Reduced load approximation for WDM rings with wavelength continuity constraint

A reduced load approximation for WDM rings with a wavelength continuity constraint under Poissonian, homogeneous traffic with any spatial profile is presented. The model accounts for interactions among successive links in a linear network, correcting the overestimation of the blocking probability caused by the link independence assumption. Comparisons with simulation results show that the proposed reduced load approximation is a better substitute for the well-known reduced load approximation that uses the link independence assumption for blocking computation. It is shown that the proposed model provides accurate estimates of blocking probabilities in WDM rings with a wavelength continuity constraint. (C) 2006 Optical Society of America.51293794

A New Analytical Approach For The Estimation Of Blocking Probabilities In Linear All-optical Networks

The paper introduces a new analytical approach for estimating blocking probabilities in linear all-optical networks. The assumptions of the classical Lee approximation are discussed and their effects are evaluated. The paper proposes a better substitute for the independent link assumption. The new assumption takes all active paths, as well as all free links, as independent objects on the network topology. The new model is shown to generate estimates that fit exactly the blocking probabilities obtained through simulations on linear topologies using Poissonian, single-wavelength spatially homogeneous traffic. Finally, the independent wavelength assumption is also evaluated.524782482Lee, C.Y., Analysis of switching networks (1955) Bell Syst. Tech. J., 34, pp. 1287-1315. , NovBarry, R.A., Humblet, P.A., Models of blocking probability in all-optical networks with and without wavelength changers (1996) IEEE J. Select. Areas Comm., 14 (5), pp. 858-867. , JunSubramaniam, S., Azizog̃lu, M., Somani, A.K., All-optical networks with sparse wavelength conversion (1996) IEEE/ACM Trans. Networking, 4, pp. 544-557. , AugHui, J.Y., (1990) Switching and Traffic Theory for Integrated Broadband Networks, , Kluwer Academic PublishersZang, H., Jue, J.P., Mukherjee, B., A review of routing and wavelength assignment approaches for wavelength-routed optical WDM networks (2000) SPIE Optical Networks Magazine, 1 (1), pp. 47-60. , JanWaldman, H., Campelo, D.R., Camelo, R., Dynamic priority strategies for wavelength assignment in WDM rings (2000) Proc. IEEE GLOBECOM'00, pp. 1288-1292. , San Francisco, CA, NovGeary, N., Antonopoulos, A., Mitchell, J., Ultra long haul transmission and reconfigurable OADMs for national-scale optical networks (2003) Proc. ONDM'03, 1, pp. 113-126. , Budapest, Hungary, Fe

Resource allocation and scalability in dynamic wavelength-routed optical networks.

This thesis investigates the potential benefits of dynamic operation of wavelength-routed optical networks (WRONs) compared to the static approach. It is widely believed that dynamic operation of WRONs would overcome the inefficiencies of the static allocation in improving resource use. By rapidly allocating resources only when and where required, dynamic networks could potentially provide the same service that static networks but at decreased cost, very attractive to network operators. This hypothesis, however, has not been verified. It is therefore the focus of this thesis to investigate whether dynamic operation of WRONs can save significant number of wavelengths compared to the static approach whilst maintaining acceptable levels of delay and scalability. Firstly, the wavelength-routed optical-burst-switching (WR-OBS) network architecture is selected as the dynamic architecture to be studied, due to its feasibility of implementation and its improved network performance. Then, the wavelength requirements of dynamic WR-OBS are evaluated by means of novel analysis and simulation and compared to that of static networks for uniform and non-uniform traffic demand. It is shown that dynamic WR-OBS saves wavelengths with respect to the static approach only at low loads and especially for sparsely connected networks and that wavelength conversion is a key capability to significantly increase the benefits of dynamic operation. The mean delay introduced by dynamic operation of WR-OBS is then assessed. The results show that the extra delay is not significant as to violate end-to-end limits of time-sensitive applications. Finally, the limiting scalability of WR-OBS as a function of the lightpath allocation algorithm computational complexity is studied. The trade-off between the request processing time and blocking probability is investigated and a new low-blocking and scalable lightpath allocation algorithm which improves the mentioned trade-off is proposed. The presented algorithms and results can be used in the analysis and design of dynamic WRONs