Reduced-Rank Adaptive Filtering Using Localized Processing for CDMA Systems
An integrated beamforming (spatial processing) and multiuser-detection (temporal processing) scheme is an effective approach to increase system capacity but is also impractical due to the high associated computational costs. To overcome this problem, researchers have developed reduced-rank approaches. Adding to this class of algorithms, this paper introduces a joint-domain adaptive algorithm, which processes spatial and temporal data within a localized region after transformation to a "Beamspace." This new Joint-Domain-Localized (JDL) adaptive algorithm is developed for single-cell uplink Code-Division Multiple-Access (CDMA) systems with a receive-antenna array. Given a rank constraint on the JDL transformation, this paper develops the optimal choice of transformation matrix and justifies a simpler suboptimal choice.