In-Field Demonstration of OFDM-Over-FSO

This letter reports the first in-field experiment of orthogonal frequency-division multiplexing (OFDM) over free-space optical channels at a rate of 300 Mb/s over a range of 1.87 km. Using customized commercial terminals, 20 OFDM channels with 2000 subcarriers each are transmitted with a 60-mW optical power in both clear and light-rain conditions. The received signals are digitized at 2 GSa/s and investigated on the symbol level. The experimental bit-error rates per channel and constellation diagrams are reported. Uncoded transmission has an average symbol-error rate on the order of 10 and 10 in clear conditions.