We introduce and evaluate a very simple landmark-based network partition technique called Hierarchical Bipartition Routing (HBR) to support routing with delivery guarantee in wireless ad hoc sensor networks. It is a simple routing protocol that can easily be combined with any other greedy routing algorithm to obtain delivery guarantee. The efficiency of HBR increases if the network is sparse and contains obstacles. The space necessary to store the additional routing information at a node u is on average not larger than the size necessary to store the IDs of the neighbors of u. The amount of work to setup the complete data structure is on average proportional to flooding the entire network log(n) times, where n is the total number of sensor nodes. We evaluate the performance of HBR in combination with two simple energy-aware geographic greedy routing algorithms based on physical coordinates and virtual coordinates, respectively. Our simulations show that the difference between using HBR and a weighted shortest path to escape a dead-end is only a few percent in typical cases.
An alternative way for delivery guarantee can be obtained by hierarchical addressing, see for example @cite_4 . Tsuchiya solves this problem by allowing nodes to self configure their addresses. The protocol uses a hierarchical set of landmark nodes that periodically send scoped route discovery messages. A node's address is the concatenation of its closest landmark at each level in the hierarchy. The overhead of route setup can be reduced to @math and nodes only hold state for their immediate neighbors and their next hop to each landmark. However, this requires a protocol that creates and maintains this hierarchy of landmarks and appropriately tunes the landmark scopes. Recent proposals adopting this approach have been fairly complex @cite_2 in contrast to our design goal of configuration simplicity, see also @cite_23 for an overview.
@cite_4 @cite_23 @cite_2
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Today's Internet routing protocols are built upon the basic incorrect assumption that routers propagate truthful routing information. As a result, the entire Internet infrastructure is vulnerable to security attacks from routers that propagate incorrect routing information. In fact, a single router is capable of hijacking a significant fraction of routes by launching such an attack. This issue is not just restricted to Internet routing protocols but is widely prevalent in several routing protocols that have been proposed in the research literature. Many existing approaches for addressing the security problems of routing protocols typically assume the existence of a Public-Key Infrastructure (PKI) or some form of prior key distribution mechanism along with a central authority. While a PKI does enable addressing this security threat, building one such key-distribution infrastructure may not always be feasible. One faces serious deployment barriers in building an Internet-wide PKI with a central authority especially given that deploying one such architecture requires approval across political and economic boundaries. Previous efforts for securing Internet routing and the Domain Name System using a PKI have not moved towards adoption. In this dissertation, we address the following question: Using purely decentralized mechanisms (void of a PKI and a central authority), what is the best level of security achievable for a routing protocol in the presence of adversaries? One of the key conclusions that we arrive at is the direct relationship between decentralized security and the reliable communication problem. The reliable communication problem relates to determining the constraints under which a set of good nodes in a network can reliably communicate messages between themselves in the face of adversarial nodes in the network. We show theoretical results on the constraints under which the reliable communication problem is solvable. Based on these results, we describe the design of a reliable communication toolkit that implements our algorithms and provides a suite of generic security primitives that can be used to secure a variety of routing protocols. These security mechanisms supported by the toolkit are well suited for Internet routing since they are both easy to deploy as well as offer good security guarantees. We also show that the toolkit has broader applicability beyond routing protocols to: (a) achieve decentralized key distribution; (b) address the data integrity threat to the Domain Name System (DNS) in a decentralized manner. Since ad hoc and sensor networks can be composed of a very large number of devices, the scalability of network protocols is a major design concern. Furthermore, network protocols must be designed to prolong the battery lifetime of the devices. However, most existing routing techniques for ad hoc networks are known not to scale well. On the other hand, the so-called geographical routing algorithms are known to be scalable but their energy efficiency has never been extensively and comparatively studied. In a geographical routing algorithm, data packets are forwarded by a node to its neighbor based on their respective positions. The neighborhood of each node is constituted by the nodes that lie within a certain radio range. Thus, from the perspective of a node forwarding a packet, the next hop depends on the width of the neighborhood it perceives. The analytical framework proposed in this paper allows to analyze the relationship between the energy efficiency of the routing tasks and the extension of the range of the topology knowledge for each node. A wider topology knowledge may improve the energy efficiency of the routing tasks but increases the cost of topology information due to signaling packets needed to acquire this information. The problem of determining the optimal topology knowledge range for each node to make energy efficient geographical routing decisions is tackled by integer linear programming. It is shown that the problem is intrinsically localized, i.e., a limited topology knowledge is sufficient to make energy efficient forwarding decisions. The leading forwarding rules for geographical routing are compared in this framework, and the energy efficiency of each of them is studied. Moreover, a new forwarding scheme, partial topology knowledge forwarding (PTKF), is introduced, and shown to outperform other existing schemes in typical application scenarios. A probe-based distributed protocol for knowledge range adjustment (PRADA) is finally introduced that allows each node to efficiently select online its topology knowledge range. PRADA is shown to rapidly converge to a near-optimal solution. We begin by asking whether geographic routing can scale when nodes are mobile; that is, can the overhead involved in tracking node locations be accommodated within the transport capacity of large-scale mobile ad hoc networks (MANETs)? We answer this question in the affirmative by proposing an efficient position publish protocol which fits within the transport capacity and a routing protocol that operates with imperfect information of the destination's location. The routing protocol guarantees, with high probability, routes whose lengths are within a constant “stretch” factor of the shortest path from source to destination. The key idea underlying the scalability of the publish protocol is for each potential destination node to send location updates (with frequency decaying with distance) only to a subset of network nodes, structured as annular regions around it (the natural approach of updating circular regions in distance-dependent fashion does not scale). The routing protocol must then account for the fact that the source and or relay nodes may not have estimates of the destination's location (or may have stale estimates). Spatial and temporal scaling of protocol parameters are chosen so as to guarantee scalability, route reliability and route stretch. This paper considers the problem of designing power efficient routing with guaranteed delivery for sensor networks with known distances between neighbors but unknown geographic locations. We propose Hector, a hybrid energy efficient tree-based optimized routing protocol, based on two sets of virtual coordinates. One set is based on rooted tree coordinates, and the other is based on hop distances toward several landmarks. In our algorithm, the node currently holding the packet forwards it to its neighbor that optimizes ratio of power cost over distance progress with landmark coordinates, among nodes that reduce landmark coordinates and do not increase tree coordinates. If such a node does not exist then forwarding is made to the neighbor that reduces tree based distance and optimizes power cost over tree distance progress ratio. Our simulations show the superiority of our algorithm over existing alternatives while guaranteeing delivery, and only up to 30 additional power compared to centralized shortest weighted path algorithm.