Sprint XOHM (Mobile WiMAX) Review

Sprint XOHM (Mobile WiMAX) Review

by Sascha Segan

When it's good, Sprint's XOHM WiMAX network is very, very good—as speedy as a fast cable Internet connection. When it's bad, it's still pretty good. XOHM is supposed to usher in a new era of high-speed, Internet-connected everything. Based on the WiMAX 802.16e standard, which is heavily backed by Intel, XOHM should be compatible with WiMAX laptops, handheld devices, and even digital cameras and home security systems, somewhere down the road.

For now, Sprint is simply aiming at existing ISPs. The carrier is pushing XOHM as an alternative to cellular Internet for laptops, and as a possible substitute for cable or DSL broadband for home users. This technology has the potential to shake up the ISP market. For more info, check out Sprint's XOHM: What You Need to Know.

XOHM currently exists only in Baltimore, Maryland, though I also detected the network in Philadelphia. Sprint says that coverage in Chicago, Washington D.C., Providence, Boston, and Dallas is in the works, with more cities to follow.

XOHM is debuting with an ExpressCard for Windows (not Mac OS) laptops, the $59.99 Samsung SWC-E100, and a $79.99 home modem from ZyXel (which works with both Windows and Macs). Near-future product options will include the Nokia N810 WiMAX Edition Internet tablet, which we tested; a USB modem from ZTE; and various Windows (not Mac) laptops from a range of mainstream manufacturers. The network works with any WiMAX device—Sprint doesn't have to approve it—but there just aren't many WiMAX devices yet. We'll head down to Baltimore again next week with more gadgetry to try out.

You can attach one of four service plans to your XOHM devices: The "home" plan works with the home modem, for $35 a month (its on sale through December 31st for $25), the "On the go" plan is for the ExpressCard, at $45 a month ($30 until 12/31), and "Pick 2" lets you get two devices (a modem and a card, for instance) for $65 a month ($50 until 12/31). Finally, you can buy a $10 day pass to try out any XOHM device. None of these plans require contracts or credit checks, making it a good choice for students and those with less-than-stellar credit. But I wish Sprint would offer combo plans for existing Sprint customers, or for users who want to roam with EVDO beyond XOHM's very limited range.

The installation process is run-of-the-mill. You sign up for service on the Web, entering an ID (the MAC address) found on your WiMAX device. You must use XOHM's own connection manager software to connect to the Internet. It worked fine on my Apple MacBook Pro running Windows Vista Enterprise, though I sometimes had to restart the PC after waking it from sleep mode to get it to recognize my ExpressCard.

I tested XOHM over a one-day period in six scattered locations across Baltimore: Downtown, Harborplace, Penn Station, Owings Mills, and two spots in Mount Washington.

Right now, coverage is pretty spotty, but that's to be expected from a new wireless network in its first week. It was true of EVDO, it was true of HSDPA, and it's true of WiMAX: Networks start out patchy and then fill in. Still, I was concerned that Sprint's coverage map doesn't tell the whole story. Sprint's mapped dead spots, such as around the Old Court metro station, seem to be accurate. But I found other dead spots that Sprint claims have coverage, such as at the intersection of Falls Road and Northern Parkway.

WiMAX has a tendency to get considerably slower when you're further from a tower, and the relatively short range of 2.5-GHz towers also may explain why I saw my signal vary block by block. At a shopping mall in Mount Washington, for instance, I had a significantly stronger signal on the south side of the mall than on the north side. You don't see these differences so much any more with the mature EVDO cellular networks.

With a strong signal, I saw download speeds averaging 3.6Mbps, with my fastest test at a blazing 7.1Mbps. That's faster than my home cable connection! "Good" upload speeds varied from 416Kbps on up to a really impressive 2.1Mbps.

But speeds dropped sharply with a weak signal. Downloads crawled as slowly as 620Kbps and uploads fell as low as 122Kbps. I still got several download results over 1Mbps, even with a very weak signal.

Interested in the overall averages? That would be 2.3Mbps down and 915Kbps up, which jives with Sprint's advertised range of 2-Mbps to 4Mbps down and 500Kbps to -1,500Kbps up.

The time for a request to travel across the network, a.k.a. latency, has a major effect on how responsive a network feels. I measured latency by pinging a basket of five Web sites. XOHM's average latency, at 133ms, was much lower than that of cellular networks, which usually average around 200-ms to -250ms. I got figures as low as 71ms on one test.

But XOHM's latency is still several times that of Wi-Fi. Testing against a public Wi-Fi hotspot with a Covad DSL backhaul, the Wi-Fi hotspot gave me a latency result of 24 ms. So Wi-Fi feels much faster, because pages start loading more quickly.

When XOHM worked well, I could do things I'd never before dreamed of doing over a cellular connection. A 480p version of "Dr. Horrible's Sing-Along Blog" streamed beautifully from Hulu.com. A new version of Quicktime downloaded at 666Kbps, with the 26.7MB file arriving in under a minute. A 720p movie trailer streamed along for more than a minute before needing to buffer again. In essence, it was a big, fat pipe heading into my laptop.

XOHM mopped the floor with existing cellular networks. I tested the XOHM card side by side with the Editors' Choice Sierra Wireless AC595U on Verizon Wireless's EVDO Rev A network in Baltimore. I achieved decent speeds for EVDO with the AC595U, with most downloads in the range of 700- to 900 Kbps and a peak of 1.9 Mbps. XOHM was in a different class. Of course, EVDO is nationwide. XOHM is only in Baltimore.

A better comparison is with Wi-Fi hotspots, or home cable or DSL connections. And here's where things get tricky. Cable and DSL options can be faster or slower than XOHM. But they're typically more consistent.. If you have 5-Mbps cable, you usually get 5 MBps. Sometimes there will be a ton of traffic in your neighborhood and you'll get less, but it's typically steady. XOHM seemed inconsistent—7 Mbps in one place, 2 Mbps in another. And XOHM's upload speeds are slower than those offered by high-end wired solutions.

Uploads are another concern with XOHM, specifically Sprint's utterly non-net-neutral terms of service. The carrier reserves the right to throttle your connection if you do things it doesn't like, such as a lot of peer-to-peer uploading. These sorts of terms are common on cellular networks, which are very bandwidth-constrained, but they're rare for "home"-style ISPs. If you intend to use your connection for heavy, consistent upstream applications (like BitTorrent or some forms of gaming) you should probably stick with a wired link for now.

I have high hopes for XOHM. It's very early to pass judgment—heck, Sprint hasn't even had its launch party yet. But with more consistent service and a lower price, the carrier could transform the wireless Internet world. If you live in a XOHM city, try it out. But make sure the store at which you buy your device has a fair return policy, in case you wind up in a weak signal area.