Interference Cancellation Using Iterative Equalization for Communication Networks

Inter symbol interference (ISI) constitutes a major impediment to reliable communications in multipath channels. We proposed a low complexity soft feedback Interference canceller (SFEIC) that combines the equalizer outputs and a priori information to form more reliable estimates and perform successive interference cancellation. The receiver performs soft output decisions, achieved by a soft-input soft-output (SISO) detector and a SISO channel decoders, through an iterative process. Simulation results are presented showing that the proposed SFEIC BER perform well compared with MAP equalizer and outperform the conventional MMSE decision feedback equalizer. The results are presented for rate ½ turbo codes with Quadrature-phase shift keying (QPSK) modulation, transmitted over inter symbol interference (ISI) channel having severe frequency distortion. The performance is about 0.8dB gain over MMSE DFE equalizer at bit-error rate of 10^-5.