Reading the Tea Leaves on 5G/Wi-Fi Convergence

To most end-users, wireless is just wireless: “Cellular, Wi-Fi, whatever, just get me to my digital content and applications.” This in itself is an extraordinary achievement. The fact that consumers can shift from cellular to Wi-Fi multiple times per day without even noticing is a testament to how far we’ve come as an industry. These are two very different technologies, using different standards, backed by different hardware and silicon ecosystems, that work so well together, that end-users rarely think about it. So, when someone asks about Wi-Fi/cellular convergence, it’s fair to just point to their smartphone: We’ve got convergence right now!

Of course, when analysts ask that question, that’s not really what they mean. “Convergence” in this context implies something deeper, a closer marriage of the world’s two great wireless technologies down to the level of the standards themselves. Advocates for deep convergence argue that enterprise and industrial customers would benefit from tighter integration than what today’s Wi-Fi/cellular “coexistence” approaches deliver. Are they right? Do the benefits of deep convergence justify the costs and effort needed to achieve it? Or can coexistence get us where we need to go? 

These are some of the biggest open questions in the wireless industry today. The good news is that we’re about to start getting some answers.

Driving Towards Convergence

Up to now, Wi-Fi has dominated the enterprise space, with cellular reserved for a handful of specialized use cases. The emergence of private 5G networks, however, is starting to shift that status quo, with cellular making real (albeit early) inroads into the enterprise. As it does, we can expect the buzz around convergence to grow louder, especially from customers themselves. 5G/Wi-Fi convergence can offer significant benefits in areas like:

• Mobility: The ability to seamlessly combine indoor Wi-Fi with outdoor cellular connectivity could prove extremely valuable, especially for use cases like connecting autonomous vehicles roaming indoor/outdoor campuses. 
• Resiliency: Enterprises could combine 5G and Wi-Fi to provide better coverage in any space. For the most mission-critical applications, they could even use both simultaneously. 
• Security: Some industrial customers would benefit from the ability to authenticate all devices via 5G cores, even as some operate over Wi-Fi or mixed networks. 
• Differentiation: Many cable operators now act as Mobile Virtual Network Operators (MVNOs). New enterprise solutions that tightly integrate private/public 5G with Wi-Fi could prove a compelling offer. 

Some of these use cases could be supported by more sophisticated coexistence, where 5G and Wi-Fi play more nicely together, even as they continue existing as separate technologies. Others, however, such as those requiring guaranteed end-to-end quality, would likely need deeper convergence. 

Evolving Standards

The industry is well aware of the potential advantages of convergence and is already working to enable it. 3GPP Release 16, for example, introduces mechanisms to allow non-cellular devices to access 5G core networks for the first time, and defines frameworks for steering and splitting traffic across the network. This work, however, is still in its infancy, supporting only basic convergence capabilities.

Meanwhile, in the Wi-Fi space, ongoing standards evolution is adding 5G-like features and control. Wi-Fi 6/6E, for example, uses Orthogonal Frequency-Division Multiple Access (OFDMA) schedulers to enable granular access prioritization for critical applications. Looking a few years down the road, the two technologies begin to look even more alike, using similar architectural capabilities for things like beamforming, handling large MIMO arrays, and other operations. 

Overcoming Barriers

So, as Wi-Fi and cellular overlap, should we assume that eventually, these terms will mostly just refer to different spectrum allocations for a single, overarching wireless technology? Probably not. There remain significant barriers to deeper convergence. 

At the most basic level, converged 5G/Wi-Fi capabilities would need to be supported by both networks and devices. That means two massive ecosystems with thousands of stakeholders, each with its own business priorities, evolving together to achieve deep convergence. 

Even if everyone were on board, they would still face significant technical hurdles, including: 

• Handoffs: Configuring an iPhone to switch to Wi-Fi when available is relatively simple. Setting up a mixed industrial network to connect autonomous robots with guaranteed quality and resiliency end to end is another matter entirely. Different devices and applications may require different policies on when to switch from one network to the other, based on signal level, quality, who owns a given in-range base station, and many other factors. These policies get incredibly complex. 
• End-to-end service mapping: Along those lines, enterprises would need some mechanism for Quality of Service (QoS) mapping and policy interworking across Wi-Fi and cellular—an extremely complicated proposition.
• Authentication: How will converged networks ensure trusted connectivity? If convergence requires every device to use a Subscriber Identity Module (SIM) card, it will be limited to a very small subset of devices and use cases. 
• Testing and monitoring: The challenge isn’t just to implement unified policy and QoS frameworks. We also have to test and validate them under diverse mission-critical scenarios. How do you guarantee service continuity when moving between networks? If a device encounters degraded performance after switching, what happens? How do you even know? Those details and many others need to be figured out, and that work has not started.

Looking Ahead

The future of convergence entails many open questions. As more enterprises explore private 5G, however, we’ll start getting answers. For example, one of Wi-Fi’s most durable advantages has been low costs. Can enterprises reduce capital outlays by replacing large Wi-Fi deployments with fewer 5G small cells? Or will ongoing operating costs keep Wi-Fi less expensive? Or consider performance. In theory, 5G supports guaranteed ultra-low latencies, but will it actually deliver? 

Enterprises and vendors are working through these questions right now. As they do, we should see progress on the biggest question of all: What level of convergence do we actually need? As private 5G networks bump up against existing Wi-Fi infrastructures, the industry will have no choice but to hash out some of the complexities. Understanding where Wi-Fi and cellular clash, where deeper convergence could prove most useful, and which use cases are really viable—the next few years should bring some clarity.

Hopefully, this process also stimulates fresh perspectives among today’s Wi-Fi and cellular partisans. After all, when it comes to wireless standards, enterprise customers aren’t all that different from consumers. They just want to connect their applications, with the performance, reliability and features they need, at a cost that makes sense. When we can give customers that without making them worry so much about how everyone wins.