Internal switches in all-photonic networks do not perform data conversion into the electronic domain, thereby eliminating a potential capacity bottleneck, but the inability to perform efficient optical buffering introduces network scheduling challenges. In this paper we focus on the problem of scheduling fixed-length frames in allphotonic star-topology networks with the goal of minimizing rejected demand. We formulate the task as an optimization problem and characterize its complexity. We describe the Minimum Rejection Algorithm (MRA), which minimizes total rejection, and demonstrate that the Fair Matching Algorithm (FMA) minimizes the maximum percentage rejection of any connection. We analyze through OPNET simulation the rejection and delay performance.
This paper introduces afeedback control system based on Smith's principle for bandwidth reservation and scheduling of all-photonic networks with large propagation delay. The approach is also applicable to any singlehop network with significant signalling delay (such as satellite-TDMA systems). Scheduling in wide-area networks must be based on predictions oftraffic demand and the resultant errors can lead to instability and unfairness. Thefeedback control system we propose reduces the effect ofprediction errors, increases the speed ofthe response to the sudden changes in traffic arrival rates, and improves fairness through equalization ofqueue-lengths.
This paper describes a framework for fixed-length frame scheduling in all-photonic networks with large propagation delays. We introduce the Fair Matching Algorithm (FMA), a novel scheduling approach that results in weighted maxmin fair allocation of extra demands, achieves zero rejection for admissible demands, and minimizes the maximum percentage rejection of any connection. We also propose the Minimum Rejection Algorithm (MRA), which minimizes total rejection but treats non-critical connections in a fair manner. Finally, we introduce a feedback control system based on Smith's principle that reduces the effect of prediction errors and increases the speed of the response to the sudden changes in traffic arrival rates. Simulations performed using OPNET Modeler explore the performance of the scheduling and control algorithms we propose.
We study the problem of frequency and power allocation and scheduling at a time-slotted cognitive ad-hoc wireless network, where cognitive nodes share a number of frequency bands and frequency reuse is allowed. In such a network the throughput maximization problem generally results in a mixed zero-one nonlinear non-convex problem. Interestingly, in the low-SINR regime, the power allocation policy that maximizes the total throughput follows an "on/off" strategy with maximum power usage in the "on" state. In this paper we show that the on/off strategy in the low-SINR regime is also optimal with respect to throughput when scheduling users over time and frequency subject to minimum SINR requirements. We show that these additional constraints will not change the optimum strategy, but may affect the set of "on" or "off" transmitters. Also we present an approach that transforms the mixed zero-one nonlinear problem to an equivalent mixed zero-one linear problem at the expense of extra variables.
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