Frame Capture in IEEE 802.11p Vehicular Networks

IEEE 802.11p is the new standard proposed by the IEEE for wireless connectivity in a vehicular context. It can be used by Advanced Driver Assistance Systems (ADAS) and Intelligent Transport Systems (ITS) to make vehicles aware of the traffic around them and increase vehicle safety with applications like cooperative cruise control, assisted merging and assisted lane switching. It is an amendment to the 802.11 standards family, with a physical layer based on Orthogonal Frequency Division Multiplexing (OFDM) similar to 802.11a. It is designed operate in a harsh environment. The increased degree of movement in a vehicular network creates Doppler shift, for example when vehicles connect to roadside units. Also, the cars on the road generate a significantcant amount of scattering and fast fading effects. This Doppler shift and other effects are accounted for in the design of the physical layer of 802.11p

A Dynamically Refocusable Sampling Infrastructure for 802.11 Networks

The edge of the Internet is increasingly wireless. Enterprises large and small, homeowners, and even whole cities have deployed Wi-Fi networks for their users, and many users never need to--- or never bother to--- use the wired network. With the advent of high-throughput wireless networks (such as 802.11n) some new construction, even of large enterprise build- ings, may no longer be wired for Ethernet. To understand Internet traffic, then, we need to understand the wireless edge. Measuring Wi-Fi traffic, however, is challenging. It is insufficient to capture traffic in the access points, or upstream of the access points, because the activity of neighboring networks, ad hoc networks, and physical interference cannot be seen at that level. To truly understand the MAC-layer behavior, we need to capture frames from the air using Air Monitors (AMs) placed in the vicinity of the network. Such a capture is always a sample of the network activity, since it is physically impossible to capture a full trace: all frames from all channels at all times in all places. We have built a monitoring infrastructure that captures frames from the 802.11 network. This infrastructure includes several channel sampling strategies that will capture repre- sentative traffic from the network. Further, the monitoring infrastructure needs to modify its behavior according to feedback received from the downstream consumers of the captured traffic in case the analysis needs traffic of a certain type. We call this technique refocusing . The coordinated sampling technique improves the efficiency of the monitoring by utilizing the AMs intelligently. Finally, we deployed this measurement infrastructure within our Computer Science building to study the performance of the system with real network traffic

Experimenting with commodity 802.11 hardware: overview and future directions

The huge adoption of 802.11 technologies has triggered a vast amount of experimentally-driven research works. These works range from performance analysis to protocol enhancements, including the proposal of novel applications and services. Due to the affordability of the technology, this experimental research is typically based on commercial off-the-shelf (COTS) devices, and, given the rate at which 802.11 releases new standards (which are adopted into new, affordable devices), the field is likely to continue to produce results. In this paper, we review and categorise the most prevalent works carried out with 802.11 COTS devices over the past 15 years, to present a timely snapshot of the areas that have attracted the most attention so far, through a taxonomy that distinguishes between performance studies, enhancements, services, and methodology. In this way, we provide a quick overview of the results achieved by the research community that enables prospective authors to identify potential areas of new research, some of which are discussed after the presentation of the survey.This work has been partly supported by the European Community through the CROWD project (FP7-ICT-318115) and by the Madrid Regional Government through the TIGRE5-CM program (S2013/ICE-2919).Publicad

From Map to Dist: the Evolution of a Large-Scale Wlan Monitoring System

The edge of the Internet is increasingly becoming wireless. Therefore, monitoring the wireless edge is important to understanding the security and performance aspects of the Internet experience. We have designed and implemented a large-scale WLAN monitoring system, the Distributed Internet Security Testbed (DIST), at Dartmouth College. It is equipped with distributed arrays of “sniffers” that cover 210 diverse campus locations and more than 5,000 users. In this paper, we describe our approach, designs and solutions for addressing the technical challenges that have resulted from efficiency, scalability, security, and management perspectives. We also present extensive evaluation results on a production network, and summarize the lessons learned

Large-scale Wireless Local-area Network Measurement and Privacy Analysis

The edge of the Internet is increasingly becoming wireless. Understanding the wireless edge is therefore important for understanding the performance and security aspects of the Internet experience. This need is especially necessary for enterprise-wide wireless local-area networks (WLANs) as organizations increasingly depend on WLANs for mission- critical tasks. To study a live production WLAN, especially a large-scale network, is a difficult undertaking. Two fundamental difficulties involved are (1) building a scalable network measurement infrastructure to collect traces from a large-scale production WLAN, and (2) preserving user privacy while sharing these collected traces to the network research community. In this dissertation, we present our experience in designing and implementing one of the largest distributed WLAN measurement systems in the United States, the Dartmouth Internet Security Testbed (DIST), with a particular focus on our solutions to the challenges of efficiency, scalability, and security. We also present an extensive evaluation of the DIST system. To understand the severity of some potential trace-sharing risks for an enterprise-wide large-scale wireless network, we conduct privacy analysis on one kind of wireless network traces, a user-association log, collected from a large-scale WLAN. We introduce a machine-learning based approach that can extract and quantify sensitive information from a user-association log, even though it is sanitized. Finally, we present a case study that evaluates the tradeoff between utility and privacy on WLAN trace sanitization

EVALUATING THE USE OF SNMP AS A WIRELESS NETWORK MONITORING TOOL FOR IEEE 802.11 WIRELESS NETWORKS

The increasing popularity of wireless networks has led to instances of high utilization and congestion, some of which have resulted in an interruption of network service. A thorough understanding of how IEEE 802.11 wireless networks operate is crucial to predicting and preventing future interruptions. There have been many studies performed on wireless networks. Of those that have captured data from the wireless side, most have used a form of wireless network monitoring known as Vicinity Sniffing (wireless sniffing from a location that is physically close to an access point to be in the broadcast range) as the primary means of capturing data. We believe that with recent advancements, SNMP is now capable of producing reliable results that were previously unattainable. We were presented with several obstacles in our studies, most of which are beliefs that SNMP is inadequate for monitoring IEEE 802.11 wireless networks. The claim is that SNMP provides either aggregated statistics or instantaneous values, and that it cannot report data on a per-device level, which is often desired so that individual details of a network\u27s performance may be analyzed. Although the data is aggregated over some length of time, recent advancements do in fact allow for per-device details. Because of this, we believe that these claims are no longer valid, and that they are hindering the use of a very versatile tool. This study is motivated by the iTiger project which is a research project located at Clemson University. A prototype system has been developed allowing fans attending home football games to interact with a set of web applications using 802.11 enabled smartphones. A driving requirement behind the work presented in this thesis was to develop a framework for monitoring and analyzing the underlying IEEE 802.11 network used by the iTiger system. The work presented is based on a set of controlled experiments conducted in the football stadium. The result of our study will be to show that the latest generation of wireless equipment can provide data that was once thought to be available only from wireless monitoring. Through our analysis, we will provide a proof-of-concept that SNMP is more capable than previously thought and that the results obtained from wireless networks are as accurate, and in some situations even more accurate, than those statistics acquired from using the techniques of Vicinity Sniffing

A Practical guide to understanding wireless networking concepts, security protocols, attack, and safer deployment schemes

With the explosion of wireless networks appearing in buildings, business and educational campuses, and even homes; security is a large concern in order to prevent attempted intrusions and malicious attacks from the retrieval of confidential data. Wireless Fidelity, Wi-Fi for short, does provide security in the form called Wired Equivalent Privacy otherwise simply known as WEP. However cases documenting WEP\u27s security mechanism being breached in legitimate and illegitimate cases have been published and are readily available on the Internet. While wireless networks provide the freedom of mobility for users, this also allows potential hackers to eavesdrop on unsuspecting wireless users. Or worse, one could potentially hijack an access point and gain unauthorized access past the wireless network and then into the wired internal network. Thus an intruder who has hijacked an access point will be able to access critical data while hiding safely outside the building. Knowledge and understanding of wireless networks and of its security is a necessary step to be learnt if wireless networks are to be deployed securely especially in congested urban settings

Analysis of an IEEE 802.11-based protocol for real-time applications in agriculture

La tesi descrive un sistema originale basato sullo standard IEEE 802.11 per il monitoraggio ed il controllo remoto in tempo reale di una macchina agricola attraverso dispositivi commerciali quali smartphones e tablet. Le prestazioni del sistema sono state attentamente caratterizzate, sia dal punto di vista teorico che da quello pratico, tramite numerose sessioni di misure sperimentali. Opportune soluzioni alle problematiche riscontrate sono proposte, evidenziando sostanziali miglioramentiopenEmbargo temporaneo per motivi di segretezza e/o di proprietà dei risultati e informazioni di enti esterni o aziende private che hanno partecipato alla realizzazione del lavoro di ricerca relativo alla tes

Measuring Transmission Opportunities in 802.11 Links

We propose a powerful MAC/PHY cross-layer approach to measuring IEEE 802.11 transmission opportunities in WLAN networks on a per-link basis. Our estimator can operate at a single station and it is able to: 1) classify losses caused by noise, collisions, and hidden nodes; and 2) distinguish between these losses and the unfairness caused by both exposed nodes and channel capture. Our estimator provides quantitative measures of the different causes of lost transmission opportunities, requiring only local measures at the 802.11 transmitter and no modification to the 802.11 protocol or in other stations. Our approach is suited to implementation on commodity hardware, and we demonstrate our prototype implementation via experimental assessments. We finally show how our estimator can help the WLAN station to improve its local performance

Precise Packet Loss Pattern Generation by Intentional Interference

Abstract—Intermediate-quality links often cause vulnerable connectivity in wireless sensor networks, but packet losses caused by such volatile links are not easy to trace. In order to equip link layer protocol designers with a reliable test and debugging tool, we develop a reactive interferer to generate packet loss patterns precisely. By using intentional interference to emulate parameterized lossy links with very low intrusiveness, our tool facilitates both robustness evaluation of protocols and flaw detection in protocol implementation