Simulation Studies of Channel Coded MSK in Wireless Environment

Abstract

The Low-Density Parity-Check codes are among the most powerful forward error-correcting codes and are poised to become a standard in the next digital transmission system generations. In addition to their error correction capacity, the LDPC codes have a relatively simple decoding algorithm, so they are likely to be the coding choice in future. In 2003, LDPC codes beat all other competing codes to become the error correcting code in the new DVB-S2 standard for the satellite transmission of digital television. In this thesis an attempt has been made to further improve the error performance of LDPC codes by combining them with two of the most powerful modulation techniques, MSK and GMSK. The performance of LDPC coded MSK/GMSK modulated signals is tested over fading conditions ranging from very severe to moderate. The Nakagami fading conditions have been modeled by simulating the fading envelope. This adaptive fading model has been used to generate various fading conditions for testing the BER performance of LDPC codes. In this thesis, a comparative study of LDPC coding using MSK and GMSK modulation has also been done. The proposed system when compared with the uncoded system provides a coding gain of 3.3 dB for m=1 and it is 4.5 dB for m=2 for MSK and 3.9dB for m=1 and 5dB for m=2 for GMSK. It is also shown that for a given BER, LDPC coded signal requires less SNR when compared to uncoded signal.