Indoor 5G gets a boost with arrival of small cells

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), which has frequencies between 30 GHz and 300 GHz. The main drawback of mmWave-based mobile 5G is that the wireless high-band technology does not work well indoors. This is because mmWave signals have difficulty penetrating building walls and certain types of glass, which hinders indoor 5G performance.

In fact, users have found it difficult to access high-band 5G signals since AT&T and Verizon first deployed mmWave 5G in 2019. While users can get fast mobile 5G download speeds of over 1 Gbps if they are outdoors and close to a 5G cell tower, this is not always possible for people in offices or working from home.

Small base stations improve indoor coverage

Small cells are one way to solve 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 using a variety of frequencies. Depending on their size, small cells can provide a transmission range from 40 feet to several kilometers. These mini base stations connect back to the main cellular network via Ethernet, fiber, or wireless.

Small cells can be deployed indoors or outdoors. The indoor variety is usually tiny — 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 are increasingly reliant on indoor small cells. This trend is likely to continue as more 5G small cells are deployed in offices, homes, and apartments.

Operator Development of Indoor 5G Network Space

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

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, though those carriers don’t yet have full U.S. coverage with their 5G frequencies.

As macro networks continue to roll out, 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 extend and enhance coverage.

Verizon

In January 2021, Verizon, the largest mobile network operator in the United States, announced that it would lease 15,000 small base stations from Crown Castle, a shared communications infrastructure provider, to support its nationwide 5G deployment by 2025. Once operational, the lease for each 5G radio will last for 10 years. The deal complements the thousands of 5G small cell base stations that Verizon has built on its own.

The operator is rolling out new C-band mid-band 5G spectrum to expand its 5G Ultra Wideband service to cover 175 million potential customers in the U.S. by the end of 2022. Verizon said it will deploy small cells compatible with the C-band spectrum after the initial expansion.

T-Mobile

T-Mobile, the second largest mobile operator in the United States, has also signed an agreement with Crown Castle to deploy 35,000 small base stations by 2027. The lease period for these units is 12 years. At a conference in January 2022, Crown Castle Chief Financial Officer Daniel Schlanger said that the T-Mobile agreement is "the largest small cell order in our history."

Verizon and T-Mobile are in a race over which carrier will offer the fastest and densest 5G coverage in the U.S. 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 shorten the time required to acquire sites and obtain permits to deploy small base stations. In February 2022, AT&T said it was conducting field tests and deploying commercial Ericsson Street Radio 4402 small base stations in multiple cities in the United States.

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

How do small base stations 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 around the world.

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

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

In the meantime, businesses will continue to install indoor small cells, although the micro radios connect to the mobile network operators' public networks.

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

Enterprises that require employees to access high-speed (1 Gbps+) data downloads over cellular networks will need 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 don’t rely entirely on compatible indoor micro radios to provide coverage, but businesses that rely on a stable 5G signal 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 a building. Small cell networks can supplement these systems to improve indoor mobile coverage.

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

Wi-Fi 6

Many smaller businesses can use Wi-Fi to provide indoor mobile coverage for employees, especially since most available phones now support Wi-Fi calling. Modern Wi-Fi 6-802.11ax access points increase throughput and reduce congestion on public network bandwidth. Wi-Fi 6 interoperates better with 5G than previous Wi-Fi standards, 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

The blacklisting of Chinese vendors Huawei and ZTE in 2019 has split the global market for wireless access networks, including small cells. In the United States and parts of Europe, Chinese vendors are banned from selling telecom infrastructure. In other parts of the world, Huawei is the largest telecom supplier.