J.Ravindrababu, E.V.Krishna Rao



Performance improvement in Multistage Multiuser DS-CDMA system over Rayleigh fading channel

pdf PDF



Direct Sequence Code Division Multiple Access (DS-CDMA) system is well known wireless technology. Multiple Access Interference (MAI) is a major problem in DS-CDMA system caused by its users. When the number of users increases the system performance gradually decreases especially in fading environment. In this paper, multistage multiuser detection techniques were introduced to detect the users data in presence of MAI. Multistage Multiuser Parallel Interference Cancellation (PIC) technique gives good performance but biased decision statistic problem is raised due to imperfect estimation of MAI as number of stages increases. To overcome biased decision statistic problem by Multistage Multiuser Partial Parallel Interference Cancellation (PPIC) technique is used to reduce the MAI partially stage by stage. But the problem is in PIC and PPIC computational complexity is very high when the number of stages increases. The computational complexity is minimized by using Multistage Difference PIC (DPIC) detection technique is based on the convergence nature of interference cancellation. Multistage Multiuser Partial Differencing Parallel Interference Cancellation (PDPIC) Technique is the combination of Difference PIC and Partial PIC. By using technique, Performance improved and computational complexity is minimized both are performed at a time. Simulation results shows that the partial difference PIC better performed (in terms of Bit Error Rate (BER)) than PIC and PPIC in fading environment.



Multiuser detection, MAI, PIC, PPIC, DPIC, PDPIC, Rayleigh channel



[1] J.Ravidrababu,E.V.Krishna Rao and Y.Raja Rao. “Interference and complexity reduction in multistage multiuser detection in DSCDMA” Springer: wireless personal communications, Vol-79, pp1385-1400, November 2014.

[2] D. Middleton and A. D. Spaulding, “Elements of weak-signal detection in non-Gaussian noise,” in Advances in Statistical Signal Processing -Vol. 2: Signal Detection, H. V. Poor and J. B. Thomas, Eds. Greenwich, CT: JAI Press, 1993.

[3] K. L. Blackard, T. S. Rappaport, and C.W. Bostian, “Measurements and models of radio frequency impulsive noise for indoor wireless communications,” IEEE J. Select. Areas Commun., vol. 11, pp. 991–1001, Sept. 1993.

[4] T. K. Blankenship, D. M. Krizman, and T. S. Rappaport, “Measurements and simulation of radio frequency impulsive noise in hospitals and clinics,” in Proc. 1997 IEEE Veh. Technol. Conf., 1997, pp. 1942–1946.

[5] D. Middleton, “Channel modeling and threshold signal processing in underwater acoustics: An analytical overview,” IEEE J. Oceanic Eng.,vol. OE-12, pp. 4–28, Jan. 1987.

[6] B. Aazhang and H. V. Poor, “Performance of DS/SSMA communications in impulsive channels—Part I: Linear correlation receivers,” IEEE Trans. Commun., vol. COM–35, pp. 1179–1188, Nov. 1987.

[7] H. V. Poor, “Non-Gaussian signal processing problems in multiple-access communications,” presented at the 1996 USC/CRASP Workshop on Non-Gaussian Signal Processing, Ft. George Meade, MD, May 1996.S.Verdu, “Multiuser Detection”, Cambridge University Press. 1998.

[8] H. V. Poor and M. Tanda, “Multiuser detection in impulsive channels,” Annales des Telecommun, vol. 54, pp. 392–400, July/Aug. 1999.

[9] X. Wang and H. V. Poor, “Robust multiuser detection in non-Gaussian channels,” IEEE Trans. Signal Processing, vol. 47, pp. 289–305, Feb.1999.

[10] H. V. Poor and M. Tanda, “On Mestimator- based multiuser detection in non- Gaussian noise,” in Proc. 3rd Eur. Personal Mobile CommunicationsConf., Paris, France, Mar. 1999, pp. 139–142.

[11] J.Ravidrababu and E.V.Krishna Rao. “Performance Analysis and comparison of Linear Multi-User Detectors in DS-CDMA system” International journal of electronics and communication engineering & technology. Vol-3, issue 1, January-June 2012, pp.229-243.

[12] Rajagopal, S.Bhashyam ,R.Cavallaro and B.A azhang "Real Time Algorithms and Architectur es for Multiuser Channel Estimation and Detection in Wireless Base- Station Receivers", IEEE Transactions on Wireless Comm., Vol.1, No.3, July 2002.

[13] J.Ravidrababu and E.V.Krishna Rao. “Performa nce Analysis and comparison of spreading codes in Linear Multi- User Detectors for DS- CDMA system” WSEAS transactions on communications. Issue 11, vol 11, November- 2012.

[14] J.Ravidrababu and E.V.Krishna Rao. “Performa nce Analysis , improvement and complexity red uction in Multistage Multi user detector with par allel interference cancellation for DS-CDMA S ystem Using odd kasami sequence WSEAS trans actions on communications, Issue 4, vol-12, April 2013. 

Cite this paper

J.Ravindrababu, E.V.Krishna Rao. (2017) Performance improvement in Multistage Multiuser DS-CDMA system over Rayleigh fading channel. International Journal of Communications, 2, 68-76


Copyright © 2017 Author(s) retain the copyright of this article.
This article is published under the terms of the Creative Commons Attribution License 4.0