Rateless Coding on Experimental Temporally Correlated FSO Channels

We present a demonstration of two error-correction coding schemes that can successfully operate on a free-space optical (FSO) communication channel subject to atmospheric turbulence. The codes (a puntured Low-density parity-check code and a Raptor code) operate by continuously adapting the information rate to accommodate the varying channel conditions. Because these coding schemes require the use of a feedback channel, we evaluate the bandwidth cost incurred. The evaluation of the codes is performed offline and uses experimental optical signals recorded from an FSO link. We analyze the temporal characteristics of the experimental channels and compare the performance of the codes for different bit rates to asses the effect of temporal correlation and imperfect channel state information.