We consider routing security in wireless sensor networks. Many sensor network routing protocols have been proposed, but none of them have been designed with security as agq1( We propose securitygcur forrouting in sensor networks, show how attacks agacks ad-hoc and peer-to-peer networks can be adapted into powerful attacks agacks sensor networks, introduce two classes of novel attacks agacks sensor networks----sinkholes and HELLO floods, and analyze the security of all the major sensor networkrouting protocols. We describe crippling attacks against all of them and sug@(5 countermeasures anddesig considerations. This is the first such analysis of secure routing in sensor networks.

Although far from optimal, flooding is an indispensable message dissemination technique for network-wide broadcast within mobile ad hoc networks (MANETs). As such, the plain flooding algorithm provokes a high number of unnecessary packet rebroadcasts, causing contention, packet collisions and ultimately wasting precious limited bandwidth. Studies have been undertaken to optimize flooding using a deterministic approach. Because of the highly dynamic and mobile characteristics of MANETs, probabilistic algorithms may be better suited. We explore the phase transition phenomenon observed in percolation theory and random graphs as a basis for defining probabilistic flooding algorithms. We consider models with and without packet collisions to better understand when phase transition occurs. We show through simulation that in cases of no collision control, probabilistic flooding greatly enhances network performance while significantly reducing broadcast packets in dense networks, although phase transition is not observed.

We propose FResher Encounter SearcH (FRESH), a simple algorithm for efficient route discovery in mobile ad hoc networks. Nodes keep a record of their most recent encounter times with all other nodes. Instead of searching for the destination, the source node searches for any intermediate node that encountered the destination more recently than did the source node itself. The intermediate node then searches for a node that encountered the destination yet more recently, and the procedure iterates until the destination is reached. Therefore, FRESH replaces the single network-wide search of current proposals with a succession of smaller searches, resulting in a cheaper route discovery. Routes obtained are loop-free. The performance of such...

Dissemination of common information through broadcasting is an integral part of wireless network operations such as query of interested events, resource discovery and code update. In this paper, we characterize the behavior of information dissemination in power-constrained wireless networks by defining two quantities, i.e., broadcast capacity and information diffusion rate and derive fundamental limits in both random extended and dense networks. We find that using multihop relay, the rate of broadcasting continuous stream is Θ(log(n) − α 2) in extended networks; while direct single-hop broadcast is efficient for dense networks. Furthermore, regardless of the density, information can diffuse at constant speed, i.e., Θ(1) in both extended and dense networks. The theoretical bounds obtained and proof techniques are instrumental to the modeling and design of efficient wireless network protocols.

Large-scale dense sensor networks require mechanisms to extract topology information that can be used for various aspects of sensor network management. It is critical for any topology discovery algorithm in dense networks not only to adhere to the resource constraints of bandwidth and energy but also to provide several views of the network. Due to factors of density, redundancy and failures it may not be possible or practical to get a complete view of the topology. In this paper, we describe a distributed parameterized algorithm for Sensor Topology Retrieval at Multiple Resolutions (STREAM), which makes a tradeoff between topology details and resources expended. The algorithm retrieves network state at multiple resolutions at a proportionate communication cost. We also define various classes of topology queries and show how the parameters in the algorithm can be used to support queries specific to sensor networks. We show that topology determined at different resolutions is sufficient for approximating different network properties. We also show that STREAM can be used for general-purpose multi-resolution information retrieval in sensor networks.

Abstract. This paper describes formal probabilistic models of flooding and gossiping protocols, and explores the influence of different modelling choices and assumptions on the results of performance analysis. We use Prism, a model checker for probabilistic systems, for the formal analysis of protocols and small network topologies, and use in addition Monte-Carlo simulation, implemented in Matlab, to establish if the results and effects found during formal analysis extend to larger networks. This combination of approaches has several advantages. The formal model has well defined synchronization primitives with clear semantics for modelling synchronous and asynchronous communication between nodes. Model checking of the probabilistic model determines exact probabilities and performance bounds, results that cannot be obtained by simulation, and even if the model is non-deterministic. The Monte-Carlo simulation can then be used to study effects that only emerge in larger networks, such as phase transition. 1

this paper to reliable multicast and data aggregation. Data aggregation can be used to calculate global aggregates across sensor nodes (e.g., average, variance, or maximum, of a measured quantity such as temperature), for collaborative signal processing [1], etc. A multicast protocol can be used to disseminate commands or data into the sensor network

Vehicular ad hoc networks have recently been proposed as an effective tool for improving both road safety and the comfort experienced while driving. Vehicles may propagate information about potentially dangerous events such as lane changes or sudden slowdowns to vehicles in their vicinity. Moreover they can inform vehicles approaching from farther areas about accidents and possible traffic jams. In both cases, data must be routed to specific areas, along paths determined by the underlying road traffic conditions. In this paper we propose a novel approach to address this routing problem. First, we define a message propagation function that encodes information about both target areas and preferred routes. Second, we show how this function can be exploited in several routing protocols; and finally, we evaluate the effectiveness of our approach by means of simulation. Results highlight the good performance of our routing approach in sparse as well as in dense networks.

This work analyzes the connectivity of large diameter networks where every link has an independent probability p of failure. We give a (relatively simple) topological condition that guarantees good connectivity between regions of such a network. Good connectivity means that the regions are connected by nearly as many disjoint, fault-free paths as there are when the entire network is fault-free. The topological condition is satisfied in many cases of practical interest, even when two regions are at a distance much larger than the expected ”distance between faults”, 1/p. We extend this result to networks with failures on nodes, as well as geometric radio networks with random distribution of nodes in a deployment area of a given topography. A rigorous formalization of the intuitive notion of “hole” in a (not necessarily planar) graph is at the heart of our result and our proof. Holes, in the presence of faults, degrade connectivity in the region “around ” them to a distance that grows with the size of the hole and the density of faults. Thus, to guarantee good connectivity between two regions even in the presence of faults, the intervening network should not only sport multiple paths, but also not too many large holes. Our result essentially characterizes networks where connectivity depends on the ”big picture ” structure of the network, and not on the local ”noise ” caused by faulty or imprecisely positioned nodes and links.

Abstract — In existing query-based routing protocols in wireless sensor networks (WSNs), a node either keeps precise route information to desired events, such as in event flooding, or does not keep any route to desired events such as in query flooding. In this paper, we propose a routing protocol, called Hint-based Routing by Scope Decay Bloom Filter (HR-SDBF), that employs probabilistic hints. In HR-SDBF, each node maintains some probabilistic hints about events and utilizes these hints to route queries intelligently. We also put forward a data structure, Scope Decay Bloom Filter (SDBF) to encode the probabilistic hints. With SDBF, the amount of information about an event is propagated, without any loss, within the k-hop neighborhood of an event source but decreases outside the k-hop neighborhood as the distance from the event source increases. Compared to existing query-based protocols, HR-SDBF greatly reduces the amortized network traffic without compromising the query success rate and achieves a higher energy efficiency. To the best of our knowledge, this is the first query routing protocol in WSNs that utilizes probabilistic hints encoded in a variant of the bloom filter. Both the analytic and the experimental results support the performance improvement of our protocol.