Performance assessment of short-reach multi-level pulse-amplitude modulation transmission exploiting least-mean-square equalisation.

The authors study the performance of pulse-amplitude modulation, with 2, 4 and 8 levels per symbol, for short reach applications with propagation over up to 2 km of standard single mode fibre. They consider the three modulation formats operated both at the same bit-rate of 25 Gbps and at same symbol rate of 25 Gbaud, supposing 3.125% forward error-correction overhead and bit error rate threshold of 10-4. They analyse transmitters (Tx) and receivers (Rx) based on digital signal processing, including a training-driven finite impulse response (FIR) filter equaliser set through the least-mean-square algorithm. They analyse the sensitivity impairments induced by a limited Tx/Rx electrical bandwidth and evaluate the minimum number of taps - and consequent latency - needed by the FIR equaliser to obtain sensitivity benefits. [ABSTRACT FROM AUTHOR]