Balancing Hidden-node And Exposed-node Problems In Full-duplex CSMA Networks

With the upgrading of wireless communication systems,limited wireless spectrum resources have become increasingly prominent,and thus improving spectrum efficiency has attracted widespread attention from both the academic and the industry.Full-duplex(FD)technique can enable simultaneous transmission and reception in the same frequency band,which can effectively improve the spectrum efficiency and the future wireless network performance,and reduce the end-to-end communication delay.Compared with half-duplex(HD)technique,FD technique is expected to double the spectrum efficiency and the wireless system capacity.However,in FD enabled carrier-sense multiple-access(CSMA)networks,both hidden-node(HN)and exposed-node(EN)problems have negative impacts on the network performance,which still lack of in-depth research.Therefore,optimizing the performance of FD CSMA networks is an important topic with great research value.The goal of this thesis is to optimize the performance of FD CSMA networks by balancing HN and EN problems.The main contributions are summarized as follows:(1)The HD node can only send or receive signals in different time slots or different frequency bands,while the FD node can send and receive signals simultaneously in the same frequency band.As a result,the circular interference model and the circular carrier-sensing model used in HD networks are not applicable to FD networks.In order to analyze HN and EN problems in FD CSMA networks,this paper proposes bicircle interference model and bicircle carrier-sensing model to model the interference region and the carrier-sensing region of the FD network,respectively.(2)This paper effectively builds an analytical model based on stochastic geometry,and formally defines HN and EN problems in FD CSMA networks.Furthermore,the optimal carrier-sensing range in FD CSMA networks is obtained by minimizing the total probability of HN and EN problems,so as to optimize the performance of the FD CSMA network.(3)Simulation results verify the accuracy and validity of the probability of HN problem and the probability of EN problem in FD CSMA networks using the proposed analytical model,and evaluate the performance of FD CSMA networks,including the collision rate and the network throughput.Simulation results show that when the carrier-sensing range is close to the optimal carrier-sensing range obtained with the analytical model,the collision rate is significantly reduced and the network throughput reaches the maximum.