JP2022116618A - Transmitter, receiver, wireless communication system equipped therewith, program, and computer readable recording medium in which program is recorded - Google Patents

Abstract

To provide a transmitter capable of transmitting, in a low delay mode, a plurality of packets constituting a burst.SOLUTION: When one N packet arrives at a transmitter 1, processing means 12 copies the N packet to a buffer 11 and transmits it via transmission means 13 and an antenna 14. When a prescribed N packet selected from (MBurst-1) pieces of N packet, other than the N packet having arrived first, among MBurst pieces of N packet constituting a burst arrives at the transmitter 1, the processing means 12 transmits, via the transmission means 13 and the antenna 14, a combined packet in which encoded packets including the N packet having arrived before the prescribed N packet are added to the prescribed N packet. When it is determined that the last N packet among MBurst pieces of N packet has arrived at the transmitter 1, an encoded packet in which MBurst pieces of N packet are encoded is transmitted via the transmission means 13 and the antenna 14.SELECTED DRAWING: Figure 2

Description

The present invention relates to a transmitting device, a receiving device, a wireless communication system provided with these devices, a program, and a computer-readable recording medium recording the program.

Non-Patent Document 1 discloses transmitting a plurality of packets through a plurality of routes when a plurality of packets to be transmitted are ready.

In addition, Non-Patent Document 2 discloses trying to reduce the delay by transmitting a plurality of packets while sliding a window over the plurality of packets when a plurality of packets to be transmitted are available.

Furthermore, Patent Literature 1 discloses that in many-to-many communication, a plurality of packets are network-coded, and the network-coded coded packets are broadcast to improve the packet delivery rate.

More specifically, the wireless devices TM_1 to TM_6 respectively generate and broadcast single packets PKT1(1) to PKT6(1) with sequence number Seq=1 in the first period. After that, in the second cycle, the wireless devices TM_1 to TM_6 generate a coded packet obtained by network coding the packets PKT1(1) to PKT6(1) with the sequence number Seq=1 and a single packet with the sequence number Seq=2. generates and broadcasts a combined packet of Furthermore, in the third period, the wireless devices TM_1 to TM_6 generate a coding packet obtained by network coding the packets PKT1(2) to PKT6(2) with the sequence number Seq=2 and a single packet with the sequence number Seq=3. generates and broadcasts a combined packet of The wireless devices TM_1 to TM_6 repeat this process.

Thus, Patent Document 1 discloses that each of the wireless devices TM_1 to TM_6 performs network coding on packets generated by itself and packets received from other wireless devices to generate coded packets. In other words, Patent Literature 1 discloses network-coding a plurality of packets to generate a coded packet when the packets to be network-coded are known.

JP 2010-093738 A

https://ieeexplore.ieee.org/stamp/stamp.jsp?arnumber=5753567&casa_token=NlznD3EhwnsAAAA:GxTWt9heKzlvg0G6nUoIhPijCKnV26EoCsg0jRrjm7ZFijLql TaT7s_IXCxZ4H7bK8IfHn-nQA https://ieeexplore.ieee.org/stamp/stamp.jsp?arnumber=88267 10&casa_token=zouNIPn0UqgAAAA:aoV6VQxo79INnWaVIlTKDcxSkeH_nrWGEnZxVxbZYgxRlUaY899uw4fe9yeW-P-MmdxEFHu5QQ

However, the communication methods described in Non-Patent Documents 1 and 2 are methods of processing after waiting for the arrival of a plurality of packets. If you send by , there will be a delay.

In addition, since the start and/or end of a burst cannot be known, the method described in Patent Document 1 makes it difficult to efficiently perform network coding of packets.

Therefore, according to the embodiments of the present invention, there is provided a transmission device capable of transmitting a plurality of packets forming a burst with low delay.

Further, according to the embodiments of the present invention, there is provided a receiving device for receiving packets from a transmitting device capable of transmitting a plurality of packets forming a burst with low delay.

Furthermore, according to the embodiment of the present invention, a transmission device capable of transmitting a plurality of packets constituting a burst with low delay and receiving packets from the transmission device capable of transmitting a plurality of packets constituting a burst with low delay A wireless communication system comprising a receiving device for

Furthermore, according to the embodiment of the present invention, there is provided a program for causing a computer to transmit a plurality of packets forming a burst with low delay.

Furthermore, according to an embodiment of the present invention, there is provided a program for causing a computer to receive packets transmitted by low-delay transmission of a plurality of packets forming a burst.

Furthermore, according to an embodiment of the present invention, there is provided a computer-readable recording medium recording a program for causing a computer to transmit a plurality of packets forming a burst with low delay.

Furthermore, according to an embodiment of the present invention, there is provided a computer-readable recording medium recording a program for causing a computer to receive packets transmitted by low-delay transmission of a plurality of packets forming a burst. do.

(Configuration 1)
According to an embodiment of the present invention, a transmission device receives packets constituting real-time traffic from an application and transmits the received packets, and comprises a transmission buffer, processing means, and transmission means. and The transmission buffer is a buffer for storing transmission packets. The processing means executes processing for transmission on the packet. The transmitting means transmits the packet received from the processing means. Then, when the packet is the first single packet arriving at the transmitting device at the first time interval, the processing means stores the first single packet in the transmission buffer when the first single packet arrives at the transmitting device. and outputting the first single packet to the transmitting means, and the packets arrive at the transmitting device continuously at a second time interval shorter than the first time interval. When a single packet is a single packet, when a second single packet selected from single packets other than the single packet that arrived at the transmitting device first among a plurality of single packets arrives at the transmitting device, the second single packet is sent to the transmitting device. means for generating a combined packet in which a first encoded packet including a single packet copied to a transmission buffer and arriving at the transmitting apparatus earlier than the second single packet is added to the second single packet, and for transmitting the combined packet; When a third simple packet that is included in a plurality of simple packets and is a single packet other than the second simple packet arrives at the transmitting device, the third simple packet , and when it is determined that the last single packet of the plurality of single packets has arrived at the transmitting device, the last single packet is copied to the transmission buffer, and the last single packet is transferred to the first When the last single packet corresponds to the second single packet, the second processing is performed on the last single packet, and when the last single packet corresponds to the third single packet, the first processing is performed on the last single packet. Then, when a predetermined time elapses from the timing at which it is determined that the last single packet has arrived at the transmitting device, a second encoded packet including all the single packets stored in the transmission buffer is generated and sent to the transmitting means. Execute the third process of outputting. Further, when the transmission means receives the first single packet from the processing means, the transmission means executes the first transmission process of transmitting the received first single packet alone, and when the combined packet is received from the processing means, the When a second transmission process for transmitting the received combined packet is executed, and a third single packet or the last single packet is received from the processing means, a third single packet or the last single packet is sent to the received third single packet or the last single packet. When the first transmission process is executed and the second encoded packet is received from the processing means, the third transmission process of transmitting the received second encoded packet alone is executed.

(Configuration 2)
In configuration 1, the processing means is, in the second processing, the single packet that arrived at the transmission device last among the single packets that arrived at the transmission device earlier than the second single packet or the last single packet. When the fourth simplex packet arrives at the transmitting device, it includes simplex packets that arrived at the transmitting device earlier than the second simplex packet or the last simplex packet after the fourth simplex packet was transmitted by the transmitting means. A first sub-process for generating a first encoded packet is executed, and when the second simplex packet or the last simplex packet arrives at the transmitting device after the first sub-process is executed, the first code is A second sub-process is executed for adding the combined packet to the second single packet or the last single packet to generate a combined packet and output the combined packet to the transmitting means.

(Composition 3)
In configuration 2, the processing means, in the second processing, when the second unitary packet consists of a unitary packets (a is an integer equal to or greater than 1), for each of the a unitary packets, Execute the first and second sub-processes.

(Composition 4)
In any one of configuration 1 to configuration 3, the processing means sets the initial value of the encoded packet to Y ₀ consisting of a predetermined length of zeros, and sets the packet extracted from the transmission buffer to X _i (i=1, 2, . . . ). , I, I are the total number of packets stored in the transmission buffer when generating the first encoded packet or the second encoded packet), a random number of a predetermined length is _Ci , and encoding Assuming that the packet is Y _i , the XOR operation of the multiplication result C _i ·X _i obtained by multiplying the packet X _i by a random number C _i of a predetermined length and Y _i−1 is executed for all i The resulting encoded packet _Yi is generated as a first encoded packet or a second encoded packet.

(Composition 5)
In any one of configurations 1 to 4, the transmitting device further includes a plurality of base stations. A plurality of base stations are connected by transmission means and wired cables. Then, the plurality of base stations receive the first single packet, the combined packet, the third single packet, the last single packet, and the second encoded packet from the transmission means via the wired cable, and The first simple packet, the combined packet, the third simple packet, the last simple packet and the second encoded packet are transmitted through mutually different communication paths.

(Composition 6)
Further, according to an embodiment of the present invention, a receiving device is a receiving device for receiving a packet from the transmitting device according to any one of configurations 1 to 5, comprising: a first reception buffer; It comprises a receiving buffer, receiving means, separating means, first processing means, second processing means, and decoding means. The first receive buffer is a buffer for storing single packets. The second receive buffer is a buffer for storing encoded packets. The receiving means receives the first and third simple packets, the combined packet and the second encoded packet. Separating means separates the combined packet into a first encoded packet and a second single packet. The first processing means stores, in the first reception buffer, a single packet that has not been stored in the first reception buffer or has not been received among the first single packet or the third single packet. A reception process is executed to transmit the single packet stored in the reception buffer 1 from the transmission device to the application that uses the information transmitted by the packet. The second processing means generates a third encoded packet containing only a plurality of single packets not stored in the first reception buffer based on the encoded packet received by the receiving means, and A process of storing the third encoded packet in the second receive buffer is performed for all of the first and second encoded packets. The decoding means reads the plurality of third encoded packets from the second reception buffer, solves simultaneous equations for the read plurality of third encoded packets, and decodes the plurality of third encoded packets. Execute the decryption process. Then, the first processing means further performs reception processing on the single packet decoded by the decoding means.

(Composition 7)
In configuration 6, the second processing means generates the third encoded packet by removing the information of the single packet stored in the first reception buffer from the encoded packet received by the receiving means.

(Composition 8)
In configuration 7, when the second processing means determines that the single packet stored in the first reception buffer is included in the encoded packet received by the receiving means, the encoded packet received by the receiving means Generate a third encoded packet.

(Composition 9)
In configuration 7 or configuration 8, the second processing means removes the information of the single packet stored in the first reception buffer from the encoded packet received by the receiving means, and converts the encoded packet into one single packet. When the packet is included, the coded packet including one single packet is also deleted from the second receive buffer. The first processing means converts an encoded packet including one single packet into a single packet, and performs reception processing on the converted single packet.

(Configuration 10)
In any one of configurations 6 to 9, the receiving device further includes a plurality of base stations. A plurality of base stations are connected to the receiving means by wired cables, and receive packets transmitted from the transmitting device via a plurality of mutually different communication paths. Then, each of the plurality of base stations outputs the received packets to the receiving means via wired cables.

(Composition 11)
Further, according to an embodiment of the present invention, a radio communication system includes the transmitting device according to any one of configurations 1 to 5 and the receiving device according to any one of configurations 6 to 10.

(Composition 12)
Furthermore, according to the embodiment of the present invention, the program is a program for causing a computer to transmit packets in a transmission device that receives packets constituting real-time traffic from an application,
a first step in which the processing means performs processing for transmission on the packet;
causing the computer to perform a second step in which the transmitting means transmits the packet received from the processing means;
In the first step, when the packet is the first single packet arriving at the transmitting device at the first time interval, the processing means stores the packet for transmission when the first single packet arrives at the transmitting device. performing a first process of copying the first simple packet to a transmission buffer for transmitting and outputting the first simple packet to the transmitting means, wherein the packet is transmitted at a second time interval shorter than the first time interval; When a plurality of single packets arrive at the transmitting device in succession, a second single packet selected from single packets other than the single packet arriving at the transmitting device first among the plurality of single packets arrives at the transmitting device. Then, the second single packet is copied to the transmission buffer, and a combined packet is generated by adding the first encoded packet including the single packet that arrived at the transmitting device earlier than the second single packet to the second single packet. Then, a second process of outputting the combined packet to the transmitting means is executed, and when a third single packet which is included in the plurality of single packets and which is a single packet other than the second single packet arrives at the transmitting device. , performs the first processing on the third single packet, and if it is determined that the last single packet of the plurality of single packets has arrived at the transmitting device, copies the last single packet to the transmission buffer, and corresponds to the second simple packet, the last simple packet is subjected to the second processing, and when the last simple packet corresponds to the third simple packet, the last simple packet is subjected to the 1, and when a predetermined time elapses from the timing at which it is determined that the last single packet has arrived at the transmission device, a second encoded packet including all single packets stored in the transmission buffer is generated. and executing a third process of outputting to the transmitting means,
In the second step, the transmitting means, when receiving the first single packet from the processing means, executes a first transmission process for transmitting the received first single packet alone, and transmits the combined packet from the processing means. When receiving, the second transmission processing for transmitting the received combined packet is executed, and when the third single packet or the last single packet is received from the processing means, the third single packet or the last single packet is received. When the second encoded packet is received from the processing means, the third transmission processing is carried out for transmitting the received second encoded packet alone.

(Composition 13)
In configuration 12, the processing means, in the second processing of the first step,
When a fourth simplex packet, which is the last simplex packet among the simplex packets arriving at the transmitting apparatus earlier than the second simplex packet or the last simplex packet, arrives at the transmitting apparatus, the fourth simplex packet arrives at the transmitting apparatus. performing a first sub-process of generating a first encoded packet including a simplex packet that arrived at the transmitting device earlier than the second simplex packet or the last simplex packet after the packet was transmitted by the transmitting means; After executing the first sub-process, when the second simple packet or the last simple packet arrives at the transmitting device, the first encoded packet is added to the second simple packet or the last simple packet to generate a combined packet. is generated and output to the transmitting means.

(Composition 14)
In configuration 13, in the second processing of the first step, when the second simple packet consists of a (a is an integer equal to or greater than 1) simple packet, a simple packet For each packet, first and second sub-processes are performed.

(Composition 15)
In any one of configuration 12 to configuration 14, the processing means sets the initial value of the encoded packet to Y ₀ consisting of zeros of a predetermined length, and sets the packet extracted from the transmission buffer to X _i (i=1, 2, . . . ). , I, I are the total number of packets stored in the transmission buffer when generating the first encoded packet or the second encoded packet), a random number of a predetermined length is _Ci , and encoding Assuming that the packet is Y _i , the XOR operation of the multiplication result C _i ·X _i obtained by multiplying the packet X _i by a random number C _i of a predetermined length and Y _i−1 is executed for all i The resulting encoded packet _Yi is generated as a first encoded packet or a second encoded packet.

(Composition 16)
In any of configurations 12 to 14, the transmitting means, in the second step, transmits the first simplex packet, the combined packet, the third simplex packet, the last simplex packet and the second code over the wired cable. to multiple base stations,
The plurality of base stations receive the first simple packet, the combined packet, the third simple packet, the last simple packet and the second encoded packet from the transmission means via the wired cable, and transmit the received first packet. The simplex packet, the combined packet, the third simplex packet, the last simplex packet and the second encoded packet are transmitted through mutually different communication paths.

(Composition 17)
Further, according to the embodiment of the present invention, the program is a program for causing a computer to receive packets transmitted by causing a computer to execute the program according to any one of configurations 12 to 16. hand,
a first step in which the receiving means receives the first and third simplex packets, the combined packet and the second encoded packet;
a second step in which the separating means separates the combined packet into a first encoded packet and a second simple packet;
The first processing means stores in the first reception buffer a single packet that has not been stored in the first reception buffer or has not been received among the first single packet or the third single packet, and stores the single packet in the first reception buffer. a third step of performing a receiving process of transmitting the single packet stored in one receive buffer to an application that utilizes the information transmitted by the packet;
a second processing means for generating a third encoded packet containing only a plurality of single packets not stored in the first reception buffer based on the encoded packet received in the first step; a fourth step of storing the generated third encoded packet in the second reception buffer for all of the first and second encoded packets;
A decoding means reads the plurality of third encoded packets from the second reception buffer, solves simultaneous equations for the read plurality of third encoded packets, and decodes the plurality of third encoded packets. causing a computer to perform a fifth step of performing a decryption process;
The first processing means further performs reception processing on the single packet decoded by the decoding means in the third step.

(Composition 18)
In configuration 17, the second processing means, in the fourth step, removes the information of the single packet stored in the first reception buffer from the encoded packet received in the first step, thereby generating the third Generate encoded packets.

(Composition 19)
In configuration 18, when the second processing means determines in the fourth step that the single packet stored in the first reception buffer is included in the encoded packet received in the first step, the first generate a third encoded packet from the encoded packet received in step a.

(Composition 20)
In configuration 18 or configuration 19, the second processing means removes, in the fourth step, the information of the single packet stored in the first reception buffer from the encoded packet received in the first step. when the encoded packet includes one simplex packet, further deleting the encoded packet including the single simplex packet from the first receive buffer;
In the third step, the first processing means converts an encoded packet including one single packet into a single packet, and performs reception processing on the converted single packet.

(Composition 21)
Further, according to the embodiment of the present invention, the recording medium is a computer-readable recording medium recording the program according to any one of structures 12 to 20.

Multiple packets that make up a burst can be transmitted with low delay.

1 is a schematic diagram of a wireless communication system according to embodiments of the invention; FIG. 2 is a schematic diagram of the transmitter shown in FIG. 1; FIG. 2 is a schematic diagram of the receiver shown in FIG. 1; FIG. FIG. 4 is a conceptual diagram showing image transmission; FIG. 4 is a schematic diagram showing the format of a packet; Figure 3 is a schematic diagram of the buffer shown in Figure 2; FIG. 4 is a diagram for explaining a method of encoding packets; FIG. FIG. 4 is a diagram illustrating a method of generating encoded packets when transmitting M _Burst packets PKT_N(1) to PKT_N(M _Burst ); FIG. 4 is a diagram for explaining a method of transmitting packets that form a burst; FIG. FIG. 10 is a diagram for explaining another method of transmitting packets forming a burst; FIG. FIG. 10 is a diagram for explaining still another method of transmitting packets forming a burst; FIG. 3 is a flow chart for explaining the operation of the transmitter shown in FIGS. 1 and 2; FIG. FIG. 13 is a flow chart for explaining the detailed operation of step S8 shown in FIG. 12; FIG. FIG. 4 is a flow chart for explaining the operation of the receiver shown in FIGS. 1 and 3; FIG. FIG. 15 is a flow chart for explaining the detailed operation of step S26 shown in FIG. 14; FIG. FIG. 15 is a flow chart for explaining the detailed operation of step S28 shown in FIG. 14; FIG. FIG. 15 is a flow chart for explaining the detailed operation of step S29 shown in FIG. 14; FIG. FIG. 10 is a diagram showing the transition of the N-buffer and the C-buffer when receiving packets forming a burst; 4 is a schematic diagram of another wireless communication system according to embodiments of the invention; FIG. FIG. 4 is a schematic diagram of yet another wireless communication system according to embodiments of the invention; FIG. 4 is a schematic diagram of yet another wireless communication system according to embodiments of the invention; 2 is a diagram showing another application example of the wireless communication system shown in FIG. 1; FIG.

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

FIG. 1 is a schematic diagram of a wireless communication system according to an embodiment of the invention. Referring to FIG. 1, radio communication system 10 according to the embodiment of the present invention comprises transmitter 1 and receiver 2 . A transmitter 1 and a receiver 2 are placed in a wireless communication space.

The application 20 captures an image with a camera, for example, and transmits to the transmitter 1 a packet PKT including image data of the captured image in its payload.

The transmitter 1 receives packets PKT from the application 20 . Then, the transmitter 1 transmits the packet PKT as a packet constituting real-time traffic to the receiver 2 by wireless communication by a method to be described later.

The receiver 2 receives the packet PKT from the transmitter 1 by wireless communication, and executes reception processing, which will be described later, on the received packet PKT. The receiver 2 then transmits the received packet PKT to the application 30 . The application 30 receives the packet PKT from the receiver 2, reproduces the image data included in the received packet PKT, and displays it on the display unit.

The wireless communication system 10 has the following features. The wireless communication system 10 is a system incapable of efficient retransmission using arrival confirmation, and performs broadcast or multicast by wireless communication, for example. Also, the wireless communication system 10 is a system that uses multiple routes. Furthermore, the wireless communication system 10 performs real-time communication (for example, video transmission, etc.) that requires high reliability.

FIG. 2 is a schematic diagram of the transmitter 1 shown in FIG. Referring to FIG. 2, transmitter 1 comprises buffer 11 , processing means 12 , transmitting means 13 and antenna 14 .

Buffer 11 stores a plurality of packets PKT_N( 1 ) to PKT_N(V) arriving from application 20 . Each of the plurality of packets PKT_N( 1 ) to PKT_N(V) consists of native packets generated by the application 20 . Also, V consists of an integer.

The processing means 12 incorporates a timer. Then, the processing means 12 determines whether or not the packet has arrived. Then, when the processing means 12 determines that a packet has arrived, the processing means 12 stores a copy of the arrived packet PKT_N(v) (v is an integer from 1 to V) in the buffer 11, and restores the original packet PKT_N(v). Output to the transmission means 13 . If a plurality of packets are stored in the buffer 11 when the processing means 12 determines that packets have arrived, the processing means 12 retrieves the plurality of packets from the buffer 11, and performs a method described later based on the retrieved plurality of packets. generates a transmission packet PKT_TR including the encoded packet PKT_C, and outputs the generated transmission packet PKT_TR to the transmission means 13 . Note that the processing means 12 outputs the packet PKT_N(v) or the transmission packet PKT_TR to the transmission means 13 with reference to the timer.

Upon receiving one packet PKT_N(v) or transmission packet PKT_TR from the processing means 12, the transmission means 13 transmits the received one packet PKT_N(v) or transmission packet PKT_TR via the antenna 14 by radio communication. to the receiver 2.

FIG. 3 is a schematic diagram of the receiver 2 shown in FIG. Referring to FIG. 3, receiver 2 includes antenna 21 , receiving means 22 , processing means 23 , N buffer 24 and C buffer 25 .

Receiving means 22 receives a packet PKT (packet PKT_N(v) or transmission packet PKT_TR) via antenna 21, and sends the received packet PKT (packet PKT_N(v) or transmission packet PKT_TR) to processing means 23. Output.

When the processing means 23 receives the packet PKT_N(v) from the receiving means 22, the processing means 23 performs N packet reception processing on the packet PKT_N(v) by a method described later. In this case, the processing means 23 stores the packet PKT_N(v) in the N buffer 24 when the packet PKT_N(v) has not been received in the N packet reception process. The processing means 23 then transmits all packets PKT_N(v) stored in the N buffer 24 to the application 30 .

On the other hand, when receiving the transmission packet PKT_TR from the reception means 22, the processing means 23 separates the encoded packet PKT_C and the single packet PKT_N from the encoded packet PKT_C and the single packet PKT_N when the transmission packet PKT_TR includes the encoded packet PKT_C and the single packet PKT_N. Execute the process. Then, the processing means 23 performs the N-packet reception process on the separated single packet PKT_N. In addition, the processing means 23 executes a removal process for removing the information of the single packet PKT_N stored in the N buffer 24 (that is, the received single packet PKT_N) from the encoded packet PKT_C, and performs the encoding after the removal process. When the packet PKT_C' includes a plurality of single packets PKT_N, the encoded packet PKT_C' is stored in the C buffer 25. After that, the processing means 23 executes decoding processing, which will be described later, on the encoded packet PKT_C' stored in the C buffer 25 . In this case, the processing unit 23 performs the N-packet reception process on the single packet PKT_N decoded in the decoding process.

When the transmission packet PKT_TR includes only the encoded packet PKT_C, the processing means 23 sequentially performs the removal processing and the decoding processing described above without performing the separation processing described above.

FIG. 4 is a conceptual diagram showing image transmission. With reference to FIG. 4, features in the case of real-time moving image transmission will be described. An I picture consists of a compressed image that does not use the difference between pictures before and after it, and is large in size. P-pictures are small in size because they carry the difference from the previous picture.

I-pictures and P-pictures are transmitted periodically. The number of packets to be transmitted during periodic transmission is different, and packets may be transmitted at once in bursts. Also, I pictures are generated and transmitted periodically like IPPPIPPPIP.

Bursts occur when transmitting I-pictures, and the size of the bursts is not constant. Packets forming a burst do not arrive all at once, but sequentially.

Furthermore, among the P pictures, P pictures, P pictures, I pictures, P pictures, P pictures, P pictures, I pictures, and P pictures shown in FIG. The time interval between the arrival at the transmitter 1 from the application 20 is T _{interval_1} , and the time interval between the successive arrival of a plurality of packets having I-pictures in their payloads from the application 20 at the transmitter 1 is T, which is shorter than T _{interval_1} . _{interval_2} .

FIG. 5 is a schematic diagram showing the format of a packet. Referring to FIG. 5, packet PKT includes a header and a payload. The header contains the IP address of the destination.

The payload includes Packet Info, region REG1, Coded Info, and region REG2. Region REG1 contains the payload of one packet PKT_N. Region REG2 includes an encoded packet PKT_C that encodes N packets PKT_N(1) to PKT_N(N). _The length of the region REG1 is Lp, and the length of the region _{REG2 is} the maximum value of L1 to Ln. L _p is the data length of one packet PKT_N, and L ₁ to L _n are the data lengths of packets PKT_N(1) to PKT_N(N), respectively.

Packet Info includes identifier N/C, sequence number SN, and data length _Lp . The identifier N/C is an identifier for identifying whether a packet included in the region REG1 is a single packet PKT_N or an encoded packet PKT_C, and consists of "N" or "C". "N" represents a single packet PKT_N, and "C" represents an encoded packet PKT_C. The sequence number SN represents the order of arrival at the transmitter 1 of the packets contained in the region REG1. The data length Lp represents the length of the region _REG1 .

Coded Info includes an identifier N/C, Num coded(N), and Packet Info 1 to Packet Info N. The identifier N/C is an identifier for identifying whether the packet included in the region REG2 is a single packet PKT_N or an encoded packet PKT_C, and consists of "N" or "C". Num coded(N) represents the number of packets PKT_N forming the encoded packet PKT_C included in the region REG2.

Packet Info 1 includes sequence number SN, data length L ₁ , and code C ₁ . Similarly, Packet Info _N includes sequence number SN, data length _LN , and code CN.

In Packet Info 1, the sequence number SN represents the order in which the packet PKT_N(1) constituting the encoded packet PKT_C arrives at the transmitter 1, and the data length L ₁ represents the packet PKT_N(1) constituting the encoded packet PKT_C. ), and the code C1 is the coefficient of the packet PKT_N( ₁ ) when the N packets PKT_N(1) to PKT_N(N) are encoded.

Similarly, in Packet Info N, the sequence number SN represents the order in which the packets PKT_N(N) that make up the encoded packet PKT_C arrive at the transmitter 1, and the data length L _N represents the encoded packet PKT_C. It is the data length of the constituent packet PKT_N(N), and the code CN is the coefficient of the packet PKT_N( _N ) when the N packets PKT_N(1) to PKT_N(N) are encoded.

One packet PKT_N has a structure in which the payload includes Packet Info and region REG1.

Assuming that a packet to be transmitted at once in a burst consists of M _Burst (M _Burst is an integer that satisfies 2≦M _Burst <V) packets PKT_N(1) to PKT_N(M _Burst ), M _Burst (M _Burst −1) packets PKT_N(2) to PKT_N(M _Burst ) other than the packet PKT_N(1) that first arrived at the transmitter 1 among the packets PKT_N(1) to PKT_N(M _Burst ) When each of a (a is an integer equal to or greater than 1) predetermined packets PKT_N(m) selected from arrives at the transmitter 1, Encoding the arrived packets PKT_N(1) to PKT_N(m−1) to generate an encoded packet PKT_C1, and creating a combined packet PKT_N/PKT_C1 by adding the generated encoded packet PKT_C1 to a predetermined packet PKT_N(m) It is generated as a transmission packet PKT_TR.

Therefore, the combined packet PKT_N/PKT_C1 has a payload including [Packet Info/Data of PKT_N/Coded Info/Data of PKT_N(1) to Data of PKT_N(m−1)].

Further, when M _Burst packets PKT_N(1) to PKT_N(M _Burst ) arrive at the transmitter 1 in succession, the encoding that encodes the M _Burst packets PKT_N(1) to PKT_N(M _Burst ) A packet PKT_C2 is generated as a transmission packet PKT_TR.

Therefore, the encoded packet PKT_C2 has a payload including [Coded Info/PKT_N(1) data to PKT_N(M _Burst ) data].

FIG. 6 is a schematic diagram of the buffer 11 shown in FIG. FIG. 6 shows a schematic diagram of the buffer 11 when the size of the buffer 11 is larger than the number M _Burst of packets for burst transmission at one time.

Referring to FIG. 6, buffer 11 is, for example, a ring buffer. Then, the buffer 11 stores M _Burst packets PKT_N(1) to PKT_N(M _Burst ) in ascending order of sequence number SN (that is, in ascending order). Packet PKT_N(M _Burst ) is a packet stored in buffer 11 at the current time, and packet PKT_N(1) to packet PKT_N(M _Burst -1) are packets stored in buffer 11 in the past.

Also, the buffer 11 is configured to overwrite the oldest packets when the number of packets exceeds the maximum number. As a result, the buffer 11 can always store the maximum number of packets.

Sequence number SN ₁ and data length L ₁ of _{packet PKT_N} (1), Sequence number SN ₂ and data length L ₂ of packet _{PKT_N} (2) _{, .}

That is, the packet PKT_N (one of PKT_N(1) to PKT_N(M _Burst )) arriving at the transmitter 1 from the application 20 constitutes the payload, and each area of the buffer 11 stores [SN/L _p /payload/ padding (all "0")] is stored. Note that padding (all "0") is added when the length of [SN/L _p /payload] does not reach the maximum length.

FIG. 7 is a diagram for explaining a method of encoding packets. In FIG. 7, a method of encoding packet X _i (i is 1, 2, 3, . . . ) and encoded packet Y _i−1 will be described.

Referring to FIG. 7, since packet X _i has a data length of L _i bytes, packet X _i has L _i ×8/n components X _i,1 , X _i,2 , X _i,3 , X _{i ,4} , . Each of the components X _{i ,1} , X _i,2 , X _i,3 , X _i,4 , . has a length of The code C _i consists of n-bit long random numbers over the Galois field GF(2 ⁿ ). Here, n consists of 8, for example.

Encoded packet Y _i-1 has components Y _i-1,1 , Y _i-1,2 , Y _i-1,3 , Y i _{- 1,4} , . _/n , Y _{i−1 , Max×8/n} . Components Y _i-1,1 ,Y _i-1,2 ,Y _i-1,3 ,Y _i-1,4 ,...,Y _i-1,Li×8/n ,Y _i-1,Max Each x8 _/n has a length of n bits.

By multiplying each of the components Xi _,1 , Xi _,2 , Xi _,3 , Xi _,4 , . . . , _{Xi , Li×8/n by} the code _Ci , _{, 1} , C _i ·X _i,2 , C _i ·X _{i ,3} , C _i ·X _{i ,4} , . In this case, the multiplication of the code C _i by each of the components X _{i ,1} , X _i,2 , X _i,3 , X _i,4 , . It is implemented as a multiplication over GF(2 ⁿ ).

After that, the exclusive OR of the multiplication result C _i ·X _i,1 and the component Y _i−1,1 is performed to generate the component Y _i,1 , and the multiplication result C _i ·X _i,2 and the component Y _i−1,2 to generate the component Y _i,2 , and the exclusive OR of the multiplication result C _i ·X _i,3 and the component Y _i−1,3 to generate the component Y _i,3 , and the exclusive OR of the multiplication result C _i ·X _i,4 and the component Y _i−1,4 to generate the component Y _i,4 , and so on. and calculating the exclusive OR of the multiplication result C _i · X _{i, Li × 8/n} and the component Y _{i−1, Li × 8/n to generate the component Y i, Li × 8/n} , Further, the exclusive OR of the padding of "0" and the component Yi _{-1,Max.times.8} /n is performed to generate the component Y.sub.i _{,Max.times.8/n} . Thus, the encoded packet _Yi =[Yi _,1 ,Yi _,2 ,Yi _,3 ,Yi _,4 ,..., _Yi,Li*8/n ,...,Yi _{, Max×8/n} ] is generated.

FIG. 8 is a diagram illustrating a method of generating encoded packets when transmitting M _Burst packets PKT_N(1) to PKT_N(M _Burst ).

In FIG. 8, it is determined that the encoded packets are to be transmitted to the receiver 2 at the timing when the packets P ₃ , P ₅ , P ₇ and P ₉ arrive at the transmitter 1 .

Referring to (a) of FIG. 8, M _Burst packets PKT_N(1) to PKT_N(M _Burst ) forming a burst are composed of packets P ₁ to P ₆ . The maximum number of packets that can be stored in the buffer 11 is six. That is, the number M _Burst of packets forming a burst is equal to or less than the size M _Buffer of the buffer 11 .

When the packet P1 arrives at the transmitter ₁ , the processing means 12 of the transmitter ₁ copies the packet P1 to the buffer 11 (see (a) and (i) in FIG. 8). Then, the processing means ₁₂ extracts the packet P1 from the buffer ₁₁ and encodes the extracted packet P1 by the method described in FIG. ₇ to generate the encoded packet C1.

More specifically, the processing means 12 generates an encoded packet Y ₀ ⁼ {000 . Generate _a code C1 consisting of random numbers. Then, the processing means 12 converts the encoded packet Y by the method described in FIG. 7 based _on the packet X ₁ (=P ₁ ), the encoded packet Y ₀ ={000 . ₁ (=C ₁ ) is generated.

Thereafter, when packet P2 arrives at transmitter ₁ , processing means 12 copies packet P2 to buffer 11 (see _FIG . 8(a)(ii)). The processing means ₁₂ then retrieves the packet P2 from the buffer 11 . Then, the processing means 12 generates a code _C2 consisting of n-bit long random numbers on the Galois field GF(2 ⁿ ). Then, the processing means 12 generates the encoded packet Y ₂ (=C ₂ ) based on the packet X ₂ (=P ₂ ), the encoded packet Y ₁ and the code C ₂ by the method explained in FIG. do.

Similarly, encoded packets Y ₃ to Y ₆ (=C ₃ to C ₆ ) are sequentially generated at the timing when the packets P ₃ to P ₆ arrive at the transmitter 1 ((a ) (iii) to (vi)). In this case, when the packet P6 arrives at the transmitter ₁ and is copied to the buffer ₁₁ , the buffer 11 stores the maximum number M _Buffer of packets.

When the packet P3 arrives at the transmitter ₁ , the processing means 12 copies the packet P3 to the buffer 11 (see (a)( _iii ) in FIG. 8) and determines to transmit the encoded packet. Then, the processing means 12 adds the encoded packet Y ₂ (=C ₂ ) generated at the timing when the packet P ₂ arrives at the transmitter 1 to the packet P ₃ to generate a combined packet P ₃ /C ₂ , The generated combined packet P ₃ /C ₂ is output to the transmission means 13 to transmit the combined packet P ₃ /C ₂ to the receiver 2 . It should be noted that transmitting information by combined packet P ₃ /C ₂ is transmission of information by Piggyback.

Further, when the packet P5 arrives at the transmitter ₁ , the processing means 12 copies the packet _P5 to the buffer 11 (see (a) and (v) in FIG. 8) and determines to transmit the encoded packet. Then, the processing means 12 adds the encoded packet Y ₄ (=C ₄ ) generated at the timing when the packet P ₄ arrives at the transmitter 1 to the packet P ₅ to generate the combined packet P ₅ /C ₄ , The generated combined packet P ₅ /C ₄ is output to the transmitting means 13 to transmit the combined packet P ₅ /C ₄ to the receiver 2 .

Then, after the packet P ₆ arrives at the transmitter 1 and the encoded packet Y ₆ (=C ₆ ) is generated, the processing means 12 converts the packets P 1 to P ₁ to which the packet P ₆ constitutes a burst by a method described later. After determining that it is the last packet P ₆ of P ₆ , the untransmitted encoded packet Y ₆ (=C ₆ ) is output to the transmitting means 13 and the encoded packet Y ₆ (=C ₆ ) is independently transmitted. to the receiver 2.

Further, the processing means 12 retrieves the packets P ₁ to P ₆ from the buffer 11 and encodes the retrieved packets P ₁ to P ₆ to generate an encoded packet Y ₇ (=C ₇ ). Then, the processing means 12 outputs the encoded packet Y ₇ (=C ₇ ) to the transmitting means 13 and transmits the encoded packet Y ₇ (=C ₇ ) to the receiver 2 alone.

In this way, when the number of packets M _Burst constituting _a burst is equal to or smaller than the size M _Buffer of the buffer 11, the processing means _{12 generates the encoded packet Y 7 (} =C ₇ ) and transmits it to the receiver 2 .

Referring to FIG. 8(b), M _Burst packets PKT_N(1) to PKT_N(M _Burst ) forming a burst are composed of packets P ₁ to P ₁₀ . The maximum number of packets that can be stored in the buffer 11 is six. That is, the number M _Burst of packets forming a burst is larger than the size M _Buffer of the buffer 11 .

When the packets P ₁ to P ₆ arrive at the transmitter 1, the processing means 12 executes the processing described in (a) of FIG. 8 (see (b) (i) and (ii) of FIG. 8).

Then, when the packet P7 arrives at the transmitter ₁ , the processing means 12 copies the packet _P7 to the buffer 11 (see (b)(iii) in FIG. 8). As a result, the packets P ₁ to P ₆ stored in the buffer 11 when the packet P ₆ arrives at the transmitter 1 are overwritten by the packets P ₂ to P ₇ respectively.

The processing means ₁₂ retrieves the packet P7 from the buffer ₁₁ after copying the packet P7 to the buffer 11 . The processing means ₁₂ then generates a code C7 consisting of n-bit long random numbers on the Galois field GF(2 ⁿ ). Then, the processing means 12 generates encoded packet Y ₇ (=C ₇ ) based on packet X ₇ (=P ₇ ), encoded packet Y ₆ and code C ₇ by the method described in FIG. do.

After that, the processing means 12 similarly generates the encoded packets Y ₈ (=C ₈ ) to Y ₁₀ (=C ₁₀ ) at the timing when the packets P ₈ to P ₁₀ arrive at the transmitter 1. (See (b)(iv) to (vi) in FIG. 8).

After packet P ₁₀ is copied to buffer 11, buffer 11 stores packets P ₅ to P ₁₀ .

After the packet P ₁₀ arrives at the transmitter 1 and the encoded packet Y ₁₀ (=C ₁₀ ) is generated, the processing means 12 converts the packet P ₁₀ into packets P ₁ to P ₁₀ , which constitute a burst, by a method described later. After _determining that it is the _{last packet P10 among} Send to machine 2.

Further, the processing means 12 retrieves the packets P ₅ to P ₁₀ from the buffer 11 and encodes the retrieved packets P ₅ to P ₁₀ to generate an encoded packet Y ₁₁ (=C ₁₁ ). Then, the processing means 12 outputs the encoded packet Y ₁₁ (=C ₁₁ ) to the transmission means 13 and transmits the encoded packet Y ₁₁ (=C ₁₁ ) to the receiver 2 alone.

Thus, when the number M _Burst of packets forming a burst is larger than the size M _Buffer of the buffer 11, the processing means 12 selects the packets P ₅ to P ₁₀ out of the packets P ₁ to P ₁₀ forming the burst. An encoded packet Y ₁₁ (=C ₁₁ ) is generated and transmitted to the receiver 2 .

As described with reference to FIG. 8, coded packets that are transmitted singly include packets that differ depending on the magnitude relationship between the number M _Burst of packets forming a burst and the size M _Buffer of the buffer 11 .

Note that the processing means 12 determines whether or not the last packet PKT_N (M _Burst ) of the M _Burst packets PKT_N(1) to PKT_N(M _Burst ) constituting the burst has arrived at the buffer 11 by the following method. Determined by

M _Burst packets PKT_N(1) to PKT_N(M _Burst ) arrive at the buffer 11 in succession. The elapsed time T _STANDARD , which is the standard elapsed time from the arrival of the packet PKT_N(m) in the buffer 11 to the arrival of one packet PKT_N(m+1) in the buffer 11, is determined in advance as a fixed value, and the determined A fixed elapsed time T _STANDARD is set in the processing means 12 .

The processing means 12 determines that the elapsed time t _ELP from the arrival of one packet PKT_N(m′) out of the M _Burst packets PKT_N(1) to PKT_N(M _Burst ) is longer than the elapsed time t _STANDARD . When the packet PKT_N does not arrive at the buffer 11 even after this, it is determined that the packet PKT_N(m') is the last packet PKT_N(M _Burst ) among the M _Burst packets PKT_N(1) to PKT_N(M _Burst ). Then, it is determined that the last packet PKT_N (M _Burst ) of the M _Burst packets PKT_N(1) to PKT_N(M _Burst ) has arrived at the buffer 11 .

Further, the application 20 sets a flag FG indicating that it is the last packet to the last packet PKT_N (M _Burst ) of the M _Burst packets PKT_N(1) to PKT_N(M _Burst ), and performs the process. Every time the means 12 receives a packet PKT_N from the application 20, it determines whether the flag FG is set in the packet PKT_N, and when it is determined that the flag FG is set in the packet PKT_N, the flag FG is set. It may be determined that the packet PKT_N present is the last packet PKT_N (M _Burst ).

FIG. 9 is a diagram for explaining a method of transmitting packets forming a burst. In FIG. ₉ , when M _Burst packets PKT_N( ₁ ) to PKT_N(M _Burst ) forming a burst are packets P1 to P6, M _Burst packets PKT_N(1) to PKT_N(1) to PKT_N(M Burst) forming a burst A method for transmitting PKT_N(M _Burst ) will be described. In this case, the processing means 12, for example, determines to transmit the encoded packet at the timing when _{one of the packets P3 and P5 arrives at the transmitter 1 , and} the packets P1 _, P2, _P4 and _P6 Assume that it is determined not to transmit the encoded packet at the timing when one of them arrives at the transmitter 1 . It is also assumed that packets P ₁ and P ₃ could not be transmitted to their destinations.

Referring to FIG. 9, packets P ₁ to P ₆ constitute packets transmitted in bursts at one time.

When the packet P1 arrives at the transmitter ₁ , the processing means ₁₂ starts measuring the elapsed time t _{ELP_1} with a timer, copies the packet P1 to the buffer _{11 ,} and copies the packet P1 to the buffer ₁₁ . (that is, packet PKT_N( ₁ ) with m=1), it is determined not to transmit the encoded packet. The processing means 12 then outputs the original packet P1 to the transmitting means ₁₃ and transmits the packet P1 to the receiver ₂ . Thereafter, the processing means ₁₂ retrieves the packet P1 from the buffer ₁₁ and encodes the retrieved packet P1 by the method described above to generate the encoded packet _C1 . _Encoded packet C1 is represented by the following equation.

Subsequently, when the packet P2 arrives at the transmitter ₁ , the processing means 12 _{finishes measuring the elapsed time t ELP_1 and} starts measuring the elapsed time t _{ELP_2} after the arrival of the packet P2. Then, the processing means ₁₂ copies the packet P2 to the buffer ₁₁ , and since the packet P2 is a packet other than the packets P3 and P5 ₍ that is, the packet PKT_N( ₂ ) where m= ₂ ). ), it is determined not to transmit the encoded packet. The processing means ₁₂ then outputs the original packet P2 to the transmitting means 13 and transmits the packet P2 to the receiver ₂ . After that, the processing means 12 retrieves the packets P ₁ and P ₂ from the buffer 11 and encodes the retrieved packets P ₁ and P ₂ by the method described above to generate the encoded packet C ₂ . Encoded packet _C2 is represented by the following equation.

Subsequently, when the packet _P3 arrives at the transmitter 1, the processing means 12 finishes measuring the elapsed time t _{ELP_2} and starts measuring the elapsed time t _{ELP_3} after the arrival of the packet _P3 . Then, the processing means 12 copies the packet P3 to the buffer _{11 ,} and since the packet P3 is a packet corresponding to either of the packets P3 and P5 ₍ that is, the packet _P3 is a packet with m= ₃ Since it is PKT_N(3)), it is determined to transmit the encoded packet. Then, the processing means ₁₂ adds the encoded packet _C2 generated at the timing when the packet P2 arrives at the transmitter ₁ to the original packet P3 to generate the combined packet P3/ _{C2 ,} and the generated Combined packet P ₃ /C ₂ is output to transmitting means 13 to transmit combined packet P ₃ /C ₂ to receiver 2 . After that, the processing means 12 retrieves the packets P ₁ to P ₃ from the buffer 11 and encodes the retrieved packets P ₁ to P ₃ by the method described above to generate the encoded packet C ₃ . _Encoded packet C3 is represented by the following equation.

Subsequently, when the packet _P4 arrives at the transmitter 1, the processing means 12 finishes measuring the elapsed time t _{ELP_3} and starts measuring the elapsed time t _{ELP_4} after the arrival of the packet _P4 . Then, the processing means 12 copies the packet P4 to the buffer 11, and since the packet P4 is a packet other than the packets P3 and P5 ₍ that is, the packet _{PKT_N ( 4} ) where m= ₄ ). ), it is determined not to transmit the encoded packet. Then, the processing means 12 outputs the original packet _P4 to the transmitting means 13 and transmits the packet P4 to the receiver ₂ . Then, the processing means 12 retrieves the packets P ₁ to P ₄ from the buffer 11 and encodes the retrieved packets P ₁ to P ₄ by the method described above to generate the encoded packet C ₄ . Encoded packet _C4 is represented by the following equation.

After that, when packet _P5 arrives at the transmitter 1, the processing means 12 finishes measuring the elapsed time t _{ELP_4} and starts measuring the elapsed time t _{ELP_5} after the arrival of the packet _P5 . Then, the processing means 12 copies the packet P5 to the buffer ₁₁ , and since the packet P5 is a packet corresponding to either of the packets P3 and P5 ₍ that is _, the packet _P5 is a packet with m= ₅ Since it is PKT_N(5)), it is determined to transmit the encoded packet. Then, the processing means 12 adds the encoded packet C ₄ generated at the timing when the packet P ₄ arrives at the transmitter 1 to the original packet P ₅ to generate the combined packet P ₅ /C ₄ . Combined packet P ₅ /C ₄ is output to transmitting means 13 to transmit combined packet P ₅ /C ₄ to receiver 2 . After that, the processing means 12 retrieves the packets P ₁ to P ₅ from the buffer 11 and encodes the retrieved packets P ₁ to P ₅ by the method described above to generate the encoded packet C ₅ . Encoded packet _C5 is represented by the following equation.

Subsequently, when the packet _P6 arrives at the transmitter 1, the processing means 12 finishes measuring the elapsed time t _{ELP_5} and starts measuring the elapsed time t _{ELP_6} after the arrival of the packet _P6 . Then, the processing means 12 copies the packet P6 to the buffer 11, and since the packet _P6 is a packet other than the packets P3 and P5 (that is, the packet _{PKT_N ( 6} ) where m= ₆ ). ), it is determined not to transmit the encoded packet. Then, the processing means 12 outputs the original packet P ₆ to the transmitting means 13 and transmits the packet P ₆ to the receiver 2 . After that, the processing means 12 retrieves the packets P ₁ to P ₆ from the buffer 11 and encodes the retrieved packets P ₁ to P ₆ by the method described above to generate the encoded packet C ₆ . Encoded packet C ₆ is represented by the following equation.

The reason why the encoded packet C6 is _added to the packet P6 and not transmitted to the receiver ₂ is that the timing at which the encoded packet is added to the single packet and transmitted to the receiver ₂ is either packet P3 or _P5 . This is because the timing at which the packet P6 arrives at the buffer ₁₁ is not the timing at which the coded packet is attached to the single packet and transmitted to the receiver 2.

Then, the processing means 12 confirms that no packets arrive at the transmitter 1 even if the elapsed time t _{ELP_6} is longer than the elapsed time T _STANDARD , and the packet P ₆ is the last packet among the packets P ₁ to P ₆ . It is determined to be packet _P6 .

The processing means 12 then determine whether T milliseconds have elapsed since the last packet P ₆ arrived in the buffer 11 . Here, T is the time that satisfies T< _{T_interval_1} , for example, 5 milliseconds.

When the processing means ₁₂ determines that T milliseconds have elapsed since the last packet P6 arrived at the buffer 11, the processing means ₁₂ outputs the encoded packet C6 to the transmission means ₁₃ and transmits the encoded packet C6 to the receiver. 2.

Then, the processing means 12 determines whether or not the number of transmitted encoded packets is K. K is 3, for example. Also, K may be changed according to the number of packets stored in the buffer 11 . In this case, K is determined by K=A+B/M. M is the number of packets stored in the buffer 11, and A and B are constants. And each of A, B, and M is an integer. According to K=A+B/M, as the number of packets M stored in the buffer 11 increases, K decreases, and as the number of packets M stored in the buffer 11 decreases, K increases. Therefore, by determining the transmission number K of the encoded packets by K=A+B/M, when the number M of packets stored in the buffer 11 is the first number, the transmission number K of the encoded packets is set to the first number. is set to the number of transmissions, and when the number of packets M stored in the buffer 11 is a second number larger than the first number, the number of transmissions K of encoded packets is set to a second number smaller than the first number of transmissions. Set to number of transmissions. In other words, the smaller the number M of packets stored in the buffer 11, the more encoded packets are transmitted.

When the processing means 12 determines that the number of transmitted encoded packets is not K, the processing means 12 extracts the packets P ₁ to P ₆ stored in the buffer 11 and encodes the extracted packets P ₁ to P ₆ by the method described above. to generate encoded packet _C7 . Encoded packet C ₇ is represented by the following equation.

Then, the processing means 12 outputs the encoded packet C ₇ to the transmission means 13 and transmits the encoded packet C ₇ to the receiver 2 .

After that, the processing means 12 determines that the number of transmitted encoded packets is not K (=3). Then, the processing means 12 retrieves the packets P ₁ to P ₆ stored in the buffer 11 and encodes the retrieved packets P ₁ to P ₆ by the above-described method to generate the encoded packet C ₈ . Encoded packet C ₈ is represented by the following equation.

In this way, the processing means 12 uses all the packets P ₁ to P ₆ stored in the buffer 11 to generate the encoded packets C ₆ to C ₈ when transmitting the encoded packets alone.

Subsequently, the processing means 12 determines that the number of transmitted encoded packets is K (=3), and clears the buffer 11 .

As shown in equations (6)-(8), encoded packets C ₆ , C ₇ , and C ₈ are encoded packets that include the same packets P ₁ -P ₆ and differ only in coefficient C _i . Since the coefficients C _i consist of n-bit long random numbers on the Galois field GF(2 ⁿ ), for example, the coefficients a ₆₂ and a ₆₄ in equation (6) may be zero. In this case, encoded packet C ₆ will substantially include packets P ₁ , P ₃ , P ₅ and P ₆ . The _same applies to encoded packets C7 and _C8 .

Receiver 2 fails to receive packet P ₁ transmitted from transmitter 1 and receives packet P ₂ transmitted from transmitter 1 . Also, receiver 2 fails to receive combined packet P ₃ /C ₂ transmitted from transmitter 1, and receives packet P ₄ , combined packet P ₅ /C ₄ , packet P ₆ and packet P 6 transmitted from transmitter 1. Encoded packets C ₆ , C ₇ and C ₈ are received sequentially.

Since the receiver 2 failed to receive the packets P ₁ , P ₃ and the encoded packet C ₁ , to decode the failed packets P ₁ , P ₃ from the encoded packets C ₄ , C ₆ , the code information of the received packets P ₂ and P ₄ is removed from the modified packets C ₄ and C ₆ .

More specifically, the receiver 2 removes the information of the received packets P ₂ and P ₄ from the encoded packet C ₄ by the following equation.

Also, the receiver 2 removes the information of the received packets P ₂ , P ₄ , P ₅ and P ₆ from the encoded packet C ₆ according to the following equation.

As a result, the received packets P ₂ , P ₄ and P ₅ from the encoded packet C ₄ ′ and the encoded packet C ₆ after removing the information of the received packets P ₂ and P ₄ from the encoded packet C _{4 ,} P ₆ together contain packets P ₁ and P ₃ .

Then, the left _side of equation (9) computes the exclusive OR of the encoded packet _C4 and the packet P2, and computes the exclusive OR of the result of the exclusive OR operation and the packet _P4 . obtained by Also, the left _side of equation ( ₁₀ ) computes the exclusive OR of the encoded packet C6 and the packet P2, and computes the exclusive OR of the result of the exclusive OR operation and the packet _P4 . , and the exclusive OR of the result of the exclusive OR operation with the packet _P5 , and the exclusive OR operation of the result of the exclusive OR operation with the packet _P6 . Therefore, the receiver 2 can acquire the values of the left sides of equations (9) and (10).

Also, the codes a ₄₁ and a ₄₃ in Equation (9) are included in “Coded Info” of encoded packet C ₄ , and the codes a ₆₁ and a ₆₃ in Equation (10) are included in “Coded Info” of encoded packet C ₆ . It is known because it is included in the Coded Info (see FIG. 5).

Therefore, receiver 2 can decode packets P ₁ and P ₃ that could not be received by solving the simultaneous equations of equations (9) and (10).

Similarly, receiver 2 can decode packets P ₁ and P ₃ that could not be received based on two coded packets arbitrarily selected from coded packets C ₆ to C ₈ .

In this way, when the packets that the receiver 2 could not receive are two packets P ₁ and P ₃ , the transmitter 1 receives more than the number of packets (=2) that the receiver 2 could not receive. By transmitting the encoded packets, the two packets P ₁ and P ₃ that could not be received can be decoded.

In the case where the receiver 2 fails to receive the combined packet P ₅ /C ₂ instead of the combined packet P ₃ /C ₂ , it will be explained that the two packets that could not be received can be decoded by the above method. In this case, receiver 2 has failed to receive two packets P ₁ and P ₅ .

Therefore, the receiver 2 generates the encoded packet C ₂ ′ after removing the information of the received packet P ₂ from the encoded packet C ₂ and the received packets P ₂ , P ₃ , P 3 from the encoded packet C ₆ . An encoded packet C ₆ ″ after removing the information of P ₄ and P ₆ is calculated by the following equation.

Therefore, the receiver 2 can decode the two packets P ₁ and P ₅ that could not be received by solving the simultaneous equations (11A) and (11B).

Even if the packets P ₁ , P ₂ and P ₄ other than the packets P ₃ and P ₅ to which the encoded packets C ₂ and C ₄ are added, respectively, cannot be transmitted to the receiver 2, the receiver 2 cannot transmit the three codes can receive the formatted packets C ₆ , C ₇ and C ₈ .

Therefore, the receiver 2 extracts the encoded packet C ₆ ⁽³⁾ after removing the information of the received packets P ₃ and P ₅ from the encoded packet C ₆ and the received packet P from the encoded packet C ₇ . ₃ and P5 are removed from the encoded packet C7 _{( 3} ⁾ , and the encoded packet _{C8 ( 3} ⁾ after the information of the received packets P3 and P5 is removed from the encoded packet _C8 . ⁾ and As a result, the following equation is obtained.

Receiver 2 can decode packets P ₁ , P ₂ , P ₄ by solving the system of equations (12A), (12B), (12C).

Note that when the encoded packet C after removing the information of the received packet from the encoded packet contains only one packet, the receiver 2 divides the encoded packet C into one packet PKT_N by the following equation. Convert.

In this case, the receiver 2 substitutes the encoded packet C from which the received packet information has been removed for “Y” in equation (13), and either of the encoded packets C from which the received packet information has been removed One code C included in is substituted for "C" in equation (13). Note that the operation of Equation (13) is an operation on the Galois field GF(2 ⁿ ).

FIG. 10 is a diagram for explaining another method of transmitting packets forming a burst. Referring to FIG. 10, processing means 12 generates encoded packets C ₁ -C ₆ each time packets P ₁ -P ₆ are copied to buffer 11, respectively, as explained in FIG.

the processing means ₁₂ , when the packet P2 arrives at the transmitter ₁ , copies the packet P2 to the buffer ₁₁ and appends the encoded packet C1 to the packet P2 to generate _a combined packet _{P2 /} C1; The generated combined packet P ₂ /C ₁ is output to the transmission means 13 to transmit the combined packet P ₂ /C ₁ to the receiver 2 .

Thereafter, the processing means 12 generates the encoded packet _C2 , and when the packet P3 arrives at the transmitter ₁ , copies the packet _P3 to the buffer 11, attaches the encoded packet _C2 to the packet P3 _, and A combined packet P ₃ /C ₂ is generated, and the generated combined packet P ₃ /C ₂ is output to the transmitting means 13 to transmit the combined packet P ₃ /C ₂ to the receiver 2 .

Further, the processing means 12 generates an encoded packet C3 _, and when the packet P4 arrives at the transmitter ₁ , copies the packet _P4 to the buffer ₁₁ , attaches the encoded packet C3 to the packet P4 _, and A combined packet P ₄ /C ₃ is generated, and the generated combined packet P ₄ /C ₃ is output to the transmitting means 13 to transmit the combined packet P ₄ /C ₃ to the receiver 2 .

Further, the processing means 12 generates an encoded packet _C4 , and when the packet P5 arrives at the transmitter ₁ , copies the packet _P5 to the buffer ₁₁ , attaches the encoded packet _C4 to the packet P5, and A combined packet P ₅ /C ₄ is generated, and the generated combined packet P ₅ /C ₄ is output to the transmitting means 13 to transmit the combined packet P ₅ /C ₄ to the receiver 2 .

Further, the processing means ₁₂ generates an encoded packet C5, and when the packet P6 arrives at the transmitter ₁ , copies the packet _P6 to the buffer ₁₁ , attaches the encoded packet C5 to the packet _P6 , and A combined packet P ₆ /C ₅ is generated, and the generated combined packet P ₆ /C ₅ is output to the transmitting means 13 to transmit the combined packet P ₆ /C ₅ to the receiver 2 . Although encoded packet C ₅ includes packets P ₁ to P ₅ (see equation (5)), packet P ₆ which arrived at transmitter 1 last among packets P ₁ to P ₆ forming a burst , the encoded packet C includes all the packets P ₁ to P ₆ stored in the buffer 11 . Therefore, the encoded packet C ₅ in the combined packet P ₆ /C ₅ contains all of the packets P ₁ to P ₆ as shown in FIG. 10 instead of Equation (5) above.

In this way, transmission of encoded packets by Piggyback may be performed in each of the packets P ₂ to P ₆ among the packets P ₁ to P ₆ forming the burst.

After transmitting the combined packet P ₆ /C ₅ to the receiver 2, the processing means 12 transmits the coded packets C ₆ to C ₈ individually to the receiver 2, as explained in FIG.

FIG. 11 is a diagram for explaining still another transmission method of packets forming a burst.

Referring to FIG. 11, processing means 12 generates encoded packets C ₁ to C ₆ each time packets P ₁ to P ₆ are copied to buffer 11, respectively, as explained in FIG.

At the timing when the packets P ₂ to P ₅ respectively arrive at the transmitter 1, the processing means 12 does not attach the encoded packets C ₁ to C ₄ to the packets P ₂ to P ₅ , respectively, and adds the packets P 2 to P 5 to the packets P ₂ to P ₅ respectively. to the receiver 2 independently.

Then, when packet P6 arrives at transmitter ₁ , processing means ₁₂ adds encoded packet C5 to packet _P6 to generate combined packet _P6 /C5, and generates combined packet _P6 / _C5 . C ₅ is output to the transmitting means 13 to transmit the combined packet P ₆ /C ₅ to the receiver 2 . Again, encoded packet P ₅ contains all of packets P ₁ -P ₆ as shown in FIG. 11, rather than equation (5) above.

In this way, transmission of encoded packets by Piggyback may be performed only in the last packet P ₆ of the packets P ₁ to P ₆ forming the burst.

After transmitting the combined packet P ₆ /C ₅ to the receiver 2, the processing means 12 transmits the coded packets C ₆ to C ₈ individually to the receiver 2, as explained in FIG.

As described with reference to FIGS. 9 to 11, in the embodiment of the present invention, transmission of encoded packets by combined packets (that is, transmission of encoded packets by Piggyback) consists of packets P ₁ to P composing a burst. ₆ , it may be executed at the timing when one or more packets selected from packets P ₂ to P ₆ each arrive at the transmitter 1 .

FIG. 12 is a flow chart for explaining the operation of transmitter 1 shown in FIGS.

Referring to FIG. 12, when transmitter 1 starts operating, processing means 12 sets sequence number SN to SN=0 (step S1). Then, the processing means 12 determines whether or not the packet has arrived at the buffer 11 (step S2).

When it is determined in step S2 that packet PKT_N has arrived at buffer 11, processing means 12 sets SN=SN+1 (step S3), adds sequence number SN and packet length L to packet PKT_N, The number SN, packet length L and packet PKT_N are copied to the buffer 11 (step S4). By executing step S3, the sequence number SN indicating the order of arrival at the buffer 11 (that is, the transmitter 1) is stored in the buffer 11 together with the packet PKT_N and the packet length L. FIG.

After that, the processing means 12 determines whether or not to transmit the encoded packet C (step S5). As described with reference to FIGS. 9 to 12, transmission of encoded packets by combined packets (that is, transmission of encoded packets by Piggyback) is performed by transmitting packets P ₂ to P out of packets P ₁ to P ₆ forming a burst. ₆ are executed at the timing when one or more packets selected from 6 respectively arrive at the transmitter 1, so the packet P _Piggyback that executes the transmission of the encoded packet by the combined packet (that is, the transmission of the encoded packet by Piggyback) is determined in advance, and when the determined packet P _{Piggyback arrives} at the buffer 11 (that is, the transmitter 1), the processing means 12 determines to transmit the encoded packet C, and packets other than the packet P _Piggyback are stored in the buffer 11 (ie, transmitter 1), it decides not to transmit encoded packet C.

When it is determined in step S5 that the encoded packet C is to be transmitted, the encoded packet is attached to the N packet PKT_N (step S6) to generate a combined packet.

Then, in step S5, when it is determined not to transmit the encoded packet C, or after step S6, the processing means 12 outputs the packet to the transmission means 13, and the transmission means 13 receives the packet from the processing means 12. is transmitted to the receiver 2 via the antenna 14 (step S7).

After that, the processing means 12 generates an encoded packet C from the packets stored in the buffer 11 by the method described above (step S8).

Then, the series of operations moves to step S2.

On the other hand, when it is determined in step S2 that no packet has arrived at the buffer 11, the processing means 12 determines whether T milliseconds have passed since the last packet arrived at the buffer 11 (step S9).

In step S9, when it is determined that T milliseconds have passed since the last packet arrived at the buffer 11, the processing means 12 outputs the encoded packet C to the transmission means 13, and the transmission means 13 processes The encoded packet C received from means 12 is transmitted to receiver 2 via antenna 14 (step S10).

After that, the processing means 12 determines whether or not the number of transmissions of the encoded packet C is K (step S11).

When it is determined in step S11 that the number of transmitted encoded packets C is not K, the processing means 12 generates encoded packets C from the packets stored in the buffer 11 (step S12). After that, the series of operations proceeds to step S10, and steps S10 to S12 are repeatedly executed until it is determined that the number of transmitted encoded packets C is K in step S11.

Then, when it is determined in step S11 that the number of transmitted encoded packets C is K, the processing means 12 clears the buffer 11 (step S13). After that, the series of operations moves to step S2. Further, when it is determined in step S9 that T milliseconds have not elapsed since the last packet arrived at the buffer 11, the series of operations proceeds to step S2.

FIG. 13 is a flow chart for explaining the detailed operation of step S8 shown in FIG.

Referring to FIG. 13, after step S7 in FIG. 12, processing means 12 sets i=1 (step S81). Here, i is an argument indicating the sequence number SN of each packet stored in the buffer 11 when step S8 in FIG. 12 is executed. i=1 represents the oldest packet among the packets stored in the buffer 11 .

After step S81, the processing means 12 generates an encoded packet Y ₀ ={000...0} consisting of "000...0" having a length of n bits (step S82).

Then, the processing means 12 acquires the packet _Xi from the buffer 11 (step S83).

After that, the processing means 12 generates an n-bit random number using the Galois field (GF(2 ⁿ )), and stores the generated n-bit random number in C _i (step S84).

Then, the processing means 12 multiplies each element X _i,1 to X _i,Li×8/n of the packet X _i by C _i and calculates the exclusive OR of C _i ·X _i and Y _i−1 do. That is, the processing means 12 calculates _Yi by the following equation (step S85).

Subsequently, the processing means 12 adds the sequence number SN _i , packet length L _i and code C _i of the packet X _i to the coded info (step S86).

Then, the processing means 12 determines whether or not i=I (step S87). Here, I indicates the maximum value of sequence numbers SN of packets stored in the buffer 11 at the time when step S8 in FIG. 12 is executed.

When it is determined in step S87 that i is not equal to I, the processing means 12 sets i=i+1 (step S88). Thereafter, the series of operations proceeds to step S83, and steps S83 to S88 are repeatedly executed until it is determined that i=I in step S87.

Then, when it is determined that _i =I in step S87, the processing means 12 generates a coded packet consisting of Yi and coded info (step S89).

After that, the series of operations moves to step S2 in FIG.

The detailed operation of step S12 in FIG. 12 is also executed according to the flowchart shown in FIG. In this case, when it is determined in step S11 of FIG. 12 that the number of transmissions of the encoded packets is not K, steps S81 to S89 are sequentially executed. to

The transmitter 1 repeatedly executes steps S1 to S13 shown in FIG. 12 (including the flowchart shown in FIG. 13) as long as it is driven.

In the flowchart shown in FIG. 12 (including the flowchart shown in FIG. 13), after step S1 is executed, the processing means 12, in step S2, processes packets PKT_N(1) (P picture shown in FIG. 4) that do not constitute a burst. ) has arrived at the buffer 11, the above-described steps S3 and S4 are sequentially executed, and then in step S5 it is determined not to transmit the encoded packet C, and in step S7 packet PKT_N(1) is transferred to It transmits to the receiver 2 via the transmitting means 13 and the antenna 14 .

After that, the processing means 12 generates an encoded packet C in step S8, and after step S8, the series of operations proceeds to step S2.

Each time the processing means 12 determines in step S2 that a packet PKT_N that does not constitute a burst (a packet indicating a P picture shown in FIG. 4) has arrived in the buffer 11, "NO ” and step S7 are sequentially executed to transmit a single packet PKT_N to the receiver 2, and an encoded packet C is generated in step S8. After that, the series of operations moves to step S2.

In step S8, the packet PKT_N(1) that does not constitute a burst is encoded to generate an encoded packet. In step S2, it is determined that the packet has not arrived. If it is determined that T milliseconds have passed since the arrival, the coded packet (consisting of approximately N packets) will be transmitted K times (see steps S10 to S12).

Next, the operation of the transmitter 1 when a packet forming a burst (for example, one of the packets P ₁ to P ₆ shown in FIG. 9) arrives at the buffer 11 will be described.

The processing means 12 determines in step S2 that the packet P1 has arrived in the buffer ₁₁ , and after sequentially executing the steps S3 and S4 described above, determines in step S5 not to transmit the encoded packet C, and in step S7. , the packet P ₁ is transmitted to the receiver 2 via the transmitting means 13 and the antenna 14 .

Then, in step S8, the processing means ₁₂ generates _an encoded packet C1 including the packet P1, after which the series of operations proceeds to step S2.

Thereafter, the processing means 12 determines in step S2 that the packet P2 has arrived in the buffer ₁₁ , and after sequentially executing the above-described steps S3 and S4, determines in step S5 not to transmit the encoded packet C, At step S7, the packet P2 is transmitted to the receiver ₂ via the transmitting means 13 and the antenna . Then, at step S8, the processing means ₁₂ generates _an encoded packet _C2 including the packets P1 and P2. After that, the series of operations moves to step S2.

Subsequently, in step S2, the processing means 12 determines that the packet P3 has arrived in the buffer 11, and after sequentially executing the above _- described steps S3 and S4, in step S5, the encoded packet C (=encoded packet C ₁ ) is to be transmitted, and in step S6 _, the encoded packet _C2 is added to the packet P3 to generate a combined packet _P3 / _C2 . The processing means 12 then transmits the combined packet P ₃ /C ₂ to the receiver 2 via the transmitting means 13 and the antenna 14 in step S7. After that, the processing means 12 generates an encoded packet C ₃ containing the packets P ₁ to P ₃ in step S8. Then, the series of operations moves to step S2.

After generating the encoded packet C3 _, the processing means 12 determines in step S2 that the packet P4 has arrived in the buffer 11, and after sequentially executing the above _- described steps S3 and S4, in step S5 C is determined not to be transmitted, and packet P4 is transmitted to receiver ₂ via transmission means 13 and antenna 14 in step S7. Then, in step S8, the processing means 12 generates an encoded packet C ₄ containing the packets P ₁ to P ₄ . After that, the series of operations moves to step S2.

After generating the encoded packet _C4 , the processing means 12 determines in step S2 that the packet P5 has arrived in the buffer 11, and after sequentially executing the above _- described steps S3 and S4, in step S5 C is determined to be transmitted, and in step S6, encoded packet _C4 is added to packet _P5 to generate combined packet _P5 / _C4 . The processing means 12 then transmits the combined packet P ₅ /C ₄ to the receiver 2 via the transmitting means 13 and the antenna 14 in step S7.

Thereafter, the processing means 12 generates an encoded packet C ₅ containing packets P ₁ to P ₅ in step S8. Then, the series of operations moves to step S2.

After generating the encoded packet C5, the processing means ₁₂ determines in step S2 that the packet P6 has arrived in the buffer ₁₁ , and after sequentially executing steps S3 and S4 described above, in step S5 C is determined not to be transmitted, and packet P6 is transmitted to receiver ₂ via transmission means 13 and antenna 14 in step S7. Then, in step S8, the processing means 12 generates an encoded packet C ₆ containing the packets P ₁ to P ₆ . After that, the series of operations moves to step S2.

Subsequently, the processing means 12 determines in step S2 that no packet has arrived in the buffer ₁₁ , and in step S9 T milliseconds have passed since the last packet (=packet P6) arrived in the buffer 11. Then, in step S10, the encoded packet C6 is transmitted to the receiver ₂ via the transmitting means 13 and the antenna 14. FIG. Then, in step S11, the processing means 12 determines that the number of transmitted encoded packets C is not K (=3), and in step S12, the packets P ₁ to P 6 stored in the buffer 11 are converted to packets P ₁ to P ₆ . Generate encoded packet _C7 containing _P6 .

The processing means 12 then transmit the encoded packet C7 to the receiver ₂ via the transmitting means 13 and the antenna 14 in step S10.

Subsequently, in step S11, the processing means ₁₂ determines that the number of transmitted encoded packets _C is not K (= ₃ ). ~ P ₆ to generate an encoded packet C ₈ .

The processing means 12 then transmit the encoded packet C ₈ to the receiver 2 via the transmitting means 13 and the antenna 14 in step S10.

Then, the processing means 12 determines that the number of transmitted encoded packets C is K (=3) in step S11, and clears the buffer 11 in step S13.

In the flowchart shown in FIG. 12, the number of encoded packets transmitted in step S11 is the number of encoded packets transmitted in step S10, and includes the number of encoded packets transmitted in step S7 as combined packets. do not have.

Also, as described in (a) of FIG. 8, when the number M _Burst of packets forming a burst is equal to or smaller than the size M _Buffer of the buffer 11, it is determined in step S2 of FIG. 12 that no packet has arrived. At this time, since the packets P ₁ to P ₆ are stored in the buffer 11, the processing means 12 can generate encoded packets C ₇ and C ₈ containing all of the packets P ₁ to P ₆ in step S12. can. As a result, in step S7, combined packets including encoded packets (at least one of encoded packets C ₁ to C ₅ ) or single packets (packets P ₁ , P ₂ , P ₄ , P ₆ in FIG. 9, etc.) cannot be received by the receiver ₂ , in step _S10 , the number of encoded packets (code By determining “K” to transmit to the receiver 2 the packets C ₇ , C ₈ , etc.) that the receiver 2 could not receive (some of the packets P ₁ to P ₆ ) can be decrypted.

Furthermore, as described in (b) of FIG. 8, when the number M _Burst of packets forming a burst is larger than the size M _Buffer of the buffer 11, packets P ₂ to P ₁₀ are respectively Combined packets P ₂ /C ₁ , P ₃ /C ₂ , P ₄ /C ₃ , P 2 /C 1 , P 3 /C 2 , P 4 /C 3 , obtained by adding encoded packets C ₁ to C ₉ to packets P ₂ to P ₁₀ at the timing of arrival at the transmitter 1, respectively. When P ₅ /C ₄ , P ₆ /C ₅ , P ₇ /C ₆ , P ₈ /C ₇ , P ₉ /C ₈ and P ₁₀ /C ₉ are transmitted to the receiver 2, the encoded packet C ₁ to C ₉ are represented by the following equations.

In equation (15), the number of packets included in the encoded packets C ₆ to C ₉ is 6 because the maximum number of packets M _Buffer that can be stored in the buffer 11 is " ₆ ". is copied into buffer 11, packets P ₁ -P ₆ are overwritten by packets P ₂ -P ₇ , and when packet P ₈ is copied into buffer 11, packets P ₂ -P ₇ are overwritten by packets P ₃ -P ₈ and packet P ₉ is copied to buffer 11, packets P ₃ -P ₈ are overwritten by packets P ₄ -P ₉ .

A _single packet P1 and combined packets _P2 / _{C1 , P3 / C2 , P4} /C3, _P5 / _C4 , _P6 /C5, _P7 /C6, _P8 /C ₇ , P ₉ /C ₈ , P ₁₀ /C ₉ are transmitted in step S7 of FIG.

_Single packet P1 and combined packets _P2 / _{C1 , P3 / C2 , P4} /C3, _P5 / _C4 , _P6 /C5, _P7 /C6, _P8 / _C7 , If half of the number (= ₁₀ ) of P9/ _C8 , P10/ _C9 could not be received by the receiver ₂ , the _nine combined packets P2/C1 _, P3 _{/ C2} , at least _four combined packets of _P4 /C3, _P5 / _{C4 , P6} /C5, _P7 / _C6 , _P8 / _C7 , _P9 / _C8 and _P10 / _C9 can be received by the receiver 2.

In this case, receiver 2 can receive packet P ₁ and four combined packets P ₂ /C ₁ , P ₃ /C ₂ , P ₄ /C ₃ , P ₅ /C ₄ and five combined packets Assuming that P ₆ /C ₅ , P ₇ /C ₆ , P ₈ /C ₇ , P ₉ /C ₈ and P ₁₀ /C ₉ could not be received, the receiver 2 could not receive packets P ₆ -P ₁₀ . Therefore, packets P ₁ to P ₅ have been received.

However, the transmitter 1 can transmit five encoded packets C ₁₀ to C ₁₄ including the packets P ₅ to P ₁₀ to the receiver 2 by repeating steps S10 to S12 of FIG. 12 five times. The five encoded packets C ₁₀ -C ₁₄ are represented by the following equations.

Then, the receiver 2 selects, for example, four encoded packets C ₁₀ to C ₁₃ from Equation (16), and obtains the information of the received packet P ₅ from the four encoded packets C ₁₀ to C ₁₃ . Remove to generate encoded packets C ₁₀ ', C ₁₁ ', C ₁₂ ', C ₁₃ '. Since each of the encoded packets C ₁₀ ', C ₁₁ ', C ₁₂ ', C ₁₃ ' includes four packets P ₆ -P ₁₀ , packets P ₆ -P ₁₀ can be obtained by solving the following simultaneous equations: can be decrypted.

and receiver ₂ can receive packet P1 and _five combined packets _P6 /C5, _P7 / _C6 , _P8 / _C7 , _P9 / _C8 , _P10 / _C9 , If the four combined packets P ₂ /C ₁ , P ₃ /C ₂ , P ₄ /C ₃ , P ₅ /C ₄ have not been received, packets P ₂ -P ₅ have not been received.

Then, since the number of packets that could not be received is "4", four encoded packets C ₆ to C ₉ are selected from the encoded packets C ₅ to C ₉ of equation (15), and the encoded packets Encoded packets C ₆ ′ to C ₉ obtained by removing the information of the received packets P ₁ and P ₆ to P ₉ from C ₆ to C ₉ and removing the information of the received packets P ₁ and P ₆ to P ₉ The packets P ₂ -P ₅ can be decoded by solving the system of equations showing .

In this way, even when the number M _Burst of packets forming a burst is larger than the size M _Buffer of the buffer 11, the receiver 2 can decode packets that could not be received.

Furthermore, in the flowchart shown in FIG. 12 (including the flowchart shown in FIG. 13), the transmitter 1 generates a single packet each time packets P ₁ to P ₆ constituting a burst arrive at the transmitter 1. Alternatively, since a combined packet (including an encoded packet) is transmitted to the receiver 2, a plurality of packets P ₁ to P ₆ forming a burst can be transmitted to the receiver 2 with low delay.

Transmitter 1 transmits packets forming bursts (all packets P ₁ to P ₆ shown in FIG. 9) to receiver 2, and then packets PKT_N not forming bursts (packets showing P pictures shown in FIG. 4). has arrived at the buffer 11, the packet PKT_N (the packet representing the P-picture shown in FIG. 4) not forming a burst is transmitted to the receiver 2 by the method described above.

Thus, transmitter 1 transmits non-burst packets and burst-forming packets to receiver 2 according to the flowchart shown in FIG. 12 (including the flowchart shown in FIG. 13).

FIG. 14 is a flowchart for explaining the operation of the receiver 2 shown in FIGS. 1 and 3. FIG.

Referring to FIG. 14, when the operation of receiver 2 is started, receiving means 22 receives a packet via antenna 21 (“YES” in step S21), and sends the received packet to processing means 23. Output.

The processing means 23 receives the packet PKT from the receiving means 22, and determines whether or not the received packet PKT is the N packet PKT_N, thereby determining whether or not the N packet PKT_N has been received (step S22). In this case, the processing means 23 determines that N packets PKT_N have been received when the identifier N/C of the packet info of the packet PKT consists of "N" and the packet PKT does not include the coded info and the region REG2. , when the identifier N/C of the packet info of the packet PKT consists of "C", or when the identifier N/C of the packet info of the packet PKT consists of "N" and the identifier N/C of the coded info consists of "C" , it is determined that N packets PKT_N have not been received.

When it is determined in step S22 that the N packet PKT_N has not been received, the processing means 23 determines whether or not the combined packet (packet transmitted by Piggyback) has been received (step S23). In this case, the processing means 23 receives the combined packet when the identifier N/C of the packet info of the packet PKT consists of "N" and the identifier N/C of the coded info of the packet PKT consists of "C". , and when the identifier N/C of the packet info of the packet PKT is "C", it is determined that the combined packet has not been received.

When it is determined in step S23 that the combined packet has been received, the processing means 23 separates the N packet and the C packet (=encoded packet) (step S24).

After that, the processing means 23 determines whether or not there are N packets PKT_N (step S25).

When it is determined in step S25 that there are N packets PKT, or when it is determined in step S22 that N packets PKT_N have been received, processing means 23 executes an N packet reception process (step S26).

After that, the processing means 23 determines whether or not there is a C packet (=encoded packet) (step S27).

Then, when it is determined in step S23 that no combined packet has been received, or when it is determined in step S25 that there is no N packet PKT_N, or in step S27 when there is a C packet (=encoded packet). When determined, the processing means 23 removes the information of the received N-packet PKT_N from the C-packet (=encoded packet) (step S28).

Subsequently, the processing means 23 executes decoding processing (step S29). Then, the processing means 23 determines whether or not the decryption is successful (step S30).

Steps S29 and S30 are repeatedly executed until it is determined in step S30 that decoding has failed when it is determined in step S30 that decoding has failed.

Then, when it is determined in step S27 that there is no C packet (=encoded packet), or when it is determined in step S30 that decoding is not possible, the series of operations proceeds to step S21. Thereafter, the receiver 2 repeats steps 21 to S30 as long as it is driven.

When it is determined in step S23 that the combined packet has not been received, the sequence of operations proceeds to step S28 because the packets received by the receiver 2 are N packet PKT_N, encoded packet PKT_C and There are three types of combined packets, and in step S22 it is determined that N packets PKT_N have not been received, and in step S23 it is determined that no combined packet has been received. , is the encoded packet PKT_C.

FIG. 15 is a flow chart for explaining the detailed operation of step S26 shown in FIG.

15, when it is determined that N packets PKT_N have been received in step S22 of FIG. 14, or when it is determined that there are N packets PKT_N in step S25 of FIG. Whether the sequence number SN _rx of the received N packet PKT_N is less than or equal to the sequence number SN _sent of the N packet PKT_N already received and transmitted to the application 30 (that is, the sequence number of the N packet stored in the N buffer 24) It is determined whether or not the received N packets PKT_N have been stored in the N buffer 24 (step S261).

In step S261, when it is determined that the sequence number SN _rx of the received N-packet PKT_N has been received and is equal to or less than the sequence number SN _sent of the N-packet PKT_N that has been transmitted to the application 30, or the received N-packet PKT_N is When it is determined that it has been stored in the N buffer 24, the processing means 23 discards the received N packets PKT_N (step S262).

On the other hand, in step S261, the sequence number SN _rx of the received N packets PKT_N has been received and is not equal to or less than the sequence number SN _sent of the N packets PKT_N that have been transmitted to the application 30, and the received N packets PKT_N are stored in the N buffers. 24, the processing means 23 stores the received N packets PKT_N(SN _rx ) in the N buffer 24 (step S263).

Then, the processing means 23 sets i=1 (step S264), and determines whether or not the packet PKT_N having the sequence number SN _sent +i exists in the N buffer 24 (step S265). Note that i is an integer of 1, 2, 3, . . .

When it is determined in step S265 that the packet PKT_N with the sequence number SN _sent +i exists in the N buffer 24, the processing means 23 transmits the packet PKT_N with the sequence number SN _sent +i to the application 30 (step S266). Then, the processing means 23 sets i=i+1 (step S267). Thereafter, the series of operations proceeds to step S265, and steps S265 to S267 are repeatedly executed until it is determined in step S265 that the packet PKT_N having the sequence number SN _sent +i does not exist in the N buffer 24.

Then, when it is determined in step S265 that the packet PKT_N having the sequence number SN _sent +i does not exist in the N buffer 24, the processing means 23 sets SN _sent =SN _sent +i-1 (step S268).

After step S262 or step S268, the series of operations proceeds to step S27 in FIG.

Steps S 263 to S 267 shown in FIG. 15 are steps for storing the newly received N packets PKT_N in the N buffer 24 and transmitting them to the application 30 . Then, when i≧2, if it is determined in step S265 that the packet PKT_N having the sequence number SN _sent +i does not exist in the N buffer 24, in step S268, the received N packet PKT_N in the N buffer 24 The latest sequence number _{SN_sent} is updated.

FIG. 16 is a flow chart for explaining the detailed operation of step S28 shown in FIG.

16, when it is determined in step S23 of FIG. 14 that no combined packet has been received, or when it is determined in step S25 of FIG. 14 that there are no N packets, or when step S27 of FIG. , when it is determined that there is a C packet (encoded packet), the processing means 23 sets _i =1 (step S281) and acquires the packet Xi from the N buffer 24 (step S282). Here, i represents each packet X _i stored in the N buffer 24 and ranges from 1 to I. And I is the total number of packets X _i stored in the N buffer 24 .

After step _S282 , the processing means 23 determines whether or not the sequence number SN of the packet Xi is included in the coded info of the encoded packet Y (step S283).

When it is determined in step S283 that the sequence number SN of the packet X _i is included in the coded info of the encoded packet Y, the processing means 23 computes the exclusive OR of the encoded packet Y and the packet X _i . Thus, the information of the received packet _Xi is removed from the encoded packet Y (step S284).

Then, when it is determined in step S283 that the sequence number SN of the packet X _i is not included in the coded info of the encoded packet Y, or after step S284, the processing means 23 determines whether i=I. is determined (step S285).

When it is determined in step S285 that i is not equal to I, processing means 23 sets i=i+1 (step S286). After that, the series of operations proceeds to step S282, and steps S282 to S286 are repeatedly executed until it is determined that i=I in step S285.

Then, when it is determined in step S285 that i=I, the processing means 23 determines whether or not all the information included in the encoded packet Y has been received (step S287). In this case, when the encoded packet Y is Y={000 . When Y is not Y={000 . has not been received).

When it is determined in step S287 that all the information included in the encoded packet Y has not been received, the processing means 23 determines that the number of N packets included in the encoded packet Y is "1". It is determined whether or not there is (step S288).

When it is determined in step S288 that the number of N packets included in encoded packet Y is not "1", processing means 23 stores encoded packet Y in C buffer 25 (step S289).

On the other hand, when it is determined in step S288 that the number of N packets included in the encoded packet Y is "1", the processing means 23 converts the encoded packet Y into the packet X according to equation (13), The above-described "N packet reception process" (flowchart shown in FIG. 15) is executed for the converted packet X (step S290).

Then, when it is determined in step S287 that all of the information contained in the encoded packet Y has been received, or after step S289 or after step S290, the series of operations is the steps in FIG. Move to S29.

In the flowchart shown in FIG. 16, steps _S282 to S286 are repeatedly executed until it is determined that i=I in step S285. _XI information is removed. That is, by repeatedly executing steps S282 to S286 until it is determined that i=I in step S285, a plurality of packets not stored in the N buffer 24 (=a plurality of packets that have not been received) An encoded packet C is generated containing only

FIG. 17 is a flow chart for explaining the detailed operation of step S29 shown in FIG.

Referring to FIG. 17, after step S28 of FIG. 14 or when it is determined in step S30 that decoding is possible, processing means 23 determines whether two or more encoded packets Y exist in C buffer 25. is determined (step S291).

When it is determined in step S291 that two or more encoded packets Y do not exist in the C buffer 25, the series of operations proceeds to step S21 in FIG.

On the other hand, when it is determined in step S291 that two or more encoded packets Y exist in the C buffer 25, the processing means 23 sets i=1 (step S292). Here, i represents each encoded packet Y _i stored in the C buffer 25 and is 1 to I. and I is the total number of encoded packets Y _i stored in the C buffer 25 .

After step S292, the processing means 23 acquires the encoded packet Y _i from the C buffer 25 (step S293).

Then, the processing unit 23 executes "remove the information of the received packet X _i from the encoded packet" (flow chart in FIG. 16) for the encoded packet Y _i (step S294).

Thereafter, the processing means 23 determines whether or not the number of N packets included in the encoded packet Yi is equal to or less than "1" (step _S295 ).

When it is determined in step S295 that the number of N packets included in the encoded packet Y _i is equal to or less than "1", the processing means 23 deletes the encoded packet Y _i from the C buffer 25 (step S296).

Then, when it is determined in step S295 that the number of N packets included in the encoded packet Y _i is not equal to or less than "1", or after step S296, the processing means 23 determines whether i=I. (step S297).

When it is determined in step S297 that i is not equal to I, processing means 23 sets i=i+1 (step S298). Thereafter, the series of operations proceeds to step S293, and steps S293 to S298 are repeatedly executed until it is determined that i=I in step S297.

Then, when it is determined in step S297 that i=I, the processing means 23 determines whether or not a plurality of encoded packets C including a plurality of N packets exist in the C buffer 25 (step S299). .

In step S299, when it is determined that a plurality of encoded packets C including a plurality of N packets exist in the C buffer 25, the processing means 23 acquires a plurality of encoded packets Y from the C buffer 25, C packet (encoded packet) is decoded by solving the simultaneous equations representing the encoded packet Y of (step S300).

Then, when it is determined in step S299 that a plurality of encoded packets C including a plurality of N packets do not exist in the C buffer 25, or after step S300, the processing means 23 sets i=1 (step S301 ), and it is determined whether or not the number of successfully decoded N packets is equal to or greater than "i" (step S302).

In step S302, when it is determined that the number of N packets that can be decoded is equal to or greater than "i", the processing means 23 executes "N packet reception processing" (flowchart in FIG. 15) for the decoded N packets. (step S303). Then, the processing means 23 sets i=i+1 (step S304). Thereafter, the series of operations proceeds to step S302, and steps S302 to S304 are repeatedly executed until it is determined in step S302 that the number of N packets that can be decoded is not equal to or greater than "i".

Then, in step S302, when it is determined that the number of N packets that can be decoded is not equal to or greater than "i", the series of operations proceeds to step S30 in FIG.

In the flowchart shown in FIG. 17, when it is determined in step S287 in FIG. 16 that all the information contained in the encoded packet Y has been received, or after step S290, when the process proceeds to step S291, In step S291, it is determined that two or more encoded packets Y do not exist in the C buffer 25, and the series of operations proceeds to step S21 in FIG.

On the other hand, when the process proceeds to step S291 after step S289 in FIG. 16, when it is determined in step S291 that two or more encoded packets Y exist in the C buffer 25, the steps S292 to S304 described above are sequentially performed. When it is determined in step S291 that two or more encoded packets Y do not exist in the C buffer 25, the series of operations proceeds to step S21 in FIG.

In the flowchart shown in FIG. 17, steps S302 to S304 are repeatedly executed until it is determined in step S302 that the number of N packets that can be decoded is not equal to or greater than i. This is because the "N packet reception process" (flow chart in FIG. 15) is executed for all the N packets obtained by this.

FIG. 18 is a diagram showing transitions of the N buffer 24 and the C buffer 25 when receiving packets forming a burst.

FIG. 18 shows transitions of the N buffer 24 and the C buffer 25 at the time of receiving the packets forming the burst when the packets forming the burst consist of the packets P ₁ to P ₆ shown in FIG.

Referring to FIG. 18, when transmitter ₁ transmits packet P1, receiver ₂ fails to receive packet P1. Therefore, in step S21 of FIG. Packet _P1 is not received. As a result, no packet is stored in the N buffer 24 and the C buffer 25 (see (a) of FIG. 18).

After that, when the transmitter 1 transmits the packet P2, the receiving means 22 of the receiver ₂ receives the packet P2 via the antenna 21 (see "YES" in step S21 of _FIG . 14), and the received packet P2 is _output to the processing means 23 .

_When the processing means 23 receives the packet P2 from the receiving means 22, the processing means 23 confirms that the identifier N/ _C of the Packet info of the packet P2 consists of "N" and determines that N packets have been received (see FIG. 14). See "YES" in step S22). Then, the processing means 23 executes the N-packet reception process for the packet P2 ₍ see step S26 in _FIG . 14), and the sequence number SN _rx of the packet P2 has been received and has been transmitted to the application 30. It is determined that the sequence number SN _sent of the packet PKT_N (that is, the sequence number of the N packets stored in the N buffer 24) is larger than the received packet and that the received packet has not been stored in the N buffer 24 (“ in step S261 of FIG. 15) NO"), the packet P2 is stored in the _N buffer 24 and the packet P2 is transmitted to the application 30 (see steps S263 to S266 in _FIG . 15). Then, when i=2, the processing means 23 determines that the packet of SN _sent +i (=SN _sent +2) does not exist in the N buffer 24 (see "NO" in step S265 of FIG. 15), _Sent = SN _sent +i-1 = SN _sent +2-1 = SN _sent +1 updates the sequence number SN _sent of the N packet PKT_N stored in the N buffer 24 (see step S268 in FIG. 15). After that, the processing means 23 determines that there is no C packet (see "NO" in step S27 of FIG. 14), and the operation of the receiver 2 proceeds to step S21 of FIG. At this stage, packet P2 is stored in N buffer 24 (see _FIG . 18(b)).

Subsequently, when the transmitter 1 transmits the combined packet _P3 / _{C2, the receiver 2 fails} to receive the combined packet _P3 /C2. The means 22 do not receive the combined packet _P3 / _C2 . As a result, the states of N-buffer 24 and C-buffer 25 do not change (see FIG. 18(c)).

After that, when transmitter 1 transmits packet _P4 , receiver ₂ performs the same operation as when receiving packet P2 described above. As a result, packet P4 is stored in N buffer 24 (see ( _d ) in FIG. 18).

Then, when the transmitter 1 transmits the combined packet P ₅ /C ₄ , the receiving means 22 of the receiver 2 receives the combined packet P ₅ /C ₄ via the antenna 21 ("YES" in step S21 of FIG. 14). ”), and outputs the received combined packet P ₅ /C ₄ to the processing means 23 .

When the processing means 23 receives the combined packet P ₅ /C ₄ from the receiving means 22, the packet info identifier N/C of the combined packet P ₅ /C ₄ is "N" and the coded info identifier N/ It confirms that C consists of "C", determines that N packet PKT_N has not been received (see "NO" in step S22 of FIG. 14), and determines that a combined packet has been received (step S23 of FIG. 14). (see "YES" in ).

Thereafter, the processing means 23 separates the N packet _P5 and the encoded packet _C4 of the combined packet P5/ _{C4 (} see step S24 in FIG. 14), and determines that there are N packets (step S24 in FIG. 14). See "YES" in S25), N packet reception processing is executed for packet P5 ₍ see step S26 in FIG. 14). Then, in the N packet reception process, the processing means 23 determines that the sequence number SN _rx of the packet P5 has been received and the sequence number SN _sent of the N packet _{PKT_N} that has been transmitted to the application 30 (that is, and the received packet is not stored in the N buffer 24 (see "NO" in step S261 of FIG. ₁₅ ), and the packet P5 is stored in the N buffer 24. together with the packet P5 to the application 30 ₍ see steps S263 to S266 in FIG. 15). Then, when i=2, the processing means 23 determines that there is no packet of SN _sent +i (=SN _sent +2) in the N buffer 24 (see "NO" in step S265 of FIG. 15), and SN _Sent = SN _sent +i-1 = SN _sent +2-1 = SN _sent +1 updates the sequence number SN _sent of the N packet PKT_N stored in the N buffer 24 (see step S268 in FIG. 15). Thereafter, the processing means 23 determines that there is a C packet (see "YES" in step S27 of FIG. 14), and removes the information of the received N packets from the C packet (see step S28 of FIG. 14). At this point, packets P ₂ , P ₄ and P ₅ are stored in N buffer 24 (see (e) in FIG. 18), and encoded packet C ₄ includes packets P ₁ to P ₄ . , the processing means 23 sequentially performs an exclusive OR operation _on the encoded packet _C4 and the packets P2 and _P4 to remove the information of the already received packets P2 and _P4 from the encoded packet _{C4 (} (See steps S282 to S286 in FIG. 16).

The encoded packet C ₄ ′ after removing the information of the received packets P ₂ and P ₄ from the encoded packet C ₄ is represented by Equation (9). As a result, the processing means 23 determines that all the information contained in the encoded packet _C4 has not been received (see "NO" in step S287 in FIG. 16), and the encoded packet _C4 ' is not "1" (see "NO" in step S288 of FIG. 16), and the encoded packet C ₄ ' is stored in the C buffer 25 (see step S289 of FIG. 16). As a result, three packets P ₂ , P ₄ and P ₅ are stored in the N buffer 24, and one encoded packet C ₄ ′ is stored in the C buffer 25 ((e) in FIG. 18). )reference).

After step S289 in FIG. 16, the operation of the receiver 2 proceeds to step S29 in FIG. 14, and in step S291 in FIG. is not present in the C buffer 25, and the operation of the receiver 2 proceeds to step S21 in FIG.

After that, when transmitter ₁ transmits packet P6, receiver ₂ performs the same operation as when receiving packet P2 described above. As a result, packet _P6 is stored in N buffer 24 (see (f) in FIG. 18). After the packet _P6 is stored in the N buffer 24, the processing means 23 determines that there is no C packet (see "NO" in step S27 in FIG. 14). to step S21.

Subsequently, when the transmitter ₁ transmits the encoded packet C6, the receiving means 22 of the receiver ₂ receives the encoded packet C6 via the antenna 21 (see "YES" in step S21 of FIG. 14). , outputs the received encoded packet C ₆ to the processing means 23 .

When the processing means 23 receives the encoded packet _C6 from the receiving means 22, the identifier N/C of the _Packet info of the encoded packet C6 is "C", so it determines that N packets have not been received (Fig. 14), and determines that the combined packet has not been received (see "NO" in step S23 of FIG. 14).

Therefore, the processing means 23 removes the received packet information from the encoded packet C6 (see step S28 in FIG. ₁₄ ). At this stage, packets P ₂ , P ₄ , P ₅ and P ₆ are stored in N buffer 24, and encoded packet C ₆ includes packets P ₁ to P ₆ (see equation (6) ), the processing means 23 successively performs exclusive OR operations on the encoded packet C ₆ and the packets P ₂ , P ₄ , P ₅ and P ₆ to obtain the already received packets P ₂ and P from the encoded packet C ₆ . ₄ , P ₅ and P ₆ are removed (see steps S282 to S286 in FIG. 16).

The encoded packet C ₆ ′ after removing the information of the received packets P ₂ , P ₄ , P ₅ and P ₆ from the encoded packet C ₆ is represented by Equation (10). As a result, the processing means 23 determines that all the information contained in the encoded packet C6 has not been received (see "NO" in step _S287 of FIG. ₁₆ ), and the encoded packet C6 ' is not "1" (see "NO" in step S288 of FIG. 16), and stores the encoded packet C ₆ ' in the C buffer 25 (see step S289 of FIG. 16). As a result, the N buffer 24 stores four packets P ₂ , P ₄ , P ₅ and P ₆ , and the C buffer 25 stores two encoded packets C ₄ ′ and C ₆ ′. (See (g) of FIG. 18).

Then, the processing means 23 determines that there are a plurality of encoded packets including a plurality of N packets (see “YES” in step S299 of FIG. 17), and formula (9) representing the encoded packet C ₄ ′ and encoding Simultaneous equations with equation (10) representing packet C ₆ ′ are solved to decode C packet (see step S300 in FIG. 17). This results in two N packets P ₁ and P ₃ .

Thereafter, the processing means 23 sets i=1 (see step S301 in FIG. 17), and determines that the number of N packets that can be decoded is i (=1) or more ("YES" in step S302 in FIG. 17). (see step _S303 in FIG. 17). Then, in the N packet reception process, the processing means 23 determines that the sequence _number SN _rx of the packet P1 has been received and the sequence number SN _sent of the N packet PKT_N that has been transmitted to the application 30 (that is, and the received packet (=packet P ₁ ) is not stored in the N buffer 24 (see “NO” in step S261 in FIG. 15), and packet P ₁ is transferred to N While storing in the buffer 24, the packet P1 is transmitted to the application 30 (see steps S263 to S266 in FIG. ₁₅ ). Then, when i=2, the processing means 23 determines that there is no packet of SN _sent +i (=SN _sent +2) in the N buffer 24 (see "NO" in step S265 of FIG. 15), and SN _Sent = SN _sent +i-1 = SN _sent +2-1 = SN _sent +1 updates the sequence number SN _sent of the N packet PKT_N stored in the N buffer 24 (see step S268 in FIG. 15).

When the "N packet reception process" (flow chart shown in FIG. 15) is executed in step S303 of FIG. 17, the operation of the receiver 2 proceeds to step S304 of FIG. 15 after step S268 of FIG. , the processing means 23 sets i=i+1=2 (see step S304 in FIG. 17), and determines that the number of N packets that can be decoded is i (=2) or more ("YES" in step S302 in FIG. 17). ”), and the “N packet reception process” (flow chart shown in _FIG . 15) is executed for the N packet P2 (see step S303 in FIG. 17). Then, in the N packet reception process, the processing means 23 determines that the sequence _number SN _rx of the packet P2 has been received and the sequence number SN _sent of the N packet PKT_N that has been transmitted to the application 30 (that is, and the received packet (=packet P ₂ ) is not stored in the N buffer 24 (see “NO” in step S261 of FIG. 15), and packet P ₂ is transferred to N While storing in the buffer 24, the packet P2 is transmitted to the application 30 (see steps S263 to S266 in _FIG . 15). Then, when i=2, the processing means 23 determines that the packet of SN _sent +i (=SN _sent +2) does not exist in the N buffer 24 (see "NO" in step S265 of FIG. 15), _Sent = SN _sent +i-1 = SN _sent +2-1 = SN _sent +1 updates the sequence number SN _sent of the N packet PKT_N stored in the N buffer 24 (see step S268 in FIG. 15). After that, the processing means 23 sets i=i+1=3 (see step S304 in FIG. 17), and determines that the number of N packets that can be decoded is not equal to or greater than i (=3) ("NO in step S302 in FIG. 17"). "reference). Then, the operation of the receiver 2 proceeds to step S30 in FIG. 14, the processing means 23 determines that the decoding was successful ("YES" in step S30 in FIG. 14), and the detailed operation in step S29 in FIG. 17, it is determined that two or more encoded packets do not exist in the C buffer 25 (see "NO" in step S291 of FIG. 17), and the operation of the receiver 2 is as shown in FIG. The process proceeds to step S21.

At this stage, no packet is stored in the N buffer 24 and the C buffer 25 (see (h) in FIG. 18). This completes the reception processing of the packets (packets P ₁ to P ₆ ) forming the burst.

In the flowchart shown in FIG. 14 (including the flowcharts shown in FIGS. 15 to 17) showing the packet reception process, in step S28 of FIG. The reason for executing "removing the received packet _Xi information from the encoded packet" in step S294 of the flowchart of FIG. 17 showing the detailed operation of the decoding process in step S29 is as follows. according to.

In the flowchart of FIG. 12 showing the operation of the transmitter 1, when it is determined in step S9 that T milliseconds have passed since the last packet arrived in the buffer 11, the transmitter 1 performs the following in step S11: Encoded packets C are transmitted to the receiver 2 until it is determined that the number of transmitted encoded packets is K (see steps S10 to S12). In this case, as described above, the transmitter 1 transmits encoded packet C ₆ (=a ₆₁ P ₁ +a ₆₂ P ₂ +a ₆₃ P ₃ +a ₆₄ P ₄ +a ₆₅ P ₅ +a ₆₆ P ₆ ), encoded packet C ₇ (=a ₇₁ P ₁ +a ₇₂ P ₂ +a ₇₃ P ₃ +a ₇₄ P ₄ +a ₇₅ P ₅ +a ₇₆ P ₆ ) and encoded packet C ₈ (=a ₈₁ P ₁ +a ₈₂ P ₂ +a ₈₃ P ₃ +a ₈₄ P ₄ +a ₈₅ P ₅ +a ₈₆ P ₆ ) to receiver 2 . And here, the code a ₆₃ in the encoded packet C ₆ is assumed to be zero. That is, the encoded packet C ₆ is substantially composed of C ₆ =a ₆₁ P ₁ +a ₆₂ P ₂ +a ₆₄ P ₄ +a ₆₅ P ₅ +a ₆₆ P ₆ .

As a result, even if the receiver ₂ cannot receive the encoded packet C (for example, encoded packet C ₂ ) transmitted in step S7 of FIG. ₈ can be received.

Then, the processing means 23 of the receiver 2 determines that the N packet has not been received (see "NO" in step S22 of FIG. 14) and that the combined packet has not been received (step S23 of FIG. 14). "NO" in ), remove the information of the received N packets P ₂ , P ₄ , P ₅ and P ₆ from the encoded packet C ₆ (step S28 in FIG. 14 (step S261 to step S286) reference). As a result, the processing means 23 obtains the encoded packet C ₆ ′=a ₆₁ P ₁ .

Then, the processing means 23 determines that all the information contained in the encoded packet Y has not been received (see "NO" in step S287 in FIG. 16), and N packets contained in the encoded packet C ₆ ′ number is "1" (see "YES" in step S288 in FIG. 16), and the encoded packet C ₆ '=a ₆₁ P ₁ is converted to P ₁ by equation (13) to obtain "N packets received process” (flowchart shown in FIG. 15) is executed (see step S290 in FIG. 16).

In this case, the "N packet reception process" is executed for the _first time for the packet P1, so the processing means 23 receives the N packets whose sequence _number SN _rx of the packet P1 has been received and has been transmitted to the application 30. It is determined that the received packet (packet P 1 ) is larger than the sequence number SN _sent of PKT_N (that is, the sequence number of the N packets stored in the N buffer 24) and that the received packet (packet P ₁ ) has not been stored in the N buffer 24 (see FIG. 15). See "NO" in step S261), and packet P1 is stored in the N buffer 24 (see step S263 in FIG. ₁₅ ). At this stage, packets P ₁ , P ₂ , P ₄ , P ₅ and P ₆ are stored in N buffer 24 .

After step S290 in FIG. 16, the processing means 23 repeats steps S293 to S298 in the flowchart of FIG. 17 showing detailed operations of the decoding process (see step S29 in FIG. 14), In step S294, the information of packet P ₁ is removed from encoded packet C ₄ ′ (=a ₄₁ P ₁ +a ₄₃ P ₃ ) to create encoded packet C ₇ (=a ₇₁ P ₁ +a ₇₂ P ₂ +a ₇₃ P ₃ ). +a ₇₄ P ₄ +a ₇₅ P ₅ +a ₇₆ P ₆ ) to remove the information of packets P ₁ , P ₂ , P ₄ , P ₅ and P ₆ from the encoded packet C ₈ (=a ₈₁ P ₁ +a ₈₂ P ₂ +a ₈₃ P ₃ +a ₈₄ P ₄ +a ₈₅ P ₅ +a ₈₆ P ₆ ) remove the information of packets P ₁ , P ₂ , P ₄ , P ₅ and P ₆ .

Thus, in order to remove the information of the newly acquired packet P ₁ (N packets) from the encoded packets C ₄ ′, C ₇ and C ₈ , in step S28 of FIG. After executing "remove the information of the N packets of X _i from the encoded packet" in step S294 of the flowchart of FIG. I decided to do what I did.

In embodiments of the present invention, the operation of transmitter 1 may be realized by software. In this case, the transmitter 1 includes a CPU (Central Processing Unit), a ROM (Read Only Memory) and a RAM (Random Access Memory). The ROM stores a program Prog_A consisting of steps of the flowchart shown in FIG. 12 (including the flowchart shown in FIG. 13).

The CPU reads the program Prog_A from the ROM, executes the read program Prog_A, and executes the operation of transmitting the packet to the receiver 2 . The RAM serves the function of the buffer 11 described above.

Also, the program Prog_A may be recorded on a recording medium such as a CD or DVD and distributed. When the recording medium recording the program Prog_A is loaded into the computer, the computer reads the program Prog_A from the recording medium, executes it, and executes an operation of transmitting packets to the receiver 2 .

Therefore, the recording medium recording the program Prog_A is a computer-readable recording medium.

Also, in the embodiment of the present invention, the operation of the receiver 2 may be realized by software. In this case, the receiver 2 comprises a CPU, ROM and RAM. The ROM stores a program Prog_B consisting of steps of the flowchart shown in FIG. 14 (including the flowcharts shown in FIGS. 15 to 17).

The CPU reads the program Prog_B from the ROM and executes the read program Prog_B to perform packet reception processing. The RAM performs the functions of the N-buffer 24 and C-buffer 25 described above.

Also, the program Prog_B may be recorded on a recording medium such as a CD or DVD and distributed. When the recording medium recording the program Prog_B is loaded into the computer, the computer reads the program Prog_B from the recording medium and executes it to perform the packet reception process.

Therefore, the recording medium recording the program Prog_B is a computer-readable recording medium.

FIG. 19 is a schematic diagram of another wireless communication system according to embodiments of the invention. A radio communication system according to an embodiment of the present invention may be a radio communication system 10A shown in FIG.

Referring to FIG. 19, radio communication system 10A is obtained by replacing transmitter 1 of radio communication system 10 shown in FIG. be.

The transmitting device 100 includes a transmitter 1A and base stations AP_T_1 to AP_T_S (S is an integer of 2 or more).

The transmitter 1A has the same configuration as the transmitter 1 shown in FIG. The base stations AP_T_1 to AP_T_S are connected to the transmitter 1A via wired cables 3_1 to 3_S, respectively. The base stations AP_T_1 to AP_T_S are arranged so as to have communication ranges covering mutually different communication spaces in the communication space with the receiver 2 . In this case, the base stations AP_T_1 to AP_T_S are arranged at positions where radio waves are unlikely to be blocked by buildings or the like between the base stations AP_T_1 to AP_T_S.

Each time the transmitter 1A receives a packet PKT from the application 20 according to the flow chart shown in FIG. 12 (including the flow chart shown in FIG. 13), the transmitter 1A transmits a single packet or a combined packet to the wired cables 3_1 to 3_S by the method described above. , respectively to the base stations AP_T_1 to AP_T_S via the wired cables 3_1 to 3_S in the period in which the packet PKT is not received from the application 20, to the base stations AP_T_1 to AP_T_S, respectively.

The base stations AP_T_1 to AP_T_S receive single packets or combined packets from the transmitter 1A via wired cables 3_1 to 3_S, respectively, and receive the received single packets or combined packets via networks NW_1 to NW_S, respectively. Send to machine 2.

Also, the base stations AP_T_1 to AP_T_S receive encoded packets from the transmitter 1A via the wired cables 3_1 to 3_S, respectively, and transmit the received encoded packets to the receiver 2 via the networks NW_1 to NW_S, respectively. do.

In the radio communication system 10A, the receiver 2 receives single packets, combined packets, and encoded packets from the base stations AP_T_1 to AP_T_S via the networks NW_1 to NW_S, respectively. 15 to 17), the received single packet, combined packet, and encoded packet are subjected to the above-described reception processing, and the packet after the reception processing is transmitted to the application 30.

In the wireless communication system 10A, the transmitting device 100 transmits packets PKT (single packet, combined packet and encoded packet) to the receiver 2 by the base stations AP_T_1 to AP_T_S having mutually different communication ranges. 2, shielding of radio waves by buildings etc. can be suppressed, and packet PKT (single packet, combined packet and encoded packet) constituting real-time traffic can be quickly transmitted to receiver 2 with high reliability.

FIG. 20 is a schematic diagram of yet another wireless communication system according to an embodiment of the invention. A radio communication system according to an embodiment of the present invention may be a radio communication system 10B shown in FIG.

Referring to FIG. 20, radio communication system 10B is obtained by replacing receiver 2 of radio communication system 10 shown in FIG. be.

Receiving apparatus 200 includes base stations AP_R_1 to AP_R_S and a receiver 2A.

Receiver 2A has the same configuration as receiver 2 shown in FIG. The base stations AP_R_1 to AP_R_S are connected to the receiver 2A via wired cables 4_1 to 4_S, respectively. The base stations AP_R_1 to AP_R_S are arranged so as to have communication ranges covering mutually different communication spaces in the communication space with the transmitter 1 . In this case, the base stations AP_R_1 to AP_R_S are arranged at positions where radio waves are unlikely to be shielded by buildings or the like between the transmitter 1 and the base stations AP_R_1 to AP_R_S.

The base stations AP_R_1 to AP_R_S receive the packet PKT (single packet, combined packet and coded packet) via the networks NW_1 to NW_S, respectively, and convert the received packet PKT (single packet, combined packet and coded packet ) to the receiver 2A via the wired cables 4_1 to 4_S, respectively.

The receiver 2A receives the packet PKT (single packet, combined packet and encoded packet) via the wired cables 4_1 to 4_S, respectively, and includes the flow chart shown in FIG. 14 (flow charts shown in FIGS. 15 to 17). ), the received packet PKT (single packet, combined packet, and encoded packet) is subjected to the above-described reception processing, and the packet after the reception processing is transmitted to the application 30 .

In the wireless communication system 10B, the receiving device 200 receives the packet PKT (single packet, combined packet and encoded packet) from the transmitter 1 by the base stations AP_R_1 to AP_R_S having mutually different communication ranges. Shielding of radio waves by the transmission can be suppressed, and packet PKT (single packet, combined packet, and encoded packet) constituting real-time traffic can be received from the transmitter 1 quickly with high reliability.

FIG. 21 is a schematic diagram of yet another wireless communication system according to an embodiment of the invention. A radio communication system according to an embodiment of the present invention may be a radio communication system 10C shown in FIG.

Referring to FIG. 21 , radio communication system 10C includes transmitting device 100 and receiving device 200 . The configuration of transmitting apparatus 100 is as described with reference to FIG. Also, the configuration of the receiving device 200 is as described with reference to FIG.

In the radio communication system 10C, the base stations AP_T_1 to AP_T_S are provided corresponding to the base stations AP_R_1 to AP_R_S, respectively. As a result, the base station AP_T_1 and the base station AP_R_1 are placed at positions where they can transmit and receive packets PKT (single packet, combined packet and encoded packet) via a communication space with good communication performance. That is, since the base station AP_T_1 and the base station AP_R_1 perform one-to-one communication, the base station AP_T_1 can obtain good communication performance with the base station AP_R_1 without considering the arrangement positions of the base stations AP_R_2 to AP_R_S. The base station AP_R_1 is arranged at a position where good communication performance can be obtained with the base station AP_T_1 without considering the arrangement positions of the base stations AP_T_2 to AP_T_S. The same applies to base station AP_T_2 and base station AP_R_2, . . . , base station AP_T_S and base station AP_R_S.

Each time the transmitter 1A receives a packet PKT from the application 20 according to the flowchart shown in FIG. 12 (including the flowchart shown in FIG. 13), the transmitter 1A performs the above-described processing on the received packet PKT. Packets PKT (single packet, combined packet and encoded packet) are transmitted to base stations AP_T_1 to AP_T_S via wired cables 3_1 to 3_S.

The base station AP_T_1 receives a packet PKT (single packet, combined packet and coded packet) from the transmitter 1A via the wired cable 3_1, and converts the received packet PKT (single packet, combined packet and coded packet) to to the base station AP_R_1 via the network NW_1.

Also, the base station AP_T_2 receives a packet PKT (single packet, combined packet and encoded packet) from the transmitter 1A via the wired cable 3_2, and receives the received packet PKT (single packet, combined packet and encoded packet). packet) to the base station AP_R_2 via the network NW_2.

Similarly, base station AP_T_S receives packet PKT (single packet, combined packet and encoded packet) from transmitter 1A via wired cable 3_S, and receives packet PKT (single packet, combined packet). packets and encoded packets) to the base station AP_R_S via the network NW_S.

Base station AP_R_1 receives packet PKT (single packet, combined packet and encoded packet) from base station AP_T_1 via network NW_1, and converts the received packet PKT (single packet, combined packet and encoded packet) to It transmits to the receiver 2A via the wired cable 4_1.

Also, the base station AP_R_2 receives a packet PKT (single packet, combined packet and encoded packet) from the base station AP_T_2 via the network NW_2, and receives the received packet PKT (single packet, combined packet and encoded packet). ) to the receiver 2A via the wired cable 4_2.

Similarly, the base station AP_R_S receives a packet PKT (single packet, combined packet and encoded packet) from the base station AP_T_S via the network NW_S, and receives the received packet PKT (single packet, combined packet). and encoded packets) to the receiver 2A via the wired cable 4_S.

The receiver 2A receives packets PKT (single packet, combined packet and encoded packet) from the base stations AP_R_1 to AP_R_S via the wired cables 4_1 to 4_S, respectively. ), the received packet PKT (single packet, combined packet, and encoded packet) is subjected to the above-described reception processing, and the packet after the reception processing is transmitted to the application 30 .

In the wireless communication system 10C, packet PKT (single packet , combined packet and coded packet), it is possible to transmit and receive packet PKT (single packet, combined packet and coded packet) constituting real-time traffic more quickly and reliably than the wireless communication systems 10A and 10B.

FIG. 22 is a diagram showing another application example of the wireless communication system 10 shown in FIG. Referring to FIG. 22, receiver 2 and application 30 are placed in vehicles and trains. The transmitter 1 broadcasts packets PKT from the application 20 to vehicles and trains.

The receiver 2 receives the packet PKT from the transmitter 1 , executes reception processing, and then transmits the packet PKT to the application 30 . The application 30 reproduces the image and displays it on the display unit. This allows vehicle and train drivers to see the reproduced images in real time.

Further, the transmitter 1 described above may be installed in a base station, and the receiver 2 may be installed in a terminal device that receives packets from the base station within the communication range of the base station. As a result, the terminal device receives packets constituting real-time traffic transmitted from the base station with reduced delay, reproduces images included in the received packets, and displays them on the display unit. Therefore, the user of the terminal device can view the image in real time with high reliability.

In the above description, the transmitter 1 transmits an image to the receiver 2, but the embodiment of the present invention is not limited to this. A packet containing information other than an image in a payload may be transmitted to the receiver 2 as long as the packet is transmitted as a packet that does not contain images.

In the embodiment of the present invention, N packets constitute a "single packet", each of encoded packets C ₂ and C ₄ constitutes a "first encoded packet", and encoded packet C ₆ ˜C ₈ constitute a “second encoded packet”, after removing received packet information from encoded packets C ₄ , C ₆ , such as encoded packets C ₄ ′, C ₆ , constitutes a "third encoded packet".

Also, in the embodiment of the present invention, _each of P2/ _{C1 , P3} / _{C2 , P4} /C3, _P5 / _C4 , and _P6 /C5 constitutes a "combined packet". do.

Furthermore, in the embodiment of the present invention, the process of transmitting N packets constitutes " _first transmission process", and P2/C1 _{, P3} / _{C2 , P4} /C3, _P5 /C ₄ , P ₆ /C ₅ constitutes a "second transmission process", and the process of transmitting each of the encoded packets C ₆ to C ₈ alone constitutes a "third transmission process". Configure "Send Processing".

Furthermore, T milliseconds constitutes a "threshold" in embodiments of the present invention.

Furthermore, in the embodiment of the present invention, the N-buffer 24 constitutes a "first receive buffer" and the C-buffer 25 constitutes a "second receive buffer".

Further, in the embodiment of the present invention, P ₃ /C ₂ is separated into packet P ₃ and encoded packet C ₂ , P ₅ /C ₄ is separated into packet P ₅ and encoded packet C ₄ , P The processing means 23 for separating ₆ / _C5 into packets _P6 and encoded packets _C5 constitute "separating means".

Furthermore, in the embodiment of the present _invention , in _{step S261} of FIG. , and for transmitting the packets stored in the N-buffer 24 to the application 30 constitutes "first processing means".

Furthermore, in the embodiment of the present invention, generating the encoded packets C ₄ ′ and C ₆ ′ by removing the information of the received packets from the encoded packet C is performed by removing the information of the packets not stored in the N buffer 24 . is equivalent to generating an encoded packet containing only packets of . The processing means 23 for generating the encoded packets C ₄ ′ and C ₆ ′ by removing the information of the received packets from the encoded packet C constitutes the “second processing means”.

Furthermore, in the embodiment of the present invention, the processing means 23 for executing the decoding process in step S29 of FIG. 14 constitutes "decoding means".

Furthermore, in the embodiment of the present invention, the transmitter 1 shown in FIG. 1 constitutes a "transmitting device", and the receiver 2 shown in FIG. 1 constitutes a "receiving device". Therefore, the transmitter according to the embodiment of the present invention is composed of the transmitter 1 or the transmitter 100, and the receiver according to the embodiment of the invention is composed of the receiver 2 or the receiver 200. FIG.

It should be considered that the embodiments disclosed this time are illustrative in all respects and not restrictive. The scope of the present invention is indicated by the scope of the claims rather than the description of the above-described embodiments, and is intended to include all modifications within the scope and meaning equivalent to the scope of the claims.

INDUSTRIAL APPLICABILITY The present invention is applied to a transmitting device, a receiving device, a wireless communication system provided with these devices, a program, and a computer-readable recording medium recording the program.

1, 1A transmitter, 2, 2A receiver, 10, 10A, 10B, 10C wireless communication system, 11 buffer, 12, 23 processing means, 13 transmission means, 14, 21 antenna, 22 reception means, 24 N buffer, 25 C buffer, 20, 30 application, 100 transmitter, 200 receiver.

Claims (21)

A transmitting device that receives packets constituting real-time traffic from an application and transmits the received packets,
a transmission buffer for storing packets for transmission;
a processing means for performing transmission processing on the packet;
a transmitting means for transmitting the packet received from the processing means;
When the packet is the first simple packet arriving at the transmitting device at a first time interval, the processing means converts the first simple packet when the first simple packet arrives at the transmitting device. performing a first process of copying to the transmission buffer and outputting the first single packet to the transmission means, wherein the packets are continuously transmitted at a second time interval shorter than the first time interval; When the plurality of single packets arrive at the transmitting device, a second single packet selected from single packets other than the single packet arriving at the transmitting device first among the plurality of single packets arrives at the transmitting device. Then, the second simple packet is copied to the transmission buffer, and the first encoded packet including the simple packet that arrived at the transmitting device earlier than the second simple packet is added to the second simple packet. and performing a second process of generating a combined packet and outputting the combined packet to the transmission means, and performing a second process of outputting the combined packet to the transmission means, and a third unit packet which is included in the plurality of single packets and is a single packet other than the second single packet. arrives at the transmission device, the first processing is performed on the third single packet, and it is determined that the last single packet among the plurality of single packets has arrived at the transmission device. Then, the last single packet is copied to the transmission buffer, and when the last single packet corresponds to the second single packet, the second processing is performed on the last single packet, and the last single packet is copied to the transmission buffer. corresponds to the third single packet, the first processing is performed on the last single packet, and a predetermined time is determined from the timing when it is determined that the last single packet has arrived at the transmitting device. After a lapse of time, executing a third process of generating a second encoded packet including all the single packets stored in the transmission buffer and outputting the second encoded packet to the transmission means;
The transmission means, when receiving the first single packet from the processing means, executes a first transmission process of transmitting the received first single packet alone, and receives the combined packet from the processing means. Then, a second transmission process for transmitting the received combined packet is executed, and when the third single packet or the last single packet is received from the processing means, the received third single packet or the last single packet is transmitted. executing a first transmission process for a single packet, and when receiving the second encoded packet from the processing means, executing a third transmission process for transmitting the received second encoded packet alone; send device. The processing means, in the second processing,
When a fourth simplex packet, which is the simplex packet arriving at the transmitting apparatus last among the simplex packets arriving at the transmitting apparatus earlier than the second simplex packet or the last simplex packet, arrives at the transmitting apparatus. , after the fourth single packet is transmitted by the transmitting means, the first encoded packet including the single packet that arrived at the transmitting device earlier than the second single packet or the last single packet; and when the second simple packet or the last simple packet arrives at the transmission device after the first sub-process is executed, the first encoded packet is 2. The transmitting apparatus according to claim 1, which executes a second sub-process of adding said second unitary packet or said last unitary packet to generate said combined packet and outputting it to said transmitting means. The processing means, in the second processing, when the second unitary packet consists of a unitary packets (a is an integer equal to or greater than 1), for each of the a unitary packets, 3. The transmitting device according to claim 2, which performs said first and second sub-processes. The processing means sets the initial value of the encoded packet to Y ₀ having a predetermined length of zeros, and converts the packet extracted from the transmission buffer to X _i (i=1, 2, . . . , I, I is total number of packets stored in the transmission buffer when the first encoded packet or the second encoded packet is generated ₎ , a random number of a predetermined length is Ci, and an encoded packet is _Yi , the packet X _i is multiplied by the random number C _i of the predetermined length, and the result of multiplication C _i ·X _i and Y _i−1 are exclusive ORed for all i. 4. The transmitting apparatus according to any one of claims 1 to 3, wherein the encoded packet _Yi is generated as the first encoded packet or the second encoded packet. Further comprising a plurality of base stations connected to the transmitting means by wired cables,
The plurality of base stations receive the first single packet, the combined packet, the third single packet, the last single packet and the second encoded packet from the transmitting means via the wired cable. and transmitting the received first simple packet, the combined packet, the third simple packet, the last simple packet and the second encoded packet through mutually different communication paths. 1. The transmitter according to claim 1. A receiving device for receiving a packet from the transmitting device according to any one of claims 1 to 5,
a first receive buffer for storing single packets;
a second receive buffer for storing encoded packets;
receiving means for receiving the first and third simple packets, the combined packet, and the second encoded packet;
separating means for separating the combined packet into the first encoded packet and the second single packet;
storing in the first reception buffer a single packet that has not been stored in the first reception buffer or that has not been received from the first single packet or the third single packet; first processing means for executing a reception process of transmitting the single packet stored in the reception buffer to an application that uses the information transmitted by the packet from the transmission device;
generating a third encoded packet containing only a plurality of single packets not stored in the first reception buffer, based on the encoded packet received by the receiving means, and performing the generated third encoded packet; second processing means for executing a process of storing packets in the second reception buffer for all of the first and second encoded packets;
Decoding for reading the plurality of third encoded packets from the second reception buffer and solving simultaneous equations for the read plurality of third encoded packets to decode the plurality of third encoded packets and decryption means for performing processing,
The receiving device, wherein the first processing means further executes the receiving process on the single packet decoded by the decoding means. wherein said second processing means generates said third encoded packet by removing information of a single packet stored in said first reception buffer from said encoded packet received by said receiving means. Item 7. The receiving device according to item 6. When the second processing means determines that the single packet stored in the first reception buffer is included in the encoded packet received by the receiving means, the encoded packet received by the receiving means 8. The receiving device according to claim 7, which generates said third encoded packet. When the encoded packet obtained by removing the information of the single packet stored in the first reception buffer from the encoded packet received by the receiving means includes one single packet, the second processing means , further erasing the encoded packet including the single packet from the second receive buffer;
9. The first processing means according to claim 7, wherein said first processing means converts an encoded packet including said one single packet into a single packet, and executes said reception processing on the converted single packet. receiver. further comprising a plurality of base stations connected to the receiving means by a wired cable and receiving packets transmitted from the transmitting device via a plurality of mutually different communication paths;
10. The receiving apparatus according to any one of claims 6 to 9, wherein each of said plurality of base stations outputs said received packet to said receiving means via said wired cable. a transmitter according to any one of claims 1 to 5;
A radio communication system comprising the receiving device according to any one of claims 6 to 10. A program for causing a computer to execute transmission of packets in a transmission device that receives packets constituting real-time traffic from an application,
a first step in which a processing means performs processing for transmission on the packet;
causing the computer to execute a second step in which the transmitting means transmits the packet received from the processing means;
The processing means, in the first step, when the packet is a first single packet arriving at the transmitting device at a first time interval, when the first single packet arrives at the transmitting device, executing a first process of copying the first single packet to a transmission buffer for storing a packet for transmission and outputting the first single packet to the transmitting means, wherein the packet is the first single packet; When a plurality of single packets arrive at the transmitting device continuously at a second time interval shorter than the time interval, a single packet other than the single packet arriving at the transmitting device first among the plurality of single packets. When a second simplex packet selected from arrives at the transmitting device, copying the second simplex packet to the transmission buffer, including simplex packets arriving at the transmitting device earlier than the second simplex packet. performing a second process of generating a combined packet by adding a first encoded packet to the second single packet and outputting the combined packet to the transmitting means, wherein the unit packet is included in the plurality of single packets; , when a third single packet which is a single packet other than the second single packet arrives at the transmitting device, the first processing is performed on the third single packet, and the plurality of single packets are processed. When it is determined that the last single packet has arrived at the transmitting device, the last single packet is copied to the transmission buffer, and when the last single packet corresponds to the second single packet, the last single packet is obtained. performing the second processing on the packet, performing the first processing on the last single packet when the last single packet corresponds to the third single packet, and performing the last single packet; generating a second encoded packet including all single packets stored in the transmission buffer and outputting the second encoded packet to the transmission means when a predetermined time has elapsed from the timing at which it is determined that the packet has arrived at the transmission device; Execute the process of 3,
The transmitting means, in the second step, when receiving the first single packet from the processing means, performs a first transmission process of transmitting the received first single packet independently, and When a packet is received from the processing means, a second transmission process for transmitting the received combined packet is executed, and when the third single packet or the last single packet is received from the processing means, the received second performing the first transmission processing on the 3 single packets or the last single packet, and upon receiving the second encoded packet from the processing means, transmitting the received second encoded packet alone; A program for causing a computer to execute a third transmission process. The processing means, in the second processing of the first step,
When a fourth simplex packet, which is the simplex packet arriving at the transmitting apparatus last among the simplex packets arriving at the transmitting apparatus earlier than the second simplex packet or the last simplex packet, arrives at the transmitting apparatus. , after the fourth simple packet is transmitted by the transmitting means, the first encoded packet including the simple packet which arrived at the transmitting device earlier than the second simple packet or the last simple packet; and when the second simplex packet or the final simplex packet arrives at the transmitting device after the first subprocess is executed, the first encoded packet is 13. The method for causing a computer according to claim 12 to execute a second sub-process of adding to said second unitary packet or said last unitary packet to generate said combined packet and outputting it to said transmitting means. program. The processing means, in the second processing of the first step, when the second single packet consists of a single packets (a is an integer equal to or greater than 1), the a number of single packets 14. The program for execution by a computer according to claim 13, wherein said first and second sub-processes are executed for each single packet. The processing means sets the initial value of the encoded packet to Y ₀ having a predetermined length of zeros, and converts the packet extracted from the transmission buffer to X _i (i=1, 2, . . . , I, I is total number of packets stored in the transmission buffer when the first encoded packet or the second encoded packet is generated ₎ , a random number of a predetermined length is Ci, and an encoded packet is _Yi , the packet X _i is multiplied by the random number C _i of the predetermined length, and the result of multiplication C _i ·X _i and Y _i−1 are exclusive ORed for all i. 15. The program according to any one of claims 12 to 14, which generates the encoded packet _Yi as the first encoded packet or the second encoded packet. In the second step, the transmitting means transmits the first single packet, the combined packet, the third single packet, the last single packet and the second encoded packet via a wired cable. transmit to multiple base stations,
The plurality of base stations receive the first single packet, the combined packet, the third single packet, the last single packet and the second encoded packet from the transmitting means via the wired cable. and transmitting the received first simple packet, the combined packet, the third simple packet, the last simple packet and the second coded packet through mutually different communication paths. 1. A program to be executed by the computer according to 1. A program for causing a computer to receive a packet transmitted by causing a computer to execute the program according to any one of claims 12 to 16,
a first step in which receiving means receives said first and third simplex packets, said combined packet and said second encoded packet;
a second step in which the separating means separates the combined packet into the first encoded packet and the second simple packet;
A first processing means stores, in the first reception buffer, a single packet which is not stored in the first reception buffer or which has not been received among the first single packet or the third single packet. a third step of executing a reception process for transmitting the single packet stored in the first reception buffer to an application that uses the information transmitted by the packet;
A second processing means generates a third encoded packet including only a plurality of single packets not stored in the first reception buffer, based on the encoded packet received in the first step. a fourth step of storing the generated third encoded packet in a second reception buffer for all of the first and second encoded packets;
Decoding means reads the plurality of third encoded packets from the second reception buffer and solves simultaneous equations for the read plurality of third encoded packets to obtain the plurality of third encoded packets. cause the computer to execute a fifth step of executing a decryption process of decrypting the
A program to be executed by a computer, wherein the first processing means further executes the receiving process on the single packet decoded by the decoding means in the third step. The second processing means, in the fourth step, removes the information of the single packet stored in the first reception buffer from the encoded packet received in the first step, thereby performing the third processing. 18. A program for computer execution according to claim 17, which generates an encoded packet of . When the second processing means determines in the fourth step that the single packet stored in the first reception buffer is included in the encoded packet received in the first step, the second processing means 19. The program for computer execution of claim 18, wherein the third encoded packet is generated from the encoded packet received in step 1. The second processing means, in the fourth step, the encoded packet after removing the information of the single packet stored in the first reception buffer from the encoded packet received in the first step. contains one simplex packet, further clearing the encoded packet containing the single simplex packet from the first receive buffer;
3. The first processing means, in the third step, converts the encoded packet including the single unit packet into a unit packet, and executes the reception processing on the unit packet thus converted. A program to be executed by the computer according to claim 18 or 19. A computer-readable recording medium recording the program according to any one of claims 12 to 20.

Images