Multi carrier code division multiple access (MC-CDMA) system is a promising multi carrier modulation (MCM) technique for high data rate wireless communication over frequency selective fading channels. MC-CDMA system is a combination of code division multiple access (CDMA) and orthogonal frequency division multiplexing (OFDM). The OFDM parts reduce multipath fading and inter symbol interference (ISI) and the CDMA part increases spectrum utilization. Advantages of this technique are its robustness in case of multipath propagation and improve security with the minimize ISI. Nevertheless, due to the loss of orthogonality at the receiver in a mobile environment, the multiple access interference (MAI) appears. The MAI is one of the factors that degrade the bit error rate (BER) performance of MC-CDMA system. The multiuser detection (MUD) and turbo coding are the two dominant techniques for enhancing the performance of the MC-CDMA systems in terms of BER as a solution of overcome to MAI effects. In this paper a low complexity iterative soft sensitive bits algorithm (SBA) aided logarithmic-Maximum a-Posteriori algorithm (Log MAP) based turbo MUD is proposed. Simulation results show that the proposed method provides better BER performance with low complexity decoding, by mitigating the detrimental effects of MAI.
Recent innovations in wireless technology have made a need to propose hybrid systems to achieve excellent data rates and performance. One such system is multi-carrier code division multiple access (MC-CDMA), a combination of direct sequence code division multiple access (DS-CDMA) and orthogonal frequency division multiplexing (OFDM) systems. It offers high data rate, flexible bandwidth allocation and enhanced performance to each user simultaneously. Owing to these advantages, this system is chosen to be interfaced with the physical layer of software defined radio (SDR). SDR is defined as a reprogrammable hardware that suits emerging standards of next generation wireless communication. In MC-CDMA system, when the orthogonality is not maintained in the OFDM part, it leads to multiple access interference (MAI). To overcome the effects of MAI and to reduce complex detection to a great extent, super orthogonal turbo codes is chosen for the system. In this paper, MC-CDMA based SDR system is constructed using super orthogonal turbo codes with log-MAP algorithm. The simulation results show that the performance is remarkable when compared to a turbo system using recursive systematic codes (RSC). The BER performance of both the systems is analyzed for different iterations.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.