April 30, 2012

Wi-Fi 'Voice-Enterprise' Cert: No Longer Stuck On Hold

According to a Milestone Group survey, enterprise WLAN expansions are being driven to increase density and support new devices and applications such as smartphones and voice. To date, over 600 phones and 1200 smartphones have been certified by the Wi-Fi Alliance (WFA) for basic Wi-Fi interoperability.

However, succeeding at large voice-over-Wi-Fi (Vo-Fi) deployments is still no slam-dunk. Joe Epstein, author of the book Scalable VoIP Mobility: Integration and Deployment and a former chair of the WFA's Voice over Wi-Fi Technical Certification Task Group, believes that standards-based certification is needed to replace older, more custom solutions developed by disparate vendors.

"Those proprietary mechanisms definitely work when set up properly, but there is a lot for customers to have to think about and for vendors to do," he says. "The [WFA] Voice-Enterprise certification program will make it easier for everyone to get solutions right the first time."

Voice-Enterprise is a long-in-coming WFA test for interoperability among different vendors' Vo-Fi-capable products in large enterprise settings. The Alliance expects to start certifying products this summer.

Meeting Enterprise Needs

The WFA's 2008 Voice-Personal program was a solid start but did not go far enough to meet enterprise-wide requirements. According to WFA senior marketing manager Tina Hanzlik, Voice-Personal was designed for homes and small offices with a single access point (AP). "Voice-Enterprise looks at larger networks that need fast transitions between APs, admission control and enterprise security," she says.

Specifically, Voice-Enterprise builds on the WFA's Wi-Fi Multimedia (WMM), WMM Power Save and WPA2-Enterprise certification programs, adding selected capabilities from IEEE 802.11k, 802.11r and 802.11v to maintain high performance of notoriously delay-sensitive voice sessions.

  • 802.11r enables continuous connectivity by enabling fast, secure, seamless handoffs from one AP to another.
  • 802.11k improves AP discovery to stop client roaming to over-utilized APs with strong signal. Instead, APs detect when clients are moving away and help them make better choices.
  • 802.11v provides clients with topology information, increasing their network awareness in hopes of improving overall WLAN performance.
Benefits for All

Such improvements are essential for voice quality in enterprise WLANs. But Aruba Networks Fellow Partha Narasimhan expects all Wi-Fi clients to benefit.

"The ability for infrastructure and clients to exchange RF measurement information improves the quality and timing of roaming decisions. Infrastructure can [now] suggest roaming target APs to associated clients and trigger roams," explains Narasimhan. "Once a roaming decision has been made, Voice-Enterprise [can] quickly transfer security and QoS [quality of service] contexts to the new AP."

Dave Stephenson, a senior leader in Cisco's wireless networking business unit, echoed this view. "The new certification will not only improve voice quality and user experience, but also provide the critical, consistent connectivity needed in many industries," he says.

Long Time Coming

Vendors are already implementing Voice-Enterprise features; the WFA expects to start certifying products early in the third quarter. But why has Voice-Enterprise taken so long to launch?

Says Epstein: "Getting voice quality right touches so much of the network - quality of service, security and performance - [that] it's better to take the time needed to get it right."

For example, certification tests more than standards. "It measures performance with strict guidelines in a way that voice needs," says Epstein.

Like Voice-Personal, Voice-Enterprise will include metrics for latency, jitter, packet loss, plus handoff delay inside and between domains. "A network domain is what you might see in an enterprise, where you have a network composed of similar APs from the same vendor," explains Hanzlik. "We differentiate this from [handoffs] involving APs from different vendors."

Reaching the Finish Line

While goals might seem straightforward, "Voice-Enterprise [brings] together many standards and the best of several proprietary features. Making everything work well together made this a very complex program to complete," says Hanzlik.

Ultimately, success requires both infrastructure devices and client devices. "Initially, we expect certified client devices to include laptops, tablets and handsets; later we expect expansion to other mobile devices," predicts Hanzlik.

As for infrastructure, most enterprise WLAN vendors are likely to pursue certification, albeit at their own pace. Cisco was the first to support 802.11r in its Aironet 3600 Series AP in January. And Aruba has played an active role by providing equipment for the program's test bed, which means that any client device presented for certification will get tested against Aruba's gear.

According to Hanzlik, certified products will reap broad benefits. "Not only will voice users have a more seamless mobile experience, but enterprises will gain bandwidth management and power save capabilities," she says.


DECT phones provide an attractive alternative to Wi-Fi where mobile handsets are a critical need. DECT has its own infrastructure and spectrum, and is a TDM technology so QoS is a non-issue. Battery life is also quite good. The downside is that the user must carry a unique phone, so the user is likely stuck with the enterprise phone in one pocket and an iPhone in the other.

Thanks for putting Voice-Enterprise into context, Steve. VoIP over Wi-Fi is certainly just one option for mobile enterprise voice.

DECT also uses unlicensed spectrum, but it typically operates in frequency bands that create larger coverage areas and are far less congested with interferers. But, as you note, DECT handsets do not deliver converged communication like VoIP over Wi-Fi can when using a smartphone.

In addition to VoIP over Wi-Fi, another option for converged mobile enterprise voice is in-building cellular. Joanie wrote a good TechNote on the pros and cons of in-building cellular - see http://www.webtorials.com/discussions/2012/03/boosting-cellular-signals-indoors.html

It would be really interesting to know how many enterprises have already deployed or are planning to deploy each of these alternatives.

Joanie did a nice job with the cellular in-building issues. The DECT alternative is best suited to situations with a fixed geography, such as a warehouse or hospital ward, where mobile performance needs to be reliable, and where interference would be highly detrimental to safety or performance. BYOD users want acceptable coverage, no matter which carrier they happen to have. When enhanced coverage is not feasible, a fixed-mobile-convergence device and WiFi may work. However, just using a wired phone seems likely be the cheapest and simplest approach.

The Wi-Fi Alliance launched Voice-Enterprise with today's press release:


"AUSTIN, TX, May 9, 2012 - The Wi-Fi Alliance® today announced that it will soon begin to certify products for two new programs that deliver enterprise-grade voice quality, mobility, power savings and security protections.

Wi-Fi CERTIFIED™ Voice-Enterprise is designed to support good voice call quality in large enterprise networks that require support for advanced WPA2™-Enterprise security mechanisms. The program builds on the existing Wi-Fi CERTIFIED Voice-Personal program to support fast transitions between access points APs and provide management for voice applications.

Wi-Fi CERTIFIED WMM®-Admission Control provides bandwidth management tools to optimize the delivery of voice and video traffic in Wi-Fi® networks.

Planned for launch late in the second quarter, the new certification programs will provide enterprise IT managers solutions for better voice quality and bandwidth management in their Wi-Fi networks..."

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