Research On Transmission And Resource Management Schemes In Ultra-dense Network

With the development of communication technology and the popularity of mobile intelligent terminals,the demand for wireless data transmission has experienced dramatic growing.Meanwhile,the communicating mode also becomes plentiful.Communications between person and person can no longer meet the needs of the society,but that between person and thing,or even that between thing and thing are becoming more and more important,helping to build the network with low power consumption and high reliability.As a result,5G communication system puts forward high requirements for transmission rate,system delay,density of device and mobility.Ultra-Dense Network is one of the key technology to solve the problems involving network capacity and coverage.It deploys a large number of small cells with low cost and low power consumption to enhance the system capacity and to enlarge coverage.However,the new requirements come with new challenges.There are huge number of feedbacks which will lead to large system overhead and interference.So,the design of reasonable feedback scheme is one of the key research in the Ultra-Dense Network.Meanwhile,Ultra-Dense Network has the characteristics of high frequency and wide bandwidth,which is different from the conventional network and we need to re-design the frame structure to make it suitable for the new wireless transmission system.Besides,with a mass of overlapping low-power nodes deployed in Ultra-Dense Network randomly,conventional orthogonal resource allocation algorithm can't eliminate the interference effectively.We need to redesign the algorithm of interference elimination to improve network performance.In this thesis,the advantages and disadvantages of the current feedback technology is analyzed,and a feedback scheme based on network coding and cooperation between cells is proposed,with which the feedback message is transmitted without increasing thefeedback cost.Moreover,the frame structure of the Ultra-Dense Network redesigned.System parameters such as the subcarrier distance,cyclic prefix,etc.are optimized.And the effectiveness of the proposed scheme is verified by simulation results.According to the characteristics of the interference of Ultra-Dense Network,an interference alignment algorithm is adopted to eliminate interference.A clustering algorithm is proposed to cluster the cells so as to improve the network topological structure,which can still satisfy the demand of good feasibility and low signaling overheads.The network capacity is improved with the proposed clustering algorithm,which is verified in simulation results.