Indoor Communication over TV Gray Spaces based on Spectrum Measurements Luca Bedogni, Marco Di Felice, Fabio Malabocchia, Luciano Bononi Department of Computer Science and Engineering, University of Bologna Telecom Italia Spa Email: {lbedogni,difelice,bononi}@cs.unibo.it Email: fabio.malabocchia@telecomitalia.it June 3, 2014 Abstract The spectrum scarcity is a known problem for a multitude of ser- vices. Several bands have been licensed, and nowadays it is difficult to find unused spectrum. Cognitive radio networks have been proposed as a possible solution to contrast the experienced spectrum scarcity. One case of particular interest come from the scarce utilization of TV fre- quencies, which form the so-called TV White Spaces. In this paper we investigate the utilization of occupied frequencies by secondary devices for indoor communication. We conduct spectrum measurements to quantify the availability of spectrum, and study how indoor communications could impact the DTV receiver. We show that this portions of spectrum, called gray spaces, can be utilized under certain circumstances, for example in highly populated areas, which is the scenario in which it is harder to find TV White Spaces. Simulation studies show the impact gray spaces can have on the available spectrum for opportunistic use. 1 Introduction Nowadays, most of the frequency spectrum is allocated or licentiated, in a static way, to serve various services. Cellular communications, Digital TV, Medical wireless networks are only few examples of the vastity of services that rely on wireless communications. This huge trend is envisioned to become even larger, with 50 billions of devices seamlessy connected to the internet by 2020 [9]. This huge demand of spectrum frequencies and bandwidth contrast with the fact that unused bands are rare nowadays, since most of the existing frequencies have been already allocated to different services. Additional bandwidth is needed by cellu- lar communications, which already present some periods of downtime when huge traffic demand is experienced, for instance during sport events or music concerts [18]. In addition, with the Internet of Things paradigm that is growing fast and starts to be deployed to cover everyday needs, Machine-to-Machine communi- cations is envisioned to become one huge bandwidth suitor [2] [4]. Moreover, 1