Load balancing - node transfer trade-off in reconfigurable WDM networks

When the traffic demand changes in single-hop WDM broadcast and select networks, the load can become unbalanced. This situation leads to poor resource utilisation and the wavelength assignment (WLA) requires reconfiguring to maintain a balanced load. The problem of reconfiguring the wavelength assignment in single-hop WDM networks is considered here. Topologies used in the study are passive star and bus networks, and all nodes in the network are assumed equipped with fast tunable transmitters (FTTs) and slowly tunable receivers (STRs). When reconfiguring the WLA according to the new traffic demand, it is important to reduce the number of receivers that need to be retuned to provide low disruption to the network traffic and thus correspondingly reduce the periods when the network operation is suspended during the retuning. The trade-off here is thus between the number of node transfers and the degree of network load balance. A new WLA reconfiguration algorithm is introduced, the one direction transfer (IDT) algorithm, which provides a low number of retunings and an excellent load balance. The IDT algorithm transfers a group of nodes from the highest loaded channels to the lowest loaded channels. A comparison between the proposed algorithm and previous algorithms found in the literature is carried out to demonstrate the efficiency of the proposed algorithm.