Reed-Solomon coded homodyne digital pulse position modulation

A performance and optimisation analysis for both uncoded homodyne digital PPM and digital PPM employing Reed-Solomon error-correction codes is presented. System performance for a range of fibre bandwidths and PPM symbol sizes is analysed, and it is shown how the predetection filter may be configured in order to minimise the three error sources and achieve maximum transmission efficiency (nats/photon). Results are presented at a bit rate of 565 Mbit/s and a wavelength of 1.5 mu m. It is shown that there are optimum PPM symbol sizes, fibre bandwidths and Reed-Solomon code rates at which to operate. The conclusion is that uncoded digital PPM offers an improvement of 5 dB over homodyne PSK PCM, and that the Reed-Solomon error-correction coded system offers a 4 dB improvement over uncoded PPM, when operating at the optimum 3/4 code rate.<>