FREQUENCIES in the 20–60-GHz range are being considered
for their wider allocated bandwidths and compactsized
devices [1], [2]. However, path loss and absorption due to
typical building materials are higher at these frequencies than at
cellular and PCS frequencies [1]. To compensate for this loss
and reduce multi path spread, multi beam antennas have been
considered [3], [4].
Driessen [5] showed that, with proper placement and pointing
of a 15 beamwidth horn antenna at one end of the link and with
a 45 or 70 beamwidth antenna at the other end of the link, 622
Mb/s BPSK and 1.244 Gb/s QPSK links without equalization
could be established at 19 GHz with error-free performance for
many indoor locations.
Gans et al. [6] concluded from a link budget analysis based
on a ray-tracing model that beamforming arrays with at least
50 elements at both ends of the link are required to achieve the
long range and high bit rate of Driessen’s [5]. They also considered
the required number of taps in a decision feedback equalizer
(DFE) versus the beamwidth, assuming an omnidirectional
antenna at the user transmitter and a continuously steerable directional
antenna at the base station (BS) receiver [6].
In this paper, we consider the same general architecture
as the second Gans model described above, but for a shorter
range (50 ft) and a lower bit rate of 100 Mb/s. We assume a
certain configuration of four linear beamformers (only discrete
beam-pointing choices) and a statistical (azimuth-only) propagation
model that emphasizes clustering of paths in angle and