We experimentally verify that pilot-based nonlinearity compensation is effective for mitigating XPM in CO-OFDM systems, if SPM is compensated first. A 6-dB increase in the nonlinear limit was produced by pilot-based XPM compensation after a single-step SPM compensator in a 400-km link with periodic dispersion compensation. In addition, we use numerical simulations to show that the required bandwidth of the guard-band around the pilot is almost independent of the bandwidth of the data-carrying sidebands. The optimal ratio of pilot to signal power also decreases for higher bandwidth OFDM signals. Therefore, the overhead associated with transmitting the pilot decreases as the bandwidth of the signal increases.
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