LDPC 编码辅助的判决反馈信道估计与均衡方法

Under the environment of severely channel frequency selective fading, the traditional orthogonal frequency division multiplexing (OFDM) non-blind channel estimation and equalization method has poor system bit error rate performance, and needs to increase the insertion of pilot symbols in a signal, which reduces the system throughput. A low density parity check code (LDPC) - aided decision feedback channel estimation and equalization method is proposed for the above problems. The proposed method introduces the LDPC coding gain into the decision feedback loop, which improves the convergence. And it achieves the asymptotic performance of non-blind channel estimation and equalization methods under the condition of few pilot symbols inserted. Meanwhile, an improved channel estimation algorithm based on conditional maximum likelihood (CML) principle is proposed. This algorithm detects the effective tap signals based on the principle of constant false alarm to improve the channel estimation accuracy, and can be combined with the proposed decision feedback channel estimation and equalization method. The simulated results show that, under the channel environment selected in the simulation, the LDPC-aided decision feedback channel estimation and equalization method has 11 - 13 dB improvement in bit error performance compared with the traditional decision feedback method, and has excellent system error performance and robustness.