A-posteriori access strategies in all-optical slotted WDM rings

The paper compares a number of strategies devised to gain access in slotted multi-channel all-optical ring networks whose nodes have a distinct transmission queues for each channel and limited transmission/reception capabilities, i.e., one tunable transmitter and one fixed receiver. The considered access strategies can be subdivided into two groups, depending on the information used to select the next packet for transmission. "A-priori" strategies select the packet only according to the knowledge of the state of transmission queues. "A-posteriori" strategies rely on the knowledge of the state of both transmission queues and optical channels. A number of strategies belonging to the former group were recently proposed by the authors and offer an intrinsic hardware and algorithmic simplicity. Two novel strategies belonging to the latter group are proposed in this paper with the aim of assessing the trade-offs between complexity and overall system performance, including achievable throughput and queuing delay. Simulation results obtained under several traffic scenarios show that the increased complexity of a-posteriori strategies pays off in terms of performance.