Distance-adaptive spectrum resource allocation in spectrum-sliced elastic optical path network [Topics in Optical Communications]
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.
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TL;DR: The drivers, building blocks, architecture, and enabling technologies for a whole new elastic optical networking paradigm are described, as well as early standardization efforts.
Abstract: Optical networks are undergoing significant changes, fueled by the exponential growth of traffic due to multimedia services and by the increased uncertainty in predicting the sources of this traffic due to the ever changing models of content providers over the Internet. The change has already begun: simple on-off modulation of signals, which was adequate for bit rates up to 10 Gb/s, has given way to much more sophisticated modulation schemes for 100 Gb/s and beyond. The next bottleneck is the 10-year-old division of the optical spectrum into a fixed "wavelength grid," which will no longer work for 400 Gb/s and above, heralding the need for a more flexible grid. Once both transceivers and switches become flexible, a whole new elastic optical networking paradigm is born. In this article we describe the drivers, building blocks, architecture, and enabling technologies for this new paradigm, as well as early standardization efforts.
1,448 citations
Cites background from "Distance-adaptive spectrum resource..."
...…difficult to transmit over long distances at high spectral efficiency (i.e., how much data rate can be supported for a limited spectral bandwidth) [1]; hence, it becomes beneficial for transceivers to be able to maximize spectral efficiency by adapting to the actual conditions of the network and…...
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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
TL;DR: A tutorial that covers the key aspects of elastic optical networks, and explores the experimental demonstrations that have tested the functionality of the elastic optical network, along with the research challenges and open issues posed by flexible networks.
Abstract: Flexgrid technology is now considered to be a promising solution for future high-speed network design. In this context, we need a tutorial that covers the key aspects of elastic optical networks. This tutorial paper starts with a brief introduction of the elastic optical network and its unique characteristics. The paper then moves to the architecture of the elastic optical network and its operation principle. To complete the discussion of network architecture, this paper focuses on the different node architectures, and compares their performance in terms of scalability and flexibility. Thereafter, this paper reviews and classifies routing and spectrum allocation (RSA) approaches including their pros and cons. Furthermore, various aspects, namely, fragmentation, modulation, quality-of-transmission, traffic grooming, survivability, energy saving, and networking cost related to RSA, are presented. Finally, the paper explores the experimental demonstrations that have tested the functionality of the elastic optical network, and follows that with the research challenges and open issues posed by flexible networks.
547 citations
Cites background or methods from "Distance-adaptive spectrum resource..."
...In the modulation-based spectrum allocation scheme of [12], [58], the necessary minimum spectral resource is adaptively allocated to an optical path....
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...[12] presented, for first time, the method referred to as single slot on the grid approach, see Fig....
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...To overcome the bandwidth fragmentation problem, many RSA approaches [12], [14], [34], [36], [56] have been published....
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...Most of the approaches [12], [14], [34], [36], [50], [55], [56] in the literature perform bandwidth defragmentation after...
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...[12] have presented a distanceadaptive spectrum allocation scheme that adopts a high-level modulation format for long distance paths, and a low-level...
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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
Cites background or methods from "Distance-adaptive spectrum resource..."
...To avoid interference effects between adjacent optical paths, appropriate spectrum separation, implemented by spectrum guardbands, is required [11]....
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...optical path is the sole QoT factor [11], [15], [16] of interest....
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...Moreover, to simplify our analysis, we will assume that a subcarrier always utilizes a constant spectrum GHz, irrespectively of the modulation format [11], [15]....
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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
References
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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
"Distance-adaptive spectrum resource..." refers background or methods in this paper
...Figure 2a illustrates the node and link models used in our numerical simulation, where WXCs are interconnected with 50 km long standard singlemode fiber links with loss of 12.5 dB. In WXCs optical power splitters and bandwidth-variable WSS are utilized in a broadcast-and-select configuration to provide an add-and-drop function for local signals as well as grooming and routing function for transit signals [ 1 ]....
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...In addition, spectrum resource allocation adaptive to the available spectral resources on the route enables highly survivable bandwidth squeezed restoration [ 1 , 4]....
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TL;DR: An overview of the challenges and promises of link adaptation in future broadband wireless networks is given and guidelines to help in the design of robust, complexity/cost-effective algorithms for these future wireless networks are suggested.
Abstract: Link adaptation techniques, where the modulation, coding rate, and/or other signal transmission parameters are dynamically adapted to the changing channel conditions, have emerged as powerful tools for increasing the data rate and spectral efficiency of wireless data-centric networks. While there has been significant progress on understanding the theoretical aspects of time adaptation in LA protocols, new challenges surface when dynamic transmission techniques are employed in broadband wireless networks with multiple signaling dimensions. Those additional dimensions are mainly frequency, especially in multicarrier systems, and space in multiple-antenna systems, particularly multiarray multiple-input multiple-output communication systems. We give an overview of the challenges and promises of link adaptation in future broadband wireless networks. We suggest guidelines to help in the design of robust, complexity/cost-effective algorithms for these future wireless networks.
529 citations
"Distance-adaptive spectrum resource..." refers background in this paper
...The basic idea behind link adaptation technologies is to adjust the transmission parameters, such as modulation and coding levels, to take advantage of prevailing channel conditions [ 5 ]....
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Book•
01 Jan 2005
TL;DR: Digital Modulation of Optical Carrier and Coherent Optical Receivers and Ideal Performance: Impairment to Optical Signal, Nonlinear Phase Noise Compensation, Intrachannel Pulse-to-Pulse Interaction, Multilevel Signaling, Phase-Modulated Soliton Signals, Capacity of Optical Channels as discussed by the authors.
Abstract: Digital Modulation of Optical Carrier.- Coherent Optical Receivers and Ideal Performance.- Impairment to Optical Signal.- Nonlinear Phase Noise.- Compensation of Nonlinear Phase Noise.- Intrachannel Pulse-to-Pulse Interaction.- Wavelength-Division-Multiplexed DPSK Signals.- Multilevel Signaling.- Phase-Modulated Soliton Signals.- Capacity of Optical Channels.
366 citations
05 Mar 2006
TL;DR: In this article, a novel wavelength selective switch (WSS) based on a liquid crystal on silicon (LCOS) switching element is presented, which operates simultaneously at both 50 and 100 GHz channel spacing and is compatible with 40 G transmission requirements.
Abstract: We present a novel wavelength selective switch (WSS) based on a liquid crystal on silicon (LCOS) switching element. The unit operates simultaneously at both 50 and 100 GHz channel spacing and is compatible with 40 G transmission requirements.
298 citations
"Distance-adaptive spectrum resource..." refers methods in this paper
...This functionality can be realized using bandwidth-variable optical filters employing a spatial light modulator, such as liquid crystal on silicon (LCoS), configured with a dispersive element to separate WDM signals [ 9 ]....
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22 Dec 2008
TL;DR: In this article, a novel spectrum-efficient elastic optical path network for 100 Gb/s services and beyond, based on flexible rate transceivers and variable-bandwidth wavelength crossconnects, was proposed.
Abstract: We demonstrated, for the first time, a novel spectrum-efficient elastic optical path network for 100 Gb/s services and beyond, based on flexible rate transceivers and variable-bandwidth wavelength crossconnects.
150 citations