KR20040054069A - Erasure detection method for Channel Quality Indicator Channel - Google Patents

Abstract

PURPOSE: A method for detecting an erasure of a CQICH(Channel Quality Indicator Channel) is provided to define a threshold value for maintaining receiving quality of a CQICH, and to determine whether to obtain or abandon data, thereby receiving with high performance as reducing data loss. CONSTITUTION: A system receives a signal of a CQICH(S11), and restores a phase of the received signal through a channel estimation value(S12,S13). The system obtains correlation values of restored receiving symbols. The system determines detection values by the correlation values(S15). The system compares one of the two detection values with a threshold value(S16). If the detection values are bigger or equal to the threshold value, the system restores the CQICH signal(S18). If the detection values are smaller than the threshold value, the system erases CQICH data.

Description

Erasure detection method for Channel Quality Indicator Channel

The present invention relates to a method for detecting an erasure of a channel quality indication channel, and more particularly, to determine whether to take or discard data by setting an appropriate threshold value in order to maintain the required reception quality of a channel quality indication channel received from a base station. The present invention relates to a method for detecting erasure of a channel.

In high speed data communication systems (e.g., 1xEV-DV systems), the quality of the channel is of considerable importance.

The channel quality indicator channel (CQICH) is a channel that informs the base station of channel quality measurement information of the best serving sector by the terminal.

Channel quality indication (CQI) information is an important factor that allows the base station to determine adaptive modulation and coding (AMC).

Hereinafter, a channel quality indication channel transmission method according to the prior art will be described with reference to the accompanying drawings.

1 is a block diagram of a transmitter for explaining a channel quality indication channel transmission method in a communication system according to the prior art.

As shown in FIG. 1, CQI value symbols are 4 bit symbols of quantized channel quality measurement information, and CQI DM symbols are 1 bit information in a feedback mode. The CQI cover symbol is composed of a 3-bit symbol indicating an 8-symbol Walsh code indicating best serving sector information.

The CQI value 4-bit symbol is coded in the block encoder 10 by (12, 4) block code, and the coded symbol is re-coded in the sequence iterator 13 by the repetition rule of the CQI. It is fitted.

The repeated symbol is transmitted by covering the 8 symbol Walsh without inserting the DM symbol in the symbol repeater 11 when the transmission mode in the Walsh cover 12 is a full reporting mode. Is a 1-bit feedback mode, the DM symbol in the symbol repeater 11 is inserted and covered with 8 symbol Walsh to be transmitted.

Since CQI information is very important information in 1xEV-DV system, high quality of service (QoS) level should be maintained.

Since the cyclic redundancy checking (CRC) is not transmitted with the CQI in the CQICH, it is not possible to determine whether the received information is properly restored or not.

Therefore, in order to receive CQI information at a desired quality of service level, the receiver uses a method of recovering CQI information by taking only reliable data.

In other words, if a certain threshold is set and the detected value is larger than this threshold, the data is considered to be reliable.

This method is an erasure detection method that sets a specific threshold value and discards the data when the detection value is smaller than the specific threshold value, and determines the data when the detection value is larger than the specific threshold value. .

In this case, if the threshold value is set too large, the CQI reception performance is improved, but the data is discarded (Erasure), so that the CQI information is lost. If the threshold value is set too low, the data loss is small but the CQI reception performance is decreased.

The most important thing in erasure detection is to find a method of determining the detection value that can have high reception performance with little data loss.

The threshold value is determined according to the detection value determination method, and according to which detection value is determined, high CQI reception performance can be achieved with little data loss.

However, in the prior art, there are the following problems.

That is, in the prior art, since there is no CRC information when receiving the CQICH, it is not possible to determine whether the information is properly restored or not.

Therefore, in order to maintain a high quality of service level at the receiver, a certain threshold is given to determine the data when the decision value is larger than the specific threshold, otherwise the data is erased to erase the CQI information. In this case, a method of increasing the power of the received data is used.

However, the determination value determined by the power measurement method is severely affected by noise, so that the measurement error is severe when the received data power is very small. In this case, the probability of losing unnecessary data is increased, thereby degrading performance.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-described problems of the prior art, and the channel quality which determines whether to take or discard data by setting an appropriate threshold value in order to maintain the required reception quality of the channel quality indication channel received from the base station. An object of the present invention is to provide an erasure detection method of an indication channel.

The method for detecting an erasure of the channel quality indication channel according to the present invention comprises the steps of obtaining a correlation value of the symbols received through the channel quality indication channel by the sector information Walsh code and the block code, and determining a detection value from the correlation value. And determining an erasure of the channel quality indication signal according to comparing the detected value with a threshold.

Preferably, the detection value uses the largest correlation value among block-decoded correlation values in the sector selected by the Walsh code and an average value of correlation values of the remaining sectors except the selected sector. Decide

Preferably, the detection value is determined using the largest correlation value and the second largest correlation value among the block-decoded correlation values in the sector selected by the Walsh code.

Other objects, features and advantages of the present invention will become apparent from the detailed description of the embodiments with reference to the accompanying drawings.

1 is a block diagram of a transmitter for explaining a method for transmitting a channel quality indication channel in a communication system.

2 is a flowchart illustrating a method for detecting erasure of a channel quality indication channel according to the present invention.

Hereinafter, a transmission power control apparatus and method according to the present invention will be described with reference to the accompanying drawings.

2 is a flowchart illustrating a method for detecting erasure of a channel quality indication channel according to the present invention.

First, a signal Y of a channel quality indication channel is received (S11), and this is a channel estimation value. Through step S12, the phase of the received signal is restored (S13).

The recovered received symbols are then correlated by decoding the symbol Walsh code and the block code as sector information.

Referring to FIG. 1, the recovered received symbols are obtained by obtaining 128 correlation values generated by decoding 8 symbol Walsh, which is sector information, and block codes 12 and 4, and by using the correlation values. The detection value is determined (S15).

Here, 128 correlation values come out: 8 correlation values determined by 8 symbol Walsh, and (12.4) 16 correlation values generated by block decoding. Therefore, a correlation value of 8 x 16 = 128 is determined.

When the detection value (V) is determined, it is to be detected by the appropriate threshold value. In this case, one of two detection value determination methods based on the correlation value is used.

Here, the first detection value uses the following equation.

here, Is the largest correlation among 16 correlations of (12,4) block decode in the selected sector in the 8 symbol Walsh code,

Is a correlation value of the remaining sectors except the selected sector, that is, an average value of 112 correlation values.

The second detection value [V] is determined by the following equation.

here, Is the second largest correlation of the 16 correlations of the (12,4) block decoder in the Walsh code of the selected sector.

One of the two detection values determined in this manner is compared with the threshold value T (S16).

In this case, the threshold value T is set to an appropriate value based on the two detection values determined, for example, how to set the frame error rate (FER), and minimizes and decreases the data loss lost by the erasure. The decision is made while maintaining the quality of service (QoS) level. In general, the frame error rate is determined.

If the detected value is greater than or equal to the threshold value (S16), the channel quality indication signal is restored (detected) (S18). If the detected value is less than the threshold value, the channel quality indication data is erased. .

Those skilled in the art will appreciate that various changes and modifications can be made without departing from the spirit of the present invention.

Therefore, the technical scope of the present invention should not be limited to the contents described in the embodiments, but should be defined by the claims.

As described above, the present invention has the effect of being able to receive data with high performance while reducing data loss compared to the detection value determination method by power measurement.

Claims (3)

Obtaining a correlation value between the symbols received on the channel quality indication channel by a sector information Walsh code and a block code; Determining a detection value from the correlation value; And determining an erasure of the channel quality indication signal according to the comparison of the detected value with a threshold value. The method of claim 1, wherein the detection value, The channel characterized in that determined by using the average value of the largest correlation value of the block-decoded correlation value in the sector selected by the Walsh code and the correlation values of the remaining sectors except the selected sector (sector) Eraser detection method of quality indication channel. The method of claim 1, wherein the detection value, And erasing the channel quality indication channel using the largest correlation value and the second largest correlation value among the block-decoded correlation values in the sector selected by the Walsh code.