Feature Article

March 28, 2016

New 'MulteFire' Lights up Unlicensed LTE Models

Faced with the scarcity, cost and difficult propagation characteristics of the remaining greenfield licensed spectrum, one of the first steps in achieving a next-gen wireless network vision that can stand up to the growing thirst for rich content will likely be the use of unlicensed LTE approaches. This would allow operator access in the 5GHz band currently reserved for public safety and Wi-Fi applications. There are plenty of approaches to it, but one of the most innovative is what’s known as MulteFire.

“Our reliance on wireless connectivity to deliver rich content to our ever-growing number of devices continues to put a severe strain on the resource that delivers it—network capacity. And the trend is astounding. In fact, the industry is preparing for a 1000x increase in mobile data traffic,” explained Qualcomm, in a next-gen networking brief.

As operators prepare for the next generation of wireless networks, it’s expected that multiple interfaces, including LTE, small cells, and Wi-Fi and other unlicensed spectrum technologies, will all play a role in what will be one big unified HetNet, or heterogeneous network.

“Network operators are working to densify their networks—deploying more small cells in licensed spectrum, which ensures a predictable performance (thanks to its exclusive use),” Qualcomm said. “But to reach 1000x, we must opportunistically use capacity in unlicensed spectrum—such as 5 GHz—as well.”

MulteFire Goes Its Own Way

MulteFire is a departure from other unlicensed LTE approaches (like LAA and LWA, both standards that are expected to be ratified this summer), because it involves using LTE in unlicensed bands without the need for licensed “anchor” spectrum of any kind.

MulteFire will accomplish this by combining the performance benefits of LTE technology (enhanced capacity, range, mobility and quality-of-experience) with the simplicity of Wi-Fi-like deployments. MulteFire will use the signals and channelization of the robust LTE radio link, while also leveraging evolving LTE technologies for self-organizing small cells suited for hyper-dense deployments.

It’s an approach that’s championed by a group of heavy hitters that make up the recently formed MulteFire Alliance: Athonet, Baicells, Boingo Wireless, Casa Systems, Ruckus Wireless and SpiderCloud Wireless have all joined board-level members Ericsson, Intel, Nokia and Qualcomm.

New Entrants, New Business Models

For wireless operators, MulteFire can be used in shopping malls, stadiums and other places where they would otherwise install expensive distributed antennae systems (DAS) to provide coverage and capacity not afforded by their macro networks. But it also clears a path forward for cable operators and other wireline ISPs to get a piece of the wireless market without needing extensive, expensive licensed spectrum holdings.

In fact, because it relies solely upon unlicensed spectrum, small, medium and large enterprises, as well as venue owners, can all get a piece of the action, too.

“This is disruptive in the sense that it widens the amount of parties that could build a higher quality network,” noted Stephan Litjens, MulteFire Alliance board chair and head of Innovation Steering at Nokia, in an interview. “We are hoping our efforts will spur some innovation. Typically, what happens when the barrier to enter is lower, more people try things out and innovate.”

Cable MSOs and others could use MulteFire as a path to creating their own large-scale networks, with the aim of either providing add-on retail service to the triple play or for business customers, or, becoming neutral host providers. That neutral wholesale environment can augment wireless network operator environments by providing enterprise penetration, and spawn a new kind of MVNO opportunity. Because MulteFire is a variant of LTE, synching up for roaming agreements presents limited technical obstacles.

“The entities taking advantage of this would be MVNOs and those interested in extending an operator’s service, so users would need to connect back to their own operators’ core at some point, and it would have a roaming or MVNO structure to it,” explained Ed Gubbins, a research analyst for Current Analysis, in an interview. “It’s an open question as to how mobile operators will feel about this. Operators in the U.S. are not wild about the idea of providing a service without being able to control that service. But, operators have been struggling for a long while to penetrate these enterprises so they may weigh that in favor of the idea.” 

An interesting point to note is that MulteFire also expects to replicate the economics, scale and deployment characteristics of another unlicensed technology: Wi-Fi. Like Wi-Fi, the goal for MulteFire devices is to be able to work on any standard MulteFire network, anywhere in the world (in the global 5GHz band), thus allowing for commercial off-the-shelf gear to be sold.

“There’s even talk of not needing SIM authentication; it implies that small cells could be deployed without an operator’s spectrum needing to be involved,” said Gubbins. “That poses the potential for enterprises or hotels deploying their own LTE small cells.”

And that in turn opens the door to using existing enterprise channels and integrators to build these things out—further sparking a mass-market type of scaling, in theory.

Gubbins added, “If enterprises are doing this, it could lower the economics of small cells and devices and further encourage the market. Anything can happen—we don’t know where this is going to go.”

Bringing it back to traditional stakeholders, this is also a boon for operators, because using existing enterprise channels for MulteFire would reduce the complexity of small-cell deployment. “For the wireless operators, it’s a challenge to manage license spectrum holdings,” said Litjens. “You have to have co-channel network planning for small cells—so designing and implementing licensed networks takes a unique skill level. Not so with MulteFire and unlicensed.”

He added, “From an installation and service and network planning perspective, there is a big benefit in leveraging the Wi-Fi installer base. The Wi-Fi community has done a great job to make deployments more streamlined, and they will be able to reduce the barriers for operators to move into small cells.”

What’s Next

As for market development, the MulteFire Alliance has a speedy roadmap in mind.

While the group is outside of the 3GPP LTE and 5G development umbrella, it’s not ignoring the standards: It’s developing the MulteFire specification based on 3GPP Release 13 and Release 14 advancements, including specifying using the downlink and uplink in unlicensed spectrum. The Alliance has set up a standardization forum and certification program, and expects to have the first lab trials underway by the end of the year.

The first field tests and commercial trials are expected in the first part of 2017.

“Vendors and operators have poured billions of research money into LTE, and most of that you can re-use in MulteFire,” said Litjens. “This allows a more aggressive timeline that one would typically expect from new technology.” 




Edited by Rory J. Thompson


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