Research On Mobility-aware Transmit Power Control And Sparse Feedback Scheme In Ultra-dense Networks

Network densification has significant advantages in improving network capacity.At the same time,this kind of dynamic and dense network is facing the challenges of interference,mobility,backhaul links,and energy consumption,etc.For outdoor mobile scenarios,ultra-dense networks(UDNs)are tightly integrated into the overall wireless network architecture with mobility support.Therefore,new network design needs to adapt to the changes in traffic and scheduling more flexibly and quickly,and fully explore the characteristics and advantages of network densification and user mobility.The research direction of this dissertation is performance analysis of mobility-aware transmit power control and sparse feedback scheme in UDNs.Taking into account of the characteristics including the large scale of nodes and surging interference in UDNs as well as user's moving speed,the transmit power control scheme and sparse feedback scheme are designed according to user mobility and network characteristics so as to realize the transmission goal in mobile environment proposed by 5G and extend the application of UDNs in the outdoor scenarios.The main contributions involved in this dissertation are:First,this paper studies on mobility-aware transmit power control scheme.By analyzing the distribution of the distance between the user and its access base station,this dissertation puts forward two kinds of mobile-aware transmit power control schemes based on resource reservation using the predicted position in the moving process and analyzes the network outage probability and energy efficiency.Simulation results show that the proposed schemes succeed in improving the reliability and stability of the transmission as well as the energy efficiency.Second,this dissertation studies on mobility-aware sparse feedback scheme where feedback transmission delay and feedback waiting delay are analyzed separately and the impact of feedback channel interference and feedback overhead are considered on the feedback transmission delay.Base stations design zero-forcing precoding using the obtained outdated channel state information to realize inter-cell interference cancellation.The distributions of desired channel and interference channel after precoding are provided.Using the tool of stochastic geometry,the expressions of feedback delay and coverage probability are obtained.Numerical and simulation results provide the optimal feedback probability and measurement range under different user speed and base station density.