An Experimental Adaptive Beamforming System for the IEEE 802.16e-2005 OFDMA Downlink

Abstract

Transmit adaptive beamforming can be applied on the subcarriers of an OFDM system to obtain a coherent processing gain at the receiver. The IEEE 802.16e-2005 standard for mobile broadband wireless access contains signaling strategies that facilitate the use of downlink adaptive beamforming which leverages time-division duplex (TDD) channel reciprocity. Using these strategies, Motorola Labs has developed an experimental mobile multi-antenna OFDM system that implements a real-time, adaptive beamformer. This paper describes key components and parameters of this experimental system and describes the results of initial field experiments that show the performance gains realized by this platform