Future sensor networks will be composed of a large number of densely deployed sensors/actuators. A key feature of such networks is that their nodes are untethered and unattended. Consequently, energy efficiency is an important design consideration for these networks. Motivated by the fact that sensor network queries may often be geographical, we design and evaluate an energy efficient routing algorithm that propagates a query to the appropriate geographical region, without flooding. The proposed Geographic and Energy Aware Routing (GEAR) algorithm uses energy aware neighbor selection to route a packet towards the target region and Recursive Geographic Forwarding or Restricted Flooding algorithm to disseminate the packet inside the destination region. We evaluate the GEAR protocol using simulation. We find that, especially for non-uniform traffic distribution, GEAR exhibits noticeably longer network lifetime than non-energyaware geographic routing algorithms. 1

In recent years, several position-based routing protocols have been developed for mobile ad hoc networks. Many of these protocols assume a location service is available that provides location information on the nodes in the network. In this chapter, we survey all the proposed location information services that exist in the literature to date. We classify these location information services into three categories: proactive location database systems, proactive location dissemination systems, and reactive location systems.

Geographic routing protocols allow stateless routing in mobile ad hoc networks (MANETs) by taking advantage of the location information of mobile nodes and thus are highly scalable. A central challenge in geographic routing protocols is the design of scalable distributed location services that track mobile node locations. A number of location services have been proposed, but little is known about the relative performance of these location services. In this paper, we perform a detailed performance comparison of three rendezvous-based location services that cover a range of design choices: a quorum-based protocol (XYLS) which disseminates each node's location to O( # N) nodes, a hierarchical protocol (GLS) which disseminates each node's location to O(log N) nodes, and a geographic hashing based protocol (GHLS) which disseminates each node's location to O(1) nodes.

A predictive model-based mobility tracking method, called dead reckoning, is developed for mobile ad hoc networks. It disseminates both location and movement models of mobile nodes in the network so that every node is able to predict or track the movement of every other node with a very low overhead.

Abstract — Location-based routing significantly reduces routing overheads in mobile ad hoc networks (MANETs) by utilizing position information of mobile nodes in forwarding decisions. Location service is therefore critical to location-based routing, the scalability of which hinges largely on the overheads of such service. Although several location service schemes have been proposed, most of them focus only on one or two aspects of the scalability in their performance evaluations, and a comprehensive comparative study is missing. In this paper, we first explore the design space of location services and present a taxonomy of existing schemes. We then propose HIGH-GRADE, a new location service scheme that employs a multilevel hierarchical location server structure and a multi-grained location information organization. We develop a uniform theoretical framework to analyze HIGH-GRADE and four other existing schemes in terms of three metrics: location maintenance cost, location query cost, and storage requirement cost. We show that the design of a location service scheme involves tradeoffs among all the three kind of overheads. Further, in our theoretical analysis and simulation experiments, HIGH-GRADE demonstrates superior scalability, especially when a localized data traffic pattern is assumed. I.

A predictive model-based mobility tracking method, called dead reckoning, is proposed for mobile ad hoc networks. It disseminates both location and movement models of mobile nodes in the network so that every node is able to predict or track the movement of every other node with a very low overhead. This technique is applied to solve the unicast routing problem by modeling link costs using both link lifetime and geographic distance from the destination to the link egress point. This method presents a much superior routing performance compared to either DSR or AODV, two other popular routing protocols, particularly in terms of delivery fraction and routing load.

This paper proposes a location service to assist location-based routing protocols, realized through a novel Associativity-Based clustering protocol. The main goal of our scheme, which employs hierarchical principles, is to minimize the control traffic associated with location-management. In location-based routing protocols, the control traffic is mainly due to location-updates, queries and responses. Our scheme employs a novel geographically-oriented clustering scheme in order to minimize control traffic without impairing performance. In our location management scheme, nodes are assigned home-zones, and are required to send their location-updates to their respective homezones through a dominating-set. This strategy, unlike similar location-management approaches, minimizes inevitable superfluous flooding by every node, and prevents location updates and queries from traversing the entire network unnecessarily, hence conserving bandwidth and transmission power. The proposed scheme is evaluated through mathematical analysis and simulations, and the results indicate that our protocol scales well with increasing node-count, node-density and node-speed.

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Location services are used in mobile ad hoc and hybrid networks either to locate the geographic position of a given node in the network or for locating a data item (content). One of the main usages of position location services is in location based routing algorithms. In particular, geographic routing protocols can route messages more efficiently to their destinations based on the destination node’s geographical position, which is provided by a location service. A content location service provides to the requesting node either the requested data itself or the identifier of the node that stores this data. Sometimes the position of the node that stores the data is also provided. Such data location services are useful for implementing content-sharing applications, cooperative caching, and publish subscribe systems. In this paper we present a taxonomy of location services and survey known techniques for constructing such a service in wireless ad hoc and hybrid networks.

Location management in mobile ad hoc networks are mainly motivated by the adoption of geographic routing of packets because of scalabifity issues. The main location management proposals have, as a common characteristic, two distinct phases: the location query of the position of a destination node and the data transmission toward that node. We propose to send the initial packets of a flow to learn the position of their destination instead of adopting a dedicated query packet. Such approach can be applied to previous schemes in location management. We identify the conditions under which the proposed scheme is worth using in comparison with the traditional one having two distinct phases. An adaptive mechanism is proposed to allow a source to evaluate which scheme is most likely to reduce the overall cost of a given transmission. As our scheme is shown to specially benefit short lived flows, we expect to give a better advantage to the majority of flows. At the longterm, as each cooperative node seeks to adopt the lowest cost scheme for each transmission, we can expect an overall cost reduction of the location management as well as a reduction in the battery consumption.