The role of antenna quality in small cell and 5G deployments

Mobile network operators are densifying their network infrastructure to both meet ever-increasing data demands and to lay the groundwork for 5G.

While the importance of fiber, spectrum availability and ease of siting are often discussed in network equipment deployments, one overlooked factor is the impact that antenna quality has on the efficiency, effectiveness and total cost of ownership of such deployments.

Here are three ways that antenna quality impacts small cell deployment:

Quality antennas have fewer impairments and failures, reducing TCO. 

The worst-case scenario for antennas is complete failure, which means they must be replaced. That can delay site turn-up or require a site visit. Antenna design and manufacturing company Kathrein estimates that for a cellular network with 40,000 antennas, a 2% failure rate will cost the MNO nearly $1 million per year in site visits costs.

Short of failure, antenna quality also impacts how consistently and well an antenna performs — which directly influences user experience. Low-quality components or insufficient attention to passive intermodulation (PIM) during design and testing can mean that an antenna doesn’t perform according to the expectations of network planners, resulting in poor coverage, blocked or dropped calls or impacts to throughput, according to Dr. David Kokotoff, senior sales engineer at antenna design and manufacturing company Kathrein.

Kokotoff said that besides the extensive controlled mechanical and environmental testing in the lab, Kathrein has a number of sites around the world where it tests its antennas in challenging environmental conditions. These sites keep equipment in the field to observe what happens over years of exposure to the elements: in salt-exposed environments near the sea and in hot and humid conditions. The extensive, long-term testing, he said, contributes to improving overall reliability and keeping Kathrein’s antenna failure rate at less than 0.05%.

As antenna complexity increases, so does the importance of quality. 

Kokotoff noted that with MNOs needing support for both low- and mid-band spectrum as well as support for carrier aggregation and multiple-input multiple-output (MIMO), License-Assisted Access and CBRS spectrum, the number of ports has increased: eight, ten or more ports are commonly requested. Supporting multiple bands in a small-volume base station while achieving the desired performance is no small feat, especially when proper isolation must be maintained. Rigorous PIM testing and high-quality compatible component selection also becomes important to ensure consistent antenna performance in the complex urban RF environments where small cells are most needed.

Thoughtful design features can make installation and management easier. 

Remote electrical tilt is a feature more commonly associated with macro site antennas, but Kokotoff said that Kathrein has recently introduced RET to its small cell antennas. MNOs used to think that they could avoid small cell interference through site selection, he said, but optimal sites are not always available or affordable. Features such as RET can offer MNOs the ability to tweak their small cells’ coverage and get what they need from the sites that they can most easily access.

Antenna design also needs to account for the real-world challenges of installation. Many models of light poles, for instance, have a wide base but a thin pole that make it difficult to fit all the necessary cables that need to run to the multi-port equipment placed at the top. Kathrein has tackled this via the use of diplexers internal to the antenna to minimize cable runs.

Since small cells need to be placed close to end users, aesthetics of the equipment and the ability to creatively place antennas also come into play. Kathrein has focused its efforts on “out of sight, out of mind” design for small cells, including building-corner and side-mounted options and even antennas that can be placed underground to provide street-level coverage.

Learn more about Kathrein’s antenna portfolio.