Summary form only given. The M-ary PPM direct-detection optical communication channel in the presence of dark current can be represented as an M-ary symmetric erasure channel (MSEC). A binary finite-state channel model for the MSEC is developed that provides an interesting method of viewing the correlation between binary errors and erasures on the MSEC. Under the assumption of full state information about the finite-state model, the capacity and cutoff rate are calculated. These values exceed the standard capacity and cutoff rate of MSEC, indicating that interleaved binary coding methods utilizing the finite-state model have a potential superiority over standard M-ary coding schemes for the degraded direct-detection optical PPM channel. Based on the finite-state model, the authors also points out an interesting and practical coding implementation when perfect state knowledge is unavailable. This implementation utilizes a bank of correlated binary decoders with a provision for transferring information from one decoder to another. This allows the bank of correlated binary decoders to provide superior performance over the same bank of decoders working independently.
|Title of host publication||Unknown Host Publication Title|
|Place of Publication||New York, NY, USA|
|State||Published - Dec 1 1986|
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