Research On Access And Backhaul Technology Of 5G Millimeter Wave Network

With the continuous emergence of massive wireless terminals and diversified application requirements,the demands on wireless mobile communication system are increased correspondingly,for example,much larger required bandwidth,more reliable communication connection,higher communication efficiency and lower system energy consumption.There is a great pressure confronted by the existing mobile communication system.Therefore,the development and research of the fifth generation mobile communication system(5G)have been started within the industry and the academia.Millimeter wave integrated access and backhual network(mm Wave IABN)is an important part of 5G mobile communication system.However,since the millimeter wave transmission is facing at the high path loss and obstructions sensitity problems,great technical challenges appear in mm Wave IABN in terms of user access,traffic backhaul and joint optimization between access and backhaul.Therefore,the technical challenges of mm Wave IABN are investigated in the dissertation,and the main contributions are as follows:1.To reduce the power consumption under the consideration of user access robustness,a greedy based algorithm with low power and user multi-associations(GALUM)is proposed,where the power consumption is reduced while access robustness is satisfied.Firstly,the problem of user multi-associations is formulated as an integer programming problem for the minimization of the number of the small cell stations under the consideration of the minimization of the power consumption.Secondly,the formulated optimization problem is proved as an NP-hard problem through transforming the problem as minimum dominating set problem,which has been proved as an NP-hard problem and the optimization solution is intractable to be obtained in polynomial time.Thirdly,the GALUM is proposed,where the excess degree of the network is defined and used to select and add the active small cell stations,and then the maximum flow of the network is calculated to ensure the capacity constraints between the access links and backhaul links.Finally,it is shown in the simulation results that the number of small cell stations is reduced in the proposed GALUM under the condition that the robustness of user access is guaranteed.As a result,the total power consumption of the network is reduced correspondingly.2.To improve the backhaul throughput of the mm Wave IABN,a novel remaining bandwidth based multi-paths routing(RBMR)protocol is designed,where the backhaul throughput is improved substantially,the routing control overhead and network packet loss rate are reduced simultaneously.Firstly,the remaining bandwidth is defined as the maximum achievable transmission rate on the backhaul channel of millimeter wave small cell station.Secondly,specific signaling processes are designed for the three dominant parts of RBMR,i.e.,bandwidth information interaction between neighbor nodes,source routing based multi-paths routing discovery and multi-paths routing maintenance.The source routing based multi-paths routing discovery process is composed of three parts,i.e.,the sub-processes of routing packet processing in source node,intermediate node and destination node,respectively.The multi-paths routing maintenance process is composed of sub-processes for the path deletion and activation.Thirdly,the upper bound of the number of average backhaul paths for each node is analyszed and derived theoretically,and the analysis results are consistent with the Monte Carlo simulation results.Finally,it is shown in the simulation results that the network backhaul throughput is enhanced,while the routing control overhead and network packet loss rate are reduced in the proposed RBMR.3.To solve the problem of low spatial multiplexing of the mm Wave IABN,a Qo Sguaranteed based joint optimization of resource allocation and concurrent scheduling(QJO-RACS)is proposed,where the spatial multiplexing gain and network throughput are effectively improved.Firstly,an enhanced co-channel reverse time division duplexing(ECR-TDD)frame is designed to improve the network spatial multiplexing gain.Secondly,the joint optimization of concurrent transmission scheduling and resource allocation between access and backhaul is formulated as a mixed integer nonlinear programming(MINLP)problem.Thirdly,the QJO-RACS is proposed,which is composed of three parts,i.e.,the interference threshold based construction of conflict graph,the maximum independent set based solution of concurrent scheduling and the spectrum efficiency based resource allocation between access and backhaul.Fourthly,the selection impact of the interference thresholds on system performance is theoretically analyzed and derived,and the theoretical analysises are consistent with the simulation results.Finally,it is shown in the simulation results that the number of concurrent flows transmitted successfully,with which spatial multiplexing gain is characterized,and network throughput are improved substantially in the proposed QJO-RACS.4.To improve the access and backhaul throughput of the mm Wave IABN,a condition-decomposition-based joint optimization of user association and resource allocation(CJO-UARA)between access and backhaul is proposed,where the network throughput can be effectively improved.Firstly,the association strategy between UE and mm Wave small cell station and the resource allocation strategy between access link and backhaul link are jointly formulated as a combinatorial non-convex and non-linear optimization problem(CNNOP),where the network throughput of mm Wave IABN is maximized.Secondly,the CJO-UARA is proposed to solve the formulated problom,which is divided into two sub-problems.The objective of the first sub-problem is to determine the user association strategy to maximize of the user access rate under the condition that the access rate and the backhaul rate are equal.The objective of the second sub-problem is to allocate the resource between access link and backhaul link to maximize the network throughput under the consideration of the user association strategy obtained with the first sub-problem.Thirdly,the immune optimization algorithm based user association is designed for the first sub-problem,and an optimal solution of user association strategy is obtained.Then a statistical sequence based extremum optimization algorithm is proposed for the second sub-problem and the optimal solution of the resource allocation strategy between the access and and backhaul is obtained.Finally,it is shown in the simulation results that the access throughput,backhaul throughput and end-to-end throughput are improved prominently in the proposed CJO-UARA.