VoLTE: Progress and problems

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Voice over LTE has been one of the most highly anticipated network features to come along in recent years. As it stands, LTE is only used for data services, with voice being routed over legacy circuit-switched networks.The ability to offer voice over IP service via wireless offers operators a path toward a flatter, less expensive and more efficient network, with the ability to eventually sunset their 3G networks.

Operators have been talking about VoLTE for several years now, with expectations that roll-outs would begin last year in earnest — only they’ve been delayed again and again as carriers grapple with the real-world performance of VoLTE not being up to the quality expectations set by 3G networks.

At last week’s LTE Innovation Summit in Del Mar, Calif., it was clear that VoLTE is still coming together, and many pieces that have to work together in order to make this radical jump in technology.

In a technical track session, Rob Wattenburg, SwissQual product sales manager, played recorded good and bad CDMA and VoLTE calls from the field. The good VoLTE call had excellent audio quality, markedly better than the CDMA calls even at their best. But even minimal, temporary packet loss in a VoLTE call caused words to drop out mid-sentence, making it obvious why the technology is not yet in prime-time and the very small margins for error that operators are dealing with.

On the bright side, though, Wattenburg made note of the fact that VoLTE devices are widely available to wireless engineers for testing in order to advance the technology – in fact, he floated the idea that getting functional devices into the field for wider testing before they are launched, as is being done with VoLTE now, may be a way for the wireless industry to cut the overall amount of testing needed for successful deployment of new devices. The Global Mobile Suppliers Association’s most recent report said that there are nearly 60 commercially available VoLTE-capable devices globally, and Rohde & Schwarz certainly had no shortage of devices from major U.S. carriers to use in its demos for VoLTE testing.

Call audio quality isn’t the only issue. Peter Seidenberg, managing director of P3 Communications, spoke of the bench marking that his company has been doing with major operators worldwide who are trying to roll out VoLTE. The news is not encouraging. Call set-up times for VoLTE can run from mediocre to completely unacceptable – Seidenberg said that in some networks, VoLTE calls can take as long as 30 seconds to connect.

“If you don’t solve this problem, forget about the innovation in LTE — your customers will run away,” Seidenberg said. He also noted that switching the device between 2G, 3G and LTE networks can also lead to an unacceptable amount of time that a phone is unable to be reached. It may only be five to 10 seconds at a time that a device is unable to be called, Seidenberg said, and the industry might be tempted to write off that small amount of time. But, he said, those network switches are likely to be happening many times per day since LTE is not yet ubiquitous, and should not be underestimated.

Many of the issues can be reduced or solved by proper configuration, he noted, but “‘it’s really hard work.”

“LTE is just a capacity technology” as most operators are currently using it, Seidenberg said — meant to deal with the data crunch while operators maintain voice coverage on their 3G networks. LTE services do have promise, he added, but “it is a bumpy road to get there.”

Doug Makishima of D2 Technologies also pointed out another degree of the connection complexity, speaking on VoLTE as well as the rich communications suite services that hold potential for operators to recapture some of the messaging and presence engagement that has been dominated by over-the-top players. He spoke of the desire for a “green button” experience – i.e., a user hits the green call button and everything works. However, he also noted that phones have more than one native dialer – a user can place calls from the main phone dialer, as well as directly from their address book. They can also place calls from applications, such as mapping or navigation apps, that operators and device manufacturers have limited control over, but that need to be able to connect a VoLTE call in a timely and seamless manner before the feature can be widely launched.

The interface that Makishima displayed for RCS (which has been launched in limited areas as Joyn), showed the power of integration and it was obvious why RCS holds appeal for operators. The user interface for calls had additional buttons to allow users to choose between starting a traditional call or a video call, as well as presence indicators for contacts in the address book and the ability to directly send SMS or files – very sleek, well-integrated and designed to make carrier services the most convenient to access in order to trump OTT apps for the same features.

For videos from the LTE Innovation Summit, check out our YouTube channel.

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About Author

Kelly Hill

Editor, Big Data, Analytics, Test & Measurement
[email protected]
Kelly Hill currently reports on network test and measurement, as well as the use of big data and analytics. She first covered the wireless industry for RCR Wireless News in 2005, focusing on carriers and mobile virtual network operators, then took a few years’ hiatus and returned to RCR Wireless News to write about heterogeneous networks and network infrastructure. Kelly is an Ohio native with a masters degree in journalism from the University of California, Berkeley, where she focused on science writing and multimedia. She has written for the San Francisco Chronicle, The Oregonian and The Canton Repository. Follow her on Twitter: @khillrcr

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