Orthogonal wavelet multi-mode blind equalization method based on chaos optimization

Abstract

The invention discloses a chaos-optimized orthogonal wavelet multi-mode blind equalization method (CO-WT-MMA). It includes the following steps: pass the transmitted signal a(k) through the impulse response channel h(k) to obtain the channel output vector x(k); use the channel noise n(k) and the channel output vector x(k) to obtain the orthogonal wavelet transformer ( WT) input signal y(k)=n(k)+x(k); After the real part and imaginary part of y(k) are subjected to orthogonal wavelet transform and chaos initialization respectively, and then through the corresponding real part and imaginary part The partial equalizer is output to the complex adder to get the output z(k). On the basis of the multi-mode blind equalization method (MMA), the multi-mode blind equalization method (WT-MMA) based on the orthogonal wavelet transform obtained after the normalized orthogonal wavelet transform accelerates the convergence speed, and at the same time utilizes The ergodicity of the chaotic variable disturbs the current point of the weight vector, and the time-varying parameters are used to gradually reduce the disturbance amplitude during the search process, so that the weight vector reaches the global optimal value. The underwater acoustic channel simulation results show that, compared with MMA and WT-MMA, the CO-WT-MMA of the present invention has faster convergence speed and smaller steady-state mean square error.

Description

technical field [0001] The invention relates to an orthogonal wavelet multimode blind equalization method based on chaos optimization. Background technique [0002] In underwater communication systems, the limited bandwidth and multipath effect of the channel have a serious impact on inter-symbol interference (ISI), resulting in poor quality of information transmission. In order to eliminate ISI, blind equalization technology can be introduced at the receiving end, which does not need to transmit periodic training sequences, saves bandwidth, and effectively improves frequency band utilization, communication speed and quality. In the blind equalization method, the constant modulus algorithm (CMA) is suitable for the equalization of the normal mode signal, but the modulus value of the high-order QAM signal is distributed on multiple circles with different radii, and is not constant. , CMA still equalizes high-order QAM signals with the same modulus value, which leads to a lar...

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Problems solved by technology

Using wavelet transform to normalize the energy of the input signal can effectively reduce the correlation between signal and noise (see literature [5] V.P.Kumar S, KVK Kishore and K.H.Kumar.Face Recognition Using Wavelet Based Kernel Locally Discriminating Projection[J]. International Journal of Computer Theory and Engineering. 2010.8, 2(4): 636-641; literature [6] Cooklev T. An Efficient Architecture for Orthogonal Wavelet Transforms [J]. IEEE Signal Processing Letters (S1070-9980), 2006, 13 (2) :77-79), but the wavelet blind equalization still seeks the optimal weight vector according to the gradient direction, which is very sensitive to the initialization of the weight vector, and it is easy to converge to the local minimum

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