Study On Wireless Resource Management Strategies In Cooperative Communication Networks

With the deployment of the fifth generation(5G)wireless communication networks on a global scale,beyond--5G(B5G)wireless communication networks have gradually become the foreword research topic of the industry and academia.B5 G wireless com-munication networks are facing many challenges,since the explosive growth of mobile data traffic and the emergence of various new application scenarios.Specifically,future mobile communication aims to adopt more efficient transmission technology to enhance the spectrum efficiency(SE)and energy efficiency(EE).Moreover,with the rapid devel-opment of internet of things(Io Ts)and machine-type-communication(MTC),the number of mobile intelligent devices is growing rapidly,and therefore efficient computation of-floading is particularly important for the energy-constrained mobile intelligent devices.In addition,along with the emergence of new materials such as intelligent reflecting sur-face(IRS),the future mobile communication will achieve sustainable throughput capacity growth with low cost,low complexity,and low energy consumption.In order to meet the various new mobile services under limited wireless resources,efficient resource manage-ment has become the research direction of B5 G wireless communication networks.B5G wireless networks are still in the exploratory stage,so how to ensure the net-work quality of service(Qo S),EE,delay and implementation cost is its major issue to be addressed.In recent years,cooperative communication has become an important candi-date technology to solve the above problems by efficiently mining the diversity gain and efficiency improvement of network nodes.Therefore,focusing on the various require-ments of B5 G mobile communication,this thesis uses the cooperative communication to improve the energy efficiency of the system,reduce the delay and the implementation cost.We conduct in-depth research on the cooperative communication networks with different requirements from three aspects: system model,access scheme design,and performance analysis.The main research contents and contributions of this thesis are summarized as follows.Firstly,we explore the impact of the potential cooperative behavior of the base station(BS)and the demand side on the system EE and quality of experience(Qo E).The coop-erative communication mode between the BS and the demand side can be constructed by defining the demand-side coordinated EE(DSC-EE)function.The system model is formulated to maximize the DSC-EE by power allocation under constraints of maximum transmit power and the expected rate of users.We propose a local optimal transmission scheme by transforming the original non-convex problem into two tractable subproblems.The analysis illustrates that the system EE can be improved and a higher implementation level of on-demand power allocation can be achieved when fully considering the cooper-ative behavior between the BS and the demand side.Secondly,we study the average EE issue of cooperative communication in Het Nets.Based on the social trust network,the spectrum-power trading mechanism between users is established.Considering the mobility of users,a social-awareness aided adaptive access scheme is proposed to maximize the average EE of the system.The analysis results reveals that the tradeoff between the average EE and the average convergece time.In addition,the analysis results show that,benefiting from the advantages of social trust,the social-awareness aided adaptive access scheme can significantly improve the average EE of the system and enhance the security of data transmission.Thirdly,the weighted delay and energy consumption minimization problem of device-to-device(D2D)cooperative mobile edege computing(MEC)system is studied.Based on the status of mobile intelligent devices and the social trust relationship between users,four computation offloading modes are established.Accordingly,the system model is modeled to minimize the average weighted delay and energy consumption by jointly considering the computation offloading model dynamic selection,transmit power and computing power allocation under the constraint of computation execution delay.Our analysis shows that the average weighted delay and energy consumption of the system can be asymptotically stable via local policies.Finally,based on the new carrier of low-cost intelligent reflecting surface(IRS),com-bined with the scenario of point-to-point(P2P)communication,a modular IRS is proposed to solve the problem of balancing the dimension of IRS and Qo E.Accordingly,focusing on modular IRS-aided two-hop cooperative communications,we formulate the SINR-based max-min problem from the perspective of joint triggered module subset identification,transmit power allocation,and passive beamforming under constraints of the module size,maximum transmit power,and IRS phase shifts.The optimal triggered module subset,transmission scheme designa and dimension reduction passive beamforming can be ob-tained by relaxing the original NP-hard problem into a second-order cone problem.The analysis results show that the SINR of the P2 P network can be improved significantly by introducing the modular IRS,and reveals the tradeoff between the achievable data rate and the total power consumption.