Sub-optimal joint equalization and decoding approach for SC-FDE

Abstract

Single Carrier Frequency Domain Equalization (SC-FDE) is suitable for high data rate transmission over severely time dispersive channels due to the frequency domain implementation of the receiver. In this paper we are propose to use jointly a low complexity Turbo equalizer and Turbo decoder in SC-FDE, Turbo equalizer consist of feed forward filter and feedback filters are in frequency domain (FD). And the decoder is Soft input Soft output (SISO) Max-Log-MAP (Maximum a posteriori probability) decoder. For the equalizer and decoder, the sub-optimal values of filter co-efficients and parameters are designed respectively to maximize SINR, finally the performance gain is improved. The filter co-efficients are derived on Matched filter (MF) criteria. In the simulation results we will show that the Soft decisions are powerful than the Hard decisions. All the decoder Algorithms are compared in terms of BER and showing that the performance gain of Max-Log-MAP decoder is superior than all decoders with slight complexity but there is a tradeoff between performance and complexity. For equalizer, as the number of iterations are increases the performance is improved, we will show the performance for the iterations of maximum 8 for the code length of N=1024.