Asynchronous CDMA Systems with Random Spreading–Part II: Design Criteria

Laura Cottatellucci (1) , Ralph Müller (2) , Merouane Debbah (3)

1 Eurecom [Sophia Antipolis]
2 IES NTNU - Department of Electronic Systems [Trondheim]
3 E3S - Supélec Sciences des Systèmes

Totally asynchronous code-division multiple-access (CDMA) systems are addressed. In Part I, the fundamental limits of asynchronous CDMA systems are analyzed in terms of spectral efficiency and SINR at the output of the optimum linear detector. The focus of Part II is the design of low-complexity implementations of linear multiuser detectors in systems with many users. We consider detectors that admit a multistage representation, e.g. reduced rank multistage Wiener filters, polynomial expansion detectors, weighted linear parallel interference cancellers. The effects of excess bandwidth, chip-pulse shaping, and time delay distribution on CDMA with suboptimum lin- ear receiver structures are investigated. Recursive expressions for universal weight design are given. The performance in terms of SINR is derived in the large-system limit and the performance improvement over synchronous systems is quantified. The considerations distinguish between two ways of forming discrete-time statistics: chip-matched filtering and oversampling.

Domaines: Réseaux et télécommunications [cs.NI]

Laura Cottatellucci, Ralph Müller, Merouane Debbah. Asynchronous CDMA Systems with Random Spreading–Part II: Design Criteria. IEEE Transactions on Information Theory, 2010, 56 (4), pp.1498-1520. ⟨10.1109/TIT.2010.2040898⟩. ⟨hal-00556129⟩