Research On Wireless Resource Management And Scheduling Policy For Next-Generation Mobile Communications

The global cellular communication network was one of electrical engineering’s crowning achievements, reliably connecting over three quarters of the planet’s popula-tion, virtually everywhere where people were. As the development of wireless commu-nications, the growing numbers of wireless users and their ever growing requirements on the quality of services had been pushing the wireless communication system to search for more resources to consume. While on the other hand, the increasing scarcity of resources in communications had been more serious than ever. Under such dilemma, to further improve the performance of the mobile communication system, promising wireless resource management schemes and resource scheduling strategies were needed for the optimization of the existing communication resource utilization and also the expansion of the available resource space.Based on three typical scenarios, the thesis had been focusing on the resource management schemes and scheduling policies in the wireless mobile communication networks. The main purposes of the research were to supply the design and develop-ment of the next generation communication systems with theoretical guidance, to offer technical solutions for the performance improvement of mobile communication systems and to give evaluations on the practical resource management and user scheduling al-gorithms for the specific mobile communication systems. The main contributions of the thesis were illustrated separately as follows●Research on Wireless Resource Management Schemes in Cooperative Multi-Cell OFDMA Networks. In the cooperative multi-cell OFDMA net-works, the thesis proposed a joint wireless resource management and inter-cell co-operative link selection schemes in the context of a constrained backhaul network. An intra-cell wireless resource management strategy based on the Hungarian Algo-rithm was proposed first, which had not only maximized the average throughput of the multi-cell network but also raised the fairness among the intra-cell users. And then, under the capacity constraint of the backhaul network, an inter-cell coopera-tive link selection scheme was proposed based on pricing considerations. The users rates were brought up by the proposed schemes due to the inter-cell interference cancellation, in the mean time, the demands for capacity on the backhaul network was reduced effectively. Simulation results illustrated that the proposed schemes had performance advantages in the point of user fairness, average throughput of the network and relieving the communication pressures on the backhaul network. On the basis of the channel state information and user date sharing across the cooper-ative multi-cell network, the prosed schemes in this thesis had managed to obtain the maximized inter-cell cooperative gain with the minimized signaling overhead of the network.●Research on Power Control and User Scheduling Strategies in Coordi-nated Multi-Cell OFDMA Networks. In the coordinated multi-cell OFDMA networks, the thesis proposed two different power control and user scheduling schemes based on different degrees of channel state information sharing for inter-cell interference coordination. Through the multi-cell OFDMA network model, the net-work capacity maximization problem was formulated with multi-dimensional vari-ables for the purpose of inter-cell interference coordination. Accordingly, two solu-tions with different access to the network channel state information were proposed, and one of them was a centralized joint scheme while the other was a dynamically distributed scheme. For the centralized scheme, the the three-dimensional opti-mization problem was transformed into a two-dimensional problem by the help of mappings among the variables first.Based on the global channel state information of the network, the original combinatorial optimization problem was decomposed into a continuous optimization problem of power control and a discrete optimiza-tion problem of user scheduling. With the help the convex optimization theory, the proposed joint power control and user scheduling algorithm was a double iteration based scheme which was the near optimal solution to the proposed problem for any precision. For the distributed scheme, under the circumstances of local chan-nel stated information only, the original three-dimensional optimization problem was reformulated as a multi-stage decision problem in the discrete time dynamic system through dynamic programming theory. Based on the so-called Bellman Principle of Optimality in dynamic programming, a distributed power control and user scheduling algorithm was prosed to make the decision on the optimal control strategy of the formulated dynamic system. On the basis of the numerical results, the thesis had posed some analysis and evaluations on the proposed schemes in dif-ferent ways under both correlated channel assumptions and independent channel assumptions. The related research results had proved the performance advantages and robustness of the two proposed schemes.●Research on Dynamic Cell Association and User Scheduling in Car-rier Aggregated HetNets. In the carrier aggregated multi-tier heterogeneous networks, the thesis proposed two dynamic cell association and user scheduling schemes for the traffic load balancing along with the ergodic rates maximization problem. Under the single flow carrier aggregation scenario, a stochastic control based cell association scheme was designed, while the other joint cell association scheme was announced under multi-flow carrier aggregation in the multi-tier het-erogeneous networks. Firstly, the formulate ergodic rates maximization problem was discretized into a dynamic multi-decision problem through stochastic control and dynamic programming theory. The multi-decision problem was then broken into multiple single decision problems to fulfill the optimal control process, which was proposed as the single-flow based dynamic cell association and user scheduling algorithm. Secondly, the original rates maximization problem was relaxed into a convex optimization problem with multi-flow carrier aggregation possibilities. The joint cell association and user scheduling algorithm was acquired through dual decomposition. The numerical results and performance analysis were carried out under different carrier deployments for both single flow and multi-flow based cell association and user scheduling schemes, through which the thesis had proved the advantages of the proposed schemes in traffic load balancing and network ergodic rates maximization.