mmWave propagation key to delivering mobile 5G
Verizon will launch a 5G mobility service based on 3GPP’s 5G New Radio standard in Chicago and Minneapolis on April 11, a major milestone in a process that started more than two years ago, Vice President of Network Engineering Mike Haberman told RCR Wireless News.
In October Verizon turned up its fixed wireless 5G Home service, based on the company’s Verizon Technical Forum standard, in four markets–Houston, Indianapolis, Los Angeles and Sacramento, using its 28 GHz millimeter wave spectrum. This offering averages around 300 Mbps with peak speeds in the 1 Gbps range.
As the carrier transitions from fixed to mobility and from the proprietary specifications to 5G NR, Haberman reflected on the journey. “This actually started a long time ago,” he said. “We had our trial system in 2017. We had our 5G Home deployment in the four cities starting October last year. That was really the start—getting experience with millimeter wave, the propagation. Even though [5G Home is] a fixed deployment, it still does handoff and all those other sort of things. It’s been a learning process. Learning how to test it, getting the proper equipment to test it. And then you need to think about is the air interface is so quick, all the stuff behind it still needs to be able to support those higher data rates. This has been a long journey.”
In Chicago, Verizon subscribers with the Motorola Moto z3 equipped with the 5G “mod” will be able to access the next-gen network in The Loop, Gold Coast, River North, Old Town and the Magnificent Mile Verizon store. Coverage in Minneapolis will initially be available in Downtown West, Downtown East, Eliot Park and the Verizon store at Mall of the Americas.
Haberman said users should expect enhancements in both throughput and latency. He said the speeds associated with 5G Home are advertised “fairly conservative,” and noted the similarities between the VTZ and 5G NR technology sets. “The theory is generally the same. The characteristics will be the same. Obviously there will be some improvements” with the transition to the global standard. “Then what you’ll see after that is you’ll see more and more technology layered on it just like we did with LTE. You’re putting the platform out there that can evolve tremendously going forward.”
Haberman said the bulk of the mobile 5G network has been deployed at existing LTE radio sites although there are some 5G-only sites. In terms of delivering a consistent experience using millimeter wave spectrum in the context of the dense built environment of Chicago, Haberman said the propagation issues aren’t markedly different from with LTE bands and noted the millimeter wave is “a little more controllable.”
“If you take a step back,” he said, “4G is line-of-sight too, but we take advantage of reflections. 5G is really the same way. You’ll find a lot of reflections. That’s what enables 5G to get in places you don’t expect. You may not have view of the cell site, but you can certainly be talking to it. It’s about propagation, it’s about probability.”
Using highly granular modeling tools, Verizon uses a technology called ray tracing wherein environmental and factors like building location and materials provide a visualization of how RF will propagate throughout a given coverage area.
“The way it works is–some of it is limited to what you can put on a pole obviously–you’ll see a lot of two-, three-sector sites out there and obviously if it’s two it’s two 180-degree sectors, if it’s three, it’s three 120-degree sectors. There are discrete beams that you can use. Then what happens is the system is smart enough that it’ll pick the element in the antenna that’s actually facing a customer or it might face the multi-path. That way it focuses the energy on that one element within that one sector. It cuts off the transmit on all the other elements in that sector. It’s forming based on the feedback it’s getting from the mobile [device].”
He continued: “The benefit of it is obviously you’re not transmitting, you’re not spraying it, over that 120-degrees. The interference is greatly reduced. If you can reduce the interference, you have the same carrier, you increase the gain of the carrier because you’re focusing the carrier. You can actually improve the link budget quite a bit, which is what helps you out with millimeter wave.” An improved link budget equates to an improvement in signal quality and coverage distance.
To the infrastructure piece, Haberman said Verizon is deploying on towers, street lights, traffic lights, utility poles and, in some locations, street furniture like kiosks. For fiber, the carrier is using a combination of owned and leased fiber.
