JP2006279660A - Communication method, wireless device employing the same and communication system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve a problem that it is desired to determine a wireless device suitable for data transfer while suppressing increase of processing in an ad hoc network. <P>SOLUTION: A link quality measuring section 32 acquires the quality of communication with at least one adjacent terminal device, respectively. A route quality investigator 36 accepts information relating to communication quality in transferring a packet signal at least from the one adjacent terminal device at least from the one adjacent terminal device, respectively. Furthermore, based on the acquired communication quality and the information accepted in the accepting section, communication quality in transferring a packet signal is estimated at least for the one adjacent terminal device, respectively. Based on the estimated communication quality, a next hop processor 44 selects a terminal device to transfer a packet signal. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a communication technique, and more particularly to a communication method for transferring data in an ad hoc network, and a radio apparatus and a communication system using the same.

An ad hoc network is a network composed of only terminal devices without depending on the configuration of a base station device or a backbone network in a wireless communication system such as a mobile communication system. In an ad hoc network, terminal devices communicate with each other on an equal basis. A route in an ad hoc network is generally determined by a routing protocol. For example, when searching for a route using an on-demand routing protocol, the terminal device measures quality when a route request packet is transmitted, and determines a route while using the measurement result as a metric (see, for example, Patent Document 1). .)
JP 2005-33557 A

  Since an ad hoc network does not include a base station apparatus or an exchange constituting a mobile communication system, control of a signal path to be communicated, that is, control of routing is executed by a terminal apparatus. Therefore, a proactive protocol or the like is used. The proactive protocol includes DSDV (Destination Sequential Distance Vector), OLSR (Optimized Link State Routing), and the like. In the proactive protocol, the terminal devices exchange information about terminal devices that can communicate with each other, and as a result, the terminal device to which a signal is to be transmitted next in order to transmit the signal to the terminal device that is the destination. Information such as the number of terminal devices (hereinafter referred to as “hop count”) that are relayed until the signal reaches the terminal device (the combination of terminal devices that are routed to reach the terminal device is referred to as “route”) Managed by the terminal device. When receiving a signal to be relayed, the terminal device confirms the destination of the signal and selects a route that minimizes the number of hops to the signal destination. As a result, the terminal device transmits a signal to a terminal device included in the selected route and to which a signal is to be transmitted next.

  Under such circumstances, the present inventor has come to recognize the following problems. Conventionally, a route in an ad hoc network is set so that the number of hops is reduced. However, even if the route has a small number of hops, the route is not suitable for data transmission if the quality of the wireless transmission path is poor or the traffic is heavy. Further, even when the quality of the wireless transmission path and traffic are taken into consideration when selecting the route, the ad hoc network is composed of a plurality of wireless sections, so the wireless transmission paths in each of the plurality of wireless sections Quality and traffic must be taken into account, and the processing becomes complicated.

  The present inventor has recognized the above situation and made the present invention. The purpose of the present invention is to provide a communication technique for determining a wireless device suitable for data transfer while suppressing an increase in processing in an ad hoc network. That is.

  In order to solve the above-described problem, a wireless device according to an aspect of the present invention obtains communication quality between at least one adjacent wireless device in an ad hoc network in which data is sequentially transferred by a plurality of wireless devices. A reception unit that receives information on communication quality when each of the adjacent at least one wireless device transfers data from each of the at least one adjacent wireless device, and the communication quality and the reception unit acquired by the acquisition unit Based on the information received in step 1, the estimation unit estimates the communication quality when transferring data to each of at least one adjacent wireless device, and the communication quality estimated by the estimation unit And a selection unit that selects a wireless device to which the data is to be transferred.

  “Acquiring the communication quality between at least one adjacent wireless device” may accept the communication quality measured by another wireless device, or may measure the communication quality by itself. Ultimately, it is only necessary to be able to grasp the communication quality. “Communication quality when each of at least one adjacent wireless device transfers data” is a value assumed as communication quality ahead of at least one adjacent wireless device. “Communication quality when data is transferred to each of at least one adjacent wireless device” is communication quality assumed when data is transferred to each of at least one adjacent wireless device.

  According to this aspect, the communication quality at the time of transferring data to the adjacent wireless device is estimated while reflecting the information on the communication quality at the time when the adjacent wireless device transfers data. The influence of the route can be taken into consideration, and a wireless device suitable for transfer can be determined.

  The information received at the reception unit may reflect the influence of communication quality from each of at least one adjacent wireless device to the data destination wireless device. The “influence of communication quality” is an effect that causes a reduction in communication speed, and can be said to be a factor of deterioration in communication quality. Further, it is not necessary to reflect the influence of all the wireless sections up to the destination wireless apparatus, and it is only necessary to take into account the influence that particularly lowers the communication speed. In this case, since the influence of the communication quality up to the destination wireless device is reflected, the accuracy of selection of the wireless device to which data is to be transferred can be improved.

  You may further provide the detection part which detects the instruction | indication of data transfer. The acquisition unit may execute acquisition of communication quality at a predetermined timing, and the reception unit may execute reception of information when the detection unit detects an instruction. In this case, since communication quality is acquired at a predetermined timing, it is possible to follow fluctuations in communication quality.

  The estimation unit transfers data to the wireless device by selecting the lower of the communication quality between the adjacent wireless device and the communication quality when the wireless device transfers data. The communication quality at the time of performing the estimation may be estimated, and the estimation may be executed for each of at least one adjacent radio apparatus. In this case, since the worse communication quality is selected, the bandwidth that can be secured by the transfer can be grasped.

  You may further provide the execution part which performs the routing protocol with respect to an ad hoc network. The estimation unit may select, as at least one adjacent wireless device, a wireless device that can transfer data with a predetermined number of hops to the wireless device selected by the execution of the routing protocol in the execution unit. In this case, it is possible to reduce the number of candidates for at least one adjacent wireless device, thereby simplifying the processing.

  An input unit that inputs a request for transmission of the communication quality estimated by the estimation unit from another wireless device, and the communication quality estimated by the estimation unit when the input unit inputs the request, and the radio selected by the selection unit You may further provide the notification part which notifies the communication quality with respect to an apparatus. In this case, since the estimated communication quality is notified, it is possible to notify a value reflecting the communication quality in the previous route from the wireless device.

  Another aspect of the present invention is a communication system. The communication system includes a plurality of wireless devices that sequentially transfer data in an ad hoc network. Information received from each of at least one adjacent wireless device and information related to communication quality when each of the at least one adjacent wireless device transfers data and at least one adjacent wireless device The process of selecting a wireless device to which data should be transferred while estimating the communication quality at the time of transferring data for each of at least one adjacent wireless device based on the communication quality of It is sequentially executed from a wireless device close to the data destination wireless device among the devices.

  According to this aspect, the communication quality at the time of transferring data to the adjacent wireless device is estimated while reflecting the information on the communication quality at the time when the adjacent wireless device transfers data. The influence of the route can be taken into consideration, and a wireless device suitable for transfer can be determined.

  Yet another embodiment of the present invention is a communication method. This method is a communication method in a plurality of wireless devices that sequentially transfer data in an ad hoc network, and is information received from each of at least one adjacent wireless device, and at least one adjacent wireless device Based on the information on the communication quality when each of the devices transfers data and the communication quality between at least one adjacent wireless device, the data is transferred to each of at least one adjacent wireless device. The process of selecting a wireless device to which data is to be transferred while estimating the communication quality is sequentially executed from a wireless device close to the data destination wireless device among the plurality of wireless devices.

  Yet another embodiment of the present invention is also a communication method. In an ad hoc network in which data is sequentially transferred by a plurality of wireless devices, the method acquires a communication quality between at least one adjacent wireless device and each of the adjacent at least one wireless device. Each of the at least one wireless device receives the information on the communication quality when transferring data, and based on the acquired communication quality and the received information, for each of at least one adjacent wireless device, A step of estimating communication quality when transferring data, and a step of selecting a wireless device to which data is to be transferred based on the estimated communication quality.

  The information received in the receiving step may reflect the influence of communication quality from each of at least one adjacent wireless device to the data destination wireless device. The method may further include a step of detecting a data transfer instruction, wherein the acquiring step executes acquisition of communication quality at a predetermined timing, and the receiving step may execute reception of information when the instruction is detected. . The estimation step selects data for the wireless device by selecting the worse of the communication quality between the adjacent wireless device and the communication quality when the wireless device transfers data. Communication quality at the time of transfer may be estimated, and estimation may be performed for each of at least one adjacent wireless device.

  The method further comprises the step of executing a routing protocol for the ad hoc network, and the estimating step is a wireless capable of transferring data with a predetermined number of hops to a wireless device selected by executing the routing protocol as at least one adjacent wireless device. A device may be selected. A step of inputting a request for transmission of estimated communication quality from another wireless device, and a communication quality estimated in the estimating step when the request is input, and the communication quality for the wireless device selected in the selecting step And a step of notifying.

  It should be noted that any combination of the above-described constituent elements and a conversion of the expression of the present invention between a method, an apparatus, a system, a recording medium, a computer program, etc. are also effective as an aspect of the present invention.

  According to the present invention, it is possible to determine a wireless device suitable for data transfer while suppressing an increase in processing in an ad hoc network.

  Before describing the present invention in detail, an outline will be described. The embodiment of the present invention relates to a communication system constituted by a plurality of terminal devices, and the communication system further constitutes an ad hoc network. Among a plurality of terminal devices included in the ad hoc network, a packet signal transmitted from a terminal device that generates a packet signal (hereinafter referred to as a “transmission source terminal device”) is transferred by the plurality of terminal devices (hereinafter referred to as a “terminal device for transmission”). The terminal device for transfer is referred to as “transfer terminal device”), and the terminal device for reproducing the packet signal (hereinafter referred to as “destination terminal device”). Furthermore, each of the plurality of terminal devices exchanges routing information including the destination terminal device, the terminal device to which the signal should be transmitted, the number of hops, etc., and updates its own routing information based on the received routing information. . The routing information updated in this way does not reflect the characteristics of the wireless transmission path, the traffic volume (hereinafter collectively referred to as “communication quality”), and the like. The terminal device according to the present embodiment operates as follows in order to determine a terminal device suitable for data transfer while considering communication quality.

  The plurality of terminal devices measure communication quality with adjacent terminal devices at a predetermined timing, and notify the adjacent terminal devices of the result. That is, the plurality of terminal devices acquire the value of communication quality between adjacent terminal devices regardless of the transmission of the packet signal. When the packet signal is to be transferred, the predetermined terminal device receives the communication quality when the adjacent terminal device transfers the packet signal from the adjacent terminal device. At this time, if the adjacent terminal device is not adjacent to the destination terminal device, the adjacent terminal device performs the same processing. That is, processing for requesting transmission of communication quality to an adjacent terminal device is executed from the predetermined terminal device to the destination terminal device. Furthermore, the communication quality is notified in the direction opposite to the request processing, that is, in order from the terminal device closest to the destination terminal device. At that time, if the intermediate terminal device accepts a plurality of communication qualities, the intermediate terminal device selects the best communication quality among them and executes notification. That is, the communication quality assumed in the route to the destination terminal device is notified. Finally, as described above, the predetermined terminal device receives the communication quality when the adjacent terminal device transfers the packet signal. The predetermined terminal device determines the terminal device to which the packet signal should be transferred based on such communication quality.

  FIG. 1 shows a configuration of a communication system 100 according to an embodiment of the present invention. The communication system 100 includes a first terminal device 10a, a second terminal device 10b, a third terminal device 10c, a fourth terminal device 10d, a fifth terminal device 10e, and a sixth terminal device 10f, which are collectively referred to as the terminal device 10.

  The terminal device 10 has a function of transmitting, relaying, or receiving data. Here, the terminal device 10 is a wireless LAN compliant with the IEEE802.11b standard, and therefore, the transmission rate is selected from 11 Mbps, 5.5 Mbps, 2 Mbps, and 1 Mbps. The transmission rate is set autonomously by the terminal device 10. Although only the terminal device 10 is shown in the figure, a personal computer may be connected to the terminal device 10. The plurality of terminal devices 10 constitutes an ad hoc network. The first terminal device 10a corresponds to a “transmission source terminal device”, and the second terminal device 10b to the fifth terminal device 10e are “transfer terminal devices”. The sixth terminal device 10f corresponds to a “destination terminal device”. Here, although the 5th terminal device 10e from the 2nd terminal device 10b was illustrated as a path | route from the 1st terminal device 10a to the 6th terminal device 10f, another terminal device 10 may be included in addition to this.

  The transmission source terminal device transmits a packet signal to the ad hoc network. The transfer terminal device sequentially transmits packet signals from the transmission source terminal device to the destination terminal device along a route from the transmission source terminal device to the destination terminal device among a plurality of routes included in the ad hoc network. Forward. Here, as a route from the first terminal device 10a to the sixth terminal device 10f, a route passing through the second terminal device 10b and the third terminal device 10c (hereinafter referred to as “first route”), and a second terminal device 10b, a fourth terminal device 10d, and a fifth terminal device 10e (hereinafter referred to as “second route”). The destination terminal device receives the packet signal from the ad hoc network via the set plurality of routes. That is, the sixth terminal apparatus 10f reproduces information included in the packet signal.

  Here, as a premise of the present embodiment, it is assumed that the communication system 100 is executing a proactive protocol. That is, each terminal device 10 can communicate with other terminal devices 10 as “Destination (destination)”, “NextHop (terminal device to which data should be directly transmitted)”, “Metric (number of hops)”, “Sequence”. The routing information including “number”, “Install”, and “Flags” is exchanged. The terminal device 10 updates the latest routing information based on the exchanged routing information.

  Although details will be described later, the terminal device 10 determines the terminal device 10 to which the packet signal is to be transferred as follows. The terminal device 10 receives information from each of at least one adjacent terminal device 10 and information related to communication quality when each of the adjacent terminal devices 10 transfers data. Moreover, the terminal device 10 acquires in advance communication quality with at least one adjacent terminal device 10. Furthermore, the terminal device 10 estimates the communication quality when data is transferred to each of at least one adjacent terminal device 10 based on the acquired communication quality and the received information. Finally, the terminal device 10 selects the terminal device 10 to which data is to be transferred based on the estimated communication quality.

  2A to 2D show the operation principle of the communication system 100. FIG. In order to simplify the description, FIGS. 2A to 2D show the first terminal device 10a to the fourth terminal device 10d among the terminal devices 10 shown in FIG. Here, assuming that the destination terminal device is the fourth terminal device 10d, processing in the second terminal device 10b will be described. FIG. 2A shows an initial stage, and the second terminal device 10b detects the generation of a packet signal to the fourth terminal device 10d. The terminal device 10 adjacent to the second terminal device 10b corresponds to the first terminal device 10a, the third terminal device 10c, and the fourth terminal device 10d. Since the first terminal device 10a does not belong to the route to the destination terminal device, the first terminal device 10a is not a candidate for NextHop. This detection method will be described later. Therefore, the third terminal device 10c and the fourth terminal device 10d are candidates for NextHop.

  FIG. 2 (b) shows a stage following FIG. 2 (a). As described above, the second terminal device 10b has already acquired the wireless quality between the third terminal device 10c and the fourth terminal device 10d, which are adjacent terminal devices 10. However, the second terminal device 10b does not recognize the wireless quality on the route to the fourth terminal device 10d via the third terminal device 10c. As illustrated, the quality “40” for the “fourth terminal device” is held. Here, “quality” is communication quality, and as described above, is a general term for characteristics of wireless transmission paths and the like. Therefore, the quality should be indicated by a value having a predetermined dimension, but here, the quality is indicated by a dimensionless value “40” as a representative. For example, it is assumed that the closer to “100”, the better the quality. On the other hand, the second terminal device 10b has quality with the third terminal device 10c, but does not have “quality” with respect to the “third terminal device”. Therefore, the second terminal apparatus 10b transmits a packet signal (hereinafter referred to as “quality request packet signal”) requesting transmission of information relating to communication quality (hereinafter referred to as “information”) to the third terminal apparatus 10c. To do.

  FIG. 2 (c) shows a stage following FIG. 2 (b). The third terminal apparatus 10c that has received the quality request packet signal investigates the communication quality of the route to the fourth terminal apparatus 10d. Here, the candidate for NextHop is only the fourth terminal device 10d, and the third terminal device 10c has already acquired the communication quality with the fourth terminal device 10d, and this is used. As shown in the figure, it is assumed that the communication quality with the fourth terminal apparatus 10d is “60”.

  FIG.2 (d) shows the step following FIG.2 (c). The third terminal apparatus 10c transmits the communication quality “60” from itself to the fourth terminal apparatus 10d as information to the second terminal apparatus 10b. The second terminal apparatus 10b compares the received communication quality “60” with the communication quality “70” between the third terminal apparatus 10c and selects the worse communication quality. Further, the second terminal apparatus 10b substitutes the selected communication quality as the communication quality when transferring the packet signal to the third terminal apparatus 10c. As a result, the communication quality when the packet signal is transferred to the third terminal apparatus 10c is “60”. The second terminal apparatus 10b compares the communication quality “60” for the third terminal apparatus 10c with the communication quality “40” for the fourth terminal apparatus 10d, and selects the terminal apparatus 10 with the better communication quality. Here, the 4th terminal device 10d is selected as NextHop. From the above procedure, when the packet signal is transferred from the second terminal apparatus 10b to the fourth terminal apparatus 10d, when NextHop is changed to the third terminal apparatus 10c, the communication quality becomes “60”, and NextHop is changed to the fourth terminal apparatus 10d. Then, the communication quality becomes “40”. Therefore, the third terminal device 10c is selected.

  FIG. 3 shows a configuration of the second terminal apparatus 10b. The second terminal device 10b includes an antenna 12, an RF unit 14, a modem unit 16, a processing unit 18, an IF unit 20, and a control unit 22.

  The antenna 12 transmits and receives radio frequency signals. Here, the number of antennas and directivity are arbitrary. The RF unit 14 performs frequency conversion between a radio frequency signal transmitted and received by the antenna 12 and a baseband signal processed by a modem unit 16 described later. Also, amplification processing, analog-digital conversion processing, and digital-analog conversion processing are executed.

  The modem unit 16 performs modulation processing and spreading processing on the signal to be transmitted, and performs despreading processing and demodulation processing on the received signal. Also, error correction processing and the like are executed. As described above, since the terminal device 10 supports a plurality of transmission rates, the modem unit 16 corresponds to a plurality of modulation schemes. It is assumed that the modulation method used by the modem unit 16 in the modulation process is specified by the processing unit 18 or the control unit 22. The processing unit 18 executes routing processing corresponding to the ad hoc network. Details will be described later. The IF unit 20 connects a personal computer (not shown) or a wired network. The control unit 22 executes control necessary for the operation of the terminal device 10 such as timing control. In addition, although the 2nd terminal device 10b was demonstrated among several terminal devices 10 here, it is for the convenience with respect to the below-mentioned description, and the other terminal devices 10 also have the same structure.

  This configuration can be realized in terms of hardware by a CPU, memory, or other LSI of an arbitrary computer, and in terms of software, it can be realized by a program having a communication function loaded in the memory. The functional block realized by those cooperation is drawn. Accordingly, those skilled in the art will understand that these functional blocks can be realized in various forms by hardware only, software only, or a combination thereof.

  The processing unit 18 operates differently depending on whether the terminal device 10 is a transmission source terminal device, a transfer terminal device, or a destination terminal device. Here, the components of the processing unit 18 will be described in the order that the terminal device 10 is a transmission source terminal device and a transfer terminal device. In addition, description is abbreviate | omitted when the terminal device 10 is a destination terminal device. First, the processing unit 18 when the terminal device 10 is a transmission source terminal device will be described. This corresponds to the case of the first terminal device 10a of FIG.

  FIG. 4 shows the configuration of the processing unit 18. The processing unit 18 includes an interface unit 30, a link quality measurement unit 32, a link quality information table management unit 34, a route quality inspection unit 36, a transmission detection unit 38, a routing table management unit 40, a routing protocol execution unit 42, and a NextHop processing unit 44. The route quality information table management unit 46 is included.

  The interface unit 30 inputs and outputs predetermined data between the processing unit 18 and the modem unit 16 and the IF unit 20 (not shown). The interface unit 30 changes the data output destination according to the content of the data.

  The link quality measurement unit 32 measures communication quality between adjacent terminal devices 10. Further, in order to cause the adjacent terminal device 10 to measure the communication quality, the link quality measurement unit 32 controls transmission of a signal (hereinafter referred to as “measurement signal”). At that time, the link quality measuring unit 32 may control to transmit the measurement signal after receiving an instruction from the adjacent terminal device 10, or may transmit the measurement signal at a predetermined interval. You may control. Examples of communication quality include a reception level, a packet arrival rate, and a load status. As the reception level, the signal level and the noise level may be derived separately. The higher the signal level and the lower the noise level, the better the communication quality.

  The packet arrival rate indicates a rate at which packet signals are transmitted to adjacent terminal devices 10 and received correctly. As described above, since the wireless LAN supports a plurality of types of transmission rates, the link quality measurement unit 32 derives a packet arrival rate so as to correspond to a plurality of types of transmission rates. At this time, the measurement signal is transmitted while the transmission rate of the measurement signal is switched, whereby the link quality measurement unit 32 derives the packet arrival rate for each transmission rate. The load state corresponds to a load state due to communication with another terminal device 10, that is, a traffic amount. Even if the reception level is high, if the band is occupied by communication with another terminal device 10, the communication quality also deteriorates. When the link quality measurement unit 32 receives a predetermined number of measurement signals, the link quality measurement unit 32 calculates an average value of the reception levels and a packet arrival rate. However, in the wireless LAN, since the transmission status and the reception status are not symmetrical, the link quality measurement unit 32 transmits the calculation result to the terminal device 10 that is the transmission source of the measurement signal. On the other hand, the link quality measurement unit 32 receives the calculation result from the terminal device 10 that has transmitted the assumption signal.

  The link quality information table management unit 34 manages the calculation results received by the link quality measurement unit 32. Here, the link quality information table management unit 34 acquires the communication quality via the link quality measurement unit 32 at a predetermined timing. FIG. 5 shows the data structure of the link quality information table managed by the link quality information table management unit 34. As shown in the figure, an adjacent terminal device IP address column 116, a reception level column 118, a packet arrival rate column 120, and a load column 122 are included. The adjacent terminal device IP address column 116 records the IP address of the adjacent terminal device 10. Here, the adjacent terminal device 10 corresponds to, for example, the third terminal device 10c in FIG. The reception level column 118 records the reception levels separately for “Signal” and “Noise”. The reception level itself may be used. The packet arrival rate column 120 records packet arrival rates corresponding to a plurality of types of transmission rates. The load column 122 records the load.

  Returning to FIG. The routing protocol execution unit 42 executes a routing protocol for the ad hoc network. As described above, the proactive protocol is used as the routing protocol. Since the proactive protocol is a known technique, a description thereof will be omitted. The routing table management unit 40 manages the routing table generated by the routing protocol execution unit 42. FIG. 6 shows the data structure of the routing table managed by the routing table management unit 40. As shown, a destination column 110, a transmission destination column 112, and a hop number column 114 are included. The destination column 110 indicates the terminal device 10 to which the packet signal is to be finally transmitted. Here, the sixth terminal device 10f is illustrated, but it is assumed that information regarding the other terminal devices 10 is also included. The transmission destination column 112 indicates the terminal device 10 that should directly transmit the packet signal. The transmission destination column 112 corresponds to the adjacent terminal device IP address column 116 of FIG. The hop number column 114 indicates the number of hops to the terminal device 10 corresponding to the “destination”.

  Returning to FIG. The transmission detection unit 38 detects a data transfer instruction. It is assumed that the data transfer instruction is input from the IF unit 20, the control unit 22, and the like (not shown). The route quality examining unit 36 transmits a quality request packet signal to the adjacent terminal device 10 when the transmission detecting unit 38 detects the instruction. Further, the route quality survey unit 36 receives information from each of at least one adjacent terminal device 10. As described above, the information corresponds to communication quality when each of the adjacent terminal devices 10 transfers data. The information reflects the influence of communication quality from each of at least one adjacent terminal device 10 to the destination terminal device 10 of the packet signal. In order to receive information, the transmission detector 38 outputs a quality request packet signal. In the above processing, it can be said that the route quality examining unit 36 executes information acceptance when the transmission detecting unit 38 detects an instruction.

  Further, the route quality inspection unit 36 transfers data to each of at least one adjacent terminal device 10 based on the communication quality managed in the link quality information table management unit 34 and the received information. Estimate the communication quality when At that time, the route quality examining unit 36 selects the worse one of the communication quality between the adjacent terminal device 10 and the communication quality when the terminal device 10 transfers the packet signal, The communication quality when the packet signal is transferred to the terminal device 10 is estimated. For example, by selecting the worse one of the communication quality with the third terminal device 10c in FIG. 1 and the communication quality when the third terminal device 10c transfers the packet signal, the third terminal device 10c is selected. On the other hand, the communication quality when the packet signal is transferred is derived. Such processing is executed for each of at least one adjacent terminal device 10.

  Note that the route quality survey unit 36 does not need to process all adjacent terminal devices 10. That is, the route quality examining unit 36 can transfer a packet signal with a predetermined number of hops to the terminal device 10 selected by executing the routing protocol in the routing protocol executing unit 42 as at least one adjacent terminal device 10. The terminal device 10 is selected. The predetermined number of hops is set to “2”, for example. In FIG. 1, when the third terminal device 10c is selected when the packet signal is transferred from the second terminal device 10b to the sixth terminal device 10f, the first terminal device 10a is the adjacent terminal device 10. Disappear. That is, when the second terminal device 10b transfers a packet signal to the first terminal device 10a, the third terminal device 10c requires three hops. It will not be done. This corresponds to a route passing through the second terminal device 10b, the first terminal device 10a, the second terminal device 10b, and the third terminal device 10c.

  The NextHop processing unit 44 selects the terminal device 10 to which the packet signal should be transferred based on the communication quality estimated by the route quality examining unit 36. In addition, the NextHop processing unit 44 notifies the routing protocol execution unit 42 of information related to the selected terminal device 10 and reflects the information in the routing. The route quality information table management unit 46 generates and manages a route quality information table based on the result selected by the NextHop processing unit 44. FIG. 7 shows the data structure of the route quality information table managed by the route quality information table management unit 46. As shown in the figure, a destination IP address column 124, an adjacent terminal device IP address column 126, a quality column 128, a hop number column 130, and an update time column 132 are included.

  In the destination IP address column 124, the IP address of the terminal device 10 that is the destination is entered. The destination IP address column 124 corresponds to the transmission destination column 112 in FIG. In the adjacent terminal device IP address column 126, the IP address of the terminal device 10 selected by the NextHop processing unit 44 is entered. In the quality column 128, communication quality is entered. Here, dimensionless values are entered as communication quality values as shown in FIGS. Note that values in the reception level column 118, the packet arrival rate column 120, and the load column 122 in FIG. 5 may be entered. It is assumed that the number of hops is entered in the hop number column 130 and the update time is entered in the update time column 132.

  Next, the processing unit 18 when the terminal device 10 is a transfer terminal device will be described. This corresponds to the case of the second terminal device 10b to the fifth terminal device 10e in FIG. The interface unit 30 receives a packet signal from the terminal device 10 serving as a transfer source. That is, if it is the 2nd terminal device 10b, a packet signal will be received from the 1st terminal device 10a.

  The NextHop processing unit 44 receives a quality request packet signal from another terminal device 10. When receiving the quality request packet signal, the NextHop processing unit 44 notifies the communication quality managed by the route quality information table management unit 46. Since other processes are the same as those in the case where the terminal device 10 is a transmission source terminal device, a description thereof will be omitted.

  The operation of the communication system 100 described above will be described. FIG. 8 is a sequence diagram illustrating a data transfer procedure in the communication system 100. The second terminal apparatus 10b transmits a measurement signal (S10). The third terminal apparatus 10c measures quality (S12). The third terminal apparatus 10c transmits a measurement signal (S14). The fourth terminal apparatus 10d measures quality (S16). The second terminal apparatus 10b transmits a measurement signal (S18). The fourth terminal apparatus 10d measures quality (S20). The third terminal apparatus 10c notifies the measured quality (S22). The second terminal device 10b acquires quality (S24). The fourth terminal apparatus 10d notifies the measured quality (S26).

  The third terminal apparatus 10c acquires quality (S28). The fourth terminal apparatus 10d notifies the measured quality (S30). The second terminal device 10b acquires quality (S32). When the second terminal apparatus 10b detects a transfer instruction (S34), the second terminal apparatus 10b transmits a quality request packet signal (S36). The third terminal apparatus 10c notifies information (S38). When receiving the information (S40), the second terminal device 10b estimates the quality (S42). The second terminal device 10b determines a transfer destination (S44) and transfers data (S46).

  FIG. 9 is a flowchart showing a data transfer procedure by the first terminal apparatus 10a. That is, it is a flowchart showing a data transfer procedure in the transmission terminal device. The transmission detection unit 38 detects a transmission instruction (S60). The route quality examining unit 36 inquires of the NextHop processing unit 44 about a NextHop candidate (S62). If NextHop is the destination terminal device (Y in S64), the route quality examining unit 36 refers to the link quality information table managing unit 34 and acquires the quality (S66). On the other hand, if NextHop is not the destination terminal device (Y in S64), the route quality examining unit 36 transmits a quality request packet signal (S68).

  If the above processing has not been completed for all NextHop candidates (N in S70), the process returns to step 64. If the above processing has been completed for all NextHop candidates (Y in S70), the route quality examining unit 36 receives information (S72). If all the information has not been received (N in S74), the process returns to step 72. If all the information is accepted (Y in S74), the route quality examining unit 36 estimates the quality and then outputs the quality to the NextHop processing unit 44. The NextHop processing unit 44 determines NextHop based on the quality (S76). The NextHop processing unit 44 outputs the selected NextHop to the routing protocol execution unit 42, and the routing table management unit 40 updates the routing table (S78).

  FIG. 10 is a flowchart showing a data transfer procedure by the second terminal apparatus 10b. That is, it is a flowchart showing a data transfer procedure in the transfer terminal device. The interface unit 30 receives the quality request packet signal (S100). The route quality examining unit 36 inquires of the NextHop processing unit 44 about a NextHop candidate (S102). If NextHop is the destination terminal device (Y in S104), the route quality examining unit 36 refers to the link quality information table managing unit 34 and acquires the quality (S106). On the other hand, if NextHop is not the destination terminal device (Y in S104), the route quality examining unit 36 transmits a quality request packet signal (S108).

  If the above processing has not been completed for all NextHop candidates (N in S110), the process returns to step 104. If the above processing has been completed for all NextHop candidates (Y in S110), the route quality examining unit 36 receives information (S112). If all the information has not been received (N in S114), the process returns to step 112. If all the information has been received (Y in S114), the route quality examining unit 36 estimates the quality, and then outputs the quality to the NextHop processing unit 44. The NextHop processing unit 44 determines NextHop based on the quality (S116). The NextHop processing unit 44 outputs the selected NextHop to the routing protocol execution unit 42, and the routing table management unit 40 updates the routing table (S118). The NextHop processing unit 44 transmits information (S120).

  According to the embodiment of the present invention, the communication quality at the time of transferring the packet signal to the adjacent terminal device is estimated while reflecting the information on the communication quality at the time when the adjacent terminal device transfers the packet signal. It is possible to consider the influence of the route ahead from the terminal device. In addition, since the influence of the route ahead from the adjacent terminal device is taken into consideration, a terminal device suitable for transfer can be determined. One terminal device accepts information on the communication quality when an adjacent terminal device transfers a packet signal, and does not accept each communication quality of a plurality of wireless sections from the adjacent terminal device, thus simplifying the processing. However, the influence of the route ahead from the adjacent terminal device can be considered. Further, since the influence of the communication quality up to the destination terminal device is reflected, the accuracy of selection of the terminal device to which the packet signal should be transferred can be improved.

  In addition, since communication quality is acquired at a predetermined timing, it is possible to follow fluctuations in communication quality. In addition, the processing time for determining the transfer destination can be shortened. Further, since the information is not received until the transfer is executed, the processing amount can be reduced. In addition, since the worse communication quality is selected, the bandwidth that can be secured by the transfer can be grasped. In addition, since at least one adjacent terminal device candidate is reduced, the processing can be simplified. In addition, since the estimated communication quality is notified, a value reflecting the communication quality in the previous route can be notified from the terminal device.

  In the above, this invention was demonstrated based on the Example. This embodiment is an exemplification, and it will be understood by those skilled in the art that various modifications can be made to the combination of each component and each processing process, and such modifications are also within the scope of the present invention. .

  In the embodiment of the present invention, the link quality measurement unit 32 uses a measurement signal in order to measure quality. However, the present invention is not limited thereto, and for example, the link quality measurement unit 32 may use a packet signal that is regularly transmitted by the routing protocol. An example of a packet signal that is constantly transmitted is a “Hello message”. The link quality measurement unit 32 may use data when data is transmitted between the terminal devices 10. According to this modification, the number of samples for measuring quality can be increased, and the quality accuracy can be improved. That is, any signal that can measure the communication quality between adjacent terminal apparatuses 10 may be used.

  In the embodiment of the present invention, the NextHop processing unit 44 selects the terminal device 10 based on the communication quality. However, the present invention is not limited to this. For example, if the difference in quality is small, the terminal device 10 that reduces the number of hops may be selected. According to this modification, it is possible to select the terminal device 10 while taking into account a decrease in bandwidth due to an increase in the number of hops. That is, it is only necessary to select the terminal device 10 that increases the substantial bandwidth.

  In the embodiment of the present invention, the route quality examining unit 36 estimates the communication quality when starting to transfer a packet signal. However, the present invention is not limited to this. For example, the route quality examining unit 36 estimates the communication quality while the packet signal is being transferred, and the NextHop processing unit 44 selects the terminal device 10 based on the estimated communication quality. May be switched. According to this modification, it is possible to select a route suitable for data transfer while following changes in the wireless transmission path. That is, it is only necessary to select the terminal device 10 that increases the substantial bandwidth.

  In the embodiment of the present invention, the communication system 100 has been described as a wireless LAN conforming to the IEEE 802.11b standard. However, the present invention is not limited to this. For example, the communication system 100 may be another wireless communication system. For example, a wireless LAN conforming to the IEEE 802.11a standard. According to this modification, the present invention can be applied to various wireless communication systems. That is, any wireless communication system compatible with an ad hoc network may be used.

It is a figure which shows the structure of the communication system which concerns on the Example of this invention. 2A to 2D are diagrams illustrating the operation principle of the communication system of FIG. It is a figure which shows the structure of the 2nd terminal device of FIG. It is a figure which shows the structure of the process part of FIG. It is a figure which shows the data structure of the link quality information table managed in the link quality information table management part of FIG. It is a figure which shows the data structure of the routing table managed in the routing table management part of FIG. FIG. 5 is a diagram illustrating a data structure of a route quality information table managed by a route quality information table management unit in FIG. 4. It is a sequence diagram which shows the transfer procedure of the data in the communication system of FIG. It is a flowchart which shows the transfer procedure of the data by the 1st terminal device of FIG. It is a flowchart which shows the transfer procedure of the data by the 2nd terminal device of FIG.

Explanation of symbols

  10 terminal device, 12 antenna, 14 RF unit, 16 modem unit, 18 processing unit, 20 IF unit, 22 control unit, 30 interface unit, 32 link quality measurement unit, 34 link quality information table management unit, 36 route quality survey unit , 38 transmission detection unit, 40 routing table management unit, 42 routing protocol execution unit, 44 NextHop processing unit, 46 route quality information table management unit, 100 communication system.

Claims (8)

In an ad hoc network that sequentially transfers data by a plurality of wireless devices, an acquisition unit that respectively acquires communication quality between at least one adjacent wireless device;
A receiving unit that receives information on communication quality when each of at least one adjacent wireless device transfers data from each of at least one adjacent wireless device;
Based on the communication quality acquired in the acquisition unit and the information received in the reception unit, for each of at least one adjacent wireless device, an estimation unit for estimating the communication quality when transferring data;
Based on the communication quality estimated by the estimation unit, a selection unit that selects a wireless device to which data is to be transferred;
A wireless device comprising:   The radio apparatus according to claim 1, wherein the information received by the reception unit reflects an influence of communication quality from each of at least one adjacent radio apparatus to a data destination radio apparatus. A detection unit for detecting a data transfer instruction;
The acquisition unit executes acquisition of communication quality at a predetermined timing,
The wireless device according to claim 1, wherein the reception unit executes information reception when the detection unit detects an instruction.   The estimation unit selects data for the wireless device by selecting the worse of communication quality between the adjacent wireless device and communication quality when the wireless device transfers data. The wireless device according to claim 1, wherein communication quality at the time of transfer is estimated, and further, estimation is performed for each of at least one adjacent wireless device. An execution unit for executing a routing protocol for the ad hoc network;
The estimation unit selects, as at least one adjacent wireless device, a wireless device that can transfer data with a predetermined number of hops to a wireless device selected by execution of a routing protocol in the execution unit. The wireless device according to any one of claims 1 to 4. An input unit for inputting a request for transmission of the communication quality estimated in the estimation unit from another wireless device;
2. The information processing apparatus according to claim 1, further comprising: a notification unit configured to notify the communication quality estimated by the estimation unit when the input unit inputs a request and the communication quality for the radio device selected by the selection unit. 6. The wireless device according to any one of 1 to 5. In an ad hoc network, it has a plurality of wireless devices that sequentially transfer data,
Information received from each of at least one adjacent wireless device and information regarding communication quality when each of the adjacent at least one wireless device transfers data and at least one adjacent wireless device The process of selecting a wireless device to which data should be transferred while estimating the communication quality at the time of transferring data for each of at least one adjacent wireless device based on the communication quality of The communication system is sequentially executed from a wireless device close to a data destination wireless device among the devices. In an ad hoc network, a communication method using a plurality of wireless devices that sequentially transfer data,
Information received from each of at least one adjacent wireless device and information regarding communication quality when each of the adjacent at least one wireless device transfers data and at least one adjacent wireless device The process of selecting a wireless device to which data should be transferred while estimating the communication quality at the time of transferring data for each of at least one adjacent wireless device based on the communication quality of The communication method is executed sequentially from a wireless device close to a data destination wireless device of the devices.

Images