Code-modulated path-sharing multi-antenna receivers: theory and analysis
IEEE Transactions on Wireless Communications
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IEEE Transactions on Communications
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ICDCN'08 Proceedings of the 9th international conference on Distributed computing and networking
New bounds on the total-squared-correlation of quaternary signature sets and optimal designs
GLOBECOM'09 Proceedings of the 28th IEEE conference on Global telecommunications
Adaptive binary signature design for code division multiplexing
MILCOM'06 Proceedings of the 2006 IEEE conference on Military communications
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We compare the maximum achievable common signal to interference and noise ratio (SINR) target level Kmax in the downlink of various code division multiple access (CDMA) systems with binary sequence sets. We derive an upper bound to Kmax for binary systems with symbol-aligned users, and we compare this upper bound to the value of Kmax for quasi-orthogonal sequences (QOS), Grassmannian signatures and binary Pados-Karystinos signatures. Secondly, we turn our attention to systems where the (binary) signatures of the users are displaced with respect to each other. In this context, we show that the value of Kmax of improved random O(rthogonal)CDMA/OCDMA (O/O) can further be increased as compared to the original improved. O/O system (with square-root cosine rolloff pulses) by an appropriate choice of the chip pulse. In addition to this, improved O/O systems with fixed signature set can achieve values of K max that are as high as those in the improved random O/O system, while not having the drawback of a spread on Kmax. Applying a steepest descent search to such a fixed improved O/O system, can result in a system with a binary signature set that has even higher values for Kmax well beyond the upper bound on Kmax for systems with aligned chip pulses