Bandwidth Dependence of the Propagation Channel in Circular Metallic BAN Environments

In this paper, the bandwidth dependence of the propagation channel for Body Area Networks (BANs) in circular metallic environments is addressed and models are proposed to evaluate the appropriate short-term fading margins that should be considered as a function of the system bandwidth. The deployment of BANs in metallic indoor environments, such as ships, factories, warehouses and other similar environments, involves additional challenges compared to other indoor environments due to the specific propagation effects in this type of environments (i.e., with strong reflections). No studies of this kind and for this type of environment can be found in literature, giving the motivation for this work. Bandwidth dependent values of delay spread are also presented and discussed. It is observed that for a system bandwidth up to 100 MHz the fading depth is composed of three main stages, with the transitions between these stages being associated with the system ability to discriminate arriving rays at the receiver. Average values of fading depth are 16.4, 13.2 and 11.0 dB for stages 1, 2 and 3, respectively, the difference between consecutive stages ranging between 2.2 to 3.2 dB. For a system bandwidth larger than 100 MHz, the fading depth decreases with an increasing system bandwidth, with an average decay rate close to 3 dB per 100 MHz bandwidth, being about 2 dB for system bandwidths above 400 MHz.