KR20100091329A - Apparatus and method for reporting channel quality indication in communication system based on fractional frequency reuse - Google Patents

Abstract

PURPOSE: An apparatus and a method for reporting a channel quality indicator in a communication system based on fractional frequency reuse are provided to reduce waste of a CQI channel and power loss of an uplink due to unnecessary CQI transmission. CONSTITUTION: A base station assigns a CQI channel to the terminal so that a terminal reports CQI(Channel Quality Indication) of FRP1(Frequency Reuse Pattern1)(202). The base station calculates a moving average value about an obtained CINR(Carrier to Interference-plus-Noise Ratio) of FRP1(204). When the moving average value of CINR is smaller than a reference value, the base station additionally assigns a CQI channel(206~210). When the moving average value of CINR is not smaller than the reference value, the base station cancels assignment of a CQI channel of FRP3(216).

Description

Apparatus and method for transmitting channel quality indicators in communication systems based on partial frequency reuse {APPARATUS AND METHOD FOR REPORTING CHANNEL QUALITY INDICATION SYSTEM BASED ON FRACTIONAL FREQUENCY REUSE}

The present invention relates to channel quality indicator (CQI) transmission for operating a fractional frequency reuse (FFR) technique, and in particular, a frequency reuse pattern according to the channel state and the number of users of the terminal. CQI transmission apparatus and method for increasing the number of users that can be scheduled by dynamically allocating channel quality indication channels according to FRP), reducing unnecessary CQI transmission, reducing uplink power loss, and increasing channel state sensitivity will be.

In the IEEE 802.16e system, the base station receives channel information from the terminal and determines adaptive modulation and coding (hereinafter, referred to as 'AMC') to determine a modulation scheme and a coding rate according to the channel state. . In order to transmit channel information to the base station, the base station receives a channel quality indication (hereinafter referred to as "CQI") channel predetermined by the base station and transmits the CQI to the base station every transmission period. If the channel status of the UE identified by the CQI is not good, reduce the amount of data to be transmitted to match the reception error probability to a desired level, and if the channel condition is good, increase the amount of data to be transmitted and the reception error probability is at a desired level. It allows you to send a lot of information while matching.

On the other hand, in case of applying the partial frequency reuse (hereinafter referred to as 'FFR') in the IEEE 802.16e system, the UE may be configured according to the frequency reuse pattern (hereinafter referred to as 'FRP') for efficient allocation of resources. You need to know the channel information. In this case, since the base station must allocate a CQI channel for each FRP to each terminal, the base station requires a lot of CQI channels as compared to a system without FFR.

When each UE reports the CQI for each FRP, the number of CQI channels required increases, so the base station increases the CQI reporting period to time-division the CQI channel to increase the insufficient CQI channel. Therefore, the number of schedulable users is reduced, and the channel state sensitivity decreases as the reporting period increases. In addition, even if the UE does not need to report the CQI for each FRP, overhead such as power loss and waste of frequency and time resources due to unnecessary transmission occurs.

In addition, the longer the reporting period, the lower the channel state sensitivity, which may cause a problem that the AMC accuracy is lowered and the system performance (Throughput) is reduced.

An object of the present invention is to provide an apparatus and method for CQI transmission in a communication system based on partial frequency reuse.

Another object of the present invention is to provide an apparatus and method for transmitting CQI for increasing the number of schedulable users during FFR operation, reducing uplink power loss, and improving system performance.

Another object of the present invention is to allocate the CQI channel by adaptively determining the CQI reporting period according to the channel information received from the terminal by the base station and the number of users to be scheduled in the system that needs to allocate the CQI for each FRP To provide an apparatus and method for.

According to a first aspect of the present invention for achieving the above objects, in a method for transmitting a channel quality indicator (CQI) in a communication system based on partial frequency reuse, the frequency reuse coefficient from the terminal is 1 Receiving a CQI for the first channel, calculating a moving average value of the signal-to-noise ratio of the first channel using the CQI, and a moving average value of the signal-to-noise ratio of the first channel And determining the CQI channel allocation for the second channel having the frequency reuse factor K in comparison with the threshold.

According to a second aspect of the present invention for achieving the above object, in a method for transmitting a channel quality indicator (CQI) in a communication system based on partial frequency reuse, for a plurality of scheduled terminals Assigning a first CQI channel having a frequency reuse factor of 1 and determining a CQI reporting period; and for at least one or more terminals among the plurality of scheduled terminals, a second CQI channel having a frequency reuse factor of K additionally. Determining whether the allocation is necessary, and changing the CQI reporting period according to the second CQI channel allocation having the frequency reuse coefficient of K.

According to a third aspect of the present invention for achieving the above objects, in the apparatus for transmitting a channel quality indicator (CQI) in a communication system based on partial frequency reuse, the frequency reuse coefficient is 1 from the terminal. An FRP resource allocation unit for receiving a CQI for a first channel and calculating a moving average value of the signal-to-noise ratio of the first channel using the CQI, and a moving average of the signal-to-noise ratio of the first channel And a scheduler for allocating the CQI channel for the second channel having the frequency reuse factor K in comparison with the value and the threshold.

According to a fourth aspect of the present invention for achieving the above objects, an apparatus for transmitting a channel quality indicator (CQI) in a communication system based on partial frequency reuse, for a plurality of scheduled terminals And allocating a first CQI channel having a frequency reuse factor of 1, determining a CQI reporting period, and further assigning a second CQI channel having a frequency reuse factor of K to at least one or more of the scheduled terminals. And a scheduler for changing a CQI reporting period according to the second CQI channel allocation, wherein the frequency reuse factor is K.

As described above, the present invention adaptively determines the necessity of allocating the CQI channel for each FRP according to the channel state of the terminal, and determines the transmission period according to the number of users to be scheduled and the number of CQI channels required per terminal. By doing so, there is an advantage of reducing waste of CQI channel and power loss in uplink caused by unnecessary CQI transmission, and improving system performance. In addition, since the CQI transmission period is determined according to the number of users to be scheduled and the necessity of reporting CQI for each FRP, the channel state sensitivity can be increased.

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, detailed descriptions of related well-known functions or configurations will be omitted if it is determined that the detailed description of the present invention may unnecessarily obscure the subject matter of the present invention. Terms to be described later are terms defined in consideration of functions in the present invention, and may be changed according to intentions or customs of users or operators. Therefore, the definition should be made based on the contents throughout the specification.

Hereinafter, the present invention relates to an apparatus and method for transmitting a channel quality indicator (hereinafter referred to as "CQI") in a communication system based on partial frequency reuse (hereinafter referred to as "FFR"). Let's explain. In particular, when operating a frequency reuse pattern (hereinafter referred to as "FRP"), the CQI allocation apparatus and method for increasing the number of schedulable users, uplink power loss and reduction, and system performance will be described. .

1 is an example of an FFR technique to which a CQI channel allocation method is applied according to an embodiment of the present invention. The FFR technique is a method for reducing co-channel interference (CCI) between adjacent cells generated by using FRP1 to increase frequency efficiency. In general, the FFR scheme uses a terminal located at a center region and a border region of a cell differently affected by interference from neighbor cells.

Assuming that the FFR is 3 in FIG. 1, each of the cells 100, 110, and 120 applies the frequency FRP1 in the center region and the frequency FRP3 in the boundary region of the cell. That is, since the cell center has less interference from neighboring cells, the cells 100, 110, and 120 use all subchannels (subchannel groups 1, 2, and 3) in an area where CCI is less affected, and other border areas. Since the interference from the adjacent cell is large, only one subchannel group of the subchannel groups 1,2 and 3 is used. For example, by using subchannel 1 in the boundary region of the cell 100, using subchannel 2 in the boundary region of the cell 110, and using subchannel 3 in the boundary region of the cell 100, Interference can be minimized.

In the communication system based on the FFR, it is possible to apply an absolutely advantageous FRP in terms of data rate according to the channel environment of the terminal. In this case, by selecting a more favorable FRP based on the CQI transmitted for each FRP, it is advantageous in terms of data rate. However, since two CQI channels must be allocated per terminal, the number of schedulable users is reduced by half. As the reporting period of CQI increases, the channel's state sensitivity decreases and the accuracy of AMC application decreases, thereby affecting performance. Accordingly, in the present invention, the necessity of reporting the CQI for each FRP by observing the channel state of the UE can be determined to selectively improve the CQI channel.

2 is a flowchart illustrating CQI transmission in a communication system based on FFR according to an embodiment of the present invention.

Referring to FIG. 2, in step 200, when an initial terminal accesses a call, the base station transmits CQI channel allocation information through a downlink frame in step 202, and allocates a CQI channel to the terminal to allocate CQI of FRP1. Report it. At this point, a procedure of allocating a CQI channel will be described with reference to FIG. 3.

Thereafter, the base station calculates a moving average value for a signal to noise ratio (hereinafter referred to as "CINR") of the FRP1 obtained from the terminal in step 204. The signal to noise ratio may be a Signal to Noise Ratio (SNR), a Signal to Interference plus Noise Ratio (SINR), or a Carrier to Noise Ratio (CNR).

Thereafter, the base station additionally adds a CQI channel to report the CQI of FRP 3 in step 206 when the calculated moving average value of the CINR is less than the reference value in step 206 and continues for a reference time in step 208. Assign. At this point, a procedure of additionally allocating a CQI channel will be described with reference to FIG. 3.

If, in step 206, the moving average value of the CINR is not less than the reference value, proceeds to step 212, if it is maintained for a reference time, it is determined that the CINR of the UE is good and the CQI channel for reporting the CQI of FRP3 Do not allocate separately. That is, since the channel state for FRP1 is good, the channel for FRP1 is maintained as it is.

Thereafter, if the CQI channel for reporting the FRP3 is allocated in step 214, the base station proceeds to step 216 to release the allocation of the CQI channel of the FRP3 (316). Reference will be made to FIG. 4.

Thereafter, the base station repeatedly performs a step (204) of calculating a moving average value of the CINR obtained from the terminal.

The procedure of the present invention is then terminated.

As described above, by reporting only the CQI of FRP 1 for the UE having a good CINR environment of frequency reuse 1, the base station enables the UE to operate in the FRP 1 environment, improve the performance of the system, frequency reuse of the terminal 1 If the CINR of the UE is worsened, the CQIs of the FRP1 and the FRP3 are reported at the same time so that the base station can determine whether the environment of the FRP1 and FRP3 is good to operate selectively. In particular, by observing the channel environment of the terminal and assigning the CQI channel for each FRP only when necessary, the CQI channel can be efficiently used, and the number of schedulable users can be increased. In addition, the performance of the system can be improved by reducing the reporting period of CQI so that accurate AMC can be applied.

3 illustrates a flowchart for determining a reporting period when allocating a CQI channel in an FFR-based communication system according to an exemplary embodiment of the present invention.

Referring to FIG. 3, in step 300, the base station determines if an initial call connection is made by the terminal or an existing terminal additionally allocates a CQI channel for reporting CQI of FRP3 (step 200 or 210 in FIG. 2). step),

In step 302, the base station searches for all the CQI channels and selects the CQI channel having the shortest reporting period among the CQI channels. In this case, when there are a plurality of CQI channels having the same reporting period, the CQI channel having the lowest CQI index is selected. According to the implementation, a method of selecting one of a plurality of CQI channels having the same reporting period may be variously selected.

 In step 304, the base station determines whether the reporting period of the corresponding CQI channel is equal to the maximum value of the reporting period. If the reporting period of the corresponding CQI channel is already the maximum value of the reporting period, increase the reporting period any more so that the new terminal reports the CQI of FRP1 or allocates the CQI channel to additionally report the CQI of FRP3 to the terminal. It can't be terminated without additional allocation.

On the other hand, if the reporting period of the corresponding CQI channel is not already the maximum value of the reporting period, the base station proceeds to step 306 when the other terminal is using the selected CQI channel, or no terminal occupies the corresponding CQI channel to be. If the other terminal does not use the corresponding CQI channel in step 306, proceeds to step 312 to set the reporting period of the corresponding CQI channel to the minimum value, so that the new terminal reports the CQI of FRP1 in step 310, or FRP3 to the terminal Report additional CQIs.

On the other hand, if another UE is using the corresponding CQI channel in step 306, the process proceeds to step 308 and sets the CQI reporting period of the corresponding CQI channel to twice the existing reporting period. Thereafter, in step 310, the CQI of FRP1 is reported to a UE that has made an initial call connection to the corresponding CQI channel time-divided, or the CQI of FRP3 is additionally reported to the base station.

The procedure of the present invention is then terminated.

4 is a flowchart illustrating releasing CQI channel allocation in a communication system based on FFR according to an embodiment of the present invention.

Referring to FIG. 4, in step 400, if the base station terminates a call of a terminal using a random CQI channel or needs to release a CQI channel allocated to report a CQI for FRP3 of the terminal, the call ends. If there is a specified user, simply select a CQI channel assigned for the user (not shown). When the CQI channel allocated to report the CQI of the FRP3 of the mobile station needs to be released, the corresponding CQI channel deassignment command is transmitted to the mobile station in step 402.

Thereafter, in step 404, if the reporting period of the corresponding CQI channel is the same as the minimum value of the reporting period, that is, if the corresponding CQI channel is time-divided and is not shared with other users, the allocation is terminated.

On the other hand, if the reporting period of the corresponding CQI channel is different from the minimum value of the reporting period in step 404, since the CQI channel is time-divided and shared with other users in step 406, the reporting period of the corresponding CQI channel is changed to 1/2 times. .

In step 408, the base station transmits allocation information to the terminal to report the CQI for the user sharing the corresponding CQI channel in a changed cycle. Through this process, if the number of users to be scheduled in the cell is reduced or if the allocation of the CQI channel set to report the CQI of FRP3 is released, the reporting period of the previously allocated CQI can be kept as short as possible. It can increase the sensitivity of the state and improve the accuracy of AMC application.

The procedure of the present invention is then terminated.

5 illustrates a base station for CQI transmission in a communication system based on FFR according to an embodiment of the present invention.

As shown. Scheduler 500, MAP Generator 502, Encoder 504, Modulator 506, Resource Mapper 508, OFDM Modulator 510, Digital to Analog Converter (DAC) 512, Radio Frequency (RF) And a transmitter 514 and an FRP resource allocation unit 516.

Referring to FIG. 5, first, the scheduler 500 performs resource scheduling using channel information (CQI information) for each terminal fed back through a feedback channel (for example, a CQI channel), and performs the scheduling result (resource allocation information, Control information, etc.) to the MAP generator 502.

The scheduler 500 allocates a CQI channel having a frequency reuse factor of K by comparing the moving average value of the signal-to-noise ratio of the CQI channel having a frequency reuse factor of 1 with a threshold. That is, the scheduler 500 allocates a CQI channel having a frequency reuse coefficient of K when the moving average value of the signal-to-noise ratio of the CQI channel having a frequency reuse coefficient of 1 is less than a threshold value, and the CQI having the frequency reuse coefficient of 1. When the moving average value of the signal-to-noise ratio of the channel is not smaller than the threshold, the CQI channel for the second channel having the frequency reuse factor K is not allocated additionally.

In addition, the scheduler 500 determines the release of the CQI channel for the second channel having a frequency reuse coefficient of K by comparing the moving average value of the signal-to-noise ratio of the CQI channel having the frequency reuse coefficient of K and a threshold. When the scheduler 500 releases the CQI channel for the second channel having the frequency reuse factor K, when the CQI report period for the CQI channel to be released is greater than the minimum transmission report period, the scheduler 500 of the CQI channel to be released. Change the transmission report period to 1/2.

When the scheduler 500 allocates the CQI channel for the second channel having the frequency reuse factor K, the scheduler 500 selects the CQI channel having the shortest CQI reporting period, and the scheduler reports the CQI for the selected CQI channel. When the period is smaller than the maximum transmission report period, the transmission report period of the selected CQI channel is changed twice.

The FRP resource allocator 516 receives a CQI for the first channel having a frequency reuse factor of 1 from the terminal, calculates a moving average value of the signal-to-noise ratio of the first channel using the CQI, The result is provided to the scheduler 500. In addition, the FRP resource allocator 516 calculates a moving average value of a signal-to-noise ratio of a CQI channel having a frequency reuse coefficient of K when the second channel having the frequency reuse coefficient of K is allocated, and calculates a result of the scheduler. Provided at 500.

The MAP generator 502 generates MAP information (DL MAP / UL MAP) according to the scheduling result received from the scheduler 500. According to the present invention, the MAP generator 502 includes uplink control region allocation information in the MAP information at predetermined intervals under the control of the scheduler 300. In addition, when uplink control region allocation information is changed, the MAP generator 502 includes uplink control region allocation information in the MAP information for a predetermined number of frames under the control of the scheduler 500.

The encoder 504 encodes the information bit stream from the MAP generator 502 to generate code symbols. For example, the encoder 502 uses an encoder using a convolutional code (CC), an encoder using a block turbo code (BTC), and a convolutional turbo code (CTC). And an encoder using a zero tailing convolutional code (ZT-CC). The modulator 506 modulates the code symbols from the encoder 304 in a predetermined modulation scheme to generate modulation symbols. Since the MAP information is information that all terminals should receive, it is assumed that the MAP information is coded and modulated using a robust modulation scheme (eg, QPSK, R = 1/2, Repetition = 6). .

The resource mapper 508 maps the data from the modulator 506 to a predetermined resource (eg, a preceding section of the frame) and outputs the data. The OFDM modulator 510 OFDM modulates the resource mapped data from the resource mapper 508 to generate an OFDM symbol. In this case, the OFDM modulation includes an Inverse Fast Fourier Transform (IFFT) operation, Cyclic Prefix (CP) insertion, and the like.

A digital to analog converter (DAC) 512 converts sample data from the OFDM modulator 510 into an analog signal and outputs the analog signal. The RF transmitter 514 converts the baseband signal from the DAC 512 into a radio frequency (RF) signal and transmits the same through an antenna. The terminals receiving the MAP information thus transmitted receive forward data from the base station according to the MAP information, and transmit reverse data to the base station.

Meanwhile, in the detailed description of the present invention, specific embodiments have been described. However, various modifications may be made 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 determined not only by the scope of the following claims, but also by the equivalents of the claims.

1 is an exemplary diagram of an FFR technique to which a CQI channel allocation method is applied according to an embodiment of the present invention;

2 is a flowchart for CQI transmission in a communication system based on FFR according to an embodiment of the present invention;

3 is a flowchart for determining a reporting period when allocating a CQI channel in an FFR-based communication system according to an embodiment of the present invention;

4 is a flowchart for releasing CQI channel allocation in a communication system based on FFR according to an embodiment of the present invention;

5 is a configuration diagram of a base station for CQI transmission in a communication system based on FFR according to an embodiment of the present invention.

Claims (20)

A method for transmitting a channel quality indicator (CQI) in a communication system based on partial frequency reuse, Receiving a CQI for the first channel having a frequency reuse factor of 1 from the terminal; Calculating a moving average value of the signal-to-noise ratio of the first channel using the CQI; And determining a CQI channel allocation for a second channel having a frequency reuse factor of K by comparing a moving average value of the signal-to-noise ratio of the first channel and a threshold value. The method of claim 1, When the moving average value of the signal-to-noise ratio of the first channel is less than a threshold, the CQI channel is allocated to the second channel having the frequency reuse factor K. And if the moving average value of the signal-to-noise ratio of the first channel is not smaller than a threshold, the CQI channel for the second channel having the frequency reuse factor K is not allocated. The method of claim 1, Calculating a moving average value of the signal-to-noise ratio of the CQI channel for the second channel having the frequency reuse factor K; And determining a CQI channel release for a second channel having a frequency reuse factor of K by comparing a moving average value of the signal-to-noise ratio of the second channel and a threshold value. The method of claim 3, wherein When releasing the CQI channel for the second channel having the frequency reuse factor K, when the CQI reporting period for the CQI channel to be released is greater than the minimum transmission reporting period, the transmission reporting period of the CQI channel to be released is 1 /. The method further comprises the step of changing to two. The method of claim 1, Selecting a CQI channel having the shortest CQI reporting period when allocating a CQI channel for a second channel having the frequency reuse factor K; If the CQI reporting period for the selected CQI channel is less than the maximum transmission reporting period, further comprising doubling the transmission reporting period of the selected CQI channel. A method for transmitting a channel quality indicator (CQI) in a communication system based on partial frequency reuse, Allocating a first CQI channel having a frequency reuse factor of 1 and determining a CQI reporting period for a plurality of scheduled terminals; Determining whether a second CQI channel allocation having a frequency reuse factor of K is additionally necessary for at least one or more of the scheduled terminals; And changing a CQI reporting period according to the second CQI channel allocation, wherein the frequency reuse factor is K. The method of claim 6, In addition, the process of determining whether a second CQI channel allocation having a frequency reuse factor of K is required, Calculating a moving average value of a signal-to-noise ratio of a channel corresponding to the first CQI channel having the frequency reuse factor of 1; And comparing a moving average value of the signal-to-noise ratio of the channel with a threshold. The method of claim 6, The process of changing the CQI reporting period according to the second CQI channel allocation with the frequency reuse coefficient K, Selecting the corresponding CQI channel with the shortest CQI reporting period, And when the CQI reporting period for the selected corresponding CQI channel is smaller than the maximum transmission reporting period, changing the transmission reporting period of the selected CQI channel to double. The method of claim 6, Calculating a moving average value of a signal-to-noise ratio of a channel corresponding to the CQI channel for the second CQI channel having the frequency reuse factor K; And determining a CQI channel release for a second channel having a frequency reuse factor of K by comparing a moving average value of the signal-to-noise ratio of the second channel and a threshold value. The method of claim 9, When releasing the second CQI channel having the frequency reuse factor K, when the CQI reporting period for the CQI channel to be released is greater than the minimum transmission reporting period, the transmission reporting period of the CQI channel to be released is changed to 1/2. The method further comprises the step of. An apparatus for transmitting a channel quality indicator (CQI) in a communication system based on partial frequency reuse, An FRP resource allocation unit for receiving a CQI for a first channel having a frequency reuse coefficient of 1 from a terminal and calculating a moving average value of a signal-to-noise ratio of the first channel using the CQI; And a scheduler for allocating a CQI channel to a second channel having a frequency reuse factor of K, compared to a moving average value and a threshold value of the signal-to-noise ratio of the first channel. The method of claim 11, The scheduler is When the moving average value of the signal-to-noise ratio of the first channel is less than a threshold, the CQI channel is allocated to the second channel having the frequency reuse factor K. And when the moving average value of the signal-to-noise ratio of the first channel is not smaller than a threshold, the CQI channel for the second channel having the frequency reuse factor K is not allocated. The method of claim 11, The FRP resource allocation unit calculates a moving average value of the signal-to-noise ratio of the CQI channel for the second channel having the frequency reuse coefficient of K, And the scheduler determines a CQI channel release for a second channel having a frequency reuse coefficient of K by comparing a moving average value of the signal-to-noise ratio of the second channel and a threshold value. The method of claim 13, The scheduler is When releasing the CQI channel for the second channel having the frequency reuse factor K, when the CQI reporting period for the CQI channel to be released is greater than the minimum transmission reporting period, the transmission reporting period of the CQI channel to be released is 1 /. Device for changing to two. The method of claim 11, The scheduler selects the CQI channel having the shortest CQI reporting period when allocating the CQI channel for the second channel having the frequency reuse coefficient of K, And when the CQI reporting period for the selected CQI channel is smaller than the maximum transmission reporting period, changing the transmission reporting period of the selected CQI channel to double. An apparatus for transmitting a channel quality indicator (CQI) in a communication system based on partial frequency reuse, For a plurality of scheduled terminals, allocate a first CQI channel having a frequency reuse factor of 1, determine a CQI reporting period, For at least one or more of the scheduled terminals, it is further determined whether a second CQI channel allocation with a frequency reuse factor of K is needed. And a scheduler for changing a CQI reporting period according to a second CQI channel assignment having the frequency reuse factor of K. The method of claim 16, When determining whether a second CQI channel allocation having a frequency reuse coefficient of K is necessary, calculating a moving average value of a signal-to-noise ratio of a channel corresponding to the first CQI channel having the frequency reuse coefficient of 1; Further includes an FRP resource allocation, And the scheduler compares the moving average of the signal-to-noise ratio of the channel with a threshold. The method of claim 16, The scheduler selects the corresponding CQI channel having the shortest CQI reporting period when changing the CQI reporting period according to the second CQI channel allocation having the frequency reuse coefficient of K, And when the CQI reporting period for the selected corresponding CQI channel is smaller than the maximum transmission reporting period, changing the transmission reporting period of the selected CQI channel to twice. The method of claim 16, And an FRP resource allocation unit for calculating a moving average value of a signal-to-noise ratio of a channel corresponding to the CQI channel for the second CQI channel having the frequency reuse factor K, And the scheduler determines a CQI channel release for a second channel having a frequency reuse coefficient of K by comparing a moving average value of the signal-to-noise ratio of the second channel and a threshold value. The method of claim 19, The scheduler is When releasing the second CQI channel having the frequency reuse factor K, when the CQI reporting period for the CQI channel to be released is greater than the minimum transmission reporting period, the transmission reporting period of the CQI channel to be released is changed to 1/2. Device characterized in that.

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