Energy saving and reliability of wireless body area networks for health applications

A Wireless Body Sensor Network (WBSN) consists of several biological sensors. WBSN can be employed to monitor patients’ medical conditions. Energy consumption and reliability are critical issues in WBSNs, as the nodes that are placed near the sink node consume more energy. All biomedical packets are aggregated through these nodes, forming a bottleneck zone. The nodes usually use small batteries and in the case of implantable devices; it is important to prolong battery life. The main consideration of this thesis is the reduction of energy consumption of WBSN devices (sensor nodes) and the successful delivery of biomedical data at sink nodes based on medium access control (MAC) protocol IEEE 802.15.4 standard. A novel mathematical model for WBSN topology is proposed in this thesis to explain the deployment of and connection between biosensor nodes, simple relay nodes, network coding relay nodes, and the sink node. Also, the Coordinated Duty Cycle Algorithm (CDCA) is the proposed novel approach which is adopted for the body area network. CDCA achieves energy savings for nodes through the implementation of mechanisms such as the selection of superframe order based on real traffic and the priority of the nodes in the WBSN, and the calculation of the Coordinated Duty Cycle (CDC). In addition, RLNC is employed to achieve the required level of reliability in WBSNs and delivery of packets through the calculation of the probability of successful reception at the sink node. This research identified that energy consumption in WBSNs is affected by the following parameters: the distances and locations of the nodes on the human body, WBSN topology, employing relay nodes, the propagation model such as the line of sight (LOS) and the non-line of sight (NLOS). Simulation results are presented to show that CDCA improves the energy consumption of biosensor nodes. Also, the results from a comparative analysis of RLNC and XOR NC show that RLNC provides a higher probability of successful reception of data packets at the sink node than the XOR NC technique. Overall, this work demonstrates a new scheme for achieving energy reductions for the biosensor nodes in WBSNs which operate at low data rate; also, it achieves the required level of reliability in WBSNs.