Performance Comparison between GSM and Wi-Fi Localization in both Indoor and Outdoor Environments

Location is considered as one of most widely utilized context information in context-aware computing. Location-aware services leverage the location of people and objects to provide relevant or personalized information and services to users. An enabling tech-nology is a ubiquitous (pervasive) location system that can accurately track positions of people and objects anytime anywhere in both indoor and outdoor environments. Exam-ples of these location-aware services include navigation services, location-based advertisement services, logistical services, inventory control services, museum guide services, etc.
To evaluate feasibility of constructing a practical localization system, which can have wide coverage in both the indoor and outdoor environments, we have selected GSM and Wi-Fi based localization systems, implemented them on commercial GSM/Wi-Fi smart phones and PDAs, and compared their performance under different positioning algo-rithms (e.g., centroid, weighted centroid, and fingerprinting) and different indoor/outdoor environments (e.g., offices, urban and rural areas). Results have shown that the average positional accuracy of a GSM based localization in indoor(outdoor) en-vironment is 11(113) meters, and the average positional accuracy of a Wi-Fi based localization system in indoor(outdoor) environment is 5(29) meters. We consider the accuracy feasible and sufficient for an indoor/outdoor localization system. From our deployment experiences, we discuss several practical problems encountered and com-pare the pros and cons of each localization method. Finally, we propose a GSM/Wi-Fi hybrid localization system that combines the advantages of both GSM/Wi-Fi localiza-tion systems.