Group: crawdad - with tag dartmouth_campus [101 articles]

Abstract

In this paper, we present a routing scheme that exploits knowledge about the behavior of mobile sinks within a network of data sources to minimize energy consumption and network congestion. For delay-tolerant network applications, we propose to route data not to the sink directly, but to send it instead to a relay node along an announced or predicted path of the mobile node that is close to the data source. The relay node will stash the information until the ...

Abstract

Opportunistic network is a type of delay tolerant networks (DTN) where network communication opportunities appear opportunistic. In this study, we investigate opportunistic network scenarios based on public network traces, and our contributions are the following: First, we identify the censorship issue in network traces that usually leads to strongly skewed distribution of the measurements. Based on this knowledge, we then apply the Kaplan-Meier Estimator to calculate the survivorship of network measurements, which is used in designing our proposed censorship removal algorithm ...

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We study the problem of interference detection in dense Wi-Fi deployments, which are a reality in most modern metropolitan areas. Interference among neighbor Wi-Fi cells stems from the anarchic deployment of Wi-Fi access points (APs) and the fact that only few APs can operate at the same location on non-overlapping frequencies. Detection of interference conditions is the first step towards its mitigation. We follow a client-centric approach, where wireless clients monitor and report Wi-Fi AP presence. We focus on the security ...

Abstract

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Abstract

Realistic mobility models are fundamental to evaluate the performance of protocols in mobile ad hoc networks. Unfortunately, there are no mobility models that capture the non-homogeneous behaviors in both space and time commonly found in reality, while at the same time being easy to use and analyze. Motivated by this, we propose a time-variant community mobility model, referred to as the TVC model, which realistically captures spatial and temporal correlations. We devise the communities that lead to skewed location visiting preferences, ...

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Abstract Unauthorized 802.11 wireless access points (APs), or rogue APs, such as those brought into a corporate campus by employees, pose a security threat as they may be poorly managed or insufficiently secured. An attacker in the vicinity may easily get onto the internal network through a rogue AP, bypassing all perimeter security measures. Existing detection solutions do not work well for detecting rogue APs configured as routers that are protected by WEP, 802.11 i, or other security measures. In this ...

Abstract

The choice of a mobility model has a significant impact on the performance of mobile network simulations. In order to accurately evaluate performance, it is important to mimic the environment in which the mobile network will be deployed. Thus, using realistic mobility models for simulation environments are preferred to synthetic models. Historically, however, unrealistic movement models have been mostly used due to their simplicity and mathematical tractability. Recently, a few mobility models have been derived from real user traces; these models, ...

Abstract

Two link models are used to generate a social proximity network topology, used to support delay tolerant networking in human networks. It is shown how the link models produce graphs with fundamentally different properties, though based on the same underlying social mobility data. These properties influence how messages are routed, among other global attributes. Network design must consider link models as a fundamental aspect of the architecture. ...

Abstract

The ubiquity of mobile devices has brought forth the concept of participatory sensing, whereby ordinary citizens can now contribute and share information from the urban environment. However, such applications introduce a key research challenge: preserving the location privacy of the individuals contributing data. In this paper, we propose the use of microaggregation, a concept used for protecting privacy in databases, as a solution to this problem. We compare microaggregation with tessellation, the current state-of-the-art, and demonstrate that each technique has its ...

Abstract

Providing on-demand video streaming services to large numbers of nodes in mobile wireless networks is a challenging task. We propose MOVi (mobile opportunistic video-on-demand), a mobile peer-to-peer video-on-demand application based on ubiquitous WiFi enabled devices such as smartphones and Ultra Mobile PCs. MOVi poses new challenges in on-demand video streaming caused by limited wireless communication range, user mobility and variable user population density. MOVi addresses these challenges by exploiting the opportunistic mix use of downlink and direct peer-to-peer communication to significantly ...

Abstract

The use of sophisticated techniques is essential to detect and identify the presence of botnet flows, but these techniques can be expensive in computational and memory resources. A critical first pass is to filter out all traffic that is highly unlikely to be part of a botnet, allowing the more complex algorithms to run over a much smaller set of flows. This paper presents our studies and experience in filtering flows to reduce the botnet search space, and shows that a ...

Abstract

The delay-tolerant mobile sensor network (DTMSN) distinguishes itself from conventional sensor networks by several unique characteristics, such as nodal mobility, sparse connectivity, delay tolerability, and fault tolerability. Being an opportunistic network where the communication links exist with certain probabilities only and thus become the scarcest resource, the routing metrics that have been commonly adopted in conventional networks do not reflect this unique network resource of DTMSN. Therefore, they may lead to poor network performance or even failure if used for routing ...

Abstract

Abstract  Wireless mesh networks have attracted increasing attention and deployment as a high-performance and low-cost solution to last-mile broadband Internet access. Traffic routing plays a critical role in determining the performance of a wireless mesh network. To investigate the best routing solution, existing work proposes to formulate the mesh network routing problem as an optimization problem. In this problem formulation, traffic demand is usually implicitly assumed as static and known a priori. Contradictorily, recent studies of wireless network traces show that the ...

Abstract

Mobility models are used to simulate and evaluate the performance of mobile wireless systems and the algorithms and protocols at the basis of them. The definition of realistic mobility models is one of the most critical and, at the same time, difficult aspects of the simulation of applications and systems designed for mobile environments. There are essentially two possible types of mobility patterns that can be used to evaluate mobile network protocols and algorithms by means of simulations: traces and synthetic ...

Abstract

In this paper we study the use of a semantically rich storage model to fulfill the data transmission requirements of challenged networking environments, which are characterised by long delays and frequent communication disruptions. Practical experience shows us that the highly successful data abstractions of mainstream storage systems (e.g. monolithic file representation) operate poorly in emergent networking environments such as Delay Tolerant Networks (DTNs); short contact times do not allow for complete file or bundle transmissions. We have ported and integrated two ...

Abstract

The mobility prediction problem is defined as guessing a mobile node's next access point as it moves through a wireless network. Those predictions help take proactive measures in order to guarantee a given quality of service. Prediction agents can be divided into two main categories: agents related to a specific terminal (responsible for anticipating its own movements) and those related to an access point (which predict the next access point of all the mobiles connected through it). This paper aims at ...

Abstract

We present a stochastic model for a social network, where new actors may join the network, existing actors may become inactive and, at a later stage, reactivate themselves. Our model captures the evolution of the network, assuming that actors attain new relations or become active according to the preferential attachment rule. We derive the mean-field equations for this stochastic model and show that, asymptotically, the distribution of actors obeys a power-law distribution. In particular, the model applies to social networks such ...

Abstract

Anomaly detection (AD) sensors compute behavior profiles to recognize malicious or anomalous activities. The behavior of a host is checked continuously by the AD sensor and an alert is raised when the behavior deviates from its behavior profile. Unfortunately, the majority of AD sensors suffer from high volumes of false alerts either maliciously crafted by the host or originating from insufficient training of the sensor. We present a cluster-based AD sensor that relies on clusters of behavior profiles to identify anomalous ...

Abstract

Campus and enterprise wireless networks are increasingly characterized by ubiquitous coverage and rising traffic demands. Efficiently assigning channels to access points (APs) in these networks can significantly affect the performance and capacity of the WLANs. The state-of-the-art approaches assign channels statically, without considering prevailing traffic demands. In this paper, we show that the quality of a channel assignment can be improved significantly by incorporating observed traffic demands at APs and clients into the assignment process. We refer to this as ...

Abstract

Mobile users' demand for omnipresent, reliable, and high throughput services from a wireless LAN infrastructure has led a significant number of enterprises and public bodies to deploy large-scale high-density IEEE 802.11-based WLANs. These WLANs feature several hundreds to thousands of APs that are managed centrally and are typically dimensioned for peak user demands. Unfortunately, peak demands are occasional and WLANs often under-utilized. Using measurements from two different WLANs we show that the under-utilization of WLANs leads to a significant energy wastage, ...

Abstract

Abstract  Enterprise wireless local area networks (WLANs) that consist of a high-density of hundreds to thousands of access points (APs) are being deployed rapidly in corporate offices and university campuses. The primary purpose of these deployments is to satisfy user demands for high bandwidth, mobility, and reliability. However, our recent study of two such WLANs showed that these networks are rarely used at their peak capacity, and the majority of their resources are frequently idle. In this paper, we bring to attention ...

Abstract

Anticipating user mobility can be a critical feature for today's mobile systems. We introduce a novel location predictor which incorporates knowledge of a user's potential future locations to improve prediction accuracy. Such future knowledge is often available through contextual sources such as a user's calendar, e-mail, or instant messaging conversations. Simulation results show that our future knowledge leveraging location predictor can improve prediction accuracy by 3% to 95\\\\\\\\ over history-only Markov predictors, depending on the amount of future knowledge that is ...

Abstract

The testing of the performance of opportunistic communication protocols and applications is usually done through simulation as i) deployments are expensive and should be left to the final stage of the development process, and ii) the number of varying parameters in thesesystems is so high that it would be very hard to conduct thorough testing of all the functionality within a single deployment. Therefore, protocols and applications are often plugged into mobility simulators to test their performance; however, until recently, most ...

Abstract

Wireless self-organizing networks such as mesh networks strive hard to get rid of mobility and radio propagation effects. Links – the basic elements ensuring connectivity in wireless networks – are impacted first from them. But what happens if one could mitigate these effects by forecasting the links' future states? In this paper, we propose XCoPred (using Cross-Correlation to Predict), a pattern matching based scheme to predict link quality variations. XCoPred does not require the use of any external hardware, it relies ...

Abstract

Rapid WLAN deployment has led to various research challenges and scenarios. In this paper we come up with a technique to classify users into social groups and then use this information to investigate the usage behavior of these groups. Grouping of users can be done based on diverse parameters like gender, major or other interest groups. In this paper we show the general methodology used to accomplish WLAN user groupings with an example of grouping by gender in a major university ...

Abstract

Performance of short TCP transfers, e.g., Web browsing, has a direct impact on the way users perceive the health of their Internet access. It is a common belief that TCP performs better with large than with short transfers, as the latters are more likely to time-out and their duration is dominated by the RTT. In this paper, we revisit the performance of short TCP transfers. We highlight the interplay between TCP and the application on top. We show that while losses ...

Abstract

Campus wireless LANs (WLANs) are complex systems with hundreds of access points (APs) and thousands of users. Their performance analysis calls for realistic models of their elements, which can be input to simulation and testbed experiments but also taken into account for theoretical work. However, only few modeling results in this area are derived from real measurement data, and rarely do they provide a complete and consistent view of entire WLANs. In this work, we address this gap relying on extensive ...

Abstract

Wireless LAN administrators often have to deal with the problem of sporadic client congestion in popular locations within the network. Existing approaches that relieve congestion by balancing the traffic load are encumbered by the modifications that are required to both access points and clients. We propose cell breathing, a well-known concept in cellular telephony, as a load balancing mechanism to handle client congestion in a wireless LAN. We develop power management algorithms for controlling the coverage of access points to handle ...

Abstract

Recent years have witnessed significant growth in the adoption of portable wireless communication and computing devices (e.g., laptops, PDAs, smart phones) and large-scale deployment of wireless networks (e.g., cellular, WLANs). We envision that future usage of mobile devices and services will be highly personalized. Users will incorporate these new technologies into their daily lives, and the way they use new devices and services will reflect their personality and lifestyle. Therefore it is imperative to study and characterize the fundamental structure of ...