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Performance enhancement of MC-CDMA system through novel sensitive bit algorithm aided turbo multi user detection.

Kumaravel R, Narayanaswamy K - PLoS ONE (2015)

Bottom Line: The OFDM parts reduce multipath fading and inter symbol interference (ISI) and the CDMA part increases spectrum utilization.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.Simulation results show that the proposed method provides better BER performance with low complexity decoding, by mitigating the detrimental effects of MAI.

View Article: PubMed Central - PubMed

Affiliation: Department of Information Technology, Sri Venkateswara College of Engineering, Pennalur-602117, Sriperumbudur, India.

ABSTRACT
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.

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Performance comparison of SOVA, Log MAP and SBA aided Log MAP at Iteration 10.
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pone.0115710.g013: Performance comparison of SOVA, Log MAP and SBA aided Log MAP at Iteration 10.

Mentions: Fig. 13 show that the BER performance comparison of the SOVA, Log MAP and SBA aided Log MAP algorithm for iteration 10 over AWGN channel and Rayleigh channel respectively. It is witnessed that the SBA aided Log MAP turbo MUD achieve excellent performance on both channels at iteration 10. Further it is observed the BER performance of SBA aided Log MAP turbo MUD over Rayleigh channel perform much better than Log MAP based turbo MUD. In Figs. 3, 4, 9, 12, and 13, it seems that the output of the SOVA algorithm is significantly more noisy than those from the Log MAP algorithm due to less robust modulations, coding schemes, channel reliability factor and also poor error correction performance [10–11]. It reveals that the SOVA algorithm curves can bring slight BER degradation in its error correction capacity, especially when high code rates and high SNR. This will be corrected further decoding iterations increase or by selecting the low code rates.


Performance enhancement of MC-CDMA system through novel sensitive bit algorithm aided turbo multi user detection.

Kumaravel R, Narayanaswamy K - PLoS ONE (2015)

Performance comparison of SOVA, Log MAP and SBA aided Log MAP at Iteration 10.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4340792&req=5

pone.0115710.g013: Performance comparison of SOVA, Log MAP and SBA aided Log MAP at Iteration 10.
Mentions: Fig. 13 show that the BER performance comparison of the SOVA, Log MAP and SBA aided Log MAP algorithm for iteration 10 over AWGN channel and Rayleigh channel respectively. It is witnessed that the SBA aided Log MAP turbo MUD achieve excellent performance on both channels at iteration 10. Further it is observed the BER performance of SBA aided Log MAP turbo MUD over Rayleigh channel perform much better than Log MAP based turbo MUD. In Figs. 3, 4, 9, 12, and 13, it seems that the output of the SOVA algorithm is significantly more noisy than those from the Log MAP algorithm due to less robust modulations, coding schemes, channel reliability factor and also poor error correction performance [10–11]. It reveals that the SOVA algorithm curves can bring slight BER degradation in its error correction capacity, especially when high code rates and high SNR. This will be corrected further decoding iterations increase or by selecting the low code rates.

Bottom Line: The OFDM parts reduce multipath fading and inter symbol interference (ISI) and the CDMA part increases spectrum utilization.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.Simulation results show that the proposed method provides better BER performance with low complexity decoding, by mitigating the detrimental effects of MAI.

View Article: PubMed Central - PubMed

Affiliation: Department of Information Technology, Sri Venkateswara College of Engineering, Pennalur-602117, Sriperumbudur, India.

ABSTRACT
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.

Show MeSH