Joint Pre-emphasis and Partial-response Coding for Spectrum Narrowing Caused by Repeated Optical-node Traversal in Ultra-dense WDM Networks

We propose a novel pre-filtering scheme that combines pre-emphasis and partial-response coding to mitigate the spectrum narrowing caused by repeated optical-node traversal. Simulations show that our optimum pre-filtering scheme extends the maximum node-hop count and transmission distance by up to 13 and 1040 km, respectively.