24 Hour Fitness USA had a Wi-Fi problem: The wireless LAN bridges it installed between two adjacent corporate buildings in Carlsbad, California, kept crashing every day around noon.

The Lucent 802.11b network would run well in the morning, "then - boom - it went down," says Justin Kwang, manager of networking and security for the 300-site fitness company.

After some investigating, Kwang discovered that the culprit was a nearby biotech company that was sterilising equipment every day at lunchtime in an autoclave, whose electromagnetic emissions disrupted the fitness company's Wi-Fi signal. The biotech company had no choice but to turn on its equipment when it did, so Kwang had to look elsewhere.

One challenge is that the software developers who were writing business applications to run 24 Hour Fitness's workout centers required as much as 10Mb/sec of bandwidth off and on during the day between the two corporate headquarters buildings. But Kwang says digging a 100m trench and running high-bandwidth fibre between the buildings was out of the question for two reasons: high cost and the difficulty of getting permission from building owners.

Also prohibitive was the cost of running dedicated lines between the buildings, Kwang says. The company would have required six T-1s bonded into one logical pipe, and that would cost $6,000 per month. "There's no way I'm going to get six T-1s," he says.

Next up was free-space optics, which involves the transfer of data on a laser beam without using optical cable.

The company chose LightPointe Communications as a vendor and bought a pair of FliteLite 100 boxes. The devices transmitted at 10Mb/sec, but had trouble receiving during morning fog, Kwang says.

The company upgraded to a FliteLite 155 that transmitted at 100Mb/sec. The faster devices cut through the fog problem by using a more powerful laser and better-tuned receivers, Kwang says; however, they also required a transceiver to convert the Category 5 wire signals to optical signals the devices uses.

Currently, the company uses a new version of the FliteLite 100 that requires no transceiver and transmits at 100Mb/sec. The boxes support Power over Ethernet (PoE) too, so they sit on the roofs of the two buildings with no separate power connection needed. Getting permission to install the power and drilling a hole in the roof was a hassle for the earlier models, Kwang says. "It's just painful to bring electricity up there. It's one less thing I have to worry about."

The company uses Cisco switch models that don't support PoE, so it bought separate power injectors that sit in-line with the FliteLite gear, Kwang says.

As an early Wi-Fi customer, 24 Hour Fitness actually got rid of the 802.11 gear before well-publicised security issues started hounding the technology.

"Back then we had no concerns. Nobody knew you could hack 802.11b," Kwang says.

The free-space optics gear solves the security problem because the lasers are focused and cannot be intercepted without disrupting the connection.

The $6,000 that the fitness company paid for the LightPointe devices was a small enough expenditure, compared with the recurring cost of T-1 lines, that it wasn't challenged by corporate finance, Kwang says. "We didn't need to justify anything," he says.