Quality Estimation for Zone-based LBS under Realistic Positioning Systems

Location–based Services (LBS) are typically provided to users depending on their geographic location. Zone–based LBS form a subclass, that restricts the service provisioning to users within a predefined authorized zone. However, when deployed with real positioning systems, such LBS are exposed to position measurements with probably large errors compared to the size of the LBS's authorized zone. This may cause wrong authorization decisions and severe service malfunctions. Hence, a methodology to choose and rate an appropriate positioning system for such LBS in the forefront of their deployment is urgently needed. In order to solve this problem, this paper first presents three geospatial Quality of Service (QoS) metrics for LBS. A methodology to compute the expected QoS values for LBS when operated with a given positioning system is presented. This approach finally allows to determine if a given positioning system yields sufficiently high QoS values for the underlying LBS. Consequently, an appropriate positioning system can be identified and rated. Finally, the effectiveness of the approach is illustrated in a case study comprising two indoor LBS in a typical office environment.