Abstract
In this paper, we contrive a model that underpins the offline Physical Layer Impairment-Routing and Wavelength Assignment (PLI-RWA) issue in translucent networks. We introduce an innovative PLI-Signal Quality Aware RWA (PLI-SQARWA) algorithm that (a) guarantees zero blocking due to signal degradation and wavelength contention and (b) aims at minimizing the total required number of network components i.e. regenerators and all-optical wavelength converters (AOWCs). Further, in view of reducing the time delay due to optical-electrical-optical (OEO) conversions, we propose a novel electro-optical hybrid translucent node architecture. We show that PLI-SQARWA outperforms a recent heuristic for RWA and regenerator placement (RP) in terms of capital expenditure (CapEx) and time delay; while demonstrating superior blocking performance at all traffic loads. In addition, at high traffic loads, PLI-SQARWA also starts to provision savings on operational expenditure (OpEx). We proceed to the performance comparison of network equipped with the proposed hybrid node and existing translucent and transparent node architectures. The results clearly show that use of the hybrid node incurs less time delay at a similar blocking performance shown by nodes which use OEO conversion for both, regeneration and/or wavelength conversion. The results presented also highlight the significance of equipping the PLI-RWA routing phase with signal quality awareness in order to reduce the network component count and the use of AOWCs to minimize time delay due to OEO conversions.
Highlights
Routing and wavelength assignment (RWA) is vital for efficient wavelength division multiplexed (WDM) network design [1]
The results clearly show that use of the hybrid node incurs less time delay at a similar blocking performance shown by nodes which use OEO conversion for both, regeneration and/or wavelength conversion
The results shown in this paper correspond to those parameters which provided the best performances and their values are reproduced so as to allow the results to be repeatable: 1) for computation of k-alternate shortest paths (k-shortest path (SP)) associated to each demand, the value of k is set to 5; 2) COR2P cost function is simplified by setting the ratio CC/CO to 1, where CO is the unitary OpEx cost corresponding to the cost for managing a single active regenerator at a node and CC is the unitary CapEx cost corresponding to carrier’s investment for installing a regeneration pool at a node; and 3) simulations cover 6 traffic loads that range from 100 to 600 connection demands and for each load, 10 static traffic matrices are generated stochastically according to uniform distribution
Summary
Routing and wavelength assignment (RWA) is vital for efficient wavelength division multiplexed (WDM) network design [1]. It may occur that any other route(s), apart from SP, exhibits better signal quality, requiring fewer intermediate regenerators and in turn lowering the overall network cost This can be justified by considering the simple topology shown in Figure 1 wherein; a request originates at the source node (N1) demanding connection till the destination node (N6). The contributions of this paper are twofold: An innovative PLI-Signal Quality Aware RWA (PLISQARWA) algorithm is introduced that 1) guarantees zero blocking due to signal degradation and wavelength contention, and 2) minimizes the total required network components by a) considering signal quality to route connections over paths requiring fewest numbers of regenerators, and b) maximally using placed regenerators for wavelength conversion (WC) before resorting to AOWCs, which in recent years have been demonstrated to be practical [9].
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