Performance impact of partial reconfiguration on multihop lightwave networks

Rearrangeable multihop lightwave networks can be dynamically reconfigured to adapt the connectivity among network stations to prevailing traffic conditions. With no limitations on the tunability range of the transmitters and/or receivers allocated to each network station, all connection diagrams can 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, the tunability range of transmitters/receivers will be restricted, in practice, to some limited set of contiguous wavelengths, or waveband. As a result, all connection diagrams might not be achievable and the network may loose some of its ability to adapt to traffic changes through reconfiguration. We derive bounds on the performance degradation experienced by the network as a function of the tunability restrictions. We then propose and analyze a waveband decomposition, illustrating how networks with good performance can be designed with tunability constraints on the transceivers. We also describe other architectures (subcarrier division multiplexing, multi-fiber physical topology) to which our model and analysis readily apply.