n257 (28 GHz)

Overview

The 28 GHz band remains the world's most trialled / tested 5G band. Development of the 28 GHz band is ongoing and is headed up by 3GPP TR 38.815. Like all mmWave bands, n257 is a capacity layer designed for short range transmission with high data rates.

The interest surrounding the 28 GHz band is largely due to a combination of three factors;

• Spectrum Availability: large portions of the spectrum are underutilised, allowing several hundred megahertz to be dedicated to 5G services
• Device Complexity: of the available mmWave bands, 26 and 28 GHz bands are the lowest frequencies available, providing better propagation and reduced device complexity
• Geographical Harmonisation: of the available mmWave bands, the 28 GHz frequency range is available in the greatest number of countries across the globe.

Standardising a single 28 GHz band would not be practical as to cover the entire 24.25 to 29.50 GHz range would require RF devices to handle a 5.25 GHz wide bandwidth. As such three bands were defined to cover the three geographical groups:

• n257: Covering 26.5 to 29.5 GHz for Japan, North America, and South Korea
• n258: Covering 24.25 to 27.5 GHz for Europe and China
• n261: Covering a narrower 27.5 to 28.35 GHz for operation alongside n260 (39 GHz) in the United States