KR101208545B1 - method of transmitting response signals for transmitted signals in communication system - Google Patents

Abstract

 The present invention relates to a method for transmitting a response signal at a receiving side, and more particularly, to a method for transmitting a response signal to a transmission signal in a communication system.

The present invention comprises the steps of: receiving a plurality of HARQ process blocks from at least one transmitting end to achieve the above object; Decrypting the HARQ process blocks and checking whether each block has been successfully received; Transmitting one response signal to the transmitting end when the test results for the plurality of HARQ process blocks are all the same; And transmitting a response signal for each of the plurality of HARQ process blocks to the transmitting end when there are different results among the test results for the plurality of HARQ process blocks.

HARQ, Group ACK, Group NACK, Multi, Response

Description

Method of transmitting response signals for transmitted signals in communication system

1 is a block diagram illustrating an operation principle of a stop-and-wait HARQ scheme.

2 is a block diagram illustrating the operation of an N-Channel Stop-and-wait HARQ scheme.

3 shows an operation when a plurality of HAQR process blocks are transmitted.

4A to 4C are block diagrams illustrating a method of constructing a response signal when it is determined that a reception success probability of data transmitted in a communication system is high.

5A to 5C are block diagrams illustrating a method of constructing a response signal when it is determined that the reception success probability of data transmitted in the communication system is low.

6 shows a transmission / reception operation when the probability of receiving data successfully is high.

7 illustrates a transmission / reception operation when the probability of success reception failure is high.

8 is a block diagram showing an example of a receiving side according to the present embodiment.

The present invention relates to a method for transmitting a response signal at a receiving side, and more particularly, to a method for transmitting a response signal to a transmission signal in a communication system.

Hereinafter, an error control algorithm used in a communication system to which the present invention is applied will be described.

Error control algorithms can be largely classified into two methods: automatic repeat request (ARQ) and forward error correction (FEC).

Types of ARQ include Stop and Wait ARQ, Go-Back-N ARQ, and Selective-Repeat ARQ.

The transmitting end according to the Stop and Wait ARQ technique confirms whether the received frame is correctly received each time (ACK signal confirmation) and then transmits the next frame.

The transmitting end according to the Go-Back-N ARQ technique transmits N consecutive data frames and, if the transmission is not successful, retransmits all data frames transmitted after the frame in which an error occurs.

The transmitting end according to the Selective-Repeat ARQ technique selectively retransmits only an error frame.

Hereinafter, a hybrid retransmission scheme combining a retransmission scheme and an error correction scheme will be described.

Hybrid Automatic Repeat reQuest (HARQ) is a technique that controls errors by combining retransmission and error correction. It has the feature of maximizing error correction code capability of data received during retransmission.

1 is a block diagram illustrating an operation principle of a stop-and-wait HARQ scheme. As shown in FIG. 1, the transmitting end Tx transmits a data block corresponding to the index '1', and the receiving end Rx receives the data block corresponding to the index '1' and then receives an ACK (ACKnowledgement). ) / NACK (No ACK) is determined, and the determination result is sent to the transmitting end. If the transmitting end Tx receives the NACK signal, the transmitting end transmits the data block corresponding to the index '1' to the receiving end again.

The technique shown in FIG. 1 is the simplest and most efficient transmission method. However, the link transmission efficiency decreases due to a rounding trip time (hereinafter, referred to as 'RTT') until the transmitting end transmits and receives the ACK / NACK from the receiving end of the data.

An improvement on the Stop-and-wait HARQ technique is the N-Channel Stop-and-wait HARQ technique.

2 is a block diagram illustrating the operation of an N-Channel Stop-and-wait HARQ scheme.

As illustrated, several (N) independent stop-and-wait HARQ schemes may be operated until ACK / NACK is exchanged.

The technique of FIG. 2 has an advantage of improving link transmission efficiency compared to the technique of FIG.

In general, in the Stop And Wait HARQ method, the receiving end checks whether data is successfully received through an error detection technique such as a cyclic redundancy check (CRC) or a parity check.

The data unit that an error can detect by various error detection techniques is called a HARQ process block.

If an error of data is not detected, the receiving end transmits an ACK signal, and if an error is detected, the receiving end transmits a NACK signal.

The transmitting end receiving the ACK signal then transmits the data. The data transmitting end receiving the NACK signal retransmits the corresponding data having an error. In this case, the retransmitted data may change the format of the retransmitted data according to the HARQ type.

Meanwhile, when the transmission bandwidth is wide or when data is transmitted using multiple antennas, a plurality of HARQ process blocks may be transmitted. That is, a plurality (m) of HARQ processing modules transmit m HARQ process blocks at the same time.

3 shows an operation when a plurality of HAQR process blocks are transmitted.

The receiving end receiving the plurality of blocks may transmit m ACK / NACK signals for m HARQ process blocks to the transmitting end.

In the prior art, as the number of HARQ process blocks transmitted in unit time increases, the resource for transmitting ACK / NACK increases linearly, resulting in an increase in overhead of the control signal, thereby lowering system efficiency.

The present invention has been proposed to solve the above-mentioned problems of the prior art, and an object of the present invention is to propose a communication method for reducing overhead caused by ACK / NACK transmission.

Summary of the Invention

The present invention comprises the steps of: receiving a plurality of HARQ process blocks from at least one transmitting end to achieve the above object; Decrypting the HARQ process blocks and checking whether each block has been successfully received; Transmitting one response signal to the transmitting end when the test results for the plurality of HARQ process blocks are all the same; And transmitting a response signal for each of the plurality of HARQ process blocks to the transmitting end when there are different results among the test results for the plurality of HARQ process blocks.

Preferably, if all of the plurality of received HARQ blocks are successfully received, only one group ACK may be transmitted.

Preferably, when a NACK occurs in a state in which it is determined to transmit a group ACK when all of the received plurality of HARQ process blocks are successfully received, a group NACK is transmitted and ACK / NACK for each of the plurality of HARQ process blocks. Send.

Preferably, when all of the plurality of received HARQ blocks fails to receive only one group NACK may be transmitted.

Preferably, when an ACK occurs in a state in which it is determined to transmit a group NACK when all of the received plurality of HARQ process blocks are abnormally received, a group ACK is transmitted and ACK / NACK for each of the plurality of HARQ process blocks. Is sent.

Invention Example

Specific operations, features, and effects of the present invention will be embodied by the embodiments of the present invention described below.

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

The present embodiment proposes a method of reducing the overhead of the ACK / NACK signal when transmitting a plurality of HARQ process blocks at the same time or when a plurality of ACK / NACK signals are transmitted at the same time.

As described above, the HARQ process represents a unit of data in which an error can be detected. The HARQ process may be classified according to a specific user, or may be distinguished according to each data stream transmitted to one user. In addition, in a communication system provided with a plurality of transmit antennas, the HARQ process may be divided according to each transmit antenna.

The plurality of HARQ processes may be coded by different channel coding methods or coded by the same channel coding method. If coded by the same channel coding method, each HARQ process block may be coded according to an arbitrary coding rate.

This embodiment is characterized by considering the probability of success and failure of transmission data according to the environment of the communication system. This embodiment has the feature of reducing the overhead of the ACK / NACK signal according to the communication system environment.

This embodiment proposes a group ACK / NACK signal and an ACK / NACK signal for each HARQ process block to transmit response signals for a plurality of HARQ process blocks transmitted through a specific time unit, frequency unit, or spatial unit. do.

That is, the group ACK / NACK signal is a response signal for the plurality of HARQ process blocks, and the ACK / NACK signal other than the group ACK / NACK signal is a response signal for each HARQ process block.

First, a case where the probability of successfully receiving data transmitted by the environment of the communication system is high will be described.

If the probability that the transmitted data is successfully received is higher than the probability of failure, that is, when the probability of occurrence of the ACK signal is high, if the decoding result of the plurality of HARQ process blocks is all ACK, sending a group ACK signal of one bit desirable. Sending an ACK for all of the plurality of HARQ process blocks increases overhead, so it is desirable to send a group ACK signal of one bit.

In this case, when NACK occurs in any one of the plurality of HARQ process blocks, it is more preferable to send an ACK / NACK signal for each HARQ process block together with the group NACK signal.

4A is a block diagram showing a method of constructing a response signal when it is determined that the reception success probability of data transmitted in the communication system is high.

As shown, when m HARQ process blocks are transmitted, if all m blocks are successfully received, only group ACK is transmitted to the transmitting end. However, if any one of the m HARQ process blocks is not successfully received, it is preferable to transmit the group NACK to the transmitting end and to transmit ACK / NACK information for each of the m HARQ process blocks.

Of course, the number of ACK / NACK information transmitted together with the group NACK is m-1 or less, transmitted only information on the HARQ process block in which ACK occurs, or information on the HARQ process block in which NACK occurs. Although only transmission may be performed, if the transmitting end does not acquire the ACK / NACK information, a lot of delay may occur in retransmission. Therefore, the number of ACK / NACK information transmitted together with the group NACK is more preferably m.

FIG. 4B is a block diagram illustrating a transmitting / receiving end that transmits and receives a plurality of HARQ process blocks based on FIG. 4A.

4B illustrates the operation of a transmitting and receiving end under the premise that the probability of successfully receiving a transmitted HARQ process block is high.

First, the transmitting end transmits a plurality of HARQ process blocks {a [0], b [0], ..., f [0], g [0]}. Each HARQ process block includes CRC bits to parity bits to enable error checking. When the receiving end performs an error check and generates ACK for all HARQ process blocks, the receiving end transmits a group ACK signal to the transmitting end.

The transmitting end receiving the group ACK signal transmits a plurality of HARQ process blocks {a [1], b [1], ..., f [1], g [1]} to be transmitted next. The receiving end receiving the error checks. If a NACK occurs for f [1] and g [1], the receiving end sends the group NACK signal and the ACK / NACK result for the process blocks from a [1] to g [1] to the transmitting end. Send.

The transmitting end transmits the next process block {a [2], b [2], ...} for the HARQ process block in which the ACK is received after receiving the response from the receiving end, and the HARQ in which the NACK is received. Retransmission can be performed for the process blocks {f [1], g [1]}.

The HARQ technique used in the present embodiment may be classified into an incremental redundancy (IR) technique and a case combining technique (CC).

The CC technique is a technique for retransmitting data used for initial transmission in a retransmitting transmitter. In this case, power control may be additionally performed during retransmission. When transmitting using the CC technique, {f [1], g [1]} indicated by the leader line 401 and {f [1], g [1]} indicated by the leader line 402 are the same data. Therefore, the receiving end combines {f [1], g [1]} 401 and {f [1], g [1]} 402 to increase the received signal to noise ratio (SNR) for data. The reception success rate can be improved.

The IR technique is a method of increasing reception success rate by transmitting a portion of encoded data that was not used for initial transmission to lower a code rate of data received at a receiving end. In case of performing channel coding at the transmitting end, {f [1], g [1]} (401) encoded at a relatively high code rate is transmitted first, and {f including a portion not used for the initial transmission. [1], g [1]} 402 can be used for retransmission.

4C is a block diagram illustrating another transmitting / receiving terminal that transmits and receives a plurality of HARQ process blocks based on FIG. 4A.

4c illustrates the operation of a transmitting and receiving end under the premise that the probability of successfully receiving a transmitted HARQ process block is high.

First, the transmitting end transmits a plurality of HARQ process blocks {a [0], b [0], ..., f [0], g [0]}. When the receiving end performs an error check and generates an ACK for all HARQ process blocks, the receiving end transmits a group ACK signal to the transmitting end.

The transmitting end receiving the group ACK signal transmits a plurality of HARQ process blocks {a [1], b [1], ..., f [1], g [1]} to be transmitted next. The receiving end receiving the error checks. If NACK occurs for f [1] and g [1], the receiving end transmits the group NACK signal and the ACK / NACK result for the process blocks from a [1] to g [1] to the transmitting end. do.

The transmitting end may perform retransmission only for the HARQ process blocks {f [1], g [1]} in which the NACK is received after receiving the response from the receiving end.

In the example of FIG. 4C, the above-described Incremental Redundancy (IR) technique and the CC (Chase Combining) technique may be used.

If the CC technique is used, {f [1], g [1]} indicated by the leader line 411 and {f [1], g [1]} indicated by the leader line 412 are the same data. Therefore, the receiving end combines {f [1], g [1]} 411 and {f [1], g [1]} 412 to increase the received signal to noise ratio (SNR) for data. The reception success rate can be improved.

If the IR technique is used, {f [1], g [1]} (411) encoded at a relatively high code rate is initially transmitted, and {f [1 including a portion not used for the initial transmission. ], g [1]} 412 can be used for retransmission.

When the transmitting end according to FIG. 4C receives the group ACK for {f [1], g [1]} 412, new HARQ process blocks {a [2], b [2], ..., f [2], g [2]} is transmitted.

Hereinafter, a case where the probability of successfully receiving data transmitted by the environment of the communication system is low will be described.

If the probability of failure of the transmission data is greater than the probability of success, a signal is sent according to a technique in which the technique of FIG. 4 is applied in reverse. That is, if all of the transmission HARQ process block data is NACK, it is preferable to send a group NACK signal of one bit. On the other hand, if any of the transmission HARQ process block data ACK occurs, it is preferable to send an ACK / NACK signal for each transmission HARQ process block data with the group ACK signal.

5A is a block diagram illustrating a method of constructing a response signal when it is determined that the reception success probability of data transmitted in the communication system is low.

As shown, when m HARQ process blocks are transmitted, if all m blocks do not receive successfully, only group NACK is transmitted to the transmitting end. However, if any one of the m HARQ process blocks is successfully received, it is preferable to transmit a group ACK to the transmitting end and to transmit ACK / NACK information for each of the m HARQ process blocks.

Of course, the number of ACK / NACK information transmitted together with the group ACK is m-1 or less, transmitted only information on the HARQ process block in which NACK occurs, or information on the HARQ process block in which ACK occurs Although only the transmission may be performed, if the transmitter does not acquire the ACK / NACK information, a lot of delay may occur in retransmission. Therefore, the number of ACK / NACK information transmitted together with the group NACK is more preferably m.

FIG. 5B is a block diagram illustrating a transmitting / receiving terminal that transmits and receives a plurality of HARQ process blocks based on FIG. 5A.

FIG. 5B shows the operation of the transmitting and receiving end under the premise that the probability of successfully receiving the transmitted HARQ process block is low.

First, the transmitting end transmits a plurality of HARQ process blocks {a [0], b [0], ..., f [0], g [0]}. Each HARQ process block includes CRC bits to parity bits to enable error checking. When the receiving end performs an error check and generates NACK for all HARQ process blocks, the receiving end transmits a group NACK signal to the transmitting end.

The transmitting end receiving the group NACK signal retransmits a plurality of HARQ process blocks {a [0], b [0], ..., f [0], g [0]}. The receiving end receiving the error checks. If NACK occurs in f [0] and g [0], the receiving end transmits the group ACK signal and the ACK / NACK result for the process blocks from a [0] to g [0] to the transmitting end. do.

The transmitting end transmits the next process block {a [1], b [1], ...} for the HARQ process block in which the ACK is received after receiving the response from the receiving end, and the HARQ in which the NACK is received. Retransmission may be performed for the process blocks {f [0], g [0]}.

The CC technique may be applied to the example of FIG. 5B. In this case, power control may be additionally performed during retransmission. When transmitting using the CC technique, {f [0], g [0]} indicated by the leader line 501 and {f [0], g [0]} indicated by the leader line 502 are the same data. Therefore, the receiving end combines {f [0], g [0]} (501) and {f [0], g [0]} (502) to increase the received signal to noise ratio (SNR) for data. The reception success rate can be improved.

The IR technique can be applied to the example of FIG. 5B. In case of performing channel coding at the transmitting end, {f [0], g [0]} (501) encoded at a relatively high code rate is transmitted first, and {f including a portion not used for the first transmission. [0], g [0]} 502 can be used for retransmission.

FIG. 5C is a block diagram illustrating another transmitting / receiving terminal that transmits and receives a plurality of HARQ process blocks based on FIG. 5A.

5c illustrates the operation of the transmitting and receiving end under the premise that the probability of successfully receiving the transmitted HARQ process block is low.

First, the transmitting end transmits a plurality of HARQ process blocks {a [0], b [0], ..., f [0], g [0]}. When the receiving end performs an error check and generates NACK for all HARQ process blocks, the receiving end transmits a group NACK signal to the transmitting end.

The transmitting end receiving the group NACK signal retransmits a plurality of HARQ process blocks {a [0], b [0], ..., f [0], g [0]}. The receiving end receiving the error checks. If NACK occurs for f [0] and g [0], the receiving end transmits the group ACK signal and the ACK / NACK result for the process blocks of a [0] to g [0] to the transmitting end. do.

The transmitting end may perform retransmission only for HARQ process blocks {f [0], g [0]} in which a NACK is received after receiving a response from the receiving end.

In the example of FIG. 5C, the above-described Incremental Redundancy (IR) technique and the CC (Chase Combining) technique may be used.

If the CC technique is used, {f [0], g [0]} indicated by the leader line 511 and {f [0], g [0]} indicated by the leader line 512 are the same data. Therefore, the receiving end combines {f [0], g [0]} (511) and {f [0], g [0]} (512) to increase the received signal to noise ratio (SNR) for data. The reception success rate can be improved.

If the IR technique is used, {f [0], g [0]} (512) encoded with a relatively high code rate is transmitted first, and {f [0 including the unused portion of the initial transmission. ], g [0]} 511 can be used for retransmission.

FIG. 6 shows a transmission / reception operation when the probability of successful data reception is high, and FIG. 7 shows a transmission / reception operation when the probability of successful reception is high.

In FIG. 6, the probability that data is successfully transmitted is referred to as p, and when m HARQ process blocks occur simultaneously, the number of bits required for the ACK signal and the NACK signal is as follows.

Meanwhile, in FIG. 7, the probability that data is successfully transmitted is referred to as q, and when m HARQ process blocks are generated at the same time, the number of bits required for the ACK signal and the NACK signal is as follows.

Hereinafter, a technique of adaptively operating the method of FIG. 4 and the method of FIG. 5 will be described.

The receiving side (for example, the mobile terminal or the base station) according to the present embodiment may examine the communication environment and determine that the transmission probability of the data is high or low. For example, when the state of the channel is greater than or equal to the first predetermined threshold, it is determined that the probability of successful data transmission is high, and the communication is performed using the method of FIG. It may be determined that the transmission success probability is low, and thus communication may be performed using the method of FIG. 5. The first threshold value and the second threshold value may be equal to or different from each other.

The high and low transmission probability of the data may be determined based on a carrier to interference and noise ratio (CINR) value or based on a received signal strength indicator (RSSI) value.

In addition, the reception side may determine whether the data transmission success probability is high or low, and may inform the reception side of the determined information.

8 is a block diagram showing an example of a receiving side according to the present embodiment.

As shown, the receiving side according to the present embodiment includes a transmission / reception module 120 for processing the reception signal 200 and the transmission signal 300. The output of the transmit / receive module 120 is processed by the demultiplexing module 130, the demodulation module 140, and the decoding module 150. The group ACK / NAK control unit 110 may control the transmission / reception module 120 to measure the state of the channel. Through this, it may be determined whether the current probability of successful data transmission is high or low. That is, the group ACK / NAK controller 110 may communicate with each other according to the method of FIG. 4 or 5. The group ACK / NAK controller 110 generates a group ACK / NAK according to the method of FIG. 4 or 5. The generated group ACK / NACK is processed through the encoding module 180, the modulation module 170, and the multiplexing module 160, and transmitted to the transmitting side by the transmitting / receiving module 120.

9 is a block diagram showing still another example of the receiving side according to the present embodiment.

9 illustrates channel information included in the received signal 200. Based on the obtained information, the group ACK / NAK controller 110 determines whether to use the method of FIG. 4 or the method of FIG. 5.

Table 1 shows the average number of bits of multiple ACK / NACK signals using the proposed multiple ACK / NACK transmission method given a number of m HARQ process blocks and the success (failure) probability p (q) of transmission data.

The number of bits of the existing multiple ACK / NACK signal is equal to the number of m, and the number of bits of the proposed multiple ACK / NACK signal is calculated according to Equations 1 and 2

m (the number of multi HARQ processes per packet) 2 3 4 5 10 20 p (q)
(the probability of success (fail) transmission) 0.7 2.02 2.97 4.04 5.16 10.72 20.98 0.8 1.72 2.46 3.36 4.37 9.93 20.77 0.9 1.38 1.8 2.38 3.05 es7.51 18.57 0.99 1.04 1.09 1.16 1.25 1.96 4.64

As shown in Table 1, when the probability of success of the transmission data is higher than 0.7, the proposed method can significantly reduce the overhead required.

It will be apparent to those skilled in the art that the present invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. Accordingly, the above detailed description should not be construed as limiting in all aspects and should be considered as illustrative. The scope of the invention should be determined by reasonable interpretation of the appended claims, and all changes within the equivalent scope of the invention are included in the scope of the invention.

Hereinafter, the effect of the present invention will be described.

The present invention has the effect of reducing the overhead according to ACK / NACK when a plurality of data is processed.

Claims (10)

In the wireless communication system, a receiving end transmits a response signal, Receiving a plurality of HARQ process blocks from at least one transmitting end; Decoding the plurality of HARQ process blocks and checking whether each block has been successfully received; And If a result of the check for each of the plurality of HARQ process blocks is the same, a response signal is transmitted to the at least one transmitting end, and if there are different results among the check results for each of the plurality of HARQ process blocks, Transmitting a response signal for each of the plurality of HARQ process blocks to the at least one transmitting end. The method of claim 1, If it is determined to transmit a group ACK signal when all of the received plurality of HARQ process blocks are successfully received, The one response signal is characterized in that the group ACK signal, the transmission method of the response signal. The method of claim 1, If it is determined to transmit a group NACK signal when all of the received plurality of HARQ process blocks are not successfully received, And the one response signal is the group NACK signal. The method of claim 2 or 3, And determining whether the one response signal is a group ACK or a group NACK signal when all of the test results for each of the plurality of HARQ process blocks are the same. The method of claim 1, The response signal transmitted when there are different results among check results for each of the plurality of HARQ process blocks is an ACK or NACK signal for each of the plurality of HARQ process blocks. Way. In the receiving end for transmitting a response signal in a wireless communication system, A transceiver module for receiving a plurality of HARQ process blocks from at least one transmitting end; And And a controller for decoding the plurality of HARQ process blocks and checking whether each block has been successfully received. The control unit, If the check result for each of the plurality of HARQ process blocks are all the same, the transmission and reception module controls to transmit one response signal to the at least one transmitting end, When there is a different result among the check results for each of the plurality of HARQ process blocks, the transmission and reception module controls to transmit a response signal for each of the plurality of HARQ process blocks to the at least one transmitting end. To the receiving end. delete delete delete delete

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