An Energy-Efficient and Robust Indoor-Outdoor Detection Method Based on Cell Identity Map

The environmental context of a mobile phone determines how it is used and how the phone can optimize operations for greater efficiency and usability. In this paper, we consider the problem of detecting if a mobile phone is located in indoor or outdoor environment. Towards this end, we present a general method employing cell identity map and using only light sensor and proximity sensor on a mobile phone. Based on the results of a great deal of testing, we find that light intensity is the most reliable feature for indoor-outdoor detection, but light intensity is not always available because the mobile phone is sometimes put in pocket or bag. In order to solve this problem, we propose a new feature, called cell identity map (CIMAP), to be used for indoor- outdoor detection in the case that light intensity is unavailable. Implementation of the indoor-outdoor detection service based on our method is lightweight because only light sensor and proximity sensor are turned on during detection. Mobile phones maintain connections to base stations to support telecommunication services all the time, thus the marginal energy consumption of collecting cellular signal information can be negligible. It is shown to outperform existing indoor-outdoor detection techniques in terms of both energy-efficiency and robustness.