Distributed Relay Selection Protocols for Simultaneous Wireless   Information and Power Transfer
  Harvesting energy from the radio-frequency (RF) signal is an exciting solution to replenish energy in energy-constrained wireless networks. In this paper, an amplify-and-forward (AF) based wireless relay network is considered, where the relay nodes need to harvest energy from the source's RF signal to forward information to the destination. To improve the performance of information transmission, we propose two distributed relay selection protocols, Maximum Harvested Energy (MHE) protocol and Maximum Signal-to-Noise Ratio (MSNR) protocol. Then, we derive the outage probabilities of the system with our proposed relay selection protocols and prove that the proposed selection protocols indeed can improve the system performances and the MSNR protocol outperforms the MHE protocol. Simulation results verify the analysis and theorems. In addition, the effects of key system parameters are also investigated via simulations. 
Jing Yan, Chao Zhang, Zhenzhen Gao
cs.IT math.IT