Aggregate interference in ISM band: WBANs need cognitivity?

Estimating the aggregate interference is required in order to predict the performance of a wireless system in its working environment. Body Area Networks (BANs) for healthcare applications are becoming a reality, allowing patients to be monitored continuously without forcing them to stay in bed or in hospital. The increasing number of wireless medical devices makes the ISM (Industrial, Scientific and Medical) band particularly crowded. If new smart BANs have to correctly operate in hospital, coexistence with the existing wireless devices must be accurately investigated, starting with studying the interference in the operating frequency band. In this paper we propose an interference model based on real measurements carried out in the emergency ward of a modern city hospital, as well as in home and office environments, which are the three main locations where a patient monitored by a WBAN spends the most of the time. The measurements are used to model the probability density function of the aggregate interference as well as the occupancy of the channel.