Authors : A.Shanmugam , A. R. Abdul Rajak and P.Anitha
Abstract: Wireless networks are backbone to the broadband communication in multimedia services. It uses the OFDM/CDMA a multi carrier transmission technique which has gained interest for applications in future wireless communication systems (4G systems).In OFDM/CDMA systems, the advantages of OFDM and CDMA techniques are combined to achieve enhanced performance. One of the main advantages of OFDM is, its ability to modulate a wide-band signal into a large number of orthogonal sub-carriers with narrow band signal components avoiding frequency-selective fading on each sub-carrier. However, multipath fading phenomenon of the wireless radio channel causes significant BER performance degradation. So channel coding using efficient forward Error Correction (FEC) schemes has to be employed. This paper provides solution to the problem by using concatenated coding schemes for FEC. In this paper, a new concatenated coding scheme using turbo and irregular turbo codes has been proposed. Performance comparison has been made between the BER un-coded and coded CDMA network with OFDM system. Simulation results show that there is significant improvement in BER performance when channel coding using turbo and irregular turbo codes have been employed and the concatenated coding scheme using turbo and irregular turbo code gives better performance.
A.Shanmugam , A. R. Abdul Rajak and P.Anitha , 2005. Optimal Fec Scheme for Wireless CDMA Networks with OFDM Transceiver . Asian Journal of Information Technology, 4: 550-557.