Testing Reveals 5G Propagation Is Better Than Expected

AT&T plans further tests at 28 GHz
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WASHINGTON — We’ve been covering the coming of 5G a lot in the virtual pages of Radio Magazine Today. I’m left wondering if there is more hype than substance though, due to the nature of propagation of millimeter wave radio signals. 

“The classic mobile business model is built on “outside-in” network coverage using radio base-stations deployed hundreds of meters, or even kilometers, apart,” according to this article in lightreading.com. “Each base-station can connect 1,000 or so users making it a very efficient way to connect large numbers of customers to a valuable service.”

“The issue is that a lot of the growth in demand is indoors. The penetration loss from buildings turns these indoor users into, effectively, cell edge users, reducing cell capacity/efficiency and limiting end-user performance. Energy efficient windows, now often fitted as standard in new buildings or renovations, only add to the problem,” according to the same article.

[Will 5G Be an Effective Media for Broadcast Radio in the Future?]

So, will that model limit the success of 5G? It turns out that the changing nature of the business of “mobile” may be a saving grace for the millimeter-wave bands though, and 5G may very well rely on a different model altogether—with small cells being built indoors. “In the enterprise, there are some interesting new approaches to small cells that can loosely be described as vRAN architectures...There are also opportunities in mmWave, which is a technology well-suited to indoor environments with lots of multipath. And given the large amount of spectrum in these bands, there are some very interesting opportunities for mesh systems using relaying and multi-hopping techniques,” the same article goes on to say.

Perhaps concerns about poor propagation at milli-meter frequencies are overblown. “Millimeter-wave signals were more found to be more robust than expected and provided high speeds — although not gigabit speeds — at distances of several thousand feet from a node, Signals Research Group found in recent testing of Verizon’s 28 GHz fixed wireless access network in Houston, reports rcrwireless.com. “Millimeter wave signals are far more resilient than we expected, even at distances exceeding several thousand feet. Tree foliage, passing school buses, buildings, glass, and parked cars impacted the received signal, but the resultant signals were still capable of delivering meaningful data rates,” SRG concluded.

Despite those concerns, it’s full speed ahead on 5G for AT&T. The company wants to demonstrate 5G using the 28 GHz band when it hosts its SHAPE conference on June 2–3 at Warner Bros. Studios in Burbank, California, according to fiercewireless.com, and it applied with the FCC for Special Temporary Authority (STA) to demonstrate the functionality, features and capabilities of 5G using experimental equipment.

The plan for the demo will involve communications between three fixed base stations and six user equipment (UE) devices within 100 meters of the base station antennas. The base station and the UE antennas will be placed indoors at a height of less than four meters in a room or open space inside a building or on the ground in front of a building within the Warner Bros. Studios perimeters in Burbank.

AT&T has promised to launch a “standards-based” mobile 5G service in a dozen cities in the United States before the end of this year, according to the same article. Company executives have said the operator will offer a mobile “puck” device in time for the launch. 5G smartphones are not expected to be available until 2019.

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