Opportunistic Localization Scheme Based on Linear Matrix Inequality

Enabling self-localization of mobile nodes is an important problem that has been widely studied in the literature. The general conclusions is that an accurate localization requires either sophisticated hardware (GPS, UWB, ultrasounds transceiver) or a dedicated infrastructure (GSM, WLAN). In this paper we tackle the problem from a different and rather new perspective: we investigate how localization performance can be improved by means of a cooperative and opportunistic data exchange among the nodes. We consider a target node, completely unaware of its own position, and a number of mobile nodes with some self-localization capabilities. When the opportunity occurs, the target node can exchange data with in-range mobile nodes. This opportunistic data exchange is then used by the target node to refine its position estimate by using a technique based on Linear Matrix Inequalities and barycentric algorithm. To investigate the performance of such an opportunistic localization algorithm, we define a simple mathematical model that describes the opportunistic interactions and, then, we run several computer simulations for analyzing the effect of the nodes duty-cycle and of the native self-localization error modeling considered. The results show that the opportunistic interactions can actually improve the self-localization accuracy of a strayed node in many different scenarios

Security and Privacy Issues in Wireless Mesh Networks: A Survey

This book chapter identifies various security threats in wireless mesh network (WMN). Keeping in mind the critical requirement of security and user privacy in WMNs, this chapter provides a comprehensive overview of various possible attacks on different layers of the communication protocol stack for WMNs and their corresponding defense mechanisms. First, it identifies the security vulnerabilities in the physical, link, network, transport, application layers. Furthermore, various possible attacks on the key management protocols, user authentication and access control protocols, and user privacy preservation protocols are presented. After enumerating various possible attacks, the chapter provides a detailed discussion on various existing security mechanisms and protocols to defend against and wherever possible prevent the possible attacks. Comparative analyses are also presented on the security schemes with regards to the cryptographic schemes used, key management strategies deployed, use of any trusted third party, computation and communication overhead involved etc. The chapter then presents a brief discussion on various trust management approaches for WMNs since trust and reputation-based schemes are increasingly becoming popular for enforcing security in wireless networks. A number of open problems in security and privacy issues for WMNs are subsequently discussed before the chapter is finally concluded.Comment: 62 pages, 12 figures, 6 tables. This chapter is an extension of the author's previous submission in arXiv submission: arXiv:1102.1226. There are some text overlaps with the previous submissio

A Comparative Study of Wireless Sensor Networks and Their Routing Protocols

Recent developments in the area of micro-sensor devices have accelerated advances in the sensor networks field leading to many new protocols specifically designed for wireless sensor networks (WSNs). Wireless sensor networks with hundreds to thousands of sensor nodes can gather information from an unattended location and transmit the gathered data to a particular user, depending on the application. These sensor nodes have some constraints due to their limited energy, storage capacity and computing power. Data are routed from one node to other using different routing protocols. There are a number of routing protocols for wireless sensor networks. In this review article, we discuss the architecture of wireless sensor networks. Further, we categorize the routing protocols according to some key factors and summarize their mode of operation. Finally, we provide a comparative study on these various protocols

A data-oriented network architecture

In the 25 years since becoming commercially available, the Internet has grown into a global communication infrastructure connecting a significant part of mankind and has become an important part of modern society. Its impressive growth has been fostered by innovative applications, many of which were completely unforeseen by the Internet's inventors. While fully acknowledging ingenuity and creativity of application designers, it is equally impressive how little the core architecture of the Internet has evolved during this time. However, the ever evolving applications and growing importance of the Internet have resulted in increasing discordance between the Internet's current use and its original design. In this thesis, we focus on four sources of discomfort caused by this divergence. First, the Internet was developed around host-to-host applications, such as telnet and ftp, but the vast majority of its current usage is service access and data retrieval. Second, while the freedom to connect from any host to any other host was a major factor behind the success of the Internet, it provides little protection for connected hosts today. As a result, distributed denial of service attacks against Internet services have become a common nuisance, and are difficult to resolve within the current architecture. Third, Internet connectivity is becoming nearly ubiquitous and reaches increasingly often mobile devices. Moreover, connectivity is expected to extend its reach to even most extreme places. Hence, applications' view to network has changed radically; it's commonplace that they are offered intermittent connectivity at best and required to be smart enough to use heterogeneous network technologies. Finally, modern networks deploy so-called middleboxes both to improve performance and provide protection. However, when doing so, the middleboxes have to impose themselves between the communication end-points, which is against the design principles of the original Internet and a source of complications both for the management of networks and design of application protocols. In this thesis, we design a clean-slate network architecture that is a better fit with the current use of the Internet. We present a name resolution system based on name-based routing. It matches with the service access and data retrieval oriented usage of the Internet, and takes the network imposed middleboxes properly into account. We then propose modest addressing-related changes to the network layer as a remedy for the denial of service attacks. Finally, we take steps towards a data-oriented communications API that provides better decoupling for applications from the network stack than the original Sockets API does. The improved decoupling both simplifies applications and allows them to be unaffected by evolving network technologies: in this architecture, coping with intermittent connectivity and heterogenous network technologies is a burden of the network stack

The state of peer-to-peer network simulators

Networking research often relies on simulation in order to test and evaluate new ideas. An important requirement of this process is that results must be reproducible so that other researchers can replicate, validate and extend existing work. We look at the landscape of simulators for research in peer-to-peer (P2P) networks by conducting a survey of a combined total of over 280 papers from before and after 2007 (the year of the last survey in this area), and comment on the large quantity of research using bespoke, closed-source simulators. We propose a set of criteria that P2P simulators should meet, and poll the P2P research community for their agreement. We aim to drive the community towards performing their experiments on simulators that allow for others to validate their results

Advance of the Access Methods

The goal of this paper is to outline the advance of the access methods in the last ten years as well as to make review of all available in the accessible bibliography methods

Optimal joint path computation and rate allocation for real-time traffic

Computing network paths under worst-case delay constraints has been the subject of abundant literature in the past two decades. Assuming Weighted Fair Queueing scheduling at the nodes, this translates to computing paths and reserving rates at each link. The problem is NP-hard in general, even for a single path; hence polynomial-time heuristics have been proposed in the past, that either assume equal rates at each node, or compute the path heuristically and then allocate the rates optimally on the given path. In this paper we show that the above heuristics, albeit finding optimal solutions quite often, can lead to failing of paths at very low loads, and that this could be avoided by solving the problem, i.e., path computation and rate allocation, jointly at optimality. This is possible by modeling the problem as a mixed-integer second-order cone program and solving it optimally in split-second times for relatively large networks on commodity hardware; this approach can also be easily turned into a heuristic one, trading a negligible increase in blocking probability for one order of magnitude of computation time. Extensive simulations show that these methods are feasible in today's ISPs networks and they significantly outperform the existing schemes in terms of blocking probability