Mobile workers who need always-on Internet access -- and who don't want to rely on public Wi-Fi hot spots -- often turn to a cellular network for connectivity, using either a 3G-equipped notebook or an external 3G modem. Now carriers are touting faster fourth-generation wireless networks as the next phase of mobile computing. But to make use of the new networks, you have to buy a 4G-capable device or modem and a new, often more-expensive service plan.
Is it worth the hassle and expense of upgrading to 4G? To answer that question, I pitted Sprint's WiMax service -- the first 4G service available in the New York metropolitan area, where I live -- against its 3G network in a series of real-world tests (see "How I tested").
Sprint 4G: What you need
As is the case with any wireless service, you need three things to get access: a network, a device for connecting and a service plan. Available in 62 cities, from Everett, Wash., to Tampa, Fla., Sprint's WiMax wireless service in the U.S. is known as Clear and is operated by Clearwire; it's based on the IEEE 802.16e specification. The network provides adequate coverage on the coasts (see map), but it's hit or miss in the middle of the country, and there are 12 states with no Sprint 4G service at all.
When you can't get a 4G connection, the fallback is to use Sprint's 3G network, which is based on EV-DO (Evolution Data Optimized) technology. It's available in all 50 states, although -- as is the case with other 3G networks -- there are huge holes in the upper Midwest. Sprint says that over the next two years, it will fill out a national 4G network.
In contrast, T-Mobile currently offers an upgraded High Speed Packet Access (HSPA+) 3G network. AT&T is also busy rolling out HSPA+ and is testing LTE (Long Term Evolution) technology for a planned commercial 4G rollout over the next two years.
Meanwhile, Verizon has just launched its own LTE network on a trial basis with limited coverage in 38 cities and 60 airports. The company says the network will be complete nationwide in 2013. Although it's not available in my suburb, Verizon LTE has been rolled out to some parts of the New York metro area, and I hope to test it in multiple locations soon.
The second part of the 4G puzzle is the connection device. The Sierra Wireless AirCard 250U modem that I used for testing weighs just 1.9 oz., connects to a laptop via a USB port, and can be folded up to less than an inch thick when not in use. The disk-shaped receiver, which measures about 2 in. across, can rotate and swivel up and down to get better reception. The device has a list price of $250, but it's free with a two-year Sprint contract.
The 250U works with systems running Windows 7, Vista or XP, or Mac OS X 10.5 or 10.6. Setting up the 250U on my Lenovo ThinkPad W510 with Windows 7 took about 10 minutes; it connected to the network on the first try.
How I tested
To see how Sprint's 3G and 4G networks compare, I used a Sierra Wireless AirCard 250U modem that works with both the 3G EV-DO and 4G WiMax networks. At 10 locations in New York and New Jersey, I fired up my ThinkPad W510 and connected to the 4G network. After noting the signal strength of the connection, I used Ookla's Speedtest.net utility to measure latency and download and upload speeds. Finally, I watched an online HD video and listened to an Internet radio station.
I measured each result three times and then repeated the tests with the 3G network. I returned to each location at three different times over a 10-day period and repeated all the tests on both 3G and 4G networks. I also used 3G and 4G connections on a moving commuter train and as a passenger in a car and averaged all the results together.
To see how connecting with the modem over 3G or 4G affects battery life, I ran some tests back at my lab. To get a baseline measurement, I connected the fully charged ThinkPad W510 to my home Wi-Fi network, set it to play an Internet radio station continuously and timed how long the system's battery ran for. I then repeated this test three times with the charged computer connected to the 3G network and three times connected to the 4G network.