C9-3
Original WLAN St. Luke’s first WLAN was deployed in January 1998 and made the hospital
an early pioneer in wireless health care applications. St. Luke’s first wireless
LAN was implemented in a single building using access points (APs) made by
Proxim (www.proxim.com).
A principal goal of this initial installation was to improve efficiency.
However, sometimes the WLAN had the opposite effect. The main problem
was dropped connections. As a user moved about the building, there was a
tendency for the WLAN to drop the connection rather than performing the
desired handoff to another access point. As a result, a user had to
reestablish the connection, log into the application again, and reenter
whatever data might have been lost.
There were physical problems as well. The walls in part of the building
were constructed around chicken wire, which interfered with radio waves.
Some patients’ rooms were located in pockets with weak radio signals. For
these rooms, a nurse or doctor would sometimes lose a connection and have
to step out into the hallway to reconnect. Microwave ovens in the
kitchenettes on each floor were also a source of interference.
Finally, as more users were added to the system, the Proxim APs, with a
capacity of 1.2 Mbps, became increasingly inadequate, causing ongoing
performance issues.
Enhanced LAN To overcome the problems with their original WLAN and reap the potential
benefits listed earlier in this case study, St. Luke’s made two changes
[CONR03, NETM03]. First, the hospital phased out the Proxim APs and
replaced them with Cisco Aironet (www.cisco.com) APs. The Cisco APs, using
IEEE 802.11b, operated at 11 Mbps. Also, the Cisco APs used direct