Researchers at NYU Wireless, a research center of the New York University's Polytechnic School of Engineering, report promising findings that could enable 5G millimeter-wave (mm-wave) cells to be as large as several hundred meters, the same size as 4G cells in dense urban environments.
The research, presented in Microwave Journal, indicates that mm-wave frequencies (30 to 300 GHz) show great promise for the future of wireless because of the large raw available, unused bandwidth.
In particular, over 14 GHz of available spectrum exists in the 28, 38/39, and 73 GHz bands, making these bands great candidates for new mobile spectrum that will increase capacity by several orders of magnitude over today's cellular and Wi-Fi allocations, the researchers said, adding that recent advances in integrated circuit and antenna technology have made it possible to inexpensively and reliably manufacture wireless devices that operate at millimeter wave frequencies.
In the Journal, the researchers recount how their new measurement tools and soundings from the Manhattan and Brooklyn rooftops of NYU are positioning the United States to take advantage of high-frequency radio waves. The mm-wave spectrum was previously discounted because its tiny waves travel only short distances; popular opinion said that made them too easily obstructed by rain, leaves, buildings and bodies.
Professor Ted Rappaport, director of NYU Wireless, and student co-authors outlined their new tool, which uses National Instruments technology to measure mm-wave channels: a sliding correlator channel sounder system, which measures over very large bandwidths, even beyond line-of-sight conditions.
Earlier this year, Rappaport told FierceWirelessTech the vision for millimeter wave was in its infancy. He said there is a lot of spectrum available in the millimeter-wave bands--and there are many bands; 60 GHz is just one unlicensed band. It happens to suffer from 20/db per kilometer of additional loss in free space, due to oxygen absorption, but other bands don't have this additional deterioration.
As part of their research, the team tested in the 28 and 73 gigahertz bands, both outdoors and in a complex interior environment of a simulated office. The measurements, as well as the mathematical channel models, are designed to help engineers design future mm-wave wireless communications systems and will assist in the standardization process.
In October, the FCC issued a Notice of Inquiry (NOI) to examine the use of bands above 24 GHz for mobile broadband. The comment period is now underway, with reply comments due by Jan. 15, 2015. The NOC cites the research of NYU Wireless, "Small Wavelengths--Big Potential: Millimeter Wave Propagation Measurements for 5G," that was co-authored by doctoral students Sijia Deng, Christopher Slezak and George MacCartney.
This latest research also introduced extensive wideband mm-wave propagation measurements, as well as directional and omnidirectional path loss models and multipath spread characteristics. The measurements and modeling revealed potential for some simplified receiver structures, as well as for the formation and combination of specific transmitting beams to improve the signal-to-noise ratio.
5G reflects the wireless industry's increasingly rapid pace of change
Ericsson, NSN and NYU Wireless ramp up 5G efforts
NYU Wireless' Rappaport envisions a 5G, millimeter-wave future
NSN joins 5G research at NYU Wireless