Research On Resource Management Algorithms Of Integrated Terrestrial-Satellite Networks

Integrated terrestrial-satellite networks integrate satellite network and terrestrial network by leveraging their respective advantages,and provide users with flexible network access services,and are expected to meet the requirements of various application scenarios and improve network performance.However,the dynamic changes of satellite network topology,the complex characteristics of inter-satellite and satellite-ground links,and the diversity of user requirements pose great challenges to the resource management in the integrated terrestrial-satellite network.Considering the characteristics of user services and data transmission modes,it is important to design effective resource management algorithms to improve network performance.This thesis studies the resource management algorithms in integrated terrestrial-satellite network,which specifically includes the following contents:Based on the overview of the system architecture,characteristics and application scenarios of the integrated terrestrial-satellite network,this thesis expounds the key technologies,analyzes and summarizes the research status of resource allocation algorithms,joint user association and route selection algorithms,joint user association and resource allocation algorithms in the integrated terrestrial-satellite network.The user association and route selection problem is studied for the uplink data transmission scenario of the integrated terrestrial-satellite network which consists of enhanced mobile broadband users(EUs)and massive machine type communication users(MUs).Considering the constraints of the traffic rate requirements,system available resources,and flow conservation constraints,the joint user association and route selection is formulated as an optimization problem which minimizes total system energy consumption.On account of various characteristics of EUs and MUs,this thesis first determines base station association mode for the two types of users,then proposes a delayed acceptance(DA)algorithm-based clustering strategy for MUs whereby certain EUs are chosen as the cluster heads of the MUs.Based on the obtained user association and clustering strategy,the route selection problem of EUs in satellite association mode is formulated as a constrained system energy consumption optimization problem.Since the optimization problem is a non-convex optimization problem,and is difficult to solve directly,the original problem is transformed into two sub-problems,i.e.,inter-satellite routing sub-problem and user association sub-problem.Considering the randomness of satellite links,inter-satellite routing sub-problem is formulated as a markov decision process(MDP)and solved by using Q-learning algorithm.Based on the obtained inter-satellite routing strategy,Kuhn-Munkres(K-M)algorithm is applied to solve the EU end-to-end association sub-problem.Simulation results demonstrate that the proposed data transmission scheme can effectively reduce energy consumption and improve system performance.The user association and resource allocation problem is studied for the downlink data transmission scenario of the integrated terrestrial-satellite network.The joint user association and resource allocation problem is formulated as the system utility function maximization problem under the constraints of user transmission requirements,network available resources and transmission limitations.The formulated optimization problem is a strong coupling problem,which is not easy to solve directly.Then,the original problem is transformed into two sub-problems,i.e.,power allocation sub-problem and user association sub-problem.To tackle the power allocation sub-problem,Lagrange partial relaxation method is used to relax discrete variables into continuous ones,and a new variable is introduced to eliminate the coupling relationship between optimization variables,so that the power distribution sub-problem is transformed into a convex optimization problem,and then Lagrange dual algorithm is used to solve it.Based on the obtained power allocation strategies,this thesis proposes a heuristic algorithm to solve the user association and resource allocation strategies in the case that the base station has sufficient time-frequency resources and insufficient time-frequency resources by comparing the relationship between the available time-frequency resources and the number of users.Finally,the effectiveness of the proposed algorithm is verified by MATLAB simulation software.