JPH07123079A - Data transmission equipment - Google Patents

Abstract

(57) [Summary] [Purpose] A system that has a long loopback delay time, uses a relatively simple protocol, maintains throughput, and
The purpose is to reduce the size and power consumption of the terminal. [Structure] Consecutive M blocks are continuously transmitted as one group by one transmission, the receiving side sequentially performs error detection on the M blocks, and sends back an acknowledgment ACK or a retransmission request response NAK. If an error is detected in the i-th block, the M-th block after the i-th block is discarded, and the retransmission request response NAK for the i-th block is returned to the transmitting side. On the transmission side that receives the retransmission request response NAK, M + i-1 starting with the i-th block
The M blocks up to the th are continuously transmitted. On the receiving side, error detection is performed sequentially as in the first case,
An acknowledgment ACK or a resend request response NAK is sent back.
Such processing is continued until all blocks are correctly received.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a data transmission device used for digital data communication and the like, and more particularly to a data transmission device having a high throughput and a simplified algorithm.

[0002]

2. Description of the Related Art In systems requiring high reliability such as digital data communication, error control by the ARQ (automatic repeat request) method has been widely used. AR
The Q method can be classified into the following three basic methods depending on the retransmission procedure.

(1) Stop-And-Wait (S
AW) ARQ method When a signal block is transmitted, the transmission side waits for a reply from the reception side, and if ACK (acknowledgement, here is an acknowledgment), transmits the next block, and NAK (negative acknowledgment, here resend). If it is a request response), the same block is retransmitted.

(2) Go-Back-N (GBN) A
RQ method Blocks are continuously transmitted during the return delay time (RTD), and when ACK or NAK is returned,
Determine whether to send the next block or retransmit the previous consecutive block. Here, N represents the number of blocks that can be transmitted during RTD. This system is very efficient when the condition of the communication path is good and the RTD is short, but is extremely poor when the condition of the communication path is bad and the RTD is long.

(3) Selective-Repea
t (SR) ARQ method Blocks are continuously transmitted even during the return delay time (RTD), and only the block for which NAK is returned is retransmitted. Therefore, it has a buffer to store the correct block received after the erroneous block, and when the retransmitted signal becomes an ACK, the user is in the order sent with the block recorded in the buffer. Output. This method is the most efficient method among these three methods, but the logic becomes complicated and a huge capacity buffer is required on the receiving side.

Regarding the ARQ system, for example, IEEE
COMMUNICATIONS MAGAZINE Vol. 22, No. 12, S.M. Lin, D.L. J. Coste
Ilo, Jr. , M .; J. Miller's paper "Au"
tomatic-Repeat-Request Er
Ror-Control Schemes ”.

Generally, in mobile communication, since the radio waves are subject to multipath fading which is received via multiple paths, the error rate varies greatly. When high-speed digital data is transmitted on such a communication path, blocks with a large number of errors are continuously received for a long period, or blocks without errors are continuously received for a long period. Up to, there are a very wide range of errors in the received block. Therefore, it is desired that the ARQ method to be applied efficiently operates according to the state of the communication path at that time. Several such methods have been devised and announced as such methods. As one of them, Type II hybrid AR
There is Q method. The Type II hybrid ARQ system is
This is a method that combines the ARQ method with an error correction method. At first, only the parity bit for error detection is added to the information bit and transmitted, and when NAK is returned, the parity bit for error correction is retransmitted. . This retransmitted parity bit is constructed so that the information bit can be extracted from it, and if no error is detected, the information bit is recovered from it, and if an error is detected, the information bit stored in the buffer is recovered. Error correction is performed together with.

R. A. Comroe, D.M. J. Cost
ello et al. use a block code as an error correction code and an ARQ-based Selective-Repeat (S) as a transmission procedure.
It is proposed to apply the Type II hybrid ARQ method using the R) mode to a mobile communication system. (For example, IEEE JOURNAL ON SELECTE
D AREAS IN COMMUNICATIONS
No. SAC-2, Vol. A. Comroe,
D. J. Costello's paper “ARQ Sche
mes for Data Transmission
in Mobile Radio Systems ”
See).

FIG. 1 shows a transmission procedure and a processing procedure in this case.
4 and FIGS. 15 (a) to 15 (g). 15 (a)-
In (g), 11 to 14 indicate processing, and 20 and 21 indicate judgment.

FIG. 14 shows a block transmission procedure based on the SR mode. In FIG. 14, blocks 1 to 3 and 5 cannot detect an error in the first transmission, so blocks 1 to 3
As it is, the block 5 is, as shown in FIG.
It is output to the user after the processing of block 4. At the same time, an ACK for these is returned from the receiving side to the transmitting side. Since an error was detected in blocks 4 and 6, these blocks are once stored in the buffer (see FIG. 15 (a), FIG.
It shows in (d). At the same time, NAKs for these are returned from the receiving side to the transmitting side. The transmitting side which has received the NAK transmits the retransmission blocks 4'and 6'of the blocks 4 and 6 in the second transmission.

Here, each of the retransmission blocks 4'and 6'includes a parity bit of an error correction code having the blocks 4 and 6 transmitted the first time as information bits. These reproduction blocks are shown in FIG. 15 (c), FIG. 15 (e), and FIG.
It is processed by the procedure shown in (f). In the retransmitted block 6'in which no error is detected, the original information bit (block 6) is restored by the parity inverter, and the block 6 stored in the buffer in the first transmission is discarded.
On the other hand, the retransmission block 4'in which an error is detected is subjected to error correction together with the block 4 stored in the buffer in the first transmission. As a result of the above processing, if there is still an error, the block stored in the buffer in the first transmission is discarded, and the retransmission block transmitted in the second transmission is stored in the buffer instead. On the receiving side, the retransmission block error is detected, and if there is an error, the error is corrected again together with the second retransmission block stored in the buffer. Thereafter, the process is repeated in the same manner.

However, this method has a problem that the algorithm becomes very complicated because the receiving side does not always receive the blocks in a continuous order.

In addition, multipath
When high-speed digital data is transmitted on a fading channel, blocks with many errors may be received continuously for a long period. Even in this case, the retransmitted block was correctly received until it became ACK. There is a problem that the buffer for storing the data is likely to overflow and the buffer capacity becomes huge.

As another solution, A. R. K. S
astry, M .; Moeneclaey, F.M. Arge
There is a series of methods proposed by Nti et al.

A. R. K. The method of Sastry is NAK
Is received, the wrong block is repeated p times consecutively,
This is a method in which the block is retransmitted again in the same procedure only when it is incorrect p times. This system is, for example, IEEE TRANSACTIONS ON CO
MMUNICATIONS COM-23 Volume 4
Issue A. R. K. Satry's paper "Improv
ing Automatic Repeat-Requ
est (ARQ) Performanceon Sa
tellite Channels Under Hi
gh Error Condition ”.

This method is further generalized and a method of optimizing the value of p according to the state of the communication path is described in M.I. Moenecla
proposed by ey et al.

In this method, assuming that p is 2 from the state of the communication path, the same block is retransmitted twice when NAK is returned once, and when NAK is returned twice, the same block is changed this time. The optimum K is selected according to the state of the communication path by transmitting the data three times in succession. This method is based on, for example, IEEE TRANSACTIONS ON COM.
MUNICATIONS COM-34 Vol. The paper "Through" by Moeneclaey et al.
hput Optimization fora Ge
generalized Stop-and-Wait A
RQ Scheme ”.

Further, F. Argenti et al. Continuously transmit blocks in a group with several consecutive blocks as one group, wait for ACK / NAK from the receiving side, and when NAK is received, erroneous blocks among the blocks in the group are received. Resend the block after. As a result, the delay time for retransmission can be shortened and the throughput can be improved. Regarding this method, for example, IEEE
ELECTRONICS LETTERS Vol. 28 No. 9 F. Argenti, G .; Benelli,
A. Garzelli's paper "Generalize"
d Stop-and-Wait Protocol "
It is written in.

F. The method of Argenti et al.
Compared to the A protocol, a considerable improvement in throughput can be expected in a place where the communication path is in good condition. However, the second and subsequent transmissions of this method start with M from the block in error.
Since there is only the second block, it is less efficient than the first transmission.

On the other hand, an error correction code composed of one block of data to be transmitted and a block composed of an error correction parity bit generated based on the block is used to perform error correction for one retransmission request. A block of parity bits for transmission is transmitted one by one, the transmitted signal blocks are added one after another to the previous signal block, and a code using a code that can be a higher correction code is added each time. , For example H.I. Krishna and S.K. Mo
rgera; “A new error contro
l scheme for hybrid ARQ s
system ", IEEE Trans. Commu
n. , Vol. COM-35, no. 10. pp. 98
1-990, Oct. 1987 and the like.

A method using a code that can restore the original signal from the parity bit for error correction generated based on the data to be transmitted is described in, for example, S.
Lin and P.L. S. Yu; "A hybrid
ARQ scheme with parity re
transmission for error co
ntroll of satellite channe
Is ", IEEE Trans. Commun., vo
l. COM-30, no. 7, pp. 1701-171
9, Jul. 1982 and the like.

It is highly possible that the efficiency of error correction can be improved by using such a code in the apparatus.

As another solution, M. J.
Miller et al. Described a method of preventing the overflow of the reception buffer by combining the SR protocol and the GBN protocol. J. Miller and ot
hers: “The Analysis of Som
e Selective-repeat ARQ wi
th Finite Receiver Buffer
r ″, IEEE Trans. Commun., vo
l. COM-29, no. 4 is proposed.

In this system, when operating in the ARQ system of the SR mode, all the blocks which are first judged to have an error by the receiving side are NAK for the ν times of retransmissions and are judged by the transmitting side. In this case, the mode is switched from the SR mode to the GBN mode ARQ method and transmission is performed. Then, the block that is first determined to be erroneous on the transmitting side is ACK.
If it is determined, the mode is returned to the SR mode again and the transmission is performed.

FIG. 16 shows an example in which N = 5 and ν = 1. Explaining this example in detail with reference to the drawings, the receiving side first returns NAK to the transmitting side for the blocks 2, 4, and 7 which are judged to be erroneous by the receiving side, and the transmitting side first sets the SR mode. And resend. As a result, the blocks 2 and 4 are now judged by the receiving side to be error-free,
An ACK is returned to the sender. On the other hand, block 7 is again judged to be an error by the receiving side, so the receiving side NAKs the transmitting side.
return it. On the transmitting side receiving this NAK, the mode is set to SR.
The mode is switched to the GBN mode and transmission is performed. That is, the retransmission block 7 and the following four blocks are transmitted by the GBN protocol until ACK is returned to the block 7. Then, the sender sends A to block 7.
When it is determined that the CK has been received, the mode is returned to the SR mode again and the subsequent blocks are transmitted. This M. J. M
The paper by iller et al.
A combination method of the R protocol and the Stutter (ST) mode in which erroneous blocks are continuously transmitted until an ACK is returned is proposed. This method first operates in the SR mode, and when the block that is determined to have an error at this time is NAK for all v retransmissions, the mode is changed from the SR mode to the ST mode. Switch to the mode and send. Then, the block judged to be erroneous is continuously transmitted, and if ACK is received by the transmitting side, the mode is returned to the SR mode again and the next transmission is performed.

This example is shown in FIG. 17 when N = 4 and ν = 1. Explaining this example with reference to the drawing, with respect to blocks 5 and 7 judged to be erroneous by the receiving side, NAK is returned from the receiving side to the transmitting side, and the transmitting side retransmits again in SR mode. However, since the block 5 also encountered the NAK, the transmission side switches to the SR mode and the color ST mode and continuously retransmits until an ACK is returned to the block 5. Then, when it is determined that the ACK is received on the transmitting side, the mode is returned to the SR mode again and the subsequent transmission is performed.

These M. J. The method proposed by Miller et al. Can prevent the reception buffer from overflowing, but has a drawback that the algorithm becomes complicated because a plurality of logics are switched.

[0028]

[Problems to be Solved] As described above, the conventional ARQ is used.
In the method, in a poor communication state, the capacity of the receiving buffer becomes large, and the phenomenon such as the throughput suddenly deteriorates is seen, and when trying to prevent the overflow of the receiving buffer, the algorithm becomes a little complicated. There were many things.

Therefore, in the present invention, the protocol is as simple as possible with the goal of improving these problems so that digital data communication can be performed by a system having a long RTD such as a satellite communication system using a small portable terminal. Another object of the present invention is to construct a system in which the buffer is as small as possible and the power consumption of the terminal is as small as possible so that the device can be downsized and the throughput can be maximized.

[0030]

In order to achieve the above object, a data transmission device that retransmits data from the transmitting side when the data transmitted from the transmitting side is judged to be erroneous by the receiving side is provided in N blocks. The transmitting means for transmitting the data signals of consecutive M blocks (M <N) and the data signal transmitted by the transmitting means are transmitted to the communication path having the loopback delay time corresponding to the transmission time length of the data signal. For the received M signal blocks, a detection unit that sequentially detects errors using the error detection bits added to each signal block on the transmission side in advance, and an error is detected as a result of the error detection by this detection unit. If not, the block is output to the user and at the same time an acknowledgment is sent back to the sender. If an error is detected, the block is not output and sent. To the response means for sending back the retransmission request response, and when the response returned by the response means is the retransmission request response, M consecutive signal blocks including the signal block in which the error is detected are generated. It is composed of a retransmitting means for retransmitting.

In addition, the data transmission device is configured so that, in response to a retransmission request from the receiving side, the data to be transmitted is blocked, or an error correction parity bit is generated based on the data to be transmitted. After the process of adding an error detection bit to each signal block is performed on the blocked data, the communication path having a folding delay time corresponding to the transmission time length of the N block data signal, Transmitting means for transmitting data signals of consecutive M blocks (M <N) and data transmitted by the transmitting means are received, and the received M signal blocks are added in advance to each signal block on the transmitting side. The detection unit that detects an error using the error detection bit, and if the error is not detected as a result of the error detection by the detection unit, the block is used. Sends back an acknowledgment at the same time transmitting side and outputs the user, M-1 with back a retransmission request in response to the transmission side without outputting the blocks when an error is detected, and subsequent detection signal blocks of the error
The holding means holds the individual signal blocks, and the correction means performs error correction using the retransmitted signal blocks and the signal blocks held by the holding means.

In addition, the data transmission device always transmits signal blocks continuously without waiting for a response signal from the receiving side, and in accordance with a retransmission request from the receiving side, the data to be transmitted which is made into blocks, Alternatively, after processing for adding error detection bits to each signal block is applied to the block-shaped data composed of error-correction parity bits generated based on the data to be transmitted, a continuous constant value is obtained. Number K
Transmitting means for transmitting the signal blocks, and the K signal blocks received by the transmitting means, using the error detecting bits previously added to the signal blocks on the transmitting side for the received K signal blocks. As a result of the error detection by the detection means and the error detection by the detection means, when the error is not detected, the block is output to the user and at the same time an acknowledgment is sent back to the transmission side, and when the error is detected, the error is detected. A resending request response is sent back to the transmitting side without outputting the block, and holding means for holding the signal block in which an error has been detected and K-1 signal blocks following it, and the resending signal block and the holding means hold it. And a correction means for performing error correction using the signal block.

Further, the data transmission device transmits data signals of continuous kN blocks (k is a natural number) to a communication path having a loopback delay time corresponding to the transmission time length of N blocks of data signals. Means for receiving the data signal transmitted by the transmitting means, and detecting means for sequentially detecting the received kN signal blocks by using the error detecting bit added to each signal block on the transmitting side in advance. As a result of error detection by the detection means,
If no error is detected, the block is output to the user and at the same time an acknowledgment is sent back to the sender.If an error is detected, the block is not output and a resend request response is sent back to the sender. , A re-transmission unit that immediately re-transmits a signal block in which an error is detected when the response sent back by the response unit is a resend-request response, and all of the kN signal blocks are configured. Is retransmitted by the retransmitting means until the response from the receiving side becomes a confirmation response, and after the transmission of all kN signal blocks is completed, the transmitting means newly continues kN.
Send the data signal of the block.

Further, the data transmission device transmits data signals of continuous kN blocks (k is a natural number) to a communication path having a loopback delay time corresponding to the transmission time length of data signals of N blocks. Means for receiving the data signal transmitted by the transmitting means, and detecting means for sequentially detecting the received kN signal blocks by using the error detecting bit added to each signal block on the transmitting side in advance. As a result of error detection by the detection means,
If no error is detected, the block is output to the user and at the same time an acknowledgment is sent back to the sender.If an error is detected, the block is not output and a resend request response is sent back to the sender. , If the response sent back by the response means is received and the response is a resend request response, the signal block in which the error is detected is immediately retransmitted, and is transmitted between the block to be retransmitted and the block to be transmitted next. When there is a blank time, the re-transmitting block is configured to be continuously transmitted during the blank time, and the re-transmitting means is used until all the kN signal blocks are acknowledged by the receiving side. Retransmission is performed, and after transmission of all kN signal blocks is completed, the transmission means transmits a new continuous kN block of data signals.

Further, here, the correction means is an error correction code composed of one block of data to be transmitted and a parity bit for error correction generated based on the block, and is retransmitted once. Blocks consisting of parity bits for error correction are transmitted one by one in response to the request, and the transmitted signal blocks are added to the previous signal block one after another up to a maximum of L-1 blocks, and corrected each time they are added. It is realized by using a code that can be a higher code.

Further, the parity bit for error correction is generated based on the data to be transmitted, and is realized by using the parity bit which is characterized in that the original information can be restored from itself.

Further, by changing the natural number k of the transmitting means according to the communication state of the communication path, the number of blocks to be transmitted at one time can be adaptively changed.

Further, a measuring device for estimating or measuring the error rate of the block transmission is provided on the transmitting side or the receiving side, and the error rate estimation or measurement result by the measuring device is lower than a predetermined prescribed value. In some cases, even if the retransmission means receives the retransmission request response, it is processed as an acknowledgment.

[0039]

In the data transmission device of the present invention, the same number of consecutive blocks as the first transmission is transmitted during the second and subsequent transmissions performed in response to the transmission request.
Also, data and parity bits are combined for each transmission request so that a code with higher correction capability is used, and the parity bit for error correction can restore the original information from itself. Was used. Therefore, high throughput can be achieved even with a simple protocol and a relatively short buffer.

[0040]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows a signal transmission procedure of an embodiment of the present invention, which is based on the F.S. An improved version of the Argenti et al. Scheme is shown.

Returning delay time (RTD) in FIG.
Assuming that N blocks can be transmitted in one block, M blocks (M <N) that are continuous in one transmission are set as a group, and the first M blocks are continuously transmitted in the first transmission. , The receiving side sequentially performs error detection on this M block,
Send back ACK / NAK.

Now, assuming that an error is detected in the i-th block, the i-th block to the M-th block are discarded, and the NA for the i-th block is discarded on the transmitting side.
K is returned. At the sending side that received the NAK, i
Block to M-th block followed by i +
The first to M + i−1th blocks are transmitted. On the receiving side, error detection is sequentially performed as in the case of the first time, and ACK / NAK is sent back. The above process is repeated until all the blocks are received.

In this embodiment, since the same number of consecutive blocks as in the first transmission is transmitted in the second and subsequent transmissions, it is possible to simplify the algorithm compared with the conventional method while maintaining high throughput, and It is possible to prevent overflow and prevent a sudden deterioration in throughput in a poor communication state.

Further, by combining this system with an error correction code efficiently, it is possible to prevent a rapid deterioration of throughput when the state of the communication path is bad.

FIG. 2 shows a transmission procedure of another embodiment of the present invention. Here, a case of N = 5 and M = 2 will be described. Further, FIG. 3 shows the contents of processing for each block in FIG.

In the example of FIG. 2, if no error is detected on the receiving side, ACK is returned and the received content is output to the user as it is. When an error is detected in the i-th block, the receiving side returns NAK to the transmitting side, and the block i,
Save (i + 1) in the buffer. The transmitting side receiving the NAK transmits the retransmission blocks i ′ and (i + 1) ′ of the block i and (i + 1) in the second transmission.

Here, retransmission blocks i ', (i + 1)'
Are the blocks i and (i + 1) transmitted for the first time.
Is a parity bit of an error correction code having information bits.

Next, error correction is performed by combining the first transmission block i and the second retransmission block i '. Here, as the error correction code, a code that can be a code having a higher correction capability by adding parity bits one after another is used.

As a result of the error correction, if the error can be corrected, ACK is returned. If the error cannot be corrected, NAK is returned to the transmitting side and the third retransmission block i ″ is received. Then, the blocks i, i ′, i ″ are combined to perform error correction. Such an operation is repeated until the error can be corrected or until the maximum L-1 blocks of parity bits are added. If the error can be corrected, block i is output to the user and ACK is returned to the sender.

On the other hand, after the block (i + 1) is received, the same processing as that of the block i is performed. And block i
If the processing is completed before that, it is stored in the buffer and output after the processing of block 3 is completed.

FIGS. 3A and 3C are block 3, FIG.
(F) and (g) show the case where the error correction is successful for the block 5 by combining the first transmission block and the second retransmission block. 3 (b), (d) and (e) show the case where the error is corrected in the third retransmission for block 4.

In FIGS. 3A to 3H, 10 to 14 are used.
Indicates a process, and 20 and 21 indicate a judgment, and the same expressions are used in the subsequent figures.

As a result, the error correction code having the minimum necessary correction ability can be constructed and corrected according to the error level. The size of the buffer may be M. (L-1) blocks.

FIG. 4 shows a transmission procedure of still another embodiment of the present invention. FIG. 5 shows the contents of the processing at each timing of FIG.

Also in this example, N = 5. M = 2
The case will be described. In FIG. 4, if no error is detected in the first transmission, ACK is returned and the received content is output to the user as it is. When an error is detected, NAK is returned to the sender, and then the following process is performed. That is, first, the block i and the subsequent block (i + 1) are stored in the buffer. And NA
On the transmitting side receiving K, the block i ′ is transmitted in the second transmission,
(I + 1) 'is transmitted.

Here, the retransmitted blocks i'and (i + 1) 'are composed of parity bits of an error correction code having the blocks i and (i + 1) transmitted at the first time as information bits. These retransmitted blocks are the received blocks i ′.
If no error is detected in, the parity inverter restores block i and outputs it to the user.
(This operation procedure is shown in the case of blocks 5 and 5'in FIGS. 5 (f) and 5 (g).) Also, the received block i
If an error is detected in ', the error correction is performed in combination with the block i stored in the buffer, as indicated by block 3 in FIG. 5 (c). If there is still an error, the block i stored in the buffer is discarded and the block i ′ transmitted the second time is stored instead. At the same time, NAK is returned to the transmitting side, and blocks i and (i + 1) are transmitted from the transmitting side as the third retransmission block.
On the receiving side, the error of the retransmitted block i is detected, and if there is no error, it is output to the user as it is, and if there is an error, the error is corrected together with the block i ′ stored in the buffer. (This operation procedure is shown in the case of blocks 4 and 4'in FIGS. 5D and 5E.) Thereafter, the process is repeated in a similar manner.

On the other hand, the block (i + 1) is subjected to exactly the same processing as the block i after reception. If the processing is completed before the block i, it is saved in the buffer,
It is output after the processing of the block i is completed.

According to this method, the size of the buffer on the receiver side may be M blocks. Further, even in the second and subsequent transmissions, the efficiency can be improved by transmitting the same number of continuous blocks as in the first transmission.
Further, even if the condition of the communication path deteriorates, the throughput does not rapidly deteriorate, and it is possible to efficiently transmit even in a place where the condition of the communication path is poor.

FIG. 6 is a diagram for explaining still another embodiment of the present invention. Here, Go-Back-N (GBN) AR
The present invention is applied to the Q method. In this case, the blocks are continuously transmitted even during the return delay time (RTD). Let M be the number of blocks that can be transmitted during RTD, and M
The case of = 2 will be described.

In FIG. 6, if no error is detected on the receiving side, ACK is returned and the received contents are output to the user as they are. If an error is detected in block i,
Returns NAK and stores block i, (i + 1) in the buffer. On the transmitting side that has received NAK, the retransmitted blocks i ′ and (i + 1) ′ of block i and (i + 1) are transmitted in the second transmission.
To send. Here, the retransmitted blocks i ′ and (i + 1) ′ are composed of parity bits of an error correction code having the blocks i and (i + 1) transmitted at the first time as information bits.

In the processing of these retransmission blocks, the error correction is performed by combining the first transmission block i and the second transmission block i '. The contents of the processing during this period are shown in FIG.
The block i is shown as a block 3 in FIG.

Here, the error correction code is a code composed of one block of data to be transmitted and L-1 blocks consisting of parity bits of the error correction code generated on the basis of 1 block. A block composed of a parity bit is transmitted for each retransmission request one by one, and the transmitted blocks are successively added up to L-1 blocks to the previous block, and the correction capability is high each time they are added. Is the code.

If the error cannot be corrected by combining the first transmission block i and the second transmission block i'and correcting the error, NAK is returned to the transmitting side and the third retransmission block i is returned. ", (I + 1)" is received. Then, the blocks i, i ', and i "are combined to perform error correction.
This operation is repeated until the error can be corrected or at least L-1 blocks of parity bits are added.

When the error can be corrected, block i is output to the user and ACK is returned to the transmitting side. The sender receives the ACK and sends a new block (i + 2).

In the meantime, after receiving the block (i + 1), the same processing as that of the block i is performed. And block i
If the processing is completed before that, it is stored in the buffer, and is output after the processing of the block i is completed.

With this method, it is possible to correct an error by constructing an error correction code having a necessary minimum correction capability according to the level of error due to multipath fading or the like. The size of the buffer may be M · (L−1) blocks.

The present invention also relates to R. A. Comroe, D.M.
J. It can also be applied to a method similar to the method of Costello et al. FIG. 8 is a diagram showing another embodiment of the present invention used in this way. Here, the number M of blocks transmitted during RTD is set to M = 2. In FIG. 8, blocks for which no error has been detected in the first transmission are output to the user as they are.

When an error is detected in the block i, NAK is returned to the transmitting side, and first, the block i and the subsequent block (i + 1) are stored in the buffer. Then, the transmitting side receiving NAK transmits blocks i ′, (i +
1) 'is transmitted. Here, retransmission block i ′, (i +
1) ′ are the blocks i, (i
+1) is the parity bit of the error correction code having information bits. These retransmission blocks are block i '
If no error is detected in, the parity inverter restores block i and outputs it to the user. When an error is detected in the block i ′, the error correction is performed together with the block i stored in the buffer.

If the error is still not correct, the block i stored in the buffer is discarded, and the block i'transmitted the second time is stored instead. At the same time, NAK is returned to the transmission side, and blocks i and (i + 1) are sent from the transmission side as the third retransmission block.

On the receiving side, the error of the retransmitted block i is detected, and if there is no error, it is output to the user as it is, and if there is an error, the error is corrected together with the block i ′ stored in the buffer. Thereafter, the process is repeated in the same manner.

On the other hand, after the block (i + 1) is received, the same processing as that of the block i is performed. If the processing is completed before the block i, it is saved in the buffer,
It is output after the processing of the block i is completed. The processing during this time is shown in FIGS. 9A to 9G when i is 3, 4, and 5.

According to this method, the size of the buffer on the receiving side may be M blocks.

As can be seen from the above embodiments, in the present invention, consecutive blocks are retransmitted, so that it is possible to realize processes such as retransmission and code correction with a simpler algorithm than the conventional method. Moreover, overflow does not occur even if the buffer capacity is small.

FIG. 10 shows still another embodiment of the present invention. This method is an improvement of the mode switching method that combines the SR method and the SAW method.

In FIG. 10, the return delay time (RT
Assuming that N blocks can be transmitted in D), a frame having a frame length M = kN blocks (k is a natural number) is formed. The transmitting side continuously transmits these M blocks, and the receiving side sequentially performs error detection, and ACK or NA
K will be returned. The transmitting side retransmits only the block that received the NAK. Then, this procedure is repeated until ACKs are returned from all M blocks, and when the transmission of M blocks is completed, the block of the next frame is transmitted. In this method, the size of the buffer may be a maximum of kN blocks. Also, the value of this k is determined in accordance with the state of the communication path,
When the condition of the communication path is good and there are few errors, k is increased, and when the condition of the communication path is bad, it is decreased to improve the transmission efficiency. .

FIG. 11 shows an example shown in FIG. 10 for k = 2. In FIG. 11, 2N blocks are continuously transmitted in order from the transmitting side, the receiving side sequentially performs error correction on the received blocks, and the transmitting side performs NAK for blocks i and 2N, and for other blocks. ACK is returned. On the sending side, NA
When K is received, the block is retransmitted immediately. Retransmission is continued until ACKs are returned to the transmitting side for both blocks i and 2N, and when ACKs are returned for all blocks, the next 2N blocks are transmitted in the same procedure.

FIG. 12 is a diagram showing still another embodiment of the present invention. FIG. 12 shows the case of k = 2 as in the case of FIG. In FIG. 12, 2N from the transmitting side
It is assumed that the blocks are sequentially and sequentially transmitted, the receiving side sequentially performs error correction on the received blocks, and returns NAK to the blocks i and 2N and ACK to the other blocks. Upon receiving the NAK, the transmitting side immediately retransmits the block. As a method of retransmitting a block, in FIG. 11, a period in which nothing is transmitted from the transmitting side continues between the transmission of the block i and the transmission of the block 2N, and the block 2N is retransmitted and the block i is retransmitted. The blank period will continue until
2, the block i is continuously retransmitted until the block 2N is retransmitted after the block i is retransmitted, and the block 2N is continuously transmitted until the block i is retransmitted after the block 2N is retransmitted. Keep re-sending to. By doing so, the number of retransmissions can be reduced and the transmission efficiency can be further improved.

In the above examples of FIGS. 10 to 12, the frame length M can be changed according to the state of the communication path.
By transmitting not only the frame length M but also the length of one block with an optimum value, it is possible to perform transmission efficiently in a communication path in which the state changes drastically.

FIG. 13 shows one embodiment using such a method.

FIG. 13 shows the case of M = 3N.
In this example, since the results of transmission from block 1 to block N are all ACK, the transmission side determines that the transmission state is good, and the remaining N blocks have twice the block length, that is, 2 blocks. A new one
Send as a block. Then, when the transmission of all blocks is completed without error, the next M blocks are all transmitted in a new block unit of two blocks. Then, while watching the communication state, if the situation becomes worse, the original block length may be restored and transmission may be performed. If it is determined that the situation is better, the block length may be further extended and transmission may be performed.

In any of the above embodiments,
If the block error rate is smaller than the specified value, ACK is ignored even if there is a NAK response.
It is also possible to adopt a method in which the same processing as in the above case is performed on the transmitting side and the receiving side. By doing so, when the communication state is very good, the communication speed can be dramatically increased while allowing some errors.

[0083]

As described above, in the data transmission apparatus of the present invention, the same number of consecutive blocks as the first transmission is transmitted during the second and subsequent transmissions performed in response to the transmission request. In addition, the data and the parity bit are combined for each transmission request so that the code having the higher correction capability is used, and the parity bit for error correction uses the original information from itself. I used the one that can be restored. If all the consecutive blocks are correctly received, the next consecutive block is transmitted, and if there is an error, only that block is retransmitted. By using such a method, it is possible to prevent the rapid deterioration of the throughput even in a poor communication path state, and it is possible to improve the throughput. In addition, the algorithm can be simplified, the buffer can be of a finite length, and the optimal number of transmission blocks can be set according to the state of the communication path, so the circuit scale can be reduced and the power consumption of the terminal can be suppressed. it can.

[Brief description of drawings]

FIG. 1 is a diagram showing a transmission procedure according to an embodiment of the present invention.

FIG. 2 is a diagram showing a transmission procedure of another embodiment of the present invention.

FIG. 3 is a diagram showing a block processing method on the receiving side in the embodiment whose transmission procedure is shown in FIG. 2;

FIG. 4 is a diagram showing a transmission procedure of still another embodiment of the present invention.

5 is a diagram showing a block processing method on the receiving side in the embodiment whose transmission procedure is shown in FIG. 4;

FIG. 6 is a diagram showing a transmission procedure of still another embodiment of the present invention.

FIG. 7 is a diagram showing a block processing method on the receiving side in the embodiment whose transmission procedure is shown in FIG. 6;

FIG. 8 is a diagram showing a transmission procedure of still another embodiment of the present invention.

9 is a diagram showing a block processing method on the receiving side in the embodiment whose transmission procedure is shown in FIG. 8;

FIG. 10 is a diagram showing a transmission procedure of still another embodiment of the present invention.

11 is a diagram showing a specific example of the transmission procedure of the embodiment of FIG.

FIG. 12 is a diagram showing a transmission procedure of still another embodiment of the present invention.

FIG. 13 is a diagram showing a transmission procedure of still another embodiment of the present invention.

FIG. 14 is a diagram showing a transmission procedure of Type II hybrid ARQ in SR mode which is a conventional example.

15 is a diagram showing a block processing method on the receiving side in the conventional example whose transmission procedure is shown in FIG.

FIG. 16 is a diagram showing a transmission procedure of a conventional example according to a switching method between SR mode and GBN mode.

FIG. 17 is a diagram showing a transmission procedure of a conventional example according to a switching method between SR mode and ST mode.

[Explanation of symbols]

 ACK Positive response (confirmation response) NAK Negative response (resend request response) 10-14 Processing 20, 21 Judgment

Claims (9)

[Claims] 1. A data transmission device that retransmits data from a transmitting side when data transmitted from the transmitting side is judged to be erroneous by the receiving side, and a loopback corresponding to a transmission time length of a data signal of N blocks. Transmitting means for transmitting data signals of consecutive M blocks (M <N) to a communication path having a delay time, and M signal blocks received for receiving the data signals transmitted by the transmitting means Detection means for sequentially detecting errors using the error detection bits added to each signal block in advance on the transmission side, and as a result of the error detection by the detection means, if no error is detected, the block is presented to the user. At the same time as outputting, an acknowledgment response is sent back to the sender, and if an error is detected, the block is not output and a resend request response is sent back to the sender. And a step of receiving the response sent back by the response means, and if the response is a retransmission request response, a retransmission of retransmitting M consecutive signal blocks including a signal block in which an error is detected. A data transmission device comprising means. 2. A data transmission device that retransmits data from the transmitting side when data transmitted from the transmitting side is judged to be erroneous by the receiving side, and is divided into blocks according to a retransmission request from the receiving side. The data to be transmitted, or the block data composed of the parity bits for error correction generated based on the data to be transmitted, is subjected to the processing of adding the error detection bit to each signal block. And transmitting means for transmitting the data signals of consecutive M blocks (M <N) to the communication path having the loopback delay time corresponding to the transmission time length of the data signals of N blocks, and the transmission means. The received data, and detects an error in the received M signal blocks by using the error detection bit added to each signal block on the transmission side in advance. And a detection unit that detects the error, if no error is detected, the block is output to the user and at the same time an acknowledgment is sent back to the transmission side, and when the error is detected, the block is detected. Holding means for holding a signal block in which an error has been detected and the subsequent M-1 signal blocks, and holding the retransmitted signal block and the holding means. And a correction means for performing error correction using the signal block. 3. A data transmission device that retransmits data from the transmitting side when data transmitted from the transmitting side is determined to be erroneous by the receiving side, without waiting for a response signal from the receiving side to continuously perform continuous transmission. Signal block is transmitted, and in response to a retransmission request from the receiving side, it is divided into blocks to be transmitted, or a block composed of parity bits for error correction generated based on the data to be transmitted. After performing a process of adding an error detection bit to each signal block to the data, the transmitting unit that transmits a constant number of K signal blocks in succession, and the data transmitted by the transmitting unit are received. Detecting means for detecting an error in the received K signal blocks by using the error detecting bit previously added to each signal block on the transmitting side; If no error is detected as a result of error detection by, the block is output to the user and at the same time an acknowledgment is sent back to the sender, and if an error is detected, the block is not output and a resend request is sent to the sender. An error is generated by using a holding unit that sends back a response and holds the signal block in which an error has been detected and K-1 signal blocks following it, and the retransmitted signal block and the signal block held by the holding unit. A data transmission device comprising a correction means for making a correction. 4. In a data transmission device that retransmits data from the transmission side when the data transmitted from the transmission side is judged to be erroneous by the reception side, a loopback corresponding to the transmission time length of the data signal of N blocks. A transmitting unit that transmits continuous kN blocks (k is a natural number) of data signals to a communication path having a delay time, and kN signal blocks that have been received by receiving the data signals transmitted by the transmitting unit. Detection means for sequentially detecting errors using the error detection bits added to each signal block in advance on the transmission side, and as a result of the error detection by the detection means, if no error is detected, the block is presented to the user. At the same time as outputting, an acknowledgment is sent back to the sender, and if an error is detected, the block is not output and a resend request response is sent back to the sender. A response unit for receiving the response returned by the response unit, and when the response is a retransmission request response, a retransmission unit for immediately retransmitting the signal block in which an error is detected, The kN signal blocks are retransmitted by the retransmitting means until the response from the receiving side becomes an acknowledgment response, and after the kN signal blocks are completely transmitted, the transmitting means is newly continuous. A data transmission device characterized by transmitting a data signal of a kN block. 5. In a data transmission device that retransmits data from the transmission side when the data transmitted from the transmission side is determined to be erroneous by the reception side, a loopback corresponding to the transmission time length of a data signal of N blocks. A transmitting unit that transmits continuous kN blocks (k is a natural number) of data signals to a communication path having a delay time, and kN signal blocks that have been received by receiving the data signals transmitted by the transmitting unit. Detection means for sequentially detecting errors using the error detection bits added to each signal block in advance on the transmission side, and as a result of the error detection by the detection means, if no error is detected, the block is presented to the user. At the same time as outputting, an acknowledgment is sent back to the sender, and if an error is detected, the block is not output and a resend request response is sent back to the sender. And a response unit that receives the response sent back by the response unit, and if the response is a retransmission request response, immediately retransmits the signal block in which an error is detected, When there is a transmission blank time between the blocks to be transmitted, there is provided re-transmission means for continuously transmitting the re-transmission block at the blank time, and a response from the reception side for all of the kN signal blocks. Is re-transmitted by the re-transmitting means until a confirmation response is received, and after the transmission of all the kN signal blocks is completed, the transmitting means transmits a new continuous kN-block data signal. Data transmission equipment. 6. The error correction code, wherein the correction means is composed of a block of data to be transmitted and a parity bit for error correction generated based on the block, and a single retransmission request. , A block composed of parity bits for error correction is transmitted one by one, and the transmitted signal blocks are successively added to the previous signal block up to a maximum of L-1 blocks, and a correction code is added each time. The data transmission device according to claim 2 or 3, wherein the data transmission device is realized by using a code that can be a higher code. 7. A parity bit for recovering the original information from itself is used as the error-correction parity bit generated based on the data to be transmitted. Item 6. The data transmission device according to any one of items 2 to 5. 8. The number of blocks to be transmitted at one time can be adaptively changed by changing the natural number k according to the communication state of the communication path. 4. The data transmission device according to 4 or 5. 9. A measuring device for estimating or measuring an error rate of block transmission is further provided on the transmitting side or the receiving side, and an error rate estimation or measurement result by the measuring device is lower than a predetermined prescribed value. 9. The data transmission apparatus according to claim 1, wherein when the value is a value, the re-transmission unit processes the retransmission request response as the confirmation response even if the retransmission request response is received.