Confront challenges in 5G non-public networks

5G private networks will have more capabilities and broader appeal than LTE private networks. Planning, implementing, and maintaining a 5G private network has unique challenges for deployment and test.

Private networks — also known as non-public networks (NPNs) — let organizations or groups of organizations use wireless networks to guarantee coverage and maintain network control. LTE-based NPNs for enterprises have gained traction in recent years because they support industrial IoT and Industry 4.0 use cases, displacing industrial networks that had typically been hardwired or utilized other wireless technologies.

Maximizing manufacturing speed, efficiency, and process quality control is, of course, the main driver for industrial cellular private network deployments (Figure 1). Today, when we think data is more valuable than oil and security vulnerabilities are a primary concern, a growing number of organizations are moving to adopt private networks to keep their data secure. Also, with operations becoming increasingly dependent on wireless networks, some firms would prefer to maintain control over their own networks to avoid being at the mercy of a service provider.

5G brings new and more advanced technologies that heighten the appeal of private networks. Each of 5G’s most highly touted sets of services — ultra-reliable low-latency communications (URLLC), massive machine-type communications (mMTC), and enhanced mobile broadband (eMBB) — are compelling to industrial operations. In Figure 2, an engineer uses a wireless connection to keep an eye on a manufacturing process.

The case for 5G private networks has become even more compelling in 2020. In July, 3GPP completed Release 16, which added 5G support for NPNs. Release 16 also adds support for time-sensitive networking (TSN) based on IEEE 1588, a crucial ingredient for the co-existence of 5G private networks and Ethernet. This is an essential upgrade because many factories and other facilities that will feature private networks will also continue to employ different types of networking technologies. Finally, 3GPP Release 16 also added support for unlicensed spectrum, which some private networks will utilize depending on the deployment scenario.

Analysts predict private network deployments will increase dramatically in the coming years. Deloitte’s Technology, Media, and Telecommunications Predictions 2020 report forecasts that more than 100 companies worldwide will have begun testing 5G private networks by the end of 2020. The consulting company predicts that the value of equipment and services used in private networks will rise sharply and be worth tens of billions of dollars per year by 2024.

While Smart Factory/Industry 4.0 use cases are the most obvious candidates for 5G networks, manufacturing facilities will by no means be the only places to use them. Office environments of private companies and government agencies are also showing greater interest in private networks, in part because 5G makes private networks more attractive for all use cases and in part because the COVID-19 pandemic has reinforced the value of connectivity to organizations of all sizes.

Deployment scenarios
3GPP specifications support several options for private network deployments (Figure 3). One option is the deployment of an independent, standalone network. Under this deployment model, all network functions are located within the facility where the network operates, including the radio access network (RAN) and control plane elements. Standalone, isolated private networks would typically use dedicated spectrum (licensed or unlicensed) purchased through a mobile network operator (MNO) or, in some cases, directly from government agencies.

A second major 5G private network deployment scenario involves an NPN sharing a radio-access network (RAN) with the service provider. Under this scenario, control plane elements and other network functions physically reside at the NPN site. This type of deployment enables local routing of network traffic within the NPN’s physical premises, while data bound for outside premises is routed to the service provider’s network. 3GPP has specifications that cover network sharing. (A variation of this deployment scenario involves the NPN sharing both the RAN and control plane functions, but with the NPN traffic remaining on the site where the NPN is located and not flowing out to the public network.)

The third primary type of NPN deployment is where the NPN is hosted directly on a public network. In this type of deployment, both the public network and private network traffic are located off-site. Through virtualization of network functions in a technique known as network slicing, the public-network operator of the private network partitions between the public network and the NPN, keeping them completely separate.

Each of the above NPN deployment scenarios has its own advantages and disadvantages, depending on the exact parameters and use cases for the network.

Regardless of the specific deployment model chosen, the creation of all 5G private networks will have a design/planning phase, a deployment/acceptance phase, and an operation/optimization phase. The following are some tips to keep in mind for each phase.

Design/planning phase: Spectrum clearance
Spectrum clearance is among the most critical challenges for the successful deployment of 5G private networks. Identifying sources of interference is crucial because interference can severely hamper network quality. Particularly for Smart Factory/Industry 4.0 applications, degradation of signal quality created by interference can decimate the efficiency of manufacturing process control and monitoring.

Conducting spectrum clearance for setting up a private network can be broken down into three steps. First, identify and map sources of interference. Next, hand over the location, frequency, and spectral shape to “interference hunting teams” to find the unwanted source of transmission. Finally, eliminate the source. This can be a very labor-intensive and time-consuming process, but it can be accelerated dramatically using an automated interference identification system.

Acceptance testing
Acceptance testing is a significant challenge to the deployment of 5G private networks for several reasons. First, every deployment has its own unique obstacles based on the use case and the layout of the physical structure where the private network is to be deployed. Again, depending on the use case, the requirements for network reliability, data throughput, and latency can vary widely. On top of that, the relative immaturity of 5G technology can add additional layers of complexity to the task of acceptance testing.

A sound methodology for private network acceptance testing provides for initial optimization and also fine-tuning and continuous optimization over time, taking into account that deployment sites — particularly manufacturing facilities — can be unforgiving and dynamic environments in which to operate a wireless network.

Field testing of a 5G network should involve multiple user equipment (UE) devices, including the latest smartphone, tablet, and other UEs that may be utilizing the network. A comprehensive test plan will involve walking or driving the entire premises served by the network, taking thousands of measurements.

Operation/optimization phase: Monitoring and benchmarking
Monitoring of 5G private network quality and capacity levels is necessary for three primary reasons: to ensure optimized coverage across the entire range of the network, maintain mission-critical communications, and increase the quality of experience (QOE) of network users.

Public and private networks continually evolve. Continuous test and monitoring of a network requires test methodologies and tools that can adapt with them. Test methodologies should always reflect the latest developments in specifications from 3GPP and other relevant networking standards bodies.

Critical items to benchmark:

• Data connection: file download speed, file upload speed, network latency, web browsing time, and the performance of over-the-top (OTT) applications.
• Voice and video quality: completed call rate, call setup success rate, dropped calls, blocked calls, call setup time, mean opinion score (MOS).

Conclusion
The deployment of private networks will grow. 5G private networks are brand new, and there are plenty of kinks to be worked out. But performance, bandwidth, and security advantages that 5G brings to the table are too attractive for organizations — particularly manufacturers — to pass up. Like all networks, each 5G NPN deployment will feature its own unique challenges. 5G private network deployments will require smart, well-planned, and evolving design and test strategies to succeed.

Dylan McGrath is a veteran technology journalist and former editor in chief of EE Times. He is now a senior industry solutions manager at Keysight Technologies.