Orthogonal Wavelet Transform Blind Equalization Algorithm For MIMO Systems

In the past years, the demand of wireless communication data traffic has been increased, it accelerate the evolution and application of the broadband wireless commu-nication technical, so the signal processing techniques is important in multiple-input multiple-output (MIMO) systems.In order to remove inter-symbol interference, the blind equalization technique is always used, this text firstly studies the blind equalization techniques in simple-input multiple-output (SIMO) systems, and the orthogonal wavelet transform blind equalization algorithm for MIMO systems based on SVD, the wavelet theory is used to reduce the autocorrelation of the input signals and increase the performance of the algorithm. Finally, a semi-blind algorithm for MIMO systems based on super-exponential iterative is proposed. The main contributions are as follows:1Blind Equalization Algorithm Based on the Orthogonal Wavelet Transform for SIMO SystemsIn order to improve the anti-fading and constant modulus blind equalization algorithm performance of SIMO system. A blind equalization algorithm based on the orthogonal wavelet transform for Simple-Input Multiple-Output system is proposed, the signals can be equalized in wavelet transform domain. The wavelet transform is used to reduce the autocorrelation of the input signals. After the analysis and computer simulation, it can be seen that this algorithm has better performance than CMA in SIMO system.2Orthogonal wavelet multi-modulus blind equalization algorithm for MIMO system based on SVD(1)The channel cannot be effective equalization if the output signals load into equalizer directly. The received signals are transformed into an orthogonal signal subspace via singular value decomposition (SVD), then the real part and the imaginary part are processed respectively using multi-modulus algorithm (MMA). A multi-modulus blind equalization algorithm for MIMO systems based on SVD is proposed, the performance of the equalizer has been improved. (2)In order to accelerate the convergence rate of MMA, an orthogonal wavelet multi-modulus blind equalization algorithm for MIMO systems based on SVD is proposed, the normalized orthogonal wavelet is used to reduce the autocorrelation of the received signals, so it can get a better result and clearer constellation diagram.3Semi-Blind Equalization Algorithm for MIMO Systems Based on Super-Exponential IterativeIn order to improve the equalized effect of MIMO systems and overcome the shortcoming of not clearly eye pattern in the semi-blind algorithm of CMA combined with soft decision-directed (SDD), and satisfy the transmission requirement of high-order quadrature amplitude modulation (QAM) signals, a semi-blind equalization algorithm for MIMO systems based on super-exponential iterative (SEI) is proposed. The SEI is used to whiten the received signals and optimize the step size of CMA to obtain faster convergence rate and lower mean square error. It shows that this method has its feasibility and availability, it has faster convergence rate and lower steady state error, it also have clearer eye pattern than before.