Research On Edge Coverage Enhancement Scheme Based On Multi-RTP In 5G System

As an effective method to improve cell edge coverage,coordinated multi-point transmission(CoMP)scheme is considered as an important technical mean in the 5G system.The 3rd Generation Partnership Project(3GPP)considers the non-coherent joint transmission(NC-JT)scheme as an important candidate for 5G multiple-transmission/reception point(Multi-TRP)technology.At the same time,as a key technology for 5G,massive multiple-input multiple-output(MIMO)technology can significantly improve system spectral efficiency.In view of this,for the Multi-TRP scenario under massive MIMO,this thesis first designs a novel detection algorithm for the CoMP users,and proposes a hybrid multi-layer adaptive scheme in the Multi-TRP scenario,and then proposes an improved coordinated cluster selection scheme using coupling loss and a coordinated cluster selection scheme based on beam sweeping.The main contributions of this thesis are as follows:(1)At present,there are few researches on CoMP under massive MIMO,and most of them are limited to coherent joint transmission scheme,which usually requires sharing of channel information between coordinated base stations.This requirement is difficult to achieve for NC-JT scheme.Therefore,it is difficult to eliminate the interference in the coordinated cluster at the base station in the NC-JT scheme,and the traditional detection scheme cannot effectively eliminate the interference,either.This thesis proposes an enhanced minimum square error-inference rejection combining(MMSE-IRC)detection algorithm using channel information of the coordinated base stations for the CoMP users in the Multi-TRP NC-JT scenario.This algorithm can make full use of the channel information of the coordinated base stations to eliminate the strong interference of the base stations in the coordinated cluster and improve the throughput of the edge users.In the meantime,there are few researches on the multi-layer adaptive scheme in the Multi-TRP scenario,this thesis proposes a hybrid multi-layer adaptive scheme for the Multi-TRP scenario.Non-CoMP users use the channel singular value decomposition method to determine the number of transmission layers,and CoMP users use a hybrid multi-layer adaptive method based on singular value decomposition and capacity maximization criteria.This scheme maintains a balance between algorithm complexity and system performance.Simulation results show that the above schemes can effectively improve the performance of edge users in the Multi-TRP scheme.(2)The current research on coordinated cluster selection schemes lacks the characterization of small-scale channel information in the modeling of user state.Therefore,this thesis proposes an improved coordinated cluster selection scheme using coupling loss.Because the coupling loss comprehensively considers the changes of large-scale and small-scale channel information,this scheme improves the accuracy of adaptive selection.In addition,the precise directivity of beam formed by the massive antenna array is rarely considered in current research on coordinated cluster selection schemes.This thesis proposes a coordinated cluster selection scheme based on beam sweeping.Each user and each base station perform beam sweeping to select the best beam,and then the user selects an appropriate coordinated cluster according to the coupling loss after beam forming.Simulation results verifies that the above two coordinated cluster selection schemes can effectively distinguish edge users,and improve the probability of edge users selecting coordinated transmission and the throughput of edge users.