Performance limits of spectrally-efficient WDM direct-detection SSB Nyquist subcarrier modulation with signal-signal beat interference cancellation

We carried out a simulation-based study assessing the performance of WDM direct-detection dispersion pre-compensated single-sideband (SSB) Nyquist-pulse-shaped QAM subcarrier modulated (N-SCM) systems using a receiver-based signal-signal beat interference (SSBI) cancellation technique. The performance improvement with SSBI cancellation, which compensates for the nonlinear distortion caused by square-law detection, was quantified for 9 × 112 Gb/s 16-QAM and 9 × 224 Gb/s 64-QAM N-SCM signals with net optical information spectral densities (ISD) of 2.1 (b/s)/Hz and 4.1 (b/s)/Hz respectively. The simulations predict significant reductions in the required OSNR, and increases of up to 45% in transmission distance over uncompensated standard single-mode fibre (SSMF) using the SSBI compensation technique.