Security is of critical importance for many potential applications of wireless sensor networks. In order to maintain
secure communication throughout the network, it is of vital importance to maintain encryption key freshness by
regularly distributing new keys to all nodes. Distribution of group keys used to encrypt broadcast communication
is expensive, as it is generally achieved via flooding, which taxes the limited battery life available to each node.
We propose LKDT, a lightweight encryption key distribution tree building mechanism with an optional Multi-
Coverage Reduction (MCR) stage to provide a framework by which to distribute keys while reducing power
consumption and broadcast coverage overlap. Additionally, LKDT can configure itself quickly, allowing the base
station to begin updating keys shortly after deployment.
Mobile ad hoc network (MANET) is a radio packet network without dedicated infrastructures. In recent years it has
received tremendous attention because of its self-configuration and self-maintenance capabilities. However, because of
node mobility and shared wireless links, its routing protocol design presents nontrivial challenges such as broadcast storm,
stale route and delay. This paper proposes a location-based route self-recovery technique for source-initiated routing
protocols. The purpose of route self-recovery is to reduce overhead and delay during route maintenance as well as allowing
continuous packet forwarding for fault resilience. The ns-2 based simulation shows throughput and overhead improvements
of source-initiated routing with route self-recovery and in the case of highly dynamic environments and heavy traffic loads,
it is more robust and scalable than other protocols.
Ad hoc networks rely on cooperation in order to operate, but in a resource constrained environment not all nodes
behave altruistically. Selfish nodes preserve their own resources and do not forward packets not in their own self
interest. These nodes degrade the performance of the network, but judicious route selection can help maintain
performance despite this behavior. Many route selection algorithms place importance on shortness of the route
rather than its reliability. We introduce a light-weight route selection algorithm that uses past behavior to judge
the quality of a route rather than solely on the length of the route. It draws information from the underlying
routing layer at no extra cost and selects routes with a simple algorithm. This technique maintains this data
in a small table, which does not place a high cost on memory. History-based route selection's minimalism suits
the needs the portable wireless devices and is easy to implement. We implemented our algorithm and tested it
in the ns2 environment. Our simulation results show that history-based route selection achieves higher packet
delivery and improved stability than its length-based counterpart.
Localization is an important challenge in wireless sensor networks (WSN). Localization usually refers to the process of dynamically determining the position(s) of one or more node(s) in a larger network. The challenge lies in efficiently providing "acceptable" accuracy while conforming to the many constraints of WSNs. We propose a Cluster-based Partial Localization (CPL) to provide efficient localization, where the focus is on providing scalable partial localization suitable to a large and high-density network. CPL utilizes both a computationallyintensive localization technique (non-metric MDS) and a less intensive triangulation to achieve balance between complexity and performance. Clustering is utilized to select a subset of nodes to perform the non-metric MDS localization and then extend to the rest of the network. We show, with simulation results, that CPL will provide a considerable reduction in both computation and communication, while still yielding an acceptable accuracy.
Bluetooth is a promising wireless technology that enables devices to form short-range multihop wireless ad-hoc networks, or personal area networks. However, the Bluetooth scatternet formation is one of the challenges that need to be resolved since the performance of a Bluetooth network depends largely on the scatternet topology used. We first present a height-balanced binary tree, termed ACB-tree for almost-complete-binary tree, that allows two such trees to be combined to create a larger ACB-tree retaining the height-balance requirements. And, then propose a distributed scatternet formation algorithm to create ACB-trees: the generated scatternet is shown to minimize the number of piconets and provide a logarithmic-diameter in the multihop interconnection network. We also present simulations, conducted using Blueware simulator, to provide experimental results to study and compare the performance of the resulting scatternets.
KEYWORDS: Sensors, Sensor networks, Data communications, Data transmission, Data modeling, Energy efficiency, Environmental sensing, Scanning probe microscopy, Data acquisition, Electrical engineering
Disseminating data among sensors is a fundamental operation in
energy-constrained wireless sensor networks. We present a gossip-based adaptive protocol for data dissemination to improve energy efficiency of this operation. To overcome the data implosion problems associated with dissemination operation, our protocol uses meta-data to name the data using high-level data descriptors and negotiation to eliminate redundant transmissions of duplicate data in the network. Further, we adapt the gossiping with data aggregation possibilities in sensor networks. We simulated our data dissemination protocol, and compared it to the SPIN protocol. We find that our protocol improves on the energy consumption by about 20% over others, while improving significantly over the data dissemination rate of gossiping.
This paper proposes an improved form of authentication security for Mobile IPv6 called buddy enhanced return routability. Enhanced return routability builds on the foundation of return routability and extends that technique through the use of stochastic route selection for authentication messages. Theoretical work and simulation results show that enhanced return routability strengthens authentication security without adding restrictive overhead requirements or opening up new security holes.
Packet dropping in Mobile Ad-hoc Networks could be a result of wireless link errors, congestion, or malicious packet drop attack. Current techniques for detecting malicious behavior either do not consider congestion in the network or are not able to detect in real time. Further more, they usually work at network layer. In this paper, we propose a TCP-Manet protocol, which reacts to congestion like TCP Reno protocol, and has additional capability to distinguish among congestion, wireless link error, and malicious packet drop attack. It is an end-to-end mechanism that does not require additional modifications to the nodes in the network. Since it is an extension of existing TCP protocol, it is compatible with existing protocols. It works in conjunction with the network layer and an unobtrusive monitor to assist the network in the detection and characterization of the nature of the behavior. Experimental results show that TCP-Manet has the same performance as that of TCP-Reno in wired network, and performs better in wireless ad-hoc networks in terms of throughput while having good detection effectiveness.
KEYWORDS: Network security, Data storage, Wireless communications, Information security, Data analysis, Mobile devices, Computer networks, Computer security, Switches, Relays
Advances in wireless communications and the proliferation of mobile computing devices has led to the rise of a new type of computer network: the ad-hoc wireless network. Ad-hoc networks are characterized by a lack of fixed infrastructure, which give ad-hoc networks a great deal of flexibility, but also increases the risk of security problems. In wired networks, key pieces of network infrastructure are secured to prevent unauthorized physical access and tampering. Network administrators ensure that everything is properly configured and are on-hand to fix problems and deal with intrusions. In contrast, the nodes in an ad-hoc network are responsible for routing and forwarding data in the network, and there are no network administrators to handle potential problems. This makes an ad-hoc network more vulnerable to a misconfigured, faulty, or compromised node. We propose a means for a node in an ad-hoc network to detect and handle these malicious nodes by comparing data available to the routing protocol, such as cached routes in Dynamic Source Routing, ICMP messages, and transport layer information, such as TCP timeouts. This data can then be used along with network probes to isolate the malicious node.
The upcoming Ultra-wide-band (UWB) radio technology holds great promise for revolutionizing wireless communications. UWB radios transmit using precise, very short (e.g. picosecond) impulses spread over a very large bandwidth (up to a few Ghz). The significant advantages of this technology are low-power operation, mitigated multi-path fading effects, high bit-rates and unique precise position/timing location ability. However, one of the drawbacks of this technology, in its current state, is the high channel acquisition time, i.e. the time for a transmitter and receiver to achieve bit synchronization. This tends to be quite high, of the order of a few milli-seconds. Hence, it is important for current medium access control (MAC) protocol design to consider the impact of acquisition time. In this paper, we study the performance of two standard MAC protocols - the distributed CSMA/CA protocol and the centralized TDM protocol in the context of UWB wireless local area networks. We study effects of varying packet frame sizes and packet arrival rates and present a quantification of the impact of acquisition time on overall performance.
KEYWORDS: Internet, Signal processing, Network architectures, Mobile communications, Computer science, Control systems, Process control, Electrical engineering, Communication engineering, Computer engineering
There is an emerging interest in integrating mobile wireless communication
with the Internet based on the Ipv6 technology. Many issues introduced by
the mobility of users arise when such an integration is attempted. This paper addresses the problem of mobility management, i.e., that of tracking the current IP addresses of mobile terminals and sustaining active IP connections as mobiles move. The paper presents some architectural and mobility management options for integrating wireless access to the Internet. We then present performance results for Mobile IPv4, route optimization and Mobile IPv6.
Current handoff techniques in integrated services wireless networks focus on the mobile-to-fixed node handoff and have not addressed issues regarding mobile-to-mobile handoff. Virtual connection extension based mobile-to-mobile handoff is a fast solution, but results in inefficient routes. Crossover switch based techniques provide better routes, but at the cost of call dropping during simultaneous handoff. We propose three crossover switch based techniques aimed at preventing call dropping due to disjointed connection and also improving the latency during handoff. Partial- rerouting/path-extension, which uses the features of mutual exclusion principle effectively, prevents call dropping and also invokes a route optimization phase. The route information based partial-rerouting/path-extension technique is aimed at preventing call dropping and also reducing handoff latency due to rerouting. Finally we propose a dynamic route information based technique that further reduces the handoff latency. A comparative evaluation of handoff latency and complexity of the proposed techniques with crossover switch based mobile-to-mobile handoff scheme is provided.
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