Elastic Bandwidth Allocation in Flexible OFDM-Based Optical Networks - (Invited Paper)
Elastic Bandwidth Allocation in Flexible OFDM-Based Optical Networks - (Invited Paper)
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DOI：
10.1007/978-3-642-30376-0_36
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发表时间：
2010-10
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影响因子：
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通讯作者：
K. Christodoulopoulos
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作者：
K. Christodoulopoulos
正交频分复用（OFDM）由于其良好的频谱效率、灵活性和对损伤的容忍度，最近被提出作为用于光网络的调制技术。我们考虑OFDM光网络的规划问题，在这里我们给出了一个流量矩阵，其中包括所要求的传输速率的连接服务。通过使用可变数量的OFDM子载波弹性地分配频谱并选择适当的调制水平，考虑到传输距离，为连接提供其请求的速率。针对传统WDM网络中典型的路由和波长分配（RWA）问题，提出了路由、调制水平和频谱分配（RMLSA）问题，证明了RMLSA问题也是NP完全问题，并给出了解决RMLSA问题的各种算法。并提出了一种分解方法，将RMLSA分解为路由和调制级以及频谱分配两个子问题，依次求解。我们还提出了一个启发式算法，服务连接一个接一个，并使用它来解决规划问题，依次服务于交通矩阵中的所有连接。在顺序算法中，我们研究了两种策略，用于定义连接的顺序。我们还使用模拟退火元启发式算法来获得更好的排序。我们研究所提出的算法的性能，通过仿真实验和评估的频谱利用率的好处，可以通过利用OFDM弹性带宽分配，相比传统的WDM网络。
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, 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.