The Research Of Interference Coordination And Precoding Technology Towards 5G System

In recent years, the increasing of intelligent mobile terminals, such as smart phones and wireless devices has boost a domestic demand for data and multimedia services anytime and anywhere. The popularization of traffic-intensive applications including high-definition video, 3-D visualization, virtual reality, wearable devices and cloud computing defines a new era of mobile communications. And the fifth-generation mobile communications system (5G) will emerge to offer large capacity and ubiquitous coverage, at the same time to meet the requirements of higher rate, lower latency and higher spectrum efficiency. Different from 3G/4G,5G network pays more attention to the user experience, which requires a paradigm shift in all aspects of mobile networks. Ultra-dense networks(UDN) has been recognized as one of the key enabling technologies to meet the explosive increase of data traffic in 5G wireless system. By increasing the density of small stations (including the femtocell, picocell,relay and RRHs) in hot spots, the UDN can eliminate blind spot and improve the performance by shortening the distance between base stations and terminals. However, due to the dense deployment of Aps, the interference, the main factors of restricting the growth of system capacity,makes the resource management and interference suppression a challenging problem. Coordinated multipoint (CoMP) is a promising technique for improving the performance of cell edge users, where a number of base stations (BSs) form a cluster to jointly process signals to the users within the cluster. Dynamic clustering and intercluster co-ordination were proposed to mitigate interference to users at cluster edges.To further enhance the performance of cluster-edge users, user-centric overlapped clustering is more effective in providing multiuser MIMO and intercluster CoMP from multiple BSs belonging to different clusters. Based on this, in this paper, we focus on the UDN and make some research of clustering strategy and precoding strategy in coordinated multiple point transmission. Secondly, to lead a better user experience and handover the congestion of users, we also made some research on the precoding optimization to realize the optimal delay.First, to overcome the interference problem in the UDN, we proposed a user-centric clustering algorithm based on the local precoding scheme where we eliminated the interference by user selection and reduced the backhaul by optimal coordinated range. Secondly, in this paper, we proposed a method of resource allocation based on delay optimization in cloud random access network (C-RAN) where the control actions were assumed to be a function of the instantaneous channel state information as well as the queue state information. Semidefinite relaxation algorithm and convex and consave procesure (CCP) algorithm were introduced to solve this optimization problem. Simulation results showed that our algorithm has achieved good performance with respect to the reduction in energy consumption and the improvement of capacity.