Performance evaluation of adaptive chip-level channel equalizers in WCDMA downlink

The most important 3rd generation cellular communications standard is based on wideband CDMA (WCDMA). Receivers based on TDMA style channel equalization at the chip-level have been proposed for a WCDMA downlink employing long spreading sequences to ensure adequate performance even with a high number of active users. These receivers equalize the channel prior to the despreading, thus restoring the orthogonality of users and resulting in multiple access interference (MAI) suppression. In this paper four adaptive versions of chip-level channel equalizers are studied and their performance is evaluated in a Rayleigh fading multipath channel. The numerical results show a significant performance improvement over the conventional RAKE receiver with a large number of active users.