Abstract — The topology of wireless multihop ad hoc networks can be controlled by varying the transmission power of each node. We propose a simple distributed algorithm where each node makes local decisions about its transmission power and these local decisions collectively guarantee global connectivity. Specifically, based on the directional information, a node grows it transmission power until it finds a neighbor node in every direction. The resulting network topology increases network lifetime by reducing transmission power and reduces traffic interference by having low node degrees. Moreover, we show that the routes in the multihop network are efficient in power consumption. We give an approximation scheme in which the power consumption of each route can be made arbitrarily close to the optimal by carefully choosing the parameters. Simulation results demonstrate significant performance improvements. I.

Abstract—Many ad hoc routing protocols are based on some variant of flooding. Despite various optimizations, many routing messa ges are propagated unnecessarily. We propose a gossiping-based approa ch, where each node forwards a message with some probability, to reduce the ov erhead of the routing protocols. Gossiping exhibits bimodal behavio r in sufficiently large networks: in some executions, the gossip dies out quic kly and hardly any node gets the message; in the remaining executions, a sub stantial fraction of the nodes gets the message. The fraction of execution s in which most nodes get the message depends on the gossiping probability a nd the topology of the network. In the networks we have considered, using g ossiping probability between 0.6 and 0.8 suffices to ensure that almost every node gets the message in almost every execution. For large networ ks, this simple gossiping protocol uses up to 35 % fewer messages than flood ing, with improved performance. Gossiping can also be combined with va rious optimizations of flooding to yield further benefits. Simulations show that adding gossiping to AODV results in significant performance improv ement, even in networks as small as 150 nodes. We expect that the improvemen t should be even more significant in larger networks. I.

In this paper, we present a middleware architecture for coordination services in sensor networks that facilitates interaction between groups of sensors which monitor different environmental events. It sits on top of the native routing infrastructure and exports the abstraction of mobile communication endpoints maintained at the locations of such events. A single logical destination is created and maintained for every environmental event of interest. Such destinations are uniquely labeled and can be used for communication by application-level algorithms for coordination and sensory data management between the different event locales. For example, they may facilitate coordination, in a distributed intrusion scenario, among nodes in the vicinity of the intruders.

Abstract — In this paper we consider the problem of constructing a coordinate system in a sensor network where location information is not available. To this purpose we introduce the Virtual Coordinate assignment protocol (VCap) which defines a virtual coordinate system based on hop distances. As compared to other approaches, VCap is simple and have very little requirements in terms of communication and memory overheads. We compare by simulations the performances of greedy routing using our virtual coordinate system with the one using the physical coordinates. Results show that the virtual coordinate system can be used to efficently support geographic routing. Index Terms — Wireless sensor network, virtual coordinates, hop based greedy routing, performance analysis, simulations I.

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.

This article presents a class of routing protocols called RBVT, Road-Based using Vehicular Traffic information

Abstract. Developments in wireless, mobile communications combined with advancements in electronics have contributed to the emergence of a new class of networks: Wireless ad-hoc sensor networks. Tiny, smart, network-enabled sensing nodes can be deployed to construct sensor fields that form the infrastructure for various self-adaptive and autonomic applications. In this paper we identify the requirements and properties that still need to be addressed and discuss possible approaches that could be adopted in the design of efficient routing protocols for such networks. 1.

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.

The topology of a wireless multi-hop network can be controlled by varying the transmission power at each node. In general, it is not energy efficient to use the communication network where every node transmits with maximum power. For energy efficient operations, it is desirable to have a subnetwork that preserves a minimum-energy path between every pair of nodes (where a minimum-energy path is one that allows messages to be transmitted with a minimum use of energy). In this paper, we first identify conditions that are necessary and sufficient for a subnetwork of to preserve this property. Using this characterization, we then propose an efficient topologycontrol algorithm that, given a communication network, computes a subnetwork that it preserves at least one minimumenergy path between every pair of nodes. We also propose an energy-efficient reconfiguration protocol that maintains this minimum-energy path property as the network topology changes dynamically. We demonstrate the performance improvements of our algorithm over other existing topology-control algorithms through simulation.

In this article we study the data dissemination problem in which data items are flooded to all the moving objects in a mobile ad hoc network by peer-to-peer transfer. We show that if memory and bandwidth are bounded at moving objects, then the problem of determining whether a set of data items can be disseminated to all the moving objects is NP-complete. For a heuristic solution we postulate that a moving object should save and transmit the data items that are most likely to be new (i.e., previously unknown) to future encountered moving objects. We propose a method to be used by each moving object to prioritize data items based on their probabilities of being new to future receivers. The method employs a machine learning system for estimation of the novelty probability and the machine learning system is progressively trained by received data items. Through simulations based on real mobility traces, we show the superiority of the method against some natural alternatives.