Colorless, Directionless and Contentionless multi-degree ROADM architecture for mesh optical networks
DOI: 10.1109/COMSNETS.2010.5431987 Conference: Communication Systems and Networks (COMSNETS), 2010 Second International Conference on
A Colorless and Directionless (C&D) ROADM architecture has empowered today's networks with the much needed flexibility and scalability to handle the unpredictable high bandwidth demands, provide any-to-any connectivity and provision new services without disrupting the existing ones. In this paper, we realize the C&D ROADM architectures using PXC and WSS at a multi-degree node. We then evaluate both the architectures based on the various advantages offered by them. We also discuss some of the drawbacks of the two architectures. Subsequently, we propose a Colorless, Directionless and Contentionless (CD&C) architecture which combines the features offered by both the C&D architectures. Finally, we discuss practical implementation issues of the proposed architecture.
Available from: Ajmal Muhammad
- "In order to reduce the number of required ports, and consequently the cost and control complexity , multigranular OXC (MG-OXC) has been proposed in , which performs fiber, waveband, or wavelength switching. Similarly, colorless, directionless, and contentionless reconfigurable optical add–drop multiplexer (CDC-ROADM) architectures have been proposed in    . In CDC-ROADMs, ports are not associated with any specific wavelength or node degree and multiple ports can simultaneously add/drop different channels at the same wavelength. "
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ABSTRACT: Elastic optical networks are envisaged as promising solutions to fulfill the diverse bandwidth re-quirements for the emerging heterogeneous network applications. To support flexible allocation of spectrum re-sources the optical network nodes need to be agile. Among the different proposed solutions for elastic nodes, the one based on architecture of demand (AoD) exhibits consider-able flexibility against the other alternatives. The node modules in the case of AoD are not hard-wired, but can be connected/disconnected to any input/output port accord-ing to the requirements. Thus, each AoD node and the net-work (fabricated with AoD nodes) as a whole acts like an optical field-programmable gate array. This flexibility in-herent in AoD can be exploited for different purposes, such as for cost-efficient and energy-efficient design of the networks. This study looks into the cost-efficient network planning issue for synthetic networks implemented through AoD nodes. The problem is formalized as an inte-ger linear programming formulation for presenting the optimal solution. Furthermore, a scalable and effective heuristic algorithm is proposed for cost-efficient design, and its performance is compared with the optimal solution. The designed networks with AoD nodes are further inves-tigated for a dynamic scenario, and their blocking probabil-ity due to limited switching resources in the nodes is examined. To alleviate the blocking performance for the dy-namic case, an efficient synthesis strategy along with a scheme for optimal placement of switching resources within the network nodes is presented. Extensive results show that 1) even at high loads, the network with AoD nodes achieves saving of switching modules up to 40% com-pared to the one with static reconfigurable optical add– drop multiplexers (ROADMs) through a proper network design, 2) by diminishing the spectrum selective switches the overall power consumption of the network decreases by more than 25% for high loads, and 3) for the dynamic sce-nario the blocking owing to the node modules constraint is alleviated significantly by slightly augmenting the switch-ing devices and optimally deploying them within the network nodes.
Available from: Christine Tremblay
- "First, a filterless solution proposes the minimization of wavelength selective filters and active switches. (Note that passive optical splitters and combiners implement the passive local add–drop function in a colorless fashion, which helps to reduce operational constraints related to the colorless, directionless, and gridless concepts .) Second, filterless networks exploit recent breakthroughs in digital signal processing and electronically compensated dispersion. "
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ABSTRACT: In this paper, we study the performance of dynamic routing and wavelength assignment (RWA) in filterless optical networks. These types of broadcast and select networks benefit from breakthroughs in advanced transmission technologies for replacing optical filters and active photonic switching devices, such as wavelength selective switches, with passive optical interconnections between nodes, creating passive optical light trees. We introduce an RWA scheme for establishing passive optical lightpaths in a filterless context and managing unfiltered channels at intermediate egress nodes, which, by propagating downstream of the terminating nodes, participate in wavelength usage and increase the risk of wavelength exhaustion. Simulation results are presented for six network topologies, along with the performance evaluation of active photonic and filterless optical network solutions with static and dynamic RWA schemes. We show that the performance of the proposed scheme depends on the average degree of node connectivity.
Available from: Lida Sadeghioon
- "As a result 60 % of nodal transponders are eliminated in transparent network comparing to legacy OEO node architecture . Colorless directionless contention-less optical adddrop multiplexers, which were proposed in  multiple ports can simultaneously add/drop different channels at the same wavelength. By using ROADMs, many optical to electrical (OE) and electrical to optical (EO) conversions are avoided at intermediate nodes but it induces a non optimum channel use. "
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ABSTRACT: We present a new method to design a regional network based on optical hybrid packet and circuit switching. Our approach aims at providing packet-level grooming only where it is profitable. The method relies on splitting the original traffic matrix in two parts, which will be transported either through optical packets or through circuits, according to a maximum wavelength capacity threshold. The network dimensioning can be then performed for circuit and packet traffic matrices separately. As the circuit WDM network design problem is well documented, we put the emphasis on the optical packet network dimensioning. This later is performed in the context of Packet OADM (POADM) technology, involving fast tuneable emitters and receivers dedicated to specific wavelengths. First, candidate sets of rings are identified. Then, the resources needed for each ring of a given set are evaluated by taking into account both. receiver and wavelength costs. The “wavelength cost” depends on the considered ring, as it is proportional to its circumference. A linear programing formulation, previously established for unidirectional rings, is adapted to bi-directional ones with shortest distance routing and 1+1 protection. The proposed method is applied to a 7 nodes network by considering different scenarios in terms of content-delivery node positions, wavelength capacity threshold or network geographical extension. Even if most of the traffic is carried by circuits, POADM technology is widely used as a grooming technique across the network. The benefits of using POADM technology are achieved without necessitating O/E/O conversions at packet ring interconnections and alleviating inter-ring synchronization issues, resulting in a fully transparent network.
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