RFUWB Frequencies, Channels, Bandwidth, and EIRP Explained
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This article explains UWB (Ultra-Wideband) technology, its frequencies, channels, bandwidth, and EIRP (Effective Isotropic Radiated Power) as used in various applications.
Ultra-Wideband (UWB) technology utilizes wide frequency channels, typically spanning several GHz, to enable high data rate, low power and precise ranging applications. The allocation of UWB frequency channels varies by region, with major bands defined by regulatory bodies such as the FCC and ETSI, ensuring minimal interference with existing narrowband and wideband systems.
What is UWB Technology?
UWB stands for Ultra-Wideband, a radio technology defined in IEEE 802.15.4a. The primary application of UWB is accurate distance and location measurement. It achieves this by precisely estimating the time it takes for radio frequency signals to travel between two devices.
Compared to Wi-Fi and Bluetooth Low Energy (BLE), UWB provides more accurate distance/location estimations, especially in noisy environments with multipath interference. Wi-Fi and BLE typically rely on Received Signal Strength Indicator (RSSI) for distance calculation, which is less accurate because signals can be affected by walls and reflections.
UWB has been adopted by major smartphone and device manufacturers and finds use in industries like healthcare, automotive, and factory automation. Like Wi-Fi and BLE, UWB operates in unlicensed spectrum, potentially leading to widespread adoption.
UWB is exceptionally fast, potentially 50 times faster than GPS, and can update location data up to 1000 times per second, surpassing BLE beacon update rates.
Here are the key benefits of UWB technology:
- Ultra-Accurate Distance Estimation: Provides centimeter-level resolution.
- High Reliability: Highly immune to multipath and other types of interference.
- Low Latency: Can be 50 times faster than GPS.
- Affordable: Low power consumption and lower cost contribute to affordability.
- High Refresh Rate: Offers refresh rates from 200 to 1000 times per second.
- Secure: Employs distance bounding protocols as per IEEE 802.15.4z.
UWB Channels vs. UWB Frequencies vs. UWB Bandwidth
The following table outlines UWB channels, their corresponding center frequencies, and bandwidth.
| UWB Channels | UWB Center Frequency | UWB Bandwidth | Region Used |
|---|---|---|---|
| 0 | 399.36 MHz | 499.2 MHz | USA |
| 1 | 3494.4 MHz | 499.2 MHz | USA, Europe |
| 2 | 3993.6 MHz | 499.2 MHz | USA, Europe, Japan, Korea |
| 3 | 4492.8 MHz | 499.2 MHz | USA, Europe, Japan, Korea |
| 4 | 3993.6 MHz | 1331.2 MHz | USA, Europe |
| 5 | 6489.6 MHz | 499.2 MHz | USA, Europe, China |
| 6 | 6988.8 MHz | 499.2 MHz | USA, Europe, China |
| 7 | 6489.6 MHz | 1081.6 MHz | USA |
| 8 | 7488 MHz | 499.2 MHz | USA, Europe, Korea, China |
| 9 | 7987.2 MHz | 499.2 MHz | USA, Europe, Japan, Korea, China |
| 10 | 8486.4 MHz | 499.2 MHz | USA, Europe, Japan, Korea, China |
| 11 | 7987.2 MHz | 1331.2 MHz | USA, Japan, Korea |
| 12 | 8985.6 MHz | 499.2 MHz | USA, Japan, Korea |
| 13 | 9484.8 MHz | 499.2 MHz | USA, Japan, Korea |
| 14 | 9984 MHz | 499.2 MHz | USA, Japan, Korea |
| 15 | 9484.8 MHz | 1354.97 MHz | USA, Japan, Korea |
As seen in the table, UWB frequencies fall into sub-GHz band (UWB channel 0), Low band (UWB channels 1 to 4), and High band (UWB channels 5 to 15). Since UWB uses unlicensed spectrum, anyone can establish a communication link using a UWB transmitter and receiver without needing a regulatory license, as long as the system operates within the specified frequency and power limits. The FCC has allocated frequencies from 3.1 to 10.6 GHz for UWB applications. The UWB spectrum is further divided into various UWB channels, although not all channels are used in all regions.
UWB EIRP Limits
The following table specifies UWB EIRP limits for different UWB frequencies.
| UWB Frequency | EIRP |
|---|---|
| 960 to 1610 MHz | -75.3 dBm |
| 1610 to 1990 MHz | -53.3 dBm |
| 1990 to 3100 MHz | -51.3 dBm |
| 3100 to 10600 MHz | -41.3 dBm |
| Greater than 10600 MHz | -51.3 dBm |
The FCC restricts maximum radiation power to -41.3 dBm within the 3.1 to 10.6 GHz range. The figure above illustrates EIRP limits for frequencies outside of this range.
Conclusion
UWB’s large bandwidth, often exceeding 500 MHz, allows for high temporal resolution and robustness against multipath effects, making it ideal for applications like indoor positioning, radar sensing and secure communication. Additionally, the low Effective Isotropic Radiated Power (EIRP) limits imposed by regulations ensure minimal interference with other wireless technologies while maintaining efficient short range communication.
Overall, the combination of wide bandwidth, regulated frequency allocation, and controlled EIRP levels makes UWB a powerful technology for precise localization, secure data transmission, and emerging IoT applications.
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