Editor’s Corner—Integrating Wi-Fi with 5G no trivial matter

cell phones
The Wireless Broadband Alliance has called for industry cooperation to harmonize the integration approaches of Wi-Fi with 5G. (Pixabay)
Monica Alleven Editor's Corner

If it seems as though the industry has been talking about integrating Wi-Fi with cellular for a long time, it has—something on the order of 15 years or more. Now with 5G being all the rage, the Wi-Fi industry is making sure its voice remains relevant in those discussions.

It was a popular theme at the Wireless Global Congress event that the Wireless Broadband Alliance (WBA) held in London this week. The WBA has been advocating closer integration between cellular and Wi-Fi since about 2009, with the story evolving over the years from authentication to more complex things like seamless handover between the two and even “split-mode” use cases.

The organization published a report last week that outlines the options and alternative approaches available for combining access over Wi-Fi-based and cellular-based networks. The report defines three alternative approaches to integration: access-centric solutions, core-centric solutions and above-the-core centric solutions.

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“It’s not a question that 5G is going to solve all the problems and all the issues of connectivity; that’s not the point,” said Tiago Rodrigues, general manager of the WBA, in an interview last week. “We believe 5G is great,” but Wi-Fi is moving forward on its own path to 802.11ax, also known as Wi-Fi 6, and “we see a lot of merit on the integration of both those two technologies.”

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It's worth noting that in both Verizon's 5G Home service and AT&T’s upcoming mobile 5G, there’s a role for Wi-Fi. Even when trials were conducted at the Winter Olympics in South Korea with 5G delivered to people on buses, there was a Wi-Fi component on the bus.

The question I keep going back to in these discussions revolves around whether the cellular industry is taking Wi-Fi seriously when it’s defining the standards for 5G. The IEEE community has occasionally reached out to 3GPP for closer collaboration. Then again, a lot of the players, like AT&T and T-Mobile on the U.S. carrier side, are intimately involved in both 5G and the Wi-Fi, so they presumably are aware of what’s going on in both worlds.

“I think we have been given some positive steps forward,” Rodrigues said, noting Wi-Fi calling as one example of extending traditional cellular voice services to Wi-Fi and treating Wi-Fi as one more radio technology, similar to 2G, 3G and 4G.

Going forward, one of the areas where WBA believes it’s important for the industry to come together is around defining policy mechanisms. As Melody Eclavea, director of Interconnection Agreements at AT&T, told WBA Annual Industry Report 2019 author Monica Paolini, there’s a desire to be able to look at the conditions on the cellular network and the Wi-Fi network before deciding whether to connect the consumer to Wi-Fi’s Passpoint or not. (First introduced in 2012, Passpoint sets up in the background so the customer doesn’t have to do anything, but the connection to the device and the network is secure.)

In most cases, this is how offload works today: A mobile operator will send subscribers to a trusted Wi-Fi network when available without taking into account the performance and availability of the Wi-Fi and cellular network. Passpoint gives operators visibility into Wi-Fi performance in visited networks, so they can see if subscribers are better off using Wi-Fi or cellular in real time and use policy to decide who uses Wi-Fi and who stays on cellular.

The combination of Passpoint and policy takes operators beyond offload and gives them the control they want over the subscriber experience in both Wi-Fi and cellular networks and enables them to balance the traffic load over the two networks, Paolini explained.

Policy management is something Boingo Wireless has been working on as well. For example, with video applications, whether for something like Netflix or Hulu, it’s important for the initial setup that the connection should be fast at first. But because latency isn’t as big of a deal for video as it is for, say, voice, the network should act accordingly, i.e., voice gets the lower latency while video gets the requisite throughput.

The learning curve revolves around how to build the rules for different types of traffic so that the operator can take advantage of what’s inside a given venue—cellular or Wi-Fi, licensed or unlicensed—and use the network to the best of its ability without bothering the end user to do something. That’s where the industry is headed, according to Boingo Wireless CTO Derek Peterson, who serves as co-chairman of WBA.

As to whether the cellular industry is doing enough to bring Wi-Fi into the fold, Paolini said everybody has been trying for a long time to get Wi-Fi and cellular integrated, and success has been limited. It’s not a trivial matter. A Wi-Fi network is fundamentally different from cellular; it’s generally distributed with many small networks controlled by different entities and the device is basically attaching itself to a network. In a cellular network, it’s the network that grabs the device, so to speak. But attempts at better integration are also limited by the fact that so far, this stuff works pretty well.

“I think it’s crucial, it’s great, because it gives you better utilization of the resources that you have,” but it’s not exactly broke. “It’s the success of Wi-Fi that paradoxically has reduced the sense of urgency to integrate Wi-Fi and cellular in the past,” Paolini told FierceWirelessTech.

If you think about it, Wi-Fi carries 67% of the mobile traffic in the U.S., and in Japan, it’s in the 83% range. That’s hugely successful. From a mobile operator perspective, Wi-Fi and cellular integration will increase efficiency and improve subscriber experience, but it’s not an urgent problem because Wi-Fi already carries most of the traffic and users are mostly satisfied with it. However, there is growing support for the integration between the two technologies as operators realize the benefits of using policy and traffic management for both Wi-Fi and cellular, she noted.

Peterson said the industry is still in this Convergence 1.0 stage, with Wi-Fi and cellular being deployed in the same place but not necessarily being used at the same time. The capabilities exist to submit packets across both Wi-Fi and cellular and to use logical steering, and most phones, whether Android or iPhone, will connect to Wi-Fi. If it’s not behaving like it should, it will move to cellular.

As for whether 3GPP is doing enough to incorporate Wi-Fi into 5G, well … they have a lot of work on their hands.

“The challenge I see there is they have so much to define in the 5G spec,” and that leaves little time to get around to the Wi-Fi-specific parts of the spec. “By all means, I think we’re all recognizing the need,” but the 5G New Radio spec for unlicensed is farther down the road map, Peterson said: “I think it’s going to take a while.”

Bottom line: The industry will be talking about Wi-Fi and cellular integration for the foreseeable future, and that’s good for the management of spectrum resources. In the meantime, solutions like Passpoint are facilitating seamless and secure handoffs between cellular and Wi-Fi, and efforts need to focus on making Passpoint even more widely available at enterprises and other venues. — Monica@fiercewrlsstech

"Editor's Corners" are opinion columns written by a member of the FierceWireless editorial team. They are edited for balance and accuracy.

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