Space-Time Filtering for Parallel-Channel Reuse in UMTS Downlink Transmission

Abstract

In this paper we investigate limitations facing high rate transmission in the downlink of UMTS systems. A solution is proposed based on space-time filtering to allow parallel channel transmission and spreading code reuse. The optimum receiver is derived taking into consideration non-ideality in space-time filtering caused by channel estimation errors. Comparisons with ordinary CDMA receivers, based on dispreading the received sequence with the same code used for transmission, show significant performance enhancement in system capacity, especially at large number of utilized parallel channels and in the presence of high channel estimation errors.