Code-Time Diversity for Direct Sequence Spread Spectrum Systems
Wireless Personal Communications • 2015
Publication Information
Authors
A. Y. Hassan
Keywords
Direct sequence spread spectrum Time diversity Code diversity Maximal ratio combiner Inter-symbol interference Single-input and single-output systems Multiple-input and multiple-output systems Rayleigh fading channel
Journal
Wireless Personal Communications
Publisher
Springer
Volume
84
Issue
1
Pages
695-718
publication.type
International
Paper Link
Open Link
Supplementary Materials
Not Available
Abstract
Time diversity is achieved in direct sequence spread spectrum by receiving different faded delayed copies of the transmitted symbols from different uncorrelated channel paths when the transmission signal bandwidth is greater than the coherence bandwidth of the channel. In this paper, a new time diversity scheme is proposed for spread spectrum systems. It is called code-time diversity. In this new scheme, N spreading codes are used to transmit one data symbol over N successive symbols interval. The diversity order in the proposed scheme equals to the number of the used spreading codes N mul- tiplied by the number of the uncorrelated paths of the channel L. The paper represents the transmitted signal model. Two demodulators structures will be proposed based on the received signal models from Rayleigh flat and frequency selective fading channels. Probability of error in the proposed diversity scheme is also calculated for the same two fading channels. Finally, simulation results are represented and compared with that of maximal ration combiner and multiple-input and multiple-output systems.
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