Reducing Packet Delay in Single-Hop WDM Networks Using Fixed Transceiver Array and Adaptive Channel Allocation

This paper studies how to reduce packet delay in single-hop wavelength-division-multiplexed (WDM) networks with reservation-based scheduling algorithms. A number of approaches have been proposed in previous researches to reduce different components of the packet delay. This paper proposes two approaches to reduce the packet delay. The first approach is to replace the tunable transceivers in all of the nodes with fixed transceiver arrays such that no tuning latency is required, and each node is capable of transmitting and receiving multiple signals on multiple channels at the same time. The latter property enables the network to have better tolerance to traffics with nonuniform arrivals and nonuniform distribution of destinations that are commonly seen in network traffics. With a fixed transceiver array in each of the nodes, each channel becomes an independent broadcast channel such that broadcast and multicast communications can be efficiently supported. With fixed total number of channels in a transceiver-array-based single-hop WDM network, there is a tradeoff between the number of channels used for transmitting reservation (or control) information and the number of channels used for transmitting data packets. A network with fixed numbers of control and data channels is not able to cope with different traffic patterns. The optimal combination of the numbers of control and data channels depends on the traffic patterns. Therefore, our second approach is to develop an adaptive channel allocation algorithm to dynamically adjust the numbers of control and data channels according to the traffic patterns. The proposed adaptive channel allocation algorithm enables a transceiver-array-based single-hop WDM network to dynamically choose the best combination of the numbers of control and data channels for wide ranges of traffic patterns including nonuniform arrivals, nonuniform destination distributions, broadcast/multicast communications, and different system loads. The advantages of the proposed approaches are demonstrated in the simulation results