Performance limits for multi-user decorrelating detectors in DS-CDMA cellular radio systems

The use of conventional matched filter detectors for CDMA systems is common, but known to be suboptimum. Performance improvements can be brought about through the use of multi-user detection techniques. A class of these, decorrelation detectors, are considered. A description of both conventional and decorrelating receivers is given, and the problem of 'noise amplification' explained. An analytic equation for this is then introduced and used to obtain comparative capacity estimates for a range of system parameters. The 'partial decorrelator' is then introduced and shown to offer better performance and lower complexity in certain situations. Finally, the effects of data modulation are discussed along with possible techniques to deal with them.