Design of Rate-Compatible Irregular Repeat-Accumulate Codes

We consider the design of efficient rate-compatible (RC) irregular repeat-accumulate (IRA) codes over a wide code-rate range. The goal is to provide a family of RC codes to achieve high throughput in hybrid automatic repeat request (ARQ) scheme for highspeed data packet wireless systems. As a subclass of low-density parity-check (LDPC) codes, IRA codes have an extremely simple encoder and a low-complexity decoder, while providing capacity-approaching performance. We focus on a hybrid design method which employs both puncturing and extending. We propose a simple puncturing method based on minimizing the maximal recoverable step of the punctured nodes. We also propose a new extending scheme for IRA codes by introducing the degree-1 parity bits for the lower rate codes, and obtaining the optimal proportions of extended nodes through density evolution analysis. The throughput performance of the designed RC-IRA codes in hybrid ARQ is evaluated for both additive white Gaussian noise and block fading channels. Simulation results demonstrate that on designed RC codes offer good error-correction performance over a wide rate range and provide high throughput, especially in the high and low signal-to-noise ratio regions.