The use of millimeter-wave spectrum has evolved in the 5G era, and these high-band airwaves are playing significantly different roles in current networks than they have in previous generations of cellular technology.
High-band frequencies used to primarily appear in mobile networks as point-to-point backhaul links, which were often relied upon by public safety and other private networks, as well as in some cases for backhaul of consumer-facing cellular networks. Commercial network backhaul systems operate in spectrum up to 90 GHz.
Given that history, it’s not surprising that one of the first mmWave applications that emerged for commercial use has been Fixed Wireless Access, according to Russel Lindsay, senior product manager for Anritsu’s handheld field instruments. FWA relies on a mmWave link to provide high-speed home internet service, such as Verizon’s Verizon Home, and it does so by connecting with Customer Premise Equipment (CPE) at an individual residence. Designing a network of fixed links for mmWave is a simpler proposition than a network which supports mobility and site-to-site handoffs. To be sure, though, ensuring that the signal is able to penetrate the home to reach CPE installed indoors, or sending a technician to install an external antenna that will ensure the signal reaches the CPE, each represent their own challenges, Lindsay added.
As 5G has evolved over the past two years, mmWave has begun to appear in city centers.
As that happens, “I think what you’re seeing is installation starting in ‘safer’ type of environments,” said Lindsay. Those “safer” environments include places with relatively open areas and a high density of users — places like New York’s Times Square or other popular nightlife areas in cities. “They’re able to do much better planning of how coverage will work,” Lindsay explained. That includes accounting for the behavior of individual beams from sites and the extent to which they can “track” with user devices, as well as considering multi-path signal reflections. Coverage mapping becomes important for optimization, Lindsay adds, because the ability to go out with an instrument and an antenna and track the beam behavior enables operators to have detailed information about coverage strength and quality and the interactions of user devices with neighboring sites.
In addition to city centers, mmWave is being used to cover specific, targeted large venues such as sports and entertainment complexes and transportation hubs. These are also locations with a defined area and a high density of users, and operators see a business case for being able to provide exceptional speeds and low latency, and laying the groundwork for advanced applications — often by also implementing multi-access edge computing at the site and working closely with both the venue owner and an application developer to showcase the utility of 5G. Verizon, for instance, this fall began a series of announcements of cities where it has both deployed its mm-Wave-based 5G service and combined that capability with local computing resources from AWS Wavelength.
The first two applications that the carrier highlighted were from ShotTracker and Avesha Systems. ShotTracker uses data from sensors on players, in basketballs and around a sports arena to create an “indoor GPS”, and the positional data runs through algorithms to give real-time statistics. It has utility for sports broadcasts, for coaches and trainers and athletes themselves and even for sports betting. Avesha Systems, meanwhile, supports an application that uses artificial intelligence and rapid compute processing to provide an “extra set of eyes” during routine surveillance scans of the colon to detect cancer.
The role of mmWave may shift even further in dense areas, so that the spectrum straddles both the Radio Access Network and transport networks. This could be accomplished with integrated access backhaul (IAB): the ability to use mmWave access spectrum to both serve UEs and to wirelessly backhaul traffic from 5G sites, eliminating the need to trench fiber. “Access spectrum has historically been too valuable and limited to use for backhauling,” Ericsson explains in a technical breakdown of IAB. In fact, 3GPP explored the same concept for LTE, but the available spectrum resources meant that it never gained commercial backing. In 5G, however, there is so much mmWave spectrum available that it may make sense to use some of it, in some places, for backhaul.