Asynchronous CDMA systems with random spreading-part II: design criteria

Totally asynchronous code-division multiple-access (CDMA) systems are addressed. In part I, the fundamental limits of asynchronous CDMA systems were analyzed in terms of total capacity 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 that admit a multistage representation, e.g. reduced rank multistage Wiener filters, polynomial expansion detectors, weighted parallel interference cancellers. The effects of the excess bandwidth, chip-pulse shaping, and time delay distribution on CDMA with suboptimum linear 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: chipmatched filtering and over...

• Type: Journal
• Year: 2010
• Where: TIT
• Authors: Laura Cottatellucci, Ralf R. Müller, Mérouane Debbah
• Keywords: Asynchronous Cdma Systems, CDMA, Education, Optimum Linear Detector, TIT 2010