Field data showing the downlink adaptive beamforming gains in an experimental IEEE 802.16e-2005 OFDMA system

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 beam- forming which leverages time-division duplex (TDD) channel reciprocity. Motorola Labs has developed an experimental mobile multi-antenna OFDM system that implements a realtime, adaptive beamformer that uses these strategies. This paper describes key components and parameters of this experimental system and describes the results of field experiments that show the performance gains realized by this platform.