u-헬스케어시스템을 위한 WSN 기반의 고신뢰성 라우팅 프로토콜

Abstract

The rate of elderly population has been increasing rapidly, faster than any other age groups. For the aged group, many of them are facing high risk factors of chronic diseases such as: cardiovascular, stroke, high blood pressure etc. Therefore, a healthcare system is needed to closely monitor the changes of vital signs in elderly patients to provide diagnosis and treatment in order to maintain healthy lives. In recent years, the development of bio-sensor, information and communications technology has led to the combination of healthcare and communications technology. This has produced various opportunities for developing a ubiquitous healthcare system, enabling remote management and the physiological monitoring of chronic disease and emergency conditions. However, existing ubiquitous healthcare systems using general personal area network(PAN) technology have drawback of weak RF strength of wireless signals due to the wireless signals passing through walls. Thus, the communication range is reduced and this leads to a dead spot which causes communication-disconnect between the mobile nodes and gateway. It also limits the moving range of a patient indoors. For this reason, routing protocols in wireless sensor networks(WSN) with self-organizing and multi-hop capabilities can be regarded as special techniques to extend network coverage and to enhance reliability for wireless connectivity in an indoor environment. In this research, an optimal routing protocol has been designed to guarantee reliable vital data transfer in healthcare system. This thesis also presents a reliability evaluation of four WSN-based routing protocols in a ubiquitous healthcare system: Bi-direction MCF, flooding, leach and fast link exchange based Bi-direction protocol. The purpose of these routing protocol evaluations is to satisfy the quality-of-service(QoS) demand in real-time vital signal transmission. Small size, wearable-type mobile nodes based on wireless sensor networks have been designed and developed. The mobile nodes can collect ECG, activity, blood pressure, and blood sugar data signals from the human body and form a multi-hop network with relay nodes to extend the network range in WSN. Performance analysis is done to obtain some important parameters in terms of distance and reception rate between the nodes. Based on this performance evaluation, experiments are carried out to maximize the routing protocol efficiency in relay nodes deployment scheme. In this thesis, a ubiquitous healthcare system had also been designed to achieve mobility and flexibility combining WSN and code division multiple access(CDMA) technology. A query processor is added to mobile phone and mobile nodes to selectively use any devices(ECG, blood pressure and blood sugar module) and control the self-organizing network of mobile nodes in WSN. Vital signs from mobile nodes are analysed using a developed cellular phone application on whether the signs are abnormal or normal using three healthcare parameters:ECG, blood pressure, and blood sugar.

Keyword : u-healthcare system, Wireless sensor network protocol, Flooding, Leach, MCF, Mobile healthcare, wearable healthcare system