Experimental Analysis for Optimal Separation between Sensor and Base Station in WBANs Zuneera Aziz * , Umair Mujtaba Qureshi * , Faisal Karim Shaikh *† , Nafeesa Bohra * , Abdelmajid Khelil ‡ , Emad Felemban † * Department of Telecommunication Engg., Mehran UET, Jamshoro, Pakistan. Email: {zunera.aziz|umair.mujtaba|nafeesa.zaki}@tl.muet.edu.pk † STU, Umm Al-Qura University, Makkah, Saudi Arabia. Email: {fkshaikh|eafelemban}@uqu.edu.sa ‡ TU Darmstadt, Germany. Email: abdelmajid.khelil@ieee.org Abstract—The reliable delivery of data is important in de- signing Wireless Body Area Networks (WBANs) employed for critical applications such as e-health. In order to communicate the data reliably from the sensors to the base station, the data transmission technique (star or multi-hop) and the transmission power plays a very important role. As transmission power is increased, transmission distance is increased and the data can be sent reliably to far nodes. However, in WBANs, there is always a limit to increase the transmission power. Keeping the power level at some low threshold and increasing the distance between a sensor and the base station results in reduced received power which ultimately degrades the data transmission. Thus, for star data transmission technique, the point to ponder is the maximum separation between a sensor and the base station to transmit the data reliably. The reliability in WBANs can be analyzed through different parameters such as received power, received signal strength indicator, link quality indicator, packet error rate, packet reception rate, etc. This paper aims at performing a reli- ability analysis for WBAN through the mentioned parameters to suggest an optimal sensor/base station separation using star data transmission technique. This analysis is performed employing the default routing protocol in TinyOS called the Collection Tree Protocol. Our study considers different sensor placements on different parts of the body as well as different angular offsets between sensor and base station. I. I NTRODUCTION The rising cost of medical procedures and monitoring patients have led to the design of miniaturized wearable and communicating sensors which can be deployed over the human body. These sensors form a wireless network called as Wireless Body Area Network (WBAN) which can communicate with the outside world or the respective entity through a base station [1]. This accounts for intelligent networks consisting of wearable sensors to enable promising applications. These net- works have been further exploited to cater other applications such as applications related to lifestyle and sports [2]. As a modern trend, smart phones are being equipped with sensors to deal with health-care and other WBAN applications. In WBAN generally the sensors are deployed on human body in order to collect data about the vital signs such as heart rate, blood pressure, Electrocardiography (ECG), and temperature and route the data to the base station as shown in Fig. 1. The base station sends the collected data to the Medical Health Service (MHS) through WiFi or a third party carrier using 3G/4G. The doctor can analyze the data and instruct the patient accordingly using the MHS. However, an on-going research area is the usage of actuators [3] where the data can also be sent to the device from the doctor that has to start taking the action (e.g., insulin as an actuator). S2 S1 S3 BS BS MHS WiFi 3G/4G S1, S2, S3 = on body sensors BS = base station MHS = medical health service S2 S1 S3 Fig. 1. General scenario of data transmission in WBANs Generally, the WBAN applications related to health-care are very crucial [4]. For instance during a catastrophic condition such as earthquake a reliable data transfer of vital signs from WBAN to the respective MHS is required. Similarly, if a patient require continuous cardiac monitoring and in a worst case scenario requires an immediate medical attention, the unreliable communication may result in loss of precious life of a patient. Therefore, the network architecture and data transmission techniques play a vital role in assessing the reliability of WBAN. The reliability in WBANs highly depends on the data transmission protocols, the distance between the sensors and the base station as well as the transmission power [5]. This paper analyzes the reliability of data transmission based on Received Signal Strength Indicator (RSSI), Packet Error Rate (PER), Packet Reception Ratio (PRR), Link Quality Indicator (LQI). The analysis suggests an optimal placement of sensors 2014 IEEE 16th International Conference on e-Health Networking, Applications and Services (Healthcom) 978-1-4799-6644-8/14/$31.00 ©2014 IEEE 437