We consider routing problems in ad hoc wireless networks modeled as unit graphs in which nodes are points in the plane and two nodes can communicate if the distance between them is less than some fixed unit. We describe the first distributed algorithms for routing that do not require duplication of packets or memory at the nodes and yet guarantee that a packet is delivered to its destination. These algorithms can be extended to yield algorithms for broadcasting and geocasting that do not require packet duplication. A byproduct of our results is a simple distributed protocol for extracting a planar subgraph of a unit graph. We also present simulation results on the performance of our algorithms.

In this paper we study local routing algorithms on geometric networks. Formally speaking, suppose that we want to travel from a vertex s to a vertex t of a geometric network. A routing algorithm is called a local routing algorithm if it satisfies the following conditions:

We consider online routing strategies for routing between the vertices of embedded planar straight line graphs. Our results include (1) two deterministic memoryless routing strategies, one that works for all Delaunay triangulations and the other that works for all regular triangulations, (2) a randomized memoryless strategy that works for all triangulations, (3) an O(1) memory strategy that works for all convex subdivisions, (4) an O(1) memory strategy that approximates the shortest path in Delaunay triangulations, and (5) theoretical and experimental results on the competitiveness of these strategies.

AbstractÐIn a localized routing algorithm, each node makes forwarding decisions solely based on the position of itself, its neighbors, and its destination. In distance, progress, and direction-based approaches (reported in the literature), when node A wants to send or forward message m to destination node D, it forwards m to its neighbor C which is closest to D (has best progress toward D, whose direction is closest to the direction of D, respectively) among all neighbors of A. The same procedure is repeated until D, if possible, is eventually reached. The algorithms are referred to as GEDIR, MFR, and DIR when a common failure criterion is introduced: The algorithm stops if the best choice for the current node is the node from which the message came. We propose 2-hop GEDIR, DIR, and MFR methods in which node A selects the best candidate node C among its 1-hop and 2-hop neighbors according to the corresponding criterion and forwards m to its best 1-hop neighbor among joint neighbors of A and C. We then propose flooding GEDIR and MFR and hybrid single-path/flooding GEDIR and MFR methods which are the first localized algorithms (other than full flooding) to guarantee the message delivery (in a collision-free environment). We show that the directional routing methods are not loopfree, while the GEDIR and MFR-based methods are inherently loop free. The simulation experiments, with static random graphs, show that GEDIR and MFR have similar success rates, which is low for low degree graphs and high for high degree ones. When successful, their hop counts are near the performance of the shortest path algorithm. Hybrid single-path/flooding GEDIR and MFR methods have low communication overheads. The results are also confirmed by experiments with moving nodes and MAC layer. Index TermsÐRouting, wireless networks, distributed algorithms, shortest path, broadcasting 1

Recent availability of small inexpensive low power GPS receivers and techniques for finding relative coordinates based on signal strengths, and the need for the design of power efficient and scalable networks, provided justification for applying position based routing methods in ad hoc networks. A number of such algorithms were developed in last few years, in addition to few basic methods proposed about fifteen years ago. This article surveys known routing methods, and provides their taxonomy in terms of a number of characteristics: loop-free behavior, distributed operation (localized, global or zonal), path strategy (single path, multi-path or flooding based), metrics used (hop count, power or cost), memorization (memoryless or memorizing past traffic), guaranteed delivery, scalability, and robustness (strategies to handle the position deviation due to the dynamicity of the network). We also briefly discuss relevant issues such as physical requirements, experimental design, location updates, QoS, congestion, scheduling node activity, topology construction, broadcasting and network capacity.

In this paper we propose several new clustering algorithms for nodes in a mobile ad hoc network. We propose to combine two known approaches into a single clustering algorithm which considers connectivity as a primary and lower ID as secondary criteria for selecting clusterheads. Several inherently collision-free clustering algorithms are then designed based on a depth first search (DFS) traversal of nodes in the network. These algorithms are initialized by any node and are fully distributed. They create and maintain k-clusters, in which any node is at distance at most k hops from the clusterhead. In the clustering process, each node is either a clusterhead, a covered or undecided node. In the basic k-cluster algorithm, each undecided visited node in DFS declares itself a clusterhead and covers all its k-hop neighbors. In the highest connectivity k-cluster algorithms, each undecided visited node checks all its undecided k-hop neighbors and chooses one with the largest connectivity to be...

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Recently, several fully distributed (localized) location-based routing protocols for a mobile ad hoc network were reported in literature. They are variations of directional (DIR), geographic distance (GEDIR) or progress-based (MFR) routing methods. In DIR methods each node A (the source or intermediate node) transmits a message m to several neighbors whose direction is closest to the direction of D. In MFR (most forward progress within radius), and GEDIR (GEographic DIstance Routing) methods, when node A wants to send m to node D, it forwards m neighbor C whose protection or distance (respectively) is closest to D among all neighbors of A. The same procedure is repeated until D, if possible, is eventually reached. In this paper, we introduce three variants of multiple path c-GEDIR, c-DIR and c-MFR methods in which mis initially sent to c best neighbors according to corresqj7fixE criterion, andafterwards on intermediatenodes itis forwarded to only the bes neighbor. In the original c-path method, only thefirs received copy at intermediatenodes is forwarded to the bes neighbor. In the alternate c-path method, the ith received copyis forwarded to ithbes neighbor, according to these jEUEx criterion. In the disjoint c-path method, each intermediate node, upon receiving themesGfiU/ will forward it toits bes neighbor among thos who never received themesxflE (thus in effect, the methods attempts c disoint pathsT The sjExQExj7 experiments with random graphs sap that disjoint multiple path methods provide high sghjGE rates and sdjG hopcounts forsrjE values of c: They als have reduced flooding rates compared to the bes exis/qT multiple-pathmethods and/or methods that require memorizing pas traffic,saf as recently proposy LAR2, fGEDIR, and DFSbasG routing, and can snjE as abasq for scalable QoS routing in wireless networks.

Location discovery is a fundamental problem in wireless ad hoc networks. Most of the ad hoc routing protocols use some form of flooding to discover the location and route of a mobile node. Despite various optimizations, many messages are propagated unnecessarily. We propose the Optimal Flooding Protocol (OFP), based on a variation of The Covering Problem that is encountered in geometry, to minimize the unnecessary transmissions drastically and still be able to cover the whole region. OFP out-performs other existing variations of flooding. This simple protocol uses up to 65 % to 80% fewer messages than flooding and 50% fewer messages than gossip-based flooding, which has been proposed as one of the best optimized variation of flooding. OFP is scalable with respect to number of nodes; in fact OFP's performance improves with the number of nodes.

Abstract — Geometric routing using source–destination locations has been suggested as a scalable alternative to conventional routing approaches in mobile ad hoc networks. Prior studies have shown that the location of a destination can be found efficiently in large/dense ad hoc networks using intelligent location management schemes by recruiting nodes in specific unit regions of the terrain as location servers. In this work, we show that certain location management protocols that use a grid based approach suffer from the empty server region problem and that their performance can be seriously degraded with decreasing node density in sparse or irregular ad hoc networks. In order to tackle this problem, we introduce proxy based location management, a novel enhancement that can be used in conjunction with existing location management protocols to operate efficiently in sparse or irregular ad hoc networks. Extensive simulations show that proxy based location management combined with routing on an overlay graph constructed from the unit regions operates more effectively in sparse networks than SLURP/GPSR, an existing location management scheme and a geometric routing protocol that routes packets on a planar graph extracted from the unit disk graph.