Outdoor wireless backbone networks, typically seen in cellular backhaul network architectures, are well-established. But they aren’t enough; private 5G networks, the Industrial Internet of Things and AI- and ML-enabled assembly line and other machinery are requiring more and more indoor bandwidth. Indeed, there’s a growing need for “indoor” backbone networks with multi-Gigabit capacity.
As for consumer/residential, more evidence of the need for increased indoor bandwidth comes from the latest “Mobility report” from the OEM Ericsson. More and more people are going completely wireless, and the concept of a “landline” is becoming as uncommon as a rotary-dial phone.
So, when Ericsson notes that the global total number of high-bandwidth 5G subscribers is about to reach 1.6 billion and that, as has been the case for years now, 80% of cellular connections originate or terminate from indoor locations, the need for increased indoor connectivity becomes quite apparent.
At the core of the 5G standard are reduced latencies and much higher data rates. It’s these higher data rates that are resulting in poor indoor penetration from macro cells deployed on towers. To achieve higher data rates within a given channel structure (i.e., the same as 4G) designers had the options of using higher modulation or more complex MIMO arrays.
Both of these require higher quality signals, which are more sensitive to signal degradation from penetrating exterior walls. Basically, the higher capacities supported by 5G result in poorer propagation and hence indoor penetration. And propagation versus data rates is now a core tenet—or trade off—for all wireless systems.
To address the need for better indoor cellular connectivity, carriers are looking at 5G mid-band TDD and indoor small cells—as solutions for significantly improving network performance in these locations.
Deployments of small cells will make Gigabit-speed indoor backbone networks even more of a necessity, and wireless would be the most efficient way to link them. This is seen particularly in conference centers, hotels and stadiums—where most, if not all, professional sports teams are offering fans a host of 5G-enabled amenities.
Recall that indoor networks were initially composed of Ethernet or a co-ax cable plant, and these cables were initially deployed for both backbone (e.g., riser cable systems in tall buildings) and access purposes. Eventually Ethernet won that “battle,” and RJ-45 jacks became ubiquitous on wall outlets and computers. Then in 1999, 802.11b Wi-Fi was released and entered the market as an indoor access solution and it was essentially a way for users to connect to a location’s backbone without wires. Indoor connectivity eventually evolved to include cellular connectivity, but again, for access purposes only.
Over the last 20+ years, Wi-Fi technology and standards have improved to the point that relatively high-performance and ease of connectivity are a given and, as an indication of that progress, today it’s almost impossible to find a laptop with a built-in Ethernet port—another sign of the shift to “all wireless” connectivity. There are now numerous wireless devices with nomadic and mobile capabilities and the availability of ever-increasing access speeds make wireless the preferred approach for all indoor connectivity.
But looking at indoor connectivity on a big picture basis, wireless has never been used for indoor backbones for a few reasons: