Time-driven switching

Abstract: This article introduces fractional lambda (λ) switching (FλS) and studies its blocking issues. FλS uses a global common time reference (CTR) for implementing pipeline forwarding (PF) inside the network. A global CTR is conveniently realized with the UTC (coordinated universal time) standard. Resource reservation over an FλS network requires a schedule. As in other scheduling cases, a call may not be accepted, even though there is enough capacity, because the schedule is not available—the call is then considered blocked. This work studies the probability of call blocking as a function of link utilization. The results show that (especially if multiple-wavelength division multiplexing channels are deployed on optical links between fractional λ switches) high-link utilization can be achieved with negligible call blocking, even when the switching fabric is a Banyan network.

Abstract: A new approach is introduced in this paper to make possible a flexible utilization of WDM networks using current technology. It is shown that the bandwidth made available end-to-end by a single wavelength can be simply broken up into smaller pieces, or fraction of lambda, by relying on a worldwide common time reference system, such as GPS, previously deployed for different applications. The common time reference system is used to synchronize switches and to facilitate pipeline forwarding of data units. Pipeline forwarding is a known optimal method widely used in manufacturing and computing. It is shown how this new approach, called Time Driven Switching, behaves in terms of call blocking when the basic parameters of the scheme are varied.

Abstract: This study is concerned with the problem of composite anti-disturbance control for switched linear systems with multiple disturbances. The authors' aim is to construct a disturbance observer to estimate the disturbance generated by an exogenous system, then design a composite controller based on the disturbance observer and a mixed state-dependent and time-driven switching law, such that the closed-loop system is internally stable, and different types of disturbances are attenuated and rejected. First, a mixed switching law is designed, which guarantees a dwell time even when all subsystems are unstable. Then, a sufficient condition ensuring the solvability of the composite anti-disturbance control problem is presented via multiple Lyapunov functions. Finally, the effectiveness of the proposed control design scheme is illustrated by its application to an aero-engine, which cannot be handled by the existing approaches.

Abstract: Fractional Lambda (λ) Switching (FλSTM) adds the necessary efficiency to Wavelength Division Multiplexing (WDM) while preserving the simplicity of whole λ switching. Due to its provisioning capability, from a fraction of STS-1 to a full optical channel capacity, FλSTM will extend the reach of optical networking all the way to the network edges in the metro and enterprise. Finally, FλSTM uniquely enables the implementation of dynamic all-optical switches since its operation does not require (1) optical processing (e.g., packet header processing) and (2) optical buffering.