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Journal ArticleDOI

Routing, Spectrum, and Core and/or Mode Assignment on Space-Division Multiplexing Optical Networks [Invited]

01 Jan 2017-Journal of Optical Communications and Networking (Optical Society of America)-Vol. 9, Iss: 1
TL;DR: This paper focuses on the routing, spectrum, and core and/or mode assignment (RSCMA) problem for future SDMEONs, and proposes SCMA methods with efficiency and flexibility awareness, exploiting prioritized area concept and crosstalk awareness depending on whether MCF or MMF supports intercore/intermode crosStalk.
Abstract: Elastic optical networks (EONs) are considered to be one of the promising future networks for spectrum flexibility. In conventional wavelength-division multiplexing networks, routing and wavelength assignment is one of the key issues, whereas the routing and spectrum assignment (RSA) problem considerably affects the network performance in EONs. In addition, the data-center traffic and mobile back-haul traffic keeps increasing. To deal with such increasing capacity of applications, space-division multiplexing (SDM) technologies such as multi-core fiber (MCF) and multi-mode fiber (MMF) have been intensively researched. From the network perspective, this paper focuses on the routing, spectrum, and core and/or mode assignment (RSCMA) problem for future SDM-EONs. Introducing MCF or MMF further complicates the RSA problem because the fiber core or mode dimension is newly expanded. In addition, physical impairment caused by MCF or MMF must be considered. In this paper, the target RSCMA problem is first divided into routing and SCMA problems, and a pre-computation method based on the K-shortest path is introduced as the routing solution. Next, we propose SCMA methods with efficiency and flexibility awareness, exploiting prioritized area concept and crosstalk awareness depending on whether MCF or MMF supports intercore/intermode crosstalk. Finally, the paper evaluates and compares the effectiveness of the proposed algorithms with that of representative algorithms.
Citations
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Journal ArticleDOI
TL;DR: This study overviews the state-of-the-art solutions in the scope of planning and operating SDM optical networks in a systematic way as well as to identify some open issues that lack solutions and need to be addressed.

166 citations

Journal ArticleDOI
TL;DR: This paper forms the RSCA problem using a nodearc- based integer linear programming (ILP) method in which the numbers of both variables and constraints are greatly reduced compared with previous ILP methods, thereby leading to a significant improvement in convergence efficiency.
Abstract: In this paper, we focus on the static routing, spectrum, and core assignment (RSCA) problem in spacedivision multiplexing (SDM)-based elastic optical networks (EONs) with multi-core fiber (MCF). In RSCA problems, it is a challenging task to control the inter-core interference, called inter-core crosstalk (XT), within an acceptable level and simultaneously maximize the spectrum utilization. We first consider XT in a worst interference scenario (i.e., XTunaware), which can simplify the RSCA problem. In this scenario, we formulate the RSCA problem using a nodearc- based integer linear programming (ILP) method in which the numbers of both variables and constraints are greatly reduced compared with previous ILP methods, thereby leading to a significant improvement in convergence efficiency. Then, we consider the XT strictly (i.e., XT-aware) and formulate the problem using a mixed integer linear programming (MILP) method, which is an extension of the above node-arc-based ILP method. It is more suitable for different XT thresholds and/or geographically large networks, in that it has a higher degree of generalizability. Finally, we propose an XT-aware-based heuristic algorithm. The simulation results demonstrate that our heuristic algorithm achieves higher spectrum efficiency, higher degree of generalizability, and higher computational efficiency than the existing heuristic algorithm(s).

91 citations


Cites background from "Routing, Spectrum, and Core and/or ..."

  • ...In contrast to the routing and spectrum assignment (RSA) problem in EONs with SMF, SDM-EONs with MCF have introduced some new features that make the RSCA problem more challenging....

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  • ...To satisfy the strongly increasing future traffic demand, the space-division multiplexing (SDM) technique has recently been proposed, and it is considered to be a promising technology for overcoming the physical limitations of SMF by using multi-core fiber (MCF), multi-element fiber (MEF), multi-/few-mode fiber (MMF/FMF), and their combinations [4]....

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  • ...In the traditional WDM systems with SMF, several parallel WDM systems can increase system capacity, but they also increase system cost and energy consumption, leading to the result that the cost and energy consumption remain the same per bit [5]....

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  • ...In contrast to the RSA problem with SMF, which should satisfy the constraints of spectrum continuity, contiguity, and non-overlapping, the XT constraint should be taken into account in the RSCA problem with MCF when assigned the spectral resources, i.e., FSs....

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  • ...However, the growth in the transmission capacity of standard single-mode fiber (SMF) has dramatically slowed because the transmission capacity per fiber is close to the nonlinear Shannon limit of the existing SMF [2,3]....

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Journal ArticleDOI
TL;DR: A crosstalk aware core, mode, and spectrum assignment (CA-CMSA) strategy is presented and simulation results show that the resource allocation algorithm based on LM can improve resource utilization without increasing total connection set-up time and be the best choice for the resource assignment in SDM networks with FM-MCFs.
Abstract: Recently, network traffic has been growing exponentially and almost reached the physical capacity limit of single mode fibers. Space division multiplexing (SDM) is a promising technology to overcome the looming fiber capacity crunch. Especially, few-mode multi-core fibers (FM-MCFs) can aggregate multiple cores into one fiber and two or more modes can be transmitted in one core, which can greatly increase the capacity yet introduce crosstalk constraints including inter- and intra-core crosstalk. To our best knowledge, there is no accurate crosstalk calculation model study in SDM optical networks with FM-MCFs. To address this issue, we first introduce the machine learning into the crosstalk prediction phase and propose a novel crosstalk estimation model (CEM) exploiting the beam propagation method called CEM-beam propagation method (BPM)-machine learning (ML), which can be used to evaluate the crosstalk during the design for the resource allocation scheme. Then, a crosstalk aware core, mode, and spectrum assignment (CA-CMSA) strategy is presented. The simulation results for crosstalk estimation at the wavelength level indicate that the crosstalk at lower frequencies is less than that at higher frequencies. Thus, the lower frequencies are always the first choice in the spectrum resource assignment phase. In addition, for our specific training set, the Levenberg-Marquardt (LM) algorithm based on machine learning performs better on the training, including regression values measurement and time consumption. The simulation results of the proposed CA-CMSA scheme also show that the resource allocation algorithm based on LM can improve resource utilization without increasing total connection set-up time. Thus, it will be the best choice for the resource assignment in SDM networks with FM-MCFs.

64 citations


Cites methods from "Routing, Spectrum, and Core and/or ..."

  • ...[10] proposed a XT-aware CMSA method in SDM-EONs with 7-core 3-mode transmission, but the used XT estimation model is only suitable for MCFs....

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  • ...Works on XT-aware RA algorithms have been also studied in [8]–[10], whereas Rottondi et al....

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Journal ArticleDOI
TL;DR: A dynamic lightpath routing algorithm called adaptive routing with back-to-back regeneration (ARBR) is developed, which is evaluated in comparison to other reference methods and shows that the proposed algorithm outperforms the reference ones in terms of the BBP metric.
Abstract: We focus on dynamic lightpath provisioning in translucent spectrally spatially flexible optical networks (SS-FONs) operating with multi-core fibers and realizing spectral super-channel transmission, in which flexible signal regeneration achieved with transceivers operating in back-to-back (B2B) configurations and modulation conversion is allowed. For optimized allocation of limited spectrum and transceiver resources, we develop a dynamic lightpath routing algorithm called adaptive routing with back-to-back regeneration (ARBR), which we evaluate in comparison to other reference methods. Using the ARBR algorithm, we study potential performance gains in terms of bandwidth blocking probability (BBP) in such flexible network scenarios. To this end, we analyze three alternative scenarios that differ in the way in which dynamic translucent lightpath connections are provisioned, namely a reference scenario in which the use of regenerators is minimized and the modulation conversion is not allowed, and two other scenarios with intentional B2B regeneration. The results of extensive simulation experiments run on two representative network topologies show that the proposed algorithm outperforms the reference ones in terms of the BBP metric. Moreover, the fully flexible B2B regeneration with modulation conversion can be beneficial in terms of both spectrum and transceiver resource utilization, resulting in lower BBP than other scenarios.

50 citations


Cites methods from "Routing, Spectrum, and Core and/or ..."

  • ...The inter-core XT is considered in several works on RSSA, either by using its worst-case estimation [9,10], by applying a best-effort XT avoidance mechanism [11,17,18], or by assuming its strict evaluation [18]....

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  • ...Note that we are not considering prioritized area-based methods [18], which are designed to operate on a small variety of request sizes....

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  • ...[18], the authors propose a prioritized areas method, which is designed based on statistical characteristics of request sizes in bottleneck links and aims at the reduction of resource fragmentation....

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Journal ArticleDOI
TL;DR: Extensive simulation experiments performed in realistic network scenarios indicate that the utilized XT estimation methodology has a significant impact on network performance, with the precise XT approach favored over the worst-case XT strategy.
Abstract: We focus on the problem of crosstalk-aware lightpath provisioning in a dynamic, spectrally and spatially flexible optical network, in which spectral super-channels are carried over multi-core fibers with distance-adaptive transmission. The problem involves establishing a lightpath for a connection such that the inter-core crosstalk (XT) between the new lightpath and any exiting lightpaths does not cause the quality of transmission of any of these light-paths to be below an acceptable level. To this end, we analyze and compare two broad classes of schemes that aim to ensure acceptable XT levels in the network. The first is based on static/worst-case XT, whereas the second uses dynamic/ precise XT estimation. These methods are implemented in a dynamic XT-aware routing, spatial mode, and spectrum allocation algorithm that solves the lightpath-provisioning problem efficiently with the goal of minimizing bandwidth blocking. Extensive simulation experiments performed in realistic network scenarios indicate that the utilized XT estimation methodology has a significant impact on network performance, with the precise XT approach favored over the worst-case XT strategy.

48 citations

References
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Journal ArticleDOI
TL;DR: This article proposes a novel, spectrum- efficient, and scalable optical transport network architecture called SLICE, which enables sub-wavelength, superwa wavelength, and multiple-rate data traffic accommodation in a highly spectrum-efficient manner, thereby providing a fractional bandwidth service.
Abstract: The sustained growth of data traffic volume calls for an introduction of an efficient and scalable transport platform for links of 100 Gb/s and beyond in the future optical network. In this article, after briefly reviewing the existing major technology options, we propose a novel, spectrum- efficient, and scalable optical transport network architecture called SLICE. The SLICE architecture enables sub-wavelength, superwavelength, and multiple-rate data traffic accommodation in a highly spectrum-efficient manner, thereby providing a fractional bandwidth service. Dynamic bandwidth variation of elastic optical paths provides network operators with new business opportunities offering cost-effective and highly available connectivity services through time-dependent bandwidth sharing, energy-efficient network operation, and highly survivable restoration with bandwidth squeezing. We also discuss an optical orthogonal frequency-division multiplexing-based flexible-rate transponder and a bandwidth-variable wavelength cross-connect as the enabling technologies of SLICE concept. Finally, we present the performance evaluation and technical challenges that arise in this new network architecture.

1,489 citations

Journal ArticleDOI
TL;DR: A concept of a novel adaptation scheme in SLICE called distance-adaptive spectrum resource allocation, which can save more than 45 percent of required spectrum resources for a 12-node ring network, is presented.
Abstract: The rigid nature of current wavelength-routed optical networks brings limitations on network utilization efficiency. One limitation originates from mismatch of granularities between the client layer and the wavelength layer. The recently proposed spectrum-sliced elastic optical path network (SLICE) is expected to mitigate this problem by adaptively allocating spectral resources according to client traffic demands. This article discusses another limitation of the current optical networks associated with worst case design in terms of transmission performance. In order to address this problem, we present a concept of a novel adaptation scheme in SLICE called distance-adaptive spectrum resource allocation. In the presented scheme the minimum necessary spectral resource is adaptively allocated according to the end-to-end physical condition of an optical path. Modulation format and optical filter width are used as parameters to determine the necessary spectral resources to be allocated for an optical path. Evaluation of network utilization efficiency shows that distance-adaptive SLICE can save more than 45 percent of required spectrum resources for a 12-node ring network. Finally, we introduce the concept of a frequency slot to extend the current frequency grid standard, and discuss possible spectral resource designation schemes.

831 citations


"Routing, Spectrum, and Core and/or ..." refers methods in this paper

  • ...2) Configuration of Prioritized Areas: In the proposed method, prioritized areas are designed based on statistical characteristics of bottleneck links....

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Journal ArticleDOI
TL;DR: 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.

732 citations

Book ChapterDOI
25 Oct 2010
TL;DR: 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 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. Using algorithms developed in our previous works, we evaluate the spectrum utilization gains that can be obtained by utilizing the elastic bandwidth allocation of OFDM, when compared to a traditional WDM network.

537 citations


"Routing, Spectrum, and Core and/or ..." refers background in this paper

  • ...Thus, distanceadaptive spectrum assignment in an EON conserves the spectrum resources [5]....

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  • ...On the other hand, when a long optical path is required, the network selects a spectrally inefficient modulation format such as binary phase shift keying (BPSK) because of the lower SNR....

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Journal ArticleDOI
TL;DR: The simulation results have demonstrated that the proposed HSMR schemes can effectively reduce the bandwidth blocking probability (BBP) of dynamic RMSA, as compared to two benchmark algorithms that use single-path routing and split spectrum.
Abstract: Empowered by the optical orthogonal frequency-division multiplexing (O-OFDM) technology, flexible online service provisioning can be realized with dynamic routing, modulation, and spectrum assignment (RMSA). In this paper, we propose several online service provisioning algorithms that incorporate dynamic RMSA with a hybrid single-/multi-path routing (HSMR) scheme. We investigate two types of HSMR schemes, namely HSMR using online path computation (HSMR-OPC) and HSMR using fixed path sets (HSMR-FPS). Moreover, for HSMR-FPS, we analyze several path selection policies to optimize the design. We evaluate the proposed algorithms with numerical simulations using a Poisson traffic model and two mesh network topologies. The simulation results have demonstrated that the proposed HSMR schemes can effectively reduce the bandwidth blocking probability (BBP) of dynamic RMSA, as compared to two benchmark algorithms that use single-path routing and split spectrum. Our simulation results suggest that HSMR-OPC can achieve the lowest BBP among all HSMR schemes. This is attributed to the fact that HSMR-OPC optimizes routing paths for each request on the fly with considerations of both bandwidth utilizations and lengths of links. Our simulation results also indicate that the HSMR-FPS scheme that use the largest slots-over-square-of-hops first path-selection policy obtains the lowest BBP among all HSMR-FPS schemes. We then investigate the proposed algorithms' impacts on other network performance metrics, including network throughput and network bandwidth fragmentation ratio. To the best of our knowledge, this is the first attempt to consider dynamic RMSA based on both online path computation and offline path computation with various path selection policies for multipath provisioning in O-OFDM networks.

446 citations


"Routing, Spectrum, and Core and/or ..." refers background in this paper

  • ...The prioritized area is divided into blocks, each of which is the same size as the corresponding frequency slots....

    [...]