Spatial equivalence classes for CDMA array processing

Abstract

We consider the reverse link of a cellular direct sequence CDMA system with the aim of increasing the system's capacity. The capacity of a conventional (matched filter) receiver can be increased by employing sectorized antenna arrays or multiuser detection techniques. Our results confirm that the potentially complex approach of beamforming followed by multiuser detection further increases capacity. To reduce complexity, bit detection techniques based on partitioning the users into spatial equivalence classes by beamforming and then employing standard multiuser detection techniques within each class are investigated. Subtractive interference cancellation yields the lowest bit error ratios and is the least computationally complex method of multiuser detection under consideration.