| Ultra Dense Network(UDN)is regarded as an important deployment pattern in 5G architecture,which deploys cells densely to enhance the coverage.UDN eliminates the high path loss caused by millimeter wave(mmWave)and improves the data rate in a large scale.Considering the flexibility,the random network(RN)based on random geometry attracts the attention of researchers.However,UDN introduces strong interference reducing the performance of cell-edge users especially in the RN.Multi-antenna transmission technology is a good choice to solve the strong interference and increase the system throughput and fairness.This thesis is focused on typical technologies of multi-antenna transmission-beamforming,coordinated multi-point(CoMP)and their applications in 5G UDN.The thesis introduces the background and key technologies in 5 G at first,then explains UDN,beamforming and CoMP in detail and makes in-depth study on the applications in resource allocation.The study of beamforming is based on Butler Matrix switched-beam system with the system model given.To decrease the intra-cell inter-beam interference and improve the data rate,this paper proposes a two-obj ective non-linear integer optimization with an interference attraction beam allocation scheme(IABA)for simplified implementation.The simulations show that compared with other schemes,IABA makes a better tradeoff between fairness and capacity.The study of CoMP is focused on the clustering in joint transmission especially for user-centric clustering algorithm.The paper builds the model of joint transmission and introduces an interactive CoMP with user-centric clustering based on load balancing(ICLB).ICLB implements load balancing dynamically via a three-phase interaction.The results show ICLB works much better on system fairness. |
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