JP2004140861A - Communication system, transmitting device, receiving device, and communication system provided with these devices - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To be able to effectively transmit data from a transmitting station to a receiving station without waste of band, and to retransmit the data so that request of two or more receiving stations are satisfied. <P>SOLUTION: Data packets P(1) to P(8) sent from a route station 1 (transmitting station) are received by two or more leaf stations A to C (receiving stations). The data packets P(1) to P(8) include data blocks B (101), etc. which respectively contain an error correcting code. The data packets P(1) to P(8) include retransmission request rights for speaking L(201), L(202) to L(801), L(802) which give the retransmission request tights for speaking to 2 stations out of leaf stations A to C in a communication cycle. The leaf stations A to C request retransmission of a data block, which is not possible to correct errors in the communication cycle given the retransmission request rights for speaking to the route station 1 by transmitting retransmission packet LA(1), LB(1), LC(1), etc. The route station 1 transmits data packets including the requested data block in the next or subsequent communication cycle. <P>COPYRIGHT: (C)2004,JPO

Description

The present invention relates to a data communication method and a data communication system for retransmitting data to a plurality of receiving devices, and further relates to a transmitting device and a receiving device provided in such a data communication system.

Generally, there are two error recovery methods: ARQ (Automatic Retransmission Request) and FEC (Forward Error Correction). The ARQ detects errors on the receiving station side based on the redundant code added on the transmitting station side, and if an error is detected, sends a request for retransmission of the packet to the transmitting station and retransmits on the transmitting station side. It is a method of performing. FEC is a method in which the receiving station performs error correction based on the redundant code added by the transmitting station.

Also, for example, in A Two-Step Adaptive Error Recovery Scheme for Video Transmission over Wireless Networks: Daji Qiao and Kang G. Shin, IEEE INFOCOM 2000, a hybrid ARQ scheme combining the ARQ scheme and the FEC scheme is proposed. In this method, a transmitting station adds a block error correction code (RS code), and a receiving station performs error correction based on the information. The receiving station transmits a positive ACK or a negative ACK to the transmitting station according to the result of the error correction. The transmitting station receives a negative ACK, or retransmits the packet if no ACK is received during the timeout interval.

It is difficult to achieve an almost error-free state without retransmission under an environment with a bad bit error rate even if an error correction code having a high correction capability is used. For this reason, it is generally necessary to add processing such as concatenating codes between convolutional codes and block codes, and interleaving, and thus there is a problem that the circuit scale is increased and a huge number of buffers are required for the transmitting station and the receiving station.

Further, according to the above-mentioned document, when the error cannot be corrected in the error correction processing at the receiving station, when the receiving station transmits a retransmission request to the transmitting station, the transmitting station retransmits data in packet units to the request. Is described. In this method, the packet length is very long (800 to 900 bytes), and a large amount of bandwidth is required for one retransmission. In particular, when the communication environment is poor, it is necessary to perform retransmission many times, but the longer the packet length, the less the number of retransmissions. Therefore, data transmitted in real time, such as moving images and audio, may not be able to complete transmission within a prescribed time, which may cause inconvenience that the moving image or audio reproduced at the receiving station may be disrupted or interrupted. There is. This becomes more significant as the communication speed is lower.

Furthermore, when there are a plurality of receiving stations for one transmitting station, the transmitting station must grasp the reception status of all the receiving stations. Moreover, if retransmission requests from a plurality of receiving stations are made at the same time, the transmitted retransmission request packets may interfere with each other and the retransmission request may not be transmitted to the transmitting station. For this reason, it is required that the retransmission request of each receiving station be transmitted individually without interference.

The present invention has been made in order to solve the above-described problems, and can efficiently transmit data from a transmitting station to a receiving station without wasting bandwidth, and to a plurality of receiving stations. It is another object of the present invention to provide a communication system, a transmitting device, a receiving device, and a communication system that can retransmit data so as to satisfy the requests of all receiving stations.

In order to solve the above problem, the communication system according to the present invention divides data into one or more blocks, and uses a data packet including a data block having an error correction code for each block to perform one transmission. A communication method in which the same data packet transmitted from a station is received by a plurality of receiving stations, wherein the receiving station having an uncorrectable data block is assigned a retransmission request for the data block for each receiving station. While transmitting to the transmitting station during a retransmission request permission period, the transmitting station retransmits a data block requested by each receiving station.

In addition, in order to solve the above-mentioned problem, the transmitting apparatus of the present invention divides data into one or more blocks and transmits a data packet including a data block having an error correction code for each block to a plurality of receiving apparatuses. When receiving a retransmission request for a data block transmitted by the receiving apparatus having an uncorrectable data block, the data block is retransmitted.

In the above configuration, the transmitting station (transmitting device) transmits a data packet including one or more data blocks to the receiving station (receiving device). Perform error correction. Then, when there is a data block for which error correction is not possible, the receiving station transmits a retransmission request for requesting the transmitting station to retransmit the data block in a retransmission request permission period assigned to each receiving station in advance. Upon receiving the retransmission request, the transmitting station retransmits a data block corresponding to the request.

By retransmitting data in data block units, it is not necessary to retransmit the entire data packet, and data can be transmitted efficiently without wasting bandwidth. Further, even if there are a plurality of receiving stations, the receiving station transmits a retransmission request in a retransmission request permission period given in advance, so that retransmission requests from all receiving stations can be transmitted without collision.

In addition, a certain receiving station requests retransmission, and another receiving station simultaneously receives a data block retransmitted from the transmitting station. In this case, when the receiving station receives a data block that has not been requested to be retransmitted again, the receiving station discards the data block or returns the same data block received to a storage area that already stores the data block. Can be overwritten.

The transmission device may include a retransmission request designation unit that designates, among the plurality of reception devices, a reception device permitted to perform a retransmission request to the transmission device based on permission information provided in the data packet. preferable.

As described above, since the receiving apparatus is designated by the retransmission request designating means on the basis of the permission information provided in the data packet, only the designated receiving apparatus can transmit the retransmission request. . Further, since the receiving device specifies the permission of the retransmission request by receiving the data packet, there is no need to separately perform communication for specifying the receiving device to which the retransmission request is permitted.

It is preferable that the transmission device includes a retransmission period specifying unit that specifies the retransmission request permission period based on time information provided in the data packet.

(4) Since the retransmission request permission period is designated based on the permission information by the retransmission period designation means, the receiving apparatus is assigned the retransmission request permission period only by receiving the data packet.

The transmission device includes a frequency channel specification unit that specifies a frequency channel to be used for transmission of a retransmission request in the retransmission request permission period based on frequency channel information provided in a data packet from the transmission device. Is preferred.

If the transmitting device and the receiving device communicate on different frequency channels, preparing a plurality of frequency channels for transmitting the retransmission request from the receiving device can simultaneously transmit the retransmission requests from the plurality of receiving devices at different reception times. A retransmission request from the station can be transmitted. For this reason, it is possible to request retransmission more efficiently than in a case where retransmission requests are transmitted from a plurality of receiving apparatuses on the same frequency channel.

(4) In such an environment, the frequency channel used in the transmission of the retransmission request is specified by the frequency channel specifying means, so that the frequency channel used by each receiving station can be appropriately allocated. Further, since the receiving device receives the data packet and the frequency channel is allocated, there is no need to separately perform communication for frequency channel allocation.

The transmission device, when there are a plurality of retransmission requests from the reception device, a priority that permits a retransmission request to a reception device that has performed a retransmission request of a data block transmitted in the past in preference to other reception devices. It is preferable to have permission means.

(4) When the data transmitted from the transmitting device is real-time data such as a moving image or a sound, the receiving device needs to receive the data by a specified time to reproduce the moving image or the sound without being interrupted or disturbed. Therefore, when the transmitting apparatus receives a retransmission request for a plurality of data blocks from the receiving apparatus, the remaining time until the data block transmitted for the first time in the past is reproduced is shorter.

Therefore, the transmission of data can be stabilized by giving priority to the retransmission request to the receiving device that has made such a retransmission request of the data block over other receiving devices by the priority permission unit.

The transmission device includes a rank determining unit that determines a rank of retransmitting the data block earlier than a retransmission request for a data block transmitted in the past when there are a plurality of retransmission requests from the reception device. Is preferred.

Also in this configuration, by determining the retransmission order such that the data block is retransmitted first from the retransmission request for the older data block as described above, the older data block is given priority. Retransmission is performed, and data transmission can be stabilized.

The transmitting apparatus includes a multiple rank determining unit that determines the order of retransmission first from a data block for which a retransmission request is received from a greater number of receiving apparatuses when there are a plurality of retransmission requests from the receiving apparatus. Is preferred.

When the transmitting apparatus receives retransmission requests from a plurality of receiving apparatuses, the order determining means determines the order so that the data blocks requested to be retransmitted from a larger number of receiving apparatuses are retransmitted first from the data blocks. , The data block with the highest retransmission request is transmitted first in the data packet. Therefore, when a phenomenon occurs in which a data block provided at the end of a data packet cannot be transmitted, a data block with a large number of retransmission requests can be reliably retransmitted.

When the transmission device receives a retransmission request from a specific receiving device a predetermined number of times or more within a predetermined period, the transmitting device may include a priority retransmission permission unit that preferentially permits the retransmission request to the receiving device. preferable.

場合 When a retransmission request from a specific receiving device is issued every time or frequently, it is considered that the receiving environment of the receiving device is worse than other receiving devices. In this case, by preferentially permitting the retransmission request to the receiving device that has received the retransmission request more than a predetermined number of times by the priority retransmission permitting unit, the reception status of the receiving device can be made closer to another receiving device. .

According to another aspect of the present invention, there is provided a receiving apparatus, comprising: a data packet transmitted from a transmitting apparatus, the data being divided into one or more blocks and including a data block having an error correction code for each block; Receiving a data block for which error correction is not possible, despite having transmitted a retransmission request for the data block to the transmitting device a predetermined number of times or more, the transmission according to the retransmission request. A non-reception confirmation unit for confirming that the data block from the device has not been received within a specified time; and a non-reception of the data block is confirmed by the non-reception confirmation unit. And retransmission request limiting means for limiting.

デ ー タ In some cases, a data block may not be retransmitted after a certain period of time even though a retransmission request has been transmitted from a receiving device to a transmitting device several times. In this case, it is considered that the retransmission request from the transmitting device does not easily reach the transmitting device due to the deterioration of the communication condition or the like.

Therefore, when the receiving apparatus receives the same data packet transmitted from the transmitting apparatus and there is a data block for which error correction cannot be performed, it is necessary to retransmit the data block to the transmitting apparatus a predetermined number of times or more. Nevertheless, if a retransmission request is not received within a specified time in consideration of a retransmission delay time or a failure to the number of retransmission requests of another receiving device, that fact is confirmed by the non-reception confirmation unit. Then, the retransmission request restricting means restricts the retransmission request of the data block.

As described above, the retransmission request for the data block is limited, so that even if the receiving device cannot receive the data block even if the retransmission request is repeatedly transmitted, the retransmission request cannot be transmitted within the specified time required for transmitting the moving image or audio real-time data. It is possible to avoid retransmission of a data block that is too late. Further, by repeating such a wasteful retransmission request, it is possible to prevent the retransmission request from another receiving device from being restricted.

The above-mentioned receiving apparatus, comprising: an error correction unit that performs error correction of the data block based on the error correction code; and a correction unit that specifies a data block in which error correction can be performed by the error correction unit based on a result of the error correction. Possible block specifying means, uncorrectable block specifying means for specifying a data block that is not error-correctable based on the data block specified to be error-correctable by the correctable block specifying means, and the uncorrectable block It is preferable that the information processing apparatus further includes a retransmission request transmitting unit that transmits a retransmission request for the data block that has been determined to be uncorrectable by the specifying unit to the transmitting device.

In the above configuration, when the receiving device receives the data packet, the error correcting means corrects the error of the data block in the data packet. The data block for which error correction is possible is specified by the correctable block specifying means based on the result of the error correction. Then, the uncorrectable data block is specified by the uncorrectable block specifying means based on the correctable data block specified as described above. Then, a retransmission request for a data block whose error cannot be corrected is transmitted by the retransmission request transmitting unit.

Conversely, if an attempt is made to directly specify a data block for which error correction cannot be performed, the data block is specified based on the data block that could not be corrected by the error correction means, but the information of the data block itself may be incorrect. Therefore, there is a possibility that a data block for which error correction cannot be performed cannot be specified. Therefore, by specifying a data block that can be error-corrected and specifying a data block that cannot be corrected based on the result, a data block to be retransmitted can be correctly specified.

通信 シ ス テ ム The communication system according to the present invention is characterized by including any one of the transmitting devices and a plurality of any of the receiving devices. In the communication system configured as described above, a data block can be efficiently retransmitted even when a plurality of receiving apparatuses receive a data packet transmitted by the transmitting apparatus.

As described above, according to the communication method of the present invention, data is divided into one or more blocks and transmitted from one transmission station using a data packet including a data block having an error correction code for each block. The same data packet is received by a plurality of receiving stations, and the receiving station having an uncorrectable data block sends a retransmission request for the data block to the transmitting station during a retransmission request permission period assigned to each receiving station. While transmitting, the transmitting station retransmits a data block requested by each receiving station.

In addition, the transmitting apparatus of the present invention divides data into one or more blocks, transmits a data packet including a data block having an error correction code for each block to a plurality of receiving apparatuses, When a retransmission request for the data block transmitted by the receiving apparatus having a block is received, the data block is retransmitted.

By retransmitting data in data block units, it is not necessary to retransmit the entire data packet, and data can be transmitted efficiently without wasting bandwidth. Further, even if there are a plurality of receiving stations, the receiving station transmits a retransmission request in a retransmission request permission period given in advance, so that retransmission requests from all receiving stations can be transmitted without collision. Therefore, there is an effect that the same data packet can be efficiently transmitted with high reliability within a limited delay time so as to satisfy the requirements of a plurality of receiving stations.

The transmission device includes a retransmission request designation unit that designates, among the plurality of reception devices, a reception device to which a retransmission request to the transmission device is permitted, based on permission information provided in the data packet. Since the receiving device specifies the permission of the retransmission request by receiving the data packet, there is no need to separately perform communication for specifying the receiving device to which the retransmission request is permitted. Therefore, there is an effect that the retransmission request permission period can be appropriately assigned.

The transmission device includes retransmission period designation means for designating the retransmission request permission period based on time information provided in the data packet, so that the reception device receives the retransmission request permission period only by receiving the data packet. A period is assigned. Therefore, there is an effect that the retransmission request permission period can be appropriately assigned.

The transmission device includes a frequency channel specification unit that specifies a frequency channel to be used for transmission of a retransmission request in the retransmission request permission period based on frequency channel information provided in a data packet from the transmission device. Accordingly, when a plurality of frequency channels for transmitting the retransmission request from the receiving device are possible, the frequency channel used for transmitting the retransmission request is specified by the frequency channel specifying unit, so that the frequency used by each receiving station is Channels can be allocated appropriately. Further, since the receiving device receives the data packet and the frequency channel is allocated, there is no need to separately perform communication for frequency channel allocation. Therefore, when a retransmission request is transmitted using a different frequency channel, the retransmission request permission period can be appropriately allocated.

The transmission device, when there are a plurality of retransmission requests from the reception device, a priority that permits a retransmission request to a reception device that has performed a retransmission request of a data block transmitted in the past in preference to other reception devices. The provision of the permission means makes it possible to stabilize data transmission even when a data block transmitted for the first time in the past, such as moving image data or audio data, has less time remaining until it is reproduced. . Therefore, it is possible to transmit the real-time data without deteriorating the quality.

The transmission device includes a rank determining unit that determines a rank of retransmitting the data block earlier than a retransmission request for a data block transmitted in the past when there are a plurality of retransmission requests from the reception device. Thereby, a data block in the past is retransmitted preferentially, and data transmission can be stabilized. Therefore, it is possible to transmit the real-time data without deteriorating the quality.

The transmitting apparatus includes a multiple rank determining unit that determines the order of retransmission first from a data block for which a retransmission request is received from a greater number of receiving apparatuses when there are a plurality of retransmission requests from the receiving apparatus. As a result, the data block frequently requested to be retransmitted is transmitted first in the data packet. Therefore, when a phenomenon occurs in which a data block provided at the end of a data packet cannot be transmitted, a data block with a large number of retransmission requests can be reliably retransmitted. Therefore, there is an effect that the average value of the probability that the data block is not correctly transmitted to the receiving device within the predetermined time for all the receiving devices can be minimized.

When the transmitting apparatus receives a retransmission request from a specific receiving apparatus more than a predetermined number of times within a certain period of time, the transmitting apparatus includes a priority retransmission permission unit that preferentially permits the retransmission request to the receiving apparatus. In addition, it is possible to make the receiving status of a receiving device that has received a retransmission request more than a predetermined number of times, which is considered to be bad in receiving status, close to other receiving devices. Therefore, there is an effect that the reception state of the specific receiving device can be easily improved.

The receiving apparatus of the present invention is a receiving apparatus that receives a data packet transmitted from a transmitting apparatus, the data being divided into one or more blocks, and including a data block having an error correction code for each block. When there is a data block for which error correction cannot be performed, a data block from the transmitting device in response to the retransmission request is transmitted within a specified time, even though a retransmission request for the data block has been transmitted to the transmitting device a predetermined number of times or more. Non-reception confirmation means for confirming that the data block has not been received, and retransmission request restriction means for restricting a retransmission request for the data block when the non-reception of the data block is confirmed by the non-reception confirmation means. Configuration.

As a result, when it is confirmed that a data block for which error correction cannot be performed has not been received, a retransmission request for the data block is restricted. In addition, it is possible to avoid retransmission of a data block that cannot be completed within a specified time required for transmitting real-time data of a moving image or audio. Further, by repeating such a wasteful retransmission request, it is possible to prevent the retransmission request from another receiving device from being restricted. Therefore, in the case where the receiving device is used in a configuration in which a plurality of receiving devices transmit a retransmission request to the transmitting device, there is an effect that the retransmission request from the receiving device can be appropriately allocated.

The above-mentioned receiving apparatus, comprising: an error correction unit that performs error correction of the data block based on the error correction code; and a correction unit that specifies a data block in which error correction can be performed by the error correction unit based on a result of the error correction. Possible block specifying means, uncorrectable block specifying means for specifying a data block that is not error-correctable based on the data block specified to be error-correctable by the correctable block specifying means, and the uncorrectable block Retransmission request transmission means for transmitting a retransmission request for a data block identified as being uncorrectable by the identification means to the transmission device, thereby enabling error correction based on the error-correctable data block. Unable data blocks are identified, so correctly identify the data blocks to be retransmitted Door can be. Therefore, there is an effect that a data block to be requested for retransmission can be accurately determined.

Since the communication system of the present invention is configured to include any one of the transmitting devices and any one of the plurality of receiving devices, even in a situation where a plurality of receiving devices receive a data packet transmitted by the transmitting device. Thus, the data block can be efficiently retransmitted. Therefore, there is an effect that data can be transmitted efficiently so as to satisfy the requirements of a plurality of receiving stations.

The following is a description of an embodiment of the present invention, with reference to FIGS. 1 to 15.

The communication system according to the present embodiment includes a root station 1 and a plurality of leaf stations 2 as shown in FIG. Communication between the root station 1 and the leaf stations 2... Is performed by radio (radio waves, infrared rays, etc.). The root station 1 transmits data input in real time, such as a moving image or audio from a video camera or a television, to the leaf stations 2 as data packets composed of a plurality of data blocks. Each data block (for example, B (101) to B (104) in FIG. 1) includes data subjected to error correction coding processing.

As shown in FIG. 3, the root station 1 as a transmitting device includes a data storage device 11, an error correction encoding processing unit 12, a data transmitting unit 13, a retransmission request packet receiving unit 14, a retransmission request packet analyzing unit 15, and a retransmission request A possible leaf station allocation processing unit (hereinafter simply referred to as an allocation processing unit) 16 is provided.

The data storage device 11 includes a memory and its peripheral circuits (memory control circuit and the like), and temporarily stores new input data from a video camera or the like. The data storage device 11 outputs new input data in a state of being divided into predetermined blocks so that an error correction coding processing unit 22 described later performs coding processing for each data block. Further, the data storage device 11 reads out a desired data block from the memory based on the retransmission request information obtained by the analysis of the retransmission request packet analysis unit 15 in order to output the data of the data block that has been requested to be retransmitted. Control circuit.

The error correction encoding processing unit 12 performs an error correction encoding process by adding an error correction code such as a Hamming code or a Reed-Solomon code to the block data from the data storage device 11. The data transmission unit 13 creates a data packet by adding a header to each block of data from the error correction encoding processing unit 12, and transmits the data packet to the transmission device 1. Therefore, the data transmission unit 13 includes a data transmission circuit and an interface circuit for outputting data, and transmits a data packet to the leaf stations 2. Further, the data transmission unit 13 adds, to the data packet, the allocation information of the retransmission request floor, described later, generated by the allocation processing unit 16.

The retransmission request packet receiving unit 14 includes a data receiving circuit and an interface circuit for inputting data in order to receive a retransmission request packet transmitted from a retransmission request packet transmitting unit 27 described later.

Each time the retransmission request packet transmitter 27 receives the retransmission request packet, the retransmission request packet analyzer 15 determines which leaf station 2 the retransmission request packet is from based on the header (physical layer header H described later). The analysis is performed based on the data block number in the retransmission request packet of the data block that could not be received. For example, the retransmission request packet analysis unit 15 previously assigns a bit for each data block to indicate the number of the data block to be subjected to the retransmission request with reference to the header. Is compared with the number set as described above, and the bit of the number corresponding to both is set to "1". As described above, the retransmission request packet analysis unit 15 can be configured by a logic circuit. The analysis result indicating to which data block the retransmission request has been issued is supplied to the data storage device 11 and the allocation processing unit 16.

The allocation processing unit 16 generates allocation information of the retransmission request floor, which is the right for the leaf station 2 to transmit the retransmission request (determines the retransmission request permission period), based on the above analysis result. Specifically, the allocation processing unit 16 generates the retransmission request floor in the order of the priorities assigned to the leaf stations 2 (for example, the order of the leaf stations A to C in FIG. 1), but within a certain period of time. To the leaf station 2 which has a large number of retransmission requests, the retransmission request floor is preferentially given ignoring the order (priority retransmission permission means).

For this reason, the allocation processing unit 16 stores the leaf station 2 to which the retransmission request floor has been given last time, and re-calculates from the information of the leaf station 2 requesting retransmission obtained by the retransmission request packet analysis unit 15. When it is confirmed that the same leaf station 2 is requesting retransmission, the right to give retransmission request is given to the leaf station 2 as described above. The number of retransmission requests serving as a criterion for preferentially giving the right to give a retransmission request is not limited to two times, but may be three or more predetermined times. Further, when the retransmission request from any of the leaf stations 2 is no longer transmitted, the allocation processing unit 16 returns the order of occurrence of the retransmission request floor from the transmission of the next data packet to the original (order of the leaf station 2). .

The retransmission request floor is determined by information of a physical layer header H (see FIG. 5) of the data packet, which will be described later, and only the designated leaf station 2 is designated by the root station 1 (retransmission request permission period). Has time information for requesting retransmission. The assignment processing unit 16 gives such a retransmission request floor to the leaf station 2 and specifies the leaf station 2 to which the retransmission request is permitted, and thus has a function as a retransmission request specifying unit and a retransmission period specifying unit. In addition, when a plurality of frequency channels used by the leaf station 2 in the retransmission request are prepared as described later, the allocation processing unit 16 determines, based on the frequency channel information provided in the physical layer header H, Since it is specified whether or not the retransmission request floor is assigned to the frequency channel, it has a function as frequency channel specifying means.

The allocation processing unit 16 gives a retransmission request voice so that a retransmission request to the leaf station 2 that has issued a retransmission request of a data block transmitted in the past has a higher priority than a retransmission request of another leaf station 2 (priority permitting means). . Also, when there are a plurality of retransmission requests from the leaf stations 22 and the like, the allocation processing unit 16 determines the order of retransmission of data blocks transmitted earlier in the order of retransmission requests for the data blocks (order determining means). . Furthermore, when there are a plurality of retransmission requests from the leaf station 2, the allocation processing unit 16 determines the order of retransmission first from the data blocks for which retransmission requests from a larger number of leaf stations 2 have been issued (multiple order determination means). ).

As shown in FIG. 4, the leaf station 2 as a receiving device includes a data receiving unit 21, an error correction decoding processing unit 22, a data storage device 23, a received data analysis unit 24, a received block information storage device 25, a retransmission request packet generation And a retransmission request packet transmitting unit 27.

The data receiving unit 21 includes a data receiving circuit and an interface circuit for inputting data. The error correction decoding processing unit 22 as error correction means uses an error correction coding data block in a data packet received by the data receiving unit 21 as an error correction code and performs error correction decoding processing based on a predetermined method. To restore the data.

The data storage device 23 includes a memory and its peripheral circuits (such as a memory control circuit), and temporarily stores output data to be output. The data storage device 23 restores a data packet by arranging the data blocks decoded by the error correction decoding processing section 22 in the arrangement order, and outputs the data packet at a predetermined timing. The data storage unit 23 waits for the data block that has failed to be received because the error correction decoding processing unit 22 cannot decode the data block to be retransmitted from the root station 1 as described later, and waits for the reception to be successful. The data packet is restored together with the data block that has been set.

The received data analysis unit 24 as a correctable block specifying unit analyzes and determines (specifies) a data block that can be correctly received (error correctable) for each data block based on the processing result of the error correction decoding processing unit 22. I do. Specifically, it is determined which data block has been correctly corrected (received) based on the content of the data on which the error correction was correctly performed by the error correction decoding processing unit 22 (tag information T (see FIG. 5) described later). The determination result is given by the data block number.

The received block information storage device 25 as a correctable block specifying unit recognizes (specifies) a data block that cannot be received (error cannot be corrected) based on the data block determined to be correctly received by the received data analysis unit 24. ). For this reason, the reception block information storage device 25 has a circuit for searching for a data block in which a data block of a missing number has failed to receive by referring to the number given to each data block. As a result, a data block to be retransmitted is recognized. Further, the reception block information storage device 25 has a register for storing the recognized data block.

Further, the received block information storage device 25 stores the data block of the data block requested to be retransmitted from the root station 1 within the specified time even though the retransmission request packet has been transmitted from the retransmission request packet After confirming that the data block is not received, and confirming that, the output of the information of the data block to the retransmission request packet generator 26 is limited (reduction in output frequency or stop of output). As described above, the reception block information storage device 25 also has functions as non-reception confirmation means and retransmission request restriction means.

The retransmission request packet generation unit 26 generates a retransmission request packet for requesting retransmission of the data block, including the information of the data block that failed to be received and stored in the reception block information storage device 25. For this reason, the retransmission request packet generator 26 generates a reproduction request packet by adding a header or the like to the data block for which retransmission is requested.

The retransmission request packet transmitting unit 27 as a retransmission request transmitting unit is a part including a data receiving circuit and an interface circuit for inputting data, and transmits the retransmission request packet to the root station 1. The retransmission request packet transmitting unit 27 transmits the retransmission request packet in a communication cycle in which transmission of the retransmission request packet is permitted based on the retransmission request floor given by the root station 1.

In the leaf station 2, the received data analysis unit 24 analyzes the data block that has been correctly corrected, and recognizes the data block that cannot be corrected in the received block information storage device 25 based on the result. . Conversely, even if the data is given to the received data analysis unit 24 in order to directly determine the data block for which error correction could not be performed, there is a possibility that the information itself that the data itself was not correctly corrected is incorrect. Therefore, there is a possibility that the reception data analysis unit 24 cannot correctly analyze. For this reason, the data block to be retransmitted can be correctly determined by the above-described analysis based on the correctly corrected data block.

Here, the formats of the data packet transmitted from the root station 1 and the retransmission request packet transmitted from the leaf station 2 will be described.

As shown in FIG. 5, the transmission data packet is composed of a physical layer preamble P, a physical layer header H, and data D. The data D is composed of n data blocks B1 to Bn (error correction blocks). Each of the data blocks B1 to Bn has a data body B to which tag information T and an error correction code EC are added.

The tag information T includes retransmission order definition information of each of the data blocks B1 to Bn and an identifier indicating the retransmission data block. The retransmission order definition information may be, for example, a sequence string for each block information or a combination of a packet number and a block number. In this example, the tag information T is included in each of the data blocks B1 to Bn. However, such a configuration is not always necessary. For example, the tag information T of all the data blocks B1 to Bn is added to the head of the data D. May be added together.

One data packet is transmitted in units of 188 bytes when a moving image is transmitted by MPEG, for example. Therefore, the data packet transmitted from the root station 1 has a length of 188 bytes + α including a retransmission margin described later.

As shown in FIG. 6, the retransmission request packet is composed of a physical layer preamble P, a physical layer header H, and data D, as in the case of the transmission data packet. The data D includes retransmission request number information N, n pieces of transmission order definition information R1 to Rn, and an error detection code ED. The root station 1 determines the retransmission order of the data blocks B1 to Bn based on the transmission order definition information R1 to Rn.

In this retransmission request packet format, the data D includes an error detection code ED so that the root station 1 can detect an error. However, as shown in FIG. It may include an error correction code.

In the communication system configured as described above, in the leaf station 2, when a data packet from the root station 1 is received by the data receiving unit 21, the data packet is sent to the error correction decoding processing unit 22 for each data block. The data is subjected to error correction processing and stored in the data storage device 23. Information on whether or not each data block has been correctly received is obtained as a result of analysis of each data block by the received data analysis unit 24 based on the result of error correction by the error correction decoding processing unit 22. The information is stored in the reception block information storage device 25 and is used by the retransmission request packet generator 26 as needed. Then, at the time when the retransmission request is permitted by the retransmission request floor given by the root station 1, the retransmission request packet is transmitted from the retransmission request packet transmitting unit 27 to the root station 1.

Upon receiving the retransmission request packet, the root station 1 transmits a transmission data packet including a retransmission data block corresponding to the retransmission request, as described later. At the leaf station 2, when the retransmission data block is correctly received, it is stored in the data storage device 23. Then, the retransmitted data blocks are arranged in order together with the already stored data blocks and output as received data.

When the leaf station 2 receives a retransmission data block transmitted from the root station 1 in response to a retransmission request from another leaf station 2, the data is double-input to the data storage device 23. However, since the data is already stored in the data storage device 23, the retransmitted data block may be discarded or overwritten and stored again.

The retransmission request floor of the leaf station 2 is determined by the information of the header portion of the data packet transmitted by the root station 1 as described above, and only the designated leaf station 2 has the time specified by the root station 1. You can request retransmission. Even when the retransmission request is unnecessary, the designated leaf station 2 transmits information indicating no retransmission request to the root station 1.

ル ー ト In some cases, it is difficult for the root station 1 to receive the retransmission request packet from the leaf station 2 due to the deterioration of the communication environment. In such a case, in the leaf station 2, if the received block information storage device 25 confirms that the requested data block has not been received even though the retransmission request packet has been transmitted a predetermined number of times or more, the data for the retransmission request is transmitted. The information of the block is not output to the retransmission request packet generator 26, or the number of times of output is limited. As a result, a retransmission request packet for the data block is not generated, or the generation frequency of the retransmission request packet is reduced. Thereafter, no retransmission request is made, or the number of retransmission requests decreases.

In this way, when a data block cannot be received even if the leaf station 2 repeatedly requests retransmission, it is possible to avoid retransmission of a data block that is not in time within a prescribed time required for transmitting moving image or audio real-time data. it can. Also, by repeating such useless retransmission requests, it is possible to prevent the retransmission requests from other leaf stations 2 from being restricted.

On the other hand, in the root station 1, new input data is stored in the data storage device 11 as data to be transmitted. The retransmission request is received by the retransmission request packet receiving unit 14, and the retransmission request packet analyzing unit 15 analyzes a data block that requires retransmission. Information on the retransmission request obtained by the retransmission request packet analyzing unit 15 is transmitted to the data storage device 11. The retransmission data information is included in the next transmission data packet and is read from the data storage device 11. Subsequently, the new input data information is read from the data storage device 11. An error correction code is added to the data information by the error correction encoding processing unit 12 for each data block. In this way, a data packet that can be error-corrected in data block units is generated.

The assignment processing unit 16 generates information (assignment information) of the leaf station 2 for giving a retransmission request floor to the leaf station 2 that has requested retransmission. The data packet from the error correction coding processing unit 12 is transmitted to the leaf station 1 with the above allocation information added by the data transmission unit 13.

The above allocation information is generated by the allocation processing unit 16 and added to the data packet by the data transmission unit 13. However, in order to efficiently perform the leaf station allocation, the retransmission request packet analysis unit 15 sends the retransmission data of each leaf station 2 The request status may be fed back.

Next, the operation of the above communication system will be described with reference to the flowchart of FIG.

First, the root station 1 generates a transmission data packet according to the transmission order (S1), and transmits this to the leaf stations 2 (S2). On the other hand, the leaf stations 2 which have the right to speak the retransmission request determine whether or not the transmission data packet has been correctly received (S3), and if they have been correctly received, return an acknowledgment ACK to the root station 1. As a result, the process returns to S1, and the root station 1 generates the next transmission data packet.

On the other hand, in S3, when a certain leaf station 2 does not correctly receive a transmission data packet, a retransmission request packet is transmitted from the leaf station 2 to the root station 1. Upon receiving the retransmission request packet, the root station 1 determines a retransmission order for each leaf station 1 and generates a data packet based on the order (S4). Then, the root station 1 transmits the generated retransmission data packet in S2 of the next communication cycle.

As described above, in the communication system of the present embodiment, by retransmitting data in data block units, it is not necessary to retransmit the entire data packet, and data can be transmitted efficiently without wasting bandwidth. Can be. Even if there are a plurality of leaf stations 2, the leaf station 2 transmits a retransmission request for a period determined by the retransmission request floor given in advance, so that the retransmission requests from all the leaf stations 2 do not collide. Can be sent. Therefore, even when the communication speed is low, it is possible to secure a sufficient time for transmitting data such as moving images and audio in real time. The details will be more clear in the embodiments described below.

Next, specific examples of data retransmission in the above communication system will be described in the following embodiments.

Assuming that the number of all leaf stations 2 is n, the number of leaf stations 2 transmitting retransmission request packets in one communication cycle (hereinafter simply referred to as a cycle) is 1 to n, and the bandwidth and transmission of data Determined by the data length. In the first to fourth embodiments, an example will be described in which two leaf stations 2 can request retransmission every transmission cycle of a data packet. In the fifth embodiment, an example will be described in which one leaf station 2 can request retransmission for each data packet transmission cycle. The initial setting is that all the leaf stations 2 can make retransmission requests equally so that the root station 1 will be given the retransmission request right from the next cycle on to the leaf station 2 to which no retransmission request floor has been given in that cycle. .

Further, as the leaf station 2, three leaf stations A to C (see FIG. 1) are provided for one root station 1, and data transmission from the root station 1 to the leaf stations A to C is performed. I have. The number b of blocks of the transmission data is four. Since one retransmission block is guaranteed, five blocks are secured as a transmission band. When a data block is retransmitted, the root station 1 transmits a data packet with the number of blocks increased to 5 (= b + 1), and transmits the data packet while maintaining the increased number of blocks until there is no delay due to the retransmission.

When transmitting a moving image, if the number of blocks is large, the band of the moving image that can be transmitted by one data packet is widened, so that the image can be transmitted with high quality. However, since the number of retransmissions of the data block is reduced due to the wide band, the image is likely to be interrupted or disturbed. On the other hand, when the number of blocks is large, the transmission band of a moving image that can be transmitted by one data packet is narrow, so that the image transmission quality is reduced. However, since the number of retransmissions of the data block is increased, the image is interrupted or disturbed. It becomes difficult. Therefore, the number of blocks is determined by which of the image quality and the number of retransmissions of the data block is more important.

In each of the embodiments, the codes A, B and C are used when referring to a specific leaf station, and the code 2 is used when no leaf station is specified.

(Example 1)
In the present embodiment, as shown in FIGS. 1 and 9, the data packet P (1) transmitted by the root station 1 includes data blocks B (101) to B (104) provided in error correction units, It has the requested floor information L (101) and L (102). In the data packet P (1) of the root station 1, the retransmission request of the leaf station A is specified by the retransmission request floor information L (101), and the retransmission request of the leaf station B is specified by the retransmission request floor information L (102). Is specified. In this state, after transmitting the data packet from the root station 1, the leaf station A transmits a retransmission request packet LA (1) corresponding to the retransmission request floor information L (101), and the leaf station B transmits the retransmission request packet. The retransmission request packet LB (1) is transmitted corresponding to the right information L (102).

Since the leaf station A performed error correction on the data packet P (1) from the root station 1, all data blocks B (101) to B (104) in the data packet could be normally received. Sends an acknowledgment ACK indicating that there is no retransmission request to the root station 1. On the other hand, since the leaf station B could not correct the error for the data block B (104), the retransmission request information R (104) for requesting the retransmission of the data block B (104) in the retransmission request packet LB (1). ).

In the second cycle, the root station 1 retransmits the data block B (104) for which the retransmission request was received in the previous cycle with the data packet P (2), and subsequently transmits new data blocks B (201) to Send B (204). In this cycle, the leaf station C is given the retransmission request floor by the retransmission request floor information L (201), and the leaf station A is given the retransmission request floor by the retransmission request floor information L (202). Here, as a result of the leaf station C receiving the data packet P (2) and performing error correction, the data block B (101) when the data packet P (1) is received, although the data block P (1) is normally received, is received. Because the data could not be received normally, retransmission request information R (101) requesting retransmission of data block B (101) is transmitted in retransmission request packet LC (1). On the other hand, since the leaf station A has transmitted the acknowledgment ACK in the retransmission request packet, it does not request retransmission.

In the third cycle, the root station 1 similarly retransmits the data block B (101) for which the retransmission request was received in the previous cycle with the data packet P (3), and subsequently transmits a new data block B ( 301) to B (304) are transmitted. In this cycle, the leaf station B is given the retransmission request floor by the retransmission request floor information L (301), and the leaf station C is given the retransmission request floor by the retransmission request floor information L (302). Here, as a result of receiving the data packet P (3) and performing error correction, the leaf station C successfully receives the data packet P (3), but the data block B (304) when the data packet P (3) is received is Since the data could not be received normally, retransmission request information R (304) requesting retransmission of data block B (304) is transmitted in retransmission request packet LC (3). On the other hand, since the leaf station B has transmitted the acknowledgment ACK in the retransmission request packet, it does not request retransmission.

In the present embodiment, there are three leaf stations A to C, and two leaf stations 2 that can request retransmission are designated per cycle. Therefore, all the leaf stations A to C can evenly transmit the retransmission request twice. This can be represented by a timing chart as shown in FIG. Thus, the retransmission request packets of all the leaf stations A to C are transmitted evenly in a fixed order. Here, it is assumed that such an even transmission state of the retransmission request packet is the basic assignment of the retransmission request floor of the leaf station.

When estimating the reception status of each of the leaf stations A to C from the retransmission request status of the first to third stages shown in FIG. 1, the leaf station C transmits the retransmission request every time, and the reception status is the lowest. You can judge that it is a bad situation. For this reason, the root station 1 receives the retransmission request by giving priority to the leaf station C with the retransmission request voice right after this determination. Therefore, the leaf station C is continuously given the retransmission request floor in the fourth and subsequent cycles, and can preferentially make the retransmission request until the fifth cycle in which the retransmission requests do not continue.

Until the retransmission request packet LC (4), that is, the transmission of the acknowledgment ACK, since the leaf station C has transmitted the retransmission request every time, the root station 1 has given the leaf station C the floor for the retransmission request every time. Subsequently, in the transmission of the retransmission request packet LC (5), the state has changed to a state in which there is no retransmission request, so that the root station 1 thereafter gives each leaf station 2 a uniform retransmission request voice. In other words, when there are a plurality of retransmission requests from a certain leaf station 2, priority is given to retransmission of older data, and the retransmission request voice of that leaf station 2 is raised. Equalize the resend request floor.

FIG. 9 shows an example in which leaf station C requests retransmission more than twice (predetermined number) as described above, so that retransmission can be preferentially requested. FIG. 10 shows all leaf stations. An example is shown in which A to C are equally given the retransmission request floor. In this embodiment, all transmissions are performed on the same radio channel, and the talk time of each station is specified by the root station 1 so that the transmission packets of the root station 1 and the leaf stations A to C do not collide with each other. Has gone.

9 and 10, data packets P (1) to P (6), retransmission request packets LA (1) to LA (4) from leaf station A, and retransmission request packet LB (1 ) To LB (4) and retransmission request packets LC (1) to LC (4) from the leaf station C correspond to the respective packets in FIG. Also, the hatched blocks of the data packets P (1) to P (6) correspond to the retransmission request floor information L (101) to L (602) for designating the leaf station 2 having the retransmission request right. Equivalent to. 1, 9 and 10, the illustration of the physical layer preamble P and the physical layer header H provided at the head of each data packet is omitted.

(Example 2)
In this embodiment, as shown in FIG. 11, the leaf station B receives all data blocks B (101) to B (104) of the data packet P (1) from the root station 1 due to radio wave interference in wireless communication. 4) shows an example of retransmission when the reception of ()) fails.

In the first cycle, the leaf station B is given the retransmission request floor by the retransmission request floor information L (102) of the data packet P (1), but fails to receive the data packet P (1). The retransmission request packet LB (1) cannot be transmitted. On the other hand, since the root station 1 did not receive the retransmission request packet LB (1) from the leaf station B, the root station 1 continuously gives a retransmission request voice to the leaf station B even in the next cycle.

On the other hand, since the leaf station B has correctly received the data packet P (2) in this cycle, the information of the data packet P (2) is analyzed by the above-described reception data analysis unit 24, and If there is information missing from the packet analysis information, it can be determined that the previous packet reception has failed. The leaf station B refers to this information and requests retransmission of all data blocks B (101) to B (104) that have not been received so far by transmitting a retransmission request packet LB (2). The root station 1 receives R (101-104) of the retransmission request packet LB (2) and retransmits the data blocks B (101) to B (104) in the next data packet P (3).

Thereafter, as the communication situation between the root station 1 and the REIT station B improves, if the subsequent data packets continue to be normally received, the transmission of the data packet P (7) will result in four data blocks B (701) The data is transmitted at 〜B (704) and the delay due to retransmission is eliminated.

(Example 3)
In the present embodiment, as shown in FIG. 12, leaf stations A and B receive data packets from root station 1 and transmit retransmission request packets LA (n) and LB (n). Has failed to receive the retransmission request packet transmitted by the leaf station B. When the root station 1 fails to receive a retransmission request packet from a certain leaf station 2, the above-mentioned assignment processing unit 16 continuously allocates a retransmission request floor to the leaf station 2 by the above-mentioned allocation processing unit 16.

More specifically, in the figure, the retransmission request packets LB (1), LB (2), and LB (5) indicated by the broken line of the leaf station B are transmitted, but the root station 1 cannot receive them. It represents that. The root station 1 requests the re-transmission of the data block B (104) of the data packet P (1) by the leaf station B, but fails to receive the retransmission request packet LB (1). Are assigned the right to resend request. On the other hand, the leaf station B requests retransmission of the data block B (104) that could not be received in the previous cycle and the data block B (204) that could not be received in the current cycle.

(4) On the other hand, since the root station 1 has failed to receive the retransmission request packet LB (2) from the leaf station B again, the root station 1 assigns the retransmission request floor to the leaf station B again. In the third stage cycle, when the root station 1 succeeds in receiving the retransmission request packet LB (2) from the leaf station B, in the fourth stage cycle of the data packet P (1), Data blocks B (104) and B (204) are retransmitted.

In this embodiment, the root station 1 assigns a retransmission request floor to the leaf station 2 until the root station 1 succeeds in receiving the retransmission request packet of the leaf station 2 at least and becomes able to retransmit the data block to the leaf station 2. Like that. Therefore, when the communication environment between the root station 1 and the leaf station 2 is in a bad state (such as the presence of an obstacle or an excessive separation between the two stations), the root station 1 transmits a retransmission request packet from the leaf station 2. When the root station 1 can receive the retransmission request packet due to the improvement of the communication environment, the root station 1 can retransmit the requested data block to the leaf station 2 even if the reception fails.

(Example 4)
In this embodiment, as shown in FIG. 13, there is shown an example in which there are a plurality of retransmission requests from each leaf station, and retransmission is performed in ascending order of data blocks with a large number of retransmission requests.

In the first cycle, leaf station A requests retransmission of data blocks B (101) and B (103) by retransmission request information R (101, 103), and leaf station B transmits retransmission request information R (103). Requesting retransmission of data block B (103). Here, since there are a plurality of retransmission requests for the data block B (103), the root station 1 assigns the data block B (103) to the same data packet P (1) more than the data block B (101) for which the retransmission request is small. Retransmitted first.

In the second cycle, the leaf station C requests retransmission of the data blocks B (104) and B (203) by the retransmission request information R (104, 203), and subsequently, the leaf station A transmits the retransmission request information R ( 201) requests retransmission of data block B (201). The data block B (104) requested to be retransmitted from the leaf station C is included in the data packet P (1) in the previous cycle, and the requested data blocks B (104), B (201), B ( 203) is transmitted first. Therefore, in the third cycle, the root station 1 gives priority to the data packet P (3) over the retransmission of the data blocks B (201), B (203), and B (204) of the data packet P (2). The data block B (104) is retransmitted.

After that, if the communication conditions improve and the subsequent data packets P (4) to P (7) continue to be normally received, the delay due to retransmission is eliminated in the transmission of the data packet P (7) as shown in FIG.

で は In this embodiment, data blocks with more retransmission requests are preferentially retransmitted. This makes it possible to more reliably retransmit a data block whose retransmission request is high, when a phenomenon occurs in which some subsequent data blocks cannot be received due to some failure.

In the present embodiment, the leaf stations A to C all make retransmission requests on the same radio wave (frequency) channel. However, a radio channel that the root station 1 transmits to the leaf stations A to C is provided separately. If a plurality of radio channels are prepared as transmission channels for retransmission requests of the leaf stations A to C, retransmission requests can be made more efficiently.

(Example 5)
This embodiment is different from the above-described first to fourth embodiments in that, as shown in FIGS. 14 and 15, one of the leaf stations A to C is sequentially given a retransmission request floor one by one. .

In FIG. 14, a data block in which error correction has become impossible when a data packet is received by the leaf station 2 is indicated by a cross. The leaf station A receives the third data block B (103) of the data packet P (1), the second data block B (202) of the data packet P (3), and the data packets P (5) and P (6), respectively. ) Cannot correct errors in the third data blocks B (502) and B (602). In addition, the leaf station B detects errors in the second and third data blocks B (102) and B (103) of the data packet P (1) and the third data block B (502) of the data packet P (5). Correction is not possible. Further, the leaf station C cannot correct the error of the second data block B (201) of the data packet P (2) and the first data block B (102) of the data packet P (3).

The root station 1 specifies the leaf station A in the data packet P (1) using the retransmission request floor information L (101) and transmits the data blocks B (101) to B (104). On the other hand, since the leaf station A has the right to request retransmission in this cycle, it transmits a retransmission request packet LA (1) requesting retransmission of the data block B (103). Then, in the next cycle, the root station 1 retransmits the data block B (103) with the data packet P (2) based on the information of the received retransmission request packet LA (1), and newly transmits the data block B ( 201) to B (204) are being transmitted.

{Circle around (4)} In the data packet P (2), the root station 1 specifies the leaf station B by the retransmission request floor information L (201). For this reason, since the leaf station B has the right to resend the retransmission request in this cycle, it requests the retransmission of the data block B (102) and, at the same time, the data block B for which the error correction was not possible in the data packet P (2). The retransmission of (202) is requested by transmitting a retransmission request packet LB (1). Here, the leaf station B cannot correct the error of the data block B (103) in the data packet P (1), but has successfully received the data block P (2). ) Does not require retransmission.

Then, in the next cycle, the root station 1 retransmits the data blocks B (102) and B (202) in the data packet P (3) based on the information of the retransmission request packet LB (1), and newly transmits data. Blocks B (301) to B (303) are transmitted. Further, the root station 1 assigns a retransmission request floor to the leaf station C based on the retransmission request floor information L (301). Although the data block B (304) should be sent in this cycle, it is not sent in this cycle but is sent in the next cycle due to retransmission of the data blocks B (102) and B (202). You.

As shown in FIG. 14, in this cycle, the leaf station A cannot correct the error of the data block B (202), and the leaf station C cannot correct the error of the data block B (102). Since the leaf station C has the right to request retransmission in this cycle, it requests the retransmission of the data block B (201) by transmitting the retransmission request packet LC (1).

From the next cycle onward, similarly, the root station 1 retransmits the data block according to the information of the retransmission request from the leaf stations A to C, and the leaf stations A to C change the retransmission request as needed according to the error correction state. Send Then, if the subsequent data packets continue to be received normally, in the transmission of the data packet P (7), the data is transmitted in the four data blocks B (701) to B (704), and the delay due to retransmission is eliminated.

The present invention is applicable to a data communication method and a data communication system for retransmitting data to a plurality of receiving devices, and further to a transmitting device and a receiving device provided in such a data communication system.

FIG. 3 is an explanatory diagram illustrating a frame configuration of each packet of Example 1 transmitted and received between a root station and a plurality of leaf stations in the communication system according to the embodiment of the present invention. FIG. 2 is a block diagram illustrating a configuration of the communication system. FIG. 3 is a block diagram illustrating a configuration of the root station. FIG. 3 is a block diagram illustrating a configuration of the leaf station. FIG. 3 is an explanatory diagram showing a format of a data packet transmitted from the root station. FIG. 4 is an explanatory diagram showing a format of a retransmission request packet transmitted from the leaf station. FIG. 9 is an explanatory diagram showing a format of another retransmission request packet transmitted from the leaf station. It is a flowchart which shows the operation procedure of the said communication system. It is a timing chart which shows the transmission / reception timing when a specific leaf station gives priority to give a retransmission request between a root station and a plurality of leaf stations in the communication system. It is a timing chart which shows the transmission / reception timing when each leaf station is equally given the retransmission request floor between the root station and a plurality of leaf stations in the communication system. FIG. 9 is an explanatory diagram showing a frame configuration of a data packet of a second embodiment transmitted and received between a root station and a plurality of leaf stations in the communication system. FIG. 14 is an explanatory diagram showing a frame configuration of each packet of the third embodiment transmitted and received between a root station and a plurality of leaf stations in the communication system. FIG. 13 is an explanatory diagram showing a frame configuration of each packet of a fourth embodiment transmitted and received between a root station and a plurality of leaf stations in the communication system. 16 is a timing chart showing transmission and reception timings in a fifth embodiment in which packets are transmitted and received between a root station and a plurality of leaf stations in the communication system. FIG. 14 is an explanatory diagram illustrating a frame configuration of each packet according to the fifth embodiment.

Explanation of reference numerals

1 root station (transmitting station, transmitting device)
2 leaf station (receiving station, receiving device)
14 Retransmission requestable leaf station allocation processing (retransmission request specifying means, retransmission period specifying means
Step, frequency channel designating means, priority permitting means, rank determining means, majority ranking
Setting means, priority retransmission permission means)
15 Retransmission request packet analysis unit 22 Error correction decoding processing unit (error correction means)
24 Received data analyzer (correctable block specifying means)
25 Received block information storage device (uncorrectable block specifying means,
Stage, retransmission request limiting means)
26 retransmission request packet generator 27 retransmission request packet transmitter (retransmission request transmitter)
AC leaf station (receiving station, receiving device)
B1 to Bn data block (error correction block)
P (1) to P (8) Data packet

Claims (12)

Data is divided into one or more blocks, and the same data packet transmitted from one transmitting station is received by a plurality of receiving stations using a data packet including a data block having an error correction code for each block. Communication method,
While the receiving station having an uncorrectable data block transmits a retransmission request for the data block to the transmitting station during a retransmission request permission period assigned to each receiving station,
The communication system, wherein the transmitting station retransmits a data block requested by each receiving station. A transmission device, wherein data is divided into one or more blocks, and a data packet including a data block having an error correction code for each block is transmitted to a plurality of reception devices,
A transmitting apparatus for transmitting a data block retransmitted upon reception of a data block retransmission request transmitted by the receiving apparatus having an uncorrectable data block during a retransmission request permission period allocated to each receiving apparatus; . A retransmission request designating unit for designating, among the plurality of receiving devices, a receiving device to which a retransmission request to the transmitting device is permitted based on permission information provided in a data packet from the transmitting device. The transmitting device according to claim 2, wherein 4. The transmission apparatus according to claim 2, further comprising a retransmission period designating unit that designates the retransmission request permission period based on time information provided in the data packet. A frequency channel that specifies a frequency channel to be used in a retransmission request by a receiving device permitted to retransmit to the transmitting device among a plurality of receiving devices based on frequency channel information provided in a data packet from the transmitting device. 5. The transmitting device according to claim 2, further comprising a designation unit. When there are a plurality of retransmission requests from the receiving device, a priority permitting means is provided for allowing a retransmission request to a receiving device that has issued a retransmission request for a data block transmitted in the past with priority over other receiving devices. The transmitting device according to claim 2, wherein: When there are a plurality of retransmission requests from the receiving apparatus, the apparatus further comprises rank determining means for determining the order of retransmitting the data block earlier than the retransmission request for the data block transmitted in the past. Item 7. The transmission device according to item 2 or 6. When there are a plurality of retransmission requests from the receiving device, a plurality of rank determining means for determining the order of retransmission first from the data blocks for which retransmission has been requested from a larger number of receiving devices are provided. Item 8. The transmitting device according to item 2, 6 or 7. 3. A system according to claim 2, further comprising a priority retransmission permitting means for preferentially permitting the retransmission request to the retransmission request when a retransmission request from a specific receiving device is received a predetermined number of times or more within a predetermined period. , 6, 7 or 8. A receiving device that receives a data packet transmitted from a transmitting device, the data being divided into one or more blocks, and including a data block having an error correction code for each block,
When there is an uncorrectable data block, the data block from the transmitting device in response to the retransmission request is transmitted within a specified time, even though the retransmitting request for the data block has been transmitted to the transmitting device a predetermined number of times or more. A non-reception confirmation means for confirming that no reception was received,
A receiving apparatus comprising: a retransmission request restricting unit for restricting a retransmission request of the data block when the non-reception of the data block is confirmed by the non-reception confirming unit. Error correction means for performing error correction of the data block based on the error correction code,
Correctable block specifying means for specifying a data block capable of error correction by the error correcting means based on the result of error correction,
Uncorrectable block specifying means for specifying a data block that is not error-correctable, based on the data block specified to be error-correctable by the correctable block specifying means,
11. The reception apparatus according to claim 10, further comprising: a retransmission request transmitting unit that transmits a retransmission request of a data block identified as being uncorrectable by the uncorrectable block identifying unit to the transmitting device. apparatus. A communication system comprising: the transmission device according to any one of claims 2 to 9; and the plurality of reception devices according to claim 10 or 11.

Images