Department of Electrical & Computer Engineering,University of Tehran
In this paper, the application of regular Low-Density Parity-Check(LDPC) codes in Multi-Carrier Frequency-Hopping (MC-FH) CDMA systems is studied. To this end, different well-known constructions of regular LDPC codes are considered and the performance of LDPC coded MC-FH-CDMA systems, based on these constructions, are evaluated and compared in a frequency-selective slowly Rayleigh fading channel. These results are compared with those previously reported for super-orthogonal convolutionally coded MC-FH-CDMA systems. The simulation results indicate that the LDPC coded MC-FH-CDMA system significantly outperforms the uncoded and super-orthogonal convolutionally coded schemes. To alleviate the restrictions imposed by well known LDPC construction methods when applied to the coded MC-FH-CDMA system considered, a new semi random construction is proposed and its performance is evaluated in the coded scheme. The simulation results indicate that this new construction substantially outperforms other well-known construction methods in the application considered.