Secure Routing in Wireless Mesh Networks

Wireless mesh networks (WMNs) have emerged as a promising concept to meet the challenges in next-generation networks such as providing flexible, adaptive, and reconfigurable architecture while offering cost-effective solutions to the service providers. Unlike traditional Wi-Fi networks, with each access point (AP) connected to the wired network, in WMNs only a subset of the APs are required to be connected to the wired network. The APs that are connected to the wired network are called the Internet gateways (IGWs), while the APs that do not have wired connections are called the mesh routers (MRs). The MRs are connected to the IGWs using multi-hop communication. The IGWs provide access to conventional clients and interconnect ad hoc, sensor, cellular, and other networks to the Internet. However, most of the existing routing protocols for WMNs are extensions of protocols originally designed for mobile ad hoc networks (MANETs) and thus they perform sub-optimally. Moreover, most routing protocols for WMNs are designed without security issues in mind, where the nodes are all assumed to be honest. In practical deployment scenarios, this assumption does not hold. This chapter provides a comprehensive overview of security issues in WMNs and then particularly focuses on secure routing in these networks. First, it identifies security vulnerabilities in the medium access control (MAC) and the network layers. Various possibilities of compromising data confidentiality, data integrity, replay attacks and offline cryptanalysis are also discussed. Then various types of attacks in the MAC and the network layers are discussed. After enumerating the various types of attacks on the MAC and the network layer, the chapter briefly discusses on some of the preventive mechanisms for these attacks.Comment: 44 pages, 17 figures, 5 table

Markov Decision Processes with Applications in Wireless Sensor Networks: A Survey

Wireless sensor networks (WSNs) consist of autonomous and resource-limited devices. The devices cooperate to monitor one or more physical phenomena within an area of interest. WSNs operate as stochastic systems because of randomness in the monitored environments. For long service time and low maintenance cost, WSNs require adaptive and robust methods to address data exchange, topology formulation, resource and power optimization, sensing coverage and object detection, and security challenges. In these problems, sensor nodes are to make optimized decisions from a set of accessible strategies to achieve design goals. This survey reviews numerous applications of the Markov decision process (MDP) framework, a powerful decision-making tool to develop adaptive algorithms and protocols for WSNs. Furthermore, various solution methods are discussed and compared to serve as a guide for using MDPs in WSNs

On Security and Reliability using Cooperative Transmissions in Sensor Networks

Recent work on cooperative communications has demonstrated benefits in terms of improving the reliability of links through diversity and/or increasing the reach of a link compared to a single transmitter transmitting to a single receiver (single-input single-output or SISO). In one form of cooperative transmissions, multiple nodes can act as virtual antenna elements and provide such benefits using space-time coding. In a multi-hop sensor network, a source node can make use of its neighbors as relays with itself to reach an intermediate node, which will use its neighbors and so on to reach the destination. For the same reliability of a link as SISO, the number of hops between a source and destination may be reduced using cooperative transmissions. However, the presence of malicious or compromised nodes in the network impacts the use of cooperative transmissions. Using more relays can increase the reach of a link, but if one or more relays are malicious, the transmission may fail. In this paper, we analyze this problem to understand the conditions under which cooperative transmissions may fare better or worse than SISO transmissions

On Security and reliability using cooperative transmissions in sensor networks

Cooperative transmissions have received recent attention and research papers have demonstrated their benefits for wireless networks. Such benefits include improving the reliability of links through diversity and/or increasing the reach of a link compared to a single transmitter transmitting to a single receiver (single-input single-output or SISO). In one form of cooperative transmissions, multiple nodes can act as virtual antenna elements and provide diversity gain or range improvement using space-time coding. In a multi-hop ad hoc or sensor network, a source node can make use of its neighbors as relays with itself to reach an intermediate node with greater reliability or at a larger distance than otherwise possible. The intermediate node will use its neighbors in a similar manner and this process continues till the destination is reached. Thus, for the same reliability of a link as SISO, the number of hops between a source and destination may be reduced using cooperative transmissions as each hop spans a larger distance. However, the presence of ma-licious or compromised nodes in the network impacts the benefits obtained with cooperative transmissions. Using more relays can increase the reach of a link, but if one or more relays are malicious, the transmission may fail. However, the relationships between the number of relays, the number of hops, and success probabilities are not trivial to determine. In this paper, we analyze this problem to understand the conditions under which cooperative transmissions fare better or worse than SISO transmissions. We take into consideration additional parameters such as the path-loss exponent and provide a framework that allows us to evaluate the conditions when cooperative transmissions are better than SISO transmissions. This analysis provides insights that can be employed before resorting to simulations or experimentation. © Springer Science+Business Media, LLC 2012

A Survey on Wireless Sensor Network Security

Wireless sensor networks (WSNs) have recently attracted a lot of interest in the research community due their wide range of applications. Due to distributed nature of these networks and their deployment in remote areas, these networks are vulnerable to numerous security threats that can adversely affect their proper functioning. This problem is more critical if the network is deployed for some mission-critical applications such as in a tactical battlefield. Random failure of nodes is also very likely in real-life deployment scenarios. Due to resource constraints in the sensor nodes, traditional security mechanisms with large overhead of computation and communication are infeasible in WSNs. Security in sensor networks is, therefore, a particularly challenging task. This paper discusses the current state of the art in security mechanisms for WSNs. Various types of attacks are discussed and their countermeasures presented. A brief discussion on the future direction of research in WSN security is also included.Comment: 24 pages, 4 figures, 2 table

Cooperative communication in wireless networks: algorithms, protocols and systems

Current wireless network solutions are based on a link abstraction where a single co-channel transmitter transmits in any time duration. This model severely limits the performance that can be obtained from the network. Being inherently an extension of a wired network model, this model is also incapable of handling the unique challenges that arise in a wireless medium. The prevailing theme of this research is to explore wireless link abstractions that incorporate the broadcast and space-time varying nature of the wireless channel. Recently, a new paradigm for wireless networks which uses the idea of 'cooperative transmissions' (CT) has garnered significant attention. Unlike current approaches where a single transmitter transmits at a time in any channel, with CT, multiple transmitters transmit concurrently after appropriately encoding their transmissions. While the physical layer mechanisms for CT have been well studied, the higher layer applicability of CT has been relatively unexplored. In this work, we show that when wireless links use CT, several network performance metrics such as aggregate throughput, security and spatial reuse can be improved significantly compared to the current state of the art. In this context, our first contribution is Aegis, a framework for securing wireless networks against eavesdropping which uses CT with intelligent scheduling and coding in Wireless Local Area networks. The second contribution is Symbiotic Coding, an approach to encode information such that successful reception is possible even upon collisions. The third contribution is Proteus, a routing protocol that improves aggregate throughput in multi-hop networks by leveraging CT to adapt the rate and range of links in a flow. Finally, we also explore the practical aspects of realizing CT using real systems.PhDCommittee Chair: Sivakumar, Raghupathy; Committee Member: Ammar, Mostafa; Committee Member: Ingram, Mary Ann; Committee Member: Jayant, Nikil; Committee Member: Riley, Georg