Energy efficiency analysis of IEEE 802.15.6 based wireless body area networks in scheduled access mode

This paper investigates the energy efficiency of IEEE 802.15.6 based wireless body area networks in the scheduled access mode. We assume that the hub operates in beacon mode with superframes and the nodes obtain scheduled allocation intervals consisting of finite number of allocation slots from the hub. In this paper, first of all, we present analytical models to compute the energy efficiency of the network for various scheduled allocation and acknowledgement policies assuming ideal channel conditions. The numerical and simulation results show that energy efficiency can be improved by (1) increasing the number of uploads in an active superframe, (2) increasing the payload size, (3) adopting block acknowledgement policy instead of immediate acknowledgement policy or (4) by decreasing the periodicity of allocations. We then present an analytical model to evaluate the energy efficiency in the presence of channel error. An approximate analytical solution for optimal frame size that maximize the energy efficiency of the network in error prone channel is obtained. For each node, we also provide analytical expression for the optimal allocation interval per superframe that maximize the energy efficiency of the network. Through extensive simulation studies, we establish that, in an error prone channel, the energy efficiency can be improved if the nodes make use of computed optimal frame size and optimal allocation interval for the uplink data transfer.