Performance impact of partial reconfigurability in lightwave networks

Rearrangeable multihop lightwave networks can be dynamically reconfigured to adapt the connectivity among network stations to prevailing traffic conditions. Most of the literature has analyzed the performance of such networks assuming no limitations on the range of tunability of the transmitters and/or receivers allocated to each network station. Therefore, all connection diagrams could be realized among network stations, within the constraints of the number of transmitters and receivers at each station. Since the number of wavelengths in use may be very large, a practical implementation would restrict the tunability range of each transmitter and receiver to some limited set of contiguous wavelengths, or waveband. However, there is a penalty associated with such restrictions in that all connection diagrams might not be achievable and the network performances could degrade. The author derives lower bounds on the performance degradation experienced by the network when there are tunability limitations. He then proposes and analyzes a waveband assignment and grouping scheme, illustrating that one can design networks with good performance even though there are tunability constraints on the transceivers. He also describes other architectures (multi-fiber physical topology, subcarrier division multiplexing) for which the model and analysis readily apply