# Validation of Wired and Wireless Interconnected Body Sensor Networks
## 1 Introduction  
Electronic health (e-Health) and mobile health (m-Health) are increasingly considered to be key drivers for the progress of Internet of Things (IoT) based tele-health systems [1]. The current social, economic and ecological trends of massive urbanization and climate changes impose painful changes to the healthcare landscape and further complicate the e-Health paradigm. The massive urbanization moves the focus of healthcare to urban areas and therefore hardens the healthcare capabilities in rural areas. Similar problems are also seen in developing countries where even in urban areas the proper healthcare facilities are not available. Fortunately, advances have been made towards smart living and health monitoring systems that support tele-medicine. In particular, Body Sensor Networks (BSN) [2] and wireless communications [3] represent powerful techniques for significantly advance healthcare in developing countries. In BSN, wearable sensor nodes are deployed over a human body. The sensors can be used externally on the body or inside the human body to measure certain health parameters. For example, measuring the heart rate, body temperature or recording a prolonged electrocardiogram (ECG). These wearable or implantable sensors communicate with the base station (BS) to collect the data and then transmit it to the medicalserver or personal device (smart phones, laptop) or the doctor for further assessment/treatment. BSN is mostly used for long time health monitoring. One of the advantages of using this technology is that a patient need not to stay longer in hospitals and can be monitored remotely. BSN can be either wired or wireless in nature. In wired BSN the sensors scattered on the body are connected using wires to BS. However, in wireless BSN (WBSN) the sensors communicate wirelessly to BS. The generic wired and wireless BSN scenarios are shown in Figure 1.  
In Reference [4] we proposed a wired BSN called as Digital First Aid (DigiAID), that can be applied to patients in emergency situations to compute the level of the urgency in real time and update the corresponding hospital prior to arrival of patients. The DigiAID can also be utilized by normal people to monitor and provide early health indicators to avoid dangerous health situations. In order to validate our proposed design, we have compared the DigiAID system with the existing commercially available product called as Hexoskin [5] by extensive experiments both on male and female subjects. The wired DigiAID collects three vital parameters for health monitoring, that is, heart rate (HR), respiratory rate (RR) and mental status (MS) using three sensors. The sensors are paced on finger, near nose and in hand. Various other sensors can also be integrated in the proposed design depending on the application requirement. However, the wired nature of the design restrict the amount of sensors and its placement on the body. Accordingly, we developed a wireless DigiAID platform to overcome the problems of wired platform. We have used eight sensor nodes over human body at different places pertaining to monitoring application of different body parameters [6] for our wireless DigiAID. The increased number of nodes is also intended to scrutinize the behavior of wireless system in a manifold structure. We converted our wired DigiAID system wirelessly using ZigBee standard for transmitting data over Radio Frequency (RF). ZigBee/IEEE 802.15.4 is adopted by most of the health care networks due to its inherent features of low power consumption [6; 7; 8]. It has ben observed that body movements and postures can have significant effect on the efficient data delivery [9]. Constant motion of human body can alter the position of sensor nodes. These sudden changes can drop links of the nodes with the BS which may lead to no data transfer between the sensors and BS. This results in unreliable delivery of data which can be life threatening for a patient.