JP5194303B2 - Wireless device and wireless network provided with the same - Google Patents

Description

  The present invention relates to a wireless device and a wireless network including the wireless device, and more particularly to a wireless device that periodically transmits and receives packets and a wireless network including the wireless device.

  Conventionally, a packet is retransmitted in broadcast in order to increase reliability in the broadcast of the packet (Non-patent Document 1).

  Conventionally, a plurality of packets are network-coded and transmitted in order to reduce the number of packet transmissions (Non-patent Document 2).

  Further, conventionally, a plurality of packets are network-coded and the network-coded packets are broadcast (Non-patent Document 3).

Furthermore, conventionally, a packet including one or more pieces of data is transmitted a plurality of times in order to suppress data loss (Patent Document 1).
JP 2005-123791 A S. Itaya, J. Hasegawa, Y. Kondo, P. Davis, R. Suzuki, and S. Obana, “Demonstration of Robust Multi-hop wireless packet broadcasts for moving vehicles using aggregated redundancy,” Proc. Of LCN, pp. 620-624, Oct. 2007. PA Chou, Y. Wu, and K. Jain, “Practical network coding,” Proc. Of 41st Annual Allerton Conference on Communication, Control and Computing, October 2003. C. Fragouli, J. Widmer, and JY LeBoudec, “Efficient Broadcasting using Network Coding,” IEEE / ACM Transaction on Networking, vol. 16, no. 2, pp. 450-463, April 2008.

  However, even if packets are transmitted using various conventional methods, there is a problem that the packet arrival rate at the transmission destination is low or the packets do not reach immediately. This problem becomes a significant problem when a competitive game is played using ad hoc wireless communication by a portable game machine. In addition, there is a problem that efficient error correction is difficult in an environment where link quality dynamically changes.

  Accordingly, the present invention has been made to solve such a problem, and an object of the present invention is to provide a radio apparatus capable of improving the arrival rate of packets while maintaining the immediacy of arrival of packets to a transmission destination. It is.

  Another object of the present invention is to provide a radio apparatus capable of efficient error correction in an environment where link quality dynamically changes.

  Furthermore, another object of the present invention is to provide a wireless network including a wireless device capable of improving the arrival rate of packets while maintaining immediacy of arrival of packets to a transmission destination.

  Furthermore, another object of the present invention is to provide a wireless network including a wireless device capable of efficient error correction in an environment where link quality dynamically varies.

  According to the present invention, the wireless device is a wireless device that constitutes a wireless network that periodically transmits and receives packets, and includes a reception unit, a coding unit, a packet generation unit, and a transmission unit. The receiving means includes n (n is an integer satisfying 1 ≦ n ≦ N−1) N out of N−1 wireless devices constituting the wireless network (N is an integer of 2 or more). The packet is received in the kth (k is a positive integer) period. The coding means performs network coding on the n packets received by the receiving means using a randomly generated random code string. The packet generation means periodically generates a spontaneous packet for transmission. The transmitting means includes a coding packet network-coded in the (k + 1) th period by the coding means, a spontaneous packet generated in the (k + 1) th period by the packet generating means, and decoding information for decoding the coding packet. A combined packet is generated, and the generated combined packet is broadcast in the (k + 1) th period.

  Preferably, the wireless device further includes decoding means. The decoding unit receives the combined packet broadcast from another wireless device from the receiving unit, extracts decoding information and a coding packet from the received combined packet, and decodes the coding packet using the extracted decoding information.

  Preferably, the coding means generates a code vector composed of N codes constituting a random code string, and also includes a packet composed of N−1 packets and spontaneous packets transmitted from N−1 wireless devices. A matrix is generated, and at least one of the generated code vector and packet matrix, network coding is performed by setting an element corresponding to a packet not received by the receiving means to zero and multiplying the code vector by the packet matrix . The transmission means generates and broadcasts a combined packet including decoding information composed of code vectors. The decoding means extracts decoding information consisting of code vectors and a coding packet from the combined packet, and decodes the coding packet using the extracted code vector.

  Preferably, the coding means generates a code vector composed of N codes constituting a random code string, and also includes a packet composed of N−1 packets and spontaneous packets transmitted from N−1 wireless devices. A matrix is generated, and at least one of the generated code vector and packet matrix, network coding is performed by setting an element corresponding to a packet not received by the receiving means to zero and multiplying the code vector by the packet matrix . The transmission unit generates and broadcasts a combined packet including decode information including a bit string indicating whether or not the reception unit has actually received N−1 packets transmitted from N−1 wireless devices. The decoding means takes out decoding information consisting of a bit string and a coding packet from the combined packet, multiplies the extracted bit string and a random code string held in advance to obtain a code vector, and uses the obtained code vector Decode the coding packet.

  Preferably, the packet generation means generates a first spontaneous packet in the kth cycle and generates a second spontaneous packet in the k + 1th cycle. The transmission means generates a combined packet including a coding packet network-coded in the (k + 1) -th cycle by the coding means, first and second spontaneous packets, and decode information by the packet generation means, and the generated combination The packet is broadcast in the (k + 1) th period.

  According to the present invention, the wireless network is a wireless network in which packets are periodically transmitted and received, and includes N (N is an integer of 2 or more) wireless devices. The N radio devices include first and second radio devices. The first wireless device receives n (n is an integer satisfying 1 ≦ n ≦ N−1) packets from N−1 wireless devices in the k th (k is a positive integer) period, The received n packets are subjected to network coding in the (k + 1) th period using a randomly generated random code sequence, and a spontaneous packet to be transmitted in the (k + 1) th period is generated and the network coded coding is performed. A combined packet including a packet, a spontaneous packet, and decode information for decoding the coding packet is generated, and the generated combined packet is broadcast in the (k + 1) th period. The second wireless device receives the combined packet broadcast from the first wireless device, extracts the spontaneous packet, the coding packet, and the decoding information from the received combined packet, and uses the extracted decoding information to encode the coding packet. Decode.

  Preferably, the first radio apparatus generates a code vector composed of N codes constituting a random code string, and N-1 packets and spontaneous packets transmitted from N-1 radio apparatuses, And at least one of the generated code vector and packet matrix, the element corresponding to the packet not received by the receiving means is set to zero and the code vector is multiplied by the packet matrix In addition to network coding, a combined packet including the network-coded coding packet, decoding information including a code vector, and a spontaneous packet is generated and broadcast in the (k + 1) th period. The second radio apparatus extracts the decoding information including the code vector, the coding packet, and the spontaneous packet from the combined packet, and decodes the coding packet using the extracted code vector.

  Preferably, the first radio apparatus generates a code vector composed of N codes constituting a random code string, and N-1 packets and spontaneous packets transmitted from N-1 radio apparatuses, And at least one of the generated code vector and packet matrix, the element corresponding to the packet not received by the receiving means is set to zero and the code vector is multiplied by the packet matrix A network-coded coding packet, decode information including a bit string indicating whether or not N-1 packets transmitted from N-1 wireless devices are actually received, a spontaneous packet, In the k + 1-th cycle To strike. The second wireless device extracts the decoding information consisting of a bit string, the coding packet, and the spontaneous packet from the combined packet, and multiplies the extracted bit string and a previously stored random code string to obtain a code vector, The coding packet is decoded using the obtained code vector.

  Preferably, the first radio apparatus generates first and second spontaneous packets in the kth cycle and the (k + 1) th cycle, respectively, and the generated first and second spontaneous packets, and (k + 1) th A combined packet including a network-coded coding packet and decode information is generated in the th period, and the generated combined packet is broadcast in the (k + 1) th period. The second wireless device receives the combined packet broadcast from the first wireless device, extracts the first and second spontaneous packets, the coding packet, and the decode information from the received combined packet, and decodes the extracted The coding packet is decoded using the information.

  In the present invention, each wireless device generates a coding packet by network-coding n packets received from other wireless devices in the kth period, and the generated coding packet and the (k + 1) th period A combined packet including a spontaneous packet to be transmitted at is generated in the (k + 1) -th cycle, and the generated combined packet is broadcast. Each wireless device then decodes the coding packet received from the other wireless device in the (k + 1) th cycle, and acquires a packet transmitted from the other wireless device in the kth cycle. As a result, each wireless device can receive a packet that could not be received in the (k + 1) th cycle even if the packet has not been received from another wireless device in the kth cycle.

  Therefore, according to this invention, the packet arrival rate to each transmission destination can be improved. Further, since the packet in the kth cycle is received in the (k + 1) th cycle, the arrival delay of the packet is about one cycle, and immediacy can be maintained.

  Embodiments of the present invention will be described in detail with reference to the drawings. In the drawings, the same or corresponding parts are denoted by the same reference numerals and description thereof will not be repeated.

  FIG. 1 is a schematic diagram of a wireless network according to an embodiment of the present invention. A wireless network 10 according to an embodiment of the present invention includes wireless devices 1 to 6.

  Each of the wireless devices 1 to 6 includes a portable game machine, for example. The wireless devices 1 to 6 are arranged in a wireless communication space and autonomously configure the wireless network 10. And the radio | wireless apparatuses 1-6 transmit / receive a packet regularly mutually, and run a battle | competition type game.

  The necessary performance in this competitive game is, for example, that each of the wireless devices 1 to 6 transmits / receives a packet to / from each of the other five wireless devices, the frame rate is 60 fps, and the packet generation cycle is It is 16.7 ms, the packet size is 50 to 200 bytes, the allowable delay is 50 ms, and the packet arrival rate is 99% or more among the farthest wireless devices.

  When the wireless devices 1 to 6 execute a battle-type game, it is difficult to execute the battle-type game unless each of the wireless devices 1 to 6 receives a packet from another wireless device. For example, when the wireless device 1 cannot receive a packet from the wireless device 5 due to the wireless communication environment, it is impossible to execute a battle-type game between the wireless device 1 and the wireless device 5.

  In the following, a packet transmission method for improving the arrival rate of packets from each of the wireless devices 1 to 6 to each of the other five wireless devices in the wireless network 10 will be described. That is, a packet transmission method for improving the packet arrival rate in many-to-many wireless communication will be described.

[Embodiment 1]
FIG. 2 is a schematic block diagram showing a configuration of the wireless device 1 shown in FIG. 1 in the first embodiment.

  The wireless device 1 includes a reception unit 11, a control unit 12, a decoding unit 13, a buffer 14, a reproduction unit 15, a packet generation unit 16, a coding unit 17, and a transmission unit 18.

  The receiving unit 11 receives a packet PKT composed of a single packet from another wireless device, and outputs the received packet PKT to the control unit 12. Further, the receiving means 11 is a combined packet including a coding packet network-coded in another wireless device, a spontaneous packet generated by the other wireless device, and decoding information for decoding the coding packet by a method described later. PKT_CB is received from another wireless device, and the received combined packet PKT_CB is output to the control means 12.

  When receiving the packet PKT from the receiving means 11, the control means 12 confirms the destination of the received packet PKT. Then, the control unit 12 outputs the packet PKT to the reproducing unit 15 when the destination of the packet PKT is an address of the wireless device 1, and outputs the packet PKT to the reproducing unit 15 when the destination of the packet PKT is a broadcast address. At the same time, the packet PKT is stored in the buffer 14.

  In addition, when receiving the combined packet PKT_CB from the receiving unit 11, the control unit 12 outputs the received combined packet PKT_CB to the decoding unit 13.

  When receiving the combined packet PKT_CB from the control unit 12, the decoding unit 13 decodes the received combined packet PKT_CB by a method described later, and outputs the decoded packet to the reproduction unit 15.

  The buffer 14 holds the packet PKT stored by the control unit 12, the packet PKT stored by the packet generation unit 16, and the coding packet and decoding information stored by the coding unit 17.

  The reproducing unit 15 receives a packet from the control unit 12 or the decoding unit 13 and reproduces the data of the received packet. Then, the reproducing means 15 gives the reproduced data to the operator of the wireless device 1 as visual information by a display means (not shown).

  The packet generation means 16 has a built-in timer (not shown), and refers to the timer to generate a spontaneous packet PKT_Self for broadcasting to other wireless devices every cycle T = 16.7 [ms]. . Then, the packet generator 16 stores the generated spontaneous packet PKT_Self in the buffer 14 and outputs it to the transmitter 18.

  The coding means 17 has a built-in timer (not shown) synchronized with the timer built in the packet generating means 16, and refers to the built-in timer, and a method described later on the packet stored in the buffer 14. Thus, network coding is performed for each period T, and the network-coded coding packet PKT_cd and decoding information for decoding the coding packet PKT_cd are stored in the buffer 14 and output to the transmission means 18.

  The transmission unit 18 includes a timer that is synchronized with the timer that is built in the packet generation unit 16 and the timer that is built in the coding unit 17. Then, when the transmission means 18 receives the spontaneous packet PKT_Self from the packet generation means 16 and receives the coding packet PKT_cd and the decoding information from the coding means 17, the transmission means 18 refers to the timer to obtain the spontaneous packet PKT_Self, the coding packet PKT_cd and the decoding information. The generated combined packet PKT_CB is generated every period T, and the generated combined packet PKT_CB is broadcast.

  Note that each of the wireless devices 2 to 6 illustrated in FIG. 1 has the same configuration as the configuration of the wireless device 2 illustrated in FIG. 2.

Next, a network coding method will be described. Note that the buffer 14 of each of the wireless devices 1 to 6 is configured such that, when the wireless network 10 is configured by N (N is an integer of 2 or more) wireless devices, the receiving unit 11 is connected to other N−1 wireless devices. N + 1 packets P _{1 to} P _{n + 1 of the} received n (n is an integer satisfying 1 ≦ n ≦ N−1) number of packets P _{1 to} P _n and the spontaneous packet PKT_Self stored by the packet generation unit 16 Is stored. In this case, each of the _{n + 1} packets P _{1 to} P _{n + 1} includes a single packet PKT.

The coding means 17 of each of the wireless devices 1 to 6 takes out _{n + 1} packets P _{1 to} P _{n + 1} stored in the buffer 14, and based on the taken out n + 1 packets P _{1 to} P _{n + 1} , packet <P> = (P ₁ , P ₂ ,..., P _N ) is generated. In the embodiment of the present invention, the notation <X> represents a matrix X or a vector X.

When n = N−1, each of the _N−1 packets P _{1 to} P _N−1 is a packet actually received by the receiving unit 11 from the other N−1 wireless devices. On the other hand, when n <N−1, among the _N−1 packets P _{1 to} P _N−1 , each of the _n packets P _{1 to} P _n is actually transmitted from the other wireless devices by the receiving unit 11. Of the N−1 packets P _{1 to} P _N−1 , each of the N−1−n packets includes “0”.

  In the wireless network 10, the wireless devices 1 to 6 transmit and receive packets to each other. Therefore, the coding unit 17 of each wireless device 1 to 6 knows the number N of wireless devices constituting the wireless network 10, It is known that in each cycle T, the maximum number of packets stored in the buffer 14 is N.

Accordingly, when the number of wireless devices constituting the wireless network 10 is N, the coding means 17 of each wireless device 1 to 6 has a maximum of N packets P _{1 to} P _N stored in the buffer 14 in each period T. I know it is stored.

Then, when the number of packets actually extracted from the buffer 14 is N (when n = N−1), the coding unit 17 of each of the wireless devices 1 to 6 extracts the N packets P _{1 to} P that have been extracted. _A packet <P> = (P ₁ , P ₂ ,..., P _N ) composed of _N is generated.

Further, the coding means 17 of each of the wireless devices 1 to 6 has the extracted n + 1 packets P when the number of packets actually extracted from the buffer 14 is smaller than N (when n <N−1). Packets <P> = (P ₁ , P ₂ ,..., _{1 to} P _{n + 1} and N− (n + 1) “0” s set for packets that are not stored in the buffer 14 0, ..., 0, ... P _N ).

In this case, each element P _i (i = 1 to N) of the packet <P> is expressed by the following equation.

In Expression (1), B is obtained by dividing the packet size of each packet P _{1 to} P _N by “j” in a Galois field (GF2 ^j ) (j is an integer of 2 or more) and rounding up the decimal point. Become. Each element P _i1 , P _i2 ,..., P _iB of the packet <P _i > is composed of a numerical sequence of j bits “1” or “0”.

The coding unit 17 of each wireless device 1 to 6 holds a Galois field (GF2 ^j ) in advance, and when a packet <P> is generated, a numerical value is randomly extracted from the Galois field (GF2 ^j ) and a code string (c _{j1, c} j2, _···, to generate a c jN) (j = 1~N) . In this case, the code _{c j1, c j2, ···,} c jN , respectively, packet _{P 1,} P 2, · · ·, corresponds to _{P N.}

Then, the coding means 17 of each of the wireless devices 1 to 6 includes packets (packets P ₁ , P) that are not actually received by the receiving means 11 among the code strings (c _j1 , c _j2 ,..., C _jN ). ₂ ,..., P _N ) (at least one of c _j1 , c _j2 ,..., C _jN ) is set to “0” and the code vector <c _j > Generate. The code vector <c _j > is a code vector used for network coding in the wireless device j.

Then, the coding means 17 of each radio | wireless apparatus 1-6 produces | generates coding packet < _yj > by following Formula based on code vector < _cj > and packet <P>.

In Expression (2), each element c _j1 , c _j2 ,..., C _jN of the code vector <c _j > is composed of a numeric string of “1” or “0” of j bits.

As described above, the coding unit 17 of each of the wireless devices 1 to 6 multiplies the code vector <c _j > generated based on the randomly generated code by the packet <P> and the packets P ₁ , P ₂ , .., P _N is network-coded (ie, a coding packet <y _j > is generated).

  FIG. 3 is a configuration diagram of the combined packet PKT_CB obtained by combining the spontaneous packet and the coding packet in the first embodiment.

The combined packet PKT_CB includes a header, a spontaneous packet (Seq = k + 1), decoding information, and a coding packet (Seq = k). The header includes a broadcast address. The spontaneous packet (Seq = k + 1) includes a packet generated in the (k + 1) th (k is a positive integer) period. The decode information consists of a code vector <c _j >. The coding packet (Seq = k) is obtained by performing network coding on N packets including N−1 packets and spontaneous packets (Seq = k) received from other wireless devices in the k-th cycle by the method described above. Packet.

  Therefore, in FIG. 3, the sequence number Seq of the spontaneous packet (Seq = k + 1) is expressed as “k + 1”, and the sequence number Seq of the coding packet (Seq = k) is expressed as “k”.

  Subsequently, a generation method of the combined packet PKT_CB in the transmission unit 18 of each of the wireless devices 1 to 6 will be described.

When the transmission means 18 of each of the wireless devices 1 to 6 receives the spontaneous packet PKT_Self from the packet generation means 16 and receives the coding packet <y _j > and the code vector <c _j > from the coding means 17, the transmission means 18 receives the spontaneous packet PKT_Self “ “Spontaneous packet (Seq = k + 1)”, code vector <c _j > in “decode information”, coding packet <y _j > in “coding packet (Seq = k)”, broadcast address A combined packet PKT_CB is generated by storing in the “header”.

A decoding method of the coding packet <y _j > in the decoding unit 13 of each wireless device 1 to 6 will be described. In this case, it is assumed that each of the wireless devices 1 to 6 has received N-1 combined packets PKT_CB_1 to PKT_CB_N-1 from other N-1 wireless devices. The combined packets PKT_CB_1 to PKT_CB_N-1 include coding packets <y ₁ > to <y _N-1 >, respectively.

Upon receiving N-1 combined packets PKT_CB_1 to PKT_CB_N-1 from the control unit 12, the decoding unit 13 of each wireless device 1 to 6 performs coding from the received N-1 combined packets PKT_CB_1 to PKT_CB_N-1, respectively. Packets <y ₁ > to <y _N−1 > and code vectors <c ₁ > to <c _N−1 > are extracted. Further, the decoding unit 13 of each of the wireless devices 1 to 6 reads out the coding packet <y _j > generated by the network coding by the coding unit 17 and the code vector <c _j > from the buffer 14.

In this case, N including N−1 coding packets <y ₁ > to <y _N−1 > received from other wireless devices and coding packets <y _j > generated in the wireless devices 1 to 6. Each of the coding packets <y ₁ > to <y _N > is expressed by Expression (2).

Then, the decoding means 13 of each of the wireless devices 1 to 6 calculates the following expression based on the _N code vectors <c ₁ > to <c _N > and the N coding packets <y ₁ > to <y _N >. Generate.

Then, the decoding means 13 of each of the wireless devices 1 to 6 uses the inverse matrix <C> of the code matrix <C> made up of the code vectors <c ₁ > to <c _N > arranged at the head of the right side of Expression (3). ⁻¹ is calculated, and the calculated inverse matrix <C> ⁻¹ is multiplied on both sides of the equation (3). As a result, the decoding means 13 of each of the wireless devices 1 to 6 obtains the following formula.

Equation (4) right side of the element _{P 11,} P _{12 of, ···, P 1B, P 21} , P 22, ···, P B, ···, P N1, P N2, ···, P NB Are packets P ₁ , P ₂ ,..., _PN , respectively.

Therefore, the decoding means 13 of each of the wireless devices 1 to 6 can acquire the original N packets P _{1 to} P _N.

As described above, the decoding unit 13 of each of the wireless devices 1 to 6 acquires the original N packets P _{1 to} P _N by solving the simultaneous equations shown in Expression (3).

  A communication method in the wireless network 10 shown in FIG. 1 will be described. 4 to 6 are first to third conceptual diagrams for explaining a communication method in the wireless network 10 shown in FIG. 4 to 6, it is assumed that packets cannot be directly received between the wireless device 1 and the wireless devices 5 and 6.

  As shown in FIG. 4, in period T1, the packet generation means 16 of each of the wireless devices 1 to 6 generates single packets PKT1 (1) to PKT6 (1) with sequence numbers Seq = 1, respectively. The generated single packets PKT1 (1) to PKT6 (1) are stored in the buffer 14 and output to the transmission means 18. And the transmission means 18 of each radio | wireless apparatus 1-6 broadcasts the single packet PKT1 (1) -PKT6 (1) in the period T1. Note that (1) in each of the packets PKT1 (1) to PKT6 (1) represents the sequence number Seq = 1.

  The reception unit 11 of the wireless device 1 receives the single packets PKT2 (1), PKT3 (1), and PKT4 (1), and receives the received packets PKT2 (1), PKT3 (1), and PKT4 (1). ) To the control means 12. In this case, the reception unit 11 of the wireless device 1 cannot receive the single packets PKT5 (1) and PKT6 (1).

  When the control unit 12 of the wireless device 1 receives the packets PKT2 (1), PKT3 (1), and PKT4 (1), the destinations of the received packets PKT2 (1), PKT3 (1), and PKT4 (1) are broadcast. After confirming that the address is formed, the packets PKT2 (1), PKT3 (1), and PKT4 (1) are stored in the buffer 14, and the packets PKT2 (1), PKT3 (1), and PKT4 (1) are reproduced by the reproducing means 15. Output to. Then, the reproduction means 15 of the wireless device 1 reproduces the data of the packets PKT2 (1), PKT3 (1), and PKT4 (1), respectively, and the operator of the wireless device 1 as visual information by the display means (not shown). To give.

  The wireless device 2 receives the single packets PKT1 (1), PKT3 (1), PKT5 (1), and PKT6 (1), and performs the packets PKT1 (1), PKT3 ( 1), PKT5 (1) and PKT6 (1) are stored in the buffer 14, and the data of the packets PKT1 (1), PKT3 (1), PKT5 (1) and PKT6 (1) are reproduced by the reproducing means 15, respectively. To the operator of the wireless device 2 as visual information. In this case, the wireless device 2 cannot receive a single packet PKT4 (1).

  Further, the wireless device 3 receives a single packet PKT1 (1), PKT2 (1), PKT4 (1), PKT5 (1), PKT6 (1), and performs the packet PKT1 ( 1), PKT2 (1), PKT4 (1), PKT5 (1), PKT6 (1) are stored in the buffer 14, and packets PKT1 (1), PKT2 (1), PKT4 (1), PKT5 (1) , PKT6 (1) data is reproduced by the reproducing means 15 and given to the operator of the wireless apparatus 3 as visual information.

  Further, the wireless device 4 receives a single packet PKT1 (1), PKT3 (1), PKT5 (1), PKT6 (1), and in the same manner as the wireless device 1, the packets PKT1 (1), PKT3 ( 1), PKT5 (1) and PKT6 (1) are stored in the buffer 14, and the data of the packets PKT1 (1), PKT3 (1), PKT5 (1) and PKT6 (1) are reproduced by the reproducing means 15, respectively. To the operator of the wireless device 4 as visual information. In this case, the wireless device 4 cannot receive a single packet PKT2 (1).

  Further, the wireless device 5 receives a single packet PKT2 (1), PKT3 (1), PKT4 (1), PKT6 (1), and in the same manner as the wireless device 1, packets PKT2 (1), PKT3 ( 1), PKT4 (1), PKT6 (1) are stored in the buffer 14, and the data of the packets PKT2 (1), PKT3 (1), PKT4 (1), PKT6 (1) are respectively reproduced to reproduce the wireless device 5 Is given as visual information to the operator. In this case, the wireless device 5 cannot receive a single packet PKT1 (1).

  Further, the wireless device 6 receives a single packet PKT2 (1), PKT3 (1), PKT4 (1), PKT5 (1), and in the same manner as the wireless device 1, packets PKT2 (1), PKT3 ( 1), PKT4 (1), and PKT5 (1) are stored in the buffer 14, and the data of the packets PKT2 (1), PKT3 (1), PKT4 (1), and PKT5 (1) are reproduced to reproduce the wireless device 6 respectively. Is given as visual information to the operator. In this case, the wireless device 6 cannot receive a single packet PKT1 (1).

Thereafter, the packet generation means 16 of the wireless device 1 generates a single packet PKT1 (2) with a sequence number Seq = 2 in the cycle T2, stores the generated packet PKT1 (2) in the buffer 14, and transmits it. Output to means 18. In addition, the coding unit 17 of the wireless device 1 reads out the packets PKT1 (1), PKT2 (1), PKT3 (1), and PKT4 (1) stored in the buffer 14 in the period T2, and generates a Galois field (GF2 ^j ) Are randomly generated from c ₁₁ , c ₁₂ , c ₁₃ , c ₁₄ , c ₁₅ , c ₁₆ . Then, the coding unit 17 of the wireless device 1 does not receive the packets PKT5 (1) and PKT6 (1) because the receiving unit 11 cannot receive the packets PKT1 (1), PKT2 (1), PKT3 (1), PKT4 ( 1) is generated as packets P ₁₁ , P ₁₂ , P ₁₃ , and P ₁₄ , respectively, and packets <P ₁ > = (P ₁₁ , P ₁₂ , P ₁₃ , P ₁₄ , 0, 0) are generated, and codes c ₁₅ , Each of c ₁₆ is set to “0” to generate a code vector <c ₁ > = (c ₁₁ , c ₁₂ , c ₁₃ , c ₁₄ , 0, 0).

Then, the coding unit 17 of the wireless device 1 uses the packet <P ₁ > = (P ₁₁ , P ₁₂ , P ₁₃ , P ₁₄ , 0, 0) and the code vector <c ₁ > = (c ₁₁ , c ₁₂ , c ₁₃ , c ₁₄ , 0, 0), the coding packet <y ₁ > = (c ₁₁ , c ₁₂ , c ₁₃ , c ₁₄ , 0, 0) × (P ₁₁ , P ₁₂ , P ₁₃ , P ₁₄ , 0, 0) ^T is generated, and the generated coding packet <y ₁ > = (c ₁₁ , c ₁₂ , c ₁₃ , c ₁₄ , 0, 0) × (P ₁₁ , P ₁₂ , P ₁₃ , P ₁₄ , 0, 0) ^T and the code vector <c ₁ > = (c ₁₁ , c ₁₂ , c ₁₃ , c ₁₄ , 0, 0) are stored in the buffer 14 and output to the transmission means 18. To do.

The transmission unit 18 of the wireless device 1 receives the packet PKT1 (2) from the packet generation unit 16 in the period T2, and the coding packet <y ₁ > = (c ₁₁ , c ₁₂ , c ₁₃ , c ₁₄ , 0,0) × (P ₁₁ , P ₁₂ , P ₁₃ , P ₁₄ , 0, 0) ^T and the sign vector <c ₁ > = (c ₁₁ , c ₁₂ , c ₁₃ , c ₁₄ , 0, 0) receive.

Then, the transmission means 18 of the wireless device 1 stores the broadcast address FF in the “header”, stores the packet PKT1 (2) in “spontaneous packet (Seq = k + 1)”, and the code vector <c ₁ > = (c ₁₁ , c ₁₂ , c ₁₃ , c ₁₄ , 0, 0) are stored in “decode information”, and the coding packet <y ₁ > = (c ₁₁ , c ₁₂ , c ₁₃ , c ₁₄ , 0, 0) × ( P ₁₁ , P ₁₂ , P ₁₃ , P ₁₄ , 0, 0) ^T is stored in the “coding packet (Seq = k)” and the combined packet PKT_CB1 (2) = [FF / PKT1 (2) / (c ₁₁ , _{c 12, c 13, c 14} , 0,0) / (c 11, c 12, c 13, c 14, 0,0) × (P 11, P 12, P 13, P 14, 0,0) T ] Is generated. Thereafter, the transmission unit 18 of the wireless device 1 transmits the combined packet PKT_CB1 (2) = [FF / PKT1 (2) / (c ₁₁ , c ₁₂ , c ₁₃ , c ₁₄ , 0, 0) / (c) in the period T2. ₁₁ , c ₁₂ , c ₁₃ , c ₁₄ , 0, 0) × (P ₁₁ , P ₁₂ , P ₁₃ , P ₁₄ , 0, 0) ^T ] is broadcast (see FIG. 5).

Further, in the period T2, the wireless device 2 is similar to the wireless device 1, and the combined packet PKT_CB2 (2) = [FF / PKT2 (2) / (c ₂₁ , c ₂₂ , c ₂₃ , 0, c ₂₅ , c ₂₆ ) / (c ₂₁ , c ₂₂ , c ₂₃ , 0, c ₂₅ , c ₂₆ ) × (P ₂₁ , P ₂₂ , P ₂₃ , 0, P ₂₅ , P ₂₆ ) ^T ]], and the generated bond packet _{PKT_CB2 (2) = [FF /} PKT2 (2) / (c 21, c 22, c 23, 0, c 25, c 26) / (c 21, c 22, c 23, 0, c 25, c 26 ) × (P ₂₁ , P ₂₂ , P ₂₃ , 0, P ₂₅ , P ₂₆ ) ^T ] (see FIG. 5). In this case, the packets P ₂₁ , P ₂₂ , P ₂₃ , P ₂₅ , and P ₂₆ are composed of packets PKT1 (1), PKT2 (1), PKT3 (1), PKT5 (1), and PKT6 (1), respectively.

Further, the wireless device 3, in the period T2, in the same manner as the wireless device 1, combined packet _{PKT_CB3 (2) = [FF /} PKT3 (2) / (c 31, c 32, c 33, c 34, c 35, c ₃₆ ) / (c ₃₁ , c ₃₂ , c ₃₃ , c ₃₄ , c ₃₅ , c ₃₆ ) × (P ₃₁ , P ₃₂ , P ₃₃ , P ₃₄ , P ₃₅ , P ₃₆ ) ^T ] the resulting combined packet _{PKT_CB3 (2) = [FF /} PKT3 (2) / (c 31, c 32, c 33, c 34, c 35, c 36) / (c 31, c 32, c 33, c 34, c ₃₅ , c ₃₆ ) × (P ₃₁ , P ₃₂ , P ₃₃ , P ₃₄ , P ₃₅ , P ₃₆ ) ^T ] (see FIG. 5). In this case, the packets P ₃₁ , P ₃₂ , P ₃₃ , P ₃₄ , P ₃₅ , P ₃₆ are packet PKT 1 (1), PKT 2 (1), PKT 3 (1), PKT 4 (1), PKT 5 (1), respectively. , PKT6 (1).

Further, in the period T2, the wireless device 4 is similar to the wireless device 1, and the combined packet PKT_CB4 (2) = [FF / PKT4 (2) / (c ₄₁ , 0, c ₄₃ , c ₄₄ , c ₄₅ , c ₄₆ ) / (c ₄₁ , 0, c ₄₃ , c ₄₄ , c ₄₅ , c ₄₆ ) × (P ₄₁ , 0, P ₄₃ , P ₄₄ , P ₄₅ , P ₄₆ ) ^T ] and the generated coupling packet _{PKT_CB4 (2) = [FF /} PKT4 (2) / (c 41, 0, c 43, c 44, c 45, c 46) / (c 41, 0, c 43, c 44, c 45, c 46 ) × (P ₄₁ , 0, P ₄₃ , P ₄₄ , P ₄₅ , P ₄₆ ) ^T ] is broadcast (see FIG. 5). In this case, packets P ₄₁ , P ₄₃ , P ₄₄ , P ₄₅ , and P ₄₆ are composed of packets PKT 1 (1), PKT 3 (1), PKT 4 (1), PKT 5 (1), and PKT 6 (1), respectively.

Further, the wireless device 5, in the period T2, in the same manner as the wireless device 1, combined packet _{PKT_CB5 (2) = [FF /} PKT5 (2) / (0, c 52, c 53, c 54, c 55, c ₅₆ ) / (0, c ₅₂ , c ₅₃ , c ₅₄ , c ₅₅ , c ₅₆ ) × (0, P ₅₂ , P ₅₃ , P ₅₄ , P ₅₅ , P ₅₆ ) ^T ] and the generated coupling packet _{PKT_CB5 (2) = [FF /} PKT5 (2) / (0, c 52, c 53, c 54, c 55, c 56) / (0, c 52, c 53, c 54, c 55, c 56 ) × (0, P ₅₂ , P ₅₃ , P ₅₄ , P ₅₅ , P ₅₆ ) ^T ] (see FIG. 5). In this case, packets P ₅₂ , P ₅₃ , P ₅₄ , P ₅₅ , and P ₅₆ are composed of packets PKT 2 (1), PKT 3 (1), PKT 4 (1), PKT 5 (1), and PKT 6 (1), respectively.

Furthermore, the radio device 6, in the period T2, in the same manner as the wireless device 1, combined packet _{PKT_CB6 (2) = [FF /} PKT6 (2) / (0, c 62, c 63, c 64, c 65, c ₆₆ ) / (0, c ₆₂ , c ₆₃ , c ₆₄ , c ₆₅ , c ₆₆ ) × (0, P ₆₂ , P ₆₃ , P ₆₄ , P ₆₅ , P ₆₆ ) ^T ] and the generated bond packet _{PKT_CB6 (2) = [FF /} PKT6 (2) / (0, c 62, c 63, c 64, c 65, c 66) / (0, c 62, c 63, c 64, c 65, c 66 ) × (0, P ₆₂ , P ₆₃ , P ₆₄ , P ₆₅ , P ₆₆ ) ^T ] (see FIG. 5). In this case, the packets P ₆₂ , P ₆₃ , P ₆₄ , P ₆₅ , P ₆₆ are composed of packets PKT 2 (1), PKT 3 (1), PKT 4 (1), PKT 5 (1), and PKT 6 (1), respectively.

  The reception unit 11 of the wireless device 1 receives the combined packets PKT_CB2 (2), PKT_CB3 (2), and PKT_CB4 (2) from the wireless devices 2, 3, and 4 in the period T2, and receives the received combined packet PKT_CB2 (2 ), PKT_CB3 (2) and PKT_CB4 (2) are output to the control means 12.

The control unit 12 of the wireless device 1 receives the combined packets PKT_CB2 (2), PKT_CB3 (2), and PKT_CB4 (2) from the receiving unit 11, and the combined packets PKT_CB2 (2), PKT_CB3 (2), and PKT_CB4 (2) respectively. It detects that a coding packet <y ₂ >, <y ₃ >, <y ₄ > is included, and outputs combined packets PKT_CB 2 (2), PKT_CB 3 (2), and PKT_CB 4 (2) to the decoding means 13.

Upon receiving the combined packets PKT_CB2 (2), PKT_CB3 (2), and PKT_CB4 (2) from the control unit 12, the decoding unit 13 of the wireless device 1 receives the coding packet <y ₁ > = (c ₁₁ , c ₁₂ , c ₁₃ , c ₁₄ , 0, 0) × (P ₁₁ , P ₁₂ , P ₁₃ , P ₁₄ , 0, 0) ^T and the sign vector <c ₁ > = (c ₁₁ , c ₁₂ , c ₁₃ , c ₁₄ , Read 0,0).

Combined packet PKT_CB2 (2) _{is, PKT_CB2 (2) = [FF} / PKT2 (2) / (c 21, c 22, c 23, 0, c 25, c 26) / (c 21, c 22, c 23, 0, c ₂₅ , c ₂₆ ) × (P ₂₁ , P ₂₂ , P ₂₃ , 0, P ₂₅ , P ₂₆ ) ^T ], and the combined packet PKT_CB3 (2) is PKT_CB3 (2) = [FF / PKT3 ( 2) / (c ₃₁ , c ₃₂ , c ₃₃ , c ₃₄ , c ₃₅ , c ₃₆ ) / (c ₃₁ , c ₃₂ , c ₃₃ , c ₃₄ , c ₃₅ , c ₃₆ ) × (P ₃₁ , P ₃₂ , P ₃₃ , P ₃₄ , P ₃₅ , P ₃₆ ) ^T ], and the combined packet PKT_CB4 (2) is PKT_CB4 (2) = [FF / PKT4 (2) / (c ₄₁ , 0, c ₄₃ , c ₄₄ , _{c 45,} c _{46 / (C 41, 0, c} 43, c 44, c 45, c 46) consists _{× (P 41, 0, P} 43, P 44, P 45, P 46) T].

Then, the decoding unit 13 of the wireless device 1 receives the packet P ₁₅ = PKT5 (1) and the packet P ₁₆ = PKT6 (1) in the period T1, and thus receives the packet P ₁₅ = PKT6 (1) from the wireless devices 2 to 4. combined packet PKT_CB2 (2), PKT_CB3 (2 ), the decoding information _{PKT_CB4 (2) = (c 21} , c 22, c 23, 0, c 25, c 26), (c 31, c 32, c 33, c ₃₄ , c ₃₅ , c ₃₆ ), (c ₄₁ , 0, c ₄₃ , c ₄₄ , c ₄₅ , c ₄₆ ), the packet P ₅ = PKT ₅ (1 ) And packet P ₆ = PKT6 (1) is coded packet <y ₂ > = (c ₂₁ , c ₂₂ , c ₂₃ , 0, c ₂₅ , c ₂₆ ) × (P ₂₁ , P ₂₂ , P ₂₃ , 0, P ₂₅ , P ₂₆ ) ^T , <y ₃ > = (c ₃₁ , c ₃₂ , c ₃₃ , c ₃₄ , c ₃₅ , c ₃₆ ) × (P ₃₁ , P ₃₂ , P ₃₃ , P ₃₄ , P ₃₅ , P ₃₆ ) ^T , <y ₄ > = (c ₄₁ , 0, c ₄₃ , c ₄₄ , c ₄₅ , c ₄₆ ) × (P ₄₁ , 0, P ₄₃ , P ₄₄ , P ₄₅ , P ₄₆ ) Select from ^T.

In this case, each of the coding packets <y ₂ >, <y ₃ >, <y ₄ > has information of packet P ₅ = PKT5 (1) and packet P ₆ = PKT6 (1), and There are two packets that the receiving means 11 could not receive in the period T1, packet P ₅ = PKT5 (1) and packet P ₆ = PKT6 (1).

Therefore, the decoding unit 13 of the wireless device 1 selects any two coding packets from the coding packets <y ₂ >, <y ₃ >, <y ₄ >. In this case, it is assumed that the decoding unit 13 of the wireless device 1 selects _two coding packets <y ₂ > and <y ₃ >.

Then, the decoding means 13 of the wireless device 1 receives the packets P ₁ = PKT1 (1), P ₂ = PKT2 (1), P ₃ = PKT3 (1), and P ₄ = PKT4 (1) stored in the buffer 14. Read the packet P ₁ = PKT1 (1), P ₂ = PKT2 (1), P ₃ = PKT3 (1), P ₄ = PKT4 (1) to packet P ₁ = ( _1, 0, 0, 0 , 0, 0, P ₁ ), P ₂ = (0, ₁ , 0, 0, 0, 0, P ₂ ), P ₃ = (0, 0, 1, 0, 0, 0, P ₃ ), P ₄ = (0, 0, 0, 1, 0, 0, P ₄ ) is generated.

Then, the decoding means 13 of the wireless device 1 uses the packet P ₁ = ( _1, 0, 0, 0, 0, 0, P ₁ ), P ₂ = (0, ₁ , 0, 0, 0, 0, P _2). ), P ₃ = (0, 0, 1, 0, 0, 0, P ₃ ), P ₄ = (0, 0, 0, 1, 0, 0, P ₄ ) and coding packet <y ₂ >, <Y ₃ >, code vector <c ₂ > = (c ₂₁ , c ₂₂ , c ₂₃ , 0, c ₂₅ , c ₂₆ ), <c ₃ > = (c ₃₁ , c ₃₂ , c ₃₃ , c ₃₄ , c ₃₅ , c ₃₆ ) and the following equation is created.

After that, the decoding unit 13 of the wireless device 1 calculates a matrix of codes arranged before P ₁ , P ₂ , P ₃ , P ₄ , d, and d arranged vertically on the right side of the equation (5). An inverse matrix is calculated, the calculated inverse matrix is multiplied on both sides of the equation (5), and the packets P ₁ , P ₂ , P ₃ , P ₄ , P ₅ , and P ₆ are decoded by the following equation.

Then, the decoding means the wireless device 1 13 acquires the packet _P 5 = PKT5 (1) and the packet _P 6 = PKT6 a (1).

  Then, the decoding unit 13 of the wireless device 1 extracts the packets PKT2 (2), PKT3 (2), and PKT4 (2) from the combined packets PKT_CB2 (2), PKT_CB3 (2), and PKT_CB4 (2), respectively. The packets PKT2 (2), PKT3 (2), PKT4 (2) and the decoded packets PKT5 (1), PKT6 (1) are output to the reproducing means 15.

  Then, the reproduction unit 15 of the wireless device 1 reproduces the data of the packets PKT2 (2), PKT3 (2), PKT4 (2), PKT5 (1), and PKT6 (1), respectively, to the operator of the wireless device 1. Give as visual information.

  Since the wireless device 2 has not received the packet PKT4 (1) from the wireless device 4 in the period T1, the combined packets PKT_CB1 (2), PKT_CB3 (2), PKT_CB5 (2), Based on PKT_CB6 (2), packet PKT4 (1) is acquired. Then, the wireless device 2 reproduces the data of the packets PKT1 (2), PKT3 (2), PKT4 (1), PKT5 (2), and PKT6 (2).

  Further, since the wireless device 4 has not received the packet PKT2 (1) from the wireless device 2 in the period T1, the combined packets PKT_CB1 (2), PKT_CB3 (2), PKT_CB5 (2) are the same as the wireless device 1. ), PKT_CB6 (2), the packet PKT2 (1) is acquired. Then, the wireless device 4 reproduces the data of the packets PKT1 (2), PKT2 (1), PKT3 (2), PKT5 (2), and PKT6 (2).

  Further, since the wireless device 5 has not received the packet PKT1 (1) from the wireless device 1 in the cycle T1, the combined packets PKT_CB2 (2), PKT_CB3 (2), PKT_CB3 (2) are the same as the wireless device 1. ), PKT_CB4 (2), and PKT_CB6 (2), the packet PKT1 (1) is acquired. Then, the wireless device 5 reproduces the data of the packets PKT1 (1), PKT2 (2), PKT3 (2), PKT4 (2), and PKT6 (2).

  Further, since the wireless device 6 has not received the packet PKT1 (1) from the wireless device 1 in the period T1, similarly to the wireless device 1, the combined packets PKT_CB2 (2), PKT_CB3 (2), PKT_CB4 (2 ), PKT_CB5 (2), the packet PKT1 (1) is acquired. Then, the wireless device 6 reproduces the data of the packets PKT1 (1), PKT2 (2), PKT3 (2), PKT4 (2), and PKT5 (2), respectively.

  The wireless device 3 receives all of the packets PKT1 (1), PKT2 (1), PKT4 (1), PKT5 (1), and PKT6 (1) in the period T1, and therefore decodes the coding packet. Don't do it. Then, the wireless device 3 reproduces the data of the packets PKT1 (2), PKT2 (2), PKT4 (2), PKT5 (2), and PKT6 (2).

  Thereafter, the wireless devices 1 to 6 generate combined packets PKT_CB1 (3) to PKT_CB6 (3), respectively, in the period T3 by the method described above, and generate the generated combined packets PKT_CB1 (3) to PKT_CB6 (3). Broadcast (see FIG. 6).

  Then, the wireless device 1 receives and reproduces the packets PKT2 (3), PKT3 (3), PKT4 (3), PKT5 (2), and PKT6 (2) in the period T3 by the method described above. Further, the wireless device 2 receives and reproduces the packets PKT1 (3), PKT3 (3), PKT4 (2), PKT5 (3), and PKT6 (3) in the period T3 by the method described above. Further, the wireless device 3 receives and reproduces the packets PKT1 (3), PKT2 (3), PKT4 (3), PKT5 (3), and PKT6 (3) in the period T3 by the method described above. Further, the wireless device 4 receives and reproduces the packets PKT1 (3), PKT2 (2), PKT3 (3), PKT5 (3), and PKT6 (3) in the period T3 by the method described above. Further, the wireless device 5 receives and reproduces the packets PKT1 (2), PKT2 (3), PKT3 (3), PKT4 (3), and PKT6 (3) in the period T3 by the method described above. Further, the wireless device 6 receives and reproduces the packets PKT1 (2), PKT2 (3), PKT3 (3), PKT4 (3), and PKT5 (3) in the period T3 by the above-described method (FIG. 6). reference).

  As described above, the wireless device 1 cannot receive the packets PKT5 (1) and PKT6 (1) from the wireless devices 5 and 6 in the cycle T1, but the combined packet from the wireless devices 2 to 4 in the cycle T2. Based on PKT_CB2 (2), PKT_CB3 (2), and PKT_CB4 (2), packets PKT5 (1) and PKT6 (1) can be received. Further, the wireless device 1 cannot receive the packets PKT5 (2) and PKT6 (2) from the wireless devices 5 and 6 in the cycle T2, but in the cycle T3, the combined packet PKT_CB2 (3 ), PKT_CB3 (3), and PKT_CB4 (3), the packets PKT5 (2) and PKT6 (3) can be received.

  Therefore, according to the present invention, the arrival rate of the packets PKT5 (1), PKT6 (1), PKT5 (2), PKT6 (3),.

  Further, the delay time when the packets PKT5 (1), PKT6 (1), PKT5 (2), PKT6 (3),... Reach the wireless device 1 from the wireless devices 5 and 6 becomes 16.7 ms or less. Therefore, PKT5 (1), PKT6 (1), PKT5 (2), PKT6 (3),... Can reach the wireless device 1 from the wireless devices 5 and 6 within an allowable delay = 50 ms. As a result, the wireless devices 1 to 6 can execute a battle game.

  FIG. 7 is a timing chart of wireless communication in the wireless network 10 shown in FIG.

  The wireless devices 1 to 6 broadcast single packets PKT1 (1) to PKT6 (1) having a sequence number Seq = 1 in the period T1, respectively. After that, in the period T2, the wireless devices 1 to 6 each have the coding packet PKT_cd (1) obtained by network coding the packets PKT1 (1) to PKT6 (1) having the sequence number Seq = 1 and the single sequence number Seq = 2. The combined packets PKT_CB1 (2) to PKT_CB6 (2) with one packet PKT1 (2) to PKT6 (2) are broadcast. Further, in the period T3, the wireless devices 1 to 6 each have a coding packet PKT_cd (2) obtained by network-coding packets PKT1 (2) to PKT6 (2) having a sequence number Seq = 2 and a single sequence number Seq = 3. The combined packets PKT_CB1 (3) to PKT_CB6 (3) with one packet PKT1 (3) to PKT6 (3) are broadcast. Hereinafter, the wireless devices 1 to 6 perform wireless communication by repeatedly executing the same operation.

  As described above, the wireless devices 1 to 6 perform network coding and broadcast the packet PKT having the same sequence number after the period T2.

  On the other hand, in the conventional network coding described in Non-Patent Documents 2 and 3, the wireless device A passes the packets PKTA (1), PKTA (2), and PKTA (3) with sequence numbers Seq = 1, 2, and 3 three times. The wireless device B transmits the packets PKTA (1), PKTA (2), and PKTA (3) after network coding. Thus, in conventional network coding, each wireless device performs network coding of a plurality of packets having different sequence numbers.

  Accordingly, each of the wireless devices 1 to 6 performs network coding of the packet by a method different from the conventional network coding.

  By transmitting network-coded packets with the same sequence number, multiple packets that did not arrive in the kth cycle can be reached simultaneously in the (k + 1) th cycle, thus maintaining the packet's immediacy it can. As a result, a competitive game can be executed.

  A simulation result of the packet error rate when the communication method described above is used will be described.

  The simulation conditions are as follows. The wireless communication range is set to a range of 500 m × 250 m, and the communication mode is set to IEEE802.11g. The communication rate of each wireless device is 6 Mbps, and the fading rice coefficient K is K = 4.84. Further, the long-term average value in the logarithmic normal distribution of shadowing is 4, the propagation method is the two-ray method, the packet generation cycle is 16.7 ms, and the packet size in the IP (Internet Protocol) layer is 50 bytes. It was. Furthermore, the comparison target is a normal broadcast, FEC (Forward Error Correction) (1/1), FEC (2/1), and a transfer method using MPR (Multi Point Relay) (hereinafter referred to as “MPR”). .

  FIG. 8 is a diagram illustrating the relationship between the average packet error rate and the number of wireless devices. In FIG. 8, the vertical axis represents the average packet error rate, and the horizontal axis represents the number of wireless devices. A curve k1 shows the relationship between the average packet error rate when the communication method according to the present invention is used and the number of wireless devices, and a curve k2 shows the average packet error rate when FEC (2/1) is used. The curve k3 shows the relationship between the average packet error rate and the number of wireless devices when FEC (1/1) is used, and the curve k4 uses a normal broadcast. The relationship between the average packet error rate and the number of wireless devices is shown, and the curve k5 shows the relationship between the average packet error rate and the number of wireless devices when MPR is used.

  The average packet error rate when using the communication method according to the present invention is lower than when using other methods even if the number of wireless devices increases to 50 (see curves k1 to k5). In particular, when normal broadcast, FEC (1/1), FEC (2/1), and MPR are used, the average packet error rate increases when the number of wireless devices exceeds 20 (curve). When the communication method according to the present invention is used, the average packet error rate hardly increases even when the number of wireless devices exceeds 20, and is lower than 1% (curve). k1).

  FIG. 9 is a diagram illustrating the relationship between the maximum packet error rate and the number of wireless devices. In FIG. 9, the vertical axis represents the maximum packet error rate, and the horizontal axis represents the number of wireless devices. A curve k6 indicates the relationship between the maximum packet error rate when using the communication method according to the present invention and the number of wireless devices, and a curve k7 indicates the maximum packet error rate when FEC (2/1) is used. The curve k8 shows the relationship between the maximum packet error rate and the number of radio devices when FEC (1/1) is used, and the curve k9 uses a normal broadcast. The relationship between the maximum packet error rate and the number of wireless devices in the case of using the MPR is shown, and the curve k10 indicates the relationship between the maximum packet error rate and the number of wireless devices when the MPR is used.

  The maximum packet error rate when using the communication method according to the present invention is lower than when using other methods even if the number of wireless devices increases to 50 (see curves k6 to k10). In particular, when normal broadcast, FEC (1/1), and FEC (2/1) are used, the maximum packet error rate increases when the number of wireless devices exceeds 30 (see curves k7 to k9). ) When MPR is used, the maximum packet error rate increases when the number of wireless devices exceeds 20 (see curve k10). However, when the communication method according to the present invention is used, the maximum packet error rate is increased. The number of wireless devices hardly increases until the number of wireless devices is 40, and is as low as about 1% even when the number of wireless devices is 50 (see curve k6).

  Therefore, it has been found that the communication method according to the present invention satisfies a packet arrival rate = 99% or more, which is a necessary performance in a competitive game.

[Embodiment 2]
FIG. 10 is a schematic block diagram showing the configuration of the radio apparatuses 1 to 6 shown in FIG. 1 according to the second embodiment.

  Each of radio apparatuses 1 to 6 shown in FIG. 1 includes radio apparatus 1A shown in FIG. 10 in the second embodiment. The wireless device 1A is obtained by replacing the decoding unit 13, the coding unit 17 and the transmission unit 18 of the wireless device 1 shown in FIG. 2 with the decoding unit 13A, the coding unit 17A and the transmission unit 18A, respectively, Is the same.

  The decoding unit 13A receives from the control unit 12 a packet including the code string FC1 transmitted from the other wireless device and the address of the other wireless device, and receives the code string FC1 and the address of the other wireless device from the received packet. And the extracted code string FC1 and the address of another wireless device are associated with each other and held in advance. Then, the decoding unit 13A performs the coding packet based on the combined packet PKT_CBB transmitted from the other wireless device, the code string FC1 held in advance, and the coding packet PKT_cd network-coded by the coding unit 17A by a method described later. Decode PKT_cd. The decoding means 13A performs the same function as the decoding means 13 in other respects.

Before the periodic transmission / reception of the packet PKT is started, the coding unit 17A receives the code string FC1 = (c _j1 , c _j2 , c _j3 , c) from the Galois field (GF2 ^j ) in the wireless device j on which the coding unit 17A is installed. _{j4, c} j5, _{c j6)} randomly generates and outputs the generated allowed code string _FC1 = a _{(c j1, c j2, c} j3, c j4, c j5, c j6) to the transmitting unit 18A.

Further, the coding means 17A reads a single packet PKT1 (k) to PKTn (k) of sequence number Seq = k from the buffer 14 in the (k + 1) th cycle, and reads the read packets PKT1 (k) to PKTn ( Based on k), a bit string FC2 = (b ₁ , b ₂ , b ₃ , b ₄ , b ₅ , b ₆ ) indicating the presence or absence of the packets PKT1 (k) to PKT6 (k) is generated. More specifically, when n = 6, the coding unit 17A has a bit string FC2 = (1,1,1,1,1,1) indicating that all of the packets PKT1 (k) to PKT6 (k) exist. 1) is generated. Further, when n <6, for example, the coding unit 17A generates a bit string FC2 = (1, 1, 0, 1, 1, 1) indicating that the packet PKT3 (k) does not exist. Note that the coding unit 17A generates the bit string FC2 in the same manner even when the packets PKT1 (k), PKT2 (k), PKT4 (k), PKT5 (k), and PKT6 (k) do not exist.

Then, the coding unit 17A generates a code string FC1 = (c _j1 , c _j2 , c _j3 , c _j4 , c _j5 , c _j6 ) and a bit string FC2 = (b ₁ , b ₂ , b ₃ , b ₄ , b ₅ , b ₆ ) and a code vector <c _j > is generated. More specifically, the coding unit 17A, when the bit string FC2 is composed of (1, 1, 1, 1, 1, 1), the code vector <c _j > = (c _j1 , c _j2 , c _j3 , c _j4 , C _j5 , c _j6 ). Further, the coding means 17A, when the bit string FC2 is composed of (1, 1, 0, 1, 1, 1), the code vector <c _j > = (c _j1 , c _j2 , 0, c _j4 , c _j5 , c _j6 ) is generated. Note that the coding unit 17A similarly applies the code vector <c _j even when the elements b ₁ , b ₂ , b ₄ , b ₅ , and b ₆ other than the _third element b ₃ of the bit string FC2 are “0”. > Is generated.

The coding unit 17A then transmits the packets PKT1 (k) to PKTn (k) to the network by the same method as the coding unit 17 based on the code vector <c _j > and the packets PKT1 (k) to PKTn (k). The coding packet PKT_cd (k) is generated by coding.

Then, the coding unit 17A outputs the bit string FC2 = (b ₁ , b ₂ , b ₃ , b ₄ , b ₅ , b ₆ ) and the coding packet PKT_cd (k) to the transmission unit 18A.

  Other than that, the coding means 17A performs the same function as the coding means 17.

Upon receiving the code string FC1 = (c _j1 , c _j2 , c _j3 , c _j4 , c _j5 , c _j6 ) from the coding means 17A, the transmission means 18A receives the received code string FC1 = (c _j1 , c _j2 , c _j3 , c _j4 , c _j5 , c _j6 ) and the address Addj of the wireless device j are generated, and the generated packet PKT is transmitted to all other wireless devices by unicast.

Further, the transmission unit 18A receives the packet PKTj (k + 1) from the packet generation unit 16 in the (k + 1) -th cycle, and the bit string FC2 = (b ₁ , b ₂ , b ₃ , b ₄ , b ₅ , b ₆ ) A coding packet PKT_cd (k) is received from the coding means 17A. Then, the transmission unit 18A reads the packet PKTj (k) generated and stored by the packet generation unit 16 in the kth cycle from the buffer 14.

Then, the transmission unit 18A transmits the packet PKTj (k), the packet PKTj (k + 1), the bit string FC2 = (b ₁ , b ₂ , b ₃ , b ₄ , b ₅ , b ₆ ) and the coding packet PKT_cd (k ), And broadcast the generated combined packet PKT_CBB.

  The transmitting unit 18A performs the same function as the transmitting unit 18 in other respects.

  FIG. 11 is a configuration diagram in Embodiment 2 of a packet obtained by combining a spontaneous packet and a coding packet.

  The combined packet PKT_CBB is obtained by adding a spontaneous packet (Seq. = K) to the combined packet PKT_CB shown in FIG. 3 and is otherwise the same as the combined packet PKT_CB.

In the combined packet PKT_CBB, the decode information is composed of a bit string FC2 = (b ₁ , b ₂ , b ₃ , b ₄ , b ₅ , b ₆ ).

  The spontaneous packet (Seq. = K) is composed of a single packet PKT generated in the kth cycle in the wireless device that transmits the combined packet PKT_CBB in the (k + 1) th cycle.

  As described above, in the second embodiment, each of the wireless devices 1 to 6 has not only the spontaneous packet (Seq. = K + 1) generated in the (k + 1) th cycle but the kth in the (k + 1) th cycle. The combined packet PKT_CBB is generated including the spontaneous packet (Seq. = K) generated in the period of, and the generated combined packet PKT_CBB is broadcast. As a result, the arrival rate of the packet PKT (k) that has not reached the transmission destination due to packet collision in the k-th cycle can be improved.

A decoding method of the coding packet <y _j > in the decoding unit 13A shown in FIG. 10 will be described. In this case, it is assumed that each of the wireless devices 1 to 6 receives N−1 combined packets PKT_CBB_1 to PKT_CBB_N−1 from other N−1 wireless devices. Combined packet PKT_CBB_1~PKT_CBB_N-1, respectively, the bit string FC2_1~FC2_N-1 and coding a packet _<y 1> ~ containing _{<y N-1>.}

The decoding means 13A of each of the wireless devices 1 to 6 extracts the bit strings FC2_1 to FC2_N-1 and the coding packets <y ₁ > to <y _N-1 > from the combined packets PKT_CBB_1 to PKT_CBB_N−1, respectively.

Then, the decoding unit 13A of each of the wireless devices 1 to 6 converts the N−1 code strings FC1_1 to FC1_N−1 transmitted from the other N−1 wireless devices to the other N−1 wireless devices. Since it is held in association with the address, N−1 code vectors <c ₁ > to <c _N−1 > are obtained based on the code strings FC1_1 to FC1_N-1 and the bit strings FC2_1 to FC2_N-1. Generate. In this case, the code strings FC1_1 to FC1_N-1 correspond to the bit strings FC2_1 to FC2_N-1, respectively.

More specifically, the decoding means 13A of the wireless device 1 through 6, the code string FC1_1 and bit string FC2_1 respectively _{FC1_1} = _{(c 11} corresponding to each _{other, c 12, c 13, c} 14, c 15, c 16 ), FC2_1 = (1,1,1,1,1,1), the code vector <c ₁ > = (c ₁₁ , c ₁₂ , c ₁₃ , c ₁₄ based on the code string FC1_1 and the bit string FC2_1. , C ₁₅ , c ₁₆ ). Further, the decoding unit 13A of the wireless device 1 through 6, the code string FC1_1 and bit string FC2_1 respectively _{FC1_1 = (c 11, c 12} , c 13, c 14, c 15, c 16), FC2_1 = (1,0 , _{1, 1, 1, 1} ), a code vector <c ₁ > = (c ₁₁ , 0, c ₁₃ , c ₁₄ , c ₁₅ , c ₁₆ ) is generated based on the code string FC1_1 and the bit string FC2_1. To do. The decoding means 13A of each of the wireless devices 1 to 6 is the same when the elements b ₁ , b ₃ , b ₄ , b ₅ , and b ₆ other than the second element b ₂ of the bit string FC2_1 are “0”. Thus, a code vector <c ₁ > is generated.

Thereafter, the decoding unit 13A of each of the wireless devices 1 to 6 similarly performs code vectors <c ₂ > to <c _N−1 based on the code strings FC1_2 to FC1_N−1 and the bit strings FC2_2 to FC2_N _−1. > Is generated.

Further, the decoding unit 13A of each of the wireless devices 1 to 6 reads out the coding packet <y _j > network-coded by the coding unit 17A and the code vector <c _j > used for the network coding from the buffer 14.

As a result, the decoding means 13A of each of the wireless devices 1 to 6 obtains N code vectors <c ₁ > to <c _N > and N coding packets <y ₁ > to <y _N >.

Then, the decoding means 13A of each of the wireless devices 1 to 6 is based on the N code vectors <c ₁ > to <c _N > and the N coding packets <y ₁ > to <y _N > as described above. The coding packets <y ₁ > to <y _N > are decoded by the same method as that in the decoding means 13.

  As described above, in the second embodiment, the decoding unit 13A determines that the code vector <based on the code string FC1 transmitted and held in advance from another wireless device and the bit string FC2 included in the combined packet PKT_CBB. c> is generated, and the coding packet <y> is decoded using the generated code vector <c>.

  In the second embodiment, radio apparatuses 1 to 6 generate and broadcast packets PKT1 (1) to PKT6 (1), respectively, in period T1 (see FIG. 5). Each of the wireless devices 1 to 6 reproduces the data of the packet PKT (1) received from the other wireless device and gives it to the operator of each of the wireless devices 1 to 6 as visual information.

Thereafter, the packet generation means 16 of the wireless device 1 generates a single packet PKT1 (2) with a sequence number Seq = 2 in the cycle T2, stores the generated packet PKT1 (2) in the buffer 14, and transmits it. Output to means 18A. In addition, the coding unit 17A of the wireless device 1 reads out the packets PKT1 (1), PKT2 (1), PKT3 (1), and PKT4 (1) stored in the buffer 14 in the cycle T2, and the codes c ₁₁ , c ₁₂ , c ₁₃ , c ₁₄ , c ₁₅ , c ₁₆ are randomly generated to generate a code string FC1_1 = (c ₁₁ , c ₁₂ , c ₁₃ , c ₁₄ , c ₁₅ , c ₁₆ ).

Then, the coding unit 17A of the wireless device 1 does not receive the packets PKT5 (1) and PKT6 (1) because the receiving unit 11 cannot receive the packets PKT1 (1), PKT2 (1), PKT3 (1), PKT4 ( 1) is generated as packets P ₁₁ , P ₁₂ , P ₁₃ , and P ₁₄ , respectively, and a packet <P ₁ > = (P ₁₁ , P ₁₂ , P ₁₃ , P ₁₄ , 0, 0) is generated and the code string FC1_1 Each of the codes c ₁₅ and c ₁₆ is set to “0” to generate a code vector <c ₁ > = (c ₁₁ , c ₁₂ , c ₁₃ , c ₁₄ , 0, 0).

Then, the coding unit 17A of the wireless device 1 uses the packet <P ₁ > = (P ₁₁ , P ₁₂ , P ₁₃ , P ₁₄ , 0, 0) and the code vector <c ₁ > = (c ₁₁ , c ₁₂ , c ₁₃ , c ₁₄ , 0, 0), the coding packet <y ₁ > = (c ₁₁ , c ₁₂ , c ₁₃ , c ₁₄ , 0, 0) × (P ₁₁ , P ₁₂ , P ₁₃ , P ₁₄ , 0,0) ^T is generated.

Then, the coding unit 17A of the wireless device 1 uses the above-described method based on the code vector <c ₁ > = (c ₁₁ , c ₁₂ , c ₁₃ , c ₁₄ , 0, 0) to perform the bit string FC2_1 = (1, _{1, 1, 1} , 0, 0) and the generated bit string FC2_1 = ( _{1, 1, 1, 1,} 0, 0) and the coding packet <y ₁ > = (c ₁₁ , c ₁₂ , c ₁₃ , C ₁₄ , 0, 0) × (P ₁₁ , P ₁₂ , P ₁₃ , P ₁₄ , 0, 0) ^T is output to the transmission means 18A.

The transmission unit 18A of the wireless device 1 receives the packet PKT1 (2) from the packet generation unit 16 in the period T2, and receives the bit string FC2_1 = (1, 1, 1, 1, 0, 0) and the coding packet <from the coding unit 17A. y ₁ > = (c ₁₁ , c ₁₂ , c ₁₃ , c ₁₄ , 0, 0) × (P ₁₁ , P ₁₂ , P ₁₃ , P ₁₄ , 0, 0) ^T

Then, the transmission unit 18A of the wireless device 1 reads the packet PKT1 (1) from the buffer 14, stores the broadcast address FF in a “header”, and converts the packet PKT1 (1) into a “spontaneous packet (Seq = k)”. The packet PKT1 (2) is stored in the “spontaneous packet (Seq = k + 1)”, the bit string FC2_1 = (1, 1, 1, 1, 0, 0) is stored in the “decode information”, and the coding packet < y ₁ > = (c ₁₁ , c ₁₂ , c ₁₃ , c ₁₄ , 0, 0) × (P ₁₁ , P ₁₂ , P ₁₃ , P ₁₄ , 0, 0) ^{T is changed} to “coding packet (Seq = k)” and stores the combined packet PKT_CBB1 (2) = the [FF / PKT1 (2) / PKT1 (1) / (1,1,1,1,0,0) / (c 11, c 12, c 13, _{14, 0,0) × (P 11} , P 12, P 13, P 14, to produce a ^{0,0) T].} Thereafter, the transmission unit 18A of the wireless device 1 transmits the combined packet PKT_CBB1 (2) = [FF / PKT1 (2) / PKT1 (1) / (1,1,1,1,0,0) / () in the period T2. c ₁₁ , c ₁₂ , c ₁₃ , c ₁₄ , 0, 0) × (P ₁₁ , P ₁₂ , P ₁₃ , P ₁₄ , 0, 0) ^T ] is broadcast (see FIG. 5).

Further, in the period T2, the wireless device 2 performs the combined packet PKT_CBB2 (2) = [FF / PKT2 (2) / PKT2 (1) / (1, 1, 1, 0, 1, 1) / (c ₂₁ , c ₂₂ , c ₂₃ , 0, c ₂₅ , c ₂₆ ) × (P ₂₁ , P ₂₂ , P ₂₃ , 0, P ₂₅ , P ₂₆ ) ^T ] and the generated bond packet PKT_CBB2 (2) = [FF / PKT2 (2) / PKT2 (1) / (1,1,1,0,1,1) / (c 21, c 22, c 23, 0, c 25, c 26 ) × (P ₂₁ , P ₂₂ , P ₂₃ , 0, P ₂₅ , P ₂₆ ) ^T ] (see FIG. 5). In this case, the packets P ₂₁ , P ₂₂ , P ₂₃ , P ₂₅ , and P ₂₆ are composed of packets PKT1 (1), PKT2 (1), PKT3 (1), PKT5 (1), and PKT6 (1), respectively.

Further, in the period T2, the wireless device 3 performs the combined packet PKT_CBB3 (2) = [FF / PKT3 (2) / PKT3 (1) / (1,1,1,1,1,1) in the same manner as the wireless device 1. 1) / (c ₃₁ , c ₃₂ , c ₃₃ , c ₃₄ , c ₃₅ , c ₃₆ ) × (P ₃₁ , P ₃₂ , P ₃₃ , P ₃₄ , P ₃₅ , P ₃₆ ) ^T ] is generated and generated Combined packet PKT_CBB3 (2) = [FF / PKT3 (2) / PKT3 (1) / (1,1,1,1,1,1) / (c ₃₁ , c ₃₂ , c ₃₃ , c ₃₄ , c ₃₅ , C ₃₆ ) × (P ₃₁ , P ₃₂ , P ₃₃ , P ₃₄ , P ₃₅ , P ₃₆ ) ^T ] (see FIG. 5). In this case, the packets P ₃₁ , P ₃₂ , P ₃₃ , P ₃₄ , P ₃₅ , P ₃₆ are packet PKT 1 (1), PKT 2 (1), PKT 3 (1), PKT 4 (1), PKT 5 (1), respectively. , PKT6 (1).

Further, in the period T2, the wireless device 4 performs the combined packet PKT_CBB4 (2) = [FF / PKT4 (2) / PKT4 (1) / (1, 0, 1, 1, 1, 1) in the same manner as the wireless device 1. 1) / (c ₄₁ , 0, c ₄₃ , c ₄₄ , c ₄₅ , c ₄₆ ) × (P ₄₁ , 0, P ₄₃ , P ₄₄ , P ₄₅ , P ₄₆ ) ^T ] and the generated bond packet PKT_CBB4 (2) = [FF / PKT4 (2) / PKT4 (1) / (1,0,1,1,1,1) / (c 41, 0, c 43, c 44, c 45, c 46 ) × (P ₄₁ , 0, P ₄₃ , P ₄₄ , P ₄₅ , P ₄₆ ) ^T ] is broadcast (see FIG. 5). In this case, packets P ₄₁ , P ₄₃ , P ₄₄ , P ₄₅ , and P ₄₆ are composed of packets PKT 1 (1), PKT 3 (1), PKT 4 (1), PKT 5 (1), and PKT 6 (1), respectively.

Further, in the period T2, the wireless device 5 performs the combined packet PKT_CBB5 (2) = [FF / PKT5 (2) / PKT5 (1) / (0, 1, 1, 1, 1, 1) in the same manner as the wireless device 1. 1) / (0, c ₅₂ , c ₅₃ , c ₅₄ , c ₅₅ , c ₅₆ ) × (0, P ₅₂ , P ₅₃ , P ₅₄ , P ₅₅ , P ₅₆ ) ^T ] and the generated bond packet PKT_CBB5 (2) = [FF / PKT5 (2) / PKT5 (1) / (0,1,1,1,1,1) / (0, c 52, c 53, c 54, c 55, c 56 ) × (0, P ₅₂ , P ₅₃ , P ₅₄ , P ₅₅ , P ₅₆ ) ^T ] (see FIG. 5). In this case, packets P ₅₂ , P ₅₃ , P ₅₄ , P ₅₅ , and P ₅₆ are composed of packets PKT 2 (1), PKT 3 (1), PKT 4 (1), PKT 5 (1), and PKT 6 (1), respectively.

Further, in the period T2, the wireless device 6 performs the combined packet PKT_CBB6 (2) = [FF / PKT6 (2) / PKT6 (1) / (0, 1, 1, 1, 1, 1) in the same manner as the wireless device 1. 1) / (0, c ₆₂ , c ₆₃ , c ₆₄ , c ₆₅ , c ₆₆ ) × (0, P ₆₂ , P ₆₃ , P ₆₄ , P ₆₅ , P ₆₆ ) ^T ] and the generated bond packet PKT_CBB6 (2) = [FF / PKT6 (2) / PKT6 (1) / (0,1,1,1,1,1) / (0, c 62, c 63, c 64, c 65, c 66 ) × (0, P ₆₂ , P ₆₃ , P ₆₄ , P ₆₅ , P ₆₆ ) ^T ] (see FIG. 5). In this case, the packets P ₆₂ , P ₆₃ , P ₆₄ , P ₆₅ , P ₆₆ are composed of packets PKT 2 (1), PKT 3 (1), PKT 4 (1), PKT 5 (1), and PKT 6 (1), respectively.

  Then, the reception unit 11 of the wireless device 1 receives the combined packets PKT_CBB2 (2), PKT_CBB3 (2), and PKT_CBB4 (2) from the wireless devices 2, 3, and 4 in the period T2, respectively, and the received combined packet PKT_CBB2 (2), PKT_CBB3 (2), PKT_CBB4 (2) are output to the control means 12.

The control unit 12 of the wireless device 1 receives the combined packets PKT_CBB2 (2), PKT_CBB3 (2), PKT_CBB4 (2) from the receiving unit 11, and the combined packets PKT_CBB2 (2), PKT_CBB3 (2) and PKT_CBB4 (2) respectively. It detects that a coding packet <y ₂ >, <y ₃ >, <y ₄ > is included, and outputs combined packets PKT_CBB2 (2), PKT_CBB3 (2), PKT_CBB4 (2) to the decoding means 13A.

Upon receiving the combined packets PKT_CBB2 (2), PKT_CBB3 (2), and PKT_CBB4 (2) from the control unit 12, the decoding unit 13A of the wireless device 1 receives the coding packet <y ₁ > = (c ₁₁ , c ₁₂ , c ₁₃ , c ₁₄ , 0, 0) × (P ₁₁ , P ₁₂ , P ₁₃ , P ₁₄ , 0, 0) ^T and the sign vector <c ₁ > = (c ₁₁ , c ₁₂ , c ₁₃ , c ₁₄ , Read 0,0).

Combined packet PKT_CBB2 (2) is, PKT_CBB2 (2) = [FF / PKT2 (2) / PKT2 (1) / (1,1,1,0,1,1) / (c 21, c 22, c 23, 0, c ₂₅ , c ₂₆ ) × (P ₂₁ , P ₂₂ , P ₂₃ , 0, P ₂₅ , P ₂₆ ) ^T ], and the combined packet PKT_CBB3 (2) is PKT_CBB3 (2) = [FF / PKT3 ( 2) / PKT3 (1) / (1,1,1,1,1,1) / (c 31, c 32, c 33, c 34, c 35, c 36) × (P 31, P 32, P ₃₃ , P ₃₄ , P ₃₅ , P ₃₆ ) ^T ], and the combined packet PKT_CBB4 (2) is PKT_CBB4 (2) = [FF / PKT4 (2) / PKT4 (1) / (1,0,1,1) , 1, 1) / (c ₄₁ , 0, c ₄₃ , C ₄₄ , c ₄₅ , c ₄₆ ) × (P ₄₁ , 0, P ₄₃ , P ₄₄ , P ₄₅ , P ₄₆ ) ^T ].

Thereafter, the decoding unit 13A of the wireless device 1 transmits the bit string FC2_2 = (1, 1, 1, 0, 1, 1) from the combined packet PKT_CBB2 (2) and the coding packet <y ₂ > = (c ₂₁ , c ₂₂ , _{c 23, 0, c 25,} c 26) × (P 21, P 22, P 23, 0, P 25, P 26) is taken out and a ^T. In addition, the decoding unit 13A of the wireless device 1 transmits the bit string FC2_3 = (1, 1, 1, 1, 1, 1) from the combined packet PKT_CBB3 (2) and the coding packet <y ₃ > = (c ₃₁ , c ₃₂ , _{c 33, c 34, c 35} , c 36) × (P 31, P 32, P 33, P 34, P 35, P 36) is taken out and a ^T. Furthermore, the decoding unit 13A of the wireless device 1 starts from the combined packet PKT_CBB4 (2) with the bit string FC2_4 = (1, 0, 1, 1, 1, 1) and the coding packet <y ₄ > = (c ₄₁ , 0, c ₄₃ , c ₄₄ , c ₄₅ , c ₄₆ ) × (P ₄₁ , 0, P ₄₃ , P ₄₄ , P ₄₅ , P ₄₆ ) ^T are taken out.

Then, the decoding unit 13A of the wireless device 1 receives the code sequence FC1_2 = (c ₂₁ , c ₂₂ , c ₂₃ , c ₂₄ , c ₂₅ , c ₂₆ ) received from the wireless device 2 and held in advance, and the bit sequence FC2_2. = (1, 1, 1, 0, 1, 1), the code vector <c ₂ > = (c ₂₁ , c ₂₂ , c ₂₃ , 0, c ₂₅ , c ₂₆ ) is generated by the method described above. To do.

Similarly, the decoding unit 13A of the wireless device 1 generates a code vector <c ₃ > = (c ₃₁ , c ₃₂ , c ₃₃ , c ₃₄ , c ₃₅ , c ₃₆ ) and a code vector <c _{4> =} generates a _{(c 41, 0, c 43} , c 44, c 45, c 46).

Then, the decoding unit 13A of the wireless device 1 has received the packet P ₁₅ = PKT5 (1) and the packet P ₁₆ = PKT6 (1) in the period T1 and thus received from the wireless devices 2 to 4 Decoding information of combined packets PKT_CBB2 (2), PKT_CBB3 (3), PKT_CBB4 (2) = FC2_2 = (1,1,1,0,1,1), FC2_3 = (1,1,1,1,1,1 ), FC2_4 = (1, 0, 1, 1, 1, 1), the packet P ₅ = PKT ₅ (1) and the packet P ₆ = PKT ₆ (1) that the reception unit 11 could not receive in the period T1 The coding packet having the information of coding packet <y ₂ > = (c ₂₁ , c ₂₂ , c ₂₃ , 0, c ₂₅ , c ₂₆ ) × (P ₂₁ , P ₂₂ , P ₂₃ , 0, P ₂₅ , P ₂₆ ) ^T , <y ₃ > = (c ₃₁ , c ₃₂ , c ₃₃ , c ₃₄ , c ₃₅ , c ₃₆ ) × (P ₃₁ , P ₃₂ , P ₃₃ , P ₃₄ , P ₃₅ , P ₃₆ ) ^T , <y ₄ > = (c ₄₁ , 0, c ₄₃ , c ₄₄ , c ₄₅ , c ₄₆ ) × (P ₄₁ , 0, P ₄₃ , P ₄₄ , P ₄₅ , P ₄₆ ) Select from ^T.

In this case, each of the coding packets <y ₂ >, <y ₃ >, <y ₄ > has information of packet P ₅ = PKT5 (1) and packet P ₆ = PKT6 (1), and There are two packets that the receiving means 11 could not receive in the period T1, packet P ₅ = PKT5 (1) and packet P ₆ = PKT6 (1).

Accordingly, the decoding unit 13A of the wireless device 1 selects any two coding packets from the coding packets <y ₂ >, <y ₃ >, and <y ₄ >. In this case, it is assumed that the decoding unit 13A of the wireless device 1 selects _two coding packets <y ₂ > and <y ₃ >.

Then, the decoding unit 13A of the wireless device 1 uses the packets P ₁ = PKT1 (1), P ₂ = PKT2 (1), P ₃ = PKT3 (1), and P ₄ = PKT4 (1) stored in the buffer 14. The read packet P ₁ = PKT1 (1), P ₂ = PKT2 (1), P ₃ = PKT3 (1), P ₄ = PKT4 (1), and coding packet <y ₂ >, <y ₃ > , <Y ₄ > and code vector <c ₂ > = (c ₂₁ , c ₂₂ , c ₂₃ , 0, c ₂₅ , c ₂₆ ), <c ₃ > = (c ₃₁ , c ₃₂ , c ₃₃ , c ₃₄ , C ₃₅ , c ₃₆ ), <c ₄ > = (c ₄₁ , 0, c ₄₃ , c ₄₄ , c ₄₅ , c ₄₆ ) and packets using the above-described equations (5) and (6) _{P 1, P 2, P 3} , P 4, the P 5, _{P 6} Code.

Then, the decoding unit 13A of the wireless device 1 obtains the packet P ₅ = PKT5 (1) and the packet P ₆ = PKT6 (1).

  Then, the decoding means 13A of the wireless device 1 performs packet PKT2 (2), PKT2 (1), packet PKT3 (2), PKT3 (1) from the combined packets PKT_CBB2 (2), PKT_CBB3 (2), PKT_CBB4 (2), respectively. , And packets PKT4 (2) and PKT4 (1), and the extracted packets PKT2 (2) and PKT2 (1); PKT3 (2) and PKT3 (1); PKT4 (2) and PKT4 (1); The decoded packets PKT5 (1) and PKT6 (1) are output to the reproducing means 15.

  If the reproduction unit 15 of the wireless device 1 has already reproduced the packets PKT2 (1), PKT3 (1), and PKT4 (1) in the period T1, the packets PKT2 (2), PKT3 (2), and PKT4 The data of (2), PKT5 (1), and PKT6 (1) are reproduced and given to the operator of the wireless device 1 as visual information.

  On the other hand, the reproducing unit 15 of the wireless device 1 does not reproduce the packets PKT2 (1), PKT3 (1), and PKT4 (1) in the period T1, and the packets PKT2 (2), PKT3 (2), PKT4 ( 2), PKT2 (1), PKT3 (1), PKT4 (1), PKT5 (1), and PKT6 (1) data are reproduced and given to the operator of the wireless apparatus 1 as visual information.

  Further, since the wireless device 2 has not received the packet PKT4 (1) from the wireless device 4 in the period T1, the combined packets PKT_CBB1 (2), PKT_CBB3 (2), PKT_CBB5 (2) are similar to the wireless device 1. ), PKT_CBB6 (2), the packet PKT4 (1) is acquired. Then, the wireless device 2 reproduces the data of the packets PKT1 (2), PKT3 (2), PKT4 (1), PKT5 (2), and PKT6 (2).

  Further, since the wireless device 4 has not received the packet PKT2 (1) from the wireless device 2 in the period T1, the combined packets PKT_CBB1 (2), PKT_CBB3 (2), PKT_CBB5 (2) are similar to the wireless device 1. ), PKT_CBB6 (2), the packet PKT2 (1) is acquired. Then, the wireless device 4 reproduces the data of the packets PKT1 (2), PKT2 (1), PKT3 (2), PKT5 (2), and PKT6 (2).

  Further, since the wireless device 5 has not received the packet PKT1 (1) from the wireless device 1 in the period T1, the combined packets PKT_CBB2 (2), PKT_CBB3 (2), PKT_CBB3 (2) are similar to the wireless device 1. ), PKT_CBB4 (2), PKT_CBB6 (2), the packet PKT1 (1) is acquired. Then, the wireless device 5 reproduces the data of the packets PKT1 (1), PKT2 (2), PKT3 (2), PKT4 (2), and PKT6 (2).

  Furthermore, since the wireless device 6 has not received the packet PKT1 (1) from the wireless device 1 in the period T1, the combined packets PKT_CBB2 (2), PKT_CBB3 (2), PKT_CBB4 (2) are received in the same manner as the wireless device 1. ), PKT_CBB5 (2), the packet PKT1 (1) is acquired. Then, the wireless device 6 reproduces the data of the packets PKT1 (1), PKT2 (2), PKT3 (2), PKT4 (2), and PKT5 (2), respectively.

  The wireless device 3 receives all of the packets PKT1 (1), PKT2 (1), PKT4 (1), PKT5 (1), and PKT6 (1) in the period T1, and therefore decodes the coding packet. Don't do it. Then, the wireless device 3 reproduces the data of the packets PKT1 (2), PKT2 (2), PKT4 (2), PKT5 (2), and PKT6 (2).

  Thereafter, the wireless devices 1 to 6 generate combined packets PKT_CBB1 (3) to PKT_CBB6 (3), respectively, in the period T3 by the method described above, and generate the generated combined packets PKT_CBB1 (3) to PKT_CBB6 (3). Broadcast (see FIG. 6).

  Then, the wireless device 1 receives and reproduces the packets PKT2 (3), PKT3 (3), PKT4 (3), PKT5 (2), and PKT6 (2) in the period T3 by the method described above. Further, the wireless device 2 receives and reproduces the packets PKT1 (3), PKT3 (3), PKT4 (2), PKT5 (3), and PKT6 (3) in the period T3 by the method described above. Further, in the period T3, the wireless device 3 receives and reproduces the packets PKT1 (3), PKT2 (3), PKT4 (3), PKT5 (3), and PKT6 (3) by the method described above. Further, the wireless device 4 receives and reproduces the packets PKT1 (3), PKT2 (2), PKT3 (3), PKT5 (3), and PKT6 (3) in the period T3 by the method described above. Further, the wireless device 5 receives and reproduces the packets PKT1 (2), PKT2 (3), PKT3 (3), PKT4 (3), and PKT6 (3) in the period T3 by the method described above. Further, the wireless device 6 receives and reproduces the packets PKT1 (2), PKT2 (3), PKT3 (3), PKT4 (3), and PKT5 (3) in the period T3 by the above-described method (FIG. 6). reference).

  As described above, in the second embodiment, the wireless devices 1 to 6 generate the packet PKT (k) generated in the kth cycle and the k + 1th cycle in the k + 1th cycle. Since the combined packet PKT_CBB including the packet PKT (k + 1) and the coding packet PKT_cd is generated and broadcast, even if the packet PKT (k) cannot be correctly received due to packet collision in the kth period, the k + 1th In the period, the packet PKT (k) can be correctly received and reproduced.

  Therefore, according to the present invention, the packet arrival rate to the transmission destination can be improved.

  In addition, Embodiment 2 can enjoy the same effects as Embodiment 1.

  In the first and second embodiments described above, when the coding unit 17 generates a coding packet, it corresponds to a packet that is not actually received by the reception unit 11 in both the code vector <c> and the packet <P>. In the embodiment of the present invention, the coding unit 17 is not limited to this, and the coding unit 17 receives the reception unit 11 in at least one of the code vector <c> and the packet <P>. However, an element corresponding to a packet that is not actually received may be set to “0” to generate a coding packet.

  In the embodiment of the present invention, packet <P> constitutes a “packet matrix”.

In the present invention, the code sequence randomly generated from the Galois field (GF2 ^j ) constitutes a “random code sequence”.

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is shown not by the above description of the embodiments but by the scope of claims for patent, and is intended to include meanings equivalent to the scope of claims for patent and all modifications within the scope.

  The present invention is applied to a radio apparatus capable of improving the arrival rate of packets while maintaining the immediacy of arrival of packets to a transmission destination. Further, the present invention is applied to a radio apparatus capable of performing error correction efficiently in an environment where link quality dynamically changes. Furthermore, this is applied to a wireless network including a wireless device capable of improving the arrival rate of packets while maintaining the immediacy of arrival of packets to the transmission destination. Furthermore, the present invention is applied to a wireless network including a wireless device capable of efficient error correction in an environment where link quality dynamically changes.

1 is a schematic diagram of a wireless network according to an embodiment of the present invention. FIG. 2 is a schematic block diagram illustrating a configuration of the wireless device illustrated in FIG. 1 according to the first embodiment. It is a block diagram in Embodiment 1 of the combined packet which combined the spontaneous packet and the coding packet. It is a 1st conceptual diagram for demonstrating the communication method in the radio | wireless network shown in FIG. FIG. 3 is a second conceptual diagram for explaining a communication method in the wireless network shown in FIG. 1. FIG. 4 is a third conceptual diagram for explaining a communication method in the wireless network shown in FIG. 1. 2 is a timing chart of wireless communication in the wireless network shown in FIG. It is a figure which shows the relationship between an average packet error rate and the number of radio | wireless apparatuses. It is a figure which shows the relationship between the maximum packet error rate and the number of radio | wireless apparatuses. FIG. 3 is a schematic block diagram illustrating a configuration of a wireless device illustrated in FIG. 1 in a second embodiment. It is a block diagram in Embodiment 2 of the combined packet which combined the spontaneous packet and the coding packet.

Explanation of symbols

  1 to 6 wireless devices, 10 wireless networks, 11 receiving means, 12 control means, 13, 13A decoding means, 14 buffers, 15 reproducing means, 16 packet generating means, 17, 17A coding means, 18, 18A transmitting means.

Claims (9)

A wireless device constituting a wireless network that periodically transmits and receives packets,
N (n is an integer satisfying 1 ≦ n ≦ N−1) packets from N−1 wireless devices out of N (N is an integer of 2 or more) wireless devices constituting the wireless network. receiving means for receiving in the k-th period (k is a positive integer);
Coding means for network-coding the n packets received by the receiving means using a randomly generated random code sequence;
Packet generation means for periodically generating a spontaneous packet for transmission;
A coding packet network-coded in the (k + 1) th period by the coding means; the spontaneous packet generated in the (k + 1) th period by the packet generating means; and decoding information for decoding the coding packet. And a transmitting unit that generates a combined packet including the broadcast packet and broadcasts the generated combined packet in the (k + 1) th period.   Decoding means for receiving the combined packet broadcast from another radio apparatus from the receiving means, extracting the decoding information and the coding packet from the received combined packet, and decoding the coding packet using the extracted decoding information The wireless device according to claim 1, further comprising: The coding means generates a code vector composed of N codes constituting the random code string, and includes N-1 packets transmitted from the N-1 radio apparatuses and the spontaneous packets. A packet matrix is generated, and in at least one of the generated code vector and the packet matrix, an element corresponding to a packet not received by the receiving unit is set to zero and the code vector and the packet matrix are multiplied Network coding by
The transmission means generates and broadcasts the combined packet including the decoding information composed of the code vector,
The radio apparatus according to claim 2, wherein the decoding unit extracts the decoding information including the code vector and the coding packet from the combined packet, and decodes the coding packet using the extracted code vector. The coding means generates a code vector composed of N codes constituting the random code string, and includes N-1 packets transmitted from the N-1 radio apparatuses and the spontaneous packets. A packet matrix is generated, and in at least one of the generated code vector and the packet matrix, an element corresponding to a packet not received by the receiving unit is set to zero and the code vector and the packet matrix are multiplied Network coding by
The transmitting unit generates the combined packet including the decoding information including a bit string indicating whether or not the receiving unit has actually received N-1 packets transmitted from the N-1 wireless devices. Broadcast
The decoding means extracts the decoding information consisting of the bit string and the coding packet from the combined packet, multiplies the extracted bit string and the random code string held in advance to obtain the code vector, The radio apparatus according to claim 2, wherein the coding packet is decoded using the obtained code vector. The packet generation means generates a first spontaneous packet in the k-th cycle, generates a second spontaneous packet in the k + 1-th cycle,
The transmission means generates a combined packet including a coding packet network-coded in the k + 1 th cycle by the coding means, first and second spontaneous packets by the packet generation means, and the decoding information. The radio apparatus according to claim 1, wherein the generated combined packet is broadcast in the (k + 1) th period. A wireless network in which packets are transmitted and received periodically,
N (N is an integer of 2 or more) wireless devices,
The N wireless devices are:
N (n is an integer satisfying 1 ≦ n ≦ N−1) packets are received from N−1 wireless devices in the k-th (k is a positive integer) period, and the received n packets Are network-coded in the (k + 1) -th cycle using a randomly generated random code sequence, and a spontaneous packet for transmission in the (k + 1) -th cycle is generated, and the network-coded coding packet and the spontaneous A first wireless device that generates a combined packet including a packet and decoding information for decoding the coding packet, and broadcasts the generated combined packet in the k + 1-th period;
Receiving a combined packet broadcast from the first wireless device, extracting the spontaneous packet, the coding packet, and the decoding information from the received combined packet, and decoding the coding packet using the extracted decoding information And a second wireless device. The first radio apparatus generates a code vector composed of N codes constituting the random code sequence, and N-1 packets and the spontaneous packets transmitted from the N-1 radio apparatuses. And at least one of the generated code vector and the packet matrix, the element corresponding to the packet not received by the receiving means is set to zero, and the code vector and the packet matrix And the network-coded coding packet, the decoding information including the code vector, and the spontaneous packet are generated and broadcast in the (k + 1) th period. And
The second radio apparatus extracts the decoding information including the code vector, the coding packet, and the spontaneous packet from the combined packet, and decodes the coding packet using the extracted code vector. A wireless network as described in. The first radio apparatus generates a code vector composed of N codes constituting the random code sequence, and N-1 packets and the spontaneous packets transmitted from the N-1 radio apparatuses. And at least one of the generated code vector and the packet matrix, the element corresponding to the packet not received by the receiving means is set to zero, and the code vector and the packet matrix And the network coding coding packet and a bit string indicating whether or not N-1 packets transmitted from the N-1 radio apparatuses are actually received. Generate the combined packet including the decoding information and the spontaneous packet Broadcast in the first (k + 1) th cycle Te,
The second radio apparatus extracts the decoding information composed of the bit string, the coding packet, and the spontaneous packet from the combined packet, and multiplies the extracted bit string and the random code string held in advance. The wireless network according to claim 6, wherein the code vector is obtained and the coding packet is decoded using the obtained code vector. The first radio apparatus generates first and second spontaneous packets in the k-th cycle and the k + 1-th cycle, respectively, and the generated first and second spontaneous packets; generating a combined packet including a network-coded coding packet in the (k + 1) th period and the decoding information, and broadcasting the generated combined packet in the (k + 1) th period;
The second wireless device receives the combined packet broadcast from the first wireless device, extracts the first and second spontaneous packets, the coding packet, and the decoding information from the received combined packet. The wireless network according to claim 6, wherein the coding packet is decoded using the extracted decoding information.

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