## 1 Introduction
Additionally, other parameters like out-of-band emission (OOBE) attenuation, maximum effective isotropic radiated power (EIRP), power spectral density (PSD) restrictions, and maximum height above average terrain (HAAT) for antennas, which is defined as the height at which the transmission point is above the surrounding topography, are crucial considerations in deploying TVWS services. It is worth noting that while global standardization is desired, these factors may vary according to the country and its regulatory agencies [15; 19; 20]. The challenges in implementing TVWS, based on the literature, are significant, especially regarding spectrum availability, interference mitigation, and regulatory constraints. One of the main challenges is the accurate identification of available spectrum, as signal attenuation in indoor environments can make it difficult to detect TV white spaces, requiring advanced techniques such as sensing algorithms and geolocation databases. Another critical challenge is mitigating interference with primary services, such as digital television (DTV), particularly due to signal leakage in adjacent channels. Additionally, the spatial and temporal variation of the spectrum poses a problem, as the availability of TVWS channels can change dynamically over time and geographic location. International experience also highlights that spectral fragmentation is an obstacle, as available white spaces are not continuous, requiring flexible radios capable of operating with variable bandwidths. Moreover, the planning of real-world TVWS networks involves additional challenges, such as terrain modeling and adapting equipment to local conditions. In the regulatory context, countries like the USA, UK, Canada, Colombia, and South Africa have faced similar obstacles. While the Federal Communications Commission (FCC) in the USA and Office of Communications (Ofcom) in the UK have allowed unlicensed access to TVWSspectrum, regulation in countries like China and Singapore is still developing, exploring hybrid approaches [3; 21; 22; 23]. The Ofcom, the UK's communications regulator, has set the maximum EIRP parameter at 36 dBm, which aligns with the standardization by the Federal Communications Commission (FCC) in the USA. Regarding PSD restrictions, Ofcom limits power to 30 dBm over an 8 MHz bandwidth (BW), whereas the FCC specifies the same 30 dBm but over a 6 MHz BW. The BWs refer to the spectral range available for each TV channel in both countries. Concerning OOBE attenuation, the FCC has standardized an attenuation greater than 55.4 dB in adjacent channels. Conversely, Ofcom has traced distinct attenuation values based on device classes, setting a minimum attenuation of 43 dB for Class 5 devices. The HAAT parameter is defined as 250 m by the FCC, whereas Ofcom does not consider the average antenna height to the ground. The Canadian industry adheres to the definitions and standards implemented by the FCC [21; 24; 25; 26; 27; 28]. The Agencia Nacional del Espectro (ANE) in Colombia has established a maximum output power level delivered to the antenna of 30 dBm and a maximum antenna gain of 14 dB. The BW of TV channels in Colombia is 6 MHz, and the OOBE attenuation was defined with the same standardized values as the FCC. The maximum HAAT for antenna installation is 800 m. Lastly, the Independent Communications Authority of South Africa (ICASA) regulated parameters, especially focusing on projects using TVWS to expand internet access in rural areas. They set EIRP restrictions for each 8 MHz channel at 41.2 dBm for rural areas and 36 dBm for urban areas. As defined by Ofcom, the values for OOBE attenuations are determined according to device classes, with values greater than 43 dB for Class 5 devices and values greater than 74 dB for Class 1 devices [29; 30; 31]. Regarding frequency bands designated for TVWS services, there is a predominant focus on standardizing frequencies in the Ultra-High-Frequency (UHF) band, but this may vary from country to country.