Title :
Enhancing the performance of IDMA system by irregular LDPC codes
Author :
Jingxi Zhang ; Zhisong Bie ; Weiling Wu
Author_Institution :
Key Lab. of Universal Wireless Commun., Beijing Univ. of Posts & Telecommun., Beijing, China
Abstract :
A method to enhance the performance of IDMA system by means of irregular LDPC codes was studied. Interleavers were used as signature character for user identification and iterative turbo detection and decoding approach was employed with reduced complexity. Gaussian approximation was applied to approximate the message probability density function on factor graph with multiple users. Iterative message update formulas on factor graph were derived. Degree profiles were obtained by using the iterative formula. Simulation result shows that the performance of irregular LDPC-Coded LDMA system is better than that of (3,6) regular LDPC-Coded IDMA system in terms of BER and performance gain about 0.6 dB is achieved at BER 10s with 8 users for AWGN multiple access channel.
Keywords :
AWGN channels; approximation theory; error statistics; interleaved codes; iterative decoding; multi-access systems; parity check codes; turbo codes; AWGN multiple access channel; BER; Gaussian approximation; additive white Gaussian noise channel; decoding; factor graph; interleaver-based multiple access system; irregular LDPC code; iterative turbo detection; lDMA system; low-density parity-check code; message probability density function; signature character; Degree profiles; Gaussian approximation; IDMA; LDPC; MAC;
Conference_Titel :
Wireless, Mobile and Multimedia Networks (ICWMNN 2010), IET 3rd International Conference on
Conference_Location :
Beijing
DOI :
10.1049/cp.2010.0631
