Interleaved concatenated coding for the turbulent atmospheric direct detection optical communication channel

The performance of two concatenated coding systems using a K=3, R=1/2 convolutional inner code and a Reed-Solomon (RS) (15, 9) or (15, 7) outer code was measured over a 5.76-km-long atmospheric direct detection optical communication channel. Inner code interleaving of 100 mu s combined with outer code interleaving of 240 bits (60 RS symbols) was found to be sufficient to obtain a decoded BER of less than 10/sup -6/ under conditions of moderate channel turbulence and an average of 6-10 detected photons per channel bit.<
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