Multistage DS-CDMA receivers with pathwise interference mitigation

We investigate the application of multiple stage filters in the context of pathwise processing. Pathwise processing proposes to overcome one of the major difficulties encountered with linear DS-CDMA receivers in time-varying multipath propagation, namely the estimation of a large number of parameters from scarce training data. Pathwise interference estimation allows the separation of the parameters into rapidly and slowly varying parameters, thereby allowing the scarce training data to be used in the estimation of the rapidly varying parameters with a short time constant while the slowly varying parameters can be estimated over a much larger time interval. This paper focuses on the application of polynomial expansion (PE) filters to pathwise processing and proposes the use of a weighting factor per signal component. We show that these weighting coefficients not only achieve significant improvements in the presence of power imbalances between users and paths w.r.t. scalar weighting, but also achieve further improvement due to the better estimation of the rapidly varying parameters.