KR20060082016A - Apparatus and method for transmitting feedback information in a broadband wireless access communication system - Google Patents

Abstract

The present invention provides a method for efficiently transmitting various uplink FAST FEEDBACK information using a given frequency-timebase resource in a communication system based on Orthogonal Frequency Division Multiple Access (OFDMA).

The transmitting apparatus of the present invention is a terminal apparatus for transmitting feedback information on an uplink in a broadband wireless communication system, comprising: a controller configured to output 3 bits of information to be transmitted on the uplink in the broadband wireless communication system, and output from the controller; And a transmitter for coding, modulating and fast inverse Fourier transform.

Broadband Wireless Access System, MIMO, OFDMA, Mobile Internet, FAST FEEDBACK, Transmission Method

Description

Apparatus and method for transmitting feedback information in a broadband wireless access communication system {APPARATUS AND METHOD FOR TRANSMITTING FEEDBACK INFORMATION IN A BROADBAND WIRELESS ACCESS COMMUNICATION SYSTEM}

1 is a block diagram illustrating a part of a structure of a terminal transmitter for transmitting high speed feedback information on an uplink in an OFDMA-based broadband wireless access communication system;

2 is a block diagram of a base station receiver for receiving fast feedback information transmitted in an uplink in an OFDMA-based broadband wireless access communication system;

3 illustrates uplink fast feedback channels in an OFDMA-based broadband wireless access communication system;

4 is a diagram illustrating an allocation relationship on a frequency-time axis of a fast feedback channel for transmitting 3-bit information according to another embodiment of the present invention;

5 is a block diagram of a fast feedback information transmission using the DIUC scheme proposed in the present invention,

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

In general, a mobile communication system is evolving to provide a wireless packet data service based on a voice service. As a system capable of providing a wireless packet data service as described above, a third generation (hereinafter, referred to as "3G") mobile communication system has been developed to provide various multimedia services at high speed. However, in the 3G mobile communication system, users are classified using a code division multiple access (CDMA) method. The CDMA method is a method of transmitting data using different codes having orthogonality.

However, in the 3G system, there is a problem that high speed data cannot be provided at high quality due to lack of code. That is, because the code that can be used is limited, the problem is that the rate is limited. Accordingly, in order to solve this problem, researches and developers of mobile communication systems are considering a fourth generation (hereinafter referred to as "4G") broadband wireless access communication system called a next generation mobile communication system. The 4G communication system uses an orthogonal frequency division multiplexing (OFDM) scheme or an orthogonal frequency division multiple access (OFDMA) scheme for a base station and a mobile station. Transmit and receive data between (mobile stations). Since the OFDM or OFDMA scheme is used, the 4G communication system may increase the data rate to about 100 Mbps. Accordingly, the 4G communication system may provide services having various quality of service (hereinafter referred to as 'QoS').

As described above, the 4G communication system, that is, the broadband wireless access communication system, is developed in a form capable of transmitting and receiving data at high speed while ensuring mobility of a plurality of mobile stations. The broadband wireless access communication system transmits OFDM symbols using a time division scheme for data transmission. The OFDM symbol is transmitted divided into downlink and uplink. In addition, the downlink and uplink transmit OFDM symbols in specific slots, respectively. In this case, the specific slots are divided by time and frequency resources, respectively. In the broadband wireless communication system having such a configuration, physical channels having a special purpose in the uplink and the downlink respectively exist and transmit and receive signals.

Among the physical channels, there is an uplink fast feedback channel. The information included in the uplink fast feedback channel includes complete signal to noise ratio (hereinafter, referred to as 'S / N') information, differential S / N information for each band, and fast multi-input multiplexing. There is a variety of information, such as output Multiple Input Multiple Output (MIMO) feedback information, mode selection feedback information, MIMO feedback information, and the like. In this case, the complete S / N information means a signal-to-noise ratio for the entire band, that is, the entire frequency band. Since the fast feedback information of the uplink is very important for the operation of the communication system, high reliability in transmission should be ensured.

On the other hand, the conventional mobile station has transmitted 6 bits of information through one uplink channel in transmitting uplink high-speed feedback information. However, in case of using a single uplink channel and transmitting only fixed 6-bit information, a system requiring various feedback information, for example, a MIMO system having multiple antennas and requiring feedback information for each antenna or stream There is a lack of operational flexibility. This is because the multi-transmission antenna system requires information on various radio channels in order to obtain optimal performance while using a plurality of transmit antennas. Therefore, in the case of a multi-transmission antenna system, various feedback information is required according to the multi-antenna transmission algorithm. However, in the presently provided method, there is no way for the mobile station to feed back various feedback information. Accordingly, there is an urgent need for a method for efficiently feeding back feedback information in a communication system using multiple antennas.

Accordingly, an object of the present invention is to provide an apparatus and method for transmitting various feedback information on an uplink in a broadband wireless access communication system.

Another object of the present invention is to provide an apparatus and method for transmitting more fast feedback information on an uplink in a broadband wireless access communication system.

Another object of the present invention is to provide an apparatus and method capable of performing efficient communication through fast feedback information from various uplinks in a broadband wireless access communication system.

Another object of the present invention is to provide an apparatus and method for more accurately transmitting feedback information transmitted through an uplink in a broadband wireless access communication system.

Another object of the present invention is to provide an apparatus and method for securing flexibility of feedback information transmitted in an uplink in a broadband wireless access communication system.

A transmitting device of the present invention for achieving the above objects, as a terminal device for transmitting feedback information in the uplink in a broadband wireless communication system, configured to output the information to be transmitted in the uplink in the broadband wireless communication system in 3 bits And a transmitter for encoding, modulating and fast inverse Fourier transform the symbols output from the controller.

In addition, the reception apparatus of the present invention for achieving the above objects is a base station apparatus for receiving feedback information through an uplink fast feedback channel in a broadband wireless communication system, the fast Fourier symbols received through the uplink fast feedback channel The receiver converts, demodulates, decodes, and outputs the output signal, and receives the decoded information from the receiver to extract 3 bits of high speed feedback information or 6 bits of high speed feedback information. It includes a control unit for controlling.

In addition, the transmission method of the present invention for achieving the above object, as a method for transmitting feedback information on the uplink in the terminal of the broadband wireless communication system, by configuring the information to be transmitted on the uplink in the broadband wireless communication system by 3 bits Outputting and encoding, outputting a modulation, fast inverse Fourier transform, and transmitting the output symbols.

A receiving method of the present invention for achieving the above objects is a method for receiving feedback information through an uplink fast feedback channel in a base station apparatus of a broadband wireless communication system, the symbols received through the uplink fast feedback channel Fast Fourier transform, demodulate, decode and output, and receive the decoded information from the receiver to extract the 3 bit fast feedback information or 6 bit fast feedback information transmitted by the terminal, and through this Controlling the transmission.

The reception method of the present invention for achieving the above objects is a method for receiving information fed back from a mobile station performed by a base station in a broadband wireless access communication system, by using a specific modulation and coding scheme for the mobile station. And instructing to feed back channel information on the channel path, and performing data transmission next time in consideration of the fed back channel information.

A transmission method of the present invention for achieving the above objects, in a broadband wireless access communication system, a method for a mobile station to feed back channel information, using a specific modulation and coding scheme from a base station for a specific channel or a specific channel path And receiving feedback for feeding back channel information, and feeding back channel information to the base station according to the feedback information.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the following description of the present invention, if 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.

1 is a diagram schematically illustrating a structure of a transmitter for transmitting fast feedback information on an uplink in a broadband wireless access communication system to which an embodiment of the present invention is applied.

Referring to FIG. 1, first, an information data bit 100 to which a transmitter, that is, a mobile station, feeds back to a base station is input to an M-ary channel encoder 101. In this case, the M-ary channel encoder 101 performs channel encoding on the input information data bit 100 using an M-ary block code and a non-coherent modulator. Output to (103). The noncoherent modulator 103 inputs a coded word output from the M-ary channel encoder 101 and outputs a modulated symbol by applying a noncoherent modulation technique. In this case, the noncoherent modulator 103 may use an orthogonal modulation technique.

The modulated symbols output from the noncoherent modulator 103 are input to an Inverse Fast Fourier Transform (hereinafter referred to as an IFFT converter) 105. The IFFT converter 105 performs inverse fast Fourier transform on the input modulation symbols to generate an OFDM or OFDMA symbol for transmission.

Next, FIG. 2 will be described with reference to a receiver for receiving a symbol transmitted in the form shown in FIG.

2 is a diagram schematically illustrating a receiver structure for receiving fast feedback information in a broadband wireless access communication system to which an embodiment of the present invention is applied.

Referring to FIG. 2, the received signal 200 received by the base station from the mobile station through a wireless channel is input to a fast Fourier transform (hereinafter, referred to as an 'FFT converter') 201. The FFT converter 201 converts the input signal into fast Fourier transform, converts the signal into a frequency band signal, and outputs the signal to the noncoherent demodulator 203. The noncoherent demodulator 203 is input. The noncoherent demodulator 203 receives the symbols of the input frequency band and demodulates its soft decision value using a noncoherent demodulation method. The demodulated symbols are input back to the M-ary channel decoder 205. The M-ary channel decoder 205 receives the soft-determined value, determines and determines the transmitted codeword, and outputs a corresponding data bit. The information output as described above is high-speed feedback information transmitted by the mobile station if it is normally received without error in the transmission process or the demodulation and decoding process. Therefore, such fast feedback information is received by a controller provided in the base station or a scheduler provided in the base station, not shown in FIG. 2, and used for scheduling and information transmission at the next time point. Here, the controller (not shown in FIGS. 1 and 2) is included in a transmitter and a receiver, and the controller of the transmitter configures and outputs 3 bits or 6 bits of feedback information to be transmitted in uplink, and the receiver is in the uplink. The feedback information received through the link is extracted and transmission control is performed at the next time point information transmission.

Next, a method of transmitting uplink fast feedback information will be described.

3 illustrates an uplink fast feedback channel in a broadband wireless access communication system.

Referring to FIG. 3, reference numeral 300 of FIG. 3 represents subchannels in a specific time domain of the uplink. The subchannels together form at least one subcarrier. The portions 310, 320, 330, 340, 350, and 360 indicated by hatching in FIG. 3 illustrate tiles. Here, the tile includes 3 × 3 subcarriers. The six tiles 310, 320, 330, 340, 350, and 360 may be combined to form one fast feedback channel.

On the other hand, the information data bits fed back by the mobile station are input to the M-ary channel encoder 101 as described in FIG. Here, it is assumed that the information data bit is 6 bits, and that M = 8, that is, an 8-ary channel encoder is used. Therefore, as can be seen from the internal configuration of the reference numeral 330, information output from the 8-ary channel encoder is transmitted on eight subcarriers except 335 among the nine subcarriers of the reference numerals 331 to 339. A pilot subcarrier is carried on the 335 subcarriers.

Next, referring to Table 1 below, 64 possible codewords output from the 8-ary channel encoder will be described.

The 8-ary channel encoder is designed such that, for a given number and length of codewords, the minimum Hamming distance between codewords is maximum (eg, 5).

Next, referring to FIG. 1, the output of the M-ary channel encoder 101 encoder is input to the non-coherent modulator 103. The noncoherent modulator 103 uses an orthogonal modulation method. Table 2 shows orthogonal vectors to be used for orthogonal modulation, and orthogonal vectors to be used for each orthogonal modulation may be shown as in Equation 1 below.

Vector index Subcarrier modulation per codeword 0, subcarrier 1, ...,, subcarrier 7 0 P0, P1, P2, P3, P0, P1, P2, P3 One P0, P3, P2, P1, P0, P3, P2, P1 2 P0, P0, P1, P1, P2, P2, P3, P3 3 P0, P0, P3, P3, P2, P2, P1, P1 4 P0, P0, P0, P0, P0, P0, P0, P0 5 P0, P2, P0, P2, P0, P2, P0, P2 6 P0, P2, P0, P2, P2, P0, P2, P0 7 P0, P2, P2, P0, P2, P0, P0, P2

P0, P1, P2, and P3 in Table 2 are QPSK modulation symbols as shown in Equation 1.

A method of transmitting information data bits will be described using Table 1, Table 2, and Equation 1 above. First, if 6-bit information data to be transmitted is given, the codewords A0, A1, ..., A5 are determined according to Table 1. The first tile 310 is then an orthogonal vector corresponding to A0, the second tile 320 is an orthogonal vector corresponding to A1, the third tile 330 is an orthogonal vector corresponding to A2, and the fourth tile In Table 340, an orthogonal vector corresponding to A3 is applied, an orthogonal vector corresponding to A4 is applied to the fifth tile 340, and an orthogonal vector corresponding to A5 is finally applied to the sixth tile 360. Each method will be transmitted.

Next, the method at the time of reception is demonstrated. Upon reception, the noncoherent demodulator 203 of FIG. 2 described above first calculates the absolute square of the correlation value for eight possible orthogonal vectors for each of the six. The M-ary channel decoder 205 then calculates the sum of the squares of the absolute values of the correlation values of the orthogonal vectors for all 64 possible codewords, and then corresponds to the codeword having the maximum value among them. It is determined that the information data bit is transmitted.

Next, a method of transmitting 3 bits of feedback information applicable to a broadband wireless access communication system using multiple antennas will be described below.

4 is a diagram illustrating an allocation relationship on a frequency-time axis of a fast feedback channel for transmitting 3-bit feedback information in a broadband wireless access communication system according to an embodiment of the present invention.

Referring to FIG. 4, in the method of transmitting 3 bit feedback information, six tiles including 3 × 3 subcarriers constitute one uplink fast feedback channel. In addition, the 3-bit fast feedback channel proposed by the present invention divides one uplink fast feedback channel into two groups by dividing three odd-numbered tiles into one group or three even-numbered tiles into one group. It can be divided into a bit fast feedback channel. That is, reference numeral 400 is a diagram showing a set of subchannels in a specific time domain of the uplink. Therefore, a plurality of subchannels exist in the reference numeral 400. The even-numbered tiles 410, 420, 430 of the portions 410, 420, 430, 440, 450, and 460 indicated by hatching in FIG. 4 become one fast feedback channel according to the present invention, and are odd. The first tiles 440, 450, and 460 become another fast feedback channel. Therefore, according to the present invention, one fast feedback channel as shown in FIG. 3 may be divided into two fast feedback channels. The method of dividing the fast feedback channel is described in one embodiment, but in another method, three fast feedback subchannels may be configured using two tiles. Such modifications may be made on the basis of the general contents described in the specification of the present invention.

As described above, the 3-bit feedback information transmission method using one of the fast feedback channels may transmit a small amount of information such as an antenna group index, an antenna selection index, or a precoding index of a multiplex antenna (MIMO) technology. . In addition, the information data bits pass through the M-ary channel encoder 101 of FIG. 1 described above. In the case of the present invention, the number of information data bits is 3 bits, and M = 8, that is, an 8-ary channel encoder is used as in the other embodiment.

Table 3 below shows eight possible codewords output from an 8-ary channel encoder for 3-bit input information data provided by the present invention. The 8-ary channel encoder is designed such that a minimum Hamming distance between codewords is maximum (for example, 6) for a given number and length of codewords. The vector index of each codeword configured as described above is mapped to the corresponding allocation tile in the manner shown in Table 2, and transmitted in the same manner as in FIG. 1 described above.

FIG. 5 is a block diagram for transmitting fast feedback information using a downlink interval use code (DIUC) scheme proposed by the present invention.

Referring to FIG. 5, the above-described transmission method of FIG. 1 is designed to ensure stable reception quality of feedback information even in a poor wireless channel environment. Up to 6 bits of information can be transmitted. However, in order to efficiently increase cell capacity in a multi-transmission antenna system, as much radio channel information as necessary is required. Therefore, the 6-bit information is not enough. In order to provide as much information as possible in such a structure, there is a method of allocating a plurality of high-speed feedback channels capable of transmitting 6-bit feedback information, but there may be a problem of using a lot of resources in uplink.

Therefore, in order to solve such a problem, the present invention enables the mobile station having a good wireless channel environment to transmit a large number of feedback information bits by applying a transmission method for transmitting existing data as shown in FIG. Here, the fast feedback channel allocation is the same as the above-described scheme, but the actual transmission method uses a coding scheme and a modulation (QPSK, 16QAM, etc.) scheme previously promised between the system and the mobile station as the data. In addition, when the mobile station supports MIMO transmission, space-time coding such as space time block code (STBC) may be used to ensure more stable transmission in this DIUC scheme.

Next, a process of transmitting the 3 bit fast feedback information bit string 500 will be described. The fast feedback information bit string 500 uses a 3-bit fast feedback scheme proposed by the present invention, a Downlink Interval Usage Code (DIUC) scheme and the 6-bit fast feedback scheme described above. Can instruct the mobile station by transmitting a field as shown in Table 4 in downlink control information.

Here, when the CQICH type is '00', the mobile station feeds back channel quality information (hereinafter referred to as 'CQI') to the base station by using a 6-bit fast feedback scheme. A mobile station having a wireless channel environment uses a DIUC scheme for transmitting a lot of feedback information. In the case of '10', the mobile station transmits feedback information using even-numbered tiles allocated in the 3-bit fast feedback scheme. ', The mobile station transmits feedback information using odd-numbered tiles. Meanwhile, when the length of the CQICH field value is increased and information bits transmitted through the fast feedback channels are configured with fewer bits, the number of fast feedback channels may be further increased.

The fast feedback information bit string 500 is input to the encoder 501. The fast feedback information bit string 500 is an information bit string output from a controller not shown in FIG. The encoder 501 then encodes and outputs the information bit string according to the corresponding encoding method. Here, the encoder 501 may use coding methods using a convolutional turbo code, a convolutional code, or an STBC. The symbols encoded by the encoder 501 are modulated by the modulator 503 and output. The modulator 503 may be configured as a M order QAM modulator. The symbols modulated by the modulator 503 are inverse Fourier transformed by the fast inverse Fourier transformer 505 and converted into symbols to be transmitted.

Next, the DIUC method configuration method will be described in more detail.

The DIUC is used to distinguish the types of information elements of the DL-MAP message. For example, the DIUC may have a value of 0 to 15, and each DIUC value is a value to be used for a special purpose. Since the use of the DIUC is described in detail in the IEEE 802.16 standard document, the description thereof will be omitted.

In a first configuration method, the base station determines the modulation and coding scheme suitable for transmitting the CQI feedback information of the mobile station by using the strength of the received signal received from the mobile station or preset feedback information, and transmits the determined information to the mobile station. The mobile station uses the assigned feedback control channel and transmits the feedback information to the feedback control channel through the same mapping method as the data channel using the determined modulation and coding scheme. That is, in the case of the IEEE 802.16 specification, the same mapping scheme as the partial usage of subchannels (hereinafter, referred to as "PUSC") or the optional PUSC scheme is applied to the feedback control channel for transmission. However, if the wireless channel environment of the mobile station is worse than the required standard, the conventional feedback method (ie, CQICH type = 00 or 10 or 11) is used.

In this case, when the mobile station transmits feedback information using the DIUC method as compared to the feedback channel method capable of stable transmission, that is, the 3 or 6 bit transmission method, the amount of feedback information that can be transmitted may increase. However, since the same modulation and coding as the data is used, the reception performance of the base station cannot be guaranteed if the radio channel is not stable. Therefore, the transmission error of feedback information may degrade the whole system. In order to solve this problem, a method that can identify an error of DIUC transmission using cyclic redundancy checking (CRC) is used. That is, when a CRC error occurs in the feedback channel information, the base station ignores the received feedback information. In addition, when a plurality of CRC errors occur, the base station stops transmitting feedback information to the mobile station in a DIUC scheme and instructs feedback of feedback information using stable 3 bits or 6 bits.

In a second method, the base station can preset a fixed modulation and coding scheme and instruct the mobile station to minimize the amount of computation and time delay caused by determining an optimal modulation and coding scheme among various modulation and coding schemes. In other words, using the predetermined modulation and coding scheme, the base station or the mobile station can operate stably. That is, if the radio channel environment of a particular mobile station is good compared to the criteria required, the mobile station feeds back feedback information using the DIUC-CQI channel using a fixed modulation and coding scheme referred to from DIUC, Feedback information is fed back using existing 3 or 6 bit feedback method.

Hereinafter, the second method will be described in more detail.

As an example, assume that the DIUC value referred to uses a QPSK modulation scheme and uses a CTC or CC 1/2 coding scheme. In such a case, the feedback control channel can transmit 48 data tones, which means that the total amount of information that can be sent is 48 bits.

The base station uses a CRC 16-bit method as a method for checking an error of information fed back from the mobile station. Accordingly, when the total amount of information has 48 bits, 32 bits excluding the CRC 16 bits are the number of information bits actually transmitted. Table 5 below shows the 32-bit information that can be transmitted. Here, the first 3 bits indicate the feedback information mode to be transmitted. The next four bits represent the number of feedback data information units (4 or 5 bits). The following feedback data information field has 24 or 25 bits and transmits feedback data information corresponding to a mode. Here, the feedback data information has 4 or 5 bits in the basic unit, and the information of the basic unit is multiplied by N and transmitted. The maximum value of N is 6 in 4 bit units and 5 in 5 bit units.

Mode (3 bit) Number of feedback units (4 bits) Feedback data information 0b000 N Preferred B-AMC Band Index (5 bits) 5 * N bits total 0b001 N Measurement SNR of the selected B-AMC band (5-bit) Total 5 * N bits 0b010 N Measurement SNR of nth pilot pattern (5 bits) 5 * N bits total 0b011 N nth MIMO stream measurement SNR (5 bits) 5 * N bits total 0b100 N DIUC index (4 bits) for the nth MIMO stream, total 4 * N bits 0b101 N UIUC index (4 bits) for the nth MIMO stream, total 4 * N bits 0b110-111 Reserved

In Table 5, B-AMC means a band-adaptive modulation and coding (Band AMC) scheme. That is, the mobile station feeds back information on channel quality to the base station in a manner corresponding to the mode indicated by the base station. For example, in the mode 0b000, the mobile station may feed back the index information of the five preferred band AMCs among the plurality of band AMC subchannels to the base station. Of course, the mobile station may also feed back signal-to-noise ratio information for a predetermined number of Band AMC subchannels, as in other modes. The mobile station may also feed back index information or signal-to-noise ratio information for MIMO streams received in multiple paths using multiple antennas.

Meanwhile, in the detailed description of the present invention, specific embodiments have been described, but various modifications are possible without departing from the scope of the present invention. Therefore, the scope of the present invention should not be limited to the described embodiments, but should be defined not only by the scope of the following claims, but also by those equivalent to the scope of the claims.

As described above, in the broadband wireless access communication system, various schemes for configuring and transmitting high-speed feedback information can be provided. Accordingly, there is an advantage in that effective and accurate channel information can be fed back to a system using multiple antennas.

Claims (13)

A mobile station apparatus for transmitting feedback information on an uplink in a broadband wireless access communication system, A controller configured to output 3-bit information to be transmitted on the uplink in the broadband wireless communication system; And a transmitter for encoding, modulating and fast inverse Fourier transform the symbols output from the controller. A base station apparatus for receiving feedback information through an uplink high speed feedback channel in a broadband wireless communication system, A receiver for fast Fourier transforming, demodulating, decoding, and outputting symbols received through the uplink fast feedback channel; And a control unit which receives the decoded information from the receiver and extracts 3 bits of fast feedback information or 6 bits of fast feedback information transmitted by the terminal, and controls transmission of the next time point through this. A method for transmitting feedback information on an uplink in a terminal of a broadband wireless communication system, Outputting the 3-bit information to be transmitted on the uplink in the broadband wireless communication system; And encoding the output symbols, modulating and performing fast inverse Fourier transform. A method for receiving feedback information through an uplink high speed feedback channel in a base station apparatus of a broadband wireless communication system, Fast Fourier transforming, demodulating, decoding, and outputting symbols received through the uplink fast feedback channel; And receiving the decoded information from the receiver and extracting 3 bits of fast feedback information or 6 bits of fast feedback information transmitted by the terminal, and controlling the transmission of the next time point. A method for receiving information fed back from a mobile station performed by a base station in a broadband wireless access communication system, Instructing the mobile station to feed back channel information for a particular channel or a particular channel path using a particular modulation and coding scheme; The data transmission method is performed next considering the feedback channel information. The method of claim 5, The fed back channel information is a predetermined number of sub-channel band index information having good channel quality. The method of claim 5, The fed back channel information is channel quality information of a predetermined number of subchannel bands. The method of claim 7, wherein Wherein the channel quality information is signal to noise ratio information. The method of claim 5, The feedback channel information is characterized in that the quality information of the signals received through the multi-path. The method of claim 5, The channel quality information is characterized in that the index information of the signals received through the multi-path. The method of claim 5, The specific modulation and coding scheme is predetermined information between the mobile stations. The method of claim 5, Wherein the specific modulation and coding scheme is any one of a plurality of modulation and coding schemes determined according to channel conditions between the mobile stations. In a broadband wireless access communication system, a method for a mobile station to feed back channel information, Receiving instructions from the base station to feed back channel information for a specific channel or a specific channel path using a specific modulation and coding scheme; And feeding back channel information to the base station according to the feedback information.

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