Performance Analysis of QS-CDMA Systems

In the paper, the performance of quasi-synchronous CDMA (QS-CDMA) system, which can allow an increased timing error in synchronized access, is discussed. Average BER performance of the system is analyzed in the condition of different access timing error and different asynchronous users by simulation in AWGN channel. The results show that QS-CDMA system is shown to have great performance gain over the asynchronous system when access timing error is within a few chips and asynchronous users is tolerable. However, with access timing error increasing and asynchronous users increasing, the performance of QS-CDMA will degrade. Also, we can determine the number of tolerable asynchronous users for different access timing error by simulation figures.

Authors:

• Cuiran Li
• Jianli Xie
• Chengshu Li

Keywords:

• Code-division multiple access
• Quasi-SynchronousCDMA
• Access timing error

References:

[1] C.Onan, O. Kucur, and E. Ozturk, "Performance of quasi-synchronous
scale-time-code division multiple access system over the additive white
Gaussian noise channel", IEEE Signal Processing and Communications
Applications Conference, pp.708-711, April 2004.
[2] A. Kuramoto, T. Abrao, and P. J. Jeszensky. "Sets of sequences for
QS-CDMA systems with interference cancellation over multipath
Rayleigh fading channels", IEEE Eighth International Symposium on
Spread Spectrum Techniques and Applications, pp.694-698, Sep. 2004.
[3] J. K. Kyeong, R. A. Iltis, "Joint detection and channel estimation
algorithms for QS-CDMA signals over time-varying channels", IEEE
Trans.on Commun., Vol.50, pp. 845-855, May 2002.
[4] S. Cioni, G. D. Gaudenzi, and R. Rinaldo, "Adaptive coding and
modulation for the reverse link of broadband satellite networks", IEEE
GLOBECOM '04, Vol.2, pp. 1101-1105, Dec. 2004.
[5] F. Pingzhi, "New direction in spreading sequence design and the related
theoretical bounds", IEEE International Conference on Communications,
Circuits and Systems and West Sino Expositions, Vol.1, pp. xliii - xlviii,
July 2002
[6] S. H. Duan. "Researches on Quasi-Synchronous CDMA and Its
Application in Mobile Satellite Communication System". Harbin Industry
University, 2001.
[7] L. Biqi; Z. Ping, H.Jiandong, "A generalized QS-CDMA system and the
design of new spreading codes", IEEE Trans.on VTC, Vol. 47, pp.12687-
1275, Nov.1998
[8] S. Stanczak, A. Feistel, "Dynamic resource allocation for
frequency-selective orthogonal QS-CDMA channels", IEEE Conference
on Signals, Systems and Computers, Vol. 1, pp.632-636.2004
[9] J. K. Kyeong, R. A. Iltis, "Block coded modulation for the QS-CDMA
system", IEEE Conference on Signals, Systems and Computers, Vol. 1,
pp.9-12, Nov. 2003
[10] D. V. Sarwate, "Mean-Square Correlation of Shift-Register Sequence",
IEE Proceedings.1984,131(2):101-106.