KR101343056B1 - Apparatus and method for allocating sub-channel in a orthogonal frequency division multiplexingaccess system - Google Patents

Abstract

The present invention relates to an apparatus and a method for allocating subchannels in an orthogonal frequency division multiple access system. The present invention relates to a preamble subchannel in consideration of each carrier in cluster set using a preamble of a received signal. And a terminal that feeds back the number of carrier groups considered when generating a preamble subchannel having the highest performance among the configured preamble subchannels and the number of carrier groups feedbacked from the most terminals. In addition to the base station constituting the channel by configuring and assigning the sub-channel to adapt to the channel state has the effect of improving the performance of the system.

Orthogonal Frequency Division Multiple Access System, OFDM, Subchannel, Subcarrier, FUSC, Diversity

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a subchannel allocating apparatus and method in an orthogonal frequency division multiple access (OFDMA) system,

The present invention relates to an apparatus and method for allocating subchannels in an Orthogonal Frequency Division Multiple Access (OFDMA) system, and more particularly, to configure a subchannel in consideration of a carrier in cluster fed back from a terminal. The present invention relates to a subchannel allocation apparatus and method for configuring a subchannel by selecting adjacent subcarriers by the number of carrier groups.

In a 4G (4th Generation) communication system, which is a next generation communication system, services having a variety of high-speed and various Quality of Service (hereinafter referred to as 'QoS') are provided to users Active research is underway. In particular, in the current 4G communication system, a wireless local area network (LAN) system and a wireless metropolitan area network (MAN) system are called. Researches are being actively conducted to support high-speed services in a form of guaranteeing mobility and quality of service (QoS) in a broadband wireless access communication system, such as the IEEE. Electrical and Electronics Engineers) 802.16a / d communication system and IEEE 802.16e communication system.

The IEEE 802.16 communication system is divided into the Orthogonal Frequency Division Multiplexing (OFDM) / Orthogonal Frequency Division Multiplexing (OFDM) to support a broadband transmission network on a physical channel of the wireless communication system, (Orthogonal Frequency Division Multiple Access (OFDMA) scheme).

The IEEE 802.16 communication system supports a diversity channel and an adaptive modulation and coding (AMC) channel. The diversity channel is a channel for preventing deterioration in reception performance of a specific terminal by distributing and transmitting a signal transmitted to one terminal in an arbitrary frequency band. In addition, the MC channel is a channel for communicating with the terminal through a frequency band preferred by the terminal.

Currently, the IEEE 802.16 communication system supports both diversity channel allocation and AMC channel allocation as a subchannel allocation method. Diversity channel allocation and MC channel allocation show different performance according to channel change. Diversity channel generally shows high performance at high speed, and MC channel allocation shows high performance at low speed.

Next, full usage of subchannels (FUSC), which is one of diversity channel allocation schemes, will be described below with reference to FIG. 1. 1 is a diagram illustrating a method of configuring a subchannel using FUSC in an orthogonal frequency division multiple access system according to the prior art.

Referring to FIG. 1, among the subcarriers constituting one OFDM symbol, the remaining data subcarriers except the guard band and the DC carrier are sequentially numbered. The data subcarriers are divided into groups of constant size. In addition, the one subchannel is formed by taking out one subcarrier from each group. The other subchannel is configured by applying the same method to the above from the remaining subcarriers except for the subcarriers used in the above-described subchannel.

However, configuring various channel changes only with the diversity channel and the MC channel may be a limitation in performance improvement. Accordingly, there is a need for a subchannel allocation apparatus and method for actively configuring a channel according to a channel change.

SUMMARY OF THE INVENTION An object of the present invention is to provide a subchannel allocation apparatus and method in an orthogonal frequency division multiple access system.

Another object of the present invention is to provide an allocation apparatus and method by configuring a subchannel adaptively to a channel change in an orthogonal frequency division multiple access system.

Another object of the present invention is to provide a terminal apparatus and a method thereof for calculating and requesting the number of carrier sets to be allocated a subchannel configured in consideration of a channel change in an orthogonal frequency division multiple access system.

Another object of the present invention is to provide a base station apparatus and method for configuring and allocating subchannels in consideration of channel changes in an orthogonal frequency division multiple access system.

Another object of the present invention is to select a subchannel by selecting adjacent subcarriers by the number of carrier groups when configuring a subchannel in consideration of the carrier in cluster requested by most terminals in an orthogonal frequency division multiple access system. An apparatus and method for allocating subchannels to constitute a subchannel are provided.

According to a first aspect of the present invention for achieving the above objects, the subchannel allocation apparatus in the orthogonal frequency division multiple access system, the carrier number in each carrier set using the preamble of the received signal (Carrier in Cluster) In the preamble subchannel configuration, the terminal that feeds back the number of carrier groups considered when generating the preamble subchannel having the highest performance among the preamble subchannels configured, It is characterized in that it comprises a base station constituting a sub-channel in consideration of the number of carrier groups fed back.

According to a second aspect of the present invention for achieving the above objects, a subchannel allocation apparatus in a terminal of an orthogonal frequency division multiple access system includes: a subcarrier demapping unit for extracting preamble subcarriers from received data, and the extracted preamble A CINR measuring unit measuring a carrier-to-interference plus noise ratio (CINR) of subcarriers, and a preamble subchannel considering carrier carriers using the preamble subcarriers Configure each carrier group number, measure the CINR variance of each preamble subchannel using the CINR value of the preamble subcarriers, and check the number of carrier groups considered when configuring the preamble subchannel with the smallest CINR variance. It characterized in that it comprises a carrier group number meter for feeding back to the base station (Feedback).

According to a third aspect of the present invention for achieving the above objects, the subchannel allocation apparatus in the base station of the orthogonal frequency division multiple access system receives the number of respective carrier groups fed back by each terminal, A carrier group estimator for identifying a carrier in cluster fed back from a terminal, and a sub-channel configurator for configuring a subchannel in consideration of the number of carrier groups fed back from the most terminals identified by the carrier group estimator; It is characterized by.

According to a fourth aspect of the present invention for achieving the above objects, a subchannel allocation method in an orthogonal frequency division multiple access system, each carrier group preset by using a preamble of a signal received from a terminal configuring a preamble subchannel in consideration of a cluster, and feeding back the number of carrier groups considered when generating a preamble subchannel having the highest performance among the preamble subchannels configured therein; The method includes configuring a subchannel in consideration of the number of carrier groups fed back from the most terminals.

According to a fifth aspect of the present invention for achieving the above objects, a subchannel allocation method in a terminal of an orthogonal frequency division multiple access system includes extracting preamble subcarriers from received data, and extracting the preamble subcarriers from the received data. Carrier-to-Interference plus Noise Ratio (CINR) measurement process, and the number of carrier groups that pre-set the preamble subchannel considering the carrier in cluster using the preamble subcarriers Each process, measuring CINR dispersion of each preamble subchannel configured using CINR values of the preamble subcarriers, and the number of carrier groups considered when configuring a preamble subchannel having the smallest CINR dispersion. It is characterized in that it comprises a process of feedback to the base station (Feedback) to check.

According to a sixth aspect of the present invention for achieving the above objects, a subchannel allocation method in a base station of an orthogonal frequency division multiple access system includes the steps of: receiving a respective number of carrier groups fed back by respective terminals; And a process of identifying a carrier in cluster fed back from the largest number of terminals and configuring a sub-channel in consideration of the number of carrier groups fed back from the largest number of terminals.

As described above, according to the present invention, when configuring a subchannel in consideration of a carrier in cluster (Requested by the largest number of terminals in an Orthogonal Frequency Division Multiple Access (OFDMA) system), The present invention relates to a subchannel allocation apparatus and method for configuring subchannels by selecting adjacent subcarriers, and adaptively changing the number of carrier groups according to the channel environment to configure subchannels to allocate subchannels more adaptive to channel conditions. This will increase the performance of the system.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. Further, if it is determined that the gist of the present invention may be unnecessarily blurred, detailed description thereof will be omitted.

According to the present invention, when a subchannel is configured in consideration of a carrier in cluster requested by the largest number of terminals in an Orthogonal Frequency Division Multiple Access (OFDMA) system, adjacent subcarriers as many as the number of carrier groups are used. The present invention relates to a subchannel allocation apparatus and method for configuring a subchannel by selecting a subchannel.

In the orthogonal frequency division multiple access system of the present invention, each terminal configures subchannels according to a predetermined carrier in cluster by using a preamble in a signal received from a base station, and among them, the channel state is best. The carrier group number of the subchannels is identified and fed back to the base station. Then, when the base station of the present invention receives each number of carrier groups from the terminals, the base station selects adjacent subcarriers by the number of carrier groups using the number of carrier groups requested by the largest number of terminals and configures subchannels. Allocate

Hereinafter, a process of configuring a subchannel when the number of carrier groups is 2 will be described with reference to FIG. 2. 2 is a diagram illustrating an example of configuring a subchannel in an orthogonal frequency division multiple access system according to an embodiment of the present invention.

Referring to FIG. 2, among the subcarriers constituting one OFDM symbol, the remaining data subcarriers except the guard band and the DC carrier are sequentially numbered. The data subcarriers are divided into groups of a predetermined size in consideration of the number of carrier groups. In this case, the criteria for dividing the group are divided so that one subchannel can be configured by selecting as many carriers as the number of carrier groups in each group. After all, the number of groups of the present invention is the number of carriers constituting the subchannel divided by the number of carrier groups. In the case of FIG. 2, since the number of carrier groups is 2, it is divided into 24 groups and two adjacent carriers are selected from each group to configure one subchannel.

Next, a configuration of a base station and a terminal in an orthogonal frequency division multiple access system according to the present invention will be described with reference to FIGS. 3 and 4.

3 is a diagram illustrating a configuration of a terminal for requesting subchannel allocation adaptive to channel change in an orthogonal frequency division multiple access system according to an embodiment of the present invention.

Referring to FIG. 3, the terminal includes an RF processor 302, an analog / digital converter 304, an OFDM demodulator 306, a subcarrier demapper 308, a channel estimator 310, and an equalizer 312. And a demodulator 314, a decoder 316, a CINR measuring unit 318, and a carrier population number measuring unit 320.

The RF processor 302 includes components such as a front end unit and a filter, and converts a signal of a high frequency band passing through a radio channel into a baseband signal and outputs the signal. The analog-to-digital converter 304 converts the analog baseband signal from the RF processor 302 into a digital signal and outputs the digital signal.

The OFDM demodulator 306 removes a cyclic prefix (CP) from the data from the analog-to-digital converter 304, performs an FFT (Fast Fourier Transform) operation, and outputs data in a frequency domain.

The subcarrier demapper 308 extracts the actual data symbols from the data from the OFDM demodulator 306 and provides them to the equalizer 312, and a symbol (eg, a pilot symbol) at a predetermined position for channel estimation. These extracts are provided to the channel estimator 310, and a preamble is extracted and provided to the CINR measurer 318.

The channel estimator 310 performs channel estimation using the pilot symbols from the subcarrier demapper 308 and provides the channel estimates to the equalizer 312.

The equalizer 312 performs channel compensation on the data symbols output from the subcarrier demapper 308 using channel estimation values from the channel estimator 310. That is, it compensates for various noise generated in the wireless channel and outputs it.

The demodulator 314 demodulates the symbols from the equalizer 312 according to a modulation scheme of a transmitter and outputs encoded data. The decoder 316 decodes the coded data from the demodulator 314 according to the coding method of the transmitter to restore the original information data.

The carrier-to-interference plus noise ratio (CINR) measuring instrument 318 measures the signal-to-interference noise ratio (CINR) of the preamble subcarriers received from the subcarrier demapping unit 308 to measure the carrier population count (320). To provide.

The carrier group number measuring unit 320 configures a preamble subchannel for each carrier group number considering a carrier in cluster using preamble subcarriers, respectively, and is provided from the CINR meter 318. The CINR variance of each preamble subchannel is measured using the CINR value of the preamble subcarriers. In this case, a detailed description of configuring the preamble subchannel in consideration of the number of carrier groups will be described later in detail with reference to FIG. 7.

In addition, when the carrier group number measuring unit 320 measures the CINR variance of each preamble subchannel, the carrier group number measuring unit 320 checks the number of carrier groups considered in configuring a preamble subchannel having the smallest CINR variance among the preamble subchannels. Feedback.

For example, the carrier group number measuring unit 320 may be set to 2, 4, and 6 carrier groups, and if the number of carrier groups is 2, 4, or 6, each carrier group number is considered. When the preamble subchannel is configured and the preamble subchannel having the smallest CINR distribution is 4, the carrier group feedback is fed back to the base station.

4 is a diagram illustrating a configuration of a base station for allocating a subchannel adaptive to channel change in an orthogonal frequency division multiple access system according to an embodiment of the present invention.

Referring to FIG. 4, the base station according to the present invention includes an encoder 402, a modulator 404, a carrier group number estimator 406, a subchannel configurator 408, a data mapper 410, and a frame buffer 412. , An OFDM modulator 414, a digital-to-analog converter 416, and an RF processor 418.

The encoder 402 encodes an input information bit string at a corresponding code rate and outputs coded bits or symbols. Here, when the number of input information bits is k and the code rate is R, the number of output symbols is k / R. For example, the encoder 402 may be composed of a convolutional encoder, a turbo encoder, a low density parity check (LDPC) encoder, and the like.

The modulator 404 maps the symbols from the encoder 402 to signal points by a corresponding modulation scheme (modulation level) and outputs complex symbols. For example, in the modulation scheme, BPSK (Binary Phase Shift Keying) for mapping one bit (s = 1) to one signal point (complex symbol) and two bits (s = 2) Quadrature phase shift keying (QPSK), 8-ary phase shift keying (8PSK) mapping 3 bits (s = 3) to one complex symbol, and 4 bits (s = 4) 16QAM mapping, and 64QAM mapping 6 bits (s = 6) to one complex symbol.

The carrier group estimator 406 receives the number of carrier groups fed back by each terminal, identifies the number of carrier groups fed back from the largest number of terminals, and provides the number of carrier groups fed back to the sub-channel configurator 408.

The subchannel constructor 408 configures subchannels by selecting adjacent subcarriers by the number of carrier groups using the number of carrier groups selected by the carrier group number estimator 406 to configure the subchannels. To provide. In the subchannel configuration considering the number of carrier groups, the subcarriers constituting one OFDM symbol are divided into groups considering the number of carrier groups, and adjacent subcarriers are selected from each group by the number of carrier groups, thereby configuring the subchannels. Detailed description of configuring a subchannel in consideration of the number of carrier groups will be described later in detail with reference to FIG. 7.

The data mapper 410 subcarrier maps the complex symbols output from the modulator 404 to correspond to the subchannels configured in the subchannel configurator 408, and maps each of the subcarrier mapped complex symbols to an actual frame size. It outputs to the corresponding memory address of the frame buffer 412 corresponding to.

The frame buffer 412 is a buffer for arranging the complex symbols provided to the OFDM modulator 110 in the actual order. The frame buffer 412 sequentially outputs the complex symbols buffered in OFDM symbol units based on time synchronization.

The OFDM modulator 414 converts the complex symbols from the frame buffer 412 into sample data in a time domain by performing an Inverse Fast Fourier Transform (IFFT) operation, and copies a predetermined back portion of the sample data in front of the sample data. To output OFDM symbols.

The digital-to-analog converter 416 converts sample data from the OFDM modulator 414 into an analog signal and outputs the analog signal. The RF processor 418 includes components such as a filter and a front end unit. The RF processor 418 RF-processes a signal output from the digital-to-analog converter 416 so that the signal can be actually transmitted, and then transmits an antenna. It transmits to a wireless channel through a Tx antenna. A signal transmitted from the transmitter is received through a receive antenna (Rx Antenna) of the receiver in the form of multipath channels and noise added.

Hereinafter, a method of adaptively configuring and assigning subchannels to channel changes in an orthogonal frequency division multiple access system according to the present invention configured as described above will be described with reference to the accompanying drawings.

5 is a flowchart illustrating a process of calculating and requesting the number of carrier sets to be allocated a subchannel configured in consideration of a channel change in a terminal of an orthogonal frequency division multiple access system according to an embodiment of the present invention.

Referring to FIG. 5, when the base station of the present invention receives data from the base station in step 500, the base station proceeds to step 502, searches for and extracts a preamble from the received data, and proceeds to step 504 to search for a preamble subcarrier. Carrier-to-Interference plus Noise Ratio (CINR) is measured. In step 506, the preamble subchannel considering the carrier in cluster is preset using the preamble subcarriers. Each carrier group is configured. In this case, a detailed description of configuring the preamble subchannel in consideration of the number of carrier groups will be described later in detail with reference to FIG. 7.

In step 508, the UE measures CINR variance of each preamble subchannel using CINR values of each preamble subcarrier, and proceeds to step 510 to consider configuring a preamble subchannel having the smallest CINR variance. The number of carrier groups is checked and fed back to the base station.

6 is a flowchart illustrating a process of configuring and assigning subchannels in consideration of channel changes in a base station of an orthogonal frequency division multiple access system according to an embodiment of the present invention.

Referring to FIG. 6, the base station of the present invention receives the number of carrier groups fed back by each terminal in step 600, and proceeds to step 602 to identify and select the number of carrier groups fed back from the most terminals. In step 604, the subchannels are configured by selecting adjacent subcarriers by the number of carrier groups using the selected number of carrier groups. In this case, a detailed description of configuring a subchannel in consideration of the number of carrier groups will be described later in detail with reference to FIG. 7.

In step 606, the base station maps the modulated complex symbols to the subcarriers corresponding to the subchannels. In step 608, the base station calculates inverse fast fourier transform (IFFT) the mapped complex symbols into sample data in the time domain. After converting and RF processing for actual transmission, it is transmitted to the terminal.

7 is a flowchart illustrating a process of configuring a subchannel adaptive to channel change in an orthogonal frequency division multiple access system according to an embodiment of the present invention.

Referring to FIG. 7, when a base station or a terminal of an orthogonal frequency division multiple access system according to the present invention detects a subchannel configuration request in step 700, the base station or terminal proceeds to step 702 to determine the number of carrier groups requested. Here, the number of carrier groups is the number of adjacent subcarriers when the subcarriers are selected. That is, step 702 is to determine how many adjacent subcarriers are selected.

In step 704, the terminal or base station of the orthogonal frequency division multiple access system proceeds to step 704 and the remaining data subcarriers other than the guard band and the DC carrier among subcarriers constituting one OFDM symbol have a predetermined size in consideration of the carrier population. Divide into Data Tone groups.

Here, the number of groups is divided by the number of carriers constituting the subchannels divided by the number of carrier groups and divided to form one subchannel by selecting adjacent subcarriers as many as the number of carrier groups in each group.

In step 706, the terminal or base station of the orthogonal frequency division multiple access system selects adjacent subcarriers as many as the number of carrier groups in each data tone group. That is, one subcarrier is selected from each group, and the next subcarrier adjacent to the first selected subcarrier from each group is selected by the number of carrier groups. In this case, a method of selecting a subcarrier from each group defined by the FUSC of IEEE 802.16, which is a standard standard, may be used to select the first subcarrier among adjacent subcarriers selected from each group.

Thereafter, the terminal or base station of the orthogonal frequency division multiple access system proceeds to step 708 to configure a subchannel using adjacent subcarriers of each group selected in step 706.

The process of configuring a subchannel using adjacent subcarriers as many as the number of carrier populations of FIG. 7 is used when a preamble subchannel is configured to identify a carrier group having the best performance. It is used to configure subchannels according to the number of carrier groups requested by.

8 is a graph showing the performance of the sub-channel configuration and the conventional sub-channel configuration adaptive to the channel change of the present invention.

8 is a data amount sent by dividing into FUSC, AMC and the present inventors dynamic according to the speed change based on the time when one terminal is located 500m away from the base station and rotates around the base station based on one cell of the base station. The rate at which the data is broken during the day is graphed. As shown in the graph, it can be seen that the performance of AMC is the highest performance among three allocation techniques up to 10 km / h. Since then, however, it is clear that most of the broken data sent by Dynamic shows high performance.

Apparently, there are many ways to modify these implementations while remaining within the scope of the claims. In other words, there can be many other ways in which the invention may be practiced without departing from the scope of the following claims.

1 is a diagram illustrating a method of configuring a subchannel using FUSC in an orthogonal frequency division multiple access system according to the prior art;

2 illustrates an example of configuring a subchannel in an orthogonal frequency division multiple access system according to an embodiment of the present invention;

3 is a diagram illustrating a configuration of a terminal for requesting subchannel allocation adaptive to channel change in an orthogonal frequency division multiple access system according to an embodiment of the present invention;

4 is a diagram illustrating a configuration of a base station for allocating subchannels adaptive to channel change in an orthogonal frequency division multiple access system according to an embodiment of the present invention;

5 is a flowchart illustrating a process of calculating and requesting a number of carrier sets to be allocated a subchannel configured in consideration of a channel change in a terminal of an orthogonal frequency division multiple access system according to an embodiment of the present invention;

6 is a flowchart illustrating a process of configuring and assigning subchannels in consideration of channel changes in a base station of an orthogonal frequency division multiple access system according to an embodiment of the present invention;

7 is a flowchart illustrating a process of configuring a subchannel adaptive to channel change in an orthogonal frequency division multiple access system according to an embodiment of the present invention;

8 is a graph showing the performance of the sub-channel configuration and the conventional sub-channel configuration adaptive to the channel change of the present invention.

Claims (18)

A subchannel allocation apparatus in an orthogonal frequency division multiple access system, Preamble subchannels are configured by considering each carrier in cluster using a preamble of a received signal, and a preamble subchannel having the highest performance among the configured preamble subchannels. A terminal for feeding back the number of carrier groups considered in generating And a base station constituting a subchannel in consideration of the number of carrier groups fed back from the most terminals. The method of claim 1, The preamble subchannel configured by considering the number of carrier groups in the terminal, And configuring the preamble subchannel by selecting adjacent carriers by the number of carrier groups. The method of claim 1, The subchannel configured in consideration of the number of carrier groups in the base station, And selecting the adjacent carriers by the number of carrier groups to configure the subchannels. An apparatus for allocating subchannels in a terminal of an orthogonal frequency division multiple access system, A subcarrier demapping unit for extracting preamble subcarriers from the received data; A CINR measuring instrument for measuring a carrier-to-interference plus noise ratio (CINR) of the extracted preamble subcarriers; Preamble subchannels considering carrier in clusters are configured for each carrier group number by using the preamble subcarriers, and CINRs of respective preamble subchannels are used using CINR values of the preamble subcarriers. And a carrier group number measuring device for measuring the variance and checking the number of carrier groups considered when configuring the preamble subchannel having the smallest CINR distribution and feeding back to the base station. 5. The method of claim 4, The carrier group number measurement device, The configuration of the preamble subchannel considering the number of carrier groups, The preamble subcarriers are divided into groups having a predetermined size in consideration of the number of carrier groups, and the preamble subchannels are configured by selecting adjacent subcarriers as many as the number of carrier groups from the group. . 6. The method of claim 5, The carrier group number measurement device, When the preamble subcarriers are divided into groups having a predetermined size in consideration of the number of carrier groups, the number of carriers constituting the preamble subchannel is divided into groups divided by the number of carrier group numbers. Subchannel Allocation Device. A subchannel allocation apparatus in a base station of an orthogonal frequency division multiple access system, A carrier group number estimator for receiving a number of carrier groups fed back by respective terminals and checking a carrier in cluster fed back from the largest number of terminals; And a subchannel configurator constituting a subchannel in consideration of the number of carrier groups fed back from the most terminals identified by the carrier group number estimator. 8. The method of claim 7, The subchannel configurator, The configuration of the subchannel in consideration of the number of carrier groups, The subcarriers constituting one Orthogonal Frequency Division Multiple (OFDM) symbol are divided into groups having a predetermined size in consideration of the number of carrier groups, and the subchannels are configured by selecting adjacent subcarriers as many as the number of carrier groups in the group. Sub-channel allocation device, characterized in that. 9. The method of claim 8, The subchannel configurator, When the subcarriers constituting the symbol are divided into groups having a predetermined size in consideration of the number of carrier groups, the number of carriers constituting the subchannel is divided into groups divided by the number of carrier groups. Subchannel Allocation Device. A subchannel allocation method in an orthogonal frequency division multiple access system, Preamble subchannels are configured in consideration of each carrier in cluster using a preamble of a signal received from the terminal, and a preamble having the highest performance among the configured preamble subchannels. Feeding back the number of carrier groups considered when generating the subchannels, And configuring the subchannels in consideration of the number of carrier groups fed back from the most terminals at the base station. The method of claim 10, The preamble subchannel configured by considering the number of carrier groups in the terminal, And configuring the preamble subchannel by selecting adjacent carriers by the number of carrier groups. The method of claim 10, The subchannel configured in consideration of the number of carrier groups in the base station, And selecting the adjacent carriers by the number of carrier groups to configure the subchannels. A subchannel allocation method in a terminal of an orthogonal frequency division multiple access system, Extracting preamble subcarriers from the received data; Measuring a carrier-to-interference plus noise ratio (CINR) of the extracted preamble subcarriers; Configuring a preamble subchannel for each carrier group number based on a carrier in cluster using the preamble subcarriers; Measuring CINR variance of each preamble subchannel configured using the CINR value of the preamble subcarriers; And identifying the number of carrier groups considered when configuring a preamble subchannel having the smallest CINR distribution and feeding back to the base station. 14. The method of claim 13, The process of configuring the preamble subchannel, Dividing the preamble subcarriers into groups having a predetermined size in consideration of the number of carrier groups; And configuring the preamble subchannel by selecting as many adjacent subcarriers as the number of carrier groups in the group. 15. The method of claim 14, The process of dividing the preamble subcarriers into the group includes: And dividing the number of carriers constituting the preamble subchannel into groups equal to the number divided by the number of carrier groups. A subchannel allocation method in a base station of an orthogonal frequency division multiple access system, Receiving a number of carrier groups to which each terminal feeds back; Checking a carrier in cluster fed back from the most terminals; And configuring the subchannels in consideration of the number of carrier groups fed back from the most terminals. 17. The method of claim 16, The process of configuring the subchannels, Dividing subcarriers constituting one Orthogonal Frequency Division Multiple (OFDM) symbol into groups having a predetermined size in consideration of the number of carrier groups; And configuring the subchannels by selecting as many adjacent subcarriers as the number of carrier groups in the group. 18. The method of claim 17, Dividing the subcarriers constituting the symbol into the group, And dividing the number of carriers constituting the subchannel into groups equal to the number divided by the number of carrier groups.

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