What frequency bands are allocated for 5G NR millimeter wave and how do they differ globally?
5G mmWave Spectrum
The allocation of millimeter wave spectrum for 5G varies significantly across regions, creating challenges for global device compatibility and economies of scale.
- Performance verification: confirm specifications against the application requirements before finalizing the design
- Environmental factors: temperature range, humidity, and vibration affect long-term reliability and parameter drift
- Cost vs. performance: evaluate whether the application demands premium components or standard commercial grades
Frequently Asked Questions
Why is mmWave 5G not deployed as widely as sub-6 GHz?
Several factors limit mmWave deployment: (1) Coverage: mmWave cells have much smaller coverage radius (100-300 m) than sub-6 GHz cells (1-5 km). Covering the same area requires 10-100× more base stations. (2) Cost: each small cell costs $10K-50K (hardware + installation + backhaul). Deploying thousands of small cells per city is expensive. (3) Propagation: mmWave signals do not penetrate buildings well (15-40 dB through exterior walls). Indoor coverage requires dedicated indoor small cells or repeaters. (4) Device cost: mmWave front-end modules add $10-30 per device. Most mid-range and budget phones do not include mmWave. (5) Use cases: the primary motivation (multi-Gbps throughput) is not yet critical for most users. Sub-6 GHz provides 100 MHz - 1 Gbps, sufficient for current applications. mmWave deployment is focused on: dense urban areas (stadiums, transit hubs), fixed wireless access (last-mile broadband), and enterprise/industrial (factories, campuses).
What is the difference between n257 and n261?
n261 (27.5-28.35 GHz) is a subset of n257 (26.5-29.5 GHz). n261 was defined specifically for the US FCC allocation (the LMDS band at 28 GHz). A device that supports n257 automatically covers the n261 frequency range. However: a device designed only for n261 covers only 850 MHz of the 3 GHz n257 band, and would miss the 26.5-27.5 GHz and 28.35-29.5 GHz portions used in other countries. For global compatibility: support n257 (the superset). Most mmWave chipsets (Qualcomm SDX55/60/65) support both n257 and n261 with the same hardware.
Will mmWave spectrum expand beyond 52.6 GHz?
3GPP Release 17 extended FR2 to 71 GHz (FR2-2). Release 18 and beyond are studying extensions to: 90-100 GHz (W-band). 100-300 GHz (sub-THz). The ITU World Radiocommunication Conference (WRC) will consider additional mmWave allocations in future sessions. The 60 GHz band (57-71 GHz): already available as unlicensed spectrum in most countries (used by WiGig). 5G NR can operate here for short-range, very high throughput scenarios. Above 100 GHz: research-stage (6G). THz communications promise > 100 Gbps throughput for short-range links (< 10 m). Significant technical challenges remain (semiconductor technology, antenna design, atmospheric absorption).