By: Slavko Djukic

It’s hard to escape talk about 5G these days, even as 4G becomes more robust. Thanks to carrier aggregation, mobile network operators can leverage a number of separate LTE carriers in order to increase the peak user data rates and overall capacity of their networks, as well as exploit fragmented spectrum allocations. This will help the industry squeeze more capabilities out of 4G over the next few years. 

This current state of boosted 4G LTE as LTE-Advanced+ is a prelude to what will eventually become 5G, at least from the network speed perspective. While true 5G will be based on currently developing standards, final versions of which are still some time away, we have a basic idea of what we can expect from it.

5G’s primary promise is that it will grant access to vast amounts of new spectrum and allow wireless networks to support use cases never supported by 4G. This millimeter wave spectrum provides — at least by order of magnitude — wider bandwidths for mobile applications. But, it presents enormous challenges from an indoor propagation perspective.

Next, small but powerful base station antenna arrays using massive multiple-input multiple-output (MIMO) will combine beamforming with a massive network to extend the range of the signals and increase network efficiency.

5G networks will provide much less latency, which is one of the main requirements for critical use cases such as self-driving vehicles. These three qualities of 5G have the potential to almost triple the annual gain in wireless network capacity over the next decade versus the annual gain over the past 20 years, but these gains will not come without challenges.

Challenges of Indoor Coverage in 5G

Most outdoor 5G tests today use millimeter wave frequencies — 28 GHz and higher. Compare this with today’s mobile networks which use various frequency bands below 3 GHz to provide coverage over large areas.

There are significant challenges associated with using such high frequency bands, especially indoors. In a nutshell, higher-frequency radio signals are less capable of penetrating obstructions, which presents an immense problem in indoor networks.

The key to effective indoor mobile cellular coverage and capacity is a far-traveling, uninterrupted radio signal. Modern buildings are unfortunately the perfect countermeasure against radio signals because of the materials with which they are built, such as treated glass, steel frames, and metalized insulation. It’s hard enough for some of today’s licensed spectrum to get through building walls, and 5G’s high-frequency transmission will further complicate this.

The higher the frequency, the shorter the range. At even the low end of the projected 5G frequencies, the signal range will be very short. Even standard plaster walls will block the signal, let alone the high-tech building materials now used for modern construction.

And that’s a problem, because reliable indoor coverage is already an issue — one that will only get worse as true 5G comes into play.

Current Indoor Connectivity Challenges

The problem of poor indoor cellular coverage already is widespread, with 74 percent of U.S. workers in industries from hospitality to healthcare, warehouses to enterprises, saying they “frequently” or “sometimes” have problems with connectivity. Mobile coverage is essentially another utility these days – tenants and employees expect it the way they expect the lights to always turn on and the water to always run, and when it doesn’t work well, people notice immediately.

Connectivity is only going to become more critical in the future to enable employees to complete their tasks using the technologies that help them work most productively, and to ensuring those technologies are usable in the workplace. 5G will intensify in-building connectivity issues, impacting not just businesses within the buildings, but also commercial real estate (CRE) building and facilities managers who want to get top companies into their office space.

To meet current challenges of indoor connectivity, and to be ready for true 5G, some businesses are considering investing in a full-spectrum distributed antenna system (DAS) network, which best supports carrier aggregation features of today’s 4G and will be in the best position to support indoor 5G in the future.