Optimization of survivable mesh long-reach hybrid WDM-TDM PONs

Long-reach hybrid wavelength-division multiplexing (WDM) and time-division multiplexing (TDM) passive optical networks (PONs) allow deploying access networks for remote service areas with thousands of customers. Typically, several long fiber cables are run between the central office (CO) of the service provider and each service area in order to feed the service area with data flows. In the service area, array waveguide gratings (AWGs) multiplex and demultiplex wavelengths; then, splitters split wavelengths in order to serve multiple optical network units. This paper proposes use of a mesh topology in service areas, i.e., AWGs can feed each other. This architecture has two main advantages. First, mesh linkages between AWGs make the network structure more robust with a high possibility of integrating survivable schemes. Second, fewer fibers are required between the CO and service areas, leading to a reduction of total length of fiber deployment, with a corresponding reduction of fiber installation and maintenance costs. We support this proposal by showing that i) the proposed architecture is feasible with some modification/combination of conventional PON devices, and ii) while using our optimal and heuristic algorithms for designing survivable long-reach hybrid WDM-TDM PONs, most of these PONs should use the mesh topology in order to minimize the total length of fiber deployment.