Verizon Wireless is not yet sure which path to take to 4G.
One thing's for sure, Ultra Mobile Broadband (UMB) is not a slam dunk.
UMB is the CDMA2000 path to 4G, the next-generation IP-based wireless technology capable of 100Mbps to 1Gbps of throughput, with quality-of-service and security. UMB is also known as CDMA2000 EV-DO Revision C (Rev. C).
Other 4G technologies are Long Term Evolution (LTE), being hammered out by the GSM/UMTS world, and WiMAX, which is defined by the IEEE.
Verizon Wireless' network is based on CDMA2000 EV-DO Revision 0 (Rev. 0) and Revision A (Rev. A), which means it logically should follow the UMB path. But it's not that easy.
After all, Sprint Nextel operates a Rev. 0 and Rev. A network and it went with WiMAX.
"I think a lot of people made the assumption, well you just do Rev C," said Kyle Malady, vice president of network technology development at Verizon Wireless, at this week's CTIA Wireless 2007 conference. "But we're not looking at it like that. We have a host of opportunities here."
After acquiring Advanced Wireless Services spectrum in last year's auction, Verizon Wireless had to start thinking of its 4G strategy. The operator is trialing all three 4G technologies, examining throughput, spectral efficiency, and evaluating the business case of all three: is there an ecosystem of chipset developers and device manufacturers that Verizon Wireless can tap to quickly bring products and service to market?
"There'll be a lot of vetting and we'll pick something," Malady says. "Right now we're just in real deep study about what we want to do."
Though Verizon Wireless is unsure about which flavor of 4G to go with, it is sure about one thing: it needs a Frequency Division Duplexing (FDD) implementation.
FDD, which is used in most 2G and 3G networks, uses paired frequencies to transmit data. The alternative, Time Division Duplex (TDD), uses one.
The current version of WiMAX is TDD -- that's one of the reasons Sprint Nextel chose it. But the IEEE is working on an FDD version as well, Malady says.
"I don't have any TDD spectrum," Malady says. "We're just looking at the technology right now and we're working with folks who are inside that ecosystem figuring out what we can do, what we can trial, when an FDD prototype might be available."
The problem is, the FDD requirement does not rule out LTE or UMB either. LTE works in both modes, and UMB operates as FDD.
Another certainty is that Verizon Wireless will take its time in making its 4G choice despite Sprint Nextel's claim that it will be at least two years ahead of competitors with WiMAX.
"We're not going to be forced by time on this," Malady says. "We want to make sure we vetted the full array of issues before us and we just want to make the right decision."
In the meantime, Malady says, "We're going to be riding the Rev. A horse for a long, long, long time."
Verizon Wireless has upgraded more than 135 million PoPs with Rev. A to date and will have 200 million PoPs covered by year end. Upcoming service enhancements to the Rev. A network will include push-to-talk -- or push-to-x -- and mobile VOIP.
The carrier plans to begin Rev. A push-to-x trials late this year. Mobile VOIP will follow that.
This will be Verizon Wireless' second pass at push-to-talk. The operator's first attempt on its CDMA 1xRTT network four years ago fell flat.
"It wasn't very popular, it didn't gain a lot of traction," Malady acknowledges. "It was very much a niche product. We put it out there, we had some foibles. But we fixed those. We haven't really marketed it heavily."
But adding more features in the push-to-x game and delivering it over a higher performance network might be the trick.
"If you believe in the push-to-x concept and you can do that over the Rev. A network, I do believe there's a market there," Malady says. "Tying in presence with it, it shines up that whole segment and I think there'll be another area to explore there."
This story, "Verizon Wireless Crawls to 4G" was originally published by Network World.