| In recent years, technology advances have made possible the deployment of tiny, low-cost, low-power devices, which are capable of sensing, processing, and communicating. The energy consumption of these sensors thus becomes a critical issue due to their wireless characteristic. One of the next generation radio technology, Ultra-Wideband (UWB) technology has started to be adopted in some wireless sensor networks (WSNs). Due to the lack of unified specification of UWB, study in this field is difficult. Recently, there has been work on reducing the energy consumption of UWB-based WSNs. The effects of some factors, such as node mobility and topology, have been considered. In this work, we investigate the energy consumption of UWB-based WSNs, considering the joint effects of the physical, MAC and network layers. Two major UWB technologies have been studied, i.e., MB-OFDMUWB and DS-UWB. We adopt the Multi-channel MAC protocol (MMAC) in the MAC layer and Minimum Transmission Energy (MTE) routing protocol in the network layer. In MMAC, a special data structure called Preferable Channel List (PCL) is introduced in the channel selection procedure. The preferred channel for the data transmission is selected based on its priority status. At the same time, two new packet types, ATIM-ACK and ATIM-RES are introduced during the ATIM window for channel negotiation. A Markov chain is used to model the back-off window size. Based on the parameters from the three layers, we define and derive the energy consumption of each node. Numerical and simulation results are presented to demonstrate the effects of the parameters from the physical, MAC and network layers on the energy consumption, in terms of number of nodes, number of channels, amplifier power density, packet body size, and minimum contention window size. |
