Symbol level equalizer-based receiver for downlink MAI suppression in CDMA systems

In this paper, a type of symbol-level adaptive equalizer-based receiver is proposed for downlink multiple access interference (MAI) suppression in WCDMA cellular systems. This type of receiver does not need channel estimation, which is necessary in most other proposals, and hence has relative low complexity. After introducing the loop structure of the basic MAI suppression receiver, the paper further proposes a practical modification to improve performance in time-varying and low signal-to-noise ratio (SNR) environments. This modified receiver is called precombining adaptive-order receiver. The performance enhancement owes to multipath pre-combining which increases and smoothes SNR variation of input signal and the adaptive order adjustment which optimizes the equalizer length in terms of channel conditions. The receiver structures are described and represented mathematically. The performances are evaluated by computer simulation and compared to each other as well as to current used Rake receiver . Index Terms — Equalization, Downlink, MAI suppression, WCDMA.