Free-space optical (FSO) laser communication systems offer exceptionally
wide-bandwidth, secure connections between platforms that cannot other
wise be connected via physical means such as optical fiber or cable.
However, FSO links are subject to strong channel fading due to
atmospheric turbulence and beam pointing errors, limiting practical
performance and reliability. We have developed a fade-tolerant
architecture based on forward error correcting codes (FECs) combined with
delayed, redundant, sub-channels. This redundancy is made feasible though
dense wavelength division multiplexing (WDM) and/or high-order M-ary
modulation. Experiments and simulations show that error-free
communications is feasible even when faced with fades that are tens of
milliseconds long. We describe plans for practical implementation of a
complete system operating at 2.5 Gbps.