Wireless networks on financial trading floors are evolving to support a greater density of traders, who now also use higher-bandwidth applications.

Both the Pacific Exchange in San Francisco and the Chicago Board of Trade (CBOT) are augmenting lower-speed wireless LANs with 54 Mbit/s 802.11a technologies. These organisations say their primary challenge is supporting a very dense volume of traders clustered in relatively small areas, such as trading pits.

The Pacific Exchange, for example, recently replaced a pre-802.11 Proxim RangeLAN2 1.6 Mbit/s wireless infrastructure with an Airespace 802.11a (54 Mbit/s) network on its trading floor. In the mid-1990s, the RangeLAN2 speed was "sufficient for sending trades," says Bruce Burke, network engineer. "Then modern times hit. Traders want [to access] quotes and use a variety of messaging devices to position quotes and trading."

Likewise, John Szpicki, director of network technology at CBOT, says his organisation ran into a "serious limitation with the number of handheld clients" that even 11Mbit/s 802.11b technology could support. Szpicki says 200 traders might be clustered in a 400-square-foot trading pit using the WLAN. Some of the trading applications require 120 kbit/s of bandwidth. "But 200 people sharing an 802.11b network breaks down to about 24 kbit/s per user."

So CBOT is augmenting an existing Cisco 802.11b network with Cisco 802.11a gear. CBOT is running a total of about 45 Cisco access points - chosen initially, Szpicki says, for the security strengths of Cisco LEAP technology (which are doubted in some quarters – Ed).

For his part, the Pacific Exchange's Burke says the Airespace network - which it installed in November - was the best fit because of the versatility of Airespace's antenna design for dynamic coverage range.
"Also, Airespace provides you with a map that shows your coverage in real-time," Burke says. "If something looks weak, you can tweak it."

The Pacific Exchange currently runs six 802.11a access points on the trading floor and has installed two switches, which each support a dozen access points. The exchange still uses Proxim on the client side, running the vendor's PCMCIA 802.11a adapters in Compaq tablet computers. "Within the next couple months, we'll use Airespace in the corporate environment," Burke says.