AN IMPROVED ANALYSIS FOR OPTICALLY PREAMPLIFIED PULSE-POSITION MODULATION RECEIVERS IN OPTICAL-FIBER SYSTEMS

Using a recently developed moment-generating function (MGF) we apply a Chernoff bound to the bit-error probability of an optically preamplif ied pulse-position modulation (PPM) receiver. Sensitivity results for PPM coding levels are presented for operation at the STM-I bit rate. I t is shown that this receiver configuration can outperform an equivale nt on-off-keyed nonreturn-to-zero (OOK NRZ) system by 7.1 dB. We furth er demonstrate the impressive potential of such an optically preamplif ied PPM receiver by going results that improve on the fundamental sens itivity limit of an optically preamplified OOK NRZ receiver and approa ch the sensitivity of coherent detection. A Gaussian approximation is also developed and we compare it with results obtained from the Cherno ff bound. (C) 1995 John Wiley & Sons, Inc.