Low-complexity smart antenna methods for third-generation W-CDMA systems

There is still an open debate within the research community regarding the l ikely performance enhancement of smart antennas versus their complexity for commercial wireless applications. The goal of the study presented in this paper is to investigate the performance improvement attainable using relati vely, simple smart antenna techniques when applied to the third-generation W-CDMA air interface. Methods to achieve this goal include fixed multibeam architectures with different beam selection algorithms (maximum power crite rion, combined beams) or adaptive solutions driven by relatively simple dir ection finding algorithms, After comparing these methods against each other for several representative scenarios, some issues related to the sensitivi ty of these methods are also studied, (e.g., robustness to environment, mis matches originating from implementation limitations, etc.). Results indicat e that overall, conventional beamforming seems to be the best choice in ter ms of balancing the performance and complexity requirements, in particular when the problem with interfering high-bit-rate W-CDMA users is considered.