Localization is a fundamental operation in mobile and self-configuring networks such as sensor networks and mobile ad hoc networks. For example, sensor location is often critical for data interpretation; moreover, network protocols, such as geographic routing and geographic storage require individual sensors to know their coordinates. Existing research focuses on localization mechanisms: algorithms and infrastructure designed to allow the sensors to determine their location. In a mobile environment, a related problem exists: when nodes are mobile, the underlying localization mechanism must be invoked repeatedly to maintain accurate location information. We propose and investigate adaptive and predictive protocols that control the frequency of localization based on sensor mobility behavior to reduce the energy requirements for localization while bounding the localization error. In addition, we evaluate the energyaccuracy tradeoffs that arise: intuitively, higher the frequency of localization, the lower the error introduced because of mobiliy. However, localization is a costly operation since it involves both communication and computation. Since energy is at a premium in wireless devices, it is important to perform localization in an energy efficient fashion. Our results indicate that the proposed protocols reduce the localization energy significantly without sacrificing accuracy.

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Routing in multi-

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