Impulse radio based UWB MAC protocols in wireless personal area networks

Abstract

In this dissertation, we are concerned with new MAC protocols of impulse radio based UWB (IR-UWB) in low rate wireless personal area networks (LR-WPANs) or wireless sensor networks (WSNs). We investigate the requirements of IR-UWB based MAC protocols by characterizing the features of IR-UWB and applying IR-UWB to the conventional MAC protocols. First, in order to investigate how an IR-UWB system affects the performance of the CSMA/CA MAC protocol, we apply the IR-UWB system to the slotted CSMA/CA of the IEEE 802.15.4 MAC protocol, which was adopted by IEEE 802.15.4a. We propose a new analytical model of the slotted CSMA/CA under the assumption of perfect carrier sensing. The proposed analytical model reflects the features of IEEE 802.15.4 MAC protocols, such as a superframe structure, acknowledgements, and retransmissions under unsaturated traffic conditions. We investigate the performance of CCA in the IR-UWB system to show the effect of clear channel assessment (CCA) for the CSMA/CA. Second, we evaluate the performance of the THMA based on the IR-UWB system at the physical and MAC layers in order to investigate the feasibility of the IR-UWB for LR-WPANs or WSNs. We here need a cross-layer approach to evaluate the performance. To mitigate the effect of IR-UWB interference, we propose a new THMA based multiple access scheme, which is called `orthogonal time hopping multiple access (OTHMA)` and compare the performance of the proposed scheme and the conventional THMA in terms of SER and FER at the physical layer. Based on the symbol error rate (SER) and frame error rate (FER) results at the physical layer, we develop an analytical discrete-time Markov chain (DTMC) model to investigate the MAC performance of the OTHMA and the THMA, and evaluate the performance of the proposed OTHMA and the THMA in terms of system throughput, average delay, and bits per energy at the MAC layer. We also compare the performance with the OTHMA, the THMA, and the CSMA/CA at...