Rapid Estimation for Spreading Functions of Multipath CDMA Wireless Communication Channels

ALSHEHRI, ABDULLAH ALI

doi:10.21608/mjeer.2008.65211

Rapid Estimation for Spreading Functions of Multipath CDMA Wireless Communication Channels

Document Type : Original Article

Author

ABDULLAH ALI ALSHEHRI

Assistant Professor, Department of Electrical Engineering, Jeddah College of Technology, Jeddah KSA

10.21608/mjeer.2008.65211

Abstract

In this paper, we present a robust and fast computational algorithm for estimating the spreading function of multipath CDMA wireless communication channels in multi-user Direct Sequence Spread Spectrum (DSSS) communication systems. Transmission channels spread the message signals in time and frequency and are typically modeled as random, time-varying systems. The proposed algorithm is to provide a time-frequency dependent windows that can be computed priori to estimate the spreading function of multipath wireless communications channels. Computing such windows priori at the receiver will reduce a significant amount of computational load and to improve the previous proposed channel estimation work. It is shown that the estimation of the parameters of such models is possible by means of the spreading function which is obtained from the discrete time-frequency evolutionary kernel of the received signal using the discrete evolutionary transformation DET.

Keywords

References

[1] G. Proakis and M. Salehi, Communication Systems Engineering, Prentice Hall, 1994.

[2] P. A. Bello, “Characterization of randomly time-variant linear channels,” IEEE Trans. Comm. Systems, pp. 360–393, Dec. 1963.

[3] M.D. Hahm, Z. I. Mitrovski, and E. L. TitlebaumB, “Deconvolution in the presence of Doppler with application to specular multipath parameter estimation,” IEEE Trans. Sig. Proc., vol. 45, No. 9, pp. 2203–2219, Sep. 1997.

[4] S. M. Kay and S. B. Doyle, “Rapid estimation of the range-Doppler scattering function,” IEEE Trans. Sig. Proc., pp. 255–268, Jan. 2003.

[5] L. F. Chaparro and A. A. Alshehri, “Channel modeling for spread spectrum via evolutionary transform,” in Proc. IEEE ICASSP-04, May 2004, pp. 2821–2824.

[6] R. Suleesathira, L. F. Chaparro, and A. Akan, “Discrete Evolutionary Transform for time-frequency analysis,” J. of Franklin Institute, vol. 337, pp. 347–364, Jul.2000.

[7] N. C. Huang and J. K. Aggarwal, “Synthesis and implementation of recursive linear shift-variant digital filters,” IEEE Trans. on Circuits and Systems, vol. 30, no. 1, pp. 29–36, Jan. 1983.

[8] L. F. Chaparro and A. A. Alshehri, “Jammer excision in spread spectrum communications via wiener masking and frequency-frequency evolutionary transform,” in Proc. IEEE ICASSP-03, April 2003, vol. 4, pp. 473–476.

[9] A. A. Alshehri, L. F. Chaparro, and A. Akan, “Evolutionary wiener mask receiver for multiuser direct sequence spread spectrum,” in Proc. EUSIPCO-2005, Sep. 2005.