KR20140077456A

KR20140077456A - Channel estimation method

Info

Publication number: KR20140077456A
Application number: KR1020120146289A
Authority: KR
Inventors: 김지훈; 이석규
Original assignee: 한국전자통신연구원
Priority date: 2012-12-14
Filing date: 2012-12-14
Publication date: 2014-06-24

Abstract

Disclosed is a method of estimating a channel. The method of estimating the channel includes the steps of outputting an information symbol including cyclic redundancy check (CRC) codes using a first channel estimation value based on a training symbol; performing CRC verification by channel-decoding and demodulating the information symbol; regenerating an information symbol through modulation and channel encoding if the CRC verification is normal; determining a second channel estimation value by utilizing the regenerated information symbol as a training symbol; and determining a third channel estimation value by calculating a weight-average of the first and second channel estimation values.

Description

{CHANNEL ESTIMATION METHOD}

And more particularly, to a method for improving the accuracy of channel estimation through CRC verification.

Conventional decision directed techniques can ensure frame reception performance. In other words, the decision-directed technique can improve the data transmission efficiency by reducing the information area such as the preamble or the pilot by ensuring the frame reception performance. In addition, the decision-directed technique can improve the resource efficiency and detection performance by estimating the transmitted data signal and using the estimated value of the estimated data signal as a pilot.

However, the error of the estimate is inversely proportional to the signal-to-noise ratio. And, the accuracy of the decision-directed technique is reduced by using the estimated value in which the error occurs as a pilot. In other words, the decision-directed technique reduces gain in low signal-to-noise ratio environments.

The present invention performs channel decoding and demodulation of an information symbol including a CRC (Cyclic Redundancy Check) code to perform CRC verification, reconstructs information symbols when there is no abnormality, and uses the information symbols as training symbols, And provides a channel estimation method capable of improving the channel estimation.

The present invention performs channel decoding and demodulation of an information symbol including a CRC (Cyclic Redundancy Check) code to perform CRC verification, and reconstructs information symbols when there is no abnormality and uses the symbols as training symbols, And operates independently, thereby providing a channel estimation method capable of further combining and improving performance.

The present invention provides a channel estimation method capable of improving the throughput of a channel estimation apparatus by lowering the weight of training symbols in the preamble configuration.

According to an embodiment of the present invention, there is provided a channel estimation method including: outputting an information symbol including a CRC (Cyclic Redundancy Check) code using a first channel estimation value based on a training symbol; Performing channel decoding and demodulation of the information symbols to perform CRC verification; If the CRC verification is not abnormal, regenerating the information symbol through modulation and channel encoding; Using the regenerated information symbol as a training symbol to determine a second channel estimate; And outputting a third channel estimate value by weightedly averaging the first channel estimate value and the second channel estimate value.

The channel estimation method according to an embodiment of the present invention performs channel decoding and demodulation of an information symbol including a CRC (Cyclic Redundancy Check) code, reconstructs an information symbol that has undergone CRC verification and uses the symbol as a training symbol, Can be effectively used for improvement.

The channel estimation method according to an embodiment of the present invention performs channel decoding and demodulation of an information symbol including a CRC (Cyclic Redundancy Check) code, reconstructs an information symbol that has undergone CRC verification and uses the symbol as a training symbol, And independently operated, so that it is possible to further improve the performance by combining them.

The channel estimation method according to an embodiment of the present invention can improve the throughput of the channel estimation apparatus by reducing the weight of training symbols in the preamble configuration.

1 is a block diagram illustrating a channel estimation apparatus according to an embodiment of the present invention.
2 is a diagram illustrating a preamble structure according to an embodiment.
3 is a diagram illustrating a channel estimation method according to an embodiment.

The present invention is characterized in that a cyclic redundancy check (CRC) verified information symbol is reconstructed and used as a training symbol.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

1 is a block diagram illustrating a channel estimation apparatus according to an embodiment of the present invention.

Referring to FIG. 1, the transmission apparatus 101 may calculate a CRC (Cyclic Redundancy Check) value using data. Then, the transmission apparatus 101 can transmit the calculated CRC value to the reception apparatus 102 by including it in the data.

The receiving apparatus 102 may include a channel estimation apparatus 103. [ The receiving apparatus 102 can recalculate the CRC value for the received data using the received data. At this time, the channel estimation apparatus 103 can determine an error occurring in the transmission process by comparing the CRC value received from the transmission apparatus 101 with the CRC value calculated by the reception apparatus 102. Here, the CRC is applied to a portion where a frame is contained in the preamble in order to recover data such as a coding rate or a data length in the receiving apparatus 102.

The channel estimation unit 103 may use the training symbol to obtain the first channel estimation value. Where the training symbols may be symbols used for channel estimation. Also, the training symbols may be signals that the transmitting device 101 and the receiving device 102 know the same. The channel estimation apparatus 103 can detect the information symbol using the first channel estimation value. The information symbol may be a SIG (Signal Field) including frame configuration information and a CRC value calculated based on the frame configuration information. In addition, the channel estimation apparatus 103 can perform CRC verification by demodulating and decoding information symbols.

If there is no abnormality in the CRC verification, the channel estimation apparatus 103 can regenerate the information symbol through modulation and encoding of the information symbol having no anomaly. Then, the channel estimator 103 can use the regenerated information symbol as a training symbol to determine a second channel estimation value. The channel estimator 103 may generate a third channel estimate by weighted averaging the first channel estimate and the second channel estimate. At this time, the third channel estimation value may be a reduced noise variance.

2 is a diagram illustrating a preamble structure according to an embodiment.

Referring to FIG. 2, the HTMF may be a hybrid high-throughput wireless local area network (HT-MF WLAN) using a single antenna. The VHT may be a Very High Throughput WLAN (VHT WLAN). The configuration shown in FIG. 2 may be a preamble configuration of the hybrid type high-throughput wireless LAN and the ultra high-throughput wireless LAN.

Here, LTF (Long Training Field) can be used for fine carrier frequency error compensation and fine time synchronization. Also, LTF (Long Training Field) may be a training symbol used for channel estimation. The SIG (Signal Field) may be an information symbol including frame configuration information and a CRC value calculated based on the frame configuration information.

The high throughput wireless LAN and the ultra high throughput wireless LAN can precede the first channel estimation using L-LTF (Legacy LTF). The high throughput wireless LAN and the ultra high throughput wireless LAN can detect the SIG using the first channel estimation value. The high-throughput wireless LAN and the ultra-high-throughput wireless LAN can predict the detection of data by updating the first channel estimation value using HT-LTF or VHT-LTF.

3 is a diagram illustrating a channel estimation method according to an embodiment.

In step 301, the channel estimation device may decode and demodulate the information symbols using the first channel estimate. In more detail, the channel estimator may extract a first channel estimate using training symbols. Where the training symbols may be symbols used for channel estimation.

The channel estimation apparatus includes:

The first channel estimation value can be extracted based on Equation (1) described above. Here, T1 may be a training symbol transmitted from the transmitting apparatus. Yt may be the training symbol received at the receiving device. H can be a channel, and Nt can be a noise. In other words, the receiving device may receive a signal including a channel passing through, a training symbol transmitted, and noise occurring in the process of being received. The channel estimation apparatus can estimate the first channel estimation value using T1.

Equation (2) represents an information signal received by the receiving apparatus. Here, Yc may be a signal received at the receiving apparatus. And Xc may be an information symbol including frame configuration information and a CRC value calculated based on the frame configuration information. Also, H may be a channel, and Nc may be a noise. In other words, the receiving apparatus can receive a signal including a channel that has passed through, a transmitted information symbol, and noise generated in the process of being received.

The channel estimation apparatus can detect the information symbol using the first channel estimation value.

The second channel estimation value can be extracted based on equations (1), (2), and (3) described above. Here, may be the first channel estimate value estimated by the training symbol. Then, the channel estimation apparatus can detect the corresponding information symbol. Herein, the information symbol may be affected by channel estimation error and noise. The information symbols can be guaranteed to be reliable by channel coding.

The channel estimation apparatus can demodulate and channel-decode the detected information symbols. Then, the channel estimation apparatus can CRC verify the demodulated and channel decoded information symbols.

In step 303, the channel estimation apparatus can determine whether or not the information symbol that has undergone CRC verification is abnormal.

In step 304, the channel estimation device may be in a case where the CRC check is not abnormal. In other words, the channel estimation apparatus can perform modulation and channel encoding of the information symbol when there is no abnormality in the CRC verification result. The channel estimation apparatus can regenerate the information symbol through modulation and channel encoding. Here, the information symbol may be a reconstructed form. Since Xc is a symbol known to the transmitting apparatus and the receiving apparatus identically, it can be used as the training symbol T2.

In step 305, the channel estimator may utilize the regenerated information symbol as a training symbol to determine a second channel estimate. Specifically, the channel estimation apparatus can substitute the utilized training symbol into a signal Yc received from the receiving apparatus. Then, the channel estimator can determine the second channel estimation value using Equation (4).

Where H2 may be a second channel estimate.

In operation 306, the channel estimator may weight-average the first channel estimate and the second channel estimate to output a third channel estimate. At this time, the channel estimation apparatus can determine the third channel estimation value using Equation (5).

In this case, may be the third channel estimate. And, the third channel estimation value may be less dispersed in noise than the first channel estimation value and the second channel estimation value. The third channel estimation value may include channel information that is more accurate than the channel estimation value and the second channel estimation value.

For example, if the training symbols, such as HT-LTF or VHT-LTF, are included in the preamble, the channel estimator may determine the final channel estimate by taking the weighted average one more time.

The methods according to embodiments of the present invention may be implemented in the form of program instructions that can be executed through various computer means and recorded in a computer-readable medium. The computer-readable medium may include program instructions, data files, data structures, and the like, alone or in combination. The program instructions recorded on the medium may be those specially designed and constructed for the present invention or may be available to those skilled in the art of computer software.

While the invention has been shown and described with reference to certain preferred embodiments thereof, it will be understood by those of ordinary skill in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims. This is possible.

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

Claims

Outputting an information symbol including a cyclic redundancy check (CRC) code using a first channel estimation value based on a training symbol;
Performing channel decoding and demodulation of the information symbols to perform CRC verification;
If the CRC verification is not abnormal, regenerating the information symbol through modulation and channel encoding;
Using the regenerated information symbol as a training symbol to determine a second channel estimate; And
And outputting a third channel estimate value by weightedly averaging the first channel estimate value and the second channel estimate value
/ RTI >