Dan Rowinski's Mobile Platform

By Dan Rowinski

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New weapon in the 4G wars: Voice over LTE

One of the big questions for the major cellular carriers is how to integrate data speeds and voice functionality into Long Term Evolution (LTE). The architecture of the standard is transitioning from Univeral Mobile Telecommunications Systems (UMTS which itself is based on Global Systems for Mobile Communications, or GSM) to an all IP-based standard.

The IP functionality of LTE makes voice a little bit more difficult to integrate than data capabilities; it's a lingering question that AT&T and Verizon are working on.

The answer is voice over LTE, or VOLTE. Think of it like voice over IP, but over a cellular broadband network. It is fundamentally a new way to do voice on an IP system that is not integrated with Wi-Fi.

Verizon has to deal with this as a necessity because its current standard, CDMA, cannot do simultaneous voice and data the way the GSM standard can. The first 4G LTE phones rolling out also have 3G capabilities that presumably can run the voice aspect while the 4G runs the data, but that is not a long-term solution. Either 4G phones will need two LTE radios (one for voice, one for data) or carriers will have to figure out how to split VOLTE and data subsets.

Verizon is seemingly the first to figure this out, and it demonstrated a VOLTE phone call at the Mobile World Congress in Barcelona, Spain.

In other 4G news, it looks like Sprint may dump its WiMax standard and go with LTE, according to an Engadget report from MWC. Sprint could keep the WiMax standard and consolidate with LTE, as it does not look like it would be difficult for the company to upgrade its base stations to function with both WiMax and LTE. Or it could just straight make the switch from one standard to the other.

That would bring three out of the four major U.S. cellular carriers to using LTE as its primary 4G network. In the annals of history, even though it was touted as the first ā€œ4Gā€ network, WiMax may go down as more of a ā€œ3.33Gā€ standard, as LTE and high-speed packet access make advances. Where does that leave Clearwire, which owns most of the WiMax bandwidth? In trouble, probably.

Speaking of HSPA, T-Mobile seems to feel pretty confident in it these days and it appears that HSPA can scale better than developers previously thought. Ericsson, which owns a great deal of cellular bandwidth, clocked HSPA+ at 156 megabits/sec downlink in Stockholm, Sweden, earlier this month. That is also good news for AT&T, since it has rolled out HSPA+ with theoretical downlink speeds of 56 megabits/sec to 80 percent of its network.


Posted by Dan Rowinski on Feb 18, 2011 at 12:19 PM


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