Interference Cancellation for Time-Frequency Packed Super-Nyquist WDM Systems

We consider time and frequency-packed super-Nyquist wavelength-division-multiplexed (WDM) optical longhaul transmission targeting Terabit data rates. With fiber nonlinearities precluding the feasibility of employing very high modulation formats, super-Nyquist transmission can facilitate such high data rates at the price of deliberate introduction of inter-symbol and inter-carrier interference. To counter these effects, we investigate low-complexity linear, and high-performance iterative interference mitigation approaches. Moreover, WDM systems may also undergo additional distortions due to narrow optical filtering by cascades of wavelength-selective switches. In the presence of such aggressive filtering, our numerical simulations show that super-Nyquist systems can manifest substantial optical-signal-to-noise-ratio advantages over Nyquist WDM transmission to achieve the target data rate.