5G offers faster download speeds than previous cellular standards, but depending on the frequencies used by base stations, the technology may not provide coverage close to that of 3G and 4G networks.

One of the frequency ranges used by 5G is millimeter wave (mmWave), with frequencies ranging from 30 GHz to 300 GHz. The main disadvantage of mmWave-based mobile 5G is that wireless high-band technology doesn't work well indoors. This is because mmWave signals have difficulty penetrating building walls and certain types of glass, hindering indoor 5G performance.

In fact, since AT&T and Verizon first deployed mmWave 5G in 2019, users have found it difficult to access high-band 5G signals. While users can get fast mobile 5G download speeds in excess of 1 Gbps if they're outdoors and near a 5G cell tower, that's not always feasible for people in the office or working from home.

Small cells improve indoor coverage

Cellular small cells are one solution to this coverage problem. First introduced in 2009 as part of the 3rd Generation Partnership Project 4G LTE specification, these wireless access points (APs) can increase the density of cellular networks.

Small cells are low-power cellular base stations that operate on a variety of frequencies. Depending on their size, small cells can provide transmission ranges from 40 feet to several kilometers. These mini base stations return to the main cellular network via an Ethernet, fiber optic or wireless connection.

Small cells can be deployed indoors or outdoors. Indoor varieties are usually small—about the size of a pizza box. These mega- or gigabit-speed gadgets can be mounted on ceilings and walls in homes and offices to boost the radio frequency (RF) signal strength of cellular networks.

5G networks increasingly rely on indoor small cells. This trend is likely to continue as more 5G small cells are deployed in offices, homes and apartments.

Operator Development in Indoor 5G Cyberspace

Indoor access to 5G wireless technology is becoming more common as U.S. mobile network operators (MNOs) deploy low-band and mid-band 5G cellular networks.

The three major U.S. mobile carriers — AT&T, T-Mobile and Verizon — now offer a mix of low-, mid- and high-band 5G networks, although those carriers don’t yet have full coverage of the U.S. with 5G frequencies.

With the continued rollout of macro networks, general 5G access -- both indoors and outdoors -- is better than it was a few years ago. Additionally, as cellular 5G networks expand, major operators are deploying small cells to expand and enhance coverage.

Verizon

In January 2021, Verizon, the largest U.S. mobile network operator, announced it would lease 15,000 small cells from shared communications infrastructure provider Crown Castle to support its nationwide 5G rollout by 2025. Once operational, each 5G radio will be leased for 10 years. The deal complements the thousands of 5G small cells Verizon has built itself.

The carrier is launching new C-band mid-band 5G spectrum to expand its 5G ultra-broadband service to reach 175 million potential customers in the US by the end of 2022. Verizon said it will deploy the initial expansion of small cells compatible with the C-band spectrum at a later date.

T-Mobile

U-T-Mobile, the second-largest U.S. mobile operator, also signed a deal with Crown Castle to deploy 35,000 small cells by 2027. These units are leased for 12 years. At a conference in January 2022, Crown Castle CFO Daniel Schlanger said the T-Mobile deal is "the largest small cell order in our history."

Verizon and T-Mobile are competing over which carrier will provide the fastest and densest 5G coverage in the United States. Small cells will be a big part of the push in 2022 and beyond.

AT&T

AT&T, the third-ranked mobile network operator, said it is working to reduce the time it takes to acquire a site and obtain a license to deploy small cells. In February 2022, AT&T said it was conducting field testing and deployment of commercial Ericsson Street Radio 4402 small cells in several US cities.

It can take 12 to 18 months for mobile network operators to add new micro 5G sites. Any infrastructure that can be deployed in less time is an advantage for operators. However, AT&T did not disclose how many indoor or outdoor small cells it plans to deploy.

How can small cells help 5G indoor coverage?

Despite ambitious plans by major mobile network operators, most 5G small cells will be deployed by private companies. IDTechEX predicts that by 2031, there will be 45 million 5G small cells distributed globally.

Some of these small cells will be installed by companies looking to create their own private 5G networks for businesses. By combining a private 5G core with a small cell network, businesses can implement secure, reliable, low-latency, and high-speed private networks locally.

Despite the private 5G hype, the technology to support these proprietary enterprise networks is only just beginning to become available. Private 5G deployments won't become mainstream until 2025 or 2026.

Meanwhile, businesses will continue to install indoor small cells, even though tiny radios connect to the mobile network operator's public network.

Increasing 5G network densification will greatly improve indoor coverage. As mentioned, indoor environments are not particularly friendly to high-band mmWave 5G radios. Walls can completely block high-frequency signals, but even mid-band 5G radios can be attenuated by office partitions and furniture.

Businesses requiring employees to access high-speed (above 1 Gbps) data downloads over cellular networks will require multiple mmWave small cells to ensure reliable, uninterrupted indoor data coverage.

Most 5G small cells deployed will likely use mid-band or low-band frequencies. These bandwidths are not entirely dependent on compatible indoor micro radios to provide coverage, but businesses that rely on stable 5G signals indoors should consider installing mid-band 5G small cells.

Distributed Antenna System

Many businesses use distributed antenna systems (DAS) to transmit cellular signals from a central source throughout the building. Small cell networks can complement these systems to improve indoor mobile coverage.

DAS providers, such as CommScope and Corning, work with major operators to install indoor antenna systems in hotels, hospitals, large office buildings, and stadiums. However, according to cellular signal enhancement provider Waveform, deploying DAS is more expensive than installing one or more small cells in a building, and the cost depends on supported frequencies and equipment.

Wi-Fi 6

Many smaller businesses can use Wi-Fi to provide employees with indoor mobile coverage, especially since most available cell phones now support Wi-Fi calling. Modern Wi-Fi 6-802.11ax access points increase throughput and reduce congestion on public network bandwidth. Compared to previous Wi-Fi standards, Wi-Fi 6 is more interoperable with 5G, enabling a more heterogeneous network when using both technologies.

Key players in the indoor 5G space

Notable players in the 5G small cell market include (in alphabetical order):

1. AirSpan
2. Cisco Systems
3. CommScope
4. Ericsson
5. NEC Corporation
6. Nokia
7. Samsung

In 2019, the blacklisting of Chinese suppliers Huawei and ZTE led to a split in the global radio access network market, including small cells. In the US and parts of Europe, Chinese suppliers are banned from selling telecom infrastructure. In the rest of the world, Huawei is the largest telecom provider.