Power Control For Dual Connectivity In LTE-Advanced System

Mobile data traffic has been predicted to grow exponentially in the next several years due to recent increased penetration of smart phones,tablets and various other mobile devices running a vast array of mobile applications including video applications.With the rapid growth of mobile traffic demand,a promising approach to relieve cellular network congestion is to offload users' traffic to small-cell networks.Dual connectivity is envisioned as a promising technology to significantly increase the per-user throughput as well as to achieve enhanced mobility robustness.Therefore,the emergence of small cell enhancement with dual connectivity is great significance in the LTE-Advanced system.Firstly,the technology of dual connectivity which is one of the small cell enhancement technologies has been introduced in this thesis.Based on this background,the challenges as well as problems of dual connectivity via non-ideal backhaul have been analyzed,the following challenges are expected: mobility robustness,UL/DL imbalance between macro and small cells,increased signaling load due to frequent handover,difficult to improve per-user throughput by utilizing radio resources in more than one eNB,network planning and configuration effort.The architectures as well as protocols of control plane and user plane of dual connectivity are also represented in this thesis.Secondly,this thesis analyzes the potential problems in the technology of dual connectivity due to the existence of non-ideal backhaul,and introduces the uplink power control in 3GPP Release 14 in detail.It studies differences of power control between dual connectivity and carrier aggregation,as well as challenges to the uplink power control mechanism for both the eNBs and the UE when configured with dual connectivity.In order to solve this problem,an intelligent scheme for uplink power control of dual connectivity is required.On this basis,this thesis analyzes the existing three kinds of uplink power allocation algorithms for dual connectivity,including equal distribution algorithm,semi-static allocation algorithm and distributed algorithm.Finally,an improved algorithm,semi-static power allocation algorithm 2 and distributed power allocation algorithm 2 for semi-static algorithm and distributed algorithm are given respectively.Theoretical analysis and simulation results show that the two improved algorithms can increase the throughput of the system.The distributed algorithm 2 can save energy and improve the power utilization rate greatly.