Wireless local area network in a prehospital environment

Abstract

Background: Wireless local area networks (WLANs) are considered the next generation of clinical data network. They open the possibility for capturing clinical data in a prehospital setting (e.g., a patient's home) using various devices, such as personal digital assistants, laptops, digital electrocardiogram (EKG) machines, and even cellular phones, and transmitting the captured data to a physician or hospital. The transmission rate is crucial to the applicability of the technology in the prehospital setting.

Methods: We created two separate WLANs to simulate a virtual local are network environment such as in a patient's home or an emergency room (ER). The effects of different methods of data transmission, number of clients, and roaming among different access points on the file transfer rate were determined.

Results: The present results suggest that it is feasible to transfer small files such as patient demographics and EKG data from the patient's home to the ER at a reasonable speed. Encryption, user control, and access control were implemented and results discussed.

Conclusions: Implementing a WLAN in a centrally managed and multiple-layer-controlled access control server is the key to ensuring its security and accessibility. Future studies should focus on product capacity, speed, compatibility, interoperability, and security management.

Figure 1

An aerial view of the use of a patch antenna at a simulated patient's home. The AP – clients connection (A and B) and peer-to-peer connection (C and D) configurations were tested. The arrows indicate the locations and the beaming directions of the APs with a patch antenna. The stars indicate the locations of the wireless devices in the peer-to-peer connections. The link statuses were measured as described in the Methods: the solid and dashed circles indicate "excellent" and "good" statuses, respectively. Panel A: Simulated ambulance parked on the street. Panel B: Simulated ambulance parked in the parking lot of the house. C and D: Peer-to-peer connection was created between two wireless clients.

Figure 2

The Cisco Secure ACS and its configuration. The AP was configured to use ACS AAA services for the Extensible Authentication Protocol (EAP)-enabled wireless devices over the WLAN. A Windows 2000 Server running Active Directory (AD) was used to mimic a network access server (NAS) to negotiate with ACS through the Remote Access Dial-in User Service (RADIUS) protocol. The NAS had an enabled RAS connection for the ACS.

Figure 3

A private WLAN with an ACS. A workstation running the Linux operating system functioned as a Network Address Translation (NAT) server. The private LAN was linked with the Internet through a switched hub or router. The AP was configured to use ACS for AAA services for the EAP-enabled wireless devices over the WLAN. A Windows 2000 Server running Active Directory was used to mimic a NAS to negotiate with ACS through the RADIUS protocol.