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,
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.
Sprint's SmartView software shows the network's signal strength with vertical bars. The modem can switch between 3G and 4G service in a few seconds, but only if you tell it to -- there's no automatic switching. There are some mobile creature comforts, such as online coverage maps, GPS (which works only with a 3G connection) and something called the Digital Lounge for downloading apps, music and games.
Unlike most other USB modems, the 250U has jacks to connect an external antenna for better reception. Sierra Wireless says its $35 Band Blade Antenna, for example, can boost the signal by up to 50% and works with both 3G and 4G networks. (I didn't test an external antenna for this story.)
The final pieces of the 4G puzzle are the service plans that Sprint offers. I used the $60 4G/3G Mobile Broadband Connection Plan, which includes unlimited use of 4G data but limits 3G usage to 5GB per month. In one of the few high-tech bargains available today, it costs the same as Sprint's 5GB-per-month 3G-only plan.
Sprint also sells a $50-per-month 4G-only plan, but with that option you lose the 3G safety net. Infrequent travelers can pay $10 for 24 hours of unlimited 4G service.
To gauge Sprint's 4G network, I tested it in and around New York City, where commercial service started in early November. First, the good news: It's fast. Really fast.
The 4G network delivered an average download speed of 4.1Mbit/sec. -- about what you'll get with a wired DSL or cable modem connection. It was seven times faster than Sprint's 3G service, which averaged 550Kbit/sec. I received a peak 4G download speed of 11.2Mbit/sec. at one location, nearly 10 times faster than the 1.2Mbit/sec. of throughput available on Sprint's 3G network at the same location two minutes later.
In other words, forget about having to go to Starbucks or a public library to download that huge file you need.
Now for the bad news: I found uploading data painfully slow on both services. While 3G mustered a 25Kbit/sec. throughput from notebook to server, 4G was able to move 41Kbit/sec. -- not a terribly significant improvement. Clearly, this service is more useful for downloading large chunks of data, such as monster spreadsheets, videos and presentations, than for tasks such as uploading content to a Web site or sending e-mails bulging with attachments.
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.
Price: Sprint 4G/3G Mobile Broadband Connection Plan is $60 per month for unlimited 4G service plus 5GB of 3G service; Sierra Wireless AirCard 250U 3G/4G USB Modem is free with two-year Sprint contract and mail-in rebate, $250 separately
Pros: Easy installation, high-speed 4G service, 3G or 4G connections, simple interface, modem swivels for better reception
Cons: Limited scope of 4G network, high power consumption
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.
This story, "3G v. 4G: Real-world Speed Tests" was originally published by Computerworld.