We discuss two modifications to the design of wireless infrared links that
can yield significant performance improvements, albeit at the price of incr
eased complexity. In line-of-sight and non-line-of-sight links, replacement
of a single-element receiver by one employing an imaging light concentrato
r and a segmented photodetector can reduce received ambient light noise and
multipath distortion. For a fixed receiver entrance area, such an imaging
receiver can reduce transmit power requirements by as much as about 14 dB,
depending on the link design and the number of photodetector segments. Imag
ing receivers also reduce co-channel interference, and may therefore enable
infrared wireless networks to employ space- division multiplexing, wherein
several transmitters located in close proximity can transmit simultaneousl
y at the same wavelength. In nondirected non-line-of-sight links, replaceme
nt of the diffuse transmitter by one that projects multiple narrow beams ca
n reduce the path loss, further reducing the transmit power requirement by
several decibels. We describe the design of an experimental 100 Mb/s infrar
ed wireless link employing a multibeam transmitter and a 37-pixel imaging r
eceiver.