Until deployments ramp up to near-mainstream status, the jury will likely remain out on whether Wi-Fi is an apt technology upon which to base public network services - consumer, business, municipal and public safety. After all, only when the unlicensed airwaves get heavily used and start knocking into one another will the technology's mettle really be tested.

On the one hand, several municipalities have built - or are in the process of building - muni Wi-Fi mesh nets for their city workers, citizens, visitors and business users. Dayton, Ohio; Lebanon, Oregon; Mountain View, California; Philadelphia; San Francisco; and Tempe, Arizona, all pop to mind.

In fact, there's now even a country-wide, 1200-square-mile Wi-Fi net throughout Macedonia built on Strix mesh Wi-Fi technology, reportedly poised to serve 2 million customers.

Firstly - it works!
I think most pundits would agree that the technology works. It's got multimegabit bandwidth, is initially inexpensive, scales easily as you need to grow the network, and is smart enough to route around interference - if, in fact, there's anywhere for uncongested traffic to go. At least some of the mesh vendors have engineered fast-roaming and handoff into their proprietary mesh routing protocols, enabling Wi-Fi to become a "mobile" technology. And, by Jove, Wi-Fi products are available, standardised, and interoperability-tested (unlike WiMax).

The drawbacks
The fact that Wi-Fi doesn't require licensed spectrum, though, is a double-edged sword: It makes the networks fast, easy, and relatively cheap to deploy. It also makes them susceptible to innocent or deliberate interference.

And since no one owns - and thus can legitimately control - the unlicensed airwaves in aggregate, no one service provider can really assure you of any particular service quality. And how does your provider troubleshoot the service and provide meaningful help desk services if your performance degrades because of outside influences?

Make it directional
More technology might provide a partial answer. MetroFi is already offering some Wi-Fi services for $19.95 a month in Silicon Valley using SkyPilot mesh gear, which supports proprietary, WiMax-like scheduled access technology for QoS.

MetroFi chief executive and co-founder Chuck Haas says the company also uses highly directional antennas to overcome interference - "it's like putting blinders on" the air path, he says.

Using these techniques, MetroFi is able to provide guaranteed speeds of 1Mbit/s downlink and help desk services. This gives its fee-based structure some legs for competing against Google, which will initially offer no service guarantees with its free Wi-Fi service to become available in Mountain View sometime next spring.

Some other points of interest

  • For public safety purposes, Wi-Fi offers good bandwidth. But by itself, it isn't an optimum technology for speeding down the street after suspects at 100 miles an hour. Check that your provider has built in fast roaming and handoff into its mesh routing algorithm and at what speeds mobile mesh devices can communicate, both with one another and back to stationary access points. If these capabilities aren't present, you may also need special tracking software at the back end and client/server mobility software from IBM, Ecutel, NetMotion Wireless, Padcom or other "session-persistence" vendor.
  • For more static scenarios, such as a crime scene or fire, Wi-Fi holds more promise. Start-up PacketHop, for example, contends that it gets around the whole infrastructure interference and overload issue during an emergency by outfitting all public safety emergency responders with mesh software that turns their Wi-Fi devices into instant but temporary local Wi-Fi mesh networks that can operate with or without a Wi-Fi access point.

    Members of the ad hoc group are both clients and backbone devices, communicating video and whiteboard drawings to one another of exactly where personnel are needed.

  • Some Wi-Fi mesh vendors support slots for WiMax (which supports QoS in the standard and will run in licensed bands). But which network operators can get licenses?
  • Note that early WiMax equipment is also being built for the 3.5 GHz band for regions outside the US, and Intel is lobbying in Washington to get slices of 3.650 GHz set aside in North America for WiMax. No report on its success so far, but equipment designed for 3.5 GHz should also work in 3.650 GHz, according to Intel.