Long-term spectral occupancy findings in Chicago

This paper summarizes some of the results of measurements and related analysis efforts at the Illinois Institute of Technology (IIT) Spectrum Observatory in Chicago over the past three years. The results are unique in the sense that the spectral occupancy estimates are based on multiple years of observations, whereas previous studies produced occupancy numbers based on short term snapshot measurements, often of a few hours duration or at most spanning a few days or weeks. The measurements are also presented in a novel way: the occupancy data in a band of interest during a one year span is graphed as a 2-dimensional image that visually reveals daily, weekly, and yearly trends and anomalies. The main objective of this paper is to present year by year first-order statistics about the spectral occupancy across multiple bands, but more details are presented about radio usage in a few bands like the TV band. In particular, we examine the spectral opportunities that are seen in the newly available “TV White Space”. The results illustrate occupancy trends and notable spectral events, such as the 2009 broadcast television transition and the related vacating of the 700 MHz band, which have created significant spectrum opportunities in the 30-1000 MHz region. The trends reported are applicable to long term spectrum modeling, spectrum planning, and regulatory decision-making efforts applicable to dynamic spectrum access networks.