Objective: To determine a suitable architecture where wireless biomedical equipment can co-exist with other wireless devices in a corporate Wireless Local Area Network.
Methods: The maximum number of non-overlapping channels found in the 2.4GHz WiFi band is 3. To cover an area with multiple access points, adjacent access point coverage must overlap. These access points cannot transmit on the same channel because of interference. This means a single network requires all 3 channels to cover an area. Consequentially it is only possible to have one network in the 2.4 GHz band.
The vendors (CISCO and Alcatel) recommend using no more than 8 SSIDs in a clinical environment. There are two methods of authentication that these devices can use, pre-shared keys (PSK) or certificate authentication (CA). Each SSID can only have one method of authentication.
Queensland Health plans to implement the following services with their own SSIDs:
• Biomedical Devices (CA)
• Biomedical Devices (PSK)
• Voice (CA)
• Voice (PSK)
• Data Services (CA)
• Data Services (PSK)
• Video
• University Access
• Guest Access
Results: The number of SSIDs that can be used for biomedical equipment is dependant on the number of other services that will utilise the wireless network and the types of authentication. PSK becomes unmanageable with many devices.
Conclusions: The following recommendations will be made for deploying wireless biomedical devices:
• Only one network can exist in the 2.4 GHz band
• Biomedical devices share an SSID.
• Certificate authentication is used where ever possible