Prototype design of mobile emergency telemedicine system

High bit rate wireless cellular service using CDMA 1X-EVDO is now popular in Korea, particularly in urban areas, since it was launched commercially in 2002. This cellular service allows the real-time transmission of patient images and vital sign signals simultaneously in a moving ambulance application. In this paper, we designed a prototype emergency telemedicine system that can transfer both biological signal and patient motion video from a moving vehicle using a CDMA 1X-EVDO reverse link. To cope with the limited bandwidth of the reverse link (transmission bandwidth of cellular device) relative to the the forward link (receiving bandwidth), priority control between the vital sign and video images, frame rate control using MPEG-4 compression, and error control using automatic repeat request were incorporated into the application layer protocol of the designed prototype system. Many on-road experiments have been performed to evaluate the actual performance and to demonstrate the applicability in a real situation. In most cases, the biological signal and patient video images with reduced frame rate were successfully transmitted from the moving vehicle in urban areas