Inexpensive upgrade of base-station dumb antennas by two magnetic loops for "blind" adaptive downlink beamforming
Kainam Thomas Wong, A.K.Y. Lai · IEEE Antennas and Propagation Magazine · 2005
A simple scheme is herein proposed to upgrade an older base-station's "dumb" antennas for use in an adaptive space-division frequency-reuse downlink, with no expensive retrofitting of each "dumb" antenna with its own rake receiver. This scheme adds only two horizontally oriented loops (plus an optional vertically oriented dipole) to a base station's 120/spl deg/-azimuth sector, each with a temporal (not space-time) rake receiver. Such a pair (or triad) of diversely polarized but collocated antennas can estimate an incident mobile-source's uplink direction of arrival, based on which the existing "dumb" antennas can beam-form towards the mobile in downlink transmission.