## 1 Introduction
Additionally, they are expected to provide insights for establishing operational limits to make the effective implementation of TVWS networks viable in Brazil. Accordingly, this study investigates the impact of power limitation on TVWS system coverage, based on field tests conducted with the Remote Area Access Network for the Fifth Generation (5G-RANGE) system, and evaluates the necessary regulatory adjustments to ensure the viability of this technology without compromising DTV reception. This study includes laboratory experiments related to the evaluation of the coexistence of TVWS signals with the DTV system adopted in Brazil. The DTV standard employed in the tests was integrated services digital broadcasting-terrestrial (ISDB-T) [40], coexisting with other signals such as fourth-generation (4G) cellular mobile networks and 5G, as well as the 5G-RANGE system [41; 42; 43; 44], specifically developed for operation in the TVWS spectrum. From the laboratory experiments, the protection ratio (PR) values between the DTV signal and interfering signals were identified, ensuring no perceptible errors in the reception and demodulation of the DTV signal. These results are fundamental for establishing technical parameters that can be used in TVWS regulation in Brazil. Additionally, field tests were conducted considering short and long distances, aiming to complement the evaluation of the impact of Resolution No. 747 of the Anatel [33], on the performance of this type of system and to confirm the results obtained in laboratory tests. Lastly, tests considering long distances assessed the range and throughput expected from the 5G-RANGE system when operating with 1 Watt of total peak power (Wp) delivered to the antennas, which refers to the power currently imposed on TVWS services. Long-distance tests were conducted considering Line-Of-Sight (LOS) communication to highlight the impact of transmit power limitation on maximum system coverage. This scenario enables a clearer understanding of the impact of power limitation without involving additional variables present in Non-Line-Of-Sight (NLOS) communication. The long-distance tests were conducted in a rural environment because this is the key environment considered for 5G-RANGE system conception and is the scenario considered in previous reference field tests [45]. The results obtained in this study provide concrete evidence of the challenges and opportunities of implementing TVWS in Brazil. The tests demonstrate that, while the power limitation imposed by current regulations significantly restricts the coverage of the technology, adjustments such as relaxing this restriction could enable its adoption without compromising DTV reception. Moreover, the technical analysis based on experimental measurements allows for the proposal of technical parameters that can be adopted to improve regulations and make TVWS implementation more efficient and accessible. This paper is systematized as follows: Section 2 presents the conception, execution, and results of laboratory tests, defining the PRs to be observed. Section 3 outlines the methodology used for the execution and analysis of each field test related to the coexistence tests between DTV and TVWS. Section 4 showcases the results obtained in tests evaluating the impact of power restriction on the range and throughput in the 5G-RANGE system. Finally, Section 5 describes the main conclusions of this paper.