Wi-Fi has undergone a significant transformation in recent years, inching closer to 5G technology's capabilities. This evolution has enabled Wi-Fi to handle over 90% of fixed network traffic, surpassing even cellular usage from smartphones. 

As smartphone data usage starts to level off and evidence shows 4G's continued dominance in serving cellular connections, this raises an intriguing question: should 5G take a page from Wi-Fi's playbook?

Wi-Fi and cellular integration 

Wi-Fi 6 introduced Orthogonal Frequency Division Multiple Access (OFDMA). OFDMA allows multiple users to share the same communication channel, much like 5G. Advancements in the Institute of Electrical and Electronics Engineers (IEEE) standards have also added new low-latency and high-reliability capabilities essential for Time Sensitive Networks (TSNs).  

Wi-Fi 7 is now available with Multi-Link Operation (MLO). This is equivalent to 5G's Carrier Aggregation (CA), which combines different radio links to increase throughput and relieve network congestion. Wi-Fi 8 aims to perfect MLO to ensure smooth transitions between access points.  

Looking to the future, 6G network requirements are emphasizing consistent user experiences across different locations, including deep indoor coverage. National wireless infrastructure strategies reinforce these requirements, promoting seamless transitions between different network types, both public and private, to meet diverse user and application needs. This network-of-networks strategy combines outdoor public networks with denser indoor networks deployed by shared infrastructure companies (neutral hosts) and private enterprises. 

For the past few decades, private and public networks have been integrated, with a focus on merging local private Wi-Fi networks with nationwide public cellular networks. The 3^rd Generation Partnership Project (3GPP) has specified over a dozen tightly integrated architectures for combining Wi-Fi and cellular. However, the standout method adopted has been the loosely coupled ePDG-based approach used to support Wi-Fi calling.

Streamlining Wi-Fi handovers with 3GPP 

In 2023, Cisco's analysis revealed that mobile operators in over a hundred countries have deployed the ePDG approach to incorporate private Wi-Fi access into broader service offerings. Over time, LTE's ePDG approach will give way to 5G Stand Alone (SA) architecture's "Non-3GPP Inter-Working Function" (N3IWF), which will further streamline Wi-Fi handovers. 

The OpenRoaming federation, built on a similar loosely coupled approach, is revolutionizing the ease of roaming onto private networks. The Wireless Broadband Alliance (WBA), which runs OpenRoaming, has updated the rules to let this system work with not just traditional Wi-Fi, but also private 5G networks in the future. 

The UK Government-funded project 5G Diversified RAN Integration and Vendor Evaluation (5GDRIVE), has concentrated on integrating public and private networks. Cisco joined forces with Virgin Media O2, Wavemobile, Ori, and Warwick University to explore how the new 5G roaming interface, known as N32, could work between public and private networks.  

Interconnecting private 5G networks 

Cisco's contribution included providing a private 5G network (delivered as-a-service) and demonstrating how adapting N32 interface's transport using the 3GPP defined Security Edge Protection Proxy (SEPP) could simplify integrating 3GPP roaming with private networks. Tweaking the N32 specification allows for OpenRoaming-like capabilities that enable connectivity across the network-of-networks, dramatically reducing the complexity of integrating with thousands of private networks. 

Over the past 18 months, Cisco and Intel, both co-chairs of WBA’s OpenRoaming initiative, have collaborated on a 3GPP release 19 study item to determine the best way to interconnect private 5G networks. The 3GPP SA1 meeting in February approved the study's conclusions, leading to new 5G requirements related to private 5G "cellular hotspots." These hotspots will offer service in a manner similar to Wi-Fi hotspots. Their aim is to support the widespread adoption of private 5G networks by providing settlement-free service to many credential holders, including public cellular providers and private enterprises.  

With SA1's work complete, the responsibility now shifts to 3GPP's SA3, and CT4 groups to finalize the 5G cellular hotspot specifications by late 2025. This timeline allows for collaboration with broader industry forums to ensure 5G cellular hotspots can be integrated into the wider network-of-networks concept. 

Network-of-networks private 5G 

The focus of private 5G is now shifting from earlier efforts to operate using unlicensed spectrum. Unlicensed 5G is limited by the same emitted power restrictions and co-existence regimes that constrain the operation of Wi-Fi networks.  

Instead, private 5G operation using newly allocated shared spectrum is accelerating. Regulators worldwide are delivering novel licensing regimes to support 5G adoption by private enterprises. The powerful work of 5GDRIVE, 3GPP, and the OpenRoaming federation points to the possibility of how best to deliver a scalable network-of-networks and private 5G systems. 

As we embark on this journey, industry stakeholders must consider how these developments will shape the future of connectivity. Are we ready to fully embrace the opportunities offered by integrating public and private networks into a network-of-networks? What might the implications be for consumers and businesses alike? Your thoughts and perspectives are welcome as we navigate this exciting frontier. 

Read more about Wi-Fi 7 and what’s new in the latest release in our blog: Onward and upward with Wi-Fi 7.