Performance Analysis of Mobile Satellite Noncoherent DS-CDMA Systems with Orthogonal Signals

Yong-Hoon CHO  Jun-Kui AHN  Een-Kee HONG  Keum-Chan WHANG  

IEICE TRANSACTIONS on Communications   Vol.E84-B   No.3   pp.623-633
Publication Date: 2001/03/01
Online ISSN: 
Print ISSN: 0916-8516
Type of Manuscript: PAPER
Category: Satellite and Space Communications
noncoherent DS-CDMA,  mobile satellite communications,  QS-DBPSK,  M-ary orthogonal signaling,  

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As noncoherent direct sequence code-division multiple-access (DS-CDMA) mobile satellite communications, two typical transmission schemes are compared; one is a quasi-synchronous differential BPSK (QS-DBPSK) where orthogonal signals are used for reducing the multiple access interference and the other is M-ary orthogonal signaling (MOS) scheme where orthogonal signals are used for exploiting more efficient modulation. The performances are evaluated in additive white Gaussian noise (AWGN) and shadowed Rician fading (SRF) channels and the effects of timing misalignments in the QS-DBPSK system and the amount of Doppler shifts of a SRF channel are investigated. The results show that MOS much outperforms QS-DBPSK in the region of low system loading up to about 50% and a precise chip synchronization is required for QS-DBPSK. In a SRF channel, it is also shown that QS-DBPSK much outperforms MOS in a slow fading channel but MOS has a performance gain against the large Doppler shift.