巴西：ANATEL釐清5150-5350 MHz頻段在車輛應用中的室內環境定義

巴西國家電信局（ANATEL）近期發佈第 81/2025 號官方函件，進一步釐清5150-5350 MHz 頻段在車輛應用中的室內環境定義。本次澄清依據Act 14448/2017第3.1.48和11.2 條，旨在統一對不同類型車輛的法規解釋。

根據ANATEL的定義，室內環境指的是能夠透過建築物屏蔽效應降低傳輸訊號衰減，進而減少多方向輻射的環境。基於此定義，ANATEL確認5150-5350 MHz頻段（WLAN B1/B2）僅可用於完全封閉的車輛，例如轎車和卡車，因其結構能有效模擬室內環境。

另一方面，開放式車輛（如摩托車、機動三輪車及敞篷車）不得使用該頻段，因為這些車輛缺乏能確保訊號衰減並限制輻射的封閉結構，因此不符合現行法規的要求。

此外，官方函件進一步確認，適用於陸地運輸車輛的相關法規，僅適用於被歸類為封閉式室內環境的車輛。其中包括火車，因其與封閉式汽車和卡車類似，能夠有效減少無線電頻率的發射影響。

Brazil: ANATEL Clarifies Definition of Indoor Environments for 5150-5350 MHz Frequency Use in Vehicles

The Brazilian National Telecommunications Agency (ANATEL) has issued Official Letter 81/2025 to provide further clarification on the definition of indoor environments regarding the use of the 5150-5350 MHz frequency range in vehicular applications. This clarification aligns with items 3.1.48 and 11.2 of Act 14448/2017 and aims to harmonize regulatory interpretations across different vehicle types.

According to ANATEL, an indoor environment is one that provides attenuation of transmitted signals due to building penetration, thereby reducing emissions in multiple directions. Based on this definition, ANATEL has determined that the 5150-5350 MHz frequency band (WLAN B1/B2) may only be used in fully enclosed vehicles, such as cars and trucks, which effectively simulate an indoor environment.

Conversely, open vehicles, including motorcycles, tuk-tuks, and convertible cars, are not permitted to use this frequency band. These vehicle types lack structural enclosures that would ensure signal attenuation and limit emissions, as required under the regulatory framework.

The official letter further confirms that the regulations for land transport vehicles apply only to those classified as having a closed indoor environment. This includes trains, which, like enclosed cars and trucks, provide adequate attenuation for radiofrequency emissions.