Research On Key SWIPT Technologies In Cognitive Relay Systems

In this paper,the key simultaneous wireless information and power transfer(SWIPT)technologies in cognitive relay systems are studied.As an effective technique to solve the deficiency of spectrum resources and improve the spectrum utilization ratio,cognitive radio(CR)combined with cooperative relay systems,which could effectively resist wireless fading,have attracted extensive attention among researchers.Besides,SWIPT as an effective technology to deal with communications of constrained-energy networks has appealed a wide range of researchers because it can transmit information and energy simultaneously.The combination of cognitive relay network and power transfer introduces a new idea and solution to current wireless communication systems.Firstly,this paper focus on SWIPT in cognitive half-duplex relay systems.This paper focus oin xwhether and how the quality of service(QoS)requirements can be guaranteed in half-duplex relay systems,where the available energy is extremely limited by power transf-er capability and the available spectrum is greatly restricted by primary networks.This research transmit signals with orthogonal frequency division multiplexing(OFDM).Thus,the joirnt power splitting ratio,subcarrier assignment and power allocation problem is formulated under the interference constraints and QoS requirements.In addition,in order to maximize the capacity of the secondary network,an optimal power splitting and resource allocation scheme is proposed based on dual decomposition as well as time sharing conditions.Simulation results show that the proposed scheme can perfectly satisfy the QoS requirements in spite of limited energy and spectrum,and outperforms conventional methods in terms of capacity and QoS satisfaction.In addition,this paper pay attentions to SWIPT in cognitive full-duplex relay systems.Currently,most research is using half-duplex relay.However,full-duplex relays,which can make full use of spectrum with transmitting and receiving signal at the same time,is worth study.This paper proposed a relay protocol and a new self-recycling SWIPT-relay transceiver architecture,with which enable the so-called self-energy recycling,without self-interference cancelation.In order to maximize the capacity of the secondary network under limited power and interference,this paper analyzes and compares the performance of the proposed protocols,and study SWIPT in cognitive full-duplex relay systems,with convex optimization and sub-gradient.