KR100936609B1 - Method of Feedback Transmission and Adaptive Transmission in Radio Communication System - Google Patents

Abstract

The present invention relates to a feedback transmission and adaptive transmission method in a wireless communication system, and to reduce the amount of feedback while supporting the multi-band band-AMC mode and diversity mode, channel quality information feedback transmission that can increase the data transmission efficiency And an adaptive transmission method.

In the feedback transmission and adaptive transmission method according to the present invention, the user terminal derives the channel quality information from the received signal to select a subband to feed back the channel quality information, the user terminal according to whether the subband selection channel quality Feeding back the information to the base station, transmitting the adaptive transmission waveform according to the determined transmission mode by the base station determining the transmission mode based on the feedback channel quality information, and receiving the adaptive transmission waveform transmitted by the base station from the user terminal. Restoring the received waveform according to the determined transmission mode.

Wireless communication, feedback

Description

Feedback transmission and adaptive transmission method in wireless communication system {Method of Feedback Transmission and Adaptive Transmission in Radio Communication System}

The present invention relates to a feedback transmission and adaptive transmission method in a wireless communication system, and to a feedback transmission and adaptive transmission method that can improve data transmission performance without being affected by the number of user terminals.

The present invention is derived from the research conducted as part of the IT source technology development project of the Ministry of Information and Communication and the Ministry of Information and Telecommunications Research and Development. [Task Management Number: 2005-S-002-03, Title: Cognitive radio Technology development].

In next generation mobile communication, high speed and high quality data transmission is required to support various multimedia services with higher quality. As a technique for satisfying such a demand, research on the OFDMA method in the wireless communication system is active.

The OFDMA scheme is a multiple access scheme based on the OFDM scheme. The OFDM method is a method of transmitting data using a multi-carrier. A plurality of subcarriers having mutual orthogonality to each other by converting symbol strings serially input in parallel. In other words, it is a type of Multi Carrier Modulation (MCM) that modulates and transmits a plurality of sub-carrier channels.

The OFDMA scheme divides the subcarriers in one OFDM symbol by a plurality of users, that is, a plurality of subscriber stations.

In an OFDMA system, band-AMC and diversity mode transmission methods are mainly used as a method of adaptively transmitting data.

In the band-AMC mode, subcarriers in an entire band are divided into subbands formed by adjacent subcarriers, and a user terminal to transmit data and subbands to which the user terminal transmits data are selected using subchannel-specific channel quality information. Send data to In contrast, the diversity mode selects a terminal to transmit data using average channel quality information of all bands, and transmits data to any one subchannel among subchannels of distributed subcarriers.

Therefore, when band-AMC mode is applied, performance can be improved than diversity mode. However, since channel quality information for each subband is required, feedback channel capacity is larger than diversity mode requiring only channel quality information representing the entire band. need. Large feedback information results in low transmission efficiency.

Therefore, as a method for reducing the amount of feedback while reducing the performance reduction, a band-AMC mode is applied, and a method of feeding back only some subband indexes having good channel conditions among the subbands and only channel quality information of the subbands is proposed. However, in this method, when the number of user terminals is small, a subband without channel state information is generated, and there is an empty subband in which no data is transmitted, thereby lowering the data rate.

Alternatively, except for the selected subband, a user terminal may transmit an index of some subbands having good performance and channel quality information thereof, and may transmit the diversity mode to a user terminal having no subband selected. We proposed a method of transmitting average channel quality information for the remaining subbands. However, this method also has a disadvantage in that the amount of feedback increases linearly as the number of user terminals increases.

Accordingly, there is a need for an effective feedback transmission and adaptive transmission method that improves the data rate but is not affected by the number of user terminals.

The problem to be solved by the present invention, by selectively feeding back the sub-band channel quality information in the wireless communication system, and simultaneously support the band-AMC mode and diversity mode by time division or frequency division based on the sub band channel quality information To provide a feedback transmission and adaptive transmission method that can increase data transmission efficiency regardless of the number of user terminals.

The technical problems of the present invention are not limited to the technical problems mentioned above, and other technical problems not mentioned will be clearly understood by those skilled in the art from the following description.

According to an embodiment of the present invention, a feedback transmission and adaptive reception method of a user terminal for improving a transmission rate according to an embodiment of the present invention derives full band channel quality information and subband-specific channel quality information from a received signal, and based on a predetermined threshold value. Selecting a subband to which the channel quality information is fed back; and feeding back at least one channel quality information among the full band channel quality information and the subband channel quality information to a base station according to whether the subband is selected. And receiving an adaptive transmission waveform according to the transmission mode determined by the fed back channel quality information from the base station, and restoring the received waveform according to the determined transmission mode.

According to an aspect of the present invention, there is provided an adaptive transmission method of a base station for improving a transmission rate, the method comprising: receiving a feedback signal from a user terminal, detecting subband channel quality information from the feedback signal, and Determining a transmission mode of the user terminal based on the subband channel quality information, and generating and transmitting a transmission waveform according to the determined transmission mode.

According to the feedback transmission and adaptive transmission method in the wireless communication system according to the present invention, by selectively feeding back the sub-band channel quality information, and all the user terminals share a feedback channel, the feedback channel irrespective of the number of user terminals Do not increase the dose. In addition, by simultaneously supporting the band-AMC mode and the diversity mode based on the subband channel quality information by time division or frequency division, data transmission efficiency can be improved.

Hereinafter, a feedback transmission and adaptive transmission method in a wireless communication system according to the present invention will be described in detail with reference to the accompanying drawings.

The basic principle of the present invention is to selectively feedback subband channel quality information in a wireless communication system, for example, an OFDMA system, and time-division or frequency-division the band-AMC mode and diversity mode based on the subband channel quality information. By simultaneously supporting, the data transmission efficiency can be increased regardless of the number of user terminals.

1 is a diagram illustrating a frame structure used in a feedback transmission and an adaptive transmission method in an OFDMA system according to the present invention.

부반송파(1110)로 이루어진다.

부반송파(1110)에 해당하는 전체 밴드는 B 개의 부밴드(1210)로 이루어진다. 여기서, 한 부밴드(1210)는 OFDM 심볼(1100)당

부반송파(1110)로 이루어진다. 또한, 프레임(1000)은 다이버시티 모드(1300)와 밴드-AMC 모드(1400)를 시간 분할로 동시에 지원하는 프레임 구조를 갖는다. Referring to FIG. 1, one frame 1000 includes several OFDM symbols 1100. One OFDM symbol 1100

It consists of a subcarrier 1110.

The entire band corresponding to the subcarrier 1110 consists of B subbands 1210. Here, one subband 1210 per OFDM symbol 1100

It consists of a subcarrier 1110. In addition, the frame 1000 has a frame structure that simultaneously supports the diversity mode 1300 and the band-AMC mode 1400 in time division.

In the diversity mode 1300, the diversity mode subchannels 1310 and 1320 are made up of subcarriers 1110 dispersed in several subbands. In the band-AMC mode, the band-AMC mode subchannel 1410, 1420 is composed of adjacent subcarriers 1110 belonging to the same subband.

Hereinafter, a feedback transmission and adaptive transmission method for reducing the amount of feedback of channel quality information while supporting the user terminal in the appropriate transmission mode among the two transmission modes will be described.

2 is a flowchart of a feedback transmission and an adaptive transmission method according to the present invention.

Referring to FIG. 2, channel quality information for all bands and subbands is derived for each user terminal, and a feedback subband is selected based on a threshold value (S10).

Here, the overall band channel quality information may be represented by at least one of the overall band average SNR and the standard deviation. For example, the full band channel quality information may be an overall band average SNR value. It may also be represented using the overall band average SNR value and normalized standard deviation.

의 전체 밴드 평균 SNR 값은 부반송파별 SNR인

을

부반송파로 구성된 전체 밴드에 대해서 평균한 것으로 [수학식 1]에 의하여 나타낼 수 있다.User terminal

The overall band average SNR of is the subcarrier SNR.

of

The average of the entire band consisting of subcarriers can be represented by Equation 1.

[Equation 1]

In addition, the standard deviation can be represented by [Equation 2].

[Equation 2]

부밴드별 SNR 값일 수 있으며, [수학식 3]에 의하여 나타낼 수 있다.Channel quality information for each subband is determined for all subbands.

It may be an SNR value for each subband, and may be represented by Equation 3.

[Equation 3]

The user terminal feeds back channel quality information for each subband to the base station, but the feedback overhead is too large when feeding back all channel state information for each subband. Accordingly, the user terminal may select only the subbands that satisfy the condition where the subband SNR value is larger than the threshold value as shown in [Equation 4], and feed back only the channel quality information for the selected subband.

[Equation 4]

는

와 같이 모든 사용자 단말마다 동일한 상수를 사용할 수 있고, 사용자 단말마다

로 사용자 단말의 전체 밴드 SNR에 따라 다른 값으로 설정할 수 있다. 또한, 문턱 값

는 사용자 단말마다

로 사용자 단말의 전체 밴드 SNR 값과

에 따라 다른 값으로 설정할 수 있다. Where threshold

Is

Like the same constant can be used for all user terminals, and for each user terminal

This may be set to a different value according to the overall band SNR of the user terminal. Also, the threshold

Is for each user terminal

With the full band SNR value of the user terminal

It can be set differently depending on.

,

및

는 기지국이 셀 고유값으로 설정한 후, 사용자 단말로 브로드캐스팅할 수 있다. 여기서, 셀 고유값은 전체 시스템의 피드백 오버헤드와 성능을 함께 고려하여 설정될 수 있다.The parameter that determines this threshold,

,

And

After the base station is set to the cell unique value, it can be broadcast to the user terminal. Here, the cell eigenvalue may be set in consideration of the feedback overhead and the performance of the entire system.

In addition, the base station may variably change the parameter according to the number of user terminals transmitting feedback in the cell, and periodically broadcast the changed value.

When the user terminal selects a subband based on a threshold value, it is possible to limit the maximum number of subbands that can be selected for each user terminal, and information about this can be set at the time of initial installation of the system or broadcasted by the base station to the user terminal. have.

Subsequently, the user terminal transmits all band channel quality information and channel quality information of the selected subband (S20).

In detail, the user terminal feeds back only the full band channel quality information to the base station when there is no selected subband, and feeds back the selected subband channel quality information and all band channel quality information to the base station.

Here, the overall band channel quality information may be an overall band average SNR value. It may also include the overall band average SNR value and normalized standard deviation.

The subband channel quality information may include an index of a subband selected by a threshold value and an SNR value of the subband.

,

또는

의 문턱값을 더한 값일 수 있다.In addition, the user terminal may feed back only the selected subband index. In this case, the method of obtaining the SNR of the selected subband may be estimated by the threshold used when selecting the subband. For example, the SNR value of the selected subband is equal to the overall band average SNR value.

,

or

It may be a value obtained by adding a threshold value of.

Meanwhile, in a method of feeding back all band channel quality information and selected subband channel quality information, each piece of information may be transmitted in one region or may be transmitted in a different region to feed back. In addition, two transmission methods may be mixed and used according to arbitrary conditions.

When all band channel quality information and the selected subband channel quality information are fed back together in one region, a packet is formed by combining the bits corresponding to the two pieces of information and transmitted on the assigned feedback channel. In this case, the user terminal transmitting the feedback may be transmitted by a polling technique, an opportunistic technique, or a mixed method of polling and opportunistic techniques. The polling technique is a method of transmitting user terminals in turn, and the opportunistic technique is a method in which only user terminals selected by an arbitrary criterion are randomly transmitted with random probability.

In case of feeding back the full band channel quality information and the selected subband channel quality information into different areas, the full band channel quality information is an assigned feedback channel, and a polling technique, an opportunistic technique, or a mixing method of a polling technique and an opportunistic technique. In this case, a technique of transmitting opportunistic transmission while sharing multiple user terminals may be applied to an area for feeding back subchannel channel quality information.

에 따라, 전체 밴드 채널품질정보와 선택된 부밴드 채널품질정보를 한 영역 또는 다른 영역으로 분리하여 전송한다.In the case of feeding back a mixture of the two transmission methods, the threshold value of the number of user terminals and the number of terminals to which the channel quality information is fed back

In this case, the entire band channel quality information and the selected subband channel quality information are separated and transmitted to one area or another area.

보다 작으면, 전체 밴드 채널품질정보와 부밴드 채널품질정보를 한 영역의 피드백 채널로 전송한다.That is, the number of user terminals to which the channel quality information is fed back is a threshold of the number of terminals.

If smaller, all band channel quality information and subband channel quality information are transmitted to a feedback channel of one region.

보다 크면, 전체 밴드 채널품질정보와 부밴드 채널품질정보를 다른 영역의 피드백 채널로 전송한다.In addition, the number of user terminals to which the channel quality information is fed back is a threshold of the number of terminals.

If larger, the full band channel quality information and the subband channel quality information are transmitted to a feedback channel of another area.

가 단말 수의 문턱값

보다 작을 경우 부밴드 채널품질정보를 전송하는 영역의 낭비를 막기 위한 방법으로 효과적이다.This mixed transmission method is the number of user terminals

Threshold of the number of terminals

If smaller, it is effective as a method to prevent waste of the area for transmitting subband channel quality information.

FIG. 3 illustrates a method of transmitting an index of a selected subband when feedback of the entire band and subband channel quality information is divided into different areas and fed back.

(3410, 3420)을 전송하고, 선택되지 않은 부밴드에는 0을 전송한다. 따라서, 각 사용자 단말

가 전송하는 시간 영역에서의 OFDM 심볼은 [수학식 5]에 의하여 나타낼 수 있다.Referring to FIG. 3, a and b illustrate a method of transmitting indexes of selected subbands in each of user terminals 1 and 2. In the following description, a method of transmitting an index of a selected subband includes first transmitting an OFDM symbol in an area 3100 for feeding back subband channel quality information to a subband 3110 in the frequency domain in the same manner as a subband in a band-AMC mode. Divide. Subsequently, modulation sequences in which the SNRs 3110 and 3220 of the received signal are differently assigned to each user terminal only to the subbands 3111 and 3112 selected based on the threshold values 3310 and 3320 for each user terminal.

(3410, 3420), and transmits 0 to the unselected subbands. Thus, each user terminal

OFDM symbol in the time domain to be transmitted can be represented by Equation 5.

[Equation 5]

은 FFT 크기,

는 사용자 단말

가 선택한 부밴드 인덱스 집합,

는

이면 1이고

이면 0인 지시자이고,

는

보다 크지 않은 최대 정수를 의미한다.here,

Is the FFT size,

The user terminal

Sets of subband indices selected by

Is

Is 1

Is an indicator of zero,

Is

Means a maximum integer not greater than

 In this case, the time domain representation of the OFDM signal received in the region where the base station feeds back the subband channel quality information may be represented by Equation 6.

[Equation 6]

은 시간영역에서의 정규잡음 (AWGN),

은

번째 사용자 단말의

번째 부반송파에서의 채널주파수응답이고,

는 전체 채널품질정보를 피드백하는 사용자 단말의 수를 의미한다.here,

Is the normalized noise in the time domain (AWGN),

silver

Of the user terminal

The channel frequency response at the first subcarrier,

Denotes the number of user terminals that feed back the entire channel quality information.

2, the base station determines whether channel quality information is detected and whether subband channel quality information is present (S30).

Specifically, the base station detects the total band channel quality information and the different number of subband channel quality information for each user terminal, and determines the presence or absence of the subband channel quality information.

Here, the full band channel quality information demodulates a signal transmitted to the full band channel quality information feedback region to derive an average SNR value and a standard deviation.

The subband channel quality information may be derived according to the feedback information of the user terminal.

That is, when the user terminal feeds back the selected subband index and the SNR value of the subband, the user terminal demodulates the subband channel quality information.

However, when the user terminal feeds back only the index of the selected subband, the subband channel quality information is derived by estimating the SNR value of the corresponding subband using the threshold used when selecting the subband.

Hereinafter, when the full band channel quality information and the selected subband channel quality information are separated and fed back into different areas, the presence or absence of feedback of the subband channel quality information and a method of deriving the corresponding channel quality information will be described.

The base station transforms the received time domain OFDM signal into a frequency domain received symbol of Equation 7 by performing a fast fourier transform (FFT).

[Equation 7]

은

번째 부반송파에서의 정규잡음 (AWGN)을 의미한다.here,

silver

Mean Noise (AWGN) in the first subcarrier.

을 수신 심볼

과 부밴드별로 상관한 뒤 사용자 단말마다 변조 수열

을 전송한 부밴드 인덱스 집합

를 찾는다.Subsequently, the base station transmits the modulation sequence assigned to the k-th user terminal, that is, the user sequence, to obtain the subband index information transmitted by the k-th user terminal.

Receive symbol

Modulation sequence for each user terminal after correlating with each subband

Set of subband indices

Find it.

을 전송한 부밴드 인덱스 집합

는 각 부밴드의 수신 심볼을 [수학식 8]과 같이 사용자 단말 별로 사용자 수열로 상관한 후, 상관 출력

이 정보 검출 문턱값

보다 큰 부밴드의 집합일 수 있다.At this time, the modulation sequence for each user terminal

Set of subband indices

Correlates the received symbols of each subband in a user sequence for each user terminal as shown in [Equation 8], and then outputs a correlation

This information detection threshold

It may be a larger set of subbands.

는 기지국 가산 잡음 세기로 결정될 수 있다.Where the information detection threshold

May be determined as the base station added noise strength.

[Equation 8]

보다 클 때 효과적일 수 있다.In addition, the base station reduces the complexity of deriving the subband channel quality information, that is, the correlation output for each subband, when the user terminal feeds back channel state information, In addition, information indicating the presence or absence of channel quality information for each subband may be transmitted. Subsequently, when the information indicates the presence of the subband channel quality information, the base station detects whether the modulation sequence for the user terminal is transmitted for each subband only for the corresponding user terminal, thereby reducing the complexity of deriving the correlation output for each subband. Can be. In this method, the number of user terminals is a threshold value.

Can be effective when larger.

In transmitting information indicating the presence or absence of subband channel quality information, specifically, for example, information indicating the presence or absence of subband channel quality information may be set to one bit of 1 or 0 so that the base station can determine only transmission or not. have. As another method, information indicating the presence or absence of subband channel quality information may be defined as the number of subbands to be fed back, and the base station may select the subbands in ascending order of subband correlation by the number of subbands.

Meanwhile, as a method for more reliably detecting channel quality information for each subband in a base station, a method similar to a sequential interference cancellation technique may be applied.

That is, it detects the subband index transmitted with the modulation sequence in order of the user terminal having the largest band channel quality information, and after the detection, regenerates the signal of the corresponding user terminal and removes it from the received signal. A method of detecting a subband index.

를 검출한다. 이후, 사용자 단말의 신호 검출 후에 해당 사용자 단말의 신호를

를 다시 생성하여 [수학식7]의 주파수 영역 수신 신호에서 제거한다. 다음 사용자 단말의 부밴드 인덱스 검출시 이전에 검출된 사용자 단말에 대한 신호 간섭이 제거된 수신 신호로부터 검출할 수 있다. 즉, 전체 밴드 채널품질정보가 가장 큰 순으로 사용자 단말을 나열한 결과가

라고 가정한다. 여기서

는

째로 전체 밴드 채널품질정보가 큰 사용자 단말의 인덱스이다. 그러면, 전체 밴드 채널품질정보가

째로 큰 사용자 단말의 부밴드 인 덱스 집합

를 찾은 후, 수신 심볼에서

째 사용자 단말까지의 간섭 제거를 한 뒤의 수신 심볼은 [수학식9]에 의하여 나타낼 수 있다.Specifically, the subband index set in order of the user terminals having the largest band channel quality information.

Detect. Thereafter, after detecting the signal of the user terminal, the signal of the corresponding user terminal is

Regenerate and remove from the frequency-domain received signal of Equation (7). When the subband index of the next user terminal is detected, the detected signal interference with respect to the previously detected user terminal may be detected from the received signal. That is, the result of enumerating the user terminals in the order of the highest overall band channel quality information

Assume that here

Is

Secondly, the entire band channel quality information is an index of a large user terminal. Then, the overall band channel quality information

Subband Index Set of Second Largest User Terminal

After finding the, at the received symbol

The received symbol after removing interference to the user terminal may be represented by Equation (9).

[Equation 9]

는

째로 전체 밴드 채널품질정보가 큰 사용자 단말의 인덱스이다.here,

Is

Secondly, the entire band channel quality information is an index of a large user terminal.

을 얻음으로써, 해당 사용자 단말의 부밴드 인덱스를 검출할 수 있다.Then, using [Equation 9] as shown in [Equation 8] as the user sequence of the next user terminal outputs the correlation for each subband

By obtaining, the subband index of the user terminal can be detected.

Next, the base station determines the transmission mode of the user terminal (S40).

In detail, the base station selects a user terminal to transmit data based on the subband channel quality information among the user terminals having subband channel quality information and a subband to which the user terminal transmits data to determine the band-AMC mode. Also, among the user terminals having the subband channel quality information, the user terminal not determined in the band-AMC mode and the user terminal without the subband channel quality information are determined as the diversity mode.

Subsequently, the base station generates and transmits an adaptive transmission waveform based on the transmission mode (S50).

Specifically, a transmission waveform is generated and transmitted through some or all functions of an adaptive transmission scheme such as adaptive channel encoding and adaptive modulation, adaptive power amplification, adaptive OFDMA frame configuration, and adaptive subchannel mapping according to a transmission mode determined by a base station. .

For example, the user terminal processes the received waveform according to the transmission mode to restore information (S60).

In detail, the user terminal that has been allocated the resource recovers the received information by demodulating and decoding the transmitted waveform according to a transmission mode, that is, a band-AMC mode or a diversity mode.

As described above, in the feedback transmission and adaptive transmission method according to the present invention, by selectively feeding back the subband channel quality information, the feedback channel capacity may be increased according to the number of user terminals, and the band-AMC mode or The gain of diversity mode can be obtained together.

가 피드백 채널보다 작을 경우 부밴드 채널품질정보를 전송하는 영역의 이용 효율을 높이기 위한 방법으로, 부밴드별 SNR 값에 대한 정보를 전송할 때, 부밴드의 SNR의 범위를

(L은 2이상의 정수)레벨로 나눈 뒤, 사용자 단말마다

개의 다른 변조 수열을 SNR 레벨마다 할당하여 해당 부밴드에 전송할 수 있다. 즉, 사용자 단말과 SNR 값의 레벨마다 다른 변조 수열을 할당한다. 따라서, 한 사용자 단말은 여러 개의 다른 변조 수열로 구성된 변조 수열 집합을 사용할 수 있 고, 다른 사용자 단말과도 구별된 변조 수열 집합을 사용할 수 있다.In addition, in the feedback transmission and adaptive transmission method according to the present invention, the number of user terminals

Is smaller than the feedback channel to improve the utilization efficiency of the region transmitting the subband channel quality information. When transmitting information on the SNR value for each subband, the SNR range of the subband is determined.

(L is an integer of 2 or more) After dividing by the level, for each user terminal

Different modulation sequences may be allocated for each SNR level and transmitted to the corresponding subband. That is, different modulation sequences are allocated for each level of the user terminal and the SNR value. Therefore, one user terminal may use a modulation sequence set composed of several different modulation sequences, and may use a modulation sequence set that is also distinguished from other user terminals.

When a single threshold value is used for the received SNR of the user terminal when the number of user terminals is small, when the threshold value is high, the frequency of use of the area for transmitting the channel quality information decreases as the user terminal transmitting the channel quality information decreases. The allocation of user terminals to subbands is also lessened. On the other hand, when the threshold value corresponding to the SNR level is divided into a plurality of methods as described above, since the modulation sequence is transmitted based on the threshold value, the feedback information is increased and the allocation of the user terminal is increased accordingly.

Feedback transmission and adaptive transmission method in the OFDMA system according to the present invention can be implemented in the form of program instructions that can be executed by various computer means can be recorded on a computer readable medium. The computer readable medium may include program instructions, data files, data structures, etc. alone or in combination. Program instructions recorded on the media may be those specially designed and constructed for the purposes of the present invention, or they may be of the kind well-known and available to those having skill in the computer software arts. Examples of computer-readable recording media include magnetic media such as hard disks, floppy disks, and magnetic tape, optical media such as CD-ROMs, DVDs, and magnetic disks, such as floppy disks. Magneto-optical media, and hardware devices specifically configured to store and execute program instructions, such as ROM, RAM, flash memory, and the like. The medium may be a transmission medium such as an optical or metal wire, a waveguide, or the like including a carrier wave for transmitting a signal specifying a program command, a data structure, or the like. Examples of program instructions include machine code, such as that produced by a compiler, as well as high-level language code that can be executed by a computer using an interpreter. The hardware device described above may be configured to operate as one or more software modules to perform the operations of the present invention, and vice versa.

As described above, the present invention has been described by way of limited embodiments and drawings, but the present invention is not limited to the above embodiments, and those skilled in the art to which the present invention pertains various modifications and variations from such descriptions. This is possible.

Therefore, the scope of the present invention should not be limited to the described embodiments, but should be determined not only by the claims below but also by the equivalents of the claims.

1 is a diagram illustrating a frame structure used in a feedback transmission and an adaptive transmission method in an OFDMA system according to the present invention.

2 is a flowchart of a feedback transmission and an adaptive transmission method according to the present invention.

FIG. 3 illustrates a method of transmitting an index for a selected subband when feedback is performed by dividing all band and subband channel quality information into different areas.

Claims (17)

Deriving all band channel quality information and channel quality information for each subband from the received signal, and selecting a subband to which the channel quality information is fed back based on a predetermined threshold value; Feeding back at least one channel quality information of the full band channel quality information and the subband channel quality information to a base station according to whether the subband is selected; Receiving an adaptive transmission waveform corresponding to a transmission mode determined by the feedback channel quality information from the base station; And Restoring the received waveform according to the determined transmission mode. According to claim 1, The subband to feed back the channel quality information, Feedback transmission and adaptive reception method of the user terminal, characterized in that selected by a predetermined threshold set equally for each user terminal. According to claim 1, The subband to feed back the channel quality information, A feedback transmission and adaptive reception method of a user terminal, characterized in that each user terminal is set according to at least one of the full band average SNR and the standard deviation of the full band SNR. The method of claim 1, wherein in the feedback step, And if the subband to which the channel quality information is to be fed back is not selected, feeding back all band channel quality information. The method of claim 1, wherein in the feedback step, And if the subband to which the channel quality information is to be fed back is selected, feeding back all band channel quality information and subband channel quality information. The method of claim 5, The full band channel quality information is an average SNR of all bands. And the subband channel quality information is an index of a subband selected as subband channel quality information and an SNR of the subband. The method of claim 5, And feedbacking at least one of a full band average SNR and a standard deviation of the full band SNR as the full band channel quality information, and feeding back an index of a selected subband as the subband channel quality information. Receiving a feedback signal from a user terminal; Detecting subband channel quality information from the feedback signal; Determining a transmission mode of a user terminal based on the subband channel quality information; And Generating and transmitting a transmission waveform according to the determined transmission mode; Determining the transmission mode, Selecting a user terminal to transmit data based on the subband channel quality information among the user terminals fed back the subband channel quality information and a subband to which data is transmitted by the user terminal to determine a band-AMC mode; And Determining a diversity mode of a user terminal not fed back to the band-AMC mode and a user terminal not fed back the subband channel quality information to the diversity mode among the user terminals fed back the subband channel quality information; Adaptive transmission method of a base station comprising a. delete The method of claim 8, wherein in receiving the feedback signal, When only the index of the subband is fed back as the subband channel quality information, the subband SNR of the subband channel quality information is estimated as a standard band average SNR of the user terminal or a standard deviation of a threshold value and the full band SNR. step Adaptive transmission method of a base station comprising a. Deriving all band channel quality information and channel quality information for each subband, and selecting a subband to which the channel quality information is fed back; Dividing the feedback channel of the full band channel quality information and the subband channel quality information into different areas and allocating a specific modulation sequence to an area for transmitting the subband channel quality information; Feeding back the full band channel quality information and the subband channel quality information; Receiving an adaptive transmission waveform according to a transmission mode determined by the feedback channel quality information; And Restoring the received waveform according to the determined transmission mode. The method of claim 11, wherein And in the region for transmitting the full band channel quality information, an indicator indicating whether or not the subband channel quality information is transmitted together with the full band channel quality information. The method of claim 11, wherein When the number of user terminals is smaller than a feedback channel, the range of subband SNR, which is the subband channel quality information, is divided by an L level (L is an integer of 2 or more), and then L specific modulation sequences are divided according to the SNR level. Feedback transmission and adaptive reception method of a user terminal, characterized in that for transmitting to. Receiving a feedback signal from a user terminal, in which all band channel quality information and subband channel quality information are divided into different areas; Detecting subband channel quality information by correlating the subband channel quality information with a sequence assigned to a user terminal among the feedback signals; Determining a transmission mode of a user terminal based on the subband channel quality information; And And generating and transmitting a transmission waveform in accordance with the determined transmission mode. 15. The method of claim 14, wherein in the detecting of the subband channel quality information, The set of subbands in which the subband channel quality information is correlated for each subband and the correlated signal for each subband is larger than an information detection threshold means an index set of subbands in which a user equipment transmits a specific modulation sequence. Adaptive transmission method of the base station. 15. The method of claim 14, wherein in the detecting of the subband channel quality information, The subband index from which the specific modulation sequence is transmitted is detected by the first user terminal having the largest full band channel quality information from the subband channel quality information, and the subband from which the subband index of the first user terminal is removed. And a subband index of the second user terminal is sequentially detected from the channel quality information. The method of claim 14, When the indicator for the presence or absence of transmission of the subband channel quality information is fed back, the indicator is detected. Adaptive transmission method of a base station characterized by detecting the band channel quality information.

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