In wireless communication systems, the error performance in the high signal-to-noise-ratio (SNR) region determines the reliability and quality of data transmission. Among existing error-control techniques, channel coding is of particular interest to enhance the overall performance of such system. In this paper, we investigate the error performance of the protograph low-density parity-check (LDPC) codes over Rayleigh fading channels. To obtain robust error-correction capability, we construct two improved ARA (i.e., IARA1 and IARA2) codes based on the extrinsic information transfer (EXIT) algorithm and the asymptotic weight distribution (AWD) function. We further analyze the asymptotic performance of the IARA1 code and the IARA2 code from the perspective of decoding threshold, typical minimum distance ratio (TMDR), and bit-error rate. Both the analytical and simulated results show that the IARA1 code and IARA2 code outperform the well-performing accumulate-repeat-by-4-jagged-accumulate (AR4JA) code in the high SNR region. As a consequence, the IARA1 code and IARA2 code appear to be better candidates for use in wireless communication applications with fast fading.