An Encoding and Decoding Scheme of LDPC Codes Based on Pulse Position Modulation
一种基于PPM的LDPC编译码方案

In this paper, a low-rate LDPC-PPM scheme is bring forward which can be applied into UWB communication systems. This scheme can provide good performance with low decoding complexity. By changing the mapping style from coded bits to modulated symbols, not only the iterative operations between decoding and demodulation can be avoided, but also Fast Hadamard Transformation (FHT) and the so called A Posteriori Probability FHT (APP-FHT) algorithm can be adopted to further decrease decoding complexity. It can be proved that this scheme is equivalent to low-rate LDPC-Hadamard codes with BPSK modulation. Simulation results show that this scheme can achieve -1.18dB at bit error rate with data length 65536, which is only worse 0.02dB than Turbo-Hadamard codes with BPSK modulation.