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Dual diversity performance of direct sequence code division multiple access systems over low earth orbit satellite channel.

Author(s)
Abdul Waheed Umrani Electrical Electronic Engineering, Nanyang Technological University, Singapore
V. K. Dubey Electrical Electronic Engineering, Nanyang Technological University, Singapore
Bhawani Shankar Chowdhry Department of Electronic, Telecommunication & Biomedical Engineering, Mehran University of Engineering & Technology, Jamshoro, Pakistan
Abstract
CDMA (Code Division Multiple Access) is the predominant multiple access technique proposed for the 3G (Third Generation) wireless Communications systems worldwide. In this paper, the down-link of a LEO (Low Earth Orbit) satellite communication system employing power controlled DS (Direct Sequence) CDMA with dual satellite diversity is analyzed and its performance is computed in terms of BER (Bit Error Rate).The system performance evaluated using quasi-analytic method has been thoroughly validated by means of extensive Monte-Carlo simulations. The effect of MAI (Multiple Access Interference) on the performance is investigated with a new power control technique. We consider two cases depending upon the location of mobile user. The quantitative results tend to indicate that dual diversity improves the system performance provided that optimal power control scheme is employed. It is proposed that 1) no power control should be exercised when a mobile user is shadowed to only one satellite, and smaller value of P (power amplification factor) should be chosen for the user shadowed to both satellites in dual-diversity case. Such an approach would also minimize the excess MAI due to open power control mechanism 2). An optimum value of power amplification factor should be chosen which provides acceptable performance in both cases considered. In our simulation such value is P=5, when dual satellite diversity employed.
Publication Details
Page(s) 145-156
DOI DOI not available
Published Journal: Mehran University Research Journal of Engineering and Technology, Volume: 23, Issue: 3, Year: 2004

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