H-ARQ Rate-Compatible Structured LDPC Codes

Abstract

In this paper, we design families of rate-compatible structured LDPC codes suitable for hybrid ARQ applications with high throughput. We devise a systematic technique of low complexity for the design of structured low-rate LDPC codes from higher rate ones. These codes have a good performance on the AWGN channel and are robust against erasures and puncturing. The codes designed here are protograph-based codes and have fast encoding and decoding structures. These low rate codes are used as the parent codes of rate-compatible families. Then, we propose a number of algorithms for puncturing the codes in a rate compatible manner to construct codes of higher rates. The two most promising ones are the random puncturing search technique and progressive node puncturing. We show that using the techniques in this paper one could construct a high throughput rate compatible family with codes whose rates are in the range from 0.1 to 0.9 and which are within 1 dB from the channel capacity and have good error floors