Design and analysis of simple irregular LDPC codes with finite-lengths and their application in CDMA systems
In this paper, we design and optimize simple irregular low-density parity-check (LDPC) codes for finite-length applications where the asymptotic noise threshold of the channel cannot play as a dominant optimization factor. Our design procedure is based on some observations resulted from analytical study of these codes. Although we present our design procedure for some specified rates but it can generally be used for any rate. Specifically, we design a simple irregular LDPC code for IS-95 and compare its performance with the other reported codes [1-3] for this application. Our results show a 3.7-fold increase in the capacity at bit error rate (BER) equal to 10(-5) compared to the low-rate orthogonal convolutional codes and 1.2 times increase compared to a high performance LDPC code of Reference [3]. Copyright (c) 2004 John Wiley & Sons, Ltd.
irregular ldpc codes cdma capacity code optimization finite length codes girth control