Security in heterogeneous wireless networks

The proliferation of a range of wireless devices, from the cheap low power resource starved sensor nodes to the ubiquitous cell phones and PDA\u27s has resulted in their use in many applications. Due to their inherent broadcast nature Security and Privacy in wireless networks is harder than the wired networks. Along with the traditional security requirements like confidentiality, integrity and non-repudiation new requirements like privacy and anonymity are important in wireless networks. These factors combined with the fact that nodes in a wireless network may have different resource availabilities and trust levels makes security in wireless networks extremely challenging. The functional lifetime of sensor networks in general is longer than the operational lifetime of a single node, due to limited battery power. Therefore to keep the network working multiple deployments of sensor nodes are needed. In this thesis, we analyze the vulnerability of the existing key predistribution schemes arising out of the repeated use of fixed key information through multiple deployments. We also develop SCON, an approach for key management that provides a significant improvement in security using multiple key pools. SCON performs better in a heterogeneous environment. We present a key distribution scheme that allows mobile sensor nodes to connect with stationary nodes of several networks. We develop a key distribution scheme for a semi ad-hoc network of cell phones. This scheme ensures that cell phones are able to communicate securely with each other when the phones are unable to connect to the base station. It is different from the traditional ad hoc networks because the phones were part of a centralized network before the base station ceased to work. This allows efficient distribution of key material making the existing schemes for ad hoc networks ineffective. In this thesis we present a mechanism for implementing authenticated broadcasts which ensure non-repudiation using identity based cryptography. We also develop a reputation based mechanism for the distributed detection and revocation of malicious cell phones. Schemes which use the cell phone for secure spatial authentication have also been presented

Towards Opportunistic Data Dissemination in Mobile Phone Sensor Networks

Recently, there has been a growing interest within the research community in developing opportunistic routing protocols. Many schemes have been proposed; however, they differ greatly in assumptions and in type of network for which they are evaluated. As a result, researchers have an ambiguous understanding of how these schemes compare against each other in their specific applications. To investigate the performance of existing opportunistic routing algorithms in realistic scenarios, we propose a heterogeneous architecture including fixed infrastructure, mobile infrastructure, and mobile nodes. The proposed architecture focuses on how to utilize the available, low cost short-range radios of mobile phones for data gathering and dissemination. We also propose a new realistic mobility model and metrics. Existing opportunistic routing protocols are simulated and evaluated with the proposed heterogeneous architecture, mobility models, and transmission interfaces. Results show that some protocols suffer long time-to-live (TTL), while others suffer short TTL. We show that heterogeneous sensor network architectures need heterogeneous routing algorithms, such as a combination of Epidemic and Spray and Wait

A survey of localization in wireless sensor network

Localization is one of the key techniques in wireless sensor network. The location estimation methods can be classified into target/source localization and node self-localization. In target localization, we mainly introduce the energy-based method. Then we investigate the node self-localization methods. Since the widespread adoption of the wireless sensor network, the localization methods are different in various applications. And there are several challenges in some special scenarios. In this paper, we present a comprehensive survey of these challenges: localization in non-line-of-sight, node selection criteria for localization in energy-constrained network, scheduling the sensor node to optimize the tradeoff between localization performance and energy consumption, cooperative node localization, and localization algorithm in heterogeneous network. Finally, we introduce the evaluation criteria for localization in wireless sensor network

Gravitational Clustering: A Simple, Robust and Adaptive Approach for Distributed Networks

Distributed signal processing for wireless sensor networks enables that different devices cooperate to solve different signal processing tasks. A crucial first step is to answer the question: who observes what? Recently, several distributed algorithms have been proposed, which frame the signal/object labelling problem in terms of cluster analysis after extracting source-specific features, however, the number of clusters is assumed to be known. We propose a new method called Gravitational Clustering (GC) to adaptively estimate the time-varying number of clusters based on a set of feature vectors. The key idea is to exploit the physical principle of gravitational force between mass units: streaming-in feature vectors are considered as mass units of fixed position in the feature space, around which mobile mass units are injected at each time instant. The cluster enumeration exploits the fact that the highest attraction on the mobile mass units is exerted by regions with a high density of feature vectors, i.e., gravitational clusters. By sharing estimates among neighboring nodes via a diffusion-adaptation scheme, cooperative and distributed cluster enumeration is achieved. Numerical experiments concerning robustness against outliers, convergence and computational complexity are conducted. The application in a distributed cooperative multi-view camera network illustrates the applicability to real-world problems.Comment: 12 pages, 9 figure