50-MB S DIFFUSE INFRARED FREE-SPACE LINK USING ON-OFF KEYING WITH DECISION-FEEDBACK EQUALIZATION/

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.