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An introduction to neutral host networks using private 5G

Enterprises often use signal boosters and distributed antenna systems to improve carrier signal strength. Neutral host networks over private 5G could disrupt those methods.

Enterprises have long had wireless woes that traditional technologies like Wi-Fi can't handle. Private LTE and 5G over free-to-use spectrum -- such as Citizens Broadband Radio Service, or CBRS, in the U.S. -- could help address some of those issues.

Another compelling reason to use CBRS has recently emerged: neutral host networking. Neutral host networking is a cost-effective architecture that uses private 5G to extend public carrier cellular signals into locations or areas with poor signal strength.

Here's what enterprises should know about neutral host networking and what it can do for both small and large businesses.

Improving cellular signal strength

Cellular voice and data networks have exploded since the advent of the smartphone, and access to these networks has become a must-have for enterprises. But one drawback of cellular networks is they often struggle with limited signal penetration. When this issue occurs, carrier signals can't reach certain areas within a corporate building or campus.

One way for businesses to fix this problem is to extend their carrier signal to areas where connectivity is poor, said Srinivasan Balasubramanian, distinguished member of the CTO office and head of standards and IP at Celona Inc. Businesses traditionally extend the signal by using a signal booster or distributed antenna system (DAS). While these methods work, they have their shortcomings.

According to Balasubramanian, boosters are useful only if the carrier signal is undistorted enough to amplify. DAS, on the other hand, is an easier way for businesses to extend their signal to all parts of a building, but the cost of implementing it is too expensive for most organizations.

"There are plenty of scenarios where neither solution solves this problem, and it's here where neutral host shines," Balasubramanian said.

Neutral host networking is a way to propagate public carrier network access across a privately deployed wireless network.

What is neutral host networking?

Neutral host networking is a way to propagate public carrier network access across a privately deployed wireless network. The technology uses the internal switching architecture of a building, along with private LTE or private 5G. Businesses can connect to carrier networks over encrypted tunnels via the internet.

From there, network professionals can use the LAN and 5G radio access network (RAN) in the building or campus to propagate the signal over a private channel, such as CBRS Band 48. Any CBRS-capable cellular device can then access the public carrier network as if it is directly connected to it.

How neutral host networks work

Two or more mobile network operators (MNOs) can deploy neutral host networks by connecting to the corporate LAN through an encrypted IPsec tunnel across the internet, Balasubramanian said. The tunnels terminate at the 5G RAN core gateway device. From there, the signal securely travels across the corporate LAN and toward the 5G RAN access points deployed throughout the building.

The carrier signal then extends throughout the building via a CBRS channel, and carrier traffic travels the corporate network using a secure IPsec tunnel, Balasubramanian said.

"To ensure operability and performance is maintained, key performance indicators are exchanged between the 5G RAN core and the service providers," he said.

Who should deploy neutral host networks?

New use cases for deploying neutral host networks are emerging. One reason why enterprises might consider deploying a neutral host network would be when their facilities require public carrier connectivity to perform operations, Balasubramanian said. For example, the business could use a private 5G network internally and use the neutral host network to improve signal strength and capacity, he added.

Another use case he cited for neutral host networks is to grant employees or customers with guest access to public carrier networks. Some examples include university campuses, hospitals and public or private venues.

Diagram portraying how two 5G RANs can create a neutral host network.
Here's how a typical LAN and LTE or 5G RAN can facilitate neutral host.

"In these situations, public carrier access via neutral host networks may be the primary driver for deploying a private 5G network, with the option to use private RAN when those opportunities arise," he said.

In the past, these organizations would typically deploy DAS, he said. Now, they might prefer to use neutral host networks over 5G as a more cost-effective and flexible alternative.

Neutral host networking outlook

Neutral host networks aren't yet available in the U.S. But cooperation between private CBRS RAN manufacturers and nationwide cellular carriers is ongoing. For example, Celona is working with U.S. carriers to broadcast public carrier services over CBRS bands. Other MNOs are working to develop neutral host networks around the world. In Europe, for example, Ericsson is partnering with Proptivity to launch the first neutral host network in Sweden later in 2022 as an indoor 5G service.

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