Detection of Social Interaction Using Mobile Phones via Device Free Passive Localisation

Mobile devices which make use of 802.11 Wi-Fi are ubiquitous in modern society. At the same time, there is an unmet need in research and monitoring applications, and particularly in those relating to service and healthcare scenarios, to accurately detect the occurrence and hence frequency and duration of human interaction between subjects. Various sensor modalities exist that are able to perform localization of human subjects with useful degrees of accuracy, but in all cases they are either expensive, inflexible, or prone to influencing subject behaviour via the Hawthorne or observer effect. Given the ubiquity of mobile devices, it is the contention of this paper that a system which localizes human presence based on the human body's obstructive effects on RF transmissions through interpretation of perturbation of the Received Signal Strength values generated during transmission, may offer a system that is both inexpensive and flexible, while avoiding the need for direct subject participation, and thus reducing the impact of the Hawthorne effect.