Analytical performance evaluation of ultra-wideband multiple access schemes for different wireless sensor network application environments

One of the most promising uses for ultra-wideband (UWB) is wireless sensor networks (WSNs). Since WSNs offer a wide variety of services for different application areas, the UWB propagation channel characteristics of each application environment show fundamental differences from each other in many aspects. A reliable and energy-efficient multiple access scheme is thus required to coordinate the transmissions of sensor nodes in these various application channel environments. We develop an analytical framework for evaluating the performance of UWB time-hopping (TH), direct sequence (DS) and orthogonal frequency division multiplexing (OFDM) multiple access schemes with multi-node interference in the following UWB propagation channel environments that have a high importance for WSN applications: residential, office, suburban outdoor, industrial and agricultural. The objective is to determine the most appropriate multiple access scheme to be applied for a particular WSN application channel environment. Performance is evaluated in terms of the average information throughput efficiency, a relevant progress-related measure for multihop WSNs. The mathematical expression of this metric is derived in detail, and is used in numerical evaluations for assessing the performance of the three schemes operating under UWB propagation channel models of the various environments that are characterised by distinct channel parameters and specific valid distance ranges. TH-UWB is shown to be the most suitable multiple access scheme to be adopted for UWB WSNs. It outperforms both the DS-UWB and OFDM-UWB schemes for all application environments and is the most robust and energy efficient. OFDM-UWB is the poorest performing whereas DS-UWB provides similar performance to TH-UWB below a specific threshold number of interfering nodes.