Optimal design of optical WDM networks

光网络在骨干计算机网络中有着广泛的应用。随着互联网流量总量的快速增长，如何合理利用网络资源，降低新建网络的资金成本和网络的运营成本显得尤为重要。本研究将使用现代运筹学技术并开发算法，这些算法将a)降低部署光网络的成本，b)提高处理用户数据通信请求时网络的有效使用，以及c)提高此类网络的弹性。全光波分复用网络存在的一个问题是，随着光纤长度的增加，光信号的质量会下降。在下一代网络中，开发以经济有效的方式恢复信号质量的方法变得非常重要。如果采用一种有效的策略来最小化能够恢复光信号质量的“再生”节点的数量，则可以显著降低部署光网络的成本。如果现有资源能够处理更多的数据通信请求，则可以提高WDM网络的效率。使用先进的运筹学工具，我们的研究将在减少再生节点数量和提高网络效率方面提高技术水平。这样的网络中的每根光纤都承载着大量的数据，因此网络中单个光纤的故障，即使是短时间的故障，也会造成重大的经济影响。我们将开发相对便宜且仍然保证容错操作的方案。为了更有效地利用网络带宽，人们正在研究正交频分复用技术（OFDM）。拟议的研究将开发算法，使更多的数据通信请求得到考虑。本文将考虑三个问题：1)如果所有的数据通信请求都是事先已知的，如何以最有效的方式处理它们；2)如果请求是动态处理的，如何最好地处理它们；3)如何在OFDM网络中加入容错。

Optical networks are widely used in backbone computer networks. Due to the rapid increase of the totalvolume of internet traffic, it is very important to reduce the capital cost of setting up new networks and the operating cost of the networks by making optimum use of network resources. This investigation will use modern Operations Research techniques and develop algorithms that will a) reduce the cost of deploying optical networks, b) improve the efficient use of the network in handling the requests from users for data communication, and c) improve the resiliency of such networks. One problem with all-optical wavelength division multiplexed networks is the fact that the quality of optical signals degrade when the fiber length increases. It has become important, in the next generation networks, to develop methods to recover signal quality in a cost-effective manner. The cost of deploying an optical network is significantly reduced if an efficient strategy is used to minimize the number of "regenerating" nodes which can restore the quality of optical signals. The efficiency of a WDM network is improved if more requests for data communication can be handled with existing resources. Using advanced Operations Research tools, our research will improve the state of the art, both in terms of reducing the number of regenerating nodes used and in improving the efficiency of the network. Each optical fiber in such a network carries an enormous amount of data, so that the failure of a single fiber in a network, even for short durations, has significant economic impact. We will develop schemes that are relatively inexpensive and still guarantee fault-tolerant operations. Orthogonal Frequency-Division Multiplexing (OFDM) is being investigated to make more efficient use of the network bandwidth. The proposed research will develop algorithms to enable more requests for data communication to be considered.Three problems will be considered - i) if all the requests for data communication are known in advance how to handle them in the most efficient manner, ii) if the requests are to be handled dynamically how to handle them best and iii) how to incorporate fault tolerance in an OFDM network.