Research On New Relay Cooperation Strategy In Wireless Communication System

In the era of rapid development of emerging industries and modern technologies,information exchange has become more and more important.As one of the main ways of information transmission today,wireless communication technology has gradually penetrated into all aspects of human life and played an irreplaceable role.Cooperative communication,as a special communication mode in wireless communication systems,is widely used in current wireless communication networks.As the core technology in cooperative communication,relay technology can effectively solve the attenuation problem in the signal transmission process,so that the radiation range of the source signal is wider,thus covering more users and greatly improving the transmission performance of the system.Based on cooperative relay,this paper studies two communication models with new relay cooperation strategies,and analyzes and studies some related problems for each model.Firstly,this paper proposes a hybrid decode forward(DF)and amplify forward(AF)relay forwarding strategy based on opportunistic layered multicast(HDAF-OLM),which is aimed at multicast scenarios with multi-user and multi-relay.This strategy applies non-orthogonal multiple access technology,hybrid DF&AF relay forwarding strategy and layered multicast transmission technology to form a complete signal transmission scheme,which can not only meet basic transmission requirements,but also fully exploit the advantages of each technology.In addition,combined with this new scheme,this part studies the multicast partition analysis method for the transmission scheme.By this method,we can obtain the maximum transmission rates of the two signals in the scheme under the condition of fixing the number of users in different groups.In this chapter,we also develop a series of performance evaluation indicators for this transmission strategy,and compares these metrics by simulation.The results show that compared with the traditional multicast scheme,the proposed HDAF-OLM scheme combined with multicast partition analysis can achieve a larger maximum transmission rate,a larger system average throughput and a lower system delay.At the same time,HDAF-OLM can achieve a larger total system capacity than traditional transmission schemes.In addition,this paper also discusses a multiple input-single output(MISO)four-node cooperative communication model,in which the relay node can use the power splitting-based relaying(PSR)protocol to collect energy from the radio frequency signal,and can adaptively perform DF or AF signal forwarding protocols.The entire system performs signal transmission based on a similar non-orthogonal multiple access(NOMA)uplink transmission.And the user decodes the two signals based on successive interference cancellation(SIC)technology.This paper proposes the optimization problem of energy acquisition parameters and the optimization of power allocation for the energy efficiency of the system.Each problem is divided into two sub-problems according to the different relay forwarding protocols.This paper combines Karush-Kuhn-Tucher(KKT)conditions and utilizes multiple optimization algorithms and analysis solve two optimization problems.In addition,this paper also uses simulation to verify the above mathematical analysis and algorithm,and observe the influence of different parameters on the system performance.