Analysis of CDMA-based land mobile satellite communication systems over fading channels

• Main Author: Zhang, Wei
• Other Authors: Kot, Alex Chichung
• Format: Theses and Dissertations
• Language: English
• Published: 2008
• Subjects: DRNTU::Engineering::Electrical and electronic engineering::Satellite telecommunication; DRNTU::Engineering::Electrical and electronic engineering::Wireless communication systems
• Online Access: http://hdl.handle.net/10356/13292
• Institution: Nanyang Technological University

Application of code-division multiple access (CDMA) scheme in mobile satel-lite communication has been widely discussed recently. Low earth orbit (LEO) satellite constellations, which take advantage of a limited link power budget, have also attracted great interest. Among the main problems generated in LEO constellations, severe multipath and shadowing due to low minimum elevation angles should be addressed. Diversity combining, which combines multiple repli-cas of the received signal, can be used to combat multipath impairment. In this thesis, by means of analytical and numerical methods, the average bit error rate of a wideband DS-CDMA land mobile LEO satellite communication sys-tem with an equal-gain RAKE receiver is derived. The author considered an urban channel model, which is a combination of a narrowband model and a wide-band tapped delay line model. An approach was also presented in this thesis for obtaining the approximated average bit error rate, which is computationally simple and efficient. This approach takes advantage of moment parameters of path gain random variables with Rayleigh distribution. The analytical results with BPSK modulation, validated by simulation, are provided to illustrate the achievable performance with both diversity and no-diversity reception. Using measured channel parameters, the performance for various satellite elevation angles is also investigated. It is shown that it is beneficial to use multipath diversity only when the elevation angle is lower than 56 degrees.