Performance of Protograph LDPC Codes over Ergodic Nakagami Fading Channels

The protograph low-density parity-check (LDPC) codes have drawn much attention in the past decade due to their simple structures and outstanding error performance. Unfortunately, the conventional protograph codes designed for additive white Gaussian noise (AWGN) channels can not perform well in ergodic Nakagami fading channels. To address this issue, we construct a new rate-1/2 protograph code, called improved accumulate-repeat-accumulate (JARA) code, by exploiting a modified PEXIT algorithm. We compare the decoding threshold and bit error rate (BER) of the IARA code with the existing protograph codes, the regular LDPC code and the irregular code over ergodic Nakagami fading channels. Both analytical and simulated results show that the proposed IARA code can achieve the lowest BER in the high signal-to-noise-ratio region. Hence, the IARA code can be considered as a good candidate for use in wireless communication systems with fast fading.