Research On Unified Wireless Access And Backhaul Technology

With the increasing demand for wireless communication data services,the fifth generation cellular system(5G)has put forward higher requirement for the capacity of mobile communication networks.In order to meet these requirement,a number of key technologies has been proposed,including ultra-dense network,small cell,Massive MIMO and millimeter wave technology,etc.Ultra-dense networks,as knows as heterogeneous networks,are a new kind of network architecture that includes macro cells and small cells that are widely deployed.Ultra-networks greatly expand the network capacity and improve the coverage range of the network.Small-cell technology is consider as one of the key technologies for mobile cellular communication networks in the future.The introduction of small-cell deployment in the mobile cellular networks can not only significantly increase network capacity,but also optimize network coverage more effectively,which provides users with better experience.Massive MIMO technology can effectively improve the transmission rate by utilizing the spatial gain of large-scale antenna array.Millimeter wave technology can greatly improve network capacity because of its wide availability of bandwidth.Firstly,this thesis introduces the small cell technology,including the classification and the architecture evolution of small cell.It also introduces the development of backhaul technologies and the evolution of backhaul architecture,as well as the challenges and expected solutions of joint design wireless access and backhaul.Then,aiming at a two-layer heterogeneous network with Massive MIMO and wireless backhaul technology,we study the joint optimization of spectrum allocation and user association in the network.The original optimization problem is decomposed into two sub-problems,which are optimized and then combined to obtain an efficient algorithm.The simulation results confirm that the algorithm has greatly improved the network capacity.Moreover,because channel estimation has great influence on network performance,we study the channel estimation problem in the heterogeneous network using millimeter wave technology as wireless access and backhaul technology finally.Aiming at the network,its system model and the sparsity of millimeter-wave Massive MIMO channel are analyzed.A structured compressive sensing-based channel estimation algorithm and another improved algorithm are studied.The simulation results show that the performance of the improved algorithm is better than that of other reference algorithms,and the performance of channel estimation is greatly improved.