Comparison of coding strategies for a combined multi-Gbps fiber and twisted-pair link

Abstract

In this contribution we consider a communication system consisting of a cascade of a passive optical network (PON) link with on/off keying, and a short twisted pair (TP) link with discrete multitone modulation (DMT). Three coding configurations are investigated. In the first configuration (C1), the PON link and the TP link are protected by a Reed-Solomon (RS) code and trellis-coded modulation (TCM), respectively. In the second configuration (C2), the PON link is the same as with C1, but the TP link is now protected by the concatenation of an outer RS code and inner TCM. We compare these conventional coding configurations C1 and C2 with an alternative configuration (C3), in which an outer RS code protects the cascade of the uncoded PON and the TCM-encoded TP. Whereas the configuration C3 has the same complexity as the configuration C1, we show that the former is able to achieve approximately the same information bitrate as the (more complex) configuration C2, at the expense of a slightly (about 1 dB) higher optical power. Our numerical results for a typical setting indicate that the configurations C2 and C3 can provide information bitrates beyond 10 Gbps, which are about 20–25% larger than for configuration C1.