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Channel equalization method and communication system thereof based on precoding

A technology of channel equalization and precoding, which is applied in the field of communication systems based on precoding, and can solve the problems that the effective signal-to-noise ratio of data cannot meet the requirements, the system performance is low, and the system performance is dragged down.

Inactive Publication Date: 2010-06-30
GCI SCI & TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

The reason is that under high-order modulation, the deterioration of system performance due to residual ISI will become very significant, thus seriously curbing the bit error performance
It can be seen from the figure that the slope of the time-frequency equalization scheme based on the QR decomposition of the original channel matrix is ​​not very steep at high SNR, and there are different degrees of error flat. This is because the QR decomposition technology is used in these schemes, so It will cause the signal-to-noise ratio of some sub-data streams at the end of the data block to be significantly lower than the data at the head, that is, the receiving signal-to-noise ratio is uneven, so that the tail data with low signal-to-noise ratio will drag down the system performance at high signal-to-noise ratio
like Figure 4 as shown, Figure 4 It is a schematic diagram of the error flat bottom of the time-frequency equalization scheme based on the QR decomposition of the original channel matrix under high SNR. In this case, no matter how the SNR is improved, the effective SNR of some data cannot meet the requirements; at the same time , it can also be seen from the figure that although the existing technology can completely eliminate ISI, the noise is amplified at the same time, so that the system performance is still low in the area of ​​medium and low signal-to-noise ratio

Method used

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  • Channel equalization method and communication system thereof based on precoding
  • Channel equalization method and communication system thereof based on precoding
  • Channel equalization method and communication system thereof based on precoding

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Embodiment 1

[0082] This embodiment is a single carrier implementation manner of the present invention. The specific process of signal processing is as follows:

[0083] Step S100, perform geometric mean decomposition according to the extended channel matrix H of the original channel matrix H, and obtain an upper triangular matrix R, a unitary matrix P, and a unitary matrix Q. According to mathematics related literature, the geometric mean decomposition of matrix is ​​also called GMD (Geometry Mean Decomposition) decomposition. In this embodiment, the extended channel matrix H of the original channel H is directly subjected to GMD decomposition, and the process is as follows:

[0084] H = QRP H =[Q 1 Q 2 ] T RP H

[0085] Among them, upper triangular matrix R, unitary matrix P and unitary matrix Q can be obtained after decomposition. The values ​​of the elements on the diagonal of the R matrix are all equal:

[0086] r i , ...

Embodiment 2

[0109] This embodiment is a multi-carrier implementation manner of the present invention, that is, it is implemented on an OFDM system. The specific process of signal processing is as follows:

[0110] The original channel matrix H is a Toeplitz circulant matrix. According to the nature of the matrix: any circulant matrix can be decomposed by the Fourier matrix eigenvalue, and then the following channel decomposition form is obtained:

[0111] H = F Nc H Λ H F Nc

[0112] Among them, F is the Fourier matrix of Nc×Nc, Λ H is the eigenvalue matrix of the channel matrix, and Nc is the number of symbols contained in the data block. Therefore, the extended channel matrix has the following decomposition form:

[0113] H ¯ = F Nc H Λ ¯ ...

Embodiment 3

[0160] The present invention also proposes a communication system based on precoding, including a sending end and a receiving end; the sending end includes a modulation module, a T-H precoding module, a cyclic prefix addition module and an antenna, and the receiving end includes an antenna, a cyclic prefix removal module, and a frequency domain Signal processing module, receiving filter module, modulo acquisition module and demodulation module; the aforementioned modules already exist in the existing communication system and will not be described again. The key of the system is that the communication system also includes: a geometric mean decomposition module based on the extended channel, and the sending end also includes a sending filtering module. Such as Figure 8 as shown, Figure 8 It is a schematic diagram of a single-carrier system based on the geometric mean decomposition of the extended channel matrix. The geometric mean decomposition based on the extended channel ...

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Abstract

The invention provides a channel equalization method based on precoding. The method comprises that geometric mean decomposition is carried out on the extended channel matrix H of an original channel matrix H, R matrix, P matrix and Q matrix are obtained and then equalization is carried out, at a sending end, T-H precoding processing is carried out on modulated data according to the R matrix and the data after the T-H precoding is sent and filtered according to the P matrix and at a receiving end, the data after frequency domain signal processing is received and filtered according to the Q matrix. The invention further provides a communication system based on the precoding, which comprises a geometric mean decomposition module based on H, a receiving filtering module and a sending filtering module added to the sending end. The invention can eliminate error floor under high SNR and improve the system performance under low SNR and is compatible with a single or multiple carrier waves communication system. The invention also provides flexible gang scheme so that the system can obtain excellent performance under low complexity.

Description

technical field [0001] The invention belongs to the technical field of wireless broadband access, and specifically proposes a precoding-based channel equalization method and a precoding-based communication system. Background technique [0002] As an effective anti-multipath fading technology for high-speed wireless communication, channel equalization technology is adopted by the 3G long-term evolution system LTE. When the data transmission rate is high, because the maximum multipath delay greatly exceeds the duration of a single transmission symbol, the data received at a certain moment is the superposition of tens or even hundreds of symbols before, so the recovery at the receiving end Raw data flow is incredibly difficult. Mathematically speaking, the channel equalizer first estimates the impulse response matrix of the channel through the channel estimation module, and then performs the inverse operation of the channel matrix on the received signal to restore the data. T...

Claims

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Application Information

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IPC IPC(8): H04L25/03H04L27/26
Inventor 张永强伍沛然
Owner GCI SCI & TECH
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