Sprint's 4G Xohm WiMax: How Fast Is It?

With most American mobile data networks busy trying to deliver third-generation (3G) mobile wireless access to traveling businesspeople, Sprint's newly launched Xohm service takes a giant step forward by offering America's first 4G system.

Based on WiMax technology, it can deliver broadband data speeds to notebooks, Internet tablets and eventually smartphones. But at the moment, there aren't many devices to connect with, the network is struggling with reliability issues, and the high-speed service is limited to just one city -- Baltimore.

WiMax (Worldwide Interoperability for Microwave Access) is a wireless data system based on Orthogonal Frequency-Division Multiple Access (OFDMA) technology and the IEEE's 802.16e spec. That's a lot to swallow, but Xohm's basic facts are that it broadcasts on the 2.5-GHz portion of the radio frequency spectrum, a slightly higher frequency than the 2.4 GHz that the 802.11b/g/n standards, commonly used in Wi-Fi networks, operate on.

Because it has a longer range and can deliver higher data rates than 3G services, WiMax has the power to transform the way we think of wireless data delivery. Think about receiving the equivalent of a home DSL or cable broadband connection while you're mobile, and you get an idea of its potential to put data everywhere you'll be. In other words, WiMax can turn a city into a hot spot for wireless data.

"WiMax is Wi-Fi's big sister," says Sean Maloney, Intel's executive vice president. "It will have a big impact on mobility by covering a larger area. The future is here, now."

In the lab, WiMax can deliver a peak data speed of 40Mbit/sec. But in the real world, speed depends on things like how far you are from a transmitting tower, how many others are using the network and the general health of the Internet. Expect to see download speeds between 3Mbit/sec. and 5Mbit/sec., or about three times what the current 3G networks from AT&T, Sprint and Verizon can deliver.

The technology first went commercial in South Korea in 2006 under the name WiBro. Available in 407 locations in 133 countries, according to the WiMax Forum, the wireless system is prominently used in South Korea, Italy, Taiwan, Brazil and Japan every day for a variety of uses.
Enter Xohm

To see just what WiMax is, how it works and what it's actually capable of, I went to Baltimore, the first U.S. city to offer WiMax service commercially, to try it out. Called Xohm, the new network is a joint venture of Sprint and Clearwire.

So far, Xohm has spent about $3.2 billion to develop, test and roll out WiMax in a few places, according to Sprint CEO Dan Hesse. "It's just the start. Another $5 billion will be required to create a national network," he explains. Google, Intel and several cable companies have invested an additional $3 billion in the project.

What can you expect from the Xohm network? First of all, its deployment is obviously very limited at this point. It's as if you wanted to call to order a pizza a month after Alexander Graham Bell's first phone call. There just aren't enough places in which to use it.

Baltimore has 180 WiMax towers in use, out of an expected total of 300 when the deployment is complete. "We have coverage of 70% of the city," explains Bin Shen, Xohm's vice president of product and partnership management.


Cities of the Future

The plan is to expand beyond Baltimore to include Washington, Chicago, Boston, Dallas, Philadelphia and Providence, R.I., in the coming weeks and months.

"We'll build out the network so that it will be available to where 80 million people live or work by the end of 2009," adds Shen. "By 2010, the plan is to have a network that reaches 140 million people. In 2011, Xohm will match the coverage of Sprint's current 3G EV-DO network."

It's extremely ambitious to build out a wireless network in less than three years, but Monica Paolini of Sammamish, Wash.-based Senza Fili Consulting, says, "This is a realistic schedule, but only as long as the money holds out. To succeed, Xohm needs to simultaneously have devices available, a working network and customers."
How fast is it?

Speed is of the essence when it comes to WiMax. I spent the better part of a day roaming around Baltimore, testing the network at six locations using SpeedTest's online bandwidth meter. As a test system, I used a Lenovo ThinkPad X301 with built-in WiMax as well as a Sierra Wireless AirCard 875U that works with AT&T's BroadbandConnect data network.

The Xohm network delivered a peak download speed of 4.4Mbit/sec., while AT&T could muster only 1.7Mbit/sec. -- that's nearly three times the throughput at exactly the same locations. During a drive around the city, the hand-offs from tower to tower were seamless and glitch-free. WiMax can deliver data to a car moving at highway speeds, perfect for back-seat surfing or doing work on a commuter train.

On average, Xohm pushed through more than 3Mbit/sec., compared with 1.3 Mbit/sec. for the AT&T network. More to the point, the latency of the WiMax network was about one-third that of the AT&T network, meaning that the data you need won't be sitting on servers waiting for an active connection to transmit it to your notebook. This streamlines access and downloads.

At almost all of the locations I tested, Xohm quickly brought up YouTube and played videos flawlessly, while the AT&T network balked a couple of times and once produced jittery video with unsynchronized audio.

As good as it is, however, Xohm is not perfect, and its engineers need to work out some of the early bugs. At one location, I wasn't able to connect to Xohm at all, while five feet away, I got on quickly with 4Mbit/sec. of bandwidth at my disposal.

Barry West, Xohm's CEO, chalks this up to a network that still needs to be completed. "There are bubbles of connectivity with spaces in between," he says. "You can't build a network overnight."
Getting online the WiMax way

A bigger problem is the paucity of devices that can connect to the network. At this point, there are only a handful of devices available. Here are some highlights.
Modems and data cards

These devices connect your existing laptop or desktop computer to the Xohm service.

Despite looking like a futuristic coffee maker or an alien spaceship, Zyxel's Xohm Modem, model MAX206M2, is the equivalent of a cable or DSL modem for the Xohm network. It has an Ethernet jack on the back to connect it to a home router to distribute the data throughout a house or apartment. Sure, it's big and clunky (6.5 by 6.45 by 4.65 in.), but it's meant to be hidden. It costs $80.

Samsung 's Xohm ExpressCard, SWC-E100, weighs 1.3 ounces and works like a charm for accessing the network. The good news is that setup is quick and easy; the bad news is that the card doesn't work with Mac or Linux computers, cutting into its usefulness. The card costs $60.

Look for ZTE and Motorola to introduce USB adapters that can transform many notebooks into WiMax systems. But as with the ExpressCard, this will be a Windows-only data party, with Mac and Linux systems left out in the cold.

Laptops and Internet Devices


In the market for a new notebook or mobile Internet device? A handful are starting to add built-in WiMax connectivity.

Representative among the new breed is the Lenovo ThinkPad X301. A dead ringer for the ThinkPad X300 on the outside, the X301 updates the system with Intel's latest Montevino processors and built-in WiMax that sits on a mini-USB module. The best part is that the hardware works perfectly with Lenovo's Access Connections software, so it's easy to go from Wi-Fi to WiMax and back again. The connected notebook costs $2,556.

Other WiMax-capable laptops include the Asus M50Vm and the Lenovo ThinkPad SL300, SL500 and T400; soon-to-be-released models include the Acer Aspire 6930 and 4930, the Asus N50Vn-B2WM and F8Va-C2WM, and the Toshiba Satellite U405-ST550W.

"By the end of the year, there will be a dozen WiMax notebooks," says Xohm's West.

But without a doubt, the most exciting product for this new technology is Nokia's N810 WiMax Edition. This hand-friendly Internet tablet squeezes the Web and all it has to offer into a 4-in. 800 x 480 screen. When you're away from a WiMax network, the N810 can connect with its built-in Wi-Fi.

Oddly enough, the missing link is phones. None of Xohm's service plans or device info includes any traditional handsets or smartphones, a key gap in the company's plans.

Xohm's West counters, "For us, voice is just another app. We encourage people to use voice over IP on Xohm." In other words, there will be Xohm phones for sale, but no specific models or dates have been mentioned.

As good as Xohm is, the majority of Sprint's network still uses older and slower EV-DO technology, which leaves a critical gap because there are no dual-network devices available. A dual-network connection card would allow a user in Seattle to tap into the older network but get full speed in Baltimore. West says to expect the first dual-network devices later this year.

The big question is how expensive they will be to use. They will require access to both the old and the new networks, so I expect it to cost more than a single subscription. On the other hand, you won't be able to access two networks at once, which should keep the price of the service plans reasonable.
Shaking up wireless data service

Xohm has rewritten the business model for mobile data by doing away with the subsidies that carriers use to lower the price of phones and data cards to entice new customers.

Over the life of a typical two-year contract, a service's monthly bills are about $10 to $15 higher when you get a discounted device upfront. It's no wonder you can get a free phone or data card when you factor in the extra $240 to $360 the carrier will rake in over time.

By contrast, Xohm users won't need any long-term contract and will get lower prices on monthly service. "This brings simplicity to pricing," says West.

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