Low Complexity All-Optical Network Coder Architecture

Network coding, a networking paradigm in which different pieces of data are coded together at various points along a transmission, has been proposed for providing a number of benefits to networks including increased throughput, robustness, and security. For optical networks, the potential for using network coding to provide survivability is especially noteworthy as it may be possible to allow for the ultra-fast recovery time of dedicated protection schemes with the bandwidth efficiency of shared protection schemes. However, the need to perform computations at intermediate nodes along the optical route leads to the undesirable necessity of either electronically buffering and processing the data at intermediate nodes or outfitting the network with complex photonic circuits capable of performing the computations entirely within the optical domain. In this paper, we take the latter approach but attempt to mitigate the impact of the device complexity by proposing a low-complexity, all-optical network coder architecture. Our design provides easily scalable, powerful digital network coding capabilities at the optical layer, and we show that existing network coding algorithms can be adjusted to accommodate it

Classifying Networks For Network Coding

Network coding is a relatively recent development in the realm of maximizing information transfer in communications and computer networks. Traditional networks operate by simply storing and forwarding data along. Network coding, however, allows intermediate network nodes to combine data using arithmetic operations. In many instances, this can lead to more efficient use of network resources. Since there is a significant throughput input in some networks, some studies have been done on what kinds of networks will benefit from coding. A coding advantage is defined as a situation where a network coded graph has a lower cost to send given information per unit time session than the same un-coded graph. It has been proven that for two simple single-sender-single-receiver communication sessions that a graph must have one of two special graph-theoretic structures called the butterfly and grail in order to yield a coding advantage. We decided to focus our efforts on a different traffic scenario: a multicast session with a single sender and multiple receivers. Through our research we proved that a multicast-version of the butterfly network structure is needed within a single session multicast with two sinks and one source in order to gain a coding advantage. We also performed a simulation-based study in order to study the structures of multicast sessions with a larger number of receivers. The study involved the random generation of networks using several graph generation techniques. We also considered a variety of different edge-weighting constraints. Given a particular graph with set edge weights, the coding advantage problem was modeled as a linear program and run through the simulator to determine if a coding advantage was gained. Based on visual inspection of these results, it appears that variations of the multicast butterfly are ultimately the dominant structure allowing for a coding advantage. We also found that many types of random networks only very rarely resulted in a coding advantage. Only the graphs generated using the rectangular grid method showed a coding advantage, with a coding advantage percentage of 0.005% for 4 sinks in a 30 node network, with the coding advantage percentage going up as the number of sinks within the network increased

Building A Thriving CS Program In A Small Liberal Arts College

In this paper we describe several techniques that have helped increase enrollment in the computer science program from 23 computer science majors in 2008 to 42 computer science majors in 2010 – an increase of 82.6%. We discuss issues related to curriculum, programming assignments, and professor-student interactions that have made the discipline more attractive and manageable to a variety of students within the setting of a small liberal arts college

Design Of An All-Optical WDM Lightpath Concentrator

A design of a nonblocking, all-optical lightpath concentrator using wavelength exchanging optical crossbars and WDM crossbar switches is presented. The proposed concentrator is highly scalable, cost-efficient, and can switch signals in both space and wavelength domains without requiring a separate wavelength conversion stage

Selection Of Switching Sites In All-Optical Network Topology Design

In this paper, we consider the problem of topology design for both unprotected and one-link protected all-optical networks. We investigate the problem of selecting switching sites to minimize total cost of the network. The cost of an optical network is expressed as a sum of three main factors: the site cost, the link cost, and the switch cost. For unprotected networks with linear cost model, we present a mixed integer linear programming (MILP) formulation of the problem. We also present an efficient heuristic to approximate the solution. The experimental results show good performance of the linear cost model heuristic. In 16% of the experiments with 10 nodes network topologies, the linear cost model heuristic had no error. Moreover, for 54% and 86% of the experiments with 10 nodes network topologies, the linear cost model heuristic’s solution is within 2% and 5% of its optimal value respectively. Finally, we extend our approach to one-link protected networks, and present an efficient survivable heuristic, and representative experimental results

Physics Opportunities with Meson Beams

Over the past two decades, meson photo- and electro-production data of unprecedented quality and quantity have been measured at electromagnetic facilities worldwide. By contrast, the meson-beam data for the same hadronic final states are mostly outdated and largely of poor quality, or even nonexistent, and thus provide inadequate input to help interpret, analyze, and exploit the full potential of the new electromagnetic data. To reap the full benefit of the high-precision electromagnetic data, new high-statistics data from measurements with meson beams, with good angle and energy coverage for a wide range of reactions, are critically needed to advance our knowledge in baryon and meson spectroscopy and other related areas of hadron physics. To address this situation, a state of-the-art meson-beam facility needs to be constructed. The present paper summarizes unresolved issues in hadron physics and outlines the vast opportunities and advances that only become possible with such a facility.Comment: 46 pages, 10 figures, 4 table