Energy-efficient heterogeneous antenna selection relaying in wireless body area networks

We present a multi-mode power amplifier (PA) set with an antenna selection mechanism in a body area relaying network for healthcare applications. The PA set of the relay node is designed to work in two modes where the RF switch utilized for antenna selection is located between the highly efficient narrowband PAs and a low-efficiency wideband PA supporting two heterogeneous networks. Our study shows that, unlike in the wideband PA mode, where antenna selection is always desirable for transmission reliability, antenna selection is not always preferred in the narrowband PA mode since in this mode, the PA needs to turn on and off constantly. Consequently, extra switch delay and energy consumption occur. To balance the tradeoff between the relay node´s energy efficiency and transmission reliability, both the switching probability between two modes and bounds on the probability of staying on the current antenna are analyzed. Numerical results are provided to corroborate the improved performance of the proposed architecture and the switch/stay mechanism.