M.N. Chesnokov - Dr.Sc. (Eng.), Professor, Head of Department, LTD «Special Technological Center» (St. Petersburg). E-mail: chesnokovmn@yandex.ru A.A. Soloviev - Engineer, LTD «Special Technological Center» (St. Petersburg). E-mail: alanight@mail.ru A.A. Litvinov - Engineer, LTD «Special Technological Center» (St. Petersburg). E-mail: alalli.spb@gmail.com

A turboequalization technique for data transmission over time-varying frequency-selective fading channels based on robust filtering and low-density parity-check (LDPC) coding is proposed. Assuming channel noise to be non-Gaussian, due largely to impulsive phenomena, method of nonlinear signal filtering for worst-case noise distribution is implemented for system synthesis. As result nonlinear limitation function is incorporated into signal processing algoritm to mitigate the effects of channel estimation error and impulsive noise and to prevent severe error propagation in turbo processing. For simulation purposes Simulink model consisted of BPSK transmitter, turboequalizer and channel with AWGN, ISI and Impulse noise was created. Performance comparison with different types of turbo equalizers demonstrates the advantage of the proposed turbo equalizer. The complexity of the obtained turboequalizer scheme usually lower than that of many turboequalizers using maximum a posteriori equalizers performing joint channel estimation and detection. Simulation results show that the proposed robust techniques offer significant performance gain compared to estimators without the limiting function in impulsive noise, with little attendant increase in computational complexity. Also, employing LDPC coding in turboequlization provide high coding gain in comparison to scheme with convolutional coding. Loss from imperfect channel coefficients knowledge also calculated through modeling.

 

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