VOIP Over Wide-Area Wireless: A Tricky Proposition

3:45 PM -- For those of you thinking of running VOIP over wide-area broadband wireless services (e.g., EV-DO, HSDPA), here are some things to think about. In the first place, if you read the fine print of the service contract, you likely are not allowed to do so. But secondly, you may not be happy with the results. If you’ve tried it and it worked, then you were lucky, and were probably running on a relatively unloaded network. I got quite a bit of insight into this topic last week listening to an engineering presentation from Qualcomm Inc. (Nasdaq: QCOM) on how VOIP will be implemented for Revision A of EVDO. The presentation was part of a PCCA meeting I chaired last week on the topic of Internet Multimedia Subsystem (IMS).

Sprint Corp. (NYSE: S) and Verizon Wireless will be deploying EVDO Rev A in the 2007 time frame. Rev A primarily features a faster uplink, but it also includes provisions such as QOS that will enable VOIP. However, that doesn’t mean that the operators will roll out VOIP right away. That will take another year or two as there are a lot of additional items required to make VOIP work.

What Qualcomm aptly showed was that to deliver high-quality, low-latency voice in IP at the equivalent (or slightly higher) spectral efficiency of current circuit-switched approaches is going to require extremely sophisticated communications protocols and voice processing. First there is packet header compression, as otherwise you’re sending 20 bytes of IP header information for every 22 bytes of VOIP payload. Robust Header compression knocks this down to 4 bytes. Then there is the elimination of PPP framing overhead, QOS implementation, de-jitter mechanisms, and items called smart blanking and time warping to recover from low-level bit loss.

Qualcomm and other vendors are actively working on these areas. Until all these capabilities are baked into the broadband wireless technology itself, any VOIP usage will be of significantly lower quality, and will consume far more bandwidth than existing voice services. Similar efforts will be required to make VOIP a reality for technologies such as UMTS and WiMax. It’s going to be the end of the decade before you see widespread VOIP over wide-area wireless networks.

— Peter Rysavy is President of Rysavy Research . Special to Unstrung

COMMENTS Add Comment
lrmobile_mmorrison 12/5/2012 | 3:52:56 AM
re: VOIP Over Wide-Area Wireless: A Tricky Proposition It must be the end of the decade already, because here in New Zealand, we have commercial VoIP service over UMTS TD-CDMA IPWireless gear with Woosh!
AllKindsOfThings 12/5/2012 | 3:52:38 AM
re: VOIP Over Wide-Area Wireless: A Tricky Proposition Thats Interesting. Do you have any indication how "full" the Woosh Network is?

Quality degradation only becomes really visible when enough people compete on bandwidth, so it might remain to be seen how well it will work when enough people are using it in parallel for VoIP Voice Calls...

Obviously Woosh is using licensed spectrum, running foremost as a Wireless Bradband play.

Its true that this can be done in principle anywhere, but that statement is still quite different from the question if installing a current VoIP client on your Device is making the same good use of the existing radio capacity than 3G (Any operator supporting Skype ove Air in its current PC Version would be plain stupid).

It would be intersting to see why anyone if he had to pay for spektrum blasts his frequencies with an inefficient way to do Voice Service, when there is a more spektrum efficent voice choice already is thre, and works well - maybe they see some service managament aspects by avoiding to deal with handset manufactures.

Seemingly current offers allow to call from computers connected by Woosh PCCard/Woosh Wireless Modem only (and of course are they the only ISP they yould allow on their spectrum - a quality advantage that WiFi always has a hard time to overcome).



Certainly they at this time are catering towards a hightech-affine customer gruop like yourself.

Another aspect is that they might in need to be push extra traffic to refinance their underused rolled out network; as the deployment is easy for end customers they will at least have a good advantage whereever the incumbent carrier is too slow in rolling out wired broadband (a model also used for example by T-Mobile in the Czech Republic).

And of course, some reason might be to be simply ignoring the deficiency because their marketing guys see it as a way to break into the market by riding the VoIP wave :-)
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