Research On Energy Efficiency Of Simultaneous Wireless Information And Power Transfer Full-Duplex Relay Networks

The combination of full-duplex technology and cooperative relay improves the network throughput and transmission range and makes the technology widely used in various communication networks.Although the full-duplex cooperative relay technology improves the spectral efficiency of the full-duplex relay network to a certain extent,the problems of high energy consumption and low energy efficiency still exist.So how to reduce the full-duplex energy consumption of relay network to improve the energy efficiency of the network is particularly important.To this end,this thesis conducts an in-depth study on the energy efficiency of full-duplex relay networks,including the energy efficiency optimization of full-duplex decode-and-forward relay network based on Simultaneous Wireless Information and Power Transfer(SWIPT),full-duplex cognitive relay network with nonlinear energy harvesting,and SWIPT full-duplex cognitive relay network with imperfect channel state information,so as to further improve the energy efficiency and other performance of full-duplex relay network,and promotes the development of high-quality green communication.In this paper the research content and contributions are as follows:1.An energy efficiency optimization strategy for SWIPT full-duplex decode-and-forward relay network is proposed.In this strategy,SWIPT technology is adopted for relay nodes,and the transmission time in the channel is considered to construct the energy efficiency optimization problem.Then,aiming at maximizing the energy efficiency,the forwarding power of the relay node is calculated under linear energy harvesting,and the transmission power of the source and destination node is calculated under the requirement of ensuring the transmission information.Finally,the optimal expression of network energy efficiency is derived by calculating the transmission time and power segmentation factor under the condition that the signal-to-noise ratio of decode-and-forward protocol is equal.The simulation show that the energy efficiency of the proposed bidirectional SWIPT full-duplex decode-and-forward relay network is better than that of unidirectional SWIPT full-duplex relay network and bidirectional full-duplex decoded-and-forward,amplify-and-forward relay network.2.Nonlinear energy harvesting and cognitive radio technology are considered simultaneously in full-duplex relay networks,and a joint optimization method based on maximizing network energy efficiency is proposed.Firstly,the distributed optimization method is used to solve the transmission power of sub-user and cognitive relay under the fixed transmission time and power segmentation factor,and by ensuring the transmission information of the channel.Then the power is substituted into the original energy efficiency optimization problem,and the optimization problem is proved to be convex by using Hessian.Finally,the transmission time and power splitting factor can be obtained by using the first-order partial derivative to be zero,and then the optimal expression of energy efficiency can be obtained.The simulation results show that the proposed joint optimization method can effectively improve the network energy efficiency under the condition of sub-user security transmission information.At the same time,it is verified that the energy efficiency of nonlinear energy harvesting network is lower than that of linear energy harvesting network under the same optimization method,which is consistent with the actual situation.3.A multi-factor joint optimization method for energy efficiency of SWIPT full-duplex cognitive relay networks under imperfect channel state information is proposed.Firstly,the channel estimation error and the energy consumption of each node are analyzed to construct the energy efficiency optimization problem.Then the transmission power of sub-user and cognitive relay is solved under the requirement of ensuring the transmission information of channel.Finally,the power is brought into the energy efficiency optimization problem of the construction,and the Hessian matrix is used to optimize the transmission time and power segmentation factor,furthermore,then the optimal expression of energy efficiency can be obtained.The simulation results show that the existence of channel estimation error will affect the energy efficiency of the network,and the larger the value of channel estimation error,the lower the energy efficiency of the network.The network energy efficiency under linear and nonlinear energy harvesting is compared and analyzed,and the effectiveness of the proposed joint optimization method under the two energy harvesting methods are verified.It is also verified that the energy efficiency of the network can be maximized by symmetric information transmission.