KR20090039565A - Apparatus and method for transmitting/receiving feedback information in a communication system - Google Patents

Abstract

An apparatus and a method for transmitting/receiving the feedback information in a communication system are provided to simplify the total system and improve the whole communications system. A method for transmitting/receiving the feedback information in a communication system is as follows. The MS(Mobile Station) receives data from the BS(Base Station)(301). The MS inspects the error of the received data. The MS produces the ACK bit or the NACK bit(303). The MS produces the transmission symbol, when the sub carrier bundle 3 of 8x1 of ACK or NACK bit is arranged. If the MS recognizes that data were normally received, the pattern '0' is chosen and the transmission symbol is transmitted to the BS(305).

Description

Apparatus and method for transmitting and receiving feedback information in a communication system {APPARATUS AND METHOD FOR TRANSMITTING / RECEIVING FEEDBACK INFORMATION IN A COMMUNICATION SYSTEM}

The present invention relates to a communication system, and more particularly, to an apparatus and method for transmitting and receiving feedback information in a communication system.

The next generation communication system is evolving in the form of providing services capable of high-speed, high-capacity data transmission and reception to mobile stations (MSs).

The most fundamental problem in the next generation communication system is how efficiently and reliably data can be transmitted through a channel. The next generation communication system, which is being actively researched recently, requires a high speed communication system capable of processing and transmitting various information such as video and wireless data, beyond the initial voice-oriented service. Therefore, it is essential to increase the efficiency of the system by using a channel coding scheme suitable for the system.

In the next-generation communication system, when a transmitter, for example, a base station (BS), transmits data to an MS, due to noise, interference, fading, etc., depending on channel conditions, Inevitable errors occur and loss of information can occur. In general, in order to reduce the loss of information, various error-control schemes are used according to the characteristics of the channel to increase the reliability of the system. The most representative of these error control schemes is a hybrid automatic repeat request (HARQ) scheme (hereinafter, referred to as HARQ).

As the HARQ scheme is applied in the next generation communication system, the MS checks whether an error occurs with respect to the data received from the BS and feeds back the test result to the BS. For example, the BS transmits data to the MS. The MS receives the data and checks the data for errors. The MS then sends control information, i.e. a feedback message, to the BS in response to the check result. Herein, the feedback message may mean an ACK (ACKnowledgement) message or a NACK (Negative ACKnowledgement, hereinafter 'NACK') message.

That is, if the data is normally received, the MS sends an ACK message indicating the normal reception of the data to the BS. On the other hand, if the data is not received normally, the MS transmits a NACK message indicating the abnormal reception of the data to the BS.

As described above, in the next generation communication system, there is a separate physical channel for transmitting a feedback message transmitted from the MS to the BS, that is, control information such as ACK / NACK information. At this time, the information amount for transmitting the ACK information or NACK information is 1 bit, but is very important information for indicating whether or not the data error in the next-generation communication system.

Now, a method for transmitting and receiving an ACK / NACK message in a general communication system will be described with reference to the following equations.

First, when 3x3 subcarrier bundles are allocated to frequency-time base resources for transmitting an ACK / NACK message by the MS, the MS transmits whether the data received from the BS is an error through Equation 1 below. ACK / NACK message for, i.e., elements to be inserted into the transmission symbol are calculated.

는 n 번째 피드백 채널, 즉 ACK/NACK 채널의 k번째 부반송파의 전송 심벌을 나타낸다. 또한 상기

은 n번째 ACK/NACK 채널의 k번째 변조 심벌을 나타낸다. 상기 n은 ACK/NACK 채널의 인덱 스를 나타낸다. As shown in Equation 1,

Denotes a transmission symbol of the kth subcarrier of the nth feedback channel, that is, the ACK / NACK channel. Also above

Denotes the kth modulation symbol of the nth ACK / NACK channel. N represents the index of the ACK / NACK channel.

,

는 생략되어 전송될 수도 있다. 이 때, 상기 MS 의 변조기에서는 ACK을 나타내는 0 또는 NACK을 나타내는 1 중 어느 하나의 변조 패턴을 선택하여 변조 한다. 이는 하기 표 1과 같이 나타낼 수 있다.First, when the MS receives data from the BS, the MS checks whether the data is in error, and converts one of the feedback message, the ACK message, or the NACK message corresponding to the error into the form of Equation 1 below. Transmit to the BS. At this time, in the equation (1) is a phase change when k is 9 to 26

,

May be omitted and transmitted. At this time, the modulator of the MS selects and modulates any one of a modulation pattern of 0 representing ACK or 1 representing NACK. This can be represented as Table 1 below.

As shown in Table 1, when the data transmitted by the BS is normally received, the MS transmits a transmission symbol indicating a pattern '0' to the BS. Meanwhile, when the data transmitted by the BS is abnormally received, the MS transmits a transmission symbol indicating a pattern '1' to the BS. Here, since the transmission symbols are 3x3 pieces, the transmission symbols include 9 elements.

The demodulator of the BS that receives the feedback message using the modulation symbol of Equation 1 calculates the absolute value square of the correlation value for the modulation pattern for each of the 3x3 subcarrier bundles. Then, the sum of the squares of absolute values calculated corresponding to the modulation pattern is calculated, and the modulation pattern having the maximum value is recognized as the modulation pattern selected and transmitted by the MS. For example, if the maximum value calculated by the BS indicates a modulation pattern '0', the BS recognizes that the MS has transmitted an ACK message indicating that the data has been normally received. On the other hand, if the maximum value calculated by the BS indicates a modulation pattern '1', the BS recognizes that the MS has transmitted a NACK message indicating that the data has been abnormally received.

Secondly, if 3x3 subcarrier bundles are allocated to the frequency-time base resource for transmitting an ACK / NACK message, the MS transmits whether the data received from the BS is an error through Equation 2 below. Compute the elements to be inserted into the modulation symbol of the ACK / NACK message.

As shown in Equation 2, P0, P1, P2, and P3 represent QPSK modulation symbols. First, when the MS receives data from the BS, the MS checks whether the data is in error and sends a feedback message corresponding to the error, that is, one of an ACK message and a NACK message, as shown in Equation 2 below. Form to send to the BS. At this time, the modulator of the MS selects and modulates any one of a modulation pattern of 0 representing ACK or 1 representing NACK. This can be represented as Table 2 below.

As shown in Table 2, when the MS recognizes that the data transmitted by the BS is normally received, the MS transmits a transmission symbol indicating an ACK bit '0', for example, to the BS. In this case, the transmission symbol indicating the ACK bit '0' selects and transmits '0, 0, 0' among the vector indices shown in Table 3 below.

On the other hand, when the MS recognizes that the data transmitted by the BS is abnormally received, the MS transmits a transmission symbol indicating an ACK bit '1', for example, to the BS. In this case, the transmission symbol indicating the ACK bit '1' selects and transmits '4, 7, 2' among the vector indices shown in Table 3 below.

The demodulator of the BS that receives the feedback message using the modulation symbol of Equation 2 calculates the absolute value square of the correlation value for the modulation pattern for each of the 3x3 subcarrier bundles. Then, the sum of the squares of absolute values calculated corresponding to the modulation pattern is calculated, and the modulation pattern having the maximum value is recognized as the modulation pattern selected and transmitted by the MS. For example, if the maximum value calculated by the BS indicates a modulation pattern '0', the BS recognizes that the MS has transmitted an ACK message indicating that the data has been normally received. On the other hand, if the maximum value calculated by the BS indicates a modulation pattern '1', the BS recognizes that the MS has transmitted a NACK message indicating that the data has been abnormally received.

As described above, in order to transmit the feedback message including the ACK / NACK information, an orthogonal modulation method is conventionally used. Since the feedback message is transmitted using the orthogonal modulation scheme, a modulation pattern generated separately is used, and transmission symbols also use 9-PSK symbols, or a complex specific code word is generated and used. That is, the above complicated processes are required for the MS to transmit the feedback message, that is, the ACK / NACK message. Therefore, the BS that receives the ACK / NACK message also requires a complicated reception process.

The present invention proposes an apparatus and method for transmitting and receiving feedback information in a communication system.

The method proposed by the present invention is a method for transmitting feedback information by a mobile station in a communication system, the method comprising receiving data from a base station and checking whether the data is in error, and when the data is normally received as a result of the inspection. And transmitting a first message indicating that the data is normally received to the base station, wherein the first message is modulated using a first pattern indicating that the data is normally received.

Another method proposed by the present invention is a method for receiving feedback information from a base station in a communication system, the method comprising: transmitting data to a mobile station, receiving a feedback message for the transmitted data from the mobile station; And demodulating and decoding the demodulation and decoding method according to a preset demodulation and decoding scheme for the feedback message, and then recognizing that the feedback message includes a first pattern indicating that the mobile station has normally received the data.

The apparatus proposed in the present invention is a device for transmitting feedback information in a communication system, and receives data from a base station to check whether the data is in error, and when the data is normally received as a result of the check, And a mobile station which transmits a first message indicating that the reception was successful to the base station, wherein the first message is modulated using a first pattern indicating that the data has been received normally.

Another apparatus proposed by the present invention is a device for receiving feedback information in a communication system, the apparatus comprising: transmitting data to a mobile station, receiving a feedback message for the transmitted data from the mobile station, and presetting the feedback message. And demodulating and decoding corresponding to the demodulation and decoding scheme, the base station recognizing that the feedback message includes a first pattern indicating that the mobile station has normally received the data.

As described above, according to the present invention, when a mobile station transmits a feedback message, for example, an ACK or NACK message, in a HARQ-based communication system, the performance of the entire communication system is transmitted by using two modulation patterns in the message. This has the advantage of being simple to implement and simple to implement.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. In addition, in describing the present invention, when it is determined that a detailed description of a related known function or configuration may unnecessarily obscure the subject matter of the present invention, the detailed description thereof will be omitted.

The present invention proposes an apparatus and method for transmitting and receiving feedback information in a communication system.

Hereinafter, the present invention will be referred to as a transmitter, for example, a base station (BS) in a communication system to which a hybrid automatic repeat request (HARQ) scheme is applied. ) Transmits data to a mobile station (MS: Mobile Station, hereinafter referred to as 'MS'), the MS receives the data and checks whether the received data is in error. That is, when the MS transmits a feedback message, for example, an ACK message or a NACK message to the BS according to the error of the received data, an apparatus for efficiently transmitting and receiving the ACK / NACK message using frequency-timebase resources And a method.

Next, a structure of a transmitter, for example, an MS, in a communication system according to an embodiment of the present invention will be described with reference to FIG. 1.

1 is a diagram illustrating an MS structure in a communication system according to an exemplary embodiment of the present invention.

Referring to FIG. 1, the MS includes an encoder 101, a modulator 103, and an IFFT (Inverse Fast Fourier Transform, hereinafter referred to as IFFT) group 105. Upon receiving the data transmitted by the BS, the MS determines whether the data is in error and recognizes that an ACK message or a NACK message should be transmitted according to whether the data is in error. Accordingly, when an ACK bit or a NACK bit corresponding to an error of the data is generated, the encoder 101 encodes a codeword corresponding to the bit after encoding according to a preset coding scheme. 103).

The modulator 103 selects and modulates any one of modulation symbols preset in the codeword, and then generates and transmits a transmission symbol to the IFFT device 105. The IFFT unit 105 performs the IFFT on the transmission symbol and then transmits it to a receiver, that is, a BS.

Next, a structure of a BS in a communication system according to an exemplary embodiment of the present invention will be described with reference to FIG. 2.

2 is a diagram illustrating a BS structure in a communication system according to an embodiment of the present invention.

Referring to FIG. 2, the BS includes a fast fourier transform (FFT) group 201, a demodulator 203, and a decoder 205.

First, when receiving a feedback message from the MS, i.e., a transmission symbol corresponding to an error of data transmitted by the BS, the FFT unit 201 performs an FFT on the received symbol to the demodulator 203. Output The demodulator 203 demodulates in a manner corresponding to the modulation scheme performed by the MS and outputs the demodulator 205 to the decoder 205. At this time, the demodulation method calculates the dot product of the vector of the received symbol. The decoder 205 decodes in a manner corresponding to the coding scheme performed by the MS, determines which code word has been transmitted, that is, ACK or NACK, and then outputs a bit corresponding to the determination result. In this case, the decoding method sums the calculated inner products of the vectors, and then determines whether the ACK or the NACK is based on the sign of the inner products of the combined vectors.

Hereinafter, a method for transmitting and receiving an ACK / NACK message in a communication system according to an embodiment of the present invention will be described with reference to the equation.

When the frequency-time base resource for the MS to transmit an ACK or NACK message is allocated three 8x1 subcarrier bundle, ACK / to transmit the error of the data received from the BS by the following equation (3) Compute the NACK message, that is, the elements to be inserted into the transmission symbol.

As shown in Equation 3, the P0. P2 represents a QPSK modulation symbol. First, when the MS receives data from the BS, the MS checks whether the data is in error, and sends a feedback message corresponding to the error, that is, one of an ACK message and a NACK message, as shown in Equation 3 above. Form to send to the BS. At this time, the modulator 103 of the MS selects and modulates any one of a modulation pattern of 0 representing ACK or 1 representing NACK. This can be represented as Table 4 below.

As shown in Table 4, when the data transmitted by the BS is normally received, the MS transmits a transmission symbol indicating a pattern '0' to the BS. Meanwhile, when the data transmitted by the BS is abnormally received, the MS transmits a transmission symbol indicating a pattern '1' to the BS. In this case, since 8x1 transmission symbols are included, 8 elements are included.

In addition, since three 8x1 subcarrier bundles are allocated, one of modulation patterns of 0 representing ACK or 1 representing NACK may be selected and modulated as shown in Table 5 below.

As shown in Table 5, when the MS recognizes that the data transmitted by the BS is normally received, the MS transmits a transmission symbol indicating an ACK bit '0', for example, to the BS. In this case, the transmission symbol indicating the ACK bit '0' is repeated three times, that is, select '0, 0, 0' and transmit the pattern '0' shown in Table 4 above.

On the other hand, when the MS recognizes that the data transmitted by the BS is abnormally received, the MS transmits a transmission symbol indicating an ACK bit '1', for example, to the BS. In this case, the transmission symbol indicating the ACK bit '1' is repeated three times, that is, '1, 1, 1' is transmitted through the pattern '1' shown in Table 4 above.

The demodulator 203 of the BS receiving the feedback message using the modulation symbol of Equation 3 calculates a vector dot product for the two modulation patterns for each of the 8x1 subcarrier bundles. The decoder 205 of the BS then calculates the sum of the vector dot products of all possible modulation patterns for the code word, and then determines whether it is ACK or NACK using Equation 4 below.

As shown in Equation 4, Y denotes a reception signal in the frequency domain when the transmission signal S determined corresponding to ACK or NACK passes through the channel H. K is the number of 8x1 subcarrier bundles, and m represents the size of one subcarrier bundle. In Equation 4, if the value is less than 0, ACK is indicated, and when the value is 0 or more, NACK is indicated.

That is, the BS can determine whether the feedback message transmitted from the MS, that is, the transmission symbol is ACK or NACK, based on the value calculated through Equation 4.

Next, an MS operation in a communication system according to an exemplary embodiment of the present invention will be described with reference to FIG. 3.

3 is a diagram illustrating an MS operation in a communication system according to an exemplary embodiment of the present invention.

Referring to FIG. 3, in step 301, the MS receives data from the BS. The MS determines whether the data is normally received by checking whether the received data is in error. Then, in step 303, the MS generates an ACK bit or a NACK bit according to the determination result. At this time, when three 8x1 subcarrier bundles are allocated to the resource for transmitting the ACK or NACK bit, the MS generates a transmission symbol by using Equation (3). That is, when the MS recognizes that the data is normally received in step 305, the MS selects a pattern '0', generates a transmission symbol corresponding to the pattern '0', and transmits the same to the BS. If it is recognized that the data is abnormally received, a pattern '1' is selected to generate a transmission symbol corresponding to the pattern '1' and then transmitted to the BS.

In this case, since three 8x1 subcarrier bundles are allocated, the MS may transmit the ACK or NACK pattern according to Table 5 above.

Next, a BS operation in a communication system according to an exemplary embodiment of the present invention will be described with reference to FIG. 4.

4 is a diagram illustrating a BS operation in a communication system according to an exemplary embodiment of the present invention.

Referring to FIG. 4, in step 401, the BS receives a feedback message, that is, a transmission symbol from the MS, and proceeds to step 403. In step 403, the BS calculates a vector dot product for the received transmission symbol. That is, the BS calculates a vector dot product for two modulation patterns, that is, '0' or '1', for the three 8x1 subcarrier bundles. Then, the BS calculates the sum of the calculated vector dot products in step 405 and then determines whether it is ACK or NACK using Equation 4. At this time, when the value calculated in Equation 4 is less than 0, it is recognized that the MS has transmitted an ACK message indicating that the MS has normally received the data transmitted by the BS, and the calculated value is 0 or If more, the MS recognizes that the MS has transmitted a NACK message indicating that the BS abnormally received the data transmitted by the BS.

1 is a diagram illustrating an MS structure in a communication system according to an embodiment of the present invention.

2 is a diagram illustrating a BS structure in a communication system according to an embodiment of the present invention.

3 is a diagram illustrating an MS operation in a communication system according to an exemplary embodiment of the present invention.

4 is a diagram illustrating a BS operation in a communication system according to an embodiment of the present invention.

Claims (16)

A method for a mobile station to send feedback information in a communication system, the method comprising: Receiving data from a base station and checking whether the data is in error; If the data is normally received as a result of the inspection, transmitting a first message indicating that the data is normally received to the base station; And the first message is modulated using a first pattern indicating that the data is normally received. The method of claim 1, If it is determined that the data is not normally received, transmitting a second message to the base station indicating that the data is abnormally received. And the second message is modulated using a second pattern indicating that the data is abnormally received. The method of claim 1, And a first pattern indicating that the data is normally received indicates '0'. The method of claim 2, And a second pattern indicating that the data is abnormally received indicates '1'. In a communication system, a method in which a base station receives feedback information, Transmitting data to the mobile station; Receiving a feedback message for the transmitted data from the mobile station; A demodulation and decoding corresponding to a demodulation and decoding scheme preset for the feedback message, and then recognizing that the feedback message includes a first pattern indicating that the mobile station has normally received the data. How to receive information. The method of claim 5, A demodulation and decoding corresponding to a demodulation and decoding scheme set in advance for the feedback message, and then recognizing that the feedback message includes a second pattern indicating that the mobile station abnormally received the data. How to receive information. The method of claim 5, The process of recognizing that the first pattern indicating that the mobile station has normally received the data is included

The feedback information receiving method, characterized in that when the calculated value is less than zero. The method of claim 6, Recognizing that the second pattern indicating that the mobile station has normally received the data is included in the equation

The feedback information receiving method, characterized in that the case that is calculated to be 0 or more. An apparatus for transmitting feedback information in a communication system, And a mobile station receiving data from a base station to check whether the data is in error, and if the check result indicates that the data is normally received, transmitting a first message to the base station indicating that the data has been received normally. And a first message is modulated using a first pattern indicating that the data is normally received. The method of claim 9, When the mobile station does not receive the data normally as a result of the check, the mobile station transmits a second message to the base station indicating that the data is abnormally received, and the second message abnormally transmits the data. Feedback information transmitting apparatus, characterized in that modulated using a second pattern indicating that the received. The method of claim 9, And a first pattern indicating that the data is normally received indicates '0'. The method of claim 10, And a second pattern indicating that the data is abnormally received indicates “1”. An apparatus for receiving feedback information in a communication system, After transmitting data to the mobile station, receiving a feedback message for the transmitted data from the mobile station, and demodulating and decoding the demodulation and decoding scheme according to a preset demodulation and decoding scheme for the feedback message, the mobile station in the feedback message causes the mobile station to transmit the data. And a base station for recognizing that a first pattern indicating that data is normally received is included. The method of claim 13, The base station, after demodulating and decoding corresponding to a demodulation and decoding scheme preset for the feedback message, recognizes that the feedback message includes a second pattern indicating that the mobile station abnormally received the data. Feedback information receiving device characterized in that. The method of claim 13, Wherein the base station includes a first pattern indicating that the mobile station has normally received the data.

Feedback information receiving device characterized in that it is recognized when the calculated value is less than zero. The method of claim 14, Equation 2 includes a second pattern indicating that the mobile station has normally received the data.

Feedback information receiving device characterized in that the recognition if the value is calculated to be 0 or more.

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