Overcoming unusual wireless challenges

Computerworld - Golf balls and huge trucks are not normal Wi-Fi hazards, but for Ron Shaul, director of technology at Smart City, an outsourcer specializing in providing voice and data services in large convention centers and sports arenas, these are all in a day's work.

"When the mining conference comes in, they fill the conference floor with huge earthmover trucks 25 feet tall that block signals from the wireless APs in the ceiling," he says. "The PGA turned one of the halls at Las Vegas into a driving range, and someone bounced a ball off one of the APs and broke its antenna. Then the next show might be cowboys, with very little wireless demand at all."

Smart City has long-term contracts to run the networks in 13 major facilities, including the conference centers in Las Vegas, San Diego and Orange County (Orlando) and the Houston Astrodome. In the past year, they installed 802.11 b/g in all these facilities -- a total of 16,000 permanent access points. But that, as it turns out, is just the start of the Wi-Fi project. "We just acquired our largest competitor," Shaul says. "Now we have about 40 facilities, including three in Houston alone."

High volume, sustainability and interference

Wireless has proved very popular in the original 13 Smart City facilities. Sometimes it's almost too popular. The largest challenge Shaul's staff often faces is just handling the very high demand. "There are limits to the number of simultaneous users you can support in an area on b/g's 2.4 GHz," says Shaul. With use doubling annually, "we are hitting the capacity limits."

Often the issue is not the volume of data but the number of authentications the network can handle simultaneously. Adding access points can increase the network's capacity to a point, but too high an AP density leads to interference.

Smart City has responded in two ways. First, it is adding 802.11a to its networks, opening the 5.8 GHz band. While mobile handheld devices seldom support this band, laptops, wireless printers and other larger capability systems often do. So far Smart City is seeing about 20% of the data traffic move to this band. It is hoping that eventually 50% will use the "a" band.

Second, Smart City moved to BlueSocket controllers for all of its Wi-Fi. "We are an all-Cisco shop," Shaul says. "We were using another brand of controller that is prominent in the hospitality industry, but they had trouble scaling to the levels we require."

BlueSocket allows them to double the number of simultaneous authentications they can handle in a given area, eliminates interference among APs and allows them to cover an entire conference floor with a single flat network. This can enable users of mobile devices to wander around the floor without losing their connections