Research On Handover Alogrithm In UDN

From 2G to 3G ? 4G,up to the upcoming 5G,the development of mobile communication changes with each passing day,and gradually shows a pattern of diversification,isomerization and intelligence.With the popularity of various intelligent terminals,for 2020 and later,there will be an explosive growth of mobile data traffic,thus,ultra-dense network will become one of the key technology to solve the problem of data flow in the future 5G.These low-power nodes which are deployed in the macro cell in Ultra-Dense Networks,overlap the macro-area in the indoor and hot spots.While increasing the total capacity of the network,it makes the complexity of community boundaries increased,besides the irregular shape,if continue to use the previous cell switching algorithm,its inter-cell interaction control signaling load will grow exponentially with the increasment of cell density,which greatly increase the network control signaling load,causes more frequent switching,even the phenomenon of dropped calls,so it is difficult to ensure mobility performance.What's more,larger number of low-power nodes mean more power consumption,in this era of equal importance of efficiency and energy consumption,to meet the demands of green communication in energy saving and efficiency,a new switching algorithm is bound to appear.The entire handover process consists of three parts: measurement,handover decisions,and handover execution.The handover decisions phase is the most important part of the whole process of handover,and it is also the research focus of this thesis.This thesis introduces the technology of 5G ultra-dense network and its opportunities and challenges at first,analyzes the Basic concepts and principles of current mainstream cell handover technology,sums up the potential problems when applied to UDN,then speculates the research direction of the ultra-dense network handover algorithm.In addition,in the 5G ultra-dense network,the macro base station and the micro base station coexist,more overlap between the cell and the cell appears,handover decision becomes more complex.By analyzing and improving the traditional event B2 handover guideline,this thesis presents a handover algorithm based on the speed and multiple attribute.This algorithm firstly classifies the users by their velocity,and dynamically adjusts the retention thresholds,then uses the improved AHP and TOPSIS algorithm to perform multi-attribute weighting in the candidate base stations to judge the optimal handover network.The simulation shows that it reduces handover times and handover failure rate,besides,it improves the performance of the system.At last,according to the concept of green communication and the base station sleep technology,Multi-attribute handover algorithm based on base station sleep technology is proposed.This algorithm analyzes the sleep model of base station,derive the decision condition of micro base station sleeping algorithm.Through the multi-attribute decision of the handover decision to get the optimal sleep strategy and switching scheme,and then control the low loading base stations into the sleep state.In this way,the energy efficiency of the network is greatly improved with the premise of guaranteeing the quality of service of each user.