An Efficient Dual-Channel Synchronisation Scheme for the Return Link of CDMA Mobile Satellite Systems


IEICE TRANSACTIONS on Fundamentals of Electronics, Communications and Computer Sciences   Vol.E79-A   No.12   pp.2050-2061
Publication Date: 1996/12/25
Online ISSN: 
Print ISSN: 0916-8508
Type of Manuscript: Special Section PAPER (Special Secton on Spread Spectrum Techniques and Applications)
satellite communications,  DS-CDMA,  synchronisation,  

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In the envisaged Universal Mobile Telecommunications System (UMTS), the satellite component will have to provide services to mobile or, in some cases, hand held terminals with a required grade of user co-operation and link availability in various communication environments. This may require the capability of the satellite link to cope with more severe multipath environments than those for which mobile satellite links are most frequently designed (maritime or open rural applications); unfortunately, when the mobile radio channel is affected by multipath and a coherent demodulation is chosen, the phase synchronisation can be a critical issue. To satisfactorily deal with the arising difficulties, a dual channel demodulation is a viable and efficient strategy for the forward link, since only one common pilot channel is needed in this case. If the same dual channel demodulation is considered for the return link, an unacceptable capacity reduction may result. In this paper, some synchronisation strategies are analysed and an efficient dual channel demodulation scheme is proposed for the return link of a satellite DS-CDMA mobile communication system; furthermore, the impact on the overall system performance or capacity is analysed.