Regenerator placement algorithms for connection establishment in all-optical networks

In wavelength-routed all-optical networks, signals are transmitted on a dir ect optical path, or a lightpath, in a single-hop manner without opto-elect ronic/electro-optic (OE/EO) conversion at intermediate nodes. However, due to the physical constraints of optical elements such as ASE noise and cross talk. signals can be degraded on a long path. To establish a connection und er such impairments, the optical signal mag; need to be regenerated at inte rmediate nodes, dividing a lightpath into two or more fragments. However, s ince signal regeneration at intermediate nodes requires additional network resources, the selection of these nodes should be made carefully to minimis e blocking of other lightpaths. The problem of establishing a lightpath in a multihop manner under physical constraints is considered. The authors pro vide both minimal-cost and heuristic algorithms for locating signal regener ation nodes (SRNs). For a minimal-cost algorithm, the problem is formulated using dynamic programming (DP) such that blocking of other lightpaths due to the lack of transmitters:receivers (TXs/RXs) and wavelengths is minimise d throughout the network. The blocking performances of the algorithms are c ompared with several other algorithms in a ring network.