Overloaded CDMA systems with displaced binary signatures
EURASIP Journal on Wireless Communications and Networking - Special issue on innovative signal transmission and detection techniques for next generation cellular CDMA systems
EURASIP Journal on Applied Signal Processing
An improved overloading scheme for downlink CDMA
EURASIP Journal on Applied Signal Processing
A class of errorless codes for overloaded synchronous wireless and optical CDMA systems
IEEE Transactions on Information Theory
Overloading cellular DS-CDMA: a bandwidth-efficient scheme for capacity enhancement
ICDCN'08 Proceedings of the 9th international conference on Distributed computing and networking
Errorless codes for over-loaded CDMA with active user detection
ICC'09 Proceedings of the 2009 IEEE international conference on Communications
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Multiple access techniques which allow a communication medium to be shared between different users represent one of the most challenging topics in digital communications. In terms of the number of users that can be accommodated on a given channel, there are two distinct classes of multiple access techniques. The first class includes the well-known FDMA, TDMA, and OCDMA. On a channel whose bandwidth is N times the bandwidth of the individual user signals, these techniques can accommodate N users without any mutual interference, but not a single additional user can be supported beyond this limiting number. The second class includes CDMA with pseudo-noise spreading sequences (which we refer to as PN-CDMA) and some other related schemes. PN-CDMA does not have a hard limit on the number of users that can be accommodated, but is subject to multi-user interference which grows linearly with the number of users. In this article, after reviewing the capacity limits of existing multiple access techniques, we describe some newly introduced concepts which allow us to accommodate N users without any interference while also accommodating additional users at the expense of some SNR penalty