Ultra-wideband and wireless body are network design and optimisation

Wireless body area networks (WBANs) recently have drawn significant attention in telemedicine and mHealth, which comprise intelligent devices on/in the human body to support various healthcare applications for patient care and disease treatment. Impulse radio ultra-wideband (IR-UWB) is a promising potential telemetry technique in WBANs. Owing to its simple electronics and low power emission, it is less likely to affect human tissues or cause interference to other medical equipment. In UWB based WBANs, spectral effiiency and energy efficiency are certainly two of the most important challenges. In this thesis, we will study the spectral efficiency and energy effiiency optimization problems in relay-assisted UWB based WBANs under various practical transmission scenarios. The main work done in this thesis is summarized as follows: (1) Research on energy-saving based relay selection in UWB based WBANs With a pulse based energy consumption model, the energy-saving relay selection criterion is detailed and analyzed. We show that the relay location plays an important role in UWB based WBANs, which motivates us to explore the optimal relay location and power allocation for performance optimization under various scenarios. (2) Spectral efficiency optimization and energy efficiency optimization in singlerelay UWB based WBANs. To maximize the two metrics, we seek the relay with the optimal location together with the corresponding optimal power allocation. We show the necessity of utilization of a relay node in UWB based WBANs in some scenarios. With the joint optimal relay location and power allocation scheme, the network spectral efficiency can be enhanced significantly compared to other transmission schemes. Up to 30 times improvement compared to direct transmission in terms of energy efficiency can be achieved when the battery of the source node is very limited. (3) Research on tradeoff between energy efficiency and spectral efficiency in single-relay UWB based WBANs. To balance performance between energy efficiency and spectral efficiency and optimize the two metrics simultaneously with desirable preferences, a utility for the energy-spectral efficiency tradeoff is constructed. We show that the proposed utility can be a guideline with regard to the relay placement and power allocation in designing the energy-spectral efficient transmission in UWB based WBANs. (4) Preliminary research on spectral efficiency and energy efficiency optimization in multiple-relay UWB based WBANs. We extend the single-relay case to the multiple-relay case. Distributed beamforming problems for the spectral efficiency and energy efficiency optimization are investigated, respectively. The preliminary results show that a considerable improvement can be achieved not only in energy efficiency but also in spectral efficiency by using multiple relays and the optimal relay location varies with the battery power limit of the source node.