Essentially, beamforming focuses the radio signal. It's concentrated and stronger to an individual receiver such as a mobile phone or WiFi. It's sometimes described as "steering" the signal. It's been used in radar and sonar for decades. More recently, it's common in 802.11ac WiFi and built into some wireless standards. As processing power becomes cheaper with Moore's Law, more powerful systems become practical.
Eric Geir offers a lay explanation: "Wireless routers (or access points) and wireless adapters that don’t support beamforming broadcast data pretty much equally in all directions.
NYU Wireless has just reported on 14,000 tests using 28 GHz and 73 GHz indoors. The paper isn't online yet so I put the abstract below. Professor Ted Rappaport believes, "These high frequencies will be an effective substitute when today's Wi-Fi frequencies get crowded."
The FCC is about to set aside some high frequencies for telco use. My opinion, not Ted's is that monopoly spectrum is obsolete. Wi-Fi is proving sharing is possible and productive. Some monopoly spectrum is needed where reliability is important, but the 100 MHz Sprint, AT&T and Verizon each have is plenty.
Ted makes an important point. "I think the FCC would do well to also authorize unlicensed bands in the near vicinity of that new mmWave spectrum.
Most experts thought it would require fiber. Karolina Wikander is confident. "Microwave backhaul technology is already able to handle 100 percent of all radio access sites' capacity needs, both now and in the future. By 2020, the technology will have evolved to support multi-Gb capacities in traditional frequency bands and beyond 10 Gb in the millimeter wave."
Most plans for 5G assume extraordinary reliability. The telcos want to control traffic and connected cars. Failures there - including in massive snow or rainstorms - can cost lives. Controlling the cars may require 1 millisecond latency. One expert thought that would be impractical without fiber. (Dan Warren, a good engineer, wonders whether 1 millisecond is practical no matter the technology.) Update - Ericsson pointed out that microwave latency is low. See below.
Millimeter wave high frequency for the 5G network itself is deeply troubling for policy.
Gets ARCEP permission to test. Ted Rappaport at NYU has convinced the industry that high-frequency, millimeter wave wireless can work. But many questions remain. What are the effects of walls, windows, rain, and distance? We have only partial answers.
France Telecom/Orange intends to find out. They just receive approval for a year's worth of testing in the ancient city of Belfort. Much of the testing to date has been in Manhattan, Brooklyn and other highrise areas. Belfort is ideal for testing low-rise and suburban regions.
AT&T, Verizon cram 3-5 as many people on each cell site. AT&T 50,000, China Mobile 1,000,000, SK Korea 35,000, Spain 33,000. Currently, Albania, The Maldive Islands, and at least a dozen other countries have faster LTE networks than the USA. The chart is adjusted for population and AT&T obviously stands out. Verizon would be similar.
Since 2000, U.S. wireless networks have been far less reliable than many in Europe and East Asia, except for a brief period around 2010-2011.
Marty Cooper is right: If we are efficient, "There is no spectrum shortage and there never will be." Showing there's enough spectrum if used efficiently, Marcelo Claure concludes "[Our] spectrum holdings are sufficient to provide its current and future customers." Claure has ~100 MHz in high frequencies, so much he is thinking of using some of it for backhaul. (The FCC should stop that, and other many wasteful practices, in the name of efficiency. But true efficiency is generally ignored.)
Cooper, the inventor of the cell phone, was joined by Marconi Fellows A.J. Paulraj, John Cioffi and Vint Cerf in projecting technical advances that could raise wireless capacity 50-100 times. The engineers convinced me until the companies spent $45B in the last auction. That's 3-4 times as much as the experts I respect predicted. I don't think anyone well informed is certain of next year's results.
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