Experimental Evaluation of On-body Transmission Characteristics for Wireless Biosensors Hongliang Ren ∗† , Max Meng ∗† , and Chunhoi Cheung ∗ ∗ Department of Electronic Engineering The Chinese University of Hong Kong, Hong Kong, China † Shenzhen Institute of Advanced Integration Technology Chinese Academy of Sciences/The Chinese University of Hong Kong, Shenzhen, China Abstract—Wearable health monitoring system has undergone rapid progress in recent years. Traditional wired biosensor network are inconvenient of interconnecting sensors which not only involve high maintenance costs, but also limit the movements of users. Thus, wireless technology is no doubt that it will have impacts on the healthcare industry. However, wireless connections are not as stable as wired connections. Many factors can reduce the reliability of wireless connections such as the power setting, surrounding environment as well as the gestures of human being. It is our goal to study how these factors affect the links quality. In this paper a prototypical sensor platform is first reported. Then we attach the sensor nodes onto the human body and observe the PRR (packet reception rate), RSSI (Received Signal Strength Indicator) and LQI (Link Quality Indication) to learn on-body channel characteristics and communication behaviours. We hope the experiment results can help researchers construct more reliable and effective wireless biosensor networks. Index Terms - BAN, Sensor Node Platform, Network Protocol, On-body I. I NTRODUCTION The rapid emerging and advancement of wireless sensor networks and wearable sensors technologies will greatly fa- cilitate continuous and ambulatory health monitoring. They allow an individual to closely monitor changes in her or his vital signs and provide feedback to help maintain an opti- mal health monitoring. This attributes to the development of both biosensors and wireless communication systems. During the last years there has been a significant increase in the number and variety of wearable health monitoring devices, ranging from simple pulse monitors to expensive implantable sensors. For building wearable health monitoring systems, one of the most promising approaches is to make advantages of emerging Wireless Body Area Networks (WBANs) [1] . Typically, these sensors are placed on the human body hidden in users clothes allowing monitoring lots of parameters in their native environment. Wireless Biomedical Sensor Networks [1] (WBSN), consists of a collective of various wireless networked low-power biosensor devices, which integrate an embedded microprocessor, radio and a limited amount of storage. With the development of miniature, lightweight sensor technologies, many physiological signals such as EEG, ECG, GSR, blood pressure, blood flow, pulse-oxymeter, glucose level, etc., can be monitored by individual node or pill that is worn, carried or swallowed. The sensor networks are typically carried or worn by the patients and composed many BANs. BAN provides an efficient way to monitor the physiological signals of the patients with high performance, particularly in the hospital environment. The integration of wireless sensor networking techniques and biosensor techniques will help enhance performances of heath care for patients and the elders. However, the practical healthcare applications of sensor networks in medical care are still rare because of many unsolved research topics, such as the challenges stated in [1] [2]. This paper towards building prototype platforms to observe how the sensor network be affected by surrounding factors. We monitor the Packets Reception Rate (PRR), Received Signal Strength Indicator (RSSI) and (Link Quality Indicator) LQI to observe the link quality of the wireless biosensor network. We hope that the experimental results can be further studied to construct more reliable and efficient wireless biosensor networks. The project MediMesh developed by our research group is a prototypical system of BAN, which aims at networking various sensors mounted on Medi platform for the purpose of healthcare monitoring in a hospital environment. The name MediMesh stands for a mesh of Medi sensors for medical applications. The typical application scenarios of MediMesh may be Smart home health monitoring [3], Smart ward [1], Athletic performance monitoring [4], and emergency medical care [5]. As shown in Fig.1, the typical application scenarios [1] of biosensor nodes may be wearable wireless ECG, swal- lowed sensors that can detect enzymes, intestinal acidity, or embedded glucose level monitor. The wearable or embedded biosensors keep sensing the vital signals of the patients and transmitting them wirelessly to the BAN-Head which maybe also a node or even PDA. Then the physiological data are delivered to a backend archival system for long-term storage and diagnosis analysis. The paper is organized in the following orders. We first describe the proposed prototype for the implantation of the WBAN system. Then, we show the experiments we have done and a conclusion is given in the last part. II. DESIGN OF HARDWARE SYSTEM A. Related Projects Some researchers have been engaged on the development of WBAN. CodeBlue project [5], is trying to build up a wireless 1-4244-1092-4/07/$25.00 © 2007IEEE. 745 Proceedings of the 2007 IEEE International Conference on Integration Technology March 20 - 24, 2007, Shenzhen, China Authorized licensed use limited to: Johns Hopkins University. Downloaded on November 9, 2009 at 22:50 from IEEE Xplore. Restrictions apply.