The Research On Performance Enhancing Techniques In Ultra Dense Network

In recent years,with the popularity of the smart mobile terminals,the 5th Generation mobile communication system(5G)arises at the historic moment.As the nuclear technology to keep the data bulk grow with thousand-fold speed in 5G,the ultra-dense network(UDN)already attracted extensive attention.At the same time,UDN is struggling with intensifying problems:First of all,from the perspective of modulation technology,UDN still uses the traditional macro-cellular network modulation mode,which only supports 64QAM.For the ultra-dense network with good channel conditions,this modulation mode cannot take full advantage of channel resource,therefore,there is a great possibility to introduce higher order modulation into ultra-dense network.Secondly,from the perspective of scheduling technology,the current scheduling algorithm in ultra-dense network is the same as the classic scheduling algorithm in LTE system,the huge difference between the ultra-dense network and the traditional macro-cellular network provides space for the design of the new scheduling technology in UDN.In addition,due to the shrinking of the base station coverage,base station switch caused by the movement of UE become more frequent.Besides,interference undulation will be much stronger because of the traffic emergency.At the same time,the intensive deployment of base stations will increase energy consumption and system interference.Aim at the above shortcomings in UDN,this paper studies three technologies used to enhance the performance of ultra-dense network.And simulation platform is constructed to verify the performance of there kinds of enhancement technology.The main tasks of this project are summarized as follows:1)By referring to the 2a scenario defined in 3GPP R12,the outdoor UDN link level and system level simulation platforms are constructed.2)In terms of modulation mode,this paper proves the feasibility of using 256QAM higher order modulation technique in outdoor ultra-dense network.First of all,we conclude the SINR threshold that 256 QAM is superior to other modulation way by link level simulation,then it is verified that 256 QAM is available in outdoor UDN scenario with the assistance of Small cell on/off mechanism by system level simulation.For the implementation of 256QAM modulation.We designed the relevant CQI and MCS form.Finally,we conclude that 256QAM can bring many benefits through system level simulation and comparison.3)In terms of scheduling technology,the scheduling technology based on channel detection is proposed and implemented in system level simulation platform.With simulation comparison,we conclude that scheduling technology based on channel detection perform better than the LTE scheduling ways when the system load is light.4)In terms of virtualization technology,The user-centric cell virtualization technology is designed in this project to solve the problems of frequent base station switch caused by the movement of UE,stronger interference undulation because of the traffic emergency,huge energy consumption and serious interference.In the process of implementation,a number of process rules are proposed,which includes hybrid control mechanism,the criteria for the construction of virtual cell,four different Master TP selection and handover criteria,joining and deleting of nodes in virtual cell,the criteria of slave TP handover,and the criteria of user mobility management.System level simulation result show that the user-centric cell virtualization technology can bring benefit for system performance.At the very last,user-centric cell virtualization technology is combined with Small cell on/off mechanism and the CoMP mechanism.With the help of cell virtualization,the silence and coordination of base station can be performed in a unified way to reduce interference and save energy consumption.