Greedy channel selection procedure for the routing, wavelength assignment and spectrum allocation in the flexible optical WDM networks

1. A method implemented by a computer in a communications system including an optical flexible wavelength division multiplexing FWDM network, comprising the steps of:

i) finding an optimal set of line rates for a requested data rate of each connection in said FWDM using a channel selection for a total spectrum requirement for said set of line rates that is minimal;

ii) determining available channels with sufficient spectrum for each said connection in a given set of said each connection in a specific order;

iii) ascertaining K candidate channels on first available K wavelengths for each said connection, all channels having distinct wavelengths with some channels co-existing on a same route connecting end users of said connection, K being number of channels to be considered for each said connection; and

iv) selecting, out of said K candidate channels, a channel routed through a minimum number of physical optical paths, said K channels being found on first available said K wavelengths for confining selection of a channel for a given said connection at lower wavelengths thereby reducing spectrum required for said connection;

wherein the steps i)-iv) are carried out by a computer.

2. A method implemented by a computer in an optical flexible wavelength division multiplexing FWDM network, said method comprising:

i) finding a connection route in an optical FWDM network on which a channel with sufficient spectrum is available at lowest wavelength among all available channels;

ii) finding K channels at first available K lower wavelengths out of available channels for minimizing total required spectrum; and

iii) selecting a channel which is routed through minimum number of optical fiber paths out of said K available channels at one of said lower wavelengths;

wherein the steps i)-iii) are carried out by a computer.