April 3, 2017
Evolving and improving the science behind spectrum sharing is essential to NTIA’s commitment to meeting the demand for spectrum among federal and commercial users. Just as collaboration between spectrum users can unlock sharing opportunities, researchers can work together to advance spectrum efficiencies and mitigate interference.
ITS has taken a major step toward better collaboration by publishing a reference implementation of the Extended-Hata Urban Propagation Model (eHata) in the NTIA/ITS GitHub at https://github.com/NTIA/ehata. ITS created eHata to predict propagation of new commercial broadband services in the 3.5 GHz band. An analysis of those predictions enabled regulators to significantly expand commercial access to the 3.5 GHz band through the establishment of the Citizens Broadband Radio Service (CBRS). The analysis was presented in Technical Report TR-15-517: 3.5 GHz Exclusion Zone Analyses and Methodology. The analysis was based on propagation predictions performed by extending the Hata model, a radio propagation model for outdoor cellular transmissions at 150-1500 MHz that considers the effects of diffraction, reflection, and scattering caused by city structures. To predict propagation of new commercial broadband services in the 3.5 GHz band, NTIA engineers extended the Hata model in both frequency and distance, creating the Extended-Hata Urban Propagation Model (eHata).
The Hata propagation model considers the effects of diffraction, reflection, and scattering caused by city structures for outdoor cellular transmissions at 150-1500 MHz. NTIA engineers created eHata by extending the Hata model in both frequency and distance. By providing an open source implementation that is freely available for use and re-use, ITS hopes to advance development of widely accepted propagation models. Rather than duplicating efforts with competing versions of eHata, researchers can focus on enhancing and improving the open source implementation.
The Wireless Innovation Forum’s Spectrum Sharing Committee, which is developing the technical standards for the Spectrum Access System (SAS) that will enable commercial operations in the 3.5 GHz band, has proposed using eHata to calculate coverage and protection areas. WInnForum can now use or adapt the ITS source code for propagation prediction and focus their efforts on developing other aspects of the SAS functional architecture. The code can also allow other organizations and researchers that are interested in urban propagation modeling to engage with ITS to explore how best to model urban environments.
Whereas papers and reports disseminate knowledge unidirectionally, open source code repositories allow for two-way collaboration between ITS and the research community. ITS plans to continue to release open source reference implementations 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 other federal agencies as well as industry to leverage 100 years of ITS research expertise to address current and future spectrum issues.