Throughput Optimization Of Multi-hop Networks And Delay Optimization Of Full-duplex Networks

Due to a series of advantages such as high speed and low cost,the CSMA-based WLAN has been widely adopted in people's daily life.With the widespread deployment of CSMA wireless networks,researchers have been paid much attention to the analysis and optimization of CSMA networks.Full-duplex wireless communication technology is an emerging wireless communication technique,which can achieve almost twice the traditional network throughput.Thus,using full-duplex wireless communication technology to improve the network performance has also been attracting much interest from the community.The thesis devotes to the analysis and optimization of wireless networks.B ased on the throughput analysis of multi-hop wireless networks and the dela y analysis of full-duplex CSMA networks,we formulate the optimization model and obtain the optimization scheme,respectively.Simulations show the correctness and accuracy of the proposed scheme.Specifically,the main contributions of this paper are:(1)To improve the end-to-end throughputs of flows in multi-hop wireless networks,a joint optimization scheme Link-access-intensities Adjustable Multi-path Routing(LAMR)based on multi-path routing and CSMA protocol is proposed.LAMR can improve the end-to-end throughputs by jointly optimizing the flow assignment at the routing layer and the CSMA protocol settings at the MAC layer.First,we adopt the Ideal CSMA Network(ICN)model to analyze the link throughputs at the MAC layer,and then develop a Maximum System Throughput Model(MSTM)to characterize the impacts of path selection,rate assignment and protocol settings at the MAC layer on link throughputs in wireless multi-hop networks.Under the framework of optimization theory,the optimal multi-path flow assignment and the access intensity of each link can be obtained.Simulation results show that compared with the existing schemes,LAMR can improve the system throughput of 21.3%.(2)The thesis presents a simple and accurate model to analyze the queuing delay of packets in MAC layer in full-duplex WLANs.Based on the delay analysis,we then carry out the feasibility analysis.That is,for a given Quality of Service(Qo S)demand of the data streams,we can examine whether the network can afford the Qo S demand of the data streams.In addition,the performance of Qo S flows can be further optimized on the basis of the feasibility problem by adjusting the contention window settings.We propose an optimization model based on the user delay utility function,and use the interior point method and the gradient vector to solve the optimization problem.Simulation results show that,compared with the existing scheme s,the delay optimization design can significantly improve the delay performance of WLAN networks.