Most people don't have multiple WiMAX devices sitting around for speed test comparisons, so it's no surprise that the biggest complaint we've seen relates to poor signal reception, rather than data speed specifically. Forum posters (both on Sprint Community and the Google Mobile Help Forum) reported excellent reception at home but poor or no reception at work, even when colleagues with other Sprint devices were able to make and receive calls in the same office. In New York City, we didn't have any issues making and receiving phone calls, or accessing data in any of our test locations, but we did notice signal strength discrepancies between the Nexus S 4G and Epic 4G. By the window in our office, for example, the Nexus S 4G registered a signal strength of -86 decibel milliwatts (dBm), and two signal bars (out of four), while the Epic 4G registered -65 dBm, and six signal bars (out of six), so there is definitely a discrepancy. We even tried removing the Nexus back plate, just in case the built-in NFC antenna was interfering with reception, but signal strength remained at -86 dBm.
We also tried testing in Miami, but were unable to connect to 4G from our hotel in Miami Beach, and weren't able to pick up a consistent signal in downtown Miami, where coverage maps indicate a healthy blanket of WiMAX. Because both phones suffered from poor reception, we can't isolate this specific connectivity issue to the Nexus S 4G.
We conducted 20 consecutive speed tests with both smartphones in each of five different locations -- four 4G tests in New York City, and one 3G test in Miami, as 4G wasn't consistently available. When we averaged the results, the Epic 4G outperformed the Nexus S 4G on every download speed test, even doubling transfer speeds in some cases. Upload speeds between the two devices were generally identical, with the exception of the test from the center of our NYC office. At this location, the Epic 4G offered a 72 percent boost on upload speeds. We tested a different Nexus S 4G handset in San Francisco, comparing results with a WiMAX MiFi, since we didn't have another WiMAX phone on hand. Both devices yielded comparable results in that city, which brings us to conclude either that only some Nexus devices are defective, or that all are defective, but function normally with select WiMAX transmitters.
NYC Window Speed Test
We noticed the greatest difference in download speeds when testing near a window on the fourth floor of our NYC office. When alternating between devices for 20 consecutive tests, the Nexus S averaged 2,719kbps, while the Epic 4G's average download speed was 120 percent faster, clocking in at 5,994kbps. Upload speeds were consistent between the two devices, with the Nexus S averaging 990kbps and the Epic 4G delivering 1,001kbps.
NYC Office Speed Test
Moving to a desk in the center of the office, about 100 feet from the nearest window, the Nexus S averaged 3,049kbps down, compared to 4,699kbps with the Epic -- a 54 percent boost. Upload speeds were significantly lower here than by the window, with the Nexus S averaging just 266kbps, compared to 459kbps on the Epic 4G -- a difference of 72 percent.
NYC Park Speed Test
Naturally, both phones offered the best performance outside, with the Nexus S averaging 4,248kbps down in Union Square Park, compared to 6,178kbps with the Epic 4G -- a difference of 45 percent. Upload speeds were nearly identical, as they were near the window: the Nexus S averaged 979kbps, while the Epic averaged 993kbps.
NYC Roof Speed Test
We also tested both phones from a residential rooftop two blocks from the World Trade Center, where we generally experience excellent signal reception. Again, the Epic bested the Nexus by 43 percent, averaging 4,496kbps to the Nexus's 3,146kbps. Upload speeds were consistent -- 976kbps on the Epic and 917 on the Nexus.
Miami 3G Speed Test
You don't have to travel far from New York to find another WiMAX city, but Miami's coverage map looked just as promising as the weather forecast, so both phones came along for a weekend trip to the Sunshine State. We were disappointed to find that Sprint's coverage map doesn't match WiMAX availability, however, and left without capturing a single usable 4G speed test result. 3G access was also hard to come by in parts of Miami Beach, but we didn't have trouble locking on to a signal in downtown Miami. Even on 3G, the Epic 4G offered epically superior performance, averaging 1,121kbps down -- a 92 percent boost over the Nexus's 584kbps average download speed. The Epic performed marginally better than the Nexus on the upload test, scoring 428kbps and 388kbps, respectively.
With the Epic 4G besting the Nexus S 4G on all five of our speed tests, it's easy to conclude that the newer device suffers from some significant network performance issues. We reached out to Sprint when we first looked into the problem early last week, and the carrier and Google have both confirmed that they're investigating the problem. A Sprint representative added:
That said, the Nexus S 4G's speeds are still commendable for a WiMAX device, falling within the carrier's range of advertised performance (3 to 6Mbps). But if having the best-performing smartphone is a priority, then you'll clearly want to give Sprint and Samsung some room to work out the kinks before locking yourself into a two-year contract with the Nexus S 4G.
"Nexus S 4G is one of our best selling devices. Most of these customers are very happy with their experience with the device. We are aware of the connectivity reports being brought forward by a small number of Nexus 4G customers. Google, Sprint and Samsung are examining these reports and though we have not yet been able to identify any specific causes, we are working to determine exactly what our customers are experiencing."
Myriam Joire contributed to this report.