Let's start with overall 3G coverage, where Verizon uses a CDMA-based EV-DO Rev. A network and AT&T uses a GSM-based HSPA network. As you probably know through Verizon's gleeful pummeling of AT&T with its "There's a Map for That" ads, AT&T's 3G network covers far less area than Verizon's.
But there are more factors to be taken into account than simple scope of coverage. When it comes to average data speeds, a recent Root Wireless study found that AT&T had higher average 3G data speeds than Verizon in Chicago, Dallas, Los Angeles, New York, Seattle, San Francisco and Washington, D.C. Overall, AT&T's average 3G data speeds ranged from a low of 246Kbps in New York and a high of 428Kbps in Dallas. Verizon, meanwhile, had average 3G speeds ranging from 195Kbps in Seattle to 259Kbps in Chicago. The study also found that both carriers had comparably low rates of 3G connectivity failure, as each carrier's connection failure averaged between 1% and 3% for all seven cities.
What would make the decision to offer the tablet on both of the big U.S. carriers' networks good is that it will give users the ability to get a real (no pun intended) apples-to-apples comparison on the quality of their 3G networks. Thus, if Verizon winds up having superior overall 3G service with the tablet, AT&T won't be able to blame the iPhone solely for overloading its HSPA network. Similarly, if the added network traffic from the tablet strains Verizon's 3G network and leaves AT&T with stronger overall coverage, it would boost AT&T's claims to have a faster, albeit smaller, 3G network.
Not just 3G
Of course, 3G networks aren't the only ways to connect wirelessly to the Internet. There's also the issue of Wi-Fi hotspots, where AT&T has an estimated 24,000 hotspots nationwide compared to Verizon's estimated 10,000. AT&T has put a big emphasis on its Wi-Fi footprint after the company expanded its Wi-Fi services to more than 7,000 Starbucks locations nationwide and after it acquired Wayport, a network and applications management company that provides back-office management for Wi-Fi hot spots.
Looking beyond current 3G wireless technology to future 4G wireless technology, both AT&T and Verizon have decided to use the GSM-based Long Term Evolution (LTE) standard as their technology of choice. Verizon is planning to launch its LTE services commercially in 25 to 30 U.S. markets in 2010; AT&T will soon follow up with commercial LTE launches in 2011 and beyond. Although there will be a limited number of LTE devices on the market at first since voice and SMS standards have not yet been finalized for LTE, Apple could still theoretically release an LTE-based tablet next year since it would be used primarily for data.
This story, "Apple Tablet Carrier Smackdown" was originally published by Network World.