Research On Interference Management, User Association And Self-Organization Ntetwork Technologies In Heterogeneous Networks

In recent years, as the wide use of mobile devices such as smart phones, tablets and others, the network expands rapidly and the mobile data traffic increases exponentially. As a result, people are in great need of higher data rate. However, considering the limitations such as low spectrum efficiency and incomplete coverage, traditional cellular networks can not satisfy the demand of future networks. In this context, a new architecture namely heterogeneous network (HetNet) is proposed and attracting significant research interests. The HetNet comprises of a set of small cells overlaying the existing macrocells and brings in a hierarchical topology to the otherwise flat network architecture. Small cells regarded as the compensation to macrocells are deployed with different low power nodes (LPN) such as micro/pico/femto base stations. A heterogeneous architecture has advantages of improving system capacity, carrying part of data traffic and providing better coverage. Furthermore, it enables operator to offer higher quantity of wireless voice and data services.In this dissertation, interference management, user association and self-organization network technology are studied. Correspondingly, several innovative schemes are studied and the performance of the proposed schemes is verified by theoretical analysis and computer simulation methods. The main contributions of this dissertation are concluded as the following:1) In hybrid HetNet, we propose a dynamic resource allocation based interference management scheme.Firstly, according to the feature of the hybrid HetNet architecture, propose the problem of dynamic resource allocation based interference management. To reduce the load of the operator and management (O&M) entity, this problem is divided into two parts which are subcarrier allocation based coarse interference management and power control based subtle interference management.Secondly, for coarse interference management, O&M adopts an aggressive discrete stochastic approximation algorithm to find proper subcarriers for users. And meanwhile, the aim of minimizing the overall interference can be achieved. For the subtle interference management, LPN utilizes the Kalai-Smorodinsky bargaining based solution to allocate power to users. In addition, the local utility of LPN can be optimized. We also transform the vector optimization to the linear optimization while decreasing the complexity of the algorithm.Finally, simulation results verify the property of the proposed interference management mechanism through comparing ADS A and KSBS with existing schemes.2) Propose a user association scheme joint considering resource allocation for the distributed HetNet.Firstly, analyze the feature of the distributed HetNet and the available resource of the LPNs are described. Then derive the objection function from the minimal potential delay fairness function, based on which, the fairness between users can be guaranteed and the transmission data rate can be optimized.Secondly, construct the user association model jointly with resource allocation. Put forward the corresponding constraints related to saving the network power consumption while reducing the interference suffered by LPNs.Thirdly, propose the three step search method. To achieve the Pareto optimization, this method including three steps:First, search the supported non-dominated extreme points and the corresponding solutions; Then, search the supported non-dominated and unsupported non-dominated points and the corresponding solutions; Finally, select the optimal solution according to the system demand.Finally, verify the property of the proposed scheme.3) Considering multiple factors, we propose a resource configuration optimization mechanism for the self-organized HetNet.Firstly, construct a resource configuration optimization model taking energy efficiency, overall power consumption and connection stability of the network into account.Secondly, design the scheme which executes user association and power allocation separately. With the aim of exploiting the self-organization function of the base stations, propose a joint user association and resource allocation scheme. This scheme utilizes reinforcement learning to analyze the surrounding environment and has higher intelligence.Finally, various simulation results are utilized to verify the effectiveness of the proposed resource configuration strategy.