Choosing sides: Wi-Fi or EV-DO?

If your company is in Tempe, Ariz., you're now faced with a decision: Should you spend money on metro-area Wi-Fi services or cellular data services such as 1X EV-DO?

As with most things wireless, the answer is not simple. You might pay for both, depending on your end users' requirements and applications.

Yet Wi-Fi providers have been touting lower monthly fees and higher bandwidth compared with cellular providers for services such as Internet access, VPN connections to corporate networks and voice over IP (VoIP) calls. Those services are being marketed both to businesses and individual mobile users.

To deliver these services, mesh networks based on the IEEE 802.11 standards are being set up to blanket large areas, such as the Wireless Access Zone Tempe (WAZTempe) network, which was completed just last week by network operator NeoReach Wireless, a division of MobilePro. Like nearly all such networks, WAZTempe operates in the unlicensed 2.4-GHz and 5-GHz radio bands.

The network consists of 550 outdoor, multiradio access points from Strix Systems. Each access point has two 802.11b/g to connect to client devices, and two 802.11a radios to route the traffic with neighboring access points. At 12 locations, these devices are wired into a newly built fiber Gigabit Ethernet ring, from Cox Communications Inc.

NeoReach authenticates users via 802.1X over an encrypted connection, assigns them to different virtual LANs and can enforce different QoS, depending on what plan a customer has chosen, says Ryan McCaigue, director of engineering at NeoReach.

So far, NeoReach and the retail network providers who offer service over the wireless infrastructure have signed up 1,500 subscribers. A key target is businesses, which are offered higher bandwidth, more stringent QoS guarantees and specialized equipment like high-gain or direction antennas.

Plans start at $29 a month, with bandwidth of up to 384Kbit/sec. upstream and up to 1Mbit/sec. downstream. By contrast, McCaigue says his own cell phone package costs about $60 a month for voice only, with the option of spending another $40 a month for data services at about 200Kbit/sec. to 400Kbit/sec.

Sounds like a no-brainer for network executives, right?

No-brainer no-how

Well, no, according to critics.

Yankee Research Group Inc. just issued a report called "Myths and Realities of Wi-Fi Mesh Networking" in which co-author Phil Redman summed up the conclusion. "There is a limit to how far you can push an unlicensed radio technology," he says. That's true even as the rapid pace of Wi-Fi innovation, including 802.11n, which promises bandwidth of 300Mbit/sec. to 400Mbit/sec. in 2007, enables providers to push that limit.

But providers such as NeoReach and vendors like Strix Systems Inc., Tropos Networks Inc. and BelAir Networks Inc. point to scores of metro-area deployments around the U.S. as evidence that Wi-Fi mesh networks are viable.

"If we're talking about just the technology, then these types of networks designed to cover what I call 'localized regions,' with the intention of having a modest level of usage, make sense," Redman acknowledges.

But whether Wi-Fi networks can succeed as sustainable businesses is unclear, he says. "It's very difficult for a [Wi-Fi] business model to work in isolation from another service that has a reasonable level of market scale" such as wide-area cellular services, he says.

Mobile worker needs

Bob Egan, director of emergent technologies at consultancy Tower Group Inc., is also skeptical about Wi-Fi mesh being able to deliver for mobile enterprises.

"802.11 was never intended and will never be a metro architecture," says Egan, an author of the original 802.11 standard. "Metro [Wi-Fi] nets are just a venture capitalist wish and not an architectural reality."

He suggests imagining yourself in a coffee shop working on your wireless laptop trying to finalize a customer deal and three teenagers next to you are playing on a bandwidth-hungry wireless gaming console. "You're trying to make money, and they're not," Egan says. "How does this make sense from a business standpoint?"

Meanwhile, Sprint Nextel Corp.'s EV-DO service offers business users two plans. The first, Flexible Connection, is a 40MB plan for $40 per month. Customers will pay $.001 per kilobyte over 40MB with a maximum monthly charge of $100. The second, Unlimited Connection, is $80 per month for unlimited wireless data access.

A sometimes hidden cost of Wi-Fi service is having to pay vendors in separate locations for access during the course of a workday or workweek. However, that's less of a problem when the enterprise has contracts with Wi-Fi aggregators.

Where EV-DO is available, the services average 400Kbit/sec. to 700Kbit/sec. data transmission speeds, with a maximum of up to 2Mbit/sec. Using the same wireless access card, customers can still access the Internet using Sprint's slower PCS network, which is equivalent to using a dial-up modem or DSL.

Uniform, consistent, simple

Those speeds, along with uniform, consistent, simple and secure access no matter where you are in the service area, seem to be driving enterprise adoption of cellular data services. Sierra Wireless Inc. builds cellular cards for several carriers, including Sprint and Verizon Communications Inc. For the newest EV-DO and High Speed Downlink Packet Access wireless cards, "our growth has been dramatic" says Greg Speakman, director of marketing for mobile products at Sierra. The company, which doesn't release unit shipments, has its EV-DO modems built into laptops from Lenovo Group Inc. and Hewlett-Packard Co. (and offerings from Fujitsu Siemens Computers are on the way in Europe).

For his part, NeoReach's McCaigue isn't anticipating network problems in Tempe. Interference issues can be sidestepped and two client radios in each access point provide more than enough connections and capacity for the expected density of simultaneous users, he says.

Senior editor Denise Pappalardo contributed to this story.

This story, "Choosing sides: Wi-Fi or EV-DO?" was originally published by Network World.


Copyright © 2006 IDG Communications, Inc.

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