Evolving and improving the science behind spectrum sharing is essential to NTIA’s commitment to delivering the spectrum needed to support innovation, power next-generation technologies and ensure that federal agencies can execute their spectrum-dependent missions.
Understanding the characteristics of radio waves, especially how far they propagate and how they interact with structures and the environment, is important in planning and operating wireless systems. Any agreement to share spectrum bands will require reliable predictions of how that spectrum will perform in the real world.
The Institute for Telecommunication Sciences (ITS) recently took a major step toward a more collaborative approach to research in this area by publicly releasing an advanced software model for radio wave propagation in urban environments. This software can be used by consumers, engineers, scientists and others to explore the behavior of radio waves interacting with buildings, trees, and other environmental features.
ITS released the software to the public by publishing source code on GitHub, an online platform for open-source code. Posting to GitHub will allow researchers to use and modify the code as they wish, as well as collaborate with other researchers and avoid duplicating efforts. ITS hopes that making its source code freely available can advance development of widely accepted propagation models.
The source code posted by ITS is a “reference implementation” of the Extended-Hata Urban Propagation Model (eHata), which was created to predict propagation of new commercial broadband services proposed to share the 3.5 GHz band with Navy radars. Those predictions enabled regulators to significantly expand commercial access to the 3.5 GHz band through the establishment of the Citizens Broadband Radio Service.
The original Hata propagation model considered the effects of city structures on outdoor cellular transmissions for a limited range of parameters. NTIA engineers created eHata by extending the Hata model in both frequency and distance.
The Wireless Innovation Forum’s (WInnForum) Spectrum Sharing Committee, which is developing technical standards for commercial operations in the 3.5 GHz band, has proposed using eHata to calculate coverage areas and areas where coordination with radar systems is required. WInnForum can now use or adapt the ITS source code for propagation prediction and focus its efforts on developing other aspects of 3.5 GHz spectrum sharing. Other organizations and researchers that are interested in urban propagation modeling can also engage with ITS to explore how best to model urban environments.
ITS plans to continue to release software as it adds to the body of basic research on radio propagation modeling. These releases transfer the results of federally funded research and technology development to other researchers in this area, allowing industry and other federal agencies to leverage 100 years of ITS propagation expertise to address current and future spectrum issues.