5G Era Might Create Opportunities in Indoor Mobile Infrastructure

Smartphone and IoT device coverage Indoors is possibly a qualitative change in the U.S. mobile market, not just a qualitatively more challenging development. That is exemplified most clearly by the characteristics of millimeter wave spectrum, which does not readily pass through building walls.

That means a greater percentage of transmission infrastructure has to shift to specialized indoor modes. And that, in turn, means the opportunity for new business arrangements to supply that capacity. Some believe that means a new segment of the market could emerge for providers of neutral host indoor facilities.

Indoor coverage has been a growing issue since the advent of the 3G era, as more capacity has been supplied by mid-band spectrum in the 2-GHz region.

The rule of thumb for capacity, as embedded in the 3GPP channel models is that 80 percent of traffic originates indoors and 20 percent outdoors, notes Michael Murphy, Nokia Networks CTO, North America.

During the cold winter months in the north, and warm months in the south, there is even less traffic outdoors. Still, in the 4G era, service providers have continued to rely on outdoor macrocells to serve users indoors, despite the growth of specialized indoor solutions (distributed antenna systems, Wi-Fi offload, smaller cells).

Millimeter wave frequencies in the 24-GHz, 28-GHz and 39-GHz regions are going to part of the U.S. 5G platform. Signals in those regions will not easily pass through walls.

source: Nokia Networks

There are a couple of logical solutions for indoor coverage. Service providers might opt to use  low- or mid-band spectrum outdoors, and millimeter wave indoors.

Another approach is to use new mid-band spectrum, particularly the 3.7 GHz to 4.2 GHz band.

Yet another approach is to deploy millimeter wave indoors, possibly with a neutral host platform based on small cells.

And, of course, some will favor connectivity based on Wi-Fi offload.

Inevitably, because of divergent mobile service provider spectrum assets, cable TV operator perception of their assets, differences in network load based on customer volume, ownership of fixed network assets and spectrum strategies, different suppliers are going to use different combinations of those approaches.