Improved T/2 fractional spaced coordinate transforming blind equalization method

A technology of coordinate transformation and fractional interval, applied in the field of blind equalization algorithm of inter-symbol interference, can solve the problems of large residual error and slow convergence speed, and achieve the effect of small residual error, fast convergence speed and reduced calculation amount

Inactive Publication Date: 2010-02-17
NANJING UNIV OF INFORMATION SCI & TECH
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Problems solved by technology

[0004] The purpose of the present invention is to solve the disadvantages of slow convergence speed and large residual error in the Fractional Interval Blind Equalization Method (T/2-FSE-CMA) when equalizing high-order QAM sig

Method used

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  • Improved T/2 fractional spaced coordinate transforming blind equalization method
  • Improved T/2 fractional spaced coordinate transforming blind equalization method
  • Improved T/2 fractional spaced coordinate transforming blind equalization method

Examples

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Effect test

Embodiment 1

[0064] [Example 1] Use a mixed-phase underwater acoustic channel c=[0.3132-0.1040 0.8908 0.3134]; the transmitted signal is 16QAM, the equalizer weight length is 32, the signal-to-noise ratio is 25dB, and the weight length of each sub-channel equalizer is 16 , the weight vector is initialized as the center tap, and the step size μ of the three methods T / 2-FSE , μ T / 2-FSE-CTCMA , μ T / 2-FSE-RCTCMA They are 0.000006, 0.00003, and 0.0009 respectively. 5000 Monte Carlo simulation results, such as Figure 4 shown.

[0065] Figure 4 (a) simulation result shows, on steady-state error, the method T / 2-FSE-RCTCMA of the present invention has reduced 2dB than T / 2-FSE-CTCMA method, than T / 2-FSE-CMA method, has reduced 5dB; in terms of convergence speed, the T / 2-FSE-RCTCMA method of the present invention has the fastest convergence, which is nearly 2000 steps faster than the T / 2-FSE-CMA method. Figure 4 (b) shows that under different signal-to-noise ratios, the root mean square error...

Embodiment 2

[0066] [Embodiment 2] Time-varying channel c 1 The transfer function of c 1 =[0.9656-0.09 060.0578 0.2368], the transmitter transmits 5000 signal points, and the channel changes to channel c 2 , whose transfer function is c 2 =[-0.35001], transmit 10000 signal points, the channel changes to channel c 3 , whose transfer function is c 3 =[0.3132 -0.1040 0.8908 0.3134]. With the sampling of the transmitted signal at different times, the channel zero-pole distribution changes, so as to simulate the time-varying characteristics of the channel.

[0067] The transmitted signal is 16QAM, the weight length of the equalizer is 32, the signal-to-noise ratio is 25dB, the weight length of each sub-channel equalizer is 16, and the weight vector is initialized as the center tap. In the time-varying channel, the step size parameters of the three methods As shown in Table 1. 500 Monte Carlo simulation results, such as Figure 5 shown.

[0068] Table 1 Simulation parameters of three met...

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Abstract

The invention discloses an improved T/2 fractional spaced coordinate transforming blind equalization method (T/2-FSE-RCTCMA). Aiming at the defects of low convergence speed and large remainder error of a fractional spaced blind equalization method (T/2-FSE-CMA) during equalizing a higher order QAM signal, the improved method adopts the following steps: separately equalizing a real part and an imaginary part of an input signal of a fractional spaced blind equalizer by analyzing the distribution characteristic of a 16QAM signal constellation diagram; transforming output signals onto the same circle by utilizing coordinate transformation so as to obtain a constant modulus error function after the coordinate transformation; and using the error function to adjust weight vectors of each path of blind equalizers of the T/2 fractional spaced blind equalizer. The improved method effectively overcomes erroneous judgments of the T/2 FSE CMA method to multi-modulus higher order QAM signals during equalizing. The T/2-FSE-RCTCMA method has high convergence speed and small mean square error.

Description

technical field [0001] The invention relates to an improved blind equalization method for T / 2 fractional interval coordinate transformation, and belongs to the technical field of blind equalization algorithms for overcoming inter-symbol interference (Inter-Symbol Interference, ISI) caused by multipath fading of underwater acoustic channels. Background technique [0002] In underwater acoustic communication, blind equalization technology that does not require training sequences is the main means to eliminate inter-symbol interference (Inter-Symbol Interference, ISI) (see literature: [1] Dabeer O, Masry E. Convergence analysis of the constant modulus algorithm [J ]. IEEE Transactions on Information Theory, 2003, 49(6): 1447-1464). Among them, the Porter interval blind equalizer (see literature: [2] Qiu Tianshuang et al. Adaptive signal processing in communication. Electronic Industry Press. 2005) has a simple structure, but slow convergence speed and large steady-state error; ...

Claims

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Application Information

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IPC IPC(8): H04B13/02H04L1/00
Inventor 郭业才赵雪清
Owner NANJING UNIV OF INFORMATION SCI & TECH
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