Abstract
This paper presents evolution of beam pattern of an Adaptive transmit beamspace
beamformer(ATBBF) at the base station of a 3rd generation code division multiple access (3G-CDMA)
system for Multiple input single output (MISO) per user wireless channel, bridging the respective interest
of antenna and signal processing groups. ATBBF establishes a set of orthogonal beams in space, each of
which is weighted by an adaptive beamspace weight. The overall beam pattern is determined by the
superposition of beamspace weighted orthogonal beams. The ATBBF algorithm perturbs beamspace
weights at the base station to generate even and odd beamspace weights which are time multiplexed with
the pilot signal. The mobile feedbacks a single bit to indicate which of the two beamspace weights
delivered more power. This weight becomes the new beamspace weight. The beamspace weights and the
beam pattern continue to be updated, finally converging to the optimum. Simulations in single, double
and triple multipath wireless channels demonstrate the unique evolution of ATBBF's beam pattern in
relation to the convergence of its beamspace weights. The dependence of magnitude and convergence
time of a beamspace weight upon the multipath wireless channel is clarified to understand this evolution.
S. S. Irfan Hussain, M. Imran Shiekh. (2011) Beam Pattern Evolution of an Adaptive Transmit Beamspace Beamformer, Pakistan Journal of Engineering and Applied Sciences, Volume 8, Issue 1.
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