For mobile operators, the struggle to provide adequate service indoors becomes a full-on battle as they ramp up 5G networks.

In previous network buildouts, operators had some flexibility with service quality because so much of what they were building was to support on-the-go traffic. That provided a buffer between operators whose networks didn't always perform as advertised and consumers who initially used those networks for making calls.

As network technologies continued to progress from generation to generation, however, operators continued struggling to provide quality service in buildings, and consumers increasingly used networks for more data-hungry applications. Today, operators are faced with the reality that their customers' appetites for bandwidth can never be sated, and even the overwhelming majority of phone calls that take place on networks -- 80%, according to Informa -- do so from inside buildings.

As operators deploy 5G, they're faced with the reality that there is no room for flexibility when it comes to network quality. 5G networks are expected to support applications like 4K/8K video, virtual/augmented reality and the Internet of Things (IoT).

These applications, and most others supported by 5G, require impeccable network coverage indoors, which has always been a challenge, regardless of the technology deployed. And the problem with providing that impeccable coverage is basically the same as it's always been: Buildings are filled with materials that block radio signals, such as steel frames, metalized insulation and treated glass.

5G makes the problem more complex because of its high-frequency transmissions, which shorten the range. For an application that needs 300GB per second, for instance, will need to operate over 28GHz on the 5G network. That means the signal range will be extremely short and easily interruptible by a something as thin as a regular wall. It's definitely not going to work in a factory setting or in an underground mine, where 5G deployments are being touted to deliver the localized performance needed for things like ultra-reliable and low latency communications (URLLC).

Traditionally, indoor coverage has been provided through distributed antenna systems (DAS). But DAS doesn't play well in a 5G world. It doesn't support bands of 3.5GHz or higher frequencies found in 5G, and it's too complex to maintain for 5G networks. It's also expensive for operators that have to provide base stations at each site, as well as connectivity back to their core network.

Proponents like Huawei Technologies Co. Ltd. contend that indoor digitalization provides a viable alternative to successfully deploy 5G indoors. It supports a range of technologies with high data rates, including multi-carrier aggregation and distributed MIMO. Indoor digital networks also are backward compatible with 4G. This enables operators to reuse existing hardware, such as network and fiber optic cables, during 5G upgrades.

Indoor digital networks also give operators opportunities for adding new business and creating revenue, including the option of unleashing traffic in hotspots. Huawei works with operators to identify hotspots and calculate the potential return on investment (ROI). They've experienced hotspot identification accuracy of 85% and reduced ROI to less than four years using indoor digital networking solutions.

— Denise Culver, Director of Online Research, Heavy Reading