Performance of HARQ-Assisted OFDM Systems Contaminated by Impulsive Noise: Finite-Length LDPC Code Analysis

Impulsive noise (IN) constitutes a limiting factor in power-line communication systems, especially in those relying on orthogonal frequency division multiplexing (OFDM). If a single time-domain sample is contaminated by an impulse, all subcarriers become contaminated after the spreading of the discrete Fourier transform-based demodulation. In order to alleviate this problem, hybrid automatic repeat-and-request (HARQ) is often invoked. Moreover, the powerful low-density parity-check (LDPC) codes have been increasingly employed in a variety of current and next-generation communication standards. Against this background, in this paper, we explicitly characterize the performance of LDPC-coded HARQ-assisted OFDM systems in the face of IN, where the performance metrics of the outage probability (OP) and the average number of retransmissions, as well as the effective throughput, are analyzed. First of all, we conceive a new algorithm for evaluating the OP in a realistic finite-length LDPC regime, by adapting both the so-called density evolution technique and the waterfall signal-to-noise ratio analysis method. Following this, both the average number of retransmission attempts and the effective throughput are investigated based on our analysis of the OP. The accuracy of the proposed analysis is confirmed by the simulation results, which also effectively quantify the impact of IN on HARQ-assisted OFDM systems in a finite-length LDPC regime.