Introduction

Abstract

The proliferation of wireless and mobile devices has fostered the demand for context-aware applications, in which location is viewed as one of the most significant contexts. For example, pervasive medical care is designed to accurately record and manage patient movements [1, 2]; smart space enables the interaction between physical space and human activities [3, 4]; modern logistics has major concerns on goods transportation, inventory, and warehousing [5, 6]; environmental monitoring networks sense air, water, and soil quality and detect the source of pollutants in real time [7–13]; and mobile peer-to-peer computing encourages content sharing and contributing among mobile hosts in the vicinity [14, 15]. A detailed survey on location-based applications can be found in [16, 17].