High Performance Simplified LDPC Decoder without Knowledge of Multi-path Rayleigh Channel

This paper presents a high performance simplified LDPC decoder which doesn´t need knowledge of multi-path channels and is robust over level mismatches between demodulator and decoder. This decoder also has the benefit of avoiding a high error floor caused by the approximation in the max-log domain known as the min-sum algorithm in categorized Tanner graphs. To overcome error floor and to get the robustness, we apply some individual coefficients to LLR values in every category. Simulation results in AWGN and multi-path fading channels show that even though categorized low profile and approximations are used, good performance is achieved, which can not be achieved by ordinary single coefficient methods (e.g., normalized BP algorithm). Unlike the recently developed simplified algorithms which use the noise variance of the channel estimate, simulation results show that the proposed multi-coefficient method which doesn´t use the noise variance is robust over varying fading conditions