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On the Capacity of WDM Passive Optical Networks

To lower costs, WDM PONs may share the usage of wavelengths, transmitters, and receivers among ONUs, instead of dedicating the transmission between OLT and each ONU with one individual wavelength and one individual pair of transmitter and receiver. The specific sharing strategy depends on the network architecture and the wavelength supports of transmitters and receivers. Different sharing strategies may yield different achievable data rates of ONUs. In this paper, we make three main contributions in investigating the impact of the sharing strategy on the capacity region of a WDM PON. First, we abstract the data transmission processes in WDM PONs into directed graphs, where arcs represent wavelengths, transmitters, and receivers, as well as relations between them. Second, we apply Ford and Fulkerson's Max-flow, Min-cut Theorem to derive the upper bound of the capacity region of a WDM PON, and prove that the upper bound is achievable. Third, in light of these analytical results, we discuss and compare capacities of some WDM PON architectures.