2.4 GHz Regulatory Compliance (ETSI/FCC/MIIT)

To ensure interoperability, minimize interference, and maintain safe radio frequency emissions, Bluetooth Low Energy (BLE) devices must comply with regulatory requirements in each region where they are sold. The three major regulatory bodies governing radio frequency behavior are:

• ETSI (European Telecommunications Standards Institute)

• FCC (Federal Communications Commission)

• MIIT (The Ministry of Information Industry Technology)

Each of these regulatory bodies imposes its own limits on frequency usage, hopping behavior, and transmit power. Additionally, features like Adaptive Frequency Hopping allows BLE devices to avoid interference by dynamically modifying its hopping pattern to ensure compliance, especially in relation to channel usage and power classification.

For more details, please look into How to Certify Your Bluetooth Product

1. ETSI (European Telecommunications Standards Institute)

   In Europe, Bluetooth Low Energy (BLE) devices must comply with the ETSI EN 300 328 standard, which governs radio equipment operating in the 2.4 GHz ISM band under the Radio Equipment Directive (RED). The regulation specifies technical requirements for transmit power, receiver performance, spurious emissions, among other. All of these with the goal to ensure coexistence with other devices and limit radiated power. Therefore, the devices must be tested and manufacturers should apply to get the CE mark to indicate compliance.

2. FCC (Federal Communications Commission)

   The FCC regulates radio frequency devices in the United States, including Bluetooth Low Energy (BLE) products, under Part 15 of the FCC rules. BLE devices operate in the 2.4 GHz ISM band and must comply with strict limits on output power, spurious emissions, and bandwidth usage. Products must undergo FCC testing and certification, and they are assigned a unique FCC ID to indicate compliance, which must be labeled on the device or included in the documentation.

3. MIIT (The Ministry of Information Industry Technology)

   In China, Bluetooth Low Energy (BLE) devices are regulated by the MIIT, with specific technical requirements managed by the State Radio Regulation Committee (SRRC). BLE operates in the 2.4 GHz band and must adhere to rules on maximum transmit power, and strict controls on spurious emissions. The certification process includes local lab testing and submission of documentation to MIIT.

The following section will present the available configurations at the BLE Stack level that can be enable to help in the process of complying with each of the regulations for the CC23xx or CC27xx devices.

TX Power Limitations

The Radio Control Layer (RCL) enables the control of the TX output power associated with a radio operation. The user can select the regulation or group of regulation in SysConfig in the RCL module under RCL Tx Output Power Limitation. This configuration allows you to:

1. Set the regulatory domain using SysConfig.

2. Multiple regulations can be selected, however the RCL will use the most restrictive regulatory domain when programming the output power value (i.e., the smallest value applicable) if multiple regulations are selected.

3. The RCL will check the power limitation table to ensure the output power is within the regulatory domain and frequency or channel restrictions.

4. If needed, the regulatory domain can be modified at runtime.

Figure 159. SysConfig - Select Regulation for Tx Power Limitation.

Adaptivity FHSS using DAA (Detect and Avoid)

The Bluetooth standard makes it possible for the communicating devices to agree on which channels to use from the 37 available data channels during communication. If the master device (channel map update procedure can be initiated by the master only) detects high interference on a channel, it can initiate a channel map update. Adaptive frequency hopping (AFH) means that the communicating devices are continuously monitoring their environment for interference and are continuously changing the channel map to address the interference. Depending on the regulatory body in a given region, there are different requirements for AFH. For example, in Europe (ETSI) and China (MIIT), AFH is only a requirement when using TX power over 10dbm. In the US (FCC), AFH is only required if going over 20dBm.

These are the restrictions that apply to it according to the MIIT:

Adaptivity FHSS using DAA	Limitation
Channel availability	A channel is considered unavailable if it’s not used for 1 second or more or 5 x N x Channel Occupation time, whichever is larger. This ensures proper identification of long-term interference.
Channel Holding time	A BLE device can occupy a single channel for a maximum of 40 ms. If it holds it for longer, it must be idle for at least 5% of the dwell time, and not less than 100 us, before using it again. This prevents overuse of any single channel.
Short Control Transmission signals	Devices can transmit control signals even on Transmissions allowed on unavailable channels as long as duty cycle is less or equal than 10%. This allows minimal necessary traffic for control without violating spectrum fairness.

The following section will describe how to enable the Adaptivity module in SysConfig:

Open SysConfig and go to BLE → Advanced Setting → and check the Adaptivity using DAA checkbox.

Figure 160. SysConfig - Enabling Adaptivity using DAA

Once the module is enabled, the Adaptivity Configuration panel should appear in SysConfig. There are two Utilization Based Modes that allows your application to select the level of control for transmit (TX) usage on BLE channels.

1. Adaptative Mode: when channel utilization exceeds a defined threshold, then Adaptivity will be enabled.

   

   Figure 161. SysConfig - Adaptative Mode

2. Fixed Mode: adaptivity is always enabled whenever the TX power is above 10 dBm.

   

   Figure 162. SysConfig - Fixed mode

In both cases, the total transmit (TX) power (Pout) gain is in dBm and is set to 0 if not used. The valid range is -20dBm to 20dBm (negative value allowed to supports board attenuation).

Figure 163. SysConfig - External gain power set to 0 dBm by default

This should include gain from any external PA as well as any antenna gain. This will relax the detection threshold level (TL) according to the formula:

TL = -70 dBm/MHz + 10 × log10 (100 mW / Pout)

where TL is the detection threshold and Pout is the equivalent omni-directional radiated power in mW.