the second transmission determination unit 20 outputs the transmission request to the broadcast transmission unit 14, and if a corresponding address exists in the routing table, the second transmission determination unit 20 outputs the transmission request to the unicast transmission unit 15. The detailed operation of the second transmission determination unit 20 will be described later.

[0036] The reception determination unit 11 performs reception determination for user data transmitted from other wireless communication devices, i.e., determines whether the user data is addressed to the device itself. The reception determination unit 11 also performs duplicate reception determination, i.e., determines whether user data identical to previously received user data has been received twice. The reception determination unit 11 outputs user data that is not a duplicate reception and is addressed to the device itself to the user data receiving unit 25, and outputs user data that is not addressed to the device itself to the transmission request unit 18. The detailed operation of the reception determination unit 11 will be described later. The user data receiving unit 25 performs reception processing for the user data input from the reception determination unit 11.

[0037] 4 is a flowchart showing an example of the operation of the first transmission determination unit 19 of the wireless communication device 1 according to the first embodiment. The detailed operation of the first transmission determination unit 19 will be described.

[0038] 4, when a transmission request is input (step S11), the first transmission determination unit 19 checks whether a routing table exists (step S12). If a routing table exists, i.e., if the routing table holding unit 23 holds a routing table (step S12: Yes), the first transmission determination unit 19 outputs a transmission request to the second transmission determination unit 20 (step S13).

[0039] If there is no routing table (step S12: No), the first transmission determination unit 19 sets a destination address in the packet header of the user data according to the destination information included in the transmission request, and further sets a wildcard in the address specifying the next forwarding destination (hereinafter referred to as the next address) (step S14). The wildcard does not correspond to an address specific to a device and does not correspond to any device. The wildcard is information indicating that the forwarding destination is not limited to a single device. The first transmission determination unit 19 also sets a broadcast flag (step S15) and outputs the user data packet to the broadcast transmission unit 14 (step S16). The broadcast flag uses, for example, a bit in an unused area in the packet header.

[0040] In this way, by switching the transmission method to broadcast depending on whether or not a routing table exists, transmission to any destination is possible even if a routing table does not exist.

[0041] 5 is a flowchart showing an example of the operation of the second transmission determination unit 20 of the wireless communication device 1 according to the first embodiment. The detailed operation of the second transmission determination unit 20 will be described.

[0042] 5, when a transmission request is input (step S21), the second transmission determination unit 20 acquires a destination address from the transmission request (step S22). The second transmission determination unit 20 then refers to the routing table held by the routing table holding unit 23 (step S23) and checks whether the destination address exists in the routing table (step S24).

[0043] If the destination address exists in the routing table (step S24: Yes), the second transmission determination unit 20 sets the destination address acquired in step S22 in the packet header of the user data, i.e., sets the destination address acquired in step S22 as the destination of the user data, and sets the next address according to the routing table (step S25).The second transmission determination unit 20 outputs the user data packet with the destination and next address set to the unicast transmission unit 15 (step S26).

[0044] If the destination address does not exist in the routing table (step S24: No), the second transmission determination unit 20 sets the destination address acquired in step S22 in the packet header of the user data and sets a wildcard in the next address (step S27).The second transmission determination unit 20 also sets the broadcast flag (step S28) and outputs the user data packet to the broadcast transmission unit 14 (step S29).

[0045] In this way, by switching the transmission method to broadcast depending on whether or not a route to the destination exists in the routing table, transmission to any destination becomes possible even if a routing table does not exist.

[0046] 6 is a flowchart showing an example of the operation of the reception determination unit 11 of the wireless communication device 1 according to the first embodiment. The detailed operation of the reception determination unit 11 will be described.

[0047] 6, when the reception determination unit 11 receives user data (step S31), it checks whether the user data is broadcasted (step S32). As will be described later, a broadcast signal is inserted in a broadcast packet as information indicating that the data has been broadcasted. Therefore, the reception determination unit 11 makes a determination based on the presence or absence of a broadcast signal.

[0048] If the received user data is broadcasted (step S32: Yes), the reception determination unit 11 checks whether it is a duplicate packet (step S33). In the case of broadcasted user data, step S33 is executed because there is a possibility that multiple identical packets will be received in duplicate if a broadcast process is performed at a relay station on a multi-hop route. If the received user data is a duplicate packet (step S33: Yes), the reception determination unit 11 discards the user data (step S37). If the received user data is not broadcasted user data (step S32: No), the reception determination unit 11 proceeds to step S34.

[0049] If the received user data does not correspond to a duplicate packet (step S33: No), the reception determination unit 11 checks whether the destination is the wireless communication device itself (step S34). If the destination is the wireless communication device itself (step S34: Yes), the reception determination unit 11 determines to execute reception processing of the user data (step S39). In this case, the reception determination unit 11 outputs the user data to the user data receiving unit 25. If the destination is not the wireless communication device itself (step S34: No), the reception determination unit 11 checks whether the wireless communication device itself has been selected as the MPR of another wireless communication device (step S35). If the wireless communication device itself has not been selected as the MPR of another wireless communication device (step S35: No), the reception determination unit 11 discards the user data (step S37). If the wireless communication device itself has been selected as the MPR of another wireless communication device (step S35: Yes), the reception determination unit 11 checks whether the next address of the user data is its own address, i.e., whether the address of the wireless communication device itself is set as the next address of the user data (step S36). If the next address of the user data is not its own address (step S36: No), the reception determination unit 11 discards the user data (step S37). If the next address of the user data is its own address (step S36: Yes), the reception determination unit 11 decides to execute a transfer process for the user data (step S38). In this case, the reception determination unit 11 outputs the user data to the transmission request unit 18.

[0050] In this way, by having the reception determination unit 11 perform the reception determination process according to the flowchart in Fig. 6, it is possible to prevent network congestion caused by unnecessary duplicate packet transmissions. As a secondary effect, by using the reception determination process in each wireless communication device to sort received data into three ways - packet discard, forwarding, and reception - it is possible to reduce the frequency of unnecessary data transmission and achieve a reduction in power consumption.

[0051] 7 is a flowchart showing an example of the operation of the broadcast transmitter 14 of the wireless communication device 1 according to the first embodiment. The detailed operation of the broadcast transmitter 14 will be described.

[0052] 7, when user data is input to the broadcast transmitter 14 (step S41), the broadcast transmitter 14 clears the broadcast flag (step S42). The broadcast transmitter 14 then inserts a broadcast signal indicating that the user data packet has been transmitted by broadcast into the header of the user data packet (step S43), and transmits the user data (step S44). By inserting the broadcast signal into the header, other wireless communication devices that receive the user data packet can easily determine whether or not they have received a broadcast packet.

[0053] As described above, the wireless communication device 1 according to the present embodiment switches the transmission method between unicast and broadcast based on whether a routing table exists and whether an address is registered in the routing table. That is, if there is no routing table and if the next address, which is the forwarding address corresponding to the destination of the user data, is not registered in the routing table, the wireless communication device 1 performs broadcast transmission to transfer the user data. If the next address corresponding to the destination of the user data is registered in the routing table, the wireless communication device 1 performs unicast transmission to transfer the user data. This is expected to have the effect of enabling packets to be delivered to any destination even if there is no routing table or if the next address corresponding to the user data is not in the routing table.

[0054] Second Embodiment Fig. 8 is a diagram showing an example of a functional block configuration of a wireless communication device 1a according to a second embodiment. In the wireless communication device 1a, the reception processing unit 32 of the wireless communication device 1 described in the first embodiment is replaced with a reception processing unit 32a. The reception processing unit 32a has a configuration in which the local link set acquisition unit 21 of the reception processing unit 32 is replaced with a local link set acquisition unit 21a. Since the functional blocks of the wireless communication device 1a other than the local link set acquisition unit 21a are the same as those of the wireless communication device 1, the same reference numerals are used and their description will be omitted.

[0055] The local link set acquisition unit 21a generates a local link set after adding hysteresis to the Hello message received by the Hello message receiving unit 16.

[0056] FIG. 9 is a flowchart illustrating an example of an operation of the wireless communication device 1a according to the second embodiment to generate a local link set.

[0057] In the operation of generating a local link set in the wireless communication device 1a, first, the Hello message receiver 16 receives a Hello message (step S51). Next, the local link set acquisition unit 21a counts the number of times a Hello message with the same content has been received (step S52). Note that the counting of the number of times the message has been received may be performed by the Hello message receiver 16. Next, the local link set acquisition unit 21a checks whether target node information exists in the local link set, that is, whether information included in a Hello message previously received from the same party as the Hello message received in step S51 has already been registered in the local link set (step S53).

[0058] If the target node information does not exist in the local link set (step S53: No), the local link set acquisition unit 21a updates the local link set (step S55). In step S55, the local link set acquisition unit 21a registers the information included in the Hello message received in step S51 as new information in the local link set. Furthermore, if the target node information exists in the local link set (step S53: Yes), the local link set acquisition unit 21a checks whether the number of times a Hello message with the same content has been received reaches a specified number (e.g., N times) (step S54). If the number of times a Hello message with the same content has been received is less than the specified number (step S54: No), the process returns to step S51. If the number of times a Hello message with the same content has been received reaches the specified number (step S54: Yes), the local link set acquisition unit 21a updates the local link set based on the information included in the Hello message received in step S51 (step S55). At this time, the local link set acquisition unit 21a also resets the number of times a Hello message with the same content has been received.

[0059] As described above, in the wireless communication device 1a according to this embodiment, the local link set acquisition unit 21a counts the number of times that Hello messages from the same sender are received, and when the number of times reaches a predetermined number, updates the information registered in the local link set. In this way, by introducing hysteresis into the update of the local link set based on the information contained in the Hello message, it becomes possible to select a more stable relay station for communication, and stable communication can be expected.

[0060] Next, the hardware configuration of the wireless communication devices 1 and 1a described in each embodiment will be described. Since the wireless communication devices 1 and 1a are realized by similar hardware, an example of the hardware configuration of the wireless communication device 1 will be described here.

[0061] The transmission processing unit 31, reception processing unit 32, routing table holding unit 23, route calculation unit 24, and transmission request unit 18 of the wireless communication device 1 are realized by processing circuits that are dedicated hardware, specifically, single circuits, composite circuits, programmed processors, parallel programmed processors, ASICs (Application Specific Integrated Circuits), FPGAs (Field Programmable Gate Arrays), or processing circuits that combine these.

[0062] Furthermore, some or all of the components of the wireless communication device 1, i.e., the transmission processing unit 31, the reception processing unit 32, the routing table holding unit 23, the route calculation unit 24, and the transmission request unit 18, may be realized by a processing circuit including a processor 91, a memory 92, a transmission circuit 93, and a reception circuit 94 shown in FIG. 10 . FIG. 10 is a diagram showing an example of a processing circuit that realizes some or all of the components of the wireless communication device 1. The processor 91 is a CPU (Central Processing Unit, also referred to as a central processing unit, processing unit, arithmetic unit, microprocessor, microcomputer, processor, or DSP (Digital Signal Processor)). The memory 92 is, for example, a RAM (Random Access Memory), a ROM (Read Only Memory), a flash memory, an EPROM (Erasable Programmable Read Only Memory), or an EEPROM (registered trademark). The transmission circuit 93 is an electronic circuit that performs transmission processing of wireless signals, and the reception circuit 94 is an electronic circuit that performs reception processing of wireless signals.

[0063] When some or all of the components of the wireless communication device 1 are realized by the processor 91, memory 92, transmission circuit 93, and reception circuit 94 shown in FIG. 10 , a program for operating as some or all of the transmission processing unit 31, reception processing unit 32, routing table holding unit 23, route calculation unit 24, and transmission request unit 18 of the wireless communication device 1 is stored in the memory 92. The processor 91 reads and executes this program to realize some or all of the transmission processing unit 31, reception processing unit 32, routing table holding unit 23, route calculation unit 24, and transmission request unit 18 of the wireless communication device 1. Note that when some of the components of the wireless communication device 1 are realized by the processor 91, memory 92, transmission circuit 93, and reception circuit 94, the remaining components are realized by the single circuit, composite circuit, or the like described above. In other words, the wireless communication device 1 may have some components realized by dedicated hardware, and the remaining components realized by the processor 91, memory 92, transmission circuit 93, and reception circuit 94 shown in FIG. 10 .

[0064] When some or all of the components of the wireless communication device 1 are realized by a processor 91, a memory 92, a transmitting circuit 93, and a receiving circuit 94, the above-mentioned program stored in the memory 92 may be provided to a user, for example, in a form written on a storage medium such as a CD (Compact Disc)-ROM or a DVD (Digital Versatile Disc)-ROM, or may be provided via a network.

[0065] The configurations shown in the above embodiments are merely examples, and may be combined with other known technologies, or different embodiments may be combined with each other. It is also possible to omit or modify parts of the configurations as long as they do not deviate from the gist of the invention.

[0066] 1, 1a wireless communication device, 11 reception determination unit, 12 TC message transmission unit, 13 Hello message transmission unit, 14 broadcast transmission unit, 15 unicast transmission unit, 16 Hello message reception unit, 17 TC message reception unit, 18 transmission request unit, 19 first transmission determination unit, 20 second transmission determination unit, 21, 21a local link set acquisition unit, 22 topology set acquisition unit, 23 routing table holding unit, 24 route calculation unit, 25 user data reception unit, 31 transmission processing unit, 32, 32a reception processing unit, 100 transmitting station, 101 receiving station, 102 to 106 relay stations, 107 to 110 data transmission paths, 200 to 202 nodes, 203, 204 edges.

Claims

1. A wireless communication device that transmits data based on a routing table, comprising: a transmission processing unit that determines whether to perform unicast transmission or broadcast transmission based on the presence or absence of the routing table and the registration status of the destination of the data to be transmitted in the routing table, and transmits the data to be transmitted using a transmission method in accordance with the determined result.

2. The wireless communication device described in claim 1, characterized in that the transmission processing unit comprises: a first transmission determination unit that decides to broadcast the data to be transmitted if the routing table does not exist; and a second transmission determination unit that decides to unicast the data to be transmitted if the routing table exists and the destination of the data is registered in the routing table, and that decides to broadcast the data to be transmitted if the routing table exists and the destination of the data is not registered in the routing table.

3. The wireless communication device according to claim 2, characterized in that the transmission processing unit is provided with a broadcast transmission unit that inserts a broadcast signal indicating that the data is broadcast into the data to be transmitted and broadcasts the data.

4. The wireless communication device according to claim 2 or 3, characterized in that the first transmission determination unit and the second transmission determination unit set a wildcard as an address indicating the next destination for the data to be transmitted that has been decided to be broadcast transmitted.

5. A wireless communication device as described in any one of claims 1 to 4, characterized in that it receives a message for exchanging information regarding the connection relationship between wireless communication devices from another wireless communication device, and updates the routing table when it receives the message with the same content a predetermined number of times.

6. A wireless communication device according to any one of claims 1 to 5, further comprising a reception determination unit which, when the same broadcast data is received multiple times, determines to discard the duplicated data.

7. The wireless communication device according to claim 6, characterized in that, when data transmitted by unicast is received, the reception determination unit decides to forward the received data if the wireless communication device itself is selected as a multipoint relay and the address of the wireless communication device itself is set as the address specifying the forwarding destination.

8. A communication method executed by a wireless communication device that transmits data based on a routing table, comprising: a first step of determining whether to perform unicast transmission or broadcast transmission based on the presence or absence of the routing table and the registration status of the destination of the data to be transmitted in the routing table; and a second step of transmitting the data using a transmission method in accordance with the result of the determination in the first step.

9. A control circuit for controlling a wireless communication device that transmits data based on a routing table, comprising: a first step of determining whether to perform unicast transmission or broadcast transmission based on the presence or absence of the routing table and the registration status of the destination of the data to be transmitted in the routing table; and a second step of transmitting the data using a transmission method in accordance with the result of the determination in the first step.

10. A storage medium storing a program for controlling a wireless communication device that transmits data based on a routing table, the program causing the wireless communication device to execute the following steps: a first step of determining whether to perform unicast transmission or broadcast transmission based on the presence or absence of the routing table and the registration status of the destination of the data to be transmitted in the routing table; and a second step of transmitting the data using a transmission method in accordance with the result of the determination in the first step.

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