JP2006025372A - Communication method, wireless apparatus and communication system utilizing the method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To transfer video information and audio information even if a throughput is low on an ad hoc network. <P>SOLUTION: An input section 50 receives a packet signal which contains video information and audio information, from a predetermined terminal device included in an ad hoc network. A dividing section 68 inputs the packet signal from the input section 50 and divides the inputted packet signal into a plurality of packet signals. In such a case, the dividing section 68 divides the inputted packet signal into the plurality of packet signals so that the video information and the audio information contained in the inputted packet signal at least may be contained in another packet signal. A transmission routing section 62 determines a terminal device to which the packet signals are to be transmitted, respectively based on routing information stored in a routing information holding section 60. An output section 64 outputs the packet signals to the determined terminal device. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a communication technique, and more particularly to a communication method for transmitting video information and audio information in an ad hoc network, and a radio apparatus and a communication system using the communication method.

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. In addition, even a terminal device that cannot communicate directly can perform communication because a signal is relayed by another terminal device (see, for example, Non-Patent Document 1).
Baruch Awerbuch, David Holmer, Herbert Rubens, “High Throughput Route Selection in Multi-Rate Ad Hoc Wireless Network”, First Forest. 251-268, 2004

  Since an ad hoc network does not include a base station device or a switch as in a mobile communication system, control of a signal path to be communicated, that is, control of routing is executed by a terminal device. Therefore, conventionally, a DSDV (Destination Sequential Distance Vector) method or the like is used. In the DSDV system, terminal devices exchange information about terminal devices that can communicate with each other, and a signal arrives at a terminal device to which a signal should be transmitted directly and a destination terminal device to transmit a signal to the destination terminal device. Each terminal device manages information such as the number of terminal devices (hereinafter referred to as “hops”) that are relayed before the combination of terminal devices that are routed to reach (referred to as “route”) . 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 the terminal device that should transmit the direct signal included in the selected route.

  Under such circumstances, the present inventor has come to recognize the following problems. The information transmitted in the ad hoc network is not particularly limited, but may be a stream (hereinafter referred to as “mixed stream”) in which a video stream and an audio stream are mixed as in a telephone conference system. The transmission capacity of such a mixed stream generally tends to increase. On the other hand, in an ad hoc network, as described above, a terminal device to which a signal is to be transmitted is determined by each terminal device. For this reason, since the traffic of the entire network is not adjusted by the exchange or the like, the traffic between predetermined terminal devices may increase. If the mixed stream is transmitted in such a situation, the mixed stream is not transmitted correctly. As a result, both the video stream and the audio stream are interrupted, and the conference call itself cannot be established.

  The present inventor has recognized such a situation and made the present invention, and the purpose thereof is video information and audio information included in a packet signal even when traffic in a part of the ad hoc network is large. And a communication apparatus using the same and a communication system using the same.

  In order to solve the above-described problem, a wireless device according to an aspect of the present invention acquires a reception unit that receives a packet signal from a predetermined wireless device included in an ad hoc network, and acquires information about a plurality of routes in the ad hoc network. A plurality of wireless devices to which the plurality of divided packet signals are to be transmitted based on the acquired information on the plurality of routes of the ad hoc network, and a division unit that divides the received packet signal into a plurality of packet signals. And a transmission unit that transmits a plurality of divided packet signals to the determined plurality of wireless devices. The packet signal received by the receiving unit includes at least video information and audio information. The dividing unit divides the received packet signal into a plurality of packet signals so that at least the video information and the audio information are included in different packet signals.

  “Route information” includes a terminal device that is a signal destination, a terminal device that is to transmit a signal next, the number of hops to the terminal device that is the signal destination, and the like to execute routing control in an ad hoc network This is necessary information. Further, “obtaining information about a route” may be obtained in any form of information about a route.

  According to this aspect, since one packet signal is divided into a plurality of packet signals so that the video information and the audio information are included in different packet signals, the probability that both the video information and the audio information are not transmitted can be reduced.

  The information on the plurality of routes of the ad hoc network acquired by the acquisition unit may include information on throughput for each route. Based on the throughput information, the determination unit determines the throughput of the packet signal including the video information and the packet signal including the audio information among the plurality of divided packet signals for the higher bit rate. Allocate wireless devices corresponding to high paths.

The “throughput” information is not limited to the effective throughput that can be actually achieved, but may be an ideal throughput according to the standard, as long as it is a value that is an indicator of the ability to transmit a signal. . The “bit rate” is the amount or number of bits that should be generated in a predetermined period when video information or audio information is generated or encoded.
According to this modification, a high-throughput route is assigned to the video information and the audio information that require high throughput, so that the possibility that the video information is transmitted can be increased.

  When the dividing unit divides the received packet signal into a plurality of packet signals, the dividing unit generates a time stamp for establishing synchronization of video information and audio information, and adds the generated time stamp to each of the plurality of packet signals. May be. Since the time stamp is added when the packet signal is divided, even when the video information and the audio information are received by different packet signals, the video information and the audio information can be reproduced in synchronization with each other.

  Another aspect of the present invention is a communication system. The communication system includes: a source wireless device that transmits a packet signal to an ad hoc network; a destination wireless device that receives a packet signal from the ad hoc network; and a plurality of paths included in the ad hoc network. A plurality of transfer wireless devices for sequentially transferring packet signals from the transmission source wireless device to the destination wireless device along a path from the transmission source wireless device to the destination wireless device. The transmission-source wireless device transmits at least video information and audio information in the same packet signal, and one of the plurality of transfer wireless devices has at least the video information and audio information included in the same packet signal in different packets. While dividing one packet signal into a plurality of packet signals so as to be included in the signal, a plurality of routes to the destination wireless device are also set, and the transfer wireless devices included in each of the plurality of set routes are set. Then, the plurality of divided packet signals are respectively transferred, and the destination wireless device receives the plurality of packet signals each including the video information and the audio information through the set plurality of routes.

  According to this aspect, one of the plurality of transfer wireless devices divides one packet signal into a plurality of packet signals so that the video information and the audio information are included in different packet signals. Is less likely to be transmitted to the destination wireless device.

  One of the plurality of transfer wireless devices that should divide the packet signal is that the throughput of the route to the destination wireless device is more than the throughput required to transfer at least video information and audio information in the same packet signal. May be determined to be the transfer wireless device that has become lower. It is possible to avoid a risk that a packet signal including video information and audio information is not transmitted.

One of the plurality of transfer wireless devices that should divide the packet signal is that when there are a plurality of routes to the destination wireless device, a route for actually transferring the packet signal among the plurality of routes is determined. May be determined as the transfer wireless device changed at a frequency of Since the packet signal including the video information and the audio information is not transmitted through a path with low stability, the probability that both the video information and the audio information are not transmitted to the destination wireless device can be reduced.

  Yet another embodiment of the present invention is a communication method. The method includes a step in which a source wireless device transmits a packet signal in an ad hoc network, and a step in which a plurality of transfer wireless devices sequentially transfer the packet signal along a predetermined path in the ad hoc network. And a destination wireless device receiving the packet signal in the ad hoc network. The transmitting step includes transmitting at least video information and audio information in the same packet signal, and sequentially transferring the video information and audio information included in at least the same packet signal by one of a plurality of transfer wireless devices. Is divided into a plurality of packet signals so that it is included in another packet signal, and multiple routes to the destination wireless device are also set, and the transfer is included in each of the set multiple routes. The step of transferring and receiving a plurality of divided packet signals to the wireless device receives a plurality of packet signals each including video information and audio information via a plurality of set paths.

  According to this aspect, one of the plurality of transfer wireless devices divides one packet signal into a plurality of packet signals so that the video information and the audio information are included in different packet signals. The probability that both are not transmitted to the destination wireless device can be reduced.

  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, video information and audio information included in a packet signal can be transmitted even when the traffic in a part of the ad hoc network is large.

  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. That is, among a plurality of terminal devices included in an 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 “transfer terminal device”) and received by the terminal device that reproduces 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, the throughput, etc., and updates its own routing information based on the received routing information. To do. When a terminal device receives a packet signal from a predetermined terminal device, the terminal device determines a terminal device to which the packet signal should be transmitted while referring to routing information based on the destination of the signal.

  In this embodiment, the packet signal generated by the transmission source terminal device includes video information and audio information (hereinafter, these information are collectively referred to as “mixed information”). For example, a packet signal in which video information and audio information are integrally encoded by MPEG (Moving Picture Coding Experts Group) or the like is generated (here, information in which video information and audio information are integrally encoded is also “ Mixed information)). The transfer terminal device transfers the packet signal based on the routing information. At this time, if the throughput of the transfer path is larger than the throughput required for transmitting the mixed information, the transfer terminal apparatus transfers the packet signal as it is. On the other hand, if the throughput of the transfer path is smaller than the throughput required to transmit the mixed information, the transfer terminal device decodes the mixed information to acquire video information and audio information, and encodes the video information Packet signal (hereinafter referred to as “video packet signal”) and packet signal obtained by encoding audio information (hereinafter referred to as “audio packet signal”), that is, a plurality of packet signals including video information and audio information separately. (Hereinafter, the terminal device that divides the packet signal among the transfer terminal devices is referred to as a “division terminal device”).

  In general, the throughput required to transmit the video packet signal is larger than the throughput required to transmit the audio signal, that is, the bit rate is large. Therefore, the dividing terminal device is connected to the destination terminal device. Among the plurality of routes, a route with a high throughput is assigned to the video packet signal, and a route with a low throughput is assigned to the audio packet signal. Further, when dividing the mixed information into video information and audio information, the dividing terminal device generates a time stamp for the purpose of establishing synchronization between the mixed information and adds it to the video packet signal and the audio packet signal. The destination terminal signal establishes synchronization with the video packet signal and the audio packet signal received via different paths based on the time stamp, and acquires the video information and the audio information. Play them further. In this way, if the throughput is smaller than the predetermined value, video information and audio information are transmitted by different packet signals, so even if one of the transmissions fails due to an error, the other may be transmitted. One of video or audio can be provided.

  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 IEEE 802.11b standard, and therefore the communication speed is appropriately selected from among 11 Mbps, 5.5 Mbps, 2 Mbps, and 1 Mbps. 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 including mixed information 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. At that time, the dividing terminal device, which is one of the plurality of transfer terminal devices, divides the packet signal including the mixed information into the video packet signal and the audio packet signal, and also sets a plurality of routes to the destination terminal device. Then, the video packet signal and the audio packet signal are respectively transferred to the transfer terminal devices respectively included in the set plural paths. Further, the division terminal device transfers the video packet signal to the transfer terminal device included in the route having a high throughput among the set routes. A method for determining the dividing terminal device from among the transfer terminal devices will be described later.

  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”). Further, since the throughput of the first route and the throughput of the second route are both smaller than the throughput necessary for transmitting the mixed information, the second terminal device 10b corresponds to the “division terminal device”. The mixed information is divided into video information and audio information. Further, since the throughput of the first route is larger than the throughput of the second route, the second terminal apparatus 10b transmits the video packet signal to the first route and transmits the audio packet signal to the second route. When the dividing terminal device divides one packet signal into a video packet signal and an audio packet signal, it generates a time stamp for establishing synchronization of the video information and the audio information, and the generated time stamp is used as the video packet signal. And added to the voice packet signal.

  The destination terminal device receives the video packet signal and the audio packet signal from the ad hoc network through the set paths. That is, the sixth terminal device 10f reproduces video information and audio information.

  Here, as a premise of the present embodiment, it is assumed that the communication system 100 is executing a routing method such as the DSDV method. In other words, each terminal device 10 has a “Destination”, “NextHop (terminal device to which data is to be directly transmitted)”, “Metric (number of hops)”, “Sequence number” with other DSDVs. , “Install” and “Flags” are exchanged. The terminal device 10 updates the latest routing information based on the exchanged routing information. That is, these pieces of information correspond to information related to at least one route of the ad hoc network. Further, information regarding throughput is also exchanged between the terminal devices 10.

  FIG. 2 shows the 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 apparatus 10 supports a plurality of communication speeds, 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 controls processing 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 is realized by a program having a reservation management function loaded in 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.

  FIG. 3 shows the configuration of the processing unit 18. The processing unit 18 includes an input unit 50, a synchronization control unit 52, a decoding unit 54, a media operation unit 56, a throughput acquisition unit 58, a routing information holding unit 60, a transmission route determination unit 62, an output unit 64, and an encoding unit 66. The media operation unit 56 includes a dividing unit 68 and a media converting unit 70, and the media converting unit 70 further includes an encoding method converting unit 72 and a rate changing unit 74. Here, the operation of the components to be related when the terminal device 10 operates as a transfer terminal device, particularly as a division terminal device, will be described.

  The input unit 50 receives a packet signal from a predetermined terminal device 10 included in the ad hoc network. Here, as described above, it is assumed that the packet signal received by the input unit 50 includes at least video information and audio information. The throughput acquisition unit 58 acquires the throughput with another terminal device 10 via the input unit 50. The method for obtaining the throughput may be any method, but is measured by, for example, ping. Also, the throughput with the terminal device 10 capable of communication is acquired. For example, in the case of the second terminal device 10b in FIG. 1, the throughput between the first terminal device 10a, the third terminal device 10c, and the fourth terminal device 10d is acquired. Further, the throughput is measured by a predetermined method, and the throughput information is exchanged between the other terminal apparatus 10 via the input unit 50 and the output unit 64 described later.

  The routing information holding unit 60 acquires information on a plurality of routes in the ad hoc network, that is, routing information. This routing information includes information on the throughput acquired by the throughput acquisition unit 58. FIG. 4 shows an example of the data structure of the routing information stored in the routing information holding unit 60. “Destination” indicates the terminal apparatus 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. “Destination” indicates the terminal apparatus 10 to which the packet signal should be directly transmitted. “Metric” indicates the number of hops to the terminal device 10 corresponding to “destination”. The above is generated by the DSDV method. Further, “effective throughput” is a value acquired by the throughput acquisition unit 58.

  Returning to FIG. When the dividing unit 68 operates as a dividing terminal device, the dividing unit 68 inputs a packet signal from the input unit 50 and divides the input packet signal into a plurality of packet signals. Here, the dividing unit 68 divides the input packet signal into a plurality of packet signals so that at least the video information and audio information included in the input packet signal are included in different packet signals, and the video packet described above is obtained. Generate signal and voice packet signal. Further, when the dividing unit 68 divides the input packet signal into a plurality of packet signals, the dividing unit 68 generates a time stamp for establishing synchronization between the video information and the audio information, and the generated time stamp is used as the video packet signal and the audio. It is added to each packet signal. Here, the dividing unit 68 generates a time stamp as follows. When the transmission source terminal device adds a time stamp to a packet signal including video information and audio information, the time stamp calculated based on the already added time stamp is used as a new time stamp. To do. Alternatively, a time stamp obtained by copying a time stamp that has already been added is set as a new time stamp. On the other hand, when the transmission source terminal device does not add a time stamp to the packet signal including the video information and the audio information, the time stamp is generated based on the time when the packet signal is received.

  The encoding method conversion unit 72 changes the encoding parameters of the encoded information. That is, the packet signal before being divided by the dividing unit 68 includes mixed information, which is information obtained by integrally encoding video information and audio information. In order to divide the mixed information, the encoding method conversion unit 72 decodes the mixed information and extracts video information and audio information. Furthermore, video information and audio information are encoded separately. For example, video information is encoded by MPEG2 and audio information is converted to G.264. 711 for encoding.

  The rate changing unit 74 changes the sampling rate of video information and audio information, the video size, and the like. In other words, since the effective throughput of the path is small, the rate changing unit 74 determines whether the video signal and audio information sampling rate that has been set is difficult to transmit even if the packet signal is divided. The sampling rate of the video information and the audio information is changed so that the bit rate of the information and the audio information becomes a small value. As a result, the quality of video information and audio information may be reduced, but a predetermined route can be transmitted reliably.

  When the transfer terminal device does not operate as a dividing terminal device, that is, when packet signals are transferred, the dividing unit 68 does not operate, but the encoding method converting unit 72 and the rate changing unit 74 operate as described above. To convert the bit rate of the information. For example, when the mixed information encoded by MPEG2 is input, the encoding method conversion unit 72 converts the encoding method of the mixed information into MPEG4. When video information encoded in MPEG2 is input, the encoding method of the video information is converted into MPEG4. In addition, G. When the speech information encoded in 711 is input, the encoding method of the speech information is changed to G.711. 729. In the operations of the dividing unit 68, the encoding method converting unit 72, and the rate changing unit 74, it is assumed that the routing information stored in the routing information holding unit 60 is appropriately used by signals not shown.

  Based on the routing information stored in the routing information holding unit 60, the transmission route determination unit 62 determines the terminal devices 10 that are to transmit packet signals, and are included in a predetermined route. In the case of the dividing terminal device, a plurality of terminal devices 10 to which video packet signals and audio packet signals are to be transmitted are determined. At that time, the transmission route determination unit 62 assigns the terminal device 10 corresponding to the route having a higher throughput than the audio packet signal to the video packet signal based on the throughput information in the routing information. For example, in FIG. 1, the third terminal apparatus 10c is determined as the transmission destination of the video packet signal, and the fourth terminal apparatus 10d is determined as the transmission destination of the audio packet signal.

  The output unit 64 outputs a packet signal to the determined terminal device 10. In the case of the dividing terminal device, the video packet signal and the audio packet signal are respectively output to the determined terminal devices 10.

  Next, when the terminal device 10 operates as a transmission source terminal device, an operation of a component to be related will be described. The encoding unit 66 is connected to an external camera and microphone (not shown), and inputs video information and audio information via the camera and microphone, respectively. Furthermore, video information and audio information are integrally encoded by MPEG or the like to generate mixed information. At that time, a time stamp is also added. Note that the encoding unit 66 is connected to a video playback device or the like instead of an external camera or microphone, and inputs integral information of video information and audio information via the video playback device, and encodes the information. To generate mixed information. The generated mixed information is output via the transmission route determination unit 62 and the output unit 64. The operations of the transmission route determination unit 62 and the output unit 64 are as described above.

  Furthermore, when the terminal device 10 operates as a destination terminal device, operations of components that should be related will be described. The synchronization controller 52 extracts time stamps from the input video packet signal and audio packet signal, respectively, and based on the extracted time stamp, the video packet signal and audio packet signal, that is, encoded video information and audio information Synchronization (hereinafter referred to as “intermediate synchronization”). Also, video packet signals and audio packet signals are rearranged at equal intervals based on the extracted time stamps, and synchronization between the encoded video information and audio information (hereinafter referred to as “in-media synchronization”) is also established. To do. As described above, the time stamp extracted from the input video packet signal and audio packet signal is used to perform synchronization within the medium and synchronization between the media. Since the synchronization establishment method based on the time stamp may be performed by a conventional technique, description thereof is omitted. The decoding unit 54 decodes the encoded video information and audio information, respectively, and acquires the video information and audio information. Furthermore, the video information and audio information are output to an external display and speaker (not shown) and reproduced.

  FIG. 5 is a flowchart showing a processing procedure in the first terminal apparatus 10a, that is, the transmission source terminal apparatus. The encoding unit 66 inputs audio information and video information from the outside (S10). Further, after adding the time stamp (S12), the encoding unit 66 integrally encodes the audio information and the video information (S14) to generate mixed information. The transmission route determining unit 62 refers to the routing information stored in the routing information holding unit 60 and determines a transmission route to which a packet signal including mixed information should be transmitted (S16). In particular, transmission to the terminal device 10 included in the transmission route is determined. The output unit 64 transmits a packet signal via the modem unit 16 and the RF unit 14 (S18).

  FIG. 6 is a flowchart showing a processing procedure in the second terminal device 10b to the fifth terminal device 10e, that is, the transfer terminal device. Here, the transfer terminal device includes a division terminal device.

  The input unit 50 inputs a packet signal via the RF unit 14 and the modem unit 16 (S20). If the media operation unit 56 determines that the input packet signal is a packet signal in which audio information and video information are integrated (Y in S22) and needs to be divided from the information of effective throughput (Y in S24). The dividing unit 68 divides the mixed information included in the packet signal into audio information and video information. Further, the media conversion is executed as required by the encoding method conversion unit 72 and the rate change unit 74 (S26). Through the above operation, an audio packet signal and a video packet signal are generated. Here, the media conversion includes the above-described encoding method conversion and sampling rate conversion, and is executed when the throughput is insufficient. As described above, a time stamp is also generated at the time of division.

  On the other hand, when the input packet signal is not a packet signal in which audio information and video information are integrated (N in S22), the media operation unit 56 is a packet signal in which audio information and video information are integrated (S22). If it is determined that no division is necessary (N in S24), the necessity of media conversion is confirmed based on the effective throughput information. If media conversion is necessary (Y in S28), the media conversion is executed by the encoding method conversion unit 72 and the rate change unit 74 (S30). If media conversion is not necessary (N in S28), media conversion is not executed. The transmission route determining unit 62 refers to the routing information stored in the routing information holding unit 60 and determines a transmission route to which the packet signal should be transmitted (S32). In particular, transmission to the terminal device 10 included in the transmission route is determined. When an audio packet signal and a video packet signal are generated, transmission to a plurality of terminal devices 10 is determined. The output unit 64 transmits a packet signal via the modem unit 16 and the RF unit 14 (S34).

  FIG. 7 is a flowchart of a time stamp generation procedure performed in the packet division process of FIG. If a time stamp is added to the audio / video packet signal in the transmission source terminal device (Y in S50), the dividing unit 68 copies a time stamp that has already been added or a time stamp that has already been added. The time stamp calculated based on the new time stamp is set as a new time stamp (S52). On the other hand, if a time stamp is not added to the audio / video packet signal in the terminal device for transmission (N in S50), the dividing unit 68 generates a time stamp based on the time when the audio / video packet signal is received. (S54). Further, the generated time stamp is added to the audio packet signal and the video packet signal (S56).

  FIG. 8 is a flowchart showing a processing procedure in the sixth terminal device 10f, that is, the destination terminal device. The input unit 50 inputs an audio packet signal and a video packet signal via the RF unit 14 and the modem unit 16 (S40). The synchronization control unit 52 includes the audio information and video information included in the audio packet signal and the video packet signal, and encoded audio based on the time stamps added to the audio packet signal and the video packet signal, respectively. Timing synchronization control is executed between the information and the video information (S42). The timing synchronization control includes the above-described inter-media synchronization and intra-media synchronization. The decoding unit 54 decodes the encoded audio information and video information (S44). Further, the decoded audio information and video information are output (S46). Note that the timing control may be performed between the audio information and the video information after the encoded audio information and the video information are decoded by reversing the processes of the synchronization control unit 52 and the decoding unit 54.

  Here, a method for determining one terminal device 10 as a dividing terminal device from among the plurality of terminal devices 10 included in the ad hoc network will be described. Here, the case where the said determination is made by two types of terminal devices 10 is demonstrated. One is a case where the terminal device 10 that should be the terminal device for division executes the determination itself. For example, in FIG. 1, among the second terminal device 10b to the fifth terminal device 10e, the second terminal device 10b decides by itself that it will become a dividing terminal device. At that time, the terminal device 10 that has decided to become the dividing terminal device may notify the other terminal devices 10 of the fact. As a result, it is possible to prevent another terminal device 10 from becoming a dividing terminal device.

  The other is a case where the terminal device for transmission determines the terminal device 10 that should be the terminal device for division. For example, in FIG. 1, the first terminal device 10a determines that the second terminal device 10b among the second terminal devices 10b to 5e is the dividing terminal device. In this case, information necessary for the transmission source terminal device to determine the dividing terminal device is notified from a plurality of transfer terminal devices. This will be described later.

  In addition, an index to be used when determining one terminal apparatus 10 as a terminal apparatus for division will be described. Here, two types of indices will be described. One is an index based on effective throughput. That is, the plurality of terminal devices 10 perform a comparison between the throughput of the route to the destination terminal device and the throughput necessary for transferring the mixed signal in the packet signal. The terminal device 10 in which the former is lower than the latter is determined to be the dividing terminal device. In FIG. 1, in the second terminal apparatus 10b, the throughput of the path from the second terminal apparatus 10b to the third terminal apparatus 10c and the throughput of the path from the second terminal apparatus 10b to the fourth terminal apparatus 10d are mixed signals. The throughput is lower than that required to transfer the packet signal.

  The other is an index based on the degree to which the terminal device 10 that should transmit the packet signal is changed. That is, when there are a plurality of routes from the terminal device 10 to the destination terminal device, the terminal device 10 that changes the route for actually transferring the packet signal among the plurality of routes at a predetermined frequency is used for the division. It is determined that it should be a terminal device. This will be described with reference to FIG. FIG. 9 is a diagram illustrating a concept of a method for determining a terminal device for division in the communication system 100.

  The communication system 100 of FIG. 9 adds the 7th terminal device 10g and the 8th terminal device 10h to the communication system 100 of FIG. Here, a solid line indicates a route selected at a predetermined timing, and is a route from the first terminal device 10a to the sixth terminal device 10f via the second terminal device 10b and the third terminal device 10c. In addition, a route selected at a timing different from the timing at which the solid line is selected is selected as the dotted line. The transfer terminal devices that have fixedly selected one route are the third terminal device 10c, the fourth terminal device 10d, and the eighth terminal device 10h. On the other hand, the terminal devices for transfer that switch any one of the plurality of routes at a predetermined interval are the second terminal device 10b and the seventh terminal device 10g. For example, the second terminal device 10b switches any of the third terminal device 10c, the fourth terminal device 10d, and the seventh terminal device 10g as a route at a predetermined interval.

  Further, the seventh terminal device 10g switches either the fifth terminal device 10e or the eighth terminal device 10h as a route at a predetermined interval. As described above, the routes are switched at a predetermined interval because the throughput of those routes is not stable, that is, the throughput may be lowered. Therefore, a signal is directly transmitted to such a route. The terminal device 10 to be determined is determined to be the dividing terminal device. In FIG. 9, among the second terminal device 10b and the seventh terminal device 10g, the second terminal device 10b closer to the transmission source terminal device is determined as the dividing terminal device. If the second terminal apparatus 10b has already divided into a video packet signal and an audio packet signal, the throughput required for transmitting the packet signal at the seventh terminal apparatus 10g is low, and there is no need to switch the route. Because there is.

  FIG. 10 is a sequence diagram illustrating a procedure for generating routing information in the communication system 100. As described above, this is a procedure executed to notify the transmission source terminal device of predetermined information when the transmission source terminal device determines the terminal device 10 to be the division terminal device. Further, in order to determine the terminal device 10 that should be the terminal device for division, either an index based on the effective throughput or an index based on the extent to which the terminal device 10 that should transmit the packet signal is changed is executed. For this reason, effective throughput is notified as predetermined information in the former case, and change information is notified in the latter case. It is assumed that the first terminal device 10a to the sixth terminal device 10f in FIG. 1 have already acquired predetermined information regarding the terminal device 10 of itself.

  Here, a process will be described in which the first terminal device 10a collects information acquired by the sixth terminal device 10f from the second terminal device 10b. The first terminal apparatus 10a transmits a request signal to the second terminal apparatus 10b (S100). The second terminal device 10b transmits a request signal to the third terminal device 10c (S102), and the third terminal device 10c transmits a request signal to the sixth terminal device 10f (S104). The second terminal device 10b transmits a request signal to the fourth terminal device 10d (S106), and the fourth terminal device 10d transmits a request signal to the fifth terminal device 10e (S108). 10e transmits a request signal to the sixth terminal apparatus 10f (S110).

  The sixth terminal device 10f notifies the third terminal device 10c of information (S112), and the third terminal device 10c adds its own information to the received information and notifies the second terminal device 10b (S114). The sixth terminal device 10f notifies the fifth terminal device 10e of information (S116), and the fifth terminal device 10e adds its own information to the received information and notifies the fourth terminal device 10d (S118). The fourth terminal apparatus 10d adds its own information to the received information and notifies the second terminal apparatus 10b (S120). Finally, the second terminal apparatus 10b adds its own information to the received information and notifies the first terminal apparatus 10a (S122). The first terminal apparatus 10a determines a dividing terminal apparatus based on the information acquired in this way. Unlike the above description, the second terminal device 10b to the sixth terminal device 10f may notify the first terminal device 10a of information acquired spontaneously.

  According to the embodiment of the present invention, since one packet signal is divided into a video packet signal and an audio packet signal so that the video information and the audio information are included in different packet signals, both the video information and the audio information are The probability of not being transmitted can be lowered. Further, since at least one of video information and audio information is transmitted, some information can be transmitted even when an application such as a video conference is executed. In addition, since a high-throughput route is assigned to video information that requires high throughput, the possibility of video information being transmitted increases. In addition, since the terminal device that should correspond to the dividing terminal device is determined to be the dividing terminal device, the processing can be simplified. In addition, since the transmission source terminal device determines that it will be a dividing terminal device, the processing can be performed with high accuracy.

Further, since the time stamp is added when the packet signal is divided into the video packet signal and the audio packet signal, the video information and the audio information can be reproduced in synchronization with each other. In addition, since the sampling rate and encoding method of video information and audio information can be changed, packet signals suitable for various throughputs of the path can be generated together with packet signal division. Further, since the dividing terminal device is determined based on the throughput, it is possible to avoid the risk that the packet signal including the mixed information will not be transmitted. In addition, since the packet signal including the mixed information is not transmitted through a path with low stability, the probability that both video information and audio information are not transmitted to the destination terminal device can be reduced. Even if the traffic in a part of the ad hoc network is large, video information and audio information included in the packet signal can be transmitted, and high-quality information can be output by the destination 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 terminal device 10 corresponding to the transfer terminal device determines the terminal device 10 to which the packet signal is to be transmitted based on the routing information stored in the routing information holding unit 60. That is, table-driven routing has been executed. However, the present invention is not limited to this, for example, so-called source routing in which the source terminal device determines the route of the packet signal and the transfer terminal device included in the route relays the packet signal as determined. Good. In that case, the routing information acquired by each terminal device 10 is added to the predetermined information transmitted in the sequence diagram shown in FIG. 10, and the information is transmitted to the first terminal device 10a that is the transmission source terminal device. The According to this modification, the present invention can also be applied to source routing. In addition, since information necessary for determination when the terminal device for transmission source determines the terminal device 10 to be a terminal device for division and routing information can be collectively transmitted to the terminal device for transmission source, transmission efficiency can be improved. . That is, the packet signal may be divided when the throughput necessary for transmitting the mixed information is insufficient.

  In the embodiment of the present invention, the terminal device 10 corresponding to the dividing terminal device divides the packet signal into a video packet signal and an audio packet signal. However, the present invention is not limited to this. For example, other information may be included in the division target. For example, the terminal device 10 which is data information and corresponds to the dividing terminal device may generate a packet signal including the data information by dividing the packet signal, or the data information may be generated as a video packet signal or an audio packet. It may be added to the signal. According to this modification, data information can be transmitted in addition to video information and audio information. That is, video information and audio information may be divided so as to be included in different packet signals.

  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.

  In the embodiment of the present invention, in the communication system 100, the bit rate of the video packet signal is greater than the bit rate of the audio packet signal. However, the present invention is not limited to this. For example, the bit rate of the audio packet signal may be larger than the bit rate of the video packet signal. In this case, the transmission route determination unit 62 assigns the terminal device 10 corresponding to a route having a higher throughput than the video packet signal to the audio packet signal based on the throughput information in the routing information. For example, in FIG. 1, the third terminal apparatus 10c is determined as the transmission destination of the audio packet signal, and the fourth terminal apparatus 10d is determined as the transmission destination of the video packet signal. According to this modification, the voice packet signal can be transmitted even when the bit rate of the voice packet signal is high. That is, a route with a high throughput may be assigned to the higher bit rate of the video packet signal and the audio packet signal.

It is a figure which shows the structure of the communication system which concerns on the Example of this invention. 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 an example of the data structure of the routing information memorize | stored in the routing information holding | maintenance part of FIG. It is a flowchart which shows the process sequence in the 1st terminal device of FIG. It is a flowchart which shows the process sequence in the 5th terminal device from the 2nd terminal device of FIG. 7 is a flowchart of a time stamp generation procedure performed in the packet division process of FIG. 6. It is a flowchart which shows the process sequence in the 6th terminal device of FIG. It is a figure which shows the concept of the method of determining the terminal device for a division | segmentation in the communication system of FIG. It is a sequence diagram which shows the production | generation procedure of routing information in the communication system of FIG.

Explanation of symbols

  10 terminal devices, 12 antennas, 14 RF units, 16 modulation / demodulation units, 18 processing units, 20 IF units, 22 control units, 50 input units, 52 synchronization control units, 54 decoding units, 56 media operation units, 58 throughput acquisition units, 60 routing information holding unit, 62 transmission route determining unit, 64 output unit, 66 encoding unit, 68 dividing unit, 70 media converting unit, 72 encoding method converting unit, 74 rate changing unit, 100 communication system.

Claims (9)

A receiving unit that receives a packet signal from a predetermined wireless device included in the ad hoc network;
An acquisition unit for acquiring information on a plurality of routes of the ad hoc network;
A dividing unit for dividing the received packet signal into a plurality of packet signals;
A determination unit configured to determine a plurality of wireless devices to which the plurality of divided packet signals are to be transmitted based on the acquired information about the plurality of routes of the ad hoc network;
A transmitter that transmits the plurality of divided packet signals, respectively, to the determined plurality of wireless devices;
The packet signal received by the receiving unit includes at least video information and audio information,
The wireless device according to claim 1, wherein the dividing unit divides the plurality of packet signals so that at least video information and audio information included in the received packet signal are included in different packet signals. The information on the plurality of routes of the ad hoc network acquired by the acquisition unit includes information on throughput for each route,
Based on the throughput information, the determining unit determines whether the packet signal including video information and the packet signal including audio information among the plurality of divided packet signals has a higher bit rate. 2. The wireless device according to claim 1, wherein a wireless device corresponding to a route with high throughput is assigned.   The dividing unit generates a time stamp for establishing synchronization of video information and audio information when dividing the received packet signal into a plurality of packet signals, and the generated time stamp is converted into the plurality of packet signals. The wireless device according to claim 1, wherein each of the wireless devices is added. A transmission source wireless device that transmits a packet signal to an ad hoc network;
A destination wireless device that receives a packet signal from the ad hoc network;
Packet signals are sequentially transferred from the source wireless device to the destination wireless device along a route from the source wireless device to the destination wireless device among a plurality of routes included in the ad hoc network. Comprising a plurality of wireless transfer devices,
The transmission source wireless device transmits at least video information and audio information in the same packet signal,
One of the plurality of transfer wireless devices divides one packet signal into a plurality of packet signals so that at least video information and audio information included in the same packet signal are included in different packet signals, and the destination Set a plurality of routes to the wireless device for transfer, and transfer each of the divided packet signals to the wireless devices for transfer included in the set routes,
The destination wireless device receives a plurality of packet signals each including video information and audio information via a plurality of set paths.   One of the plurality of transfer wireless devices that should divide the packet signal is that the throughput of the route to the destination wireless device is necessary to transfer at least video information and audio information in the same packet signal. The communication system according to claim 4, wherein the wireless communication device is determined to be a transfer wireless device having a lower throughput.   One of the plurality of transfer wireless devices that should divide the packet signal is a route for actually transferring the packet signal among the plurality of routes when there are a plurality of routes to the destination wireless device. The communication system according to claim 4, wherein the transfer wireless device is determined at a predetermined frequency.   One of the plurality of transfer wireless devices to divide the packet signal is a packet including video information for the transfer wireless device included in the route having a high throughput among the plurality of set routes. The communication system according to any one of claims 4 to 6, wherein a higher bit rate of the signal and the packet signal including voice information is transferred.   One of the plurality of transfer wireless devices that should divide a packet signal generates a time stamp for establishing synchronization of video information and audio information when dividing one packet signal into a plurality of packet signals. The communication system according to claim 4, wherein the generated time stamp is added to each of a plurality of divided packet signals. In the ad hoc network, the transmission source wireless device transmits a packet signal;
A plurality of transfer wireless devices sequentially transferring packet signals along a predetermined route in the ad hoc network; and
Receiving a packet signal in a destination wireless device in an ad hoc network,
The transmitting step includes transmitting at least video information and audio information in the same packet signal,
The step of sequentially transferring comprises transmitting one packet signal to a plurality of packet signals by one of the plurality of transfer wireless devices so that at least video information and audio information included in the same packet signal are included in different packet signals. A plurality of routes to the destination wireless device are set, and a plurality of divided packet signals are respectively transferred to the wireless transfer devices included in the set plurality of routes,
The receiving step receives a plurality of packet signals each including video information and audio information via a plurality of set paths.

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