Free-space optics keeps fitness center in shape

Laser-based campus technology overcomes Wi-Fi shortcoming.

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

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

After some investigating, Kwong discovered that the culprit was a nearby biotech company that was sterilizing equipment every day at lunchtime in an autoclave whose electromagnetic radiation 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 Kwong 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 10M bit/sec of bandwidth off and on during the day between the two corporate headquarters buildings. But Kwong says digging a trench and running high-bandwidth fiber between the buildings was out of the question for two reasons: high cost and the difficulty of getting permission from building owners.

Cost was also prohibitive for running dedicated lines across the 100-yard span between buildings, Kwong 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 as a vendor and bought a pair of Flightlite 100  boxes. The devices transmitted at 10M bit/sec, but had trouble receiving during morning fog, Kwong says.

The company upgraded to a Flightlite 155 that transmitted at 100M bit/sec, but required a transceiver to convert Category 5 wire signals to optical signals the devices uses. The faster devices also cut through the fog problem by using a more powerful laser and better-tuned receivers, Kwong says.

Currently, the company uses a new version of the Flightlite 100 that requires no transceiver and transmits at 100M bit/sec. The boxes also support Power over Ethernet (PoE), so they sit on the roofs of the two buildings but require no separate power connection. Getting permission to install the power and drilling a hole in the roof was a hassle for the earlier models, Kwong says. “It’s just painful to bring electricity up there. It’s one less thing I have to worry about,” he says.

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

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

“Back then we had no concerns. Nobody knew you could hack 802.11b,” Kwong 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-1s – that it wasn’t challenged by corporate finance, Kwong says. “We didn’t need to justify anything,” he says.