Derivation ofthe performance of the relay system and simulation analysis of the system under energy cooperation

Aiming at the problem of the energy hole caused by the frequent use of relay nodes in wireless sensor networks,a single relay system based on energy cooperation is proposed.The scheme assumes that the distribution position of the relay node obeys the Poisson point process, and that the source node and the relay node can harvest energy from the environment. When the source transmits a signal to the relay, some energy is also sent by the source to the relay. According to the battery storage state the source transmits its data to the destination either directly or cooperatively by the relay. Combined with the position of the relay node and the steady-state distribution of the battery, the system outage probability is derived. The optimization model is established to minimize the system consumed energy. The particle swarm algorithm is used to get the optimal system parameters. Simulation results verify the performance of the proposed model. It is also proved that energy cooperation can significantly reduce the energy loss in the communication link.