Kuang-Ching Wang

An OpenFlow Testbed for the Evaluation of Vertical Handover Decision Algorithms in Heterogeneous Wireless Networks

This paper details a framework that leverages Software Defined Networking (SDN) features to provide a testbed for evaluating handovers for IPv4 heterogeneous wireless networks. The framework is intended to be an extension to the Global Environment for Network Innovations (GENI) testbed, but the essence of the framework can be applied on any OpenFlow (OF) enabled network. Our goal is to enable researchers to evaluate vertical handover decision algorithms using GENI resources, open source software, and low cost commodity hardware. The framework eliminates the triangle routing problem experienced by other previous IPv4-compatible IP mobility solutions. This paper provides an overview of the testbed framework, implementation details for our installation using GENI WiMAX resources, and a discussion of future work.

A Framework for Performance Evaluation of Communication Alternatives for Intelligent Transportation Systems

The communications infrastructure is critical for effective and efficient operation of intelligent transportation system (ITS) functions. Relatively large investments from the public sector are usually required to construct and maintain or provide leasing fee to private telecommunication companies for such infrastructure. Consequently, a rigorous analysis and evaluation of communication alternatives is of utmost importance. This research sought to develop a systematic framework and associated platform that will facilitate the evaluation of the communication alternatives for ITS. The framework includes identifying alternative architectures, such as distributed, centralized, or a combination of both, and identifying communication mediums including wired, wireless, or a combination of both. This article presents, as a part of the framework, important measures of effectiveness (MOE) for making objective comparisons between alternatives based on the performance of the communication systems related to ITS. A simulation platform that integrated a traffic and communication simulator was used for efficiently evaluating communication alternatives with different architecture and mediums by generating important MOEs. A case study was performed for a test network in Greenville, South Carolina. The proposed evaluation framework identified four communication alternatives, namely, the centralized wired, distributed wired, centralized wireless, and distributed wireless, to generate the selected MOEs, such as throughput, delivery ratio, and throughput cost ratios, for comparing and analyzing these alternatives.

GENI Cinema: An SDN-Assisted Scalable Live Video Streaming Service

This paper introduces GENI Cinema (GC), a system that provides a scalable live video streaming service based on dynamic traffic steering with software defined networking (SDN) and demand driven instantiation of video relay servers in NSF GENIs distributed cloud environments. While the service can be used to relay a multitude of video content, its initial objective is to support live video streaming of educational content such as lectures and seminars among university campuses. Users on any campus would bootstrap video upload or download via a public Web portal and, for scalability, have the video delivered seamlessly across the network over one or multiple paths selected and dynamically controlled by GC. The architecture aims to provide a framework for addressing several well-known limitations of video streaming in todays Internet, where little control is available for controlling forwarding paths of on demand live video streams. GC utilizes GENIs distributed cloud servers to host on-demand video servers/relays and its Open Flow SDN to achieve seamless video upload/download and optimization of forwarding paths in the network core. This paper presents the architecture and an early prototype of the basic GC framework, together with some initial performance measurement results.

Wireless Communication Alternatives for Intelligent Transportation Systems: A Case Study

Communication systems are the basis of every effective and reliable traffic control and management application. While cellular-based communication through commercial carriers is widely used for online traffic management applications, public agencies have also begun to consider other technologies, such as WiFi and WiMAX. Most such agencies still seek additional guidelines for the selection of suitable wireless options for different traffic control and management applications under different physical and environmental conditions. Performance and reliability are among the most important parameters to be considered when examining wireless communication options for traffic control and management applications. The authors first conducted interviews with selected traffic agencies regarding their experiences with performance of wireless communication infrastructure, as well as their interests and plans on future expansion. Next, they conducted a thorough literature review focusing on various wireless technologies that could be used in an intelligent transportation system environment. Last, the authors conducted a case study in which a section of the South Carolina Department of Transportation traffic camera system was wirelessly connected via either WiFi or WiMAX network architecture. This case study followed the proposed network design process presented in the article using WiFi and WiMAX technologies to support a traffic surveillance system that considered coverage range and two different network topologies: mesh/ad hoc (devices forward data to neighboring devices to reach the destination) and infrastructure (devices send data to an access point directly). The network simulator ns-2 was used to assess the average throughput that each camera can receive in different network topologies. Throughput/cost analysis of WiFi and WiMAX mesh and infrastructure topologies indicated that for given number of devices, a mesh network has better throughput for every dollar spent than infrastructure based topology. This article provides a foundation for further investigation of WiFi and WiMAX performance and reliability under different network topologies. Findings from this research will benefit transportation agencies and other stakeholders in evaluating and selecting wireless communication options and network topologies for various traffic control and management applications.

The Widening Gulf between Genomics Data Generation and Consumption: A Practical Guide to Big Data Transfer Technology

In the last decade, high-throughput DNA sequencing has become a disruptive technology and pushed the life sciences into a distributed ecosystem of sequence data producers and consumers. Given the power of genomics and declining sequencing costs, biology is an emerging “Big Data” discipline that will soon enter the exabyte data range when all subdisciplines are combined. These datasets must be transferred across commercial and research networks in creative ways since sending data without thought can have serious consequences on data processing time frames. Thus, it is imperative that biologists, bioinformaticians, and information technology engineers recalibrate data processing paradigms to fit this emerging reality. This review attempts to provide a snapshot of Big Data transfer across networks, which is often overlooked by many biologists. Specifically, we discuss four key areas: 1) data transfer networks, protocols, and applications; 2) data transfer security including encryption, access, firewalls, and the Science DMZ; 3) data flow control with software-defined networking; and 4) data storage, staging, archiving and access. A primary intention of this article is to orient the biologist in key aspects of the data transfer process in order to frame their genomics-oriented needs to enterprise IT professionals.

Field Performance Study of a Regional WiMAX Network for Intelligent Transportation System Applications

Of the various advanced wireless communication technologies used for intelligent transportation systems (ITS), WiMAX has recently received much attention because of its potential to provide broadband network connectivity, large coverage areas, quality assurance, and mobile access. However, few studies have focused on the deployment, operational, and performance issues of using WiMAX networks for ITS applications in a real roadway environment. This study performed a field performance evaluation of a regional WiMAX network in West Virginia by using important network metrics, including uplink and downlink throughput, signal strength, and connectivity level. On the basis of performance analysis, this paper discusses the feasibility and suitability of a regional WiMAX network deployment for a wireless sensor-based traffic surveillance system in terms of frequency, power, and client side radio requirements. This study provides an insight into the feasibility of using WiMAX to address ITS applications. It will benefit transportation agencies and other stakeholders to support decision making in the deployment and operation of a WiMAX-based ITS network in the future.

Error pattern analysis for data transmission of wireless sensors on rotating industrial structures

Wireless sensors capable of sensing, processing, and wireless communication have been adopted for monitoring purposes in a variety of contexts, many of which feature challenging radio propagation characteristics. Fast rotating structures are commonly found in mechanical, transportation and energy systems, and the challenges of using wireless sensors on such structures have not been adequately addressed. For wireless sensors on rotating structures, it has been found there is an eminent dependency of packet error rates on rotation speeds, bursty bit errors, periodic variation in received signal strengths, and dominance of multipath effects. Previously, a reliable data transmission approach was developed to recover transmission errors, and it was found that transmission errors have mostly occurred in certain high-error regions. The objective of this study is to utilize the transmission approach to infer the transmission error pattern of such regions. The paper presents a sliding window algorithm for estimating the error region width, and a transmission simulator for studying dependencies among error burst statistics, error region distribution and widths, and accuracy of the rotation speeds. It is concluded that i) the number, width, and distribution of error regions can be inferred from normalized error burst distance distributions, ii) the error burst distance distributions depend sensitively on accuracy of the rotation speed, and iii) the error in speed can be inferred from the error burst distance distributions. The conclusions directly guide future work on transmission error modeling, on-line error pattern inference, and error-avoidant transmission methods for radios on rotating structures.

A distributed wireless sensor network system for transportation safety and security

Given the anticipated increases in highway traffic, the scale and complexity of the traffic infrastructure will continue to grow progressively in time and in distributed geographical areas. To assure transportation efficiency, safety, and security in the presence of such growth, it is critical to identify an infrastructure development methodology that can adapt to expansions while assuring reliable operation for both centralized monitoring and distributed management. In this paper, a wireless sensor network design methodology is presented, aimed at providing effective distributed surveillance, anomaly detection, and coordinated response. The proposed methodology integrates state-of-the-art traffic sensors, with flexibly programmable controller devices that can integrate with the available traffic control equipments. The system methodology provides a paradigm in which sensors and controllers can be progressively incorporated and programmed to autonomously coordinate with peer sensors and a hierarchy of controllers to detect, notify, and react to anomalous events. Since the system can tolerate failure of parts of the system, as the network connectivity continues to increase, the proposed sensor network will have positive implications on evacuation plans during natural disasters or terrorist attacks. To illustrate the design methodology and usage, a simulated system along a freeway corridor in South Carolina was constructed in an integrated microscopic traffic and wireless sensor network simulation platform, in which distributed incident detection and response functions were implemented. The test results, including detection and false alarm rates and wireless communication latencies, are analyzed to identify insights of the systems operation and potential enhancement strategies.

Network Coding for Efficient Broadband Data Delivery in Infrastructure-Based Vehicular Networks with OpenFlow

This paper proposes a system architecture for supporting efficient broadband data delivery in infrastructure based vehicular networks. The proposed approach addresses two major challenges for high throughput data transport from Internet to moving vehicles over infrastructure wireless networks such as todays 4G technologies: difficulty in maintaining stable throughput over high latency wide area paths in core networks; difficulty in maintaining continuous data download across road-side units (RSUs) in the edge. Specifically, the system multicasts network-encoded packets in the core network (wired Internet infrastructure) to multiple selected RSUs, while the RSUs collaborate in disseminating and scheduling delivery of the encoded packets to vehicles. Realizing the overall system requires network coding and multipath forwarding capabilities in the core network, and network decoding support in the vehicles. For network coding to be efficient, however, dynamic control of the forwarding paths of the network coded packets are essential. This paper presents the proposed system architecture, its key components, and how they can be experimentally studied over National Science Foundations Global Environment for Network Innovations (GENI) testbed. Experiments on ProtoGENI testbed show the feasibility and advantages of network coding in core networks.

A Measurement Study on Link Capacity of a High Stress IEEE 802.11b/g Network

The paper presents results from a link capacity measurement study conducted over an IEEE 802.11b/g network with highly stressed radio propagation conditions in a football stadium. Existing capacity studies for IEEE 802.11 networks have considered either stationary or statistical multipath fading channel conditions. In an environment with a high density of people and movement such as in a football stadium or a subway station, the radio characteristics vary much more vibrantly, and their impact on network capacity is not well understood. As a first step to better understand such network characteristics, the study examines the throughput of a mobile terminal over the stadium network in the presence of varying radio conditions due to movement of people and concurrent transmissions by other IEEE 802.11 devices. The study uses a novel approach to quantify network utilization by the experiment terminal as well as other contending terminals, using a recorded packet trace. From the measured utilization, throughput, and signal strengths, key observations made include the fast variations in signal strength due to crowd movement, through puts dependency on signal strength and chosen link rate, and contention with other terminals. Based on the findings, the paper discusses useful insights for performance assessment, protocol enhancements, and improvements in measurement methodology for such networks.