Transceiver design for reliable free space optical communications

Free space optical (FSO) communication offers the advantages of compact terminals and very high data rates without using scarce radio frequency spectrum. Unfortunately cloud and fog, together with scintillation caused by small temperature variations in the atmosphere, can result in significant attenuation and highly variable amplitude fluctuations that degrade link availability. This paper describes a 2 Mbit/s FSO modem and codec design, that includes a suitably large interleaver and strong channel coding scheme using a low density parity check (LDPC) code, plus synchronisation algorithms, to provide reliable communication over a 12 km optical channel.

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