JP2006245781A - Data transmission/reception system and data transmission method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To achieve error correction of data received by the reception side while reducing a data amount transmitted from the transmission side to the reception side compared with a conventional data transmission/reception system. <P>SOLUTION: A multimedia data distribution device 1 is provided with a data transmission means for transmitting data to a terminal device 2, and a means for discriminating whether or not errors occur in the data received by the terminal device 2. The terminal device 2 is provided with a means for receiving the data from the data distribution device 1, a means for generating an error detection code of the received data, and an error detection code transmission means for transmitting the generated error detection code to the multimedia data distribution device 1. A means for discriminating the presence or the absence of errors discriminates whether or not the errors occur in the multimedia data received by the terminal device 2 on the basis of the error detection code transmitted from the terminal device 2. The data transmission means retransmits the multimedia data to the terminal device 2 when it is discriminated that the errors occur in the multimedia data received by the terminal device 2. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a system and method for transmitting and receiving data.

  When data is exchanged between two devices, part of the data is damaged due to noise on the communication path, and the data that reaches the receiving device contains errors. There is. If the apparatus on the receiving side uses the data containing the error as it is and executes processing, it may cause a problem.

  Therefore, a method as described in Non-Patent Document 1 has been proposed. According to this method, the transmission-side apparatus transmits data to be transmitted to the reception-side apparatus together with an error detection code such as a CRC code. The receiving apparatus determines whether or not an error has occurred in the received data by performing arithmetic processing using the error detection code. If it is determined that an error has occurred, the transmission side apparatus is requested to transmit the data again.

  In addition, a method using an error correction code such as an ECC (Error Check and Correct) code as described in Non-Patent Document 2 has been proposed. The transmission-side apparatus transmits the transmission target data to the reception-side apparatus together with the error correction code. Then, the receiving device performs an arithmetic process using the error correction code, thereby detecting an error in the received data and correcting the error if there is an error.

By the way, in recent years, the performance of various resources has improved, such as the processing speed of the CPU has increased, the capacity of the memory has increased, and the resolution of the display has increased. The amount of data being processed is increasing. Therefore, the amount of data exchanged between devices is also increasing. With the development of communication technology, the speed of communication is becoming faster and faster, but effective use of communication lines is indispensable in order to maximize the performance of resources such as CPU.
"Research on Adaptive Type-I Hybrid ARQ System Suitable for Mobile Computing", "Kenji Nakamura, Norio Ishii, Hiroyuki Mishima", searched on January 28, 2005, Internet <URL: http: // www. nak.nw.kanagawa-it.ac.jp/thesis/1998/arq-1998.pdf> “Solution to Fujitsu NAND Flash Memory (Information Magazine“ FIND ”vol.19 No.1 2001)”, published by Electronic Device Sales Division, Fujitsu Limited, searched on January 28, 2005, Internet <URL: http: / /edevice.fujitsu.com/jp/catalog/find/19-1j/pdf/j19-1-2.pdf>

  However, re-transmission of data increases traffic on a channel from the transmission side to the reception side (hereinafter referred to as “downlink channel”), which may cause a delay in data transfer. According to the method of self-correcting the error at the receiving apparatus using an error correction code such as an ECC code, there is no need to retransmit data. However, since error correction codes have high redundancy in the first place, if such a method is employed, traffic on the downlink channel becomes larger than when parity codes or CRC codes are used.

  In order to effectively use the downlink channel, it is most ideal to reduce the traffic by eliminating the error detection code or the error correction code by completely eliminating the occurrence of errors. However, it is extremely difficult to completely eliminate the occurrence of errors. Therefore, in order to maintain the reliability and accuracy of data, it is required to detect an error and correct it or perform data transmission / reception again.

  In view of these points, the present invention corrects an error occurring in data received by a receiving device while reducing the amount of data transmitted from the transmitting device to the receiving device. It is an object of the present invention to be able to perform processing for the purpose.

  A data transmission / reception system according to the present invention includes a first device and a second device, wherein the first device includes data transmission means for transmitting data to the second device, and the second device. An error presence / absence determining means for determining whether or not an error has occurred in the data received by the apparatus, and the second apparatus has a data receiving means for receiving the data from the first apparatus And an error detection code generation means for generating an error detection code for the data received from the first device, and an error detection code transmission means for transmitting the generated error detection code to the first device. The error presence / absence determining means determines whether or not an error has occurred in the data received by the second device based on the error detection code transmitted from the second device; The data transmission means includes the If an error in the data and second device receives is determined to have occurred, the data re-transmitted to the second device, and wherein the.

  Alternatively, the first device includes an error detection code generation means for generating an error detection code of target data that is target data to be transmitted to the second device, and the target data together with the error detection code. Target data transmitting means for transmitting to a second device, error part determining means for determining an error part that is an error part from the target data received by the second device, and the error determining means Correction data transmitting means for transmitting correction data for correcting the error portion determined by the second device to the second device, and the second device from the first device to the second device Objective data receiving means for receiving objective data together with the error detection code, and whether or not an error has occurred in the received objective data, the error detection code received together with the objective data. And determining whether there is an error in the received target data, and transmitting the target data to the first device as check data when it is determined that an error has occurred. Data transmission means, and the error part determination means transmits the error part of the target data received by the second apparatus to the second apparatus by the target data transmission means. And the check data transmitted from the second device are compared with each other.

  As the error detection code, for example, a CRC (Cyclic Redundancy Check) code or a parity code is used.

  According to the present invention, processing for correcting an error occurring in data received by a receiving device is performed while reducing the amount of data transmitted from the transmitting device to the receiving device. Can do.

[First embodiment]
1 is a diagram showing an example of the overall configuration of a network system NWS according to the present invention, FIG. 2 is a diagram showing an example of a hardware configuration of a multimedia data distribution apparatus 1, and FIG. 3 is a hardware configuration of a terminal apparatus 2. It is a figure which shows the example of.

  As shown in FIG. 1, the network system NWS according to the present invention includes a multimedia data distribution device 1, a terminal device 2, a communication line 3, and the like. The multimedia data distribution device 1 and the terminal device 2 are connected to each other via a communication line 3 and transmit multimedia data to the terminal device 2 in response to a request from a user.

  As the communication line 3, the downlink direction (direction from the multimedia data distribution device 1 to the terminal device 2) and the uplink direction (from the terminal device 2 to the multimedia data distribution device 1) such as Ethernet or ADSL (Asymmetric Digital Subscriber Line) are used. The communication line provided with each channel is used. Hereinafter, the downlink channel is referred to as “downlink CHd”, and the uplink channel is referred to as “uplink CHu”. The downlink channel CHd and the uplink channel CHu may be realized by time division multiplexing or frequency multiplexing (band division), or may be realized by preparing two physical lines.

  As shown in FIG. 2, the multimedia data distribution apparatus 1 includes a CPU 10a, a RAM 10b, a ROM 10c, a DVD (Digital Versatile Disc) drive 10d, a hard disk 10e, a data transmission unit 1S, a data reception unit 1R, and the like.

  The ROM 10c and the hard disk 10e store programs and data for controlling each part of the multimedia data distribution apparatus 1. These programs and data are loaded into the RAM 10b as necessary, and the programs are executed by the CPU 10a.

  Further, the hard disk 10e stores multimedia data GDT of various types of multimedia contents such as movies, plays, sports, and news. These multimedia data GDT are distributed (transmitted) to the terminal device 2 in response to a request from the user of the terminal device 2. Also, the multimedia data GDT recorded on the disc can be read by the DVD drive 10d and transmitted to the terminal device 2. For example, MPEG (Moving Picture Experts Group) is used as the format of the multimedia data GDT.

  The data transmission unit 1S includes a block generation circuit 101, a transmission circuit 102, a transmitted data buffer 103, a retry transmission control circuit 104, and the like, and performs processing for transmitting multimedia data GDT to the terminal device 2.

  The data reception unit 1R includes a reception circuit 121, a reception data buffer 122, a check data generation circuit 123, a check data comparison circuit 124, and the like, receives control data from the terminal device 2, and receives multimedia data GDT. A process of checking whether or not re-transmission of a part (block BL1 described later) is necessary is performed.

  The processing contents of each circuit of the data transmission unit 1S and the data reception unit 1R will be described in detail later. Note that some functions of the data transmission unit 1S and the data reception unit 1R may be realized by software by a program.

  As the multimedia data distribution apparatus 1, for example, a personal computer or a workstation connected with a DVD playback apparatus is used. Alternatively, a DVD player having a network function or a player with a built-in hard disk may be used.

  As shown in FIG. 3, the terminal device 2 includes a terminal device body 2M, an input device 2N such as a keyboard or a mouse, a display 2D, and a speaker 2P.

  The terminal device body 2M includes a CPU 20a, a RAM 20b, a ROM 20c, a hard disk 20d, a video interface 20e, an input interface 20f, an audio interface 20g, a data transmission unit 2S, a data reception unit 2R, and the like.

  The ROM 20c and the hard disk 20d store programs and data for controlling each part of the terminal device body 2M, the display 2D, the input device 2N, and the speaker 2P. These programs and data are loaded into the RAM 20b as necessary, and the programs are executed by the CPU 20a. Further, the hard disk 20d is installed with application software for reproducing multimedia contents, that is, video and audio, based on the multimedia data GDT received from the multimedia data distribution apparatus 1, and outputting the same through the display 2D and the speaker 2P. Yes.

  The video interface 20e, the input interface 20f, and the audio interface 20g are interfaces for connecting to the display 2D, the input device 2N, and the speaker 2P, respectively.

  The data transmission unit 2S includes a control data generation circuit 201, a transmission circuit 202, a transmitted data buffer 203, and the like, and performs processing for transmitting control data to the multimedia data distribution apparatus 1.

  The data reception unit 2R includes a reception circuit 221, a reception data buffer 222, a check data generation circuit 223, a block combination circuit 224, and the like, and receives multimedia data GDT distributed from the multimedia data distribution device 1. Perform the process.

  The processing contents of each circuit of the data transmission unit 2S and the data reception unit 2R will be sequentially described in detail. Note that some functions of the data transmission unit 2S and the data reception unit 2R may be realized by software by a program. As the terminal device 2, a personal computer or a workstation is used.

  4 is a diagram illustrating an example of the configuration and generation method of the block BL1, FIG. 5 is a diagram illustrating an example of the configuration and generation method of the retransmission control data BL2, and FIG. 6 is an error detection method of the divided data BDT. It is a figure explaining an example.

  Hereinafter, the processing contents of the data transmission unit 1S and the data reception unit 1R illustrated in FIG. 2 and the data transmission unit 2S and the data reception unit 2R illustrated in FIG. 3 will be described in detail.

  In the multimedia data distribution apparatus 1 of FIG. 2, the block generation circuit 101 of the data transmission unit 1S reads the multimedia data GDT of the multimedia content requested by the user, read from the DVD drive 10d or the hard disk 10e. As shown in (a), the data is divided into data having a predetermined data length. Hereinafter, the divided data of the multimedia data GDT is referred to as “divided data BDT”.

  As shown in FIG. 4B, sequence numbers “1”, “2”,... Are added to the divided data BDT in order from the top, and a protocol for communication between the multimedia data distribution device 1 and the terminal device 2 is added. The block BL1 is generated by attaching a transmission destination address, a transmission source address, a data type, or the like according to the above. Here, the address on the network of the requesting terminal device 2 is described in the transmission destination address, the address on the network of the multimedia data distribution device 1 itself is described in the transmission source address, and the multimedia data is stored in the data type. Note that the data is divided data.

  The transmission circuit 102 transmits the block BL1 generated by the block generation circuit 101 to the transmission destination address, that is, the requesting terminal device 2.

  The transmitted data buffer 103 temporarily stores the block BL1 transmitted by the transmission circuit 102. When the free space of the transmitted data buffer 103 becomes insufficient, the free space is secured by deleting sequentially from the block BL1 with the smallest sequence number (that is, the old one).

  The retry transmission control circuit 104 retransmits the block BL1 when the data reception unit 1R detects that there is an error (error) in the divided data BDT in the block BL1 received by the terminal device 2. Control processing is performed. The contents of such control processing will be described later.

  In the terminal device 2 of FIG. 3, the receiving circuit 221 of the data receiving unit 2R receives the block BL1 transmitted from the multimedia data distribution device 1.

  The received block BL1 is stored in the reception data buffer 222. Of the data included in the block BL1, data that is no longer used may be deleted upon reception. When the free space of the reception data buffer 222 becomes insufficient, the free space is secured by deleting in order from the block BL1 with the smallest sequence number. Alternatively, when a predetermined time elapses after reception, it may be deleted regardless of the free space.

  In addition, when the multimedia data distribution apparatus 1 detects that the divided data BDT included in the received block BL1 has an error, the divided data BDT is retransmitted. In this case, the retransmitted divided data BDT is stored in the received data buffer 222, and the older divided data BDT is deleted from the received data buffer 222.

  As shown in FIGS. 5A and 5B, the check data generation circuit 223 extracts the divided data BDT from the received block BL1, and generates data for error detection of the divided data BDT. Hereinafter, such data is referred to as “check data CKD”. As a method for generating the check data CKD, a CRC (Cyclic Redundancy Check) method, a parity check method, or the like is used. That is, in the case of the CRC method, a CRC code is generated as the check data CKD, and in the case of the parity check method, a parity code including a predetermined number of parity bits is generated.

  The generated check data CKD is transmitted to the multimedia data distribution apparatus 1 by the data transmission unit 2S and used for error detection of the divided data BDT, as will be described later.

  The block combining circuit 224 performs processing for restoring the multimedia data GDT divided by the multimedia data distribution apparatus 1 by combining the divided data BDT of each block BL1 stored in the reception data buffer 222 in the order of the sequence numbers. I do. However, when an error is included in the divided data BDT of the block BL1 stored in the reception data buffer 222, the block BL1 is retransmitted after a while. Therefore, the process of combining the divided data BDT is not performed immediately after receiving the divided data BDT, but after waiting for a predetermined time.

  As shown in FIG. 5C, the control data generation circuit 201 of the data transmission unit 2S adds the check data CKD to the check data CKD generated by the transmitted data buffer 203 of the data reception unit 2R. A sequence number of the divided data BDT is attached, and further a transmission destination address (here, an address on the network of the multimedia data distribution apparatus 1 that transmitted the divided data BDT that is the basis of the check data CKD) according to a protocol or the like The retransmission control data BL2 is generated by attaching a transmission source address or a data type.

  The transmission circuit 202 transmits the retransmission control data BL2 generated by the control data generation circuit 201 to the device indicated by the transmission destination address, that is, the multimedia data distribution device 1. Also, when a multimedia content playback request is made by the user, the multimedia content identification information, the network address of the requesting device (that is, the terminal device 2), the data type, and the like Is transmitted to the multimedia data distribution apparatus 1.

  The transmitted data buffer 203 temporarily stores retransmission control data BL2 transmitted to the multimedia data distribution apparatus 1 and the like.

  In the multimedia data distribution device 1 of FIG. 2, the check data generation circuit 123 of the data reception unit 1R acquires the block BL1 that has been transmitted to the terminal device 2 from the data transmission unit 1S, and the divided data BDT included therein Data for error detection is generated by the same method as the method for generating the check data CKD in the check data generation circuit 223 (see FIG. 3) of the terminal device 2. By using the same generation method in this way, the format of the error detection data generated by the check data generation circuit 123 is the same as that of the check data CKD generated by the check data generation circuit 223. . Hereinafter, the error detection data generated by the check data generation circuit 123 is referred to as “check data CKD ′”.

  The receiving circuit 121 receives various data transmitted from the terminal device 2. After reception, it is determined with reference to the data type of the data whether the data is retransmission control data BL2 or request data RCD.

  The check data CKD included in the retransmission control data BL2 has no error in the divided data BDT that has arrived at the terminal device 2 together with the check data CKD ′ generated by the check data generation circuit 123. Used for checking whether or not. Such processing is performed by the check data comparison circuit 124. Since the check data comparison circuit 124 is busy and the check data CKD of the received retransmission control data BL2 is not immediately used, the retransmission control data BL2 is stored in the reception data buffer 122.

  Here, the flow of error detection processing in the data receiving unit 1R will be described with reference to FIG. The check data comparison circuit 124 calls the retransmission control data BL2 stored in the reception data buffer 122 (# 301), and extracts the check data CKD included therein (# 302). However, when a plurality of retransmission control data BL2 are stored, they are called preferentially in ascending order of sequence number. If the retransmission control data BL2 is not stored, the check data CKD is extracted from the retransmission control data BL2 immediately after the new retransmission control data BL2 is received.

  The check data generation circuit 123 calls the block BL1 having the same sequence number as the retransmission control data BL2 from the transmitted data buffer 103 of the data transmission unit 1S (# 303), and the divided data BDT included in the block BL1. Check data CKD ′ is generated (# 304). The check data CKD ′ may be generated immediately after the block BL1 is transmitted to the terminal device 2, and may be stored in advance in the transmitted data buffer 103 or other storage means in association with the sequence number or the like. .

  Then, the check data comparison circuit 124 compares the check data CKD extracted in step # 302 with the check data CKD ′ generated in step # 304, so that the divided data BDT of the sequence number has an error. It is determined whether or not the terminal device 2 has received the message (# 305). That is, if the two match, it is determined that the message has been received without causing an error. If they do not match, it is determined that an error has occurred in the divided data BDT received by the terminal device 2.

  Returning to FIG. 2, when the data received by the receiving circuit 121 is the request data RCD, the multimedia data GDT of the multimedia content indicated in the request data RCD is called by the DVD drive 10d or the hard disk 10e. Then, as described above, the block generation circuit 101 and the transmission circuit 102 perform processing for transmitting the multimedia data GDT to the requesting terminal device 2.

  The retry transmission control circuit 104 of the data transmission unit 1S performs processing for retransmission of the divided data BDT, based on the determination result by the check data comparison circuit 124. When it is determined that an error has occurred in the divided data BDT, an instruction to transmit the divided data BDT to the terminal device 2 again is given to the transmission circuit 102. In response to the instruction, the transmission circuit 102 calls the block BL1 including the divided data BDT from the transmitted data buffer 103 and performs transmission to the terminal device 2 again. On the other hand, when it is determined that the divided data BDT has been received by the terminal device 2 without causing an error, the process for retransmission is not performed, and the block BL1 including the divided data BDT is deleted from the transmitted data buffer 103. Keep it.

  FIG. 7 is a flowchart for explaining an example of the overall processing flow of the multimedia data distribution apparatus 1 and the terminal apparatus 2.

  Next, the processing flow of both apparatuses when distributing multimedia data GDT of multimedia contents desired by the user from the multimedia data distribution apparatus 1 to the terminal apparatus 2 will be described with reference to the flowchart of FIG.

  The user operates the terminal device 2 to cause the terminal device 2 to start application software. Then, while looking at the menu screen or the like, the multimedia content desired by the user is designated. Then, the terminal device 2 requests the multimedia data distribution device 1 to distribute the multimedia content specified by the user by transmitting the request data RCD (# 201 in FIG. 7).

  When the multimedia data distribution apparatus 1 receives the request data RCD (# 101), the multimedia data GDT of the multimedia content indicated by the request data RCD is read by the DVD drive 10d or the hard disk 10e (# 102), and this is read. Block BL1 is generated by dividing the data into divided data BDT having a predetermined data length (# 103). The generated block BL1 is transmitted to the terminal device 2 (# 104) and stored in the transmitted data buffer 103 (# 105). If the size of the multimedia data GDT is large, the multimedia data GDT is read in order from the top, sequentially divided from the read portion, and a block BL1 is generated and transmitted.

  When the terminal device 2 receives the block BL1 (# 202), the terminal device 2 generates check data CKD for the divided data BDT included in the block BL1 (# 203), and puts it on the retransmission control data BL2 to provide a multimedia data distribution device. 1 (# 204). The received block BL1 is stored in the reception data buffer 222 (# 205).

  When the multimedia data distribution apparatus 1 receives the retransmission control data BL2 (# 106), the multimedia data distribution apparatus 1 calls the block BL1 having the same sequence number as the retransmission control data BL2, and checks the divided data BDT included in the block BL1. Data CKD ′ is generated (# 107). Then, by comparing the check data CKD included in the retransmission control data BL2 with the generated check data CKD ′, whether or not there is an error in the divided data BDT of the sequence number received by the terminal device 2 Is discriminated (# 108). That is, error detection is performed.

  If an error is detected (Yes in # 109), the divided data BDT is retransmitted to the terminal device 2 (# 110).

  If no error is detected (No in # 109), the process returns to step # 104, and the remaining divided data BDT is subjected to transmission, error detection processing, and retransmission processing as necessary (# 111). Yes). If the size of the multimedia data GDT is large, the blocking and transmission processing (# 102 to # 105) and the error detection and retransmission processing (# 106 to # 110) are executed in parallel. However, the transmission circuit 102 (see FIG. 2) transmits the divided data BDT to be retransmitted with priority over the divided data BDT to be transmitted for the first time. That is, the one with a smaller sequence number is transmitted preferentially.

  When the terminal device 2 receives the block BL1 again (# 206), the terminal device 2 stores it in the reception data buffer 222 (# 207). At this time, the older block BL1 having the same sequence number is deleted from the reception data buffer 222.

  Steps # 202 to # 205 and steps # 206 to # 208 are executed each time the block BL1 is transmitted or retransmitted from the multimedia data distribution apparatus 1.

  Then, by combining the divided data BDT of each block BL1 stored in the reception data buffer 222 in the order of the sequence number, the multimedia data GDT is regenerated, and the multimedia content is reproduced based on the multimedia data GDT ( # 208). In this way, multimedia content desired by the user is output from the display 2D and the speaker 2P.

  If the multimedia data GDT is large, a large number of divided data BDT are received one after another over a long period of time. In such a case, in parallel with the process of receiving and re-receiving the divided data BDT, the multimedia content reproduction process is executed while combining the already obtained divided data BDT. The same applies to the second embodiment.

  However, as described above, when an error is detected from the divided data BDT, the terminal device 2 must re-receive the divided data BDT. Therefore, it is desirable that the terminal device 2 determines the timing for executing the combining process in consideration of the time required from receiving new divided data BDT until re-receiving the divided data BDT. That is, when new divided data BDT is received, the combining process is not executed immediately, but is executed after waiting for a while.

  Alternatively, when no error is detected from the divided data BDT, the terminal device 2 receives the result information indicating that from the multimedia data distribution device 1, and combines the divided data BDT for which the result information is received. Processing may be executed.

  For the divided data BDT re-received in step # 206, the processing for detecting errors in steps # 203 to # 205 and steps # 106 to # 108 may be executed. When an error is detected, the divided data BDT may be transmitted again.

  According to this embodiment, data is transmitted from the multimedia data distribution device 1 to the terminal device 2 without attaching an error detection code. Instead, an error detection code is generated for the data received by the terminal device 2 and transmitted to the multimedia data distribution device 1. In this way, by using the uplink channel CHu, which has not been used so far, as the path of the error detection code, the traffic on the downlink channel CHd can be reduced more than before. In addition, error detection and data retransmission processing can be executed.

  FIG. 8 is a diagram for explaining an example of an error detection method for divided data BDT by the parity method.

  In this embodiment, all parts of the divided data BDT are retransmitted to the terminal device 2. However, when a parity code is generated as the check data CKD and CKD ′, only the part including errors in the divided data BDT is retransmitted. May be.

  For example, it is assumed that a certain 2 kilobyte divided data BDTx is transmitted from the multimedia data distribution apparatus 1 to the terminal apparatus 2. It is assumed that the terminal device 2 generates an 8-bit odd parity code as shown in FIG. 8A as the check data CKD for the received divided data BDTx. On the other hand, it is assumed that the multimedia data distribution apparatus 1 generates an 8-bit odd parity code as shown in FIG. 8B as the check data CKD ′ for the divided data BDTx.

  In such a case, the check data generation circuit 123 (see FIG. 2) of the multimedia data distribution apparatus 1 outputs the first bits, the second bits,... The eighth bits of the check data CKD and CKD ′. Compare and look for bits with different values. Then, it is determined that an error has occurred somewhere in the portion corresponding to the bit in the divided data BDTx. In the example of FIG. 8, it is determined that an error has occurred somewhere in the portion corresponding to the second and seventh bits.

  The retry transmission control circuit 104 and the block generation circuit 101 extract the data of the part (the data of the circled numbers 2 and 7 in the figure) from the divided data BDT, together with information indicating the position (address, address) of the data, Processing to transmit to the terminal device 2 is performed.

  When the terminal device 2 receives these data and information, the terminal device 2 calls the divided data BDTx stored in the reception data buffer 222. Then, the divided data BDTx is corrected by replacing the portion where the error has occurred with the received data.

  In order to increase the accuracy of error detection, the number of bits of the parity code may be increased. Alternatively, when it is desired to further improve the accuracy, the following may be performed. In the terminal device 2, the received divided data BDT is compressed by a reversible compression method and transmitted to the multimedia data distribution device 1 as check data CKD. In the multimedia data distribution apparatus 1, the check data CKD is decompressed and returned to the divided data BDT, and the divided data BDT having the same sequence number is called from the transmitted data buffer 103. Then, an error portion is detected by comparing the two. According to these methods, not only the accuracy of error detection can be improved, but also the portion where the error has occurred can be specified more precisely. Therefore, the size of data to be retransmitted to the terminal device 2 is reduced, and the traffic of the downlink channel CHd Can reduce the load. In particular, in the case of the latter method, since the error bit position can be specified, the size of data to be retransmitted becomes very small. However, in these cases, the size of the check data CKD increases, so that traffic on the uplink channel CHu increases. In addition, the load of error detection processing increases.

  The accuracy of error detection may be low, but if it is desired to reduce the uplink traffic, the number of bits of the parity code may be reduced.

  When a CRC code is used as the check data CKD, the multimedia data distribution apparatus 1 can perform error detection processing without generating the check data CKD ′. That is, the multimedia data distribution apparatus 1 performs the arithmetic processing based on the CRC method that has been conventionally executed on the reception side, the check data CKD received from the terminal apparatus 2, and the divided data stored in the transmitted data buffer 103. An error may be detected by executing using BDT.

[Second Embodiment]
FIG. 9 is a diagram illustrating an example of the hardware configuration of the multimedia data distribution apparatus 1β, and FIG. 10 is a diagram illustrating an example of the hardware configuration of the terminal apparatus 2β.

  In the first embodiment, the data error detection process is executed by the data transmission side, that is, the multimedia data distribution device. In the second embodiment, the data reception side, that is, the terminal device is executed. The multimedia data distribution device and the terminal device used in the second embodiment are referred to as “multimedia data distribution device 1β” and “terminal device 2β”, respectively.

  Hereinafter, the configuration and processing contents different from those of the first embodiment will be mainly described. Description of parts common to the first embodiment may be omitted.

  As in the case of the first embodiment, the network system NWSβ is composed of a multimedia data distribution device 1β, a terminal device 2β, and a communication line 3. As the communication line 3, a line provided with the downlink channel CHd and the uplink channel CHu is used (see FIG. 1).

  As shown in FIG. 9, the multimedia data distribution apparatus 1β includes a CPU 15a, a RAM 15b, a ROM 15c, a DVD drive 15d, a hard disk 15e, a data transmission unit 1Sβ, a data reception unit 1Rβ, and the like. As can be seen from comparison with FIG. 2, the configuration is almost the same as that of the multimedia data distribution apparatus 1 of the first embodiment, but there is a difference in the configuration of the data transmission unit and the data reception unit.

  The functions of the CPU 15a to the hard disk 15e are basically the same as the functions of the CPU 10a to the hard disk 10e of the first embodiment. However, the ROM 15c and the hard disk 15e store programs and data for executing distribution of multimedia data GDT by a characteristic method of the second embodiment described later.

  The data transmission unit 1Sβ includes a data division circuit 171, a check data generation circuit 172, a block generation circuit 173, a transmission circuit 174, a transmitted data buffer 175, a retry transmission control circuit 176, and the like. Processing for transmission to the device 2β is performed.

  The data receiving unit 1Rβ includes a receiving circuit 181, a received data buffer 182, a data comparison circuit 183, and the like.

  As shown in FIG. 10, the terminal device 2β includes a terminal device body 2Mβ, an input device 2N ′ such as a keyboard or a mouse, a display 2D ′, a speaker 2P ′, and the like. The terminal device main body 2Mβ includes a CPU 25a, a RAM 25b, a ROM 25c, a hard disk 25d, a video interface 25e, an input interface 25f, an audio interface 25g, a data transmission unit 2Sβ, a data reception unit 2Rβ, and the like. As can be seen from comparison with FIG. 3, the configuration is almost the same as that of the terminal device 2 of the first embodiment, but there is a difference in the configuration of the data transmission unit and the data reception unit.

  The functions of the CPU 25a through the audio interface 25g, the display 2D ′, the input device 2N ′, and the speaker 2P ′ are the same as the functions of the CPU 10a through the audio interface 20g, the display 2D, the input device 2N, and the speaker 2P of the first embodiment, respectively. Basically the same. However, the ROM 25c and the hard disk 25d store programs and data for executing reception of multimedia data GDT by a characteristic method of the second embodiment described later.

  The data transmission unit 2Sβ includes a control data generation circuit 271, a transmission circuit 272, a transmitted data buffer 273, and the like, and performs processing for transmitting control data to the multimedia data distribution apparatus 1.

  The data reception unit 2Rβ includes a reception circuit 281, a reception data buffer 282, an error detection circuit 283, a data combination circuit 284, a data correction circuit 285, and the like, and receives multimedia data GDT distributed from the multimedia data distribution apparatus 1. Process to receive.

  Note that some functions of the data transmission unit 1S, the data reception unit 1R, the data transmission unit 2S, or the data reception unit 2R may be realized by software by a program.

  FIG. 11 is a diagram illustrating an example of the configuration and generation method of the block BL3, FIG. 12 is a diagram illustrating an example of the configuration of the correction request data BL4, and FIG. 13 is an example of a method of detecting an error from the erroneous existence divided data BDT ′. It is a figure explaining.

  Next, processing contents of the data transmission unit 1Sβ, the data reception unit 1Rβ, the data transmission unit 2Sβ, and the data reception unit 2Rβ will be described in detail.

  In the multimedia data distribution device 1β of FIG. 9, the data dividing circuit 171 of the data transmission unit 1Sβ reads the multimedia data GDT of the multimedia content requested by the user, read from the DVD drive 15d or the hard disk 15e. As shown in (a), the data is divided into divided data BDT having a predetermined data length.

  As shown in FIG. 11B, the check data generation circuit 172 generates error detection data for each divided data BDT. As a generation method, a CRC method, a parity check method, or the like is used. That is, a CRC code is generated when the CRC method is used, and a parity code is generated when the parity check method is used. Hereinafter, the data generated by the check data generation circuit 172 is referred to as “check data CKE”.

  As shown in FIG. 11 (c), the block generation circuit 173 adds sequence numbers “1”, “2”,... To the divided data BDT divided by the data dividing circuit 171 in order from the head, for checking. The check data CKE generated by the data generation circuit 172 is attached, and the transmission destination address, that is, on the network of the request source terminal device 2β according to the communication protocol between the multimedia data distribution device 1β and the terminal device 2β. The block BL3 is generated by assigning the address, the transmission source address, that is, the address on the network of the multimedia data distribution device 1β itself, the data type, or the like.

  The transmission circuit 174 transmits the generated block BL3 to the transmission destination address, that is, the requesting terminal device 2β.

  The transmitted data buffer 175 temporarily stores the block BL3 transmitted to the terminal device 2β. When the free space of the transmitted data buffer 175 becomes insufficient, the free space is secured by deleting in order from the block BL3 with the smallest sequence number (that is, the old one). Alternatively, it may be deleted after a predetermined time has elapsed since it was stored, regardless of the available capacity. The retry transmission control circuit 176, when an error (error) is detected in the divided data BDT in the block BL3 received by the terminal device 2β, a control process for transmitting data for correcting the portion with the error I do. The contents of such control processing will be described later.

  In the terminal device 2β of FIG. 10, the receiving circuit 281 of the data receiving unit 2Rβ receives the block BL3 transmitted from the multimedia data distribution device 1β. The received block BL3 is stored in the reception data buffer 282. Of the data included in the block BL3, data that is no longer used may be deleted upon reception.

  The error detection circuit 283 extracts the divided data BDT and the check data CKE from the received block BL3, and determines whether or not an error has occurred in the divided data BDT based on the check data CKE. That is, error detection is performed. Error detection is performed by a known method.

Similar to the block combination circuit 224 of the first embodiment, the data combination circuit 284 combines the divided data BDT included in the block BL3 stored in the reception data buffer 282 in order of sequence numbers, thereby distributing multimedia data. A process of returning the multimedia data GDT divided by the apparatus 1β is performed. However, when an error is detected from the divided data BDT, correction data is transmitted from the multimedia data distribution apparatus 1β, and the error portion is corrected by the data correction circuit 285.
Therefore, when an error is detected from the divided data BDT, the combining process for the divided data BDT is executed after the error part is corrected.

  When an error is detected from the divided data BDT by the error detection circuit 283, the control data generation circuit 271 of the data transmission unit 2Sβ includes a transmission destination address, a transmission source address, Alternatively, correction request data BL4 as shown in FIG. 12 is generated by attaching a data type or the like. The divided data BDT may be compressed by a reversible compression method. Hereinafter, the divided data BDT in which an error is detected may be referred to as “erroneous divided data BDT ′”.

  The transmission circuit 272 transmits the correction request data BL4 generated by the control data generation circuit 271 to the device at the transmission destination address, that is, the multimedia data distribution device 1β. Further, when a request for reproduction of multimedia content is made by the user, the request data RCD is transmitted to the multimedia data distribution apparatus 1β as in the transmission circuit 202 of the first embodiment. In the transmitted data buffer 273, correction request data BL4 transmitted to the multimedia data distribution apparatus 1β is temporarily stored.

  In the multimedia data distribution device 1β of FIG. 9, the reception circuit 181 of the data reception unit 1Rβ receives various data transmitted from the terminal device 2β. After reception, it is determined with reference to the data type of the data whether the data is correction request data BL4 or request data RCD.

  The check data CKE included in the correction request data BL4 is used to generate data for correcting the erroneous presence divided data BDT 'received by the terminal device 2. The generation process is executed by a data comparison circuit 183 and a retry transmission control circuit 176 of the data transmission unit 1Sβ described below. Since the data comparison circuit 183 or the retry transmission control circuit 176 is busy, when the received correction request data BL4 is not immediately used, it is stored in the reception data buffer 182.

  The data comparison circuit 183 identifies the position where the error has occurred in the procedure as shown in FIG. In FIG. 13, the erroneous presence divided data BDT 'is extracted from the received correction request data BL4 or the correction request data BL4 stored in the reception data buffer 182 (# 321). When a plurality of correction request data BL4 is stored in the reception data buffer 182, one having a smaller sequence number is preferentially extracted. The block BL3 having the same sequence number as that of the correction request data BL4 is called from the transmitted data buffer 175 (# 322), and the divided data BDT is extracted from the block BL3 (# 323).

  The extracted divided data BDT and erroneous divided data BDT 'are compared with each other corresponding to the first bit, the second bit,... (# 324). As a result, if a different bit is found, it is detected as an error position. The comparison may be performed in units of 1 byte, 2 bytes, 4 bytes, or the like instead of performing the comparison in units of 1 bit.

  Returning to FIG. 9, the retry transmission control circuit 176 performs the comparison result obtained by the data comparison circuit 183, that is, the error position portion of the divided data BDT (erroneous divided data BDT ′) received by the terminal device 2. Data is called from the divided data BDT stored in the transmitted data buffer 175. The error correction data ATD is generated by associating the called data with information indicating the position (address in the divided data BDT). Then, the block generation circuit 173 and the transmission circuit 174 are controlled so that the error correction data ATD is transmitted to the terminal device 2.

  When an error is detected in bit units, if there is information indicating the position (address) of the error, the error can be corrected by bit inversion. Therefore, it is sufficient that the error correction data ATD includes such information, and there is no need to call correct data from the base divided data BDT.

  Based on the command from the retry transmission control circuit 176, the block generation circuit 173 attaches the sequence number of the divided data BDT as a basis to the error correction data ATD, and further, a transmission destination address, a transmission source address, a data type, or the like Is added to generate correction control data BL5. The transmission circuit 174 transmits the generated correction control data BL5 to the terminal device 2.

  In the terminal device 2β of FIG. 10, when the data correction circuit 285 of the data receiving unit 2Rβ receives the correction control data BL5, the block BL3 having the same sequence number as the correction control data BL5 is called from the reception data buffer 182 and the correction control is performed. Based on the error correction data ATD included in the data BL5, the error portion of the divided data BDT (errored divided data BDT ′) included in the block BL3 is corrected.

  For example, when an error is detected in bit units in the multimedia data distribution apparatus 1β, correction is performed by bit-inverting the data at the position (address) indicated by the error correction data ATD in the erroneous divided data BDT ′. Do. Alternatively, when an error is detected in byte units or other bit length units, correction is performed by replacing the error-containing divided data BDT ′ with the correct data indicated in the error correction data ATD. Do.

  FIG. 14 is a flowchart for explaining an example of the overall processing flow of the multimedia data distribution device 1β and the terminal device 2β.

  Next, the flow of processing of both apparatuses when distributing multimedia data GDT of multimedia contents desired by the user from the multimedia data distribution apparatus 1β to the terminal apparatus 2β will be described with reference to the flowchart of FIG.

  The terminal device 2β transmits the request data RCD to the multimedia data distribution device 1β, thereby requesting distribution of the multimedia data GDT of the multimedia content desired by the user (# 221 in FIG. 14).

  When the multimedia data distribution apparatus 1β receives the request data RCD (# 121), the multimedia data GDT of the multimedia content indicated in the request data RCD is read by the DVD drive 15d or the hard disk 15e, and this is read out with a predetermined data length. Is divided into the divided data BDT (# 122). Check data CKE (error detection code) for the divided data BDT is generated (# 123). Then, the block BL3 is generated based on the divided data BDT and the check data CKE (# 124), and is transmitted to the terminal device 2 (# 125), and is stored in the transmitted data buffer 175 (#). 126). When the size of the multimedia data GDT is large, the multimedia data GDT is read in order from the top, and the processes of steps # 122 to # 125 are sequentially performed from the read portion.

  When the terminal device 2β receives the block BL3 (# 222), the terminal device 2β checks whether or not there is an error in the divided data BDT based on the check data CKE included in the block BL3 (# 223). If an error is detected (Yes in # 224), the correct data is transmitted by transmitting the divided data BDT (erroneous divided data BDT ′) on the correction request data BL4 to the multimedia data distribution apparatus 1β. (# 225). Regardless of the presence or absence of an error, the block BL3 received from the multimedia data distribution apparatus 1β is stored in the reception data buffer 282 (# 226).

  When the multimedia data distribution apparatus 1β receives the correction request data BL4 (# 127), the multimedia data distribution device 1β includes the erroneous existence divided data BDT ′ included in the correction request data BL4 and the divided data BDT based on the erroneous divided data BDT ′ (that is, the same sequence number). Are identified and extracted from the erroneously divided data BDT ′ (address) where the error has occurred (# 128). Then, error correction data ATD for correcting the portion is generated, and this is put on the correction control data BL5 and transmitted to the terminal device 2β (# 129).

  When the terminal device 2β receives the error correction data ATD (# 227), the terminal device 2β corrects the divided data BDT (erroneous divided data BDT ′) based on this (# 228). The corrected divided data BDT is stored again in the reception data buffer 282 as necessary (# 229). Note that the error correction data ATD is not transmitted for the divided data BDT for which no error has been detected, so the processing of steps # 227 to # 229 is skipped.

  Then, the divided data BDT stored in the reception data buffer 282 is combined in the order of the sequence number to regenerate the multimedia data GDT, and the multimedia content is reproduced based on the multimedia data GDT (# 230).

  According to the second embodiment, not all data in which an error is detected is retransmitted as in the prior art, but only the portion including the error or only the error position (address) information is transmitted. Therefore, it is possible to reduce the traffic on the downlink channel CHd as compared with the conventional case.

  FIG. 15 is a diagram for explaining a modification of the configuration and generation method of the correction request data BL4 '.

  In the second embodiment, when an error is detected from the divided data BDT received by the terminal device 2β, the entire portion of the divided data BDT (error existence divided data BDT ′) is transmitted to the multimedia data distribution device 1β. However, only a part may be transmitted.

  For example, as shown in FIG. 15A, check data CKE, which is an 8-bit odd parity code, is received together with the divided data BDT (erroneous divided data BDT ′), and 8 bits from the erroneous divided data BDT ′. It is assumed that the check data CKE ′, which is an odd parity code, is calculated.

  Here, when the corresponding bits of the check data CKE and CKE ′ are compared with each other, the second bit does not match, so the portion corresponding to the second bit of the erroneous presence divided data BDT ′, that is, the portion of the circled number 2 It can be seen that an error has occurred somewhere. Hereinafter, this portion of data is referred to as “error portion data ABD”.

  Therefore, the terminal device 2β generates the correction request data BL4 ′ as shown in FIG. 15 (b), and instead of transmitting the entire part of the erroneous existence divided data BDT ′, the error part data ABD and its position (address) are displayed. Send.

  Receiving the correction request data BL4 ', the multimedia data distribution apparatus 1β compares only the error partial data ABD included therein with the original divided data BDT, and specifies the position where the error has occurred.

  As a result, it is possible to reduce traffic on both the uplink channel CHu and the downlink channel CHd, and to reduce the load of error position identification processing in the multimedia data distribution apparatus 1β.

  In the first and second embodiments, multimedia data GDT is divided into a plurality of divided data BDTs for transmission / reception, but transmission / reception may be performed without division.

  The functions of the multimedia data distribution apparatuses 1 and 1β may be applied to a streaming server on the Internet. In this case, error detection may be performed in units of packets.

  In addition, the entire network system NWS, multimedia data distribution apparatus 1, terminal apparatus 2, communication line 3 or the configuration of each part, processing contents, processing order, database contents, and the like are appropriately changed in accordance with the spirit of the present invention. Can do.

The following additional notes are disclosed with respect to the embodiment described above.
(Appendix 1) Having a first device and a second device,
The first device includes
Data transmission means for transmitting data to the second device;
An error presence / absence determining means for determining whether an error has occurred in the data received by the second device;
The second device includes
Data receiving means for receiving the data from the first device;
Error detection code generation means for generating an error detection code of the data received from the first device;
An error detection code transmitting means for transmitting the generated error detection code to the first device, and
The error presence / absence determining means determines whether or not an error has occurred in the data received by the second device based on the error detection code transmitted from the second device,
The data transmission means retransmits the data to the second device when it is determined that an error has occurred in the data received by the second device.
A data transmission / reception system characterized by the above.
(Supplementary Note 2) Second error detection code generation means for generating, as the second error detection code, a parity code having a predetermined bit length of the data transmitted to the second device, in the first device. Is provided,
The error detection code generation means generates a parity code of the predetermined bit length of the data received from the first device as the error detection code,
Whether the error has occurred in the data received by the second device by comparing the values of corresponding bits of the error detection code and the second error detection code. And determine the portion of the data that contains an error,
The data transmission means retransmits only the portion determined to contain an error in the data received by the second device;
The data transmission / reception system according to attachment 1.
(Additional remark 3) It has a 1st apparatus and a 2nd apparatus,
The first device includes
Error detection code generation means for generating an error detection code of target data that is target data to be transmitted to the second device;
Target data transmission means for transmitting the target data to the second device together with the error detection code;
An error part determining means for determining an error part that is an error part from the target data received by the second device;
Correction data transmission means for transmitting correction data for correcting the error portion determined by the error determination means to the second device, and
The second device includes
Target data receiving means for receiving the target data together with the error detection code from the first device;
An error presence / absence determining means for determining whether an error has occurred in the received target data based on the error detection code received together with the target data;
When it is determined that an error has occurred in the received target data, a check data transmission unit is provided that transmits the target data to the first device as check data,
The error part determination means transmits the error part of the target data received by the second device from the target data and the second device transmitted by the target data transmission means to the second device. Discriminate by comparing with the check data
A data transmission / reception system characterized by the above.
(Supplementary Note 4) The second device is provided with data correction means for correcting the error portion of the received target data based on the correction data transmitted from the first device. ing,
The data transmission / reception system according to attachment 3.
(Appendix 5) The communication line connecting the first device and the second device is a full-duplex communication line.
The data transmission / reception system according to any one of appendix 1 to appendix 4.
(Appendix 6) A multimedia data distribution device that distributes multimedia data, and a playback device that reproduces multimedia content based on the multimedia data,
In the multimedia data distribution apparatus,
Multimedia data transmitting means for transmitting the multimedia data to the playback device;
An error presence / absence determining means for determining whether or not an error has occurred in the multimedia data received by the playback device;
The playback device includes
Multimedia data receiving means for receiving the multimedia data from the multimedia data distribution device;
Error detection code generation means for generating an error detection code of the multimedia data received from the multimedia data distribution device;
An error detection code transmission means for transmitting the generated error detection code to the multimedia data distribution device,
The error presence / absence determining means determines whether an error has occurred in the multimedia data received by the playback device based on the error detection code transmitted from the playback device,
The multimedia data transmitting means retransmits the multimedia data to the playback device when it is determined that an error has occurred in the multimedia data received by the playback device;
A multimedia data transmission / reception system.
(Supplementary note 7) a multimedia data distribution device that distributes multimedia data; and a playback device that reproduces multimedia content based on the multimedia data;
In the multimedia data distribution apparatus,
Error detection code generation means for generating an error detection code of distribution target data that is multimedia data to be distributed;
Distribution target data transmitting means for transmitting the distribution target data together with the error detection code to the reproduction device;
An error part determination means for determining an error part in which an error has occurred from the distribution target data received by the playback device;
Correction data transmission means for transmitting correction data for correcting the error part determined by the error determination means to the playback device, and
The playback device includes
Distribution target data receiving means for receiving the distribution target data together with the error detection code from the multimedia data distribution apparatus;
An error presence / absence determining means for determining whether an error has occurred in the received distribution target data based on the error detection code received together with the distribution target data;
When it is determined that an error has occurred in the received distribution target data, a check data transmission unit is provided that transmits the distribution target data to the multimedia data distribution apparatus as check data.
The error part determining means is configured to transmit the error part of the distribution target data received by the reproduction apparatus from the reproduction apparatus and the distribution target data transmitted to the reproduction apparatus by the distribution target data transmission means. It is determined by comparing with the check data.
A multimedia data transmission / reception system.
(Appendix 8) Send data to the other device,
Receiving the error detection code of the data received by the counterpart device from the counterpart device;
Based on the received error detection code, determine whether an error has occurred in the data received by the counterpart device,
If it is determined that an error has occurred in the data, the data is retransmitted to the counterpart device.
A data transmission method characterized by the above.
(Supplementary note 9) A data transmission method for transmitting data from a first device to a second device,
The first device transmits the data to the second device;
The second device generates an error detection code of the data received from the first device;
The second device transmits the generated error detection code to the first device;
The first device determines whether an error has occurred in the data received by the second device based on the error detection code transmitted from the second device,
When it is determined that an error has occurred in the data received by the second device, the first device retransmits the data to the second device;
A data transmission method characterized by the above.
(Supplementary Note 10) A data transmission method for transmitting data from a first device to a second device,
The first device generates an error detection code of target data that is target data to be transmitted,
The first device transmits the target data together with the error detection code to the second device;
The second device determines whether an error has occurred in the target data received from the first device based on the error detection code received together with the target data,
When it is determined that an error has occurred in the received target data, the second device transmits the target data to the first device as check data,
The first device transmits the error part, which is the part in which the error is generated in the target data received by the second device, to the second device and the target data and the second data. It is determined by comparing with the check data transmitted from the device,
The first device transmits correction data for correcting the error part to the second device.
A data transmission method characterized by the above.

  In the case where the channel (downstream channel) from the data provider side device to the recipient side device is more frequently used than the upstream channel, as in the case of distributing multimedia content data, the present invention It is preferably used to reduce channel traffic and prevent delays in data transmission.

It is a figure which shows the example of the whole structure of the network system which concerns on this invention. It is a figure which shows the example of the hardware constitutions of a multimedia data delivery apparatus. It is a figure which shows the example of the hardware constitutions of a terminal device. It is a figure explaining the example of the structure of a block, and the production | generation method. It is a figure explaining the example of a structure and the production | generation method of retransmission control data. It is a figure explaining the example of the detection method of the error of division | segmentation data. It is a flowchart explaining the example of the flow of the whole process of a multimedia data delivery apparatus and a terminal device. It is a figure explaining the example of the error detection method of the division data by a parity system. It is a figure which shows the example of the hardware constitutions of a multimedia data delivery apparatus. It is a figure which shows the example of the hardware constitutions of a terminal device. It is a figure explaining the example of the structure of a block, and the production | generation method. It is a figure which shows the example of a structure of correction request data. It is a figure explaining the example of the method of detecting an error from erroneous existence division data. It is a flowchart explaining the example of the flow of the whole process of a multimedia data delivery apparatus and a terminal device. It is a figure explaining the modification of a structure and the production | generation method of correction request data.

Explanation of symbols

NWS, NWSβ network system (data transmission / reception system)
1, 1β Multimedia data distribution device (first device)
102 Transmission circuit (data transmission means)
123 Check data generation circuit (second error detection code generation means)
124 data comparison circuit for checking (error presence determination means)
172 Check data generation circuit (error detection code generation means)
174 Transmission circuit (object data transmission means, correction data transmission means)
176 Retry transmission control circuit (correction data transmission means)
183 Data comparison circuit (error part discrimination means)
2, 2β terminal device (second device)
202 Transmission circuit (error detection code transmission means)
221 receiving circuit (data receiving means)
223 Check data generation circuit (error detection code generation means)
272 Transmission circuit (data transmission means for checking)
281 Receiving circuit (object data receiving means)
283 Error detection circuit (error presence determination means)
ATD error correction data (correction data)
BDT division data (data, target data)
CKD check data (error detection code)
CKD 'check data (second error detection code)
CKE check data (error detection code)
GDT multimedia data (data, target data)

Claims (5)

A first device and a second device;
The first device includes
Data transmission means for transmitting data to the second device;
An error presence / absence determining means for determining whether an error has occurred in the data received by the second device;
The second device includes
Data receiving means for receiving the data from the first device;
Error detection code generation means for generating an error detection code of the data received from the first device;
An error detection code transmitting means for transmitting the generated error detection code to the first device, and
The error presence / absence determining means determines whether or not an error has occurred in the data received by the second device based on the error detection code transmitted from the second device,
The data transmission means retransmits the data to the second device when it is determined that an error has occurred in the data received by the second device.
A data transmission / reception system characterized by the above. The first device is provided with second error detection code generation means for generating a parity code having a predetermined bit length of the data transmitted to the second device as a second error detection code. ,
The error detection code generation means generates a parity code of the predetermined bit length of the data received from the first device as the error detection code,
Whether the error has occurred in the data received by the second device by comparing the values of corresponding bits of the error detection code and the second error detection code. And determine the portion of the data that contains an error,
The data transmission means retransmits only the portion determined to contain an error in the data received by the second device;
The data transmission / reception system according to claim 1. A first device and a second device;
The first device includes
Error detection code generation means for generating an error detection code of target data that is target data to be transmitted to the second device;
Target data transmission means for transmitting the target data to the second device together with the error detection code;
An error part determining means for determining an error part that is an error part from the target data received by the second device;
Correction data transmission means for transmitting correction data for correcting the error portion determined by the error determination means to the second device, and
The second device includes
Target data receiving means for receiving the target data together with the error detection code from the first device;
An error presence / absence determining means for determining whether an error has occurred in the received target data based on the error detection code received together with the target data;
When it is determined that an error has occurred in the received target data, a check data transmission unit is provided that transmits the target data to the first device as check data,
The error part determination means transmits the error part of the target data received by the second device from the target data and the second device transmitted by the target data transmission means to the second device. Discriminate by comparing with the check data
A data transmission / reception system characterized by the above. Send data to the other device,
Receiving the error detection code of the data received by the counterpart device from the counterpart device;
Based on the received error detection code, determine whether an error has occurred in the data received by the counterpart device,
If it is determined that an error has occurred in the data, the data is retransmitted to the counterpart device.
A data transmission method characterized by the above. A data transmission method for transmitting data from a first device to a second device,
The first device generates an error detection code of target data that is target data to be transmitted,
The first device transmits the target data together with the error detection code to the second device;
The second device determines whether an error has occurred in the target data received from the first device, based on the error detection code received together with the target data,
When it is determined that an error has occurred in the received target data, the second device transmits the target data to the first device as check data,
The first device transmits the error part, which is an error part in the target data received by the second device, to the second device and the second data. It is determined by comparing with the check data transmitted from the device,
The first device transmits correction data for correcting the error part to the second device.
A data transmission method characterized by the above.