CN1914845B - Method for generating feedback message for automatic repeat request in mobile communication system - Google Patents

Abstract

A method for generating a feedback message for ARQ, the method includes: a) recording an ACK type in a first field; b) estimating the last block sequence number of successively ACKed blocks and recording the estimated last block sequence number in a second field; c) recording the number of groups of successively ACKed blocks after the block sequence number estimated in b) as the number of ACK MAPs in a third field; d) recording the startblock sequence number of the respective ACK MAPs in a fourth field; e) recording the lengths of the respective ACK MAPs in a fifth field corresponding to the start block sequence number in d); and f) sending a feedback message including information on the first to the fifth fields.

Description

Method for generating feedback message for automatic repeat request in mobile communication system

technical field

The present invention relates to a method for generating feedback messages and reducing overhead (overhead) in a wireless mobile communication system, in particular, the present invention relates to utilizing automatic repeat request (ARQ) feedback messages in a newly defined ACK map to reduce overhead The resend request algorithm.

Background technique

In wireless mobile Internet systems, Automatic Repeat Request (ARQ) algorithms have been developed to reduce error rates and enhance error correction capabilities in data transmission.

The ARQ algorithm is used as a method of retransmitting a damaged data packet with reference to feedback information (ACK and NACK) of each transmitted data packet or in consideration of a timeout in which a corresponding feedback message is not received.

FIG. 1 is a block diagram illustrating an ARQ transmitter and an ARQ receiver.

The transmitter 10 transmits Protocol Data Units (PDUs) to the receiver according to the ARQ mechanism. PDUs are generated from Service Data Units (SDUs) generated from the upper layer 11 and stored in the buffer 12 .

The ARQ receiver 23 sends a feedback message for ARQ to the transmitter 10 . The feedback message to ARQ includes an ACK or NACK message according to the success or failure of transmission of the PDU, and is used for error correction of the mobile Internet system.

The ARQ transmitter 13 retransmits the corresponding PDU to the ARQ receiver 23 in response to the ACK message or the NACK message, or transmits a discard message.

Therefore, the transmitter 10 can use the result of the ARQ indicating whether the transmission is successful or failed to analyze the data transmission efficiency according to the receiver or the channel quality. QoS analysis and scheduling can be obtained by referring to data transmission efficiency.

FIG. 2 is a diagram illustrating a signal flow according to a conventional ARQ method.

When the transmitter 10 sends a data packet to the receiver, the receiver sends an ACK message to the transmitter as a feedback message for ARQ after receiving the data packet. ACK messages include cumulative ACK messages and selective ACK messages, which will be described below.

When the ARQ receiver 23 successfully receives the data packet, the ARQ receiver 23 sends an ACK message to the ARQ transmitter 13, but when data is lost due to poor channel quality, the ARQ receiver may not be able to receive the data packet.

The transmitter may also not receive the ACK message from the ARQ receiver 23 when the ACK message is lost due to poor channel quality. Once a data packet or ACK message is lost, the ARQ receiver preferably discards the corresponding data packet after a predetermined lifetime so that the ARQ sender does not wait indefinitely for an acknowledgment or retransmit the data packet.

Conventionally, in step S1, the ARQ transmitter 13 sends a discard message to the ARQ receiver when a data packet or ACK message is lost on the channel, so the transmitter 10 does not receive any ACK message within a predetermined lifetime.

In step S2, the ARQ receiver 23 sends a discard acknowledgment message in response to the discard message, and discards the transmitted data packet.

3 to 5 illustrate the formats of ARQ feedback messages in a wireless mobile Internet system, respectively.

Figure 3 shows a selective ACK message.

In Fig. 3, it is assumed that in the wireless mobile Internet system, a medium access control (MAC) layer PDU (MAC PDU) containing 12 sequence blocks is sent to the receiver, and in the fourth, seventh, eighth and tenth An error occurred in the second sequence block. The ARQ receiver sends an ACK MAP as a feedback message to ARQ in response to the transmitted MAC PDU. The ACK image maps reception success to 1 and reception error or failure to 0. The ARQ transmitter receives the ACK map, and retransmits those blocks mapped with sequence numbers of 0 to the ARQ receiver.

Figure 4 shows cumulative ACK messages.

When an error occurs in the sequence block numbers (BSN) 4, 7, 8, and 12 of the MAC PDU as shown in Figure 3, the ARQ receiver records the number of consecutive blocks sent without errors in the feedback message to ARQ. A sequence (BSN1, 2 and 3) to generate corresponding feedback messages on ARQ.

As shown in Figure 4, the ARQ receiver then sends an ACK to inform the ARQ receiver that BSN1, 2, and 3 were successfully received, and the ARQ transmitter retransmits the blocks from BSN4 to BSN12 of the MAC PDU.

Figure 5 shows selective and cumulative ACK messages.

Although the selective ACK message of FIG. 3 is efficient since only blocks with errors are retransmitted, both the data processing time and the size of the ACK map problematically increase. For feedback messages, the cumulative ACK message shown in Figure 4 requires less capacity and provides very fast processing time, but increases the data size to be retransmitted.

In Fig. 5, by taking advantage of the selective ACK message and the cumulative ACK message, the ARQ receiver sends the ARQ transmitter the ACK feedback message containing the successfully received BSN (BSN 1, 2, 3) and the information from BSN4 to BSN12 to the ARQ transmitter. Remapped ACK image to request retransmission.

However, since a series of consecutive blocks forms a PDU, and data transmission success or failure occurs in each PDU, the above feedback message for ARQ is not effective in a wireless mobile Internet system.

In other words, conventional bitmap-type ACK maps map the success and failure of each BSN, thereby increasing overhead.

Therefore, there is a need for an efficient method for transmitting a feedback message for ARQ without increasing overhead in a wireless mobile Internet system.

Contents of the invention

The object of the present invention is to provide a method for generating feedback messages and reducing overhead in a wireless mobile Internet system.

In one aspect of the present invention, a method for generating a feedback message for an automatic repeat request (ARQ) is provided. In this method, a) record the ACK type in the first field; b) estimate the last block sequence number of the cumulative ACK block and record it in the second field; c) the block sequence number to be estimated in b) The group number of the subsequent continuous ACK blocks is recorded in the third field as the number of ACK images; d) the starting block sequence number of each ACK image is recorded in the fourth field; e) by combining the length with d) The start block sequence number corresponds to record the length of each ACK image.

In another aspect of the present invention, a method of generating a feedback message for an automatic repeat request (ARQ) is provided. In this method, a) record the ACK type in the first field; b) estimate the last block sequence number of consecutive ACK blocks and record it in the second field; c) put the block sequence number estimated in b) after The number of groups of consecutive ACK blocks or NACK blocks is recorded in the third field as the number of macroblocks (bulk); d) set and record the type of each macroblock; e) estimate and record the number of each macroblock in the fourth field type length.

In c), the number of macroblocks is set by selecting a group from groups having a predetermined number of macroblocks.

The bits of the macroblock length allocated to groups each having a predetermined number of macroblocks are different for each group.

According to the present invention, the overhead of conventional ARQ feedback messages is reduced, and an effective packet retransmission request is notified.

Description of drawings

The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate embodiments of the invention and together with the description serve to explain the principles of the invention, in which:

FIG. 1 is a block diagram illustrating an ARQ transmitter and an ARQ receiver;

FIG. 2 is a diagram illustrating a signal flow of a conventional ARQ method;

Figure 3 shows a selective ACK message;

Figure 4 shows cumulative ACK messages;

Figure 5 shows a selective cumulative ACK message;

Figure 6 schematically shows the generation of ACK or NACK messages;

Fig. 7 shows the mode of ACK/NACK according to the embodiment of the present invention;

FIG. 8 illustrates the structure of an ARQ feedback message according to an embodiment of the present invention;

FIG. 9 illustrates the structure of an ACK map according to a second embodiment of the present invention;

FIG. 10 illustrates the structure of an ACK map according to another embodiment of the present invention;

FIG. 11 illustrates the structure of an ACK map according to another embodiment of the present invention;

Fig. 12 illustrates the structure of the ACK map according to another embodiment of the present invention;

FIG. 13 illustrates the structure of an ACK map according to another embodiment of the present invention;

FIG. 14 illustrates the structure of an ACK map according to another embodiment of the present invention;

FIG. 15 illustrates a method for generating an ARQ feedback message according to an embodiment of the present invention; and

FIG. 16 illustrates a flowchart of a method for transmitting an ARQ feedback message according to another embodiment of the present invention.

Detailed ways

In the following detailed description, there are shown and described preferred embodiments of the invention, simply by way of illustration of the best mode of carrying out the invention. As will be realized, the invention is capable of modification in various obvious respects, all without departing from the invention. Accordingly, the drawings and descriptions are to be regarded as illustrative and not restrictive. In order to clarify the present invention, parts that are not described in the specification are omitted, and the same reference numerals are assigned to parts with the same description.

A method for generating a feedback message for an automatic repeat request (ARQ) according to an embodiment of the present invention will be described.

FIG. 6 is a block sequence diagram schematically illustrating a method for generating an ACK or NACK message.

A Service Data Unit (SDU) transmitted from an upper layer of a Medium Access Control (MAC) layer is stored in a buffer and transmitted in the form of a Protocol Data Unit (PDU) having a plurality of sequence blocks. Here, each sequential block is identified by a block sequence number (BSN). The number of sequence blocks in a PDU varies with respect to time through the control of the ARQ receiver. As shown in Figure 6, the success or failure of each transmission may include a certain number of sequence blocks of the relevant PDU, and the sequence blocks in the PDU are identified according to the success and failure of the corresponding transmission caused in the transmission sequence block in the wireless mobile Internet system Whether it is success or failure.

For example, it was found that the three sequence blocks contained in PDU 1 were received successfully, but the reception of the four sequence blocks contained in PDU2 failed.

FIG. 7 illustrates patterns of ACK/NACK according to an embodiment of the present invention.

In this mode, '1' indicates a sequential block that is ACKed, '0' indicates a sequential block that is NACKed, '1' indicates the first cumulative ACK tail block, and '[1]' indicates that the second cumulative ACK starts start block.

In other words, similar to typical cumulative ACK details, the first cumulative ACK message indicates the successfully received BSN, and when the PDUs after the first cumulative ACK tail block are NACKed, the second cumulative ACK message indicates the first cumulative ACK message. Two cumulative ACK start blocks. Furthermore, the length of the second cumulative ACK message shows successfully received data.

Therefore, according to an embodiment of the present invention, the length of the sequence block in the first BSN and the second cumulative ACK message is defined as an ACK map.

In order to distinguish the ACK map from the regular ACK map in FIGS. 3 and 5 , the regular ACK map is referred to as a bitmap below.

As shown in FIG. 7 , the bitmap needs 4 bytes to construct the ACK/NACK of each block, while the ACK map of the present invention only needs 2 bytes, thus making the overhead of the ARQ feedback message lower.

Figure 8 is the syntax of the ARQ feedback message incorporating the ACK map of the present invention. The ARQ feedback message includes the following fields: a connection identifier (CID) identifying the MAC connection; LAST indicating the last feedback message to ARQ in the list; ACK type indicating the ACK type; indicating the last BSN in the sequence block being ACKed BSN; an ACK map number indicating the number of ACK maps; and an ACK map providing information on the corresponding ACK map.

A connection is defined as a mapping relationship between MAC peer-to-peer units in a wireless mobile Internet system. Therefore, the CID includes reference information for dedicating a connection to a feedback message for ARQ. However, the CID is not required when the channel is dedicated to feedback messages for ARQ.

When the corresponding feedback message for ARQ is not the last one, LAST is set to '0', and when the feedback message for ARQ is the last one, LAST is set to '1'.

The ACK type determines the type of ACK for the ARQ feedback message. For example, '0' indicates selective ACK, '1' indicates cumulative ACK, '2' indicates cumulative selective ACK, and '3' indicates cumulative macroblock ACK. Cumulative macroblock ACK corresponds to ACK according to an embodiment of the present invention.

The last BSN in the block of the first sequence that was successfully received is recorded in the BSN field of FIG. 8 .

The number of ACK maps is recorded in the ACK map number. The number of ACK images can be set from 1 to 4. When the ACK type is set to 1 (ie, cumulative ACK), since ACK maps are not required, the number of ACK maps is set to 0.

Information on the ACK map is recorded in units of 16 bits in the corresponding ACK map field.

FIG. 9 illustrates the structure of the ACK MAP field according to the first embodiment of the present invention.

The ACK Map field includes 11-bit BSN information and 5-bit length information. The BSN field of the ACK map corresponds to the starting BSN of the corresponding consecutive ACKs having the size indicated by the length. The length field indicates the number of blocks counted from the BSN of the ACK map to the last BSN of consecutively ACKed blocks.

Meanwhile, the BITMAP field indicates bitmap information of ACK and NACK messages when the ACK type is set to 0 (selective ACK) or 2 (cumulative-selective ACK).

Accordingly, the first cumulative ACK and consecutive ACKs after the first cumulative ACK can be efficiently transmitted by using the ACK map. The ACK map includes start BSN and length information, thereby reducing the overhead of feedback messages for ARQ compared to conventional ACKs using bitmaps.

The ACKed blocks are transmitted by using the ACK map according to the above-described embodiment of the present invention, while successive ACKs and NACKs are respectively defined by using different ACK maps according to another embodiment of the present invention.

FIG. 10 illustrates the structure of an ACK map according to the second embodiment of the present invention.

The ACK map field includes a 3-bit macroblock type field, a 5-bit first macroblock length field, a 4-bit second macroblock length field, and a 4-bit third macroblock length field.

Here, the macroblock type field defines whether the first, second, and third macroblocks are ACKed or NACKed, respectively. For example, when the macroblock type field is set to '010', it informs that the first macroblock is NACKed, the second macroblock is ACKed, and the third macroblock is NACKed.

The respective length fields of the first to third macroblocks indicate the number of blocks contained in the respective macroblocks.

FIG. 11 illustrates the structure of an ACK map according to a third embodiment of the present invention.

The structure in the third embodiment is similar to that of the second embodiment shown in FIG. 10 except that 4 bits are equally allocated to the length fields of the first, second, and third macroblocks.

FIG. 12 illustrates the structure of an ACK map according to a fourth embodiment of the present invention.

The macroblock configuration field is used to indicate the number of macroblocks in the ACK map.

For example, when the number of macroblocks is 2, the macroblock configuration field is set to 0, and 6 bits are equally allocated to the length fields of the first and second macroblocks.

When the number of macroblocks is 3, the macroblock configuration field is set to 1, and 4 bits are equally allocated to the length fields of the first, second, and third macroblocks.

Accordingly, the number and length of macroblocks can be changed according to different ACK/NACK modes, thereby efficiently configuring ACK maps.

FIG. 13 illustrates the structure of an ACK map according to a fifth embodiment of the present invention.

According to the fifth embodiment of the present invention, when consecutive ACK block groups and consecutive NACK block groups alternate with each other, NACK macroblocks and ACK macroblocks are alternately set.

Four bits are allocated to the length fields of the ACK macroblock and the NACK macroblock respectively, and they are set alternately, thereby effectively configuring consecutive ACKs and NACKs.

FIG. 14 illustrates the structure of an ACK map according to a sixth embodiment of the present invention.

As shown here, the macroblock configuration field indicates the number of macroblocks.

Regardless of the macroblock configuration field, since the syntax of the ARQ feedback message shown in FIG. 8 has addressed cumulative ACK by the BSN, the first macroblock is NACKed, so the first macroblock is mapped to be NACKed.

The next macroblock flag field is allocated 1 bit, thereby indicating whether the following macroblock is ACK or NACK. Here, '0' indicates a NACKed macroblock, and '1' indicates an ACKed macroblock.

The structure of the ACK map illustrated in FIGS. 9 to 14 may be used for the ACK field of FIG. 8 . In other words, when ACK type=3 (cumulative macroblock ACK), by using the BSN information about the last BSN of the first cumulative ACK, the ACK maps of FIGS. The ACK types are the same, and overhead can be reduced by using the ACK maps of Figures 9 to 13.

The cumulative macroblock ACK type is defined as a new ACK type according to the embodiment of the present invention, but the existing cumulative ACK type (ACK type=1) can be defined similar to the cumulative macroblock ACK type according to the embodiment of the present invention .

FIG. 15 illustrates a method for generating a feedback message for ARQ according to an embodiment of the present invention.

In step S100, when the receiver receives the PDU corresponding to the MAC ARQ window and stores the PDU in the receive buffer, the ARQ transmitter sets the ACK type of the corresponding PDU to transmit the corresponding ARQ feedback message.

When the ACK type is set to cumulative macroblock ACK at step S110, the value of the first ACKed BSN in the received block is estimated at step S120. When the first ACKed BSN is not a cumulative macroblock ACK, normal ACK processing is performed. The first ACKed BSN corresponds to the last BSN of the first consecutive ACKed block.

When defining the BSN of the first ACKed block, the number of ACK images to be generated in the ARQ window is estimated at step S130. The number of ACK maps corresponds to the number of macroblocks of consecutively ACKed blocks in the ARQ window.

In step S140, the ARQ transmitter estimates the starting BSN of the ACK map. The starting BSN is estimated by sequentially detecting BSNs corresponding to ACKs after the first cumulative ACK.

In step S150, the ARQ transmitter estimates the length of the corresponding ACK map. The length of the corresponding ACK map indicates the total number of blocks counted from the first BSN to the last BSN in the corresponding ACK map. Map each length in binary code.

In step S160, an ACK map is generated based on the estimated value and mapped in the feedback message. Information on the ACKed blocks is included in the feedback message, and blocks not successfully received are defined as NACKed blocks.

The ARQ transmitter transmits a feedback message including the ACK map and the cumulative ACK to the transmitter for data transmission at step S170.

A process (not shown) may be included in the method of generating the feedback message of FIG. 15 to detect whether a channel for data retransmission is dedicated, and to set a CID value when there is no channel dedicated to the feedback message.

FIG. 16 illustrates a flowchart of a method for transmitting an ARQ feedback message according to another embodiment of the present invention.

Since descriptions of steps S100 to S120 are the same as those of FIG. 15 , their descriptions will be omitted. After step S120 in FIG. 16, a macroblock ACK map is generated.

In step S200, the number of macroblocks used in the macroblock ACK map is set. The number of macroblocks can be addressed in bits for mapping, or selected by various options.

Regarding setting the number of macroblocks, each macroblock may have a different bit value for the length of each macroblock.

The number of macroblocks may be set to be two or more, but for convenience of description, it is set as a first macroblock and a second macroblock.

In steps S210 and S220, macroblock types of the first and second macroblocks are set. The macroblock type determines whether to ACK or NACK the macroblock. The macroblock type may be set to correspond to a plurality of macroblocks by using an additional field, or may be set to alternate ACK or NACK according to a predetermined order. Additionally, macroblock flags can be used to determine the macroblock type for each macroblock.

The macroblock type of the first macroblock is set to NACK, and the macroblock type of the second macroblock is defined by using the macroblock flag.

The lengths of the first and second macroblocks are estimated and mapped. In steps S230 and S240, the number of bits allocated to indicate the lengths of the first and second macroblocks, respectively, may be changed according to the number of macroblocks.

In step S250, a macroblock ACK map is generated, and the macroblock ACK map includes information on the number of macroblocks, macroblock types, and macroblock lengths.

In step S250, when the macroblock ACK map is generated, the macroblock ACK map is sent as a feedback message together with the ACKed BSN estimated in step S120.

As described above, a method for transmitting a feedback message for ARQ is realized by using an ARQ transmitter and a buffer. In other words, according to an embodiment of the present invention, an ACK map and a macroblock ACK map are generated by using a regular cumulative ACK message of a block stored in a buffer and checking a bitmap after the last BSN of the block being ACKed. The configuration of conventional cumulative and selective ACK-enabled receivers can be applied to implement ACK mapping and macroblock ACK mapping, and the application will be understood by those skilled in the art.

A program including the functions described above is recorded in a readable recording medium for controlling the ARQ receiver.

According to the above configuration of the present invention, the onset of regular ARQ feedback messages is reduced while performing efficient packet retransmission requests.

While the invention has been described in connection with what are presently considered to be the most practical and preferred embodiments, it is to be understood that the invention is not limited to the disclosed embodiments, but on the contrary, it is intended to cover various modifications and variations encompassed within the spirit and scope of the appended claims Equivalent arrangement.

Claims (8)

1. A method for sending a feedback message for an automatic repeat request, comprising: An ACK type is recorded in the first field, where the ACK type indicates one of a selective ACK type, a cumulative ACK type, a cumulative-selective ACK type, and a cumulative macroblock ACK type; Estimate the last block sequence number of the successive blocks successfully received to record the last block sequence number in the second field; If the ACK type is a cumulative macroblock ACK type, record in the third field the type of the group of consecutive blocks received successfully or unsuccessfully after the last block sequence number; If the ACK type is a cumulative macroblock ACK type, estimating the length of the group to record the length of the group in the fourth field; and Feedback information including fields from the first field to the fourth field is sent. 2. A method for sending a feedback message for an automatic repeat request, comprising: An ACK type is recorded in the first field, wherein the ACK type indicates one of a selective ACK type, a cumulative ACK type, a cumulative-selective ACK type, and a cumulative macroblock ACK type, Estimate the last block sequence number of the successive blocks successfully received to record the last block sequence number in the second field; Estimate the number of ACK images to record the number of ACK images in the third field; If the ACK type is the cumulative macroblock ACK type, the type of the group of consecutive blocks that were successfully or unsuccessfully received after the last block sequence number is recorded in the fourth field of each ACK map, where the group's type indicates whether each group was successfully received; If the ACK type is the cumulative macroblock ACK type, then estimate the length of the group of each ACK map to record the length of the group in the fifth field of each ACK map; and Feedback information including fields from the first field to the fifth field is sent. 3. A method for sending a feedback message for an automatic repeat request, comprising: Record the ACK type in the first field; Estimate the last block sequence number of the successive blocks successfully received to record the last block sequence number in the second field; Estimate the number of groups of successive blocks received successfully or unsuccessfully after the last block sequence number to record information about the number of groups in the third field; Record the type of group in the fourth field, wherein the type of group indicates whether each group is received successfully; Estimate the length of the group to record the length of the group in the fifth field; and Feedback information including fields from the first field to the fifth field is sent. 4. The method of claim 3, wherein the ACK type indicates one of a selective ACK type, a cumulative ACK type, a cumulative-selective ACK type, and a cumulative macroblock ACK type, where the estimated number of groups includes the estimated number of groups if the ACK type is a cumulative macroblock ACK type, and where the type of record group includes the type of record group if the ACK type is a cumulative macroblock ACK type, Wherein if the ACK type is the cumulative macroblock ACK type, the length of the group of the type of the record group is estimated. 5. A method for sending a feedback message for an automatic repeat request, comprising: An ACK type is recorded in the first field, wherein the ACK type indicates one of a selective ACK type, a cumulative ACK type, a cumulative-selective ACK type, and a cumulative macroblock ACK type, Estimate the last block sequence number of the successive blocks successfully received to record the last block sequence number in the second field; Estimate the number of ACK images to record the number of ACK images in the third field; If the ACK type is cumulative macroblock ACK type, the number of groups of consecutive blocks that were successfully or unsuccessfully received after the last block sequence number is estimated to record information about each block in the fourth field of each ACK map Information about the group number of an ACK image; If the ACK type is a cumulative macroblock ACK type, record the group type of each ACK map in the fifth field of each ACK map, wherein the group type indicates whether each group is successfully received; If the ACK type is the cumulative macroblock ACK type, then estimate the length of the group of each ACK map to record the length of the group in the sixth field of each ACK map; and Feedback information including fields from the first field to the sixth field is transmitted. 6. A method for sending a feedback message for an automatic repeat request, comprising: An ACK type is recorded in the first field, where the ACK type indicates one of a selective ACK type, a cumulative ACK type, a cumulative-selective ACK type, and a cumulative macroblock ACK type; Estimate the last block sequence number of the successive blocks successfully received to record the last block sequence number in the second field; If the ACK type is cumulative macroblock ACK type, estimate the length of the group of consecutive blocks that are successfully or unsuccessfully received after the last block sequence number to record the length of the group used for ACK and the length of the group used for NACK the length of the group to record the length of the group in the third field; and Send feedback information including the first field to the third field. 7. A method for sending a feedback message for an automatic repeat request, comprising: An ACK type is recorded in the first field, wherein the ACK type indicates one of a selective ACK type, a cumulative ACK type, a cumulative-selective ACK type, and a cumulative macroblock ACK type, Estimate the last block sequence number of the successive blocks successfully received to record the last block sequence number in the second field; Estimate the number of ACK images to record the number of ACK images in the third field; If the ACK type is cumulative macroblock ACK type, estimate the length of the group of consecutive blocks that are successfully or unsuccessfully received after the last block sequence number to record the length of the group used for ACK and the length of the group used for NACK the group length to record the group length of each ACK map in the fourth field of each ACK map; and Feedback information including fields from the first field to the fourth field is sent. 8. A method for sending a feedback message for an automatic repeat request, comprising: An ACK type is recorded in the first field, where the ACK type indicates one of a selective ACK type, a cumulative ACK type, a cumulative-selective ACK type, and a cumulative macroblock ACK type; Estimate the last block sequence number of the successive blocks successfully received to record the last block sequence number in the second field; If the ACK type is the cumulative macroblock ACK type, estimate the number of groups of consecutive blocks received successfully or unsuccessfully after the last block sequence number, with information about the number of groups in the third field; If the ACK type is a cumulative macroblock ACK type, then estimate the length of the start group of the group to record the length of the start group in the fourth field; If the ACK type is a cumulative macroblock ACK type, record the type of the next group of the starting group in the fifth field; If the ACK type is a cumulative macroblock ACK type, then estimate the length of the next group to record the length of the next group in the sixth field; If the ACK type is a cumulative macroblock ACK type, record the type of the next group of the next group in the seventh field; and Feedback information including fields from the first field to the seventh field is transmitted.

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