Optical Next-Generation Access Networks Featuring Combined WDM and TDM

Current TDM-PONs are unlikely to provide sufficient bandwidth for emerging high-quality video and multimedia applications. Consequently, topologies combining and overlaying TDM-PONs with WDM are currently being investigated. In this work, we present a seamless upgrade path from TDM-PONs to WDM-PONs; provision being made on an on-demand basis that is transparent to existing deployments. In these next- generation networks, wavelength routers are added to existing TDM-PON infrastructures together with an advanced network head-end. Bandwidth on demand can then be efficiently assigned while centralising all the network management. Complexity is therefore reduced whilst offering smooth metro-access convergence. We have performed comprehensive network simulations and optical transmission experiments, which demonstrate the feasibility of the proposed designs, topologies and protocols.