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
2141544840 2126003739 2083299955 2107080471 2135378328 2135377440 2148831787 2164138581 2115930054 2104645107 2100013559 2007008132 2057467539 2106478209 2161843738 2140525529 2140531391 2024259126 2119407531 2136316858
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. We present gradient landmark-based distributed routing (GLIDER), a novel naming addressing scheme and associated routing algorithm, for a network of wireless communicating nodes. We assume that the nodes are fixed (though their geographic locations are not necessarily known), and that each node can communicate wirelessly with some of its geographic neighbors - a common scenario in sensor networks. We develop a protocol which in a preprocessing phase discovers the global topology of the sensor field and, as a byproduct, partitions the nodes into routable tiles - regions where the node placement is sufficiently dense and regular that local greedy methods can work well. Such global topology includes not just connectivity but also higher order topological features, such as the presence of holes. We address each node by the name of the tile containing it and a set of local coordinates derived from connectivity graph distances between the node and certain landmark nodes associated with its own and neighboring tiles. We use the tile adjacency graph for global route planning and the local coordinates for realizing actual inter- and intra-tile routes. We show that efficient load-balanced global routing can be implemented quite simply using such a scheme. We study wireless ad hoc networks with a large number of nodes. We first focus on a network of n immobile nodes, each with a destination node chosen in random. We develop a scheme under which, in the absence of fading, the network can provide each node with a traffic rate spl lambda sub 1 (n)=K sub 1 (nlog n) sup -1 2 . This result was first shown in J. Hightower and G. Borriello (2001) under a similar setting, however the proof presented here is shorter and uses only basic probability tools. We then proceed to show that, under a general model of fading, each node can send data to its destination with a rate spl lambda sub 2 (n)=K sub 2 n sup -1 sup 2 (log n) sup -3 2 . Next, we extend our formulation to study the effects of node mobility. We first develop a simple scheme under which each of the a mobile nodes can send data to a randomly chosen destination node with a rate spl lambda sub 3 (n)=K sub 3 n sup -1 2 (log n) sup -3 2 , and with a fixed upper bound on the packet delay d sub max that does not depend on n. We subsequently develop a scheme under which each of the nodes can send data to its destination with a rate spl lambda sub 4 (n)=K sub 4 n sup (d-1) 2 (log n) sup -5 2 provided that nodes are willing to tolerate packet delays smaller than d sub max (n)<K sub 5 n sup d , where 0<d<1. With both schemes, a general model of fading is assumed. In addition, nodes require no global topology or routing information, and only need to coordinate locally. The above results hold for an appropriate choice of values for the constants K sub i , and with probability approaching 1 as the number of nodes n approaches infinity. We present a route planning technique solely based on the concept of node contraction. The nodes are first ordered by 'importance'. A hierarchy is then generated by iteratively contracting the least important node. Contracting a node υ means replacing shortest paths going through v by shortcuts. We obtain a hierarchical query algorithm using bidirectional shortest-path search. The forward search uses only edges leading to more important nodes and the backward search uses only edges coming from more important nodes. For fastest routes in road networks, the graph remains very sparse throughout the contraction process using rather simple heuristics for ordering the nodes. We have five times lower query times than the best previous hierarchical Dijkstra-based speedup techniques and a negative space overhead, i.e., the data structure for distance computation needs less space than the input graph. CHs can be combined with many other route planning techniques, leading to improved performance for many-to-many routing, transit-node routing, goal-directed routing or mobile and dynamic scenarios. Geographic routing (GR) algorithms, require nodes to periodically transmit HELLO messages to allow neighbors know their positions (beaconing mechanism). To reduce the control overhead due to theses messages, beacon-less routing algorithms have recently been proposed. However, existing beacon-less algorithms have not considered realistic physical layers. Therefore, those algorithms can not work properly in realistic scenarios. In this paper we present a new beacon-less routing protocol called BOSS. Its design is based on the conclusions of our open-field experiments using Tmote-sky sensors. BOSS is adapted to error-prone networks and uses a new delay function to reduce collisions and duplicate messages produced during the phase of selecting the next forwarder. Through extensive simulations we compare BOSS with BLR and CBF and show that our scheme is able to achieve almost perfect packet delivery ratio (like BLR) while having a low bandwidth consumption (even lower than CBF). We study the problem of data-driven routing and navigation in a distributed sensor network over a continuous scalar field. Specifically, we address the problem of searching for the collection of sensors with readings within a specified range. This is named the iso-contour query problem. We develop a gradient based routing scheme such that from any query node, the query message follows the signal field gradient or derived quantities and successfully discovers all iso-contours of interest. Due to the existence of local maxima and minima, the guaranteed delivery requires preprocessing of the signal field and the construction of a contour tree in a distributed fashion. Our approach has the following properties: (i) the gradient routing uses only local node information and its message complexity is close to optimal, as shown by simulations; (ii) the preprocessing message complexity is linear in the number of nodes and the storage requirement for each node is a small constant. The same preprocessing also facilitates route computation between any pair of nodes where the the route lies within any user supplied range of values. Geographic routing can provide efficient routing at a fixed overhead. However, the performance of geographic routing is impacted by physical voids, and localization errors. Accordingly, virtual coordinate systems (VCS) were proposed as an alternative approach that is resilient to localization errors and that naturally routes around physical voids. However, VCS also faces virtual anomalies. Moreover, there are no effective complementary routing algorithm that can be used to traverse voids. Most existing solutions use variants of flooding or blind searching when a void is encountered. In this paper, we make the observation that increasing the number of dimensions in virtual coordinate systems cannot eliminate all virtual anomalies since some portions of the network may be 1-connected to the rest of the network. As a result, we conjecture that a delivery guaranteed protocol must be one-dimensional and propose a spanning-path virtual coordinate system that has this property. We develop a delivery guaranteed routing algorithm on top of this system that can be used on its own, or as a complementary algorithm to traverse voids. With this approach, and for the first time, we demonstrate a stateless and delivery guaranteed geometric routing algorithm on VCS. When used in conjunction with our previously proposed aligned virtual coordinate system (AVCS), it out-performs not only all geometric routing protocols on VCS, but also geographic routing with accurate location information. We propose a novel localized routing protocol for wireless sensor networks (WSN) that is energy-efficient and guarantees delivery. We prove that it is constant factor of the optimum for dense networks. To forward a packet, a node s in graph G computes the cost of the energy weighted shortest path (SP) between s and each of its neighbors which are closer to the destination than itself. It then selects node x which minimizes the ratio of the cost of the SP to the progress towards the destination. It then sends the message to the first node on the SP from s to x: say node x'. Node x' restarts the same greedy routing process until the destination is reached or the routing fails. To recover from failure, our algorithm invokes face routing that guarantees delivery. This work is the first to optimize energy consumption of face routing. First, we build a connected dominating set from graph G, second we compute its Gabriel graph to obtain the planar graph G'. Face routing is applied on G' only to decide which edges to follow in the recovery process. On each edge, greedy routing is used. This two-phase (greedy-Face) end-to-end routing process (EtE) reiterates until the final destination is reached. Simulation results show that EtE outperforms several existing geographical routing on energy consumption metric. Many message delivery services are based on publish-subscribe systems designed to distribute updates through centralized infrastructures requiring active Internet connections. For mobile devices, individual nodes should have the ability to propagate messages to interested users over ad-hoc wireless connections thereby removing the dependence on Internet and centralized servers. These nodes are sometimes stationary, but are often mobile, creating intermittent networks of nodes that tend to be socially related. In this paper, we propose LESC, a delay-tolerant message delivery protocol, which facilitates efficient message dissemination in a decentralized, ad-hoc fashion and can be implemented using a commodity mobile communication technology such as Bluetooth LE. By leveraging the frequent collocation of socially related peers, nodes strategically become information carriers with the ability to propagate messages to out of range nodes in the future. We design a discrete event simulator that utilizes actual traveling paths derived from Google Maps. The simulator emulates LESC and the epidemic routing protocol to determine if we can achieve reasonable performance. Related works have approached the problem of publish-subscribe systems on mobile devices, but to the best of our knowledge, have not shown the feasibility of a protocol that can directly be implemented over current commodity wireless technologies. We simulate the protocol in Matlab and allow nodes to have multiple publications and subscriptions simultaneously. Due to slow advance in battery technology, power remains a bottleneck to limit wide applications of mobile ad hoc and wireless sensor networks. Among all extensive studies on minimizing power consumption, neighbor discovery is one of the fundamental components focusing on communication and access. This work surveys research literature on neighbor discovery protocols (NDPs). In general, they can be roughly classified by four underlying principles: randomness, over-half occupation, rotation-resistant intersection, and coprime cycles. The Birthday protocols act as representatives of NDPs using randomness, in which a node decides to listen, transmit, or sleep with probabilities. The original idea of over-half occupation is to be active over at least half of each period, though several refinements have been proposed to decrease its high duty cycle. Methods of rotation-resistant intersection formulate the problem of discovery using combinatorial characteristics of discrete time slots, and guarantee discovery at least once per period. Moreover, neighbor discovery can also be guaranteed within a worst-case bound, as shown by methods adopting coprime cycles. In this paper, we elaborate on these ideas and present several representative protocols, respectively. In particular, we give an integrative analysis of deterministic protocols via a generic framework. A qualitative comparison incorporating multiple criteria and a quantitative evaluation on energy efficiency are also included. Finally, we point out promising research directions towards energy-efficient neighbor discovery. n source and destination pairs randomly located in a fixed area want to communicate with each other. It is well known that classical multihop architectures that decode and forward packets can deliver at most a radicn-scaling of the aggregate throughput. The performance is limited by the mutual interference between communicating nodes. We show however that a linear scaling of the capacity with n can in fact be achieved by more intelligent node cooperation and distributed MIMO communication. The key ingredient is a hierarchical and digital architecture for nodal exchange of information for realizing the cooperation. Several localized routing protocols (see Bose, P. and Morin, P., Proc. 10th Annual Int. Symp. on Algorithms and Computation ISAAC, 1999) guarantee the delivery of packets when the underlying network topology is the Delaunay triangulation of all wireless nodes. However, it is expensive to construct the Delaunay triangulation in a distributed manner. Given a set of wireless nodes, we more accurately model the network as a unit-disk graph, UDG, in which a link between two nodes exists only if the distance between them is at most the maximum transmission range. Given a graph H, a spanning subgraph G of H is a t-spanner if the length of the shortest path connecting any two points in G is no more than t times the length of the shortest path connecting the two points in H. We present a novel localized networking protocol that constructs a planar 2.5-spanner of UDG, called the localized Delaunay triangulation, as network topology. It contains all edges that are in both the UDG and the Delaunay triangulation of all wireless nodes. Our experiments show that the delivery rates of existing localized routing protocols are increased when localized Delaunay triangulation is used instead of several previously proposed topologies. The total communication cost of our networking protocol is O(n log n) bits. Moreover, the computation cost of each node u is O(d sub u log d sub u ), where d sub u is the number of 1-hop neighbors of u in UDG. Routing in large-scale mobile ad hoc networks is challenging because all the nodes are potentially moving. Geographic routing can partially alleviate this problem, as nodes can make local routing decisions based solely on the destinations' geographic coordinates. However, geographic routing still requires an efficient location service, i.e., a distributed database recording the location of every destination node. Devising efficient, scalable, and robust location services has received considerable attention in recent years. The main purpose of this paper is to show that node mobility can be exploited to disseminate destination location information without incurring any communication overhead. We achieve this by letting each node maintain a local database of the time and location of its last encounter with every other node in the network. This database is consulted by packets to obtain estimates of their destination's current location. As a packet travels towards its destination, it is able to successively refine an estimate of the destination's precise location, because node mobility has "diffused" estimates of that location. We define and analyze a very simple algorithm called EASE (Exponential Age Search) and show that in a model where Theta(n) nodes perform independent random walks on a square lattice of size n, the length of the routes computed by EASE are of the same order as the distance between the source and destination even for very large n. Therefore, without disseminating any explicit location information, the length of EASE routes are within a constant factor of routes obtained with perfect information. We discuss refinements of the EASE algorithm and evaluate it through extensive simulations. We discuss general conditions such that the mobility diffusion effect leads to efficient routes without an explicit location service. In practical settings, where these conditions may not always be met, we believe that the mobility diffusion effect can complement existing location services and enhance their robustness and scalability Routing in large-scale mobile ad hoc networks is challenging because all the nodes are potentially moving. Geographic routing can partially alleviate this problem, as nodes can make local routing decisions based solely on the destinations' geographic coordinates. However, geographic routing still requires an efficient location service, i.e., a distributed database recording the location of every destination node. Devising efficient, scalable, and robust location services has received considerable attention in recent years. The main purpose of this paper is to show that node mobility can be exploited to disseminate destination location information without incurring any communication overhead. We achieve this by letting each node maintain a local database of the time and location of its last encounter with every other node in the network. This database is consulted by packets to obtain estimates of their destination's current location. As a packet travels towards its destination, it is able to successively refine an estimate of the destination's precise location, because node mobility has "diffused" estimates of that location. We define and analyze a very simple algorithm called EASE (exponential age search) and show that in a model where N nodes perform independent random walks on a square lattice, the length of the routes computed by EASE are on the same order as the distance between the source and destination even for very large N. Therefore, without exchanging any explicit location information, the length of EASE routes are within a constant factor of routes obtained with perfect information. We discuss refinements of the EASE algorithm and evaluate it through extensive simulations. We discuss general conditions such that the mobility diffusion effect leads to efficient routes without an explicit location service. In practical settings, where these conditions may not always be met, we believe that the mobility diffusion effect can complement existing location services and enhance their robustness and scalability. In this work we present a middleware architecture for a mobile peer-to-peer content distribution system. Our architecture allows wireless content dissemination between mobile nodes without relying on infrastructure support. Contents are exchanged opportunistically when nodes are within communication range. Applications access the service of our platform through a publish subscribe interface and therefore do not have to deal with low-level opportunistic networking issues or matching and soliciting of contents. Our architecture consists of three key components. A content structure that facilitates dividing contents into logical topics and allows for efficient matching of content lookups and downloading under sporadic node connectivity. A solicitation protocol that allows nodes to solicit content meta-information in order to discover contents available at a neighboring node and to download content entries disjointedly from different nodes. An API that allows applications to access the system services through a publish subscribe interface. In this work we describe the design and implementation of our architecture. We also discuss potential applications and present evaluation results from profiling of our system. A prerequisite for a secure communication between two nodes in an ad hoc network is that the nodes share a key to bootstrap their trust relationship. In this paper, we present a scalable and distributed protocol that enables two nodes to establish a pairwise shared key on the fly, without requiring the use of any on-line key distribution center. The design of our protocol is based on a novel combination of two techniques - probabilistic key sharing and threshold secret sharing. Our protocol is scalable since every node only needs to possess a small number of keys, independent of the network size, and it is computationally efficient because it only relies on symmetric key cryptography based operations. We show that a pairwise key established between two nodes using our protocol is secure against a collusion attack by up to a certain number of compromised nodes. We also show through a set of simulations that our protocol can be parameterized to meet the desired levels of performance, security and storage for the application under consideration. This paper is meant to be an illustration of the use of stochastic geometry for analyzing the performance of routing in large wireless ad hoc (mobile or mesh) networks. In classical routing strategies used in such networks, packets are transmitted on a pre-defined route that is usually obtained by a shortest-path routing protocol. In this paper we review some recent ideas concerning a new routing technique which is opportunistic in the sense that each packet at each hop on its (specific) route from an origin to a destination takes advantage of the actual pattern of nodes that captured its recent (re)transmission in order to choose the next relay. The paper focuses both on the distributed algorithms allowing such a routing technique to work and on the evaluation of the gain in performance it brings compared to classical mechanisms. On the algorithmic side, we show that it is possible to implement this opportunistic technique in such a way that the current transmitter of a given packet does not need to know its next relay a priori, but the nodes that capture this transmission (if any) perform a self-selection procedure to choose the packet relay node and acknowledge the transmitter. We also show that this routing technique works well with various medium access protocols (such as Aloha, CSMA, TDMA). Finally, we show that the above relay self-selection procedure can be optimized in the sense that it is the node that optimizes some given utility criterion (e.g. minimize the remaining distance to the final destination), which is chosen as the relay. The performance evaluation part is based on stochastic geometry and combines simulation as analytical models. The main result is that such opportunistic schemes very significantly outperform classical routing schemes when properly optimized and provided at least a small number of nodes in the network know their geographical positions exactly.