Last week, ANATEL issued Official Letter 81/2025 to clarify and harmonize the definition of indoor environments for the use of 5150-5350 MHz frequency range, particularly in vehicular applications, in accordance with items 3.1.48 and 11.2 of Act 14448 (Click here to access Act 14448).
According to ANATEL, an indoor environment refers to an environment with conditions to provide attenuation of transmitted signals due to building penetration, thereby reducing emissions in multiple directions (definition in item 3.1.1 of Act 14448).
Based on this definition, ANATEL has established that the 5150-5350 MHz band (WLAN B1/B2) is allowed only in vehicles with a fully enclosed structure (simulating an indoor environment), such as cars and trucks. Therefore, this band cannot be used in open vehicles, including motorcycles, tuk-tuks, and convertible cars.
See below the official letter text in English:
- We hereby acknowledge receipt of Letter OFFICIAL_SEI_COMMITTEE OCDS_057_25, registered under number 13205985, of SEI Process number 53500.006776/2025-25, through which the OCDs Committee requests guidance from Anatel regarding the application of items 3.1.48 and 11.2 of the Technical Requirements for the Conformity Assessment of Restricted Radiation Radiocommunication Equipment, approved by Act No. 14448/2017, in motorcycles, Tuk-Tuks and convertible cars.
- Considering the definition of “Closed environment (indoor)” in subitem 3.1.1 of the Technical Requirements attached to Act No. 14448/2017, which states: “is one capable of producing attenuation by penetration in buildings in order to allow the emission levels of a transmitter to be degraded in several directions.”
- Considering that subitems 3.1.48 and 11.2 of the annex to Act No. 14448/2017 prescribe that:
- Land transport vehicle: vehicle intended for the transport of cargo or people whose interior is considered a closed environment (indoor) for the purposes of this document. The provisions of this item also apply to trains.
- 11.2. The following provisions apply to access point transceivers operating in the 5,150–5,350 MHz band installed inside land transport vehicles and trains.
- Please note that the above rules do not apply to the vehicles in question, as they do not guarantee obstacles that allow the degradation of the emission levels of a transmitter in different directions.
For more details, click here to open the official letter from ANATEL website.
Feel free to contact us if you have any question: sales@e3tech.com.br
