Análise de utilização de WLANs universitárias

A recente aposta das universidades europeias nas redes locais sem fios - Wireless Local Area Networks (WLANs), como forma de disponibilizar à comunidade académica um serviço de mobilidade, trouxe inúmeras vantagens, mas é de extrema importância perceber até que ponto é que os seus utilizadores tiram proveito desta tecnologia e qual é o seu comportamento. Neste trabalho foram analisadas as WLANs de dois campi universitários pertencentes às Universidades do Minho e de Vigo. O estudo realizado tem por objectivo identificar padrões de comportamento dos utilizadores e o grau de utilização dos recursos de rede, respondendo à questão: qual a utilização efectiva das WLANs em análise? Os resultados deste trabalho, aqui reportados para o caso da Universidade do Minho, demonstram que o local de acesso tem influência no número de utilizadores associados, no volume de tráfego gerado, no número e duração das sessões, fornecendo importantes indicadores para o planeamento, dimensionamento e investimento nas WLANs universitárias

The Critical Neighbourhood Range for Asymptotic Overlay Connectivity in Dense Ad Hoc Networks

peer reviewedWe define, for an overlay built on top of an ad hoc network, a simple criterion for neighbourhood: two overlay nodes are neighbours if and only if there exists a path between them of at most R hops, and R is called the (overlay) neighbourhood range. A small R may result in a disconnected overlay, while an unnecessarily large R would generate extra control traffic. We are interested in the minimum R ensuring overlay connectivity, the so-called critical R. We derive a necessary and sufficient condition on R to achieve asymptotic connectivity of the overlay almost surely, i.e. connectivity with probability 1 when the number of overlay nodes tends to infinity, under the hypothesis that the underlying ad hoc network is itself asymptotically almost surely connected. This condition, though asymptotic, sheds some light on the relation linking the critical R to the number of nodes n, the normalized radio transmission range r and the overlay density D (i.e., the proportion of overlay nodes). This condition can be considered as an approximation when the number of nodes is large enough. Since r is considered as a function of n, we are able to study the impact of topology control mechanisms, by showing how the shape of this function impacts the critical R.PAI MOTIO

Buffer Sizing for 802.11 Based Networks

We consider the sizing of network buffers in 802.11 based networks. Wireless networks face a number of fundamental issues that do not arise in wired networks. We demonstrate that the use of fixed size buffers in 802.11 networks inevitably leads to either undesirable channel under-utilization or unnecessary high delays. We present two novel dynamic buffer sizing algorithms that achieve high throughput while maintaining low delay across a wide range of network conditions. Experimental measurements demonstrate the utility of the proposed algorithms in a production WLAN and a lab testbed.Comment: 14 pages, to appear on IEEE/ACM Transactions on Networkin

Characterising University WLANs within Eduroam Context

The eduroam initiative is assuming an ever growing relevance in providing a secure, worldwide roaming access within the university WLAN context. Although several studies have focused on educational WLAN traffic characterisation, the increasing variety of devices, mobility scenarios and user applications, motivate assessing the effective use of eduroam in order to sustain consistent network planning and deployment. Based on recent WLAN traffic traces collected at the University of Minho (Portugal) and University of Vigo (Spain), the present work contributes for identifying and characterising patterns of user behaviour regarding, for instance, the location and activity sector of users. The results of data analysis quantify the impact of network access location on the number of associated users, on the number and duration of sessions and corresponding traffic volumes. The results also illustrate to what extent users take advantage of mobility in the WLAN. Complementing the analysis on a monthly basis, a fine grain study of WLAN traffic is provided through the identification of users' behaviour and patterns in small timescales

Characterization of Internet Traffic in UUM Wireless Networks

The development in communication technology and the propagation of mobile devices, lightweight, with built-in, high-speed radio access in wireless are making wireless access to the Internet the popular situation rather than a wire line. Whereas, the growth of the wireless network with additional mobile devices in the UUM and increasing number of users led to slow wireless connection. Therefore, understanding the behavior of traffic analysis helps us to develop, manage WLAN technology, and deploy. It help us to apply our workload analysis results to issues in wireless network deployment, such as capacity planning, and potential network optimizations, such as algorithms for load balancing across multiple Access Points (APs) in a wireless network. The trace composes of two parts: firstly, one that connects to the core switch in computer center which is connected with the distribution switches that link the Access Point (APs) with the wireless network at campus, and secondly, another one for the measurement of bulk data transfers and interactive data exchange between two nodes in UUM library, which had been initiated at that time. This thesis investigates the performance network and users' behavior in UUM wireless network

Peace Driving: Case Studies of Wi-Fi Usage

Wireless networking technologies, under the umbrella of the IEEE 802.11 suite of standards and commonly referred to as Wi-Fi, is now commonplace technology in both the home and office. In this work, we present the results of studies into wireless networking uptake and security within two town communities in the UK. Our work concentrates on the geographical positioning of wireless access points (APs) and the security measures used to protect these liberating technologies from unwanted misuse, often referred to as war driving, we employ the title peace driving, for wireless networking surveying which aims to address security issues in wi-fi networks. The results from our study show significant uptake of wireless networking in both the residential and business areas surveyed. The number of access points present in some residential areas is large, and given the relatively small distances between access points there is undoubtedly traffic which is crossing private boundaries. These findings are corroborated across both the communities which were studied. We suggest that similar sized and constituent communities are representative of others in the UK and find similar trends between the two studied as part of this work

Understanding the WiFi usage of university students

In this work, we analyze the use of a WiFi network deployed in a large-scale technical university. To this extent, we leverage three weeks of WiFi traffic data logs and characterize the spatio-temporal correlation of the traffic at different granularities (each individual access point, groups of access points, entire network). The spatial correlation of traffic across nearby access points is also assessed. Then, we search for distinctive fingerprints left on the WiFi traffic by different situations/conditions; namely, we answer the following questions: Do students attending a lecture use the wireless network in a different way than students not attending a lecture?, and Is there any difference in the usage of the wireless network during architecture or engineering classes? A supervised learning approach based on Quadratic Discriminant Analysis (QDA) is used to classify empty vs. occupied rooms and engineering vs. architecture lectures using only WiFi traffic logs with promising results

Channel Sampling Strategies for Monitoring Wireless Networks

Monitoring the activity on an IEEE 802.11 network is useful for many applications, such as network management, optimizing deployment, or detecting network attacks. Deploying wireless sniffers to monitor every access point in an enterprise network, however, may be expensive or impractical. Moreover, some applications may require the deployment of multiple sniffers to monitor the numerous channels in an 802.11 network. In this paper, we explore sampling strategies for monitoring multiple channels in 802.11b/g networks. We describe a simple sampling strategy, where each channel is observed for an equal, predetermined length of time, and consider applications where such a strategy might be appropriate. We then introduce a sampling strategy that weights the time spent on each channel according to the number of frames observed on that channel, and compare the two strategies under experimental conditions