According to Jude, the ability for AT&T and T-Mobile to simply transition from one level of GSM network to another gives them an edge over the Clearwire WiMAX network, which will have to be backward compatible with Sprint's legacy CDMA technology. Jude also says that AT&T and T-Mobile also will have a slight leg up on Verizon, which will have to make the transition from CDMA to GSM for LTE.

And since it will take a long time to build and deploy LTE networks with nationwide coverage, says Forrester analyst Charles Golvin, it will be crucial that LTE users be able to seamlessly switch back to HSPA technology if they find themselves out of range of the 4G network. And since LTE will have the support of a large number of carriers that use the GSM standard, LTE users will be able to take advantage of trans-carrier agreements that could lessen their monthly roaming charges.

"That ability to hand off service is very important in today's environment," says Golvin. "We have an expectation in ubiquity in service."

How will LTE stack up against WiMAX?

Before making any comparisons between LTE and WiMAX, says Golvin, it's important to note a key distinction: WiMAX is able to deliver high-speed data today, while LTE is not. Thus, it's difficult to compare a technology that is already up and running with a technology that is still in the standards process.

Additionally, notes Gartner analyst Phil Redman, LTE shouldn't be compared to WiMAX in its current incarnation. In all likelihood, he says, LTE will be deployed at around the time that WiMAX has upgraded to the 802.16m standard, which is expected to deliver download speeds of 100Mbps for mobile applications. From this perspective, LTE and WiMAX stack up very well against one another, since LTE is also expected to deliver peak download speeds of 100Mbps.

The big issue, then, might not be which technology delivers faster data speeds but which one is most widely available. In terms of having more carriers to work with, LTE is clearly well ahead of WiMAX in the United States. Additionally, LTE currently has an advantage over WiMAX in that it's designed to be compatible with both Time Division Duplex (TDD) and Frequency Division Duplex (FDD), the two main legacy techniques for dividing downlink and uplink communication channels on the same transmission platform. WiMAX, on the other hand, is only compatible with TDD so far.

Why is this important? Because, notes Golvin, LTE will have more spectrum at its disposal using both TDD and FDD than WiMAX will have with TDD alone. While TDD sends uplink and downlink data transfers through one single channel over unpaired spectrum, FDD gives uplink and downlink data transfers through two separate channels over paired spectrum.

This is crucial, notes Golvin, because many valuable spectrum licenses, such as most of those recently sold off in the 700MHz auction, are paired spectrum licenses that are only compatible with FDD. According to reports published earlier this year, the WiMAX Forum is quietly working on a profile for mobile WiMAX that incorporates FDD, although the group has so far been mum on when it expects this profile to be completed.

Even so, says Jude, WiMAX has at least a two-year time-to-market advantage in which it will be virtually alone in the 4G market. If the recently formed Clearwire coalition is successful at locking customers into high-speed mobile broadband contracts, and if WiMAX can expand the range of spectrum it's available on, Jude says it could get a good head start before LTE comes along in 2010.

"WiMAX may find a niche in rural areas because it allows people to work extreme distances from cell sites," he says. "But ultimately, it's all about the footprint. The challenge for Sprint and Clearwire is whether they can get into a substantial number of big markets quickly enough to lock in subscribers."