Quasi-Large Sparse-Sequence CDMA: Approach to Single-User Bound by Linearly-Complex LAS Detectors

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dc.creatorSun, Yi
dc.date2008-02-23
dc.date.accessioned2026-07-07T09:22:54Z
dc.date.available2026-07-07T09:22:54Z
dc.descriptionWe have proposed a quasi-large random-sequence (QLRS) CDMA where K users access a point through a common channel with spectral spreading factor N. Each bit is extended by a temporal spreading factor B and hopped on a BN-chip random sequence that is spread in time and frequency. Each user multiplexes and transmits B extended bits and the total channel load is alpha = K/N bits/s/Hz. The linearly-complex LAS detectors detect the transmitted bits. We have obtained that as B tends to infinity, if alpha < 1/2 - 1/(4ln2), each transmitted bit achieves the single-bit bound in BER in high SNR regime as if there was no interference bit. In simulation, when bit number BK >= 500, each bit can approach the single-bit bound for alpha as high as 1 bit/s/Hz. In this paper, we further propose the quasi-large sparse-sequence (QLSS) CDMA by replacing the dense sequence in QLRS-CDMA with sparse sequence. Simulation results show that when the nonzero chips are as few as 16, the BER is already near that of QLRS-CDMA while the complexity is significantly reduced due to sequence sparsity.
dc.descriptionCISS 2008
dc.identifierhttps://arxiv.org/abs/0802.3429
dc.identifierhttp://arxiv.org/abs/0802.3429
dc.identifier.urihttp://salesiana.dossiersoluciones.com/handle/123456789/155543
dc.subjectInformation Theory
dc.titleQuasi-Large Sparse-Sequence CDMA: Approach to Single-User Bound by Linearly-Complex LAS Detectors
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