Switching WDM Research Articles

An Approach to Resolving Contention Problem in an Optical Burst Switching WDM Network

We propose to use a new wavelength allocation (WA) scheme with deflection routing, whilst investigating its influence to the optical burst switching (OBS) node performance. To evaluate the burst blocking probability we have developed the analytical and simulation models of an OBS node performing WA scheme in conjunction with the deflection routing. The results obtained from the analytical and simulation models indicate that the WA scheme yields to decrease the deflected burst blocking probability and reduces the cost of OBS node in WDM optical network. Ill. 6, bibl. 7 (in English; summaries in English, Russian and Lithuanian).

A Comparison of Elastic and Mixed Line Rate Optical Slot Switching WDM Metro Rings

We propose optimal resource allocation techniques for two kinds of optical slot switching metro rings: 1) fixed mixed line rate (fMLR), where the rate of each transponder (TRX) is fixed and set at network planning time; and 2) elastic TRX, where the rate may adjust dynamically on a per-slot basis during network operation. We then numerically compare the cost (CAPEX or energy) of fMLR and elastic networks, and investigate the suitability of each of the two considered network technologies for several ring topologies, TRX cost models, and traffic distributions and loads.

Dynamic routing and wavelength assignment in multi-granularity WDM networks

For the purpose of reducing the complexity and cost of optical large-scale cross-connect, wavelengths are grouped into wavebands or fiber to be switched as a single entity, which is called multi- granularity switching. However, it introduces more complexity into the routing and wavelength assignment problem. In this paper, we propose a novel graph model for describing the states of the multi-granularity switching WDM networks. Based on the model, the dynamic routing and wavelength assignment problems for multi-granularity traffic can be solved jointly, and different on-line wavelength grooming policies can be achieved simultaneously. By simulation, we compared the performance of our algorithms under different policy and different percent of fibers for fiber switching. The result proved that our algorithms yield better performance than those deal with the routing and wavelength assignment separately.

A New QoS-based Scheduling Algorithm in Optical Burst Switching WDM Networks

This paper proposes a new scheduling algorithm in core routers to support QoS (Quality of Service) in optical burst switching networks. In the proposed WQS (Waiting-Queuing-Scheduling) algorithm, all BHPs (Burst Header Packets) during the waiting time are deliberately and properly delayed, and added to input queues with a policy. Using currently well-known scheduling algorithms as its sub-algorithm, the proposed scheme is rather simple and feasible, and can yield a good performance. The simulation results show that the burst loss probabilities of higher classes can be decreased greatly, while not introducing much end-to-end delay. In addition, with proper waiting time, the average loss probability can also be decreased.