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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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MC-CDMA system model.
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pone.0115710.g001: MC-CDMA system model.

Mentions: A coded MC-CDMA system, with ‘K’ users assuming perfect frame synchronization is shown in Fig. 1. The information bits b(k) of the kth user is encoded using a convolutional encoder. The coded bit of the kth user at the tth time interval is then spread by a PN sequence and transmitted using MC-CDMA, where the total number of subcarriers is equal to the length of the signature sequence L. At the receiver, channel responses of the subcarriers are independent, the signal of each user is despread and maximum ratio combining (MRC) in the frequency domain is performed.


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

Kumaravel R, Narayanaswamy K - PLoS ONE (2015)

MC-CDMA system model.
© Copyright Policy
Related In: Results  -  Collection

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

pone.0115710.g001: MC-CDMA system model.
Mentions: A coded MC-CDMA system, with ‘K’ users assuming perfect frame synchronization is shown in Fig. 1. The information bits b(k) of the kth user is encoded using a convolutional encoder. The coded bit of the kth user at the tth time interval is then spread by a PN sequence and transmitted using MC-CDMA, where the total number of subcarriers is equal to the length of the signature sequence L. At the receiver, channel responses of the subcarriers are independent, the signal of each user is despread and maximum ratio combining (MRC) in the frequency domain is performed.

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