Radio communication system and radio communication terminal

Description: TECHNICAL FIELD [Detailed description of the invention]

【0001】

[Technical field to which the invention belongs]

The present invention relates to a wireless communication system, a wireless communication terminal, and a wireless communication packet that perform multi-hop communication.

【0002】

[Conventional technology]

In communication between a certain wireless communication terminal and another wireless communication terminal, a communication mode in which one or more other wireless communication terminals intervene as a relay station is called multi-hop communication. This wireless communication terminal can create information and transmit the information, and can also function as a relay station.

【0003】

An ad hoc network is a network that mediates communication between first and second wireless communication terminals (hereinafter, abbreviated as "terminals"). Communication between the first terminal and the relay terminal, communication between the relay terminals, or communication between the relay terminal and the second terminal is also a part of communication in the ad hoc network. As a form of ad hoc network, the IBSS (Independent Basic Service Set) specified in the IEEE 802.11 wireless LAN system (ISO / IEC 8802-11: 1999 (E) ANSI / IEEE Std 802.11, 1999 edition) is known. ..

【0004】

The configuration of the IEEE 802.11 wireless LAN system that communicates between terminals will be described with reference to Fig. 1. The configuration of the wireless LAN system shown in Fig. 1 is IBSS in the IEEE 802.11 wireless LAN. In this IBSS, the minimum system configuration is when at least two terminals (for example, terminal 901 and terminal 902) communicate with each other.

【0005】

In an ad hoc network where multiple terminals exist in the system and communicate between terminals, when transmitting information such as data to terminals far away, the communication power is increased to directly communicate with the other terminal. In some cases, a nearby terminal is used as a relay station, and data is transmitted to the destination terminal by transmitting information via the relay station. The latter communication mode corresponds to multi-hop communication (see, for example, Patent Document 1).

【0006】

Generally, when a terminal functions as a relay station and multi-hop communication is performed within IBSS via this terminal, four addresses are required. That is, the address of the direct destination relay station of the current data packet, the address of the direct source relay station of the current data packet, the address of the terminal that is the final destination, and the address of the source terminal that generated and transmitted the information are required. Become.

【0007】

[Patent Document 1]

U.S. Pat. No. 6,046,978 [0008]

[Problems to be Solved by the Invention]

However, in the conventional IBSS as shown in FIG. 1, only three address fields are used, and it is impossible to specify the above four addresses.

【0009】

Therefore, in the conventional wireless terminal device, the address control related to the multi-hop communication in IBSS cannot be supported at the media access control layer (MAC layer) level, and the control must be entrusted to a special higher level. There is a problem.

【0010】

The present invention has been made in consideration of such circumstances, and an object of the present invention is to additionally add an address control function for relay transmission of wireless communication data packets, and to perform a MAC layer without changing an existing basic configuration. The purpose is to easily realize multi-hop communication at the level.

【0011】

[Means for solving problems]

The present invention is configured as follows in order to solve the above problems and achieve the object. In the wireless communication system of the present invention, when a wireless communication packet is transmitted from a first wireless communication terminal to a second wireless communication terminal, the transmission of the wireless communication packet is relayed by at least one other wireless communication terminal. In the communication system, the header portion of the wireless communication packet has a first field representing the address of the second wireless communication terminal which is the final destination and a first field representing the address of the first wireless communication terminal which is the source. The first wireless communication terminal has at least three address fields including a second field and a third field representing the address of the other wireless communication terminal that is a direct destination of the wireless communication packet. Is characterized in that the address of the other wireless communication terminal is set in the third field, and the other wireless communication terminal executes a relay process with reference to the third field.

【0012】

Further, the wireless communication terminal of the present invention is a wireless communication terminal capable of relaying transmission of a wireless communication packet between other wireless communication terminals, and the header portion of the wireless communication packet is the address of the wireless communication terminal which is the final destination. A first field representing, a second field representing the address of the wireless communication terminal that is the source, and a third field that represents the address of any of the wireless communication terminals that are the direct destinations of the wireless communication packet. It has at least three address fields including the above, and includes a processing means for relay processing the radio communication packet with reference to the third field.

【0013】

According to the above configuration, an address control function for relay transmission of wireless communication packets is additionally provided, and multi-hop communication at the MAC layer level can be easily realized without changing the existing basic configuration. That is, it becomes possible to handle address control related to multi-hop communication at the MAC layer level, and it is not necessary to entrust address control to a higher level.

【0014】

Multi-hop communication is realized by adding the relay function used by the terminal base station in the inter-terminal communication. Implementation at the MAC layer is easy, and it is effective for prompt response to make terminals perform multi-hop communication.

【0015】

By adding additional functions to the basic functions of inter-terminal communication in this way, communication between these terminals is not hindered even in a system in which terminals that do not correspond to the present invention coexist. Further, when multi-hop communication is performed between the terminals according to the present invention in the mixed system, the transmission output in the multi-hop communication can be suppressed, and the interference in the entire system can be reduced.

【0016】

Further, in the present invention, the third field is extracted, and based on the third field, it is determined whether or not the direct destination of the wireless communication packet is the own terminal, and the case is the own terminal. Updates the third field and then transmits the radio communication packet to yet another radio communication terminal.

【0017】

Therefore, the terminal that receives the data packet transmitted by the terminal that intends to perform multi-hop communication can determine whether or not the terminal itself is the final destination terminal by referring to the MAC header section. When the terminal itself is not the final destination terminal, the terminal can realize relay transmission of the wireless communication data packet, that is, multi-hop communication by transferring the received data packet to another terminal.

【0018】

Further, in the present invention, the header portion of the wireless communication packet further has a fourth field representing the address of the wireless communication terminal that is the direct source of the wireless communication packet. In this way, by describing TA in the address field of address 3 of the MAC header part of the data packet transmitted using the form of multi-hop communication, the data packet receives the result of the relay station executing the routing selection process. It is possible to feed back to the previous terminal, and further to the transmitting terminal before that, and the routing table can be updated in response to the movement of the terminal and the change in the radio propagation environment.

【0019】

Furthermore, in the present invention, the address represented by the first field or the third field includes a group address. Therefore, by configuring the group address to be specified when performing multi-hop communication, the packet can be transmitted to the terminal which is the final destination via a plurality of relay terminals. Further, the packet can be transmitted even when there are a plurality of terminals that are the final destinations.

【0020】

Select another wireless communication terminal for relay from the routing table. In the routing table, the address (DA) of the relay station which is the final destination, the address (RA) of the relay station which is the direct destination of the current data packet corresponding to the DA, and the communicable station are written. In addition to the communicable station, the reception level of the beacon signal from the communicable station is also written. A routing table is constructed that describes the relay stations of the other party with which each relay station can directly communicate with IBSS.

【0021】

Each relay station having the routing table generated and updated as described above should transmit next when generating a data packet related to multi-hop communication for transmission or when relaying the data packet. The relay station can be selected appropriately.

【0022】

Furthermore, in the present invention, the routing table includes information indicating the reliability between the wireless communication terminals related to the relay. By using such a routing table, it is possible to realize multi-hop communication in consideration of the reliability of the communication route at the time of relaying.

【0023】

Further, the present invention updates the routing table by exchanging packets between wireless communication terminals. By notifying other relay stations capable of direct communication of the routing table owned by each relay station in this way, each relay station increases the information of the other relay station and updates the routing table. Each relay station with an updated routing table appropriately selects the relay station to be transmitted next when generating a data packet related to multi-hop communication for transmission or when relaying the data packet. Can be done.

【0024】

Further, the present invention updates the routing table based on the reception level of the signal received by the wireless communication terminal. As a result, when the relay stations receive the data packets related to the multi-hop communication, these relay stations can be candidates for the relay station to transmit the data packets next.

【0025】

Furthermore, in the present invention, the routing table includes information indicating the number of wireless communication terminals related to the relay. In order to select a communication route with a smaller number of relay stations, the direct partner terminal to be transmitted next can be selected.

【0026】

Furthermore, the present invention cancels the relay according to the information on the number of wireless communication terminals related to the relay included in the routing table. In the system as a whole, when the routing from the terminal that is the source to the terminal that is the final destination is not established, the transmitted data packet takes multiple communication routes, and the data packet is repeatedly relayed, so that the data packet is generated. It will be possible to prevent divergence in the system.

【0027】

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, the wireless communication system and the wireless communication terminal according to the embodiment of the present invention will be described with reference to the drawings.

【0028】

FIG. 2 is a typical diagram in the case of executing multi-hop communication between wireless communication terminals according to the embodiment of the present invention. FIG. 2 shows a case where multi-hop communication is executed from the terminal 201 to the terminal 203 and a case where the multi-hop communication is executed from the terminal 204 to the terminal 207.

【0029】

When multi-hop communication is executed from terminal 201 to terminal 203, terminal 202 becomes a relay station, and when multi-hop communication is executed from terminal 204 to terminal 207, terminal 205 and terminal 206 become relay stations.

【0030】

As shown in FIG. 2, in multi-hop communication, information is transmitted from a terminal that is a source to a terminal that is a final destination, so that the terminal relays the information as a relay station.

【0031】

FIG. 3 is a functional block diagram showing a communication function unit built in the wireless communication terminal according to the embodiment of the present invention. As shown in FIG. 3, the communication function unit 10 built in the wireless communication terminal includes a memory 2, a baseband processing unit 14, a frequency conversion circuit 8, and a wireless antenna 12. The baseband processing unit 14 is composed of a MAC (Media Access Control) unit 4 and a modem unit 6.

【0032】

The memory 2 is connected to the MAC unit 4 and provides a work area, a frame buffer, and the like for the MAC unit 4. The MAC unit 4 creates a MAC header attached to transmission data, controls access to a MAC frame, and the like. The modem unit 6 connected to the MAC unit 4 executes PLCP (Physical Layer Convergence Protocol) header processing, frequency diffusion and phase modulation processing, A / D conversion processing, and the like. The frequency conversion circuit 8 connected to the modem unit 6 is a circuit that gradually converts the frequencies of the transmission signal and the reception signal for internal signal processing and radiating radio waves from the wireless antenna 12. .. This circuit complies with, for example, the IEEE 802.11 wireless LAN system.

【0033】

(First Embodiment) FIG. 4 is a diagram showing a configuration including a MAC header portion of a data packet according to the first embodiment of the present invention. FIG. 4 shows a configuration example of the MAC header portion in the data packet when the terminals take the IBSS communication mode in the IEEE802.11 wireless LAN system. IEEE 802.11, which defines the physical layer and media access control layer (MAC layer), provides four address fields in the MAC header section.

【0034】

In the present embodiment, 6 octet address fields are provided in the latter half of the MAC header section, and the address 1, address 2, address 3, 2 octet sequence control field, and 6 octet address field are used in this order. ..

【0035】

Such a data packet configuration is transmitted to another terminal base station as a relay station in order to transfer the received data packet to another terminal by the terminal base station that received the data packet from the terminal in BSS (Basic Service Set). However, the address information and BSSID written in each address field are different from those of the present embodiment.

【0036】

That is, in the three address fields of address 1, address 2, and address 3, the address of the terminal that is the final destination (Destination Address: DA) and the address of the source terminal that generated and transmitted the information (Source Address:), respectively. The BSSID, which is the identification number of SA) and BSS, is written, and the address (Receiver Address: RA) of the direct destination relay station of the current data packet is written in the address field of address 4.

【0037】

This makes it possible to handle address control related to multi-hop communication in IBSS at the MAC layer level, and eliminates the need to entrust address control to a higher level.

【0038】

FIG. 5 is a flowchart showing address processing in the communication function unit 10 on the terminal side that generates and transmits data packets when the wireless communication terminal according to the first embodiment of the present invention realizes multi-hop communication. When the communication function unit 10 receives the transmission data packet from the upper layer to the MAC layer, the communication function unit 10 refers to the frame control field of the transmission data packet and determines whether or not the communication mode is IBSS (step S1). When transmitting a transmission data packet, it may be determined whether or not the communication mode of the transmission data packet is IBSS, not for each data packet but for several data packets at once. If it is determined that the communication form of the transmitted data packet is IBSS, the process proceeds to step S2, while if it is determined that the communication form of the transmitted data packet is not IBSS, the process proceeds to step S4 and the data packet is transmitted (). Step S4).

【0039】

If it is determined that the data packet is IBSS in step S1, it is determined whether or not the data packet is transmitted to the DA terminal by multi-hop communication (step S2). If it is determined that the data packet is transmitted to the DA terminal by multi-hop communication, the process proceeds to step S3. On the other hand, if it is determined that the data packet is not transmitted to the DA terminal by multi-hop communication, the process proceeds to step S4. Process the packet for transmission (step S4). When it is determined in step S2 that the data packet is transmitted to the DA terminal by multi-hop communication, first, the next terminal to transmit the data packet is selected by some routing selection process (step S3). Next, the MAC ID corresponding to the address of the selected terminal is set to RA, an area of 6 octets is secured as the address 4 in the MAC header part of the data packet, and the value of RA is written in the area (step S3). .. Then, the data packet is transmitted and processed (step S4).

【0040】

FIG. 6 is a flowchart showing address control in reception processing on the terminal side that functions as a relay station when the wireless communication terminal according to the first embodiment of the present invention realizes multi-hop communication. When a data packet is received from a certain terminal, it is determined whether the communication mode is IBSS by referring to the frame control field of the received data packet (step S11). As in the case of transmission described above, the process may be performed for a number of data packets at once instead of for each data packet.

【0041】

When it is determined that the communication mode of the received data packet is IBSS, it is determined whether or not the DA included as information in the data packet matches the MAC ID of the terminal which is the relay station (step S12). ). If the DA matches the MAC ID of the relay station, the process proceeds to normal reception processing (step S13). On the other hand, if the DA does not match the MAC ID of the relay station, the NAV (Network Allocation Vector) is usually set, but in the present embodiment, the sequence control of the MAC header part is used in the received data packet. Extract the following 6 octets as the address field of address 4 and use this as RA (step S14). One octet consists of eight consecutive bits.

【0042】

Further, it is determined whether or not the RA included as information in the data packet matches the MAC ID of the relay station (step S15). Here, if RA does not match the MAC ID of the relay station, the 6 octets extracted as RA in the previous step are determined to be the frame body of the received data packet, and these 6 octets are returned to the beginning of the frame body (step S18). ), Move to the normal NAV setting process (step S19). The present invention is not limited to the process of performing the NAV setting process as the process of step S19.

【0043】

On the other hand, if the 6-octet portion set as RA in step S15 matches the MAC ID of the relay station, the next terminal to transmit the data packet is selected by performing some routing control (step S16). Then, the MAC ID of the selected terminal is set to RA, and the 6 octets of the address field of address 4 described above are updated by this new RA (step S16), and the data packet is transmitted (step S17).

【0044】

As described above, in the present embodiment, the terminal that has received the data packet transmitted by the terminal that intends to perform multi-hop communication in IBSS refers to the MAC header part and is its own terminal the final destination terminal. Determine if not (step S12). If the terminal itself is not the final destination terminal, the terminal forwards the received data packet to another terminal (step S17). As a result, relay transmission of wireless communication data packets, that is, multi-hop communication is realized.

【0045】

The operation at the terminal that relays the data packet can be the same as the operation at the MAC layer level when the terminal base station in BSS functions as a relay station, and the address control at the MAC layer of the existing terminal base station. By simply adding a part of the function to the terminal, it is possible to easily realize a relay terminal capable of supporting multi-hop communication.

【0046】

By adding additional functions to the basic functions of inter-terminal communication in this way, even in a system in which terminals having no additional functions not corresponding to the present embodiment and terminals corresponding to the present embodiment coexist. Communication between terminals is not hindered. Specifically, when a terminal that does not support multi-hop communication receives a data packet intended for multi-hop communication according to the present invention, the address (DA) of the terminal that is the final destination is set in the reception process at the MAC layer level. Compare with the address of its own terminal (step S12). When the DA matches the address of its own terminal, it receives and processes the data packet (step S13), but when it does not match, it sets the NAV (step S19).

【0047】

Further, when multi-hop communication is performed between the terminals according to the present invention in the mixed system, the transmission output during the multi-hop communication can be suppressed, and the interference in the entire system can be reduced.

【0048】

(Second Embodiment) FIG. 7 is a diagram showing a configuration including a MAC header portion of a data packet according to the second embodiment of the present invention. The second embodiment will be described focusing on the differences from the first embodiment. The difference between this embodiment and the first embodiment is that in the data packet configuration for multi-hop communication of the first embodiment shown in FIG. 4, the current data packet is directly displayed in the field of address 3 instead of the BSSID. It is to write the address (Transmitter Address: TA) of the transmitting terminal that is the source of.

【0049】

FIG. 8 is a flowchart showing address processing in the transmission unit on the terminal side that generates and transmits data packets when the wireless communication terminal according to the second embodiment of the present invention realizes multi-hop communication. As the address TA is written, in the present embodiment, the address processing (step S20) for writing the TA in addition to the RA is added in the processing procedure at the time of transmission in the first embodiment shown in FIG. To.

【0050】

That is, when it is determined in step S2 that the data packet is transmitted to the DA terminal by multi-hop communication, the address of the terminal is written to the TA (step S20). After that, the process proceeds to step S3. The other steps are the same as the address processing in the first embodiment.

【0051】

FIG. 9 is a flowchart showing address control in reception processing on the terminal side that functions as a relay station when the wireless communication terminal according to the second embodiment of the present invention realizes multi-hop communication. As the address TA is written to the address field, in this embodiment, during the reception processing at the relay station in the first embodiment shown in FIG. 6, the 6 octets following the sequence control field are RAed. If it is determined to exist, the field at address 3 is determined to be TA instead of BSSID.

【0052】

That is, in step S14, the 6 octets following the sequence control of the MAC header part included in the received data packet are extracted as the address field of the address 4, this address field is set to RA, and then the field of the address 3 is determined to be TA. The other steps are the same as the address control in the first embodiment.

【0053】

The terminal that functions as a relay station performs a process of selecting some routing to the terminal that is the final destination indicated in the DA. As a result, when a determination result is obtained that it is preferable to use another relay station other than the relay station, the determination result is notified to the previous terminal having the TA as the MAC ID that transmitted the received data packet. Upon receiving this determination notification, the previous terminal can feed it back to the routing selection process in the terminal itself.

【0054】

A data packet in a multi-hop communication mode is transmitted to the relay station, and the previous terminal indicated as TA in the field of address 3 in the MAC header portion of the data packet is relayed from the relay station to a relay station other than the relay station. As a result of receiving a judgment that it is preferable to use a station as a notification and feeding it back to the routing selection process, when the previous terminal receives the data packet, it is indicated as TA in the address field of address 3 in the MAC header section. A notification that the previous terminal has fed back to the routing selection process may be transmitted to the previous terminal.

【0055】

As described above, by describing TA in the address field of address 3 of the MAC header part of the data packet transmitted using the form of multi-hop communication, the data packet is the result of the relay station executing the routing selection process. It is possible to feed back to the previous transmitting terminal, and further to the previous transmitting terminal, and the routing table can be updated in response to the movement of the terminal and the change in the radio propagation environment.

【0056】

(Third Embodiment) The third embodiment will be described focusing on the differences from the first embodiment. The difference between this embodiment and the first embodiment is the form of multi-hop communication in which the address of the final destination must be set by the unicast address.

【0057】

FIG. 10 is a typical diagram when multi-hop communication is executed between the wireless communication terminals according to the third embodiment of the present invention. In the case of communication using a unicast address, as shown in FIG. 10, the address (that is, DA) of the terminal that is the final destination of the data packet is fixed to one. In the case of FIG. 10, the data packet is transmitted from the relay station 101 to the relay station 103, and the data packet is transmitted from the relay station 103 to the relay station 104 which is the DA.

【0058】

FIG. 11 is a flowchart showing address control in reception processing on the terminal side that functions as a relay station when the wireless communication terminal according to the third embodiment of the present invention realizes multi-hop communication.

【0059】

Also in this embodiment, similarly to the processing related to the address control in the reception processing on the relay station side functioning as the relay station in the first embodiment shown in FIG. 6, it is first determined whether or not the IBSS is used (step). S11). If it is IBSS, it is determined whether the DA matches the MAC ID of the relay station (step S12).

【0060】

If the DA does not match the MAC ID of the relay station in step S12, in the present embodiment, it is first determined whether or not the address field (DA) of address 1 in the MAC header section is a group address (step S22). .. Here, the group address is an address that collectively indicates a plurality of addresses. If the address field (DA) of address 1 is a group address in step S22, it is determined that the field of address 4 does not exist in the data packet, and the process immediately proceeds to the NAV setting process (step S23).

【0061】

On the other hand, if the address field (DA) of address 1 is not a group address in step S22, the process proceeds to step S14. The other steps are similar to the address control in the first embodiment shown in FIG.

【0062】

According to such a third embodiment, it is possible to easily determine whether the data packet is related to multi-hop communication, and if not, it is possible to quickly shift to normal reception processing (NAV setting processing, etc.). ..

【0063】

Here, the creation and update of the routing table applicable to the first to third embodiments described above will be described with reference to the fourth to ninth embodiments.

【0064】

(Fourth Embodiment) FIG. 12 is a typical diagram in the case of executing multi-hop communication between wireless communication terminals according to the fourth embodiment of the present invention. When the relay station 101 in the IBSS transmits a beacon signal having a constant transmission power level within the range of the transmission power allowed by the system, the relay stations 102 and 103 receive the beacon signal from the relay station 101. Each relay station that has received this beacon signal records in the routing table that the own relay station has that it can directly communicate with the relay station 101.

【0065】

FIG. 13 shows a routing table of each relay station to be referred to when the wireless communication terminal according to the fourth embodiment of the present invention functions as a relay station. In the routing table, the address (DA) of the relay station which is the final destination, the address (RA) of the relay station which is the direct destination of the current data packet corresponding to the DA, and the communicable station are written. In addition to the communicable station, the reception level of the beacon signal from the communicable station is also written.

【0066】

In the example shown in FIG. 12, when the relay stations 102 and 103 receive the beacon signal from the relay station 101, 101 is written in the communicable station column of the routing table of each of the relay stations 102 and 103. Further, whether or not the reception level at which the respective relay stations 102 and 103 have received the beacon signal is high is also written in the respective routing table.

【0067】

As a result, when the relay station 102 or the relay station 103 receives the data packet related to the multi-hop communication, these relay stations make the relay station 101 a candidate for the relay station to which the data packet should be transmitted next. Will be able to.

【0068】

Further, when the relay station 102 transmits a beacon signal having a constant transmission power level as in the relay station 101, in this case, the relay station 101 and the relay station 104 receive the beacon signal from the relay station 102. Then, as shown in FIG. 13, the relay station 101 and the relay station 104 record in their own routing table that they can directly communicate with the relay station 102.

【0069】

By each relay station following the above procedure, a routing table that describes the relay station of the other party with which each relay station can directly communicate with IBSS is constructed.

【0070】

Further, when the relay station 101 notifies the relay station 102 of its own routing table, it is found that the relay station 102 can also communicate with the relay station 103, and the relay station 102 wants to transmit information to the relay station 103. As shown in 13, record in its own routing table that relay station 101 is a candidate for relay station. By notifying other relay stations capable of direct communication of the routing table owned by each relay station in this way, each relay station can increase the information of the other relay station and update the routing table. become.

【0071】

Each relay station having the routing table generated and updated as described above should transmit next when generating a data packet related to multi-hop communication for transmission or when relaying the data packet. The relay station can be selected appropriately.

【0072】

(Fifth Embodiment) In the fifth embodiment, the above-mentioned routing table is updated based on the processing of the authentication signal.

【0073】

FIG. 14 is a typical diagram when multi-hop communication is executed between the wireless communication terminals according to the fifth embodiment of the present invention.

【0074】

As shown in FIG. 14, when the relay station 101 provides authentication to the relay station 102, the communication route between the relay station 101 and the relay station 102 becomes more reliable. This communication route has a higher priority than the communication route with the relay station 103 that has not been given authentication, for example, in the routing table of the relay station 101.

【0075】

For example, when a data packet related to multi-hop communication is transmitted from a relay station 101 to a relay station 105, there are two routes that relay either the relay station 102 or the relay station 103. In this case, the relay station 102 to which the authentication is given is selected as the relay station to which the relay data packet should be transmitted next.

【0076】

FIG. 15 is a routing table to be referred to when the wireless communication terminal according to the fifth embodiment of the present invention functions as a relay station. This routing table is owned by the relay station 102. When the relay station 102 has a routing table with high priority of the communication route between the relay station 101 and the relay station 102, or as described above, the relay station 101 gives the relay station 102 an authentication. In this case, when the relay station 102 receives the data packet related to the multi-hop communication from the relay station 104 to the relay station 103, the relay station 102 refers to the relevant routing table and selects the relay station 101 over the relay station 105. ..

【0077】

According to the fifth embodiment described above, by using the routing table, it is possible to realize multi-hop communication in consideration of the reliability of the communication route at the time of relay.

【0078】

(Sixth Embodiment) In the sixth embodiment, data packets of RTS (Request to Send) signal and CTS (Clear to Send) signal are exchanged, and a routing table at each relay station is created based on the processing result. Update.

【0079】

FIG. 16 is a typical diagram when multi-hop communication is executed between the wireless communication terminals according to the sixth embodiment of the present invention. For example, as shown in FIG. 16, when the relay station 101 transmits an RTS signal to the relay station 103 and the relay station 103 receives this, the relay station 103 transmits the corresponding CTS signal to the relay station 101. On the premise of this, the relay stations move between the relay stations or one of them, or the radio propagation environment between the relay stations 101 and the relay station 103 changes due to an external factor, and the relay station 103 If cannot receive the RTS signal from the relay station 101, the relay station 101 determines that the CTS signal has not been transmitted after waiting for the CTS signal from the relay station 103 for a certain period of time. Further, the relay station 101 updates the routing table owned by the relay station 101 by excluding the relay station 103 from the candidates of terminals capable of direct communication or lowering the priority of the communication route with the relay station 103. The same applies when the CTS signal transmitted by the relay station 103 to the relay station 101 cannot be received by the relay station 101. Conversely, if the RTS and CTS signals are successfully exchanged, the channels in between will have higher priority.

【0080】

The routing table of the relay station 101 updated in this way can be notified from the relay station 101 to the relay station 102 and can also be used for updating the routing table in the relay station 102. The sixth embodiment described above has the same effect as the fifth embodiment described above.

【0081】

(7th Embodiment) FIG. 17 is a typical diagram in the case of executing multi-hop communication between wireless communication terminals according to the 7th embodiment of the present invention. When the broadcast address is written as RA in the relay station 101, the radio waves emitted by the relay station 101 can be received and relayed by all the relay stations to which the radio waves reach.

【0082】

If the routing table is only generated and no information about any terminal is obtained, and there is no information in the routing table for transmitting or relaying data packets related to multi-hop communication to the terminal that is the final destination, this implementation is performed. As shown in FIG. 18, the terminal according to the mode writes the broadcast address in the address field of the address 4 for writing the address of the terminal to be transmitted next. For example, as a broadcast address, write 1 to all bits of the address field at address 4. Here, FIG. 18 is a diagram showing a configuration including a MAC header portion of the data packet according to the seventh embodiment of the present invention.

【0083】

This intentionally allows the generated data packet for multi-hop communication to reach the final destination terminal even if not all terminals in the wireless communication system have a completely closed routing table. Can be given to.

【0084】

Needless to say, even when the routing table created or updated according to the fourth to sixth embodiments described above exists, the processing according to the seventh embodiment may be performed.

【0085】

(Eighth Embodiment) FIG. 19 is a typical diagram in the case of executing multi-hop communication between wireless communication terminals according to the eighth embodiment of the present invention.

【0086】

In the fourth to sixth embodiments described above, the relay station that generates or relays the data packet related to the multi-hop communication selects the relay station to be transmitted next for transmission to the relay station that is the final destination. When performing based on the routing table, one candidate cannot be selected because the selection conditions are the same or close to each other, that is, there are a plurality of relay station candidates.

【0087】

FIG. 19 shows a case where a data packet is transmitted from the relay station 101 to the relay station 105 by relaying the relay stations 102 and 103.

【0088】

In this case, as shown in FIG. 20, the addresses of the plurality of relay station candidates are written as multicast addresses in the address field of address 4 for writing the address RA of the relay station to be transmitted next.

【0089】

Here, FIG. 20 shows a configuration including a MAC header portion of the data packet according to the eighth embodiment of the present invention.

【0090】

As a result, the data packet related to the multi-hop communication can be transmitted via the plurality of routes, and the data packet can be more reliably reached to the relay station of the final destination.

【0091】

(9th Embodiment) In the 7th embodiment described above, when the data packet related to the multi-hop communication transmitted or relayed by broadcasting reaches the relay station which is the terminal of the final destination, the terminal is the final destination. On the contrary, the relay station generates and transmits a new data packet related to multi-hop communication to the relay station of the transmission source. This data packet reaches the relay station of the other party by the reverse routing.

【0092】

FIG. 21 is a typical diagram when multi-hop communication is executed between the wireless communication terminals according to the ninth embodiment of the present invention. In the example shown in FIG. 21, the data packet transmitted from the relay station 101 of the transmission source reaches the relay station 105, which is the final destination, via the relay station 102. As an example of the reverse routing, there is a route in which a data packet transmitted from the relay station 105 reaches the relay station 101 via the relay station 103.

【0093】

As a result, when the relay station that initially generated or relayed the data packet related to multi-hop communication performs the next transmission to the relay station that is the same final destination, the information of the data packet exchange reached by the reverse routing. Based on this, it becomes possible to specify multiple or one relay station candidates to be transmitted next and update the routing table owned by the own relay station.

【0094】

FIG. 22 shows how the routing table of the wireless communication terminal according to the ninth embodiment of the present invention is updated in the case of multi-hop communication by broadcasting. The data packet arriving at the relay station 101 according to the route shown in FIG. 21 also includes the reception information (for example, reception level information) of the data packet for the relay station 101 of the relay stations 102 and 103 as data. Based on this received information, the routing table provided in the relay station 101 is updated as shown in FIG. 22. According to this routing table, when the final destination is the relay station 105, it can be seen that more stable data communication is possible by selecting the relay station 103 as the relay station rather than the relay station 102. According to such a ninth embodiment, it is possible to enhance the comprehensiveness of the communication route related to the multi-hop communication.

【0095】

In the eighth embodiment described above, when the data packet related to the multi-hop communication transmitted or relayed by designating the multicast address reaches the relay station of the final destination, it is the same as the case where the broadcast address described above is specified. In addition, a data packet related to new multi-hop communication may be generated and transmitted from the terminal that is the final destination to the terminal that is the transmission source. This data packet reaches the destination terminal by the reverse routing.

【0096】

As a result, when the terminal that initially generated or relayed the data packet related to multi-hop communication performs the next transmission to the terminal that is the same final destination, it is based on the data packet exchange information reached by the reverse routing. Then, it becomes possible to specify multiple or one terminal candidates to be transmitted next and update the routing table owned by the own terminal.

【0097】

FIG. 23 shows how the routing table of the wireless communication terminal according to the ninth embodiment of the present invention is updated in the case of multi-hop communication by multicast. As in the case of the multi-hop communication by broadcasting described above, the data packet arriving at the relay station 101 also includes the received information of the data packet to the relay station 101 of the relay stations 102 and 103 as data. Based on this received information, the routing table provided in the relay station 101 is updated as shown in FIG. 23. According to the routing table before the update, the reception level of both relay stations 102 and 103 was low for the relay station 101. However, according to the updated routing table, when the final destination is the relay station 105, it can be seen that more stable data communication is possible by selecting the relay station 103 as the relay station rather than the relay station 102. .. Since the radio wave communication environment is changing from moment to moment, it is possible to obtain a routing table that is more suitable for the situation at that time than the previous routing table by updating it. According to such a ninth embodiment, the completeness of the communication route related to the multi-hop communication can be further enhanced.

【0098】

(10th Embodiment) In the 10th embodiment, in the 4th to 6th embodiments described above, a field for describing the number of relay stations is provided in the data packet.

【0099】

FIG. 24 is a typical diagram when multi-hop communication is executed between the wireless communication terminals according to the tenth embodiment of the present invention. In FIG. 24, when the relay station 101 transmits a data packet with the relay station 104 as the final destination terminal, if the relay station 102 is used as the relay station, the relay station 102 sends the data packet toward the relay station 104. If the data packet is transmitted and the relay station 104 succeeds in receiving the data packet, it can be seen that the required number of relay stations (stations) is 1 (relay station 102) on the relay station 104 side. This is because the relay station that relayed adds one value to each of the fields that describe the number of relay stations.

【0100】

On the other hand, when the relay station 101 first selects the relay station 103 as the relay station, the data packet cannot be directly transmitted from the relay station 103 to the relay station 104, and another relay station, for example, the relay station 105, is used as the relay station. Must be used as.

【0101】

In this case, on the relay station 104 side, it can be seen that the required number of relay stations was 2 when the data packet transmitted from the relay station 101 was received from the relay station 105.

【0102】

Therefore, conversely, when the relay station 104 sends a data packet related to multi-hop communication with the relay station 101 as the final destination terminal, the direct transmission is performed next in order to select a communication route with a smaller number of relay stations. The relay station 102 can be selected as the other party terminal of.

【0103】

FIG. 25 shows a configuration including a MAC header portion of the data packet according to the tenth embodiment of the present invention. In the relay station field for writing the number of relay stations, a number is written in the relay station field as shown in FIG. This number indicates the total number of relay stations, which is the number of relay stations relayed so far. For example, in the data packet that arrived at the relay station 104 from the relay station 101 via the relay station 102 in FIG. 24, the total number of relays is 1 corresponding to one of the relay stations 102. Further, in the data packet arriving at the relay station 104 from the relay station 101 via the relay stations 103 and 105 in FIG. 24, the total number of relay stations is 2 corresponding to the two relay stations 103 and 105.

【0104】

For example, when the relay station 101 sends out a data packet with the relay station 104 as the final destination terminal, the two terminals described in the routing table that direct communication is possible, that is, the relay station 102 and the relay station 103. When it is not possible to determine which one should be selected as the relay station, the addresses of the relay station 102 and the relay station 103 are described in the address 4 as the multicast address, and the data packet is transmitted.

【0105】

As described above, when the relay station 104 receives the data packet from the relay station 102 as the number of relay stations 1 and from the relay station 105 as the number of relay stations 2, the relay station 104 designates the relay station 102 as the relay station. And sends a response frame to the relay station 101. Then, when the relay station 101 receives the response frame, from the next time onward, the relay station 102 is informed that the relay station 102 should be used when transmitting a data packet with the relay station 104 as the final destination terminal. It can be described as information in the 101 routing table.

【0106】

Further, when the relay station 104 further acts as a relay station and transmits a data packet from the relay station 101 which is the source terminal, the same information is provided from the relay station 102 and the relay station 105 except for the field for describing the number of relay stations. If the data packets that are the same are received in duplicate, by comparing the fields of these two data packets to stop the relay of the data packet with the larger number of relay stations, the communication route will be different. It is possible to prevent an increase in data packet communication of the same information.

【0107】

(11th Embodiment) The wireless communication terminal of this embodiment is a case where an upper limit of the number of relay stations capable of relaying a data packet transmitted from a relay station of a transmission source is set.

【0108】

FIG. 26 is a typical diagram when multi-hop communication is executed between the wireless communication terminals according to the eleventh embodiment of the present invention. In FIG. 26, when the relay station 101 sends out a data packet related to multi-hop communication with the relay station 104 as the final destination terminal, when it is not possible to determine which terminal should be used as the relay station, the multicast address. Alternatively, in the above-described embodiment in which the group address, which is a broadcast address, is described in address 4 and a data packet is transmitted, the maximum number of relay stations allowed is set to 2.

【0109】

If the relay station 103 that receives the data packet from the relay station 101 does not have information about the relay station 104 in its routing table, it cannot determine which terminal is to be used as the next relay station, and the multicast address or broadcast The group address, which is the address, is described in address 4, and the field in which the number of relay stations is described is rewritten with the value "1" obtained by subtracting the relay station of the user as the allowable number of relay stations, and the data packet is sent.

【0110】

Similarly, when the relay station 106 that receives the data packet from the relay station 103 does not have the information of the relay station 104 in its own routing table, the group address is described in the address 4 and the number of relay stations allowed is set as the number of relay stations. The field for describing the number of relay stations is rewritten with the value "0" obtained by subtracting, and a data packet is sent. If the terminal that received the data packet is not the relay station 104, no further relay can be performed, so the relay is stopped.

【0111】

FIG. 27 shows a configuration including a MAC header portion of the data packet according to the eleventh embodiment of the present invention. The number written in the relay station field shown in FIG. 27 is when the upper limit (possible number of relays) of the number of relay stations in which the data packet transmitted from the transmission source relay station can be relayed is 2. Is an example of.

【0112】

Every time the data packet transmitted from the relay station of the transmission source passes through the relay station, 1 is subtracted from the number written in the relay station field. For example, in the data packet transmitted from the relay station 101 of the source, the initial value 2 of the number of possible relays is written in the relay station field. After that, 1 is written in the relay station field of the data packet that has passed through the relay station 103 because 1 is subtracted by the relay station 103. Next, when the data packet received by the relay station 106 confirms that the relay station 106 is not the final destination by the MAC ID of the relay station 106, any further relay operation is stopped.

【0113】

According to the eleventh embodiment as described above, when the routing from the source terminal to the final destination terminal is not established in the entire system, the transmitted data packet takes a plurality of communication routes. It becomes possible to prevent the data packet from diverging in the system due to repeated relaying.

【0114】

(Twelfth Embodiment) The twelfth embodiment relates to the combination of the tenth embodiment and the eleventh embodiment described above, and performs a process of grasping the number of relay stations and a process of stopping by the maximum number of relay stations. Is. In the tenth embodiment, the maximum number of relay stations allowed when transmitting a data packet at a terminal that is a source of data packet information is defined and described in the above-mentioned relay station field.

【0115】

An operation for relaying when the number of relay stations is intended to be grasped by setting a reference value in the field for describing the number of relay stations, and for relaying when the maximum allowable number of relay stations is specified. Unify operations.

【0116】

Here, for example, the reference value of the relay station field is set to 0, and the value written in the relay station field is incremented by 1 when relaying. In this case, the terminal that has received the data packet has a value larger than 0 in the relay station field in the data packet, that is, if the value is positive, the communication is for grasping the number of relay stations. On the other hand, if the value is smaller than 0, that is, the value is negative, it is judged that the maximum number of relay stations that can be tolerated is specified and the data packet is sent, and it should be 0. If so, stop the relay. If the value of the relay station field of the data packet received by the terminal is 0, it will be described later.

【0117】

FIG. 28 shows a configuration including a MAC header portion of the data packet according to the twelfth embodiment of the present invention in the case of grasping the number of relay stations. Numbers are written in the relay station field shown in Figure 28. The number written in this field indicates the number of relay stations that have already been relayed as described above, or the number of relay stations that can be relayed from now on. FIG. 28 shows the case where the reference value 0 is written. If this value has a value of 0 or more, it corresponds to the number of relay stations relayed.

【0118】

For the purpose of ascertaining the number of relay stations, when the source terminal sends a data packet, the initial value of the relay station field is set to 0 for transmission. By increasing the value of the relay station field by 1 when relaying, the relay station can grasp the number of relay stations from the terminal that is the source at each relay station and the terminal that is the final destination. ..

【0119】

FIG. 29 shows a configuration including a MAC header portion of the data packet according to the twelfth embodiment of the present invention in the case where the maximum number of allowable relay stations is specified. When the terminal, which is the source of the data packet, specifies the maximum number of relay stations that can be tolerated, the maximum number of positive relay stations is described in the field with a negative code and transmitted. The relay station that receives the data packet adds 1 to the negative value and transmits it. When relaying, if the address of the terminal that is the final destination does not exist in its own routing table, relaying may be stopped.

【0120】

When stopping relay in this way, when specifying the maximum number of relay stations that can be tolerated, set a large absolute value (for example, increase by one) when obtaining this from the optimum number of relay stations. Is preferable. This is because the terminal that is the final destination may be included in the next receiving terminal relayed by the group address even if it is not listed in the routing table.

【0121】

When the value of the relay station field is 0, the relay station that has received the data packet determines that the data packet has been sent for the purpose of ascertaining the number of relay stations. When the value of the relay station field is -1, the relay station that has received the data packet determines that the maximum number of relay stations that the data packet can tolerate is specified and transmitted.

【0122】

Even if the previous relay station transmits without stopping the relay and receives the relay station field of 0, if it is based on the second embodiment, that is, TA is described at address 3. This can be used in some cases. That is, the TA at address 3 is compared with the SA at address 2, and if they are different, it is judged that the TA is relayed and the relay station field is added by 1 to become 0. In other words, if the TA at address 3 and the SA at address 2 are different, it is determined that the data packet was sent by specifying the maximum number of relay stations that can be tolerated.

【0123】

According to the twelfth embodiment described above, the optimum number of relay stations to each terminal can be grasped, and the maximum relay when a data packet is generated with another terminal as the final destination by referring to the number of relay stations can be grasped. You can also set the number of stations.

【0124】

The effects obtained by the first to twelfth embodiments described above are summarized below.

【0125】

Multi-hop communication is realized by adding the relay function used by the terminal base station in BSS to the terminal-to-terminal communication in IBSS. Implementation at the MAC layer is easy, and it is effective for prompt response to make terminals perform multi-hop communication. By adding additional functions to the basic functions of inter-terminal communication in this way, communication between these terminals is not hindered even in a system in which terminals that do not correspond to the present invention coexist. Further, when multi-hop communication is performed between the terminals according to the present invention in the mixed system, the transmission output in the multi-hop communication can be suppressed, and the interference in the entire system can be reduced.

【0126】

Further, by describing the TA in the data packet transmitted in the multi-hop communication form, the result of the relay station executing the routing selection process can be fed back to the previous terminal that transmitted the data packet, and this can be fed back. Furthermore, it is possible to feed back to the transmitting terminal before that. Therefore, the routing table can be updated in response to the movement of terminals and changes in the wireless propagation environment.

【0127】

In addition, when taking the form of multi-hop communication in which the address of the terminal that is the final destination is always set by a single unicast address, it accompanies the determination of the address in the reception processing by the terminal that functions as a relay station. In the processing, if it is IBSS and the DA does not match the address of the relay station and is a group address, it is determined that the received data packet is not a multi-hop data packet, and the process proceeds to the NAV setting process. .. This makes it possible to simplify the processing at the terminal that has received the data packet.

【0128】

Further, by generating and updating the routing table in each terminal, each terminal can select the terminal to be transmitted next based on the routing table when generating or relaying the multi-hop data packet.

【0129】

When the routing table is held in each terminal, a highly reliable routing table can be held by exchanging data packets related to authentication. When there are a plurality of routes, a more reliable route can be selected, and reliable multi-hop communication can be realized.

【0130】

Further, the data packets of the RTS / CTS signal may be exchanged, and a highly reliable routing table can be held to realize reliable multi-hop communication.

【0131】

In addition, by writing the broadcast address to address 4, the generated multi-hop data packet is the final destination even if all the terminals in the wireless communication system do not have a completely closed routing table. It can give the possibility of reaching the terminal.

【0132】

In addition, when there are multiple candidates for the next terminal to be transmitted in the routing table, by writing the multicast address to address 4, the multihop data packet is transmitted via multiple routes, and the final destination is more reliable. The data packet can be delivered to a terminal.

【0133】

In addition, the terminal that generated or relayed the previous multi-hop data packet, when transmitting to the terminal that is the previous final destination, of the terminal that should be transmitted next based on the data packet exchange information reached by the reverse routing. The number of candidates can be reduced or specified as one, and the routing table held can be updated.

【0134】

By providing a field to describe the number of relay stations in the multi-hop data packet and reflecting the information related to the number of relay stations in the routing table held by each terminal, a route with a smaller number of relay stations can be obtained based on the information. You will be able to select.

【0135】

In addition, by specifying the maximum number of relay stations and generating and transmitting multi-hop data packets, it is transmitted when the routing from the source terminal to the final destination terminal has not been established for the entire system. It is possible to prevent the data packets from being diverged in the system due to overlapping relays via multiple routes.

【0136】

In addition, the optimum number of relay stations at each terminal can be grasped, and the maximum number of relay stations can be set when a data packet is generated with another terminal as the final destination terminal by referring to the optimum number of relay stations.

【0137】

[Effect of the invention]

According to the wireless communication system and the wireless communication terminal of the present invention, an address control function for relay transmission of wireless communication packets is additionally provided, and multi-hop communication at the MAC layer level can be performed without changing the existing basic configuration. It can be easily realized.

[Simple explanation of drawings]

[Figure 1]

A typical diagram showing the IBSS configuration of an IEEE 802.11 wireless LAN system that performs communication between conventional wireless communication terminals.

[Figure 2]

FIG. 5 is a typical diagram when multi-hop communication is executed between wireless communication terminals according to the embodiment of the present invention.

[Fig. 3]

The functional block diagram which shows the communication function part built in the wireless communication terminal which concerns on embodiment of this invention.

[Fig. 4]

The figure which shows the structure including the MAC header part of the data packet which concerns on 1st Embodiment of this invention.

[Fig. 5]

The flowchart which shows the address processing in the transmission part of the terminal side which generates and transmits the data packet when the wireless communication terminal which concerns on 1st Embodiment of this invention realizes multi-hop communication.

[Fig. 6]

The flowchart which shows the address control in the reception processing of the terminal side which functions as a relay station when the wireless communication terminal which concerns on 1st Embodiment of this invention realizes multi-hop communication.

[Fig. 7]

The figure which shows the structure including the MAC header part of the data packet which concerns on 2nd Embodiment of this invention.

[Fig. 8]

The flowchart which shows the address processing in the transmission part of the terminal side which generates and transmits the data packet when the wireless communication terminal which concerns on 2nd Embodiment of this invention realizes multi-hop communication.

[Fig. 9]

The flowchart which shows the address control in the reception processing of the terminal side which functions as a relay station when the wireless communication terminal which concerns on 2nd Embodiment of this invention realizes multi-hop communication.

[Fig. 10]

FIG. 5 is a typical diagram in the case of executing multi-hop communication between wireless communication terminals according to the third embodiment of the present invention.

[Fig. 11]

The flowchart which shows the address control in the reception processing of the terminal side which functions as a relay station when the wireless communication terminal which concerns on 3rd Embodiment of this invention realizes multi-hop communication.

[Fig. 12]

FIG. 5 is a typical diagram in the case of executing multi-hop communication between wireless communication terminals according to the fourth embodiment of the present invention.

[Fig. 13]

A routing table to be referred to when the wireless communication terminal according to the fourth embodiment of the present invention functions as a relay station.

[Fig. 14]

FIG. 5 is a typical diagram in the case of executing multi-hop communication between wireless communication terminals according to the fifth embodiment of the present invention.

[Fig. 15]

A routing table to be referred to when the wireless communication terminal according to the fifth embodiment of the present invention functions as a relay station.

[Fig. 16]

FIG. 5 is a typical diagram in the case of executing multi-hop communication between wireless communication terminals according to the sixth embodiment of the present invention.

[Fig. 17]

FIG. 5 is a typical diagram in the case of executing multi-hop communication between wireless communication terminals according to the seventh embodiment of the present invention.

[Fig. 18]

The figure which shows the structure including the MAC header part of the data packet which concerns on 7th Embodiment of this invention.

[Fig. 19]

FIG. 5 is a typical diagram in the case of executing multi-hop communication between wireless communication terminals according to the eighth embodiment of the present invention.

[Fig. 20]

The figure which shows the structure including the MAC header part of the data packet which concerns on 8th Embodiment of this invention.

[Fig. 21]

FIG. 5 is a typical diagram in the case of executing multi-hop communication between wireless communication terminals according to the ninth embodiment of the present invention.

[Fig. 22]

The figure which shows the mode that the routing table which the wireless communication terminal which concerns on 9th Embodiment of this invention has is updated in the case of multi-hop communication by broadcast.

[Fig. 23]

The figure which shows the mode that the routing table which the wireless communication terminal which concerns on 9th Embodiment of this invention has is updated in the case of multi-hop communication by multicast.

[Fig. 24]

FIG. 5 is a typical diagram in the case of executing multi-hop communication between wireless communication terminals according to the tenth embodiment of the present invention.

[Fig. 25]

The figure which shows the structure including the MAC header part of the data packet which concerns on the tenth embodiment of this invention.

[Fig. 26]

FIG. 5 is a typical diagram when multi-hop communication is executed between wireless communication terminals according to the eleventh embodiment of the present invention.

[Fig. 27]

The figure which shows the structure including the MAC header part of the data packet which concerns on 11th Embodiment of this invention.

[Fig. 28]

The figure which shows the structure including the MAC header part of the data packet which concerns on the twelfth embodiment of this invention in the case of grasping the number of relay stations.

[Fig. 29]

The figure which shows the structure including the MAC header part of the data packet which concerns on the twelfth embodiment of this invention in the case of specifying the maximum permissible number of relay stations.

[Explanation of symbols]

2 memory 4 MAC part 6 Modem section 8 Frequency conversion circuit 10 Communication function unit 12 wireless antenna 14 Baseband processing unit 101 relay station 102 relay station 103 relay station 104 relay station 105 relay station 106 relay station 201 relay station 202 relay station 203 relay station 204 relay station 205 relay station 206 relay station 207 relay station