The two networks had comparable latency times of 118 milliseconds and 112ms for 3G and 4G, respectively. (Latency measures how long it takes in milliseconds for a data packet to travel over the Internet from your computer to a central server and back again.) That response is about 10 times slower than most wired or Wi-Fi network connections, which typically have a latency of about 10ms.
This delay is often a frustrating factor in cell-network data connections. A high latency can slow an otherwise fast network to a crawl, for instance, and streaming video can end up looking jerky. However, the speed of Sprint's 4G network seems to have offset the latency problem: I found that streaming videos played reliably over the 4G connections, while the same clips fluttered and froze with some 3G connections.
More bad news: The 250U modem is a power hog. Over Wi-Fi, the ThinkPad W510's battery life averaged 3 hours and 10 minutes, but when I connected to the Internet with the 250U modem, the battery lasted just 2 hours and 8 minutes for 3G use and 1 hour and 59 minutes for 4G use. (On the plus side, using 4G didn't consume that much more power than using 3G.)
Using 4G can feel like a breath of fresh air for mobile workers who are accustomed to waiting and waiting for Web pages to load and files to appear. With a wide pipe of wireless data available for videoconferencing or downloading huge spreadsheets and media-heavy presentations, 4G service has the power to rewrite the way business is conducted on the go.
Sprint's WiMax network can change the way you think about mobile data, from "hurry up and wait" to "done!" Early tests indicate that Verizon's LTE has great potential too, although it's too soon to say for certain how it will perform in heavy, real-world use, and there are still a few kinks to be worked out. I just wish 4G service were available in more places, but that's just a matter of time.
My advice? Get on the 4G bandwagon as soon as it comes to your area -- you won't regret it.
Brian Nadel is a freelance writer based near New York and is the former editor in chief of Mobile Computing & Communications magazine.
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This story, "3G vs. 4G: Real-world Speed Tests" was originally published by Computerworld.