Journal ArticleDOI
Elastic Bandwidth Allocation in Flexible OFDM-Based Optical Networks
TLDR
This work introduces the Routing, Modulation Level and Spectrum Allocation (RMLSA) problem, as opposed to the typical Routing and Wavelength Assignment (RWA) problem of traditional WDM networks, proves that it is also NP-complete and presents various algorithms to solve it.Abstract:
Orthogonal Frequency Division Multiplexing (OFDM) has recently been proposed as a modulation technique for optical networks, because of its good spectral efficiency, flexibility, and tolerance to impairments. We consider the planning problem of an OFDM optical network, where we are given a traffic matrix that includes the requested transmission rates of the connections to be served. Connections are provisioned for their requested rate by elastically allocating spectrum using a variable number of OFDM subcarriers and choosing an appropriate modulation level, taking into account the transmission distance. We introduce the Routing, Modulation Level and Spectrum Allocation (RMLSA) problem, as opposed to the typical Routing and Wavelength Assignment (RWA) problem of traditional WDM networks, prove that is also NP-complete and present various algorithms to solve it. We start by presenting an optimal ILP RMLSA algorithm that minimizes the spectrum used to serve the traffic matrix, and also present a decomposition method that breaks RMLSA into its two substituent subproblems, namely 1) routing and modulation level and 2) spectrum allocation (RML+SA), and solves them sequentially. We also propose a heuristic algorithm that serves connections one-by-one and use it to solve the planning problem by sequentially serving all the connections in the traffic matrix. In the sequential algorithm, we investigate two policies for defining the order in which connections are considered. We also use a simulated annealing meta-heuristic to obtain even better orderings. We examine the performance of the proposed algorithms through simulation experiments and evaluate the spectrum utilization benefits that can be obtained by utilizing OFDM elastic bandwidth allocation, when compared to a traditional WDM network.read more
Citations
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Journal ArticleDOI
Least loaded and route fragmentation aware RSA strategies for elastic optical networks
TL;DR: It has been conclusively established that the proposed routing and spectrum assignment strategies (LLRSA and RFARSA) outperform the existing strategies in terms of all the metrics.
Proceedings ArticleDOI
Shared path protection for distance adaptive elastic Optical Networks under dynamic traffic
Aras Tarhan,Cicek Cavdar +1 more
TL;DR: A novel RSA (Routing and Spectrum Allocation) algorithm applying different strategies for primary and backup resources called Primary First-Fit Modified Backup Last-Fit (PF-MBL) aiming to reduce the fragmentation and to increase the shareability is developed and overall bandwidth blocking probability is significantly reduced in the network.
Proceedings ArticleDOI
Fragmentation aware routing and spectrum assignment algorithm
TL;DR: Results indicate that the joint use of the new algorithm with proposed cost functions can produce bandwidth blocking ratio four orders of magnitude lower than existing RSA algorithms.
Proceedings ArticleDOI
Simulated Annealing algorithm for optimization of elastic optical networks with unicast and anycast traffic
Michal Aibin,Krzysztof Walkowiak +1 more
TL;DR: A novel heuristic algorithm is proposed that combines a Simulated Annealing approach and a simple greedy algorithm to solve the RSA problem and can improve the solution provided by a greedy algorithm by more than 10% and on average is about 4% worse in comparison to the optimal results.
Journal ArticleDOI
High Granularity Multiband OFDM Virtual Carrier-Assisted Direct-Detection Metro Networks
Abstract: A direct-detection metropolitan (metro) network employing multiband orthogonal frequency division multiplexing (MB-OFDM) signals (MORFEUS network) is proposed. The MORFEUS network employs virtual carriers to assist the detection of each OFDM band. It represents a cost-effective network enabling high granularity and flexibility, while requiring a reduced receiver bandwidth. The MB-OFDM signal structure and their main constraints are presented. Each MB-OFDM metro node is described and discussed, with particular attention dedicated to the blocks required to insert and extract a given OFDM band of the MB-OFDM signal. Conceptual solutions for the MORFEUS insertion and extraction blocks are also proposed and discussed. The performance of a 42.8-Gb/s MORFEUS network is evaluated through numerical simulation, and the network operation design is optimized. The impact of the optical filtering effect due to band add/drop operations is assessed as well. These studies are accomplished for systems employing band selectors (BS) with different selectivity to assess the performance tolerance to interband crosstalk and in-band amplitude distortion. The studies are performed for three MORFEUS networks, with granularity of 2-, 3-, and 4-bands. A required optical signal-to-noise ratio (OSNR) of 24 dB is demonstrated in a 240-km-long MORFEUS network without optical filtering cascade effect for a bit error ratio of $10^{-3}$ . This required OSNR level is achieved for the three networks with different granularity and for the two BS analyzed after suitable optimization of the MB-OFDM system parameters. Compared with an ideal MORFEUS network employing ideal rectangular BS, the analyzed networks present an OSNR penalty not exceeding 2.5 dB. A required OSNR penalty of 1 dB due to optical filtering cascade is obtained after six nodes with band filtering, for BS with a second order super-Gaussian shape.
References
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