Performance of low density parity check coded continuous phase frequency shift keying (LDPCC-CPFSK) over fading channels

Abstract

In this paper, in order to improve bit error performance, bandwidth efficiency and reduction of complexity compared to related schemes such as turbo codes, we combine low density parity check (LDPC) codes and continuous phase frequency shift keying (CPFSK) modulation and introduce a new scheme, called 'low density parity check coded-continuous phase frequency shift keying (LDPCC-CPFSK)'. Since LDPC codes have very large Euclidean distance and use iterative decoding algorithms, they have high error correcting capacity and have very close performances to Shannon limit. In all communication systems, phase discontinuities of modulated signals result extra bandwidth requirements. Continuous phase modulation (CPM) is a powerful solution for this problem. Beside CPM provides good bandwidth efficiency; it also improves bit error performance with its memory unit. In our proposed scheme, LDPC and CPFSK, which is a special type of CPM, are considered together to improve both error performance and bandwidth efficiencies. We also obtain error performance curves of LDPCC-CPFSK via computer simulations for both regular and irregular LDPC code. Simulation results are drawn for 4-ary CPFSK, 8-ary CPFSK and 16-ary CPFSK over AWGN, Rician and Rayleigh fading channels for maximum 100 iterations, while the frame size is chosen as 504. Copyright (C) 2006 John Wiley & Sons, Ltd.