50-Mb/s diffuse infrared free-space link using on-off keying with decision-feedback equalization

Abstract

We report an experimental 50-Mb/s free-space infrared link for indoor wireless communication, which achieves low bit-error rates (BERs) in the presence of multipath distortion, shadowing, and ambient natural and artificial lighting. The eye-safe 806 nm transmitter, directed at the ceiling, emits an on-off-keyed signal having 475-mW average power. The receiver employs a 1-cm/sup 2/ Si p-i-n photodiode coupled to a high-index hemispherical concentrator, which is covered by an optical bandpass filter of 30-nm bandwidth. A decision-feedback equalizer mitigates the effect of multipath ISI. In the presence of bright skylight, the link achieves a range of 2.9 m at 10/sup -7/ BER.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>