Gw. Marsh et Jm. Khan, 50-MB S DIFFUSE INFRARED FREE-SPACE LINK USING ON-OFF KEYING WITH DECISION-FEEDBACK EQUALIZATION/, IEEE photonics technology letters, 6(10), 1994, pp. 1268-1270
We report an experimental 50-Mb/s free-space infrared link for indoor
wireless communication, which achieves low bit-error rates (BERs) in t
he presence of multipath distortion, shadowing, and ambient natural an
d artificial lighting. The eye-safe 806 nm transmitter, directed at th
e ceiling, emits an on-off-keyed signal having 475-mW average power. T
he receiver employs a 1-cm2 silicon p-i-n photodiode coupled to a high
-index hemispherical concentrator, which is covered by an optical band
-pass filter of 30-nm bandwidth. A decision-feedback equalizer mitigat
es the effect of multipath ISI. In the presence of bright skylight, th
e link achieves a range of 2.9 m at 10(-7) BER.