Multiuser Detection
A class of errorless codes for overloaded synchronous wireless and optical CDMA systems
IEEE Transactions on Information Theory
Random sequence multisets for synchronous code-division multiple-access channels
IEEE Transactions on Information Theory
Spectral efficiency of CDMA with random spreading
IEEE Transactions on Information Theory
Multiuser detection for overloaded CDMA systems
IEEE Transactions on Information Theory
Multiuser Detection in a Dynamic Environment– Part I: User Identification and Data Detection
IEEE Transactions on Information Theory
Multi-user detection for DS-CDMA communications
IEEE Communications Magazine
Extending the capacity of multiple access channels
IEEE Communications Magazine
A class of errorless codes for overloaded synchronous wireless and optical CDMA systems
IEEE Transactions on Information Theory
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In this paper we introduce a new class of codes for Over-loaded synchronous wireless CDMA systems which increases the number of users for a fixed number of chips without introducing any errors. In addition these codes support active user detection. We derive an upper bound on the number of users with a fixed spreading factor. Also we propose an ML decoder for a subclass of these codes that is computationally implementable. Although for our simulations we consider a scenario that is worse than what occurs in practice, simulation results indicate that this coding/decoding scheme is robust against additive noise. As an example, for 64 chips and 88 users we propose a coding/decoding scheme that can obtain an arbitrary small probability of error which is computationally feasible and can detect active users. Furthermore, we prove that for this to be possible the number of users cannot be beyond 230.