Indoor cellular systems have been around for decades. But with the generational shift from 4G to 5G, they are widely expected to become even more necessary and widespread.
There are several reasons for these expectations of growth. For one, most cellular data use happens indoors, and mobile devices are continuing their rapid proliferation and using even more data. Cisco’s Annual Internet Report estimates that by 2023, there will be 8.7 billion handheld/personal mobile devices globally, and 4.4 billion machine-to-machine/IoT devices. By 2023, Cisco estimates that there will be 3.6 connected devices per person on a global basis, with 45% of devices connected via cellular networks and 55% via Wi-Fi or wired connections. In North America specifically, that figure is even higher: an average of 13.4 networked devices/connections per person are expected.
Meanwhile, devices that used an average of 1.5 GB of data per month in 2017 are expected to use 9.7 GB of data per month by 2022. Ericsson’s Mobility Report estimates that for smartphones in North America specifically, the average monthly use will rise from about 8.5 GB in 2019 to 45 GB per month by 2025. And given that an estimated 80% of cellular data traffic originates indoors, that means a substantial increase in the strain on indoor networks, even if the traffic is split between cellular and Wi-Fi.
The second reason, particularly for operators such as AT&T and Verizon, is that the initial spectrum that has been available to them for 5G services have been high-frequency, millimeter-wave bands. mmWave makes possible multi-gigabit speeds that simply can’t be achieved in the single channels available at lower frequencies, but that performance comes with a hefty price in propagation. mmWave has several inherent characteristics that make it challenging to use: Among them is its propensity to reflect rather than penetrate surfaces, and its vulnerability to being stopped short by external building materials, particularly low-emissivity glass. Again, in-building penetration issues aren’t new for cellular systems – but signal vulnerabilities have even stronger influence and signal behavior is different in higher bands, to the extent that outdoor-in coverage simply will not be able to be relied upon for indoor public or private networks that need the speed, low latency and high capacity that 5G mmWave systems can provide. Indoor systems of some type are a must-have.
The third reason has to do with 5G strategy. While consumer-focused 5G applications and devices are obviously part of that strategy, mobile network operators are also very keen to sell 5G to a wide variety of enterprises and forge deeper relationships with manufacturers, warehousing and logistics providers, transportation hubs, commercial real estate/smart building owners, healthcare and other verticals. Many of those 5G network implementations will come in indoor environments. Some of them will be wholly private networks, with enterprises owning or leasing their own spectrum; some will host a combination of networks for guest/public use, internal operations and/or IoT. High-definition video and real-time analysis/video processing from fleets of security cameras, cameras monitoring industrial production lines, or for distribution, replay and AR/VR experiences in large-venue sports and entertainment, are just some of the high-bandwidth demands that will be best supported by 5G, accompanied by multi-access edge computing (MEC).
Many of the services that 5G will support will be business-critical, and thus the networks will have to have sufficient coverage, capacity and reliability for businesses to depend on them – for this, outside-in coverage alone won’t be good enough. As Caroline Gabriel, principal analyst at Analysys Mason, recently wrote, the prioritization of outdoor macro networks over indoor coverage in current and former generations of wireless networks led to indoor coverage holes and dropped calls that “undermined many enterprises’ efforts to implement mobile-first strategies. … In turn, this limited operators’ ability to monetize their networks.
“The indoor quality of experience must no longer take a back seat in the 5G era if enterprise requirements are to be satisfied,’” Gabriel wrote. “For the first time, operators and businesses have a strong motivation to invest in in-building wireless networks to the same extent as outdoor networks. … For the first time, networks will be deployed where the importance of the indoor quality of service is equal to that of the outdoor quality of service, rather than being an afterthought.”