In my prior post, Campus 802.11n Kickballs and Basketballs, I mentioned we were having some late night fun on a site after deploying 802.11n for a K-8 school.
The Adtran Netvanta 160s that we installed support WMM/802.11e and Quality of Service (QoS) for Enterprise-class Voice over Wi-Fi. We used the opportunity to evaluate voice services on our iPhones. What we used to test: Talkatone and a Google Voice account and Voxer's WalkieTalkie, a push-to-talk iPhone app.
Our expectation was that our calls would drop, but they didn't. Instead, when our test calls were handed off from one AP to the next, the very end of the word spoken would sound "heavy" (Can you hear me now?) or it would get clipped (Can you hear me--?). The noticeable voice impairment was latency. We believe we experienced about a half of a second delay on the test calls. Audio was good.
Now, while the Adtran NV160s are not fully compliant, according to Adtran they are working towards compliance with the WiFi Alliance products.
According to the WiFi Alliance certification programs for enterprise-grade voice and mobility services:
"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.
"Wi-Fi CERTIFIED WMM-Admission Control provides bandwidth management tools to optimize the delivery of voice and video traffic in Wi-Fi networks.
These standards--802.11k, 802.11r and 802.11v--are key elements for Enterprise Voice:
* 802.11r enables continuous connectivity by enabling fast, secure, seamless handoffs between APs.
* 802.11k improves AP discovery to stop clients from roaming to over-utilized APs with strong signal. Alternatively, APs will detect when clients move away and help make better choices.
* 802.11v provides clients with topology information, increasing network awareness to improve overall WLAN performance.
The feedback I've given to manufacturers is:
* We want clients that run on smartphones and integrate to the telephony solution
* These clients need to run over our LAN WiFi (VoWiFi) because customers want to pare down PBX hardware ownership (number of devices)
* Customers want to continue to pair their desk phones to their cellphones
* We need to maintain one infrastructure, not two (i.e., WiFi and DECT)
There's also the awareness in the BYOD crowd that they have expectations, and some of them are, as we've witnessed in the past, that voice can be almost as good as we're used to, and still be acceptable. The social media tools seem to dictate a sliding scale that vacillates between desires and need; I have a desire to communicate with you but maybe a need to communicate with you via voice, immediately. That sliding scale of use is going to make future WiFi deployments interesting and challenging.
