Impact of human crowd activity on indoor wireless channels - Assessment and modeling

Indoor localization is one key element in current and future mobile applications and services. Based on the estimate of ranges between the mobile user and anchors, like base stations or access points, and between mobile users in the cooperative context, geolocation algorithms must be robust in crowded and multipath-rich indoor environments. Channel models play a fundamental role in the validation and assessment of the algorithm performance. They are required to reproduce realistic propagation characteristics. However, state of the art channel models do not deterministically consider the time-variant nature of an indoor environment populated with humans. This paper presents indoor measurements that have been conducted to evaluate the influence of human crowd activity on the time-variant channel and the round-trip delay ranging link performance. Measurements were used as well to validate a time-variant indoor ray-based model, which aims at feeding the design and assessment of indoor wireless communication based geolocation algorithms with realistic non-stationary channels.