Abstract
Location-based services (LBSs) have emerged as an important interest of wireless Internet service providers (WISPs) and network operators. Positioning mobile devices in the third generation (3G) of wireless communication networks (such as Universal Mobile Telecommunications System, or UMTS) is crucial to many commercial services, including location applications that utilize accurate positioning (such as handset navigation tracking and locating points of interest); public and private emergency services, calling firefighters, medical teams, and emergency roadside assistance; and future applications (such as fraud detection, location-sensitive billing, and advertising).
However, positioning techniques vary by accuracy, implementation cost, and typical application scenarios (such as indoor and outdoor). WISPs can exploit their availability in order to locate their users in heterogeneous environments by using the most suitable positioning technique in a manner transparent to the user. The recent interworking between 3G systems and the current generation of wireless networks (such as IEEE 802.11 and Bluetooth) allows WISPs to leverage wireless networks for localization purposes. Wireless hotspots in public and private places (including homes, offices, airports, shopping malls, arenas, hotels, and libraries), along with the new generation of mobile devices supporting multiple positioning technologies (such as GPS, Bluetooth, Wi-Fi, and RFID), fosters WISP development of integrated positioning systems.
Proprietary architectural solutions have been proposed, as in Faggion et al. and Autodesk.com, to provide ubiquitous location information by integrating multiple positioning methods and infrastructures. However, in order to put minimal demand on existing operator network infrastructure and safeguard customers from risk associated with new technologies, architectures, protocols, interfaces, and application environments means using open standards when designing solutions.
An open-standards-based solution would allow and encourage interoperability, enabling WISPs that adopt different positioning solutions to negotiate roaming agreements. They could then provide LBSs to their users across networks belonging to other WISPs using different standard-compliant location platforms, expanding the coverage area of their own location services and delivering benefits for themselves and their users alike.
Here, we explore the elements involved in provisioning LBSs and propose an open-standards-based two-tier architecture for inferring location information in heterogeneous wireless networks and ubiquitous personal networks (such as 3G, WLAN, and Bluetooth). This solution exploits multiple indoor and outdoor positioning methods and technologies to infer and provide location information compliant with LBS requirements, including accuracy, coverage, privacy, and security. Being designed as a user-plane architecture means location information is part of wireless user data and transported over user bearers (such as the wireless data network IP and short message service, or SMS). The architecture is based on the Open Mobile Alliance Secure User Plane Location (SUPL) using existing standards when available and enabling exchange of positioning information between mobile terminals and the network.
The two levels in the architecture provide appropriate abstractions for supporting an extensible framework that enables new positioning technologies supported by the network or by the mobile device, added without further change to the existing architecture. Increased performance scalability makes it possible to balance the load among servers at different levels.
The logical separation between communication and positioning infrastructures allows WISPs to locate a user through a network different from the one to which it is connected. This feature enables positioning and communication technologies to evolve independently, simplifying integration between them in the architecture.
