Ahmed Mokhtar

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In this paper we consider routing and wavelength assignment in wavelength-routed all-optical networks with circuitswitching. The conventional approaches to address this issue consider the two aspects of the problem disjointly by first finding a route from a predetermined set of candidate paths and then searching for an appropriate wavelength assignment. We(More)
We consider the effects of tuning d e l a y in optical broadcast networks. We show that for offl ine scheduling these effects are small even i f the tuning time is as large as the packet duration. In particular, we consider scheduling of random traffic with tunable transmitters and fixed-tuned receivers. We provide a lower bound to the completaon time of(More)
AbstrartA stochastic framework for modeling the performance of the RED algorithm is presented. A two-dimensional second-order discrete-time Markov chain is introduced to model the feedback effect of packet dropping on the incoming traffic. The mean system occupancy, packet drop probability, and system throughput are computed from the analytical model. The(More)
In this paper, we analyze the performance of a packet-switched broadcast-and-select all-optical network with N nodes and W wavelengths. We model the network as an N N space-division time-slotted packet switch. Each input port has a buuer to store incoming packets until they are switched. In each time slot, a set of W ports is selected to transmit their(More)
In this letter, we analyze the throughput of the downlink segment of a low Earth orbit (LEO) global broadband satellite network. The downlink design uses a set of hopping spot beams, each of which can he pointed independently to any fixed earth cell within the satellite footprint on a per-packet basis. We present upper and lower bounds on the downlink(More)
This letter considers a problem that arises in the context of statistical, state-dependent resource allocation in communication networks. Specifically, the problem concerns a single-server discrete-time queue with state-dependent probabilistic server interruptions. The system is analyzed for two forms of probabilistic behavior: exponential and hyperbolic(More)
A programmable spread spectrum clock generator (PSSCG) using fractional-N phase-locked loop (PLL) is presented. Spreading is achieved by modulating the feedback divider using a triangular wave through a ΣΔ modulator. In order to allow wide spreading ratios a new technique is adopted to keep the triangular wave within the input range of the(More)
In this paper, we consider routing and wavelength assignment in wavelength-routed all-optical networks with circuit-switching. The conventional approaches to address this issue consider the two aspects of the problem sequentially by rst nding a route from a predetermined set of candidate paths and then searching for an appropriate wavelength assignment. We(More)