Hybrid Interference Mitigation Model for Wireless Body Area Sensor Networks in high Mobility Multi-WBAN Scenarios

Abstract

In the recent past, the field of Wireless Sensor Networks (WSNs) has revolutionized tremendously and has been adopted widely in various todays’ applications due to the increasing demand for smart technology and increase for the need for adaptation of Internet of Things (IoT). Some of these fields include industrial, building automation, transport, environment and weather, security, wildlife management, medicine and health care among others. Among these, one of the most important and recent application is in the field of healthcare (or medical) through recent development of the IEEE 802.15.6 Wireless Body Area Networks (WBANs) standard specifically to address the special needs of the WBAN. The unique operational modality of the WBANs is that a few sensor nodes are placed in or around the body and that they are meant to operate within a limited condition while providing high performance in terms of WBAN life time, high throughput, high data reliability, minimum or no delay and low power consumption (due to miniature nature of the sensor nodes). This is because the WBAN in medical application is adopted in life saving applications where the body sensor network monitors vital physiological body behaviours and signs, reporting the same to a centralised or a remote health monitoring system. This means that the reliability, availability, quality of service (QoS) of the WBAN is of utmost importance and lifesaving. As most of the WBAN operates within the universal Industrial, Scientific and Medical (ISM) Narrow Band (NB) wireless band (2.4Ghz) frequency band, this has posed a challenge in respect to inter, intra and co-channel interference especially in dense areas and high mobility scenarios. As well, human body exhibits postural mobility which affects distances and connections between different sensor nodes within the body. By means of simulation, this thesis investigates these effects on the performance of WBAN under multi-WBAN and WBAN mobility scenarios and the results confirm degradation of the WBAN performance (bandwidth efficiency, network throughput and delay). The thesis thereafter presents a hybrid WBAN interference mitigation model (HIMM) based on two approaches, the CSMA/CA Contention Window (CW) with User Priority (UP) and dynamic cluster head selection (DCHS) based on Link-state (LS) approach. Using Omnet++ simulation tool with Mixim framework, the new HIMM model is evaluated in comparison to the current IEEE 802.15.6 WBAN technology in respect to bandwidth efficiency, network throughput and network delay performance metrics. The results show that the new HIMM WBAN interference mitigation model presented in this research outperformed the existing IEEE 802.15.6 based WBAN technology in the reference areas of network delay, bandwidth efficiency and network throughput. With bandwidth efficiency improvement from average of 30% to over 60% being achieved, network throughput improvement from 51Kbps to 110Kbps and network delay reduction from average of 30ms to 10ms. This is a significant contribution to the future and adaptability of IEEE 802.15.6 WBAN technology in the growing challenging modern operational environments.