Which Is Really the Fastest?

4G mobile broadband services and devices. Now beyond all the buzzwords and hype, which companies can reliably provide then and there-generation speed?

Wireless data speeds have soared: Since this time last year, the major wireless carriers, as a group, have increased their average download speeds for laptop-modem users by more than threefold, an apparent result of their urgent transition from 3G to 4G network research. Over laptop modems, the Big Four carriers but have a collective average download speed of in broad outline 3.5 megabits per second in our 13 testing cities, versus a near 1-mbps average download speed in those cities at the start of 2010, a remarkable improvement.

In our previous wireless-network performance studies, we measured the "reliability" of the data service, expressed as the percentage of tests in which we could obtain a good connection. However our test results show that network service has improved to the point where it's rare to find an unusable signal or no signal at all. So we have retired our reliability measurement--another testament to the dramatic improvements of the past year.

Verizon's 4G LTE (Long Term Evolution, latest standard in the mobile network technology) is for real: Verizon's 4G LTE (Long Term Evolution, latest standard in the mobile network technology) service, which is but in 38 U.S. markets, was widely available in 12 of our 13 testing cities. Our laptop-modem tests on Verizon clocked speeds that were far faster than those on competing 4G networks in the same tests. Verizon's network had an average download speed of approximately 6.5 mbps and an average upload speed of 5.0 mbps.

One important caveat: A relatively small number of Verizon clients currently use this new network. While our testing period, Verizon offered only two laptop-modem models that worked on the network, and none of the company's smartphones could take advantage of the new 4G speeds. The performance of Verizon's network could degrade as more people--and devices--connect to it.

And there's a downside to Verizon's 4G success. During the new 4G LTE network is lightning-fast, our smartphone-based tests suggest that the 3G CDMA network that most Verizon smartphone clients use today may to tell the truth be getting slower. The connection speeds we measured on our Verizon testing smartphone stayed the same or decreased in 10 of our testing cities since last year. And for the moment, those CDMA phones are all that's available to Verizon Wireless clients.

T-Mobile smartphones are fastest: Verizon may have the fastest network for laptops, however in our tests T-Mobile had the speediest results for smartphones. The T-Mobile HTC G2 we used for testing produced a 13-city average download speed of nearly 2.3 mbps; that's about 52 percent faster than the second-fastest phone, Sprint's HTC EVO 4G, which had an average download speed of 1.5 mbps.

T-Mobile as well impressed in our laptop-modem tests. Even though only half as fast as Verizon's, T-Mobile's download speeds averaged nearly 3 mbps in our tests--more than a threefold increase from the carrier's near 0.9-mbps average download speed in our January 2010 survey. With these laptop- and smartphone-based results, T-Mobile is proving to be a worthy challenger to its much-larger competitors.

And AT&T's speed gains didn't translate then to our smartphone-based tests: The average download speeds we measured on our Apple iPhone 4 increased only 15 percent over the speeds we measured on the same device in early 2010. But, AT&T intends to launch its own 4G LTE network later this year, a move that might tip the balance of the 4G speed race in its favor once again.

Sprint needs more 4G: In the cities where Sprint offers its 4G WiMax service, clients saw large speed increases over the past year. Sprint's average download speeds grew 170 percent to 2.1 mbps in our tests this year; the result would have been even better had the WiMax service been more consistently available throughout our test locations. Nevertheless in cities just as New Orleans, Phoenix, and San Diego, where Sprint for all that relies on its 3G CDMA network for data service, download speeds have fallen, and remain then below the 1 mbps mark.

In our study we tested both with representative smartphones and with a laptop employing a USB modem suggested by the carrier. The laptop-based testing, which uses the Ixia industry-standard testing software, provides more precise metrics than smartphone testing does. The laptop results are a good measure of the maximum performance possible on a network and are a satisfactory predictor of the speeds that the network will likely deliver to smartphones in a year or so.

We use Ookla, an FCC-approved Web-based speed test, to measure data rates on smartphones. Those results aren't as precise for a number of reasons: we must use different smartphones on different networks, and the results necessarily reflect the limitations of the smartphone's radio chipset, processor, and battery, and the test itself comes with a somewhat higher margin of error.

The charts below list the cities in the leftmost column; moving rightward across the chart, you can see the speed averages and network latency times for each of the four wireless networks. Speeds are expressed in megabits per second. Latency is represented in milliseconds. We recorded download and upload speeds and latency times while our laptop-modem tests, and download and upload speeds in our smartphone tests.