Designing Rate-Compatible Irregular Repeat Accumulate Codes through Splitting

A new scheme of rate-compatible (RC) irregular repeat accumulate (IRA) codes is proposed which can be encoded and decoded using a single encoder-decoder pair and which can provide good performance across a wide range of code rates. Conventional strategies generally start from a low-rate mother code and puncture the rate up. Considering that the initial transmissions (and hence the higher-rate codes) are most important, we propose to start from a good high-rate code and "split" the rate down. Rather than do it gradually in a greedy manner, we propose to design a good one-shot-split to control the worst-case (lowest-rate) performance, and subsequently work out all the intermediate rates. We show the proposed strategy is both simple and powerful resulting in RC-IRA codes that outperform the existing ones.