Research The Problem Of Large File Transfers With Time Constraints In Optical Networks

With the development of information technology and the deepening of information degree, the requests of the capacity and the quality and variety of quality for communication are become higher. For its huge potentials in enormous bandwidth resource, lower loss and power etc, the optical communication technology has become a research hotspot in the industry and academia. On the other hand, the high developments of distributed computing and real time systems have given higher requirements for the large files transmitting in optical networks. This transfers process often involved the aggregating of files included large scale data which distributed in different locations and it will affect the data store and the performance of systems, so how to minimize the time that needed to complete the huge number of large files transfers is one of the subjects need to be solved in the development of modern networks.In this paper, we mainly research the problem of large files transfer with time constraints in WDM wavelength-routed optical network. That is, the file need to be transferred arrived in network with some distributing and our purpose is expect these large files can complete the transfers process as soon as possible, which can improve the systems'performance. Based on this problem, we first analysis the routing and wavelength assignment (RWA) problem and the file scheduling problem, which are related to the solving of our problem. And then, we proposed some effective heuristic algorithms to solve our large files transmitting problem.Since our research problem is a NP-hard problem, the computational complexity for the optimal solution is very high and general heuristic algorithms can only get some feasible solutions for it. For the sake of further analysis, firstly, we use the knowledge of graph and queuing theory to abstract our study problem and obtain its mathematic model. Secondly, we acquired the lower bound of our problem's optimal solution using the method of subgradient algorithm based on Lagrange Relaxation, which will help us to further analyze the research problem and the heuristic algorithms proposed to solve the problem.In order to compare the performance of algorithms proposed to solve our research problem, a Java-based simulator is also proposed. By simulation, we can find that the Subgradient algorithm based on LR can get better results of the file transmitting time than the heuristic algorithms, and with the theorem of Lagrangian Bounding Principle we can know that value get by the LR method is a lower bound on the optimal value.