Approximating the traffic grooming problem
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- 作者：Michele Flammini ; Luca Moscardelli ; Mordechai Shalom ; Shmuel Zaks
- 关键词：Wavelength assignment ; Wavelength division multiplexing (WDM) ; Optical networks ; Add-drop multiplexer (ADM) ; Traffic grooming
- 刊名：Journal of Discrete Algorithms
- 出版年：2008
- 出版时间：September 2008
- 年：2008
- 卷：6
- 期：3
- 页码：472-479
- 全文大小：148 K
文摘
The problem of grooming is central in studies of optical networks. In graph-theoretic terms, this can be viewed as assigning colors to the lightpaths so that at most g of them (g being the grooming factor) can share one edge. The cost of a coloring is the number of optical switches (ADMs); each lightpath uses two ADMs, one at each endpoint, and in case g lightpaths of the same wavelength enter through the same edge to one node, they can all use the same ADM (thus saving g−1 ADMs). The goal is to minimize the total number of ADMs. This problem was shown to be NP-complete for g=1 and for a general g. Exact solutions are known for some specific cases, and approximation algorithms for certain topologies exist for g=1. We present an approximation algorithm for this problem. For every value of g the running time of the algorithm is polynomial in the input size, and its approximation ratio for a wide variety of network topologies—including the ring topology—is shown to be 2lng+o(lng). This is the first approximation algorithm for the grooming problem with a general grooming factor g.