Network coding for WDM all-optical networks.

摘要

Network coding is a relatively new communication paradigm in which intermediate nodes in a network combine and process data rather than simply forwarding it along. Using network coding, networks can achieve transmission rates which are not possible with traditional networks. This raising of the ceiling on transmission rates has a potentially huge impact for high-bandwidth communications networks such as optical wavelength-division-multiplexing networks, but researchers have only just begun to examine how network coding can be provided in the optical domain. This dissertation attempts to bridge this gap by investigating the application of network coding to all-optical multicast.;A number of challenges stand in the way of applying network coding to optical networks such as coarse bandwidth granularity which does not lend itself to having data easily divided over many different communication channels. Also, by definition, network coding requires the processing of data at intermediate nodes. Typically, in order to perform the necessary operations, the optical signal must undergo optical-electrical-optical (OEO) conversion so that it can be stored and processed in the electronic domain before being retransmitted on the optical medium. This OEO conversion undermines many of the benefits of optical networking, and so it should be avoided when possible. Thus, any computation must be completed by photonic circuits which have limited processing capabilities.;In this dissertation, we address these challenges. We consider the problem of finding efficient routes to use with network coding in the context of coarse bandwidth. We also study the effectiveness of using network coding for optical-layer dedicated protection of multicast traffic which provides robustness against link failures in the network. We present heuristics for solving both of these problems and compare them with both inefficient optimal methods and non-network coding approaches. We also propose architectures for specialized all-optical circuits capable of performing the processing required for network coding and show how these devices can be effectively deployed in an all-optical multicast network. Our experiments show that our heuristics provide near optimal performance and that network coding provides a moderate improvement in bandwidth efficiency for optical-layer multicast traffic while significantly outperforming existing approaches for dedicated multicast protection.