Handoff In Heterogeneous Radio Access Networks Of 5G

In order to cope with the customized user demands generated by diverse application scenarios,the future wireless network must be a heterogeneous network with the mixture of multiple communication technologies.However,the traditional,rigid and closed architecture of radio access network(RAN)is inefficient and incapable for rapidly changing scenarios,requirements,and convergence technologies.Therefore,the architecture of future heterogeneous network is expected to be more open,flexible and customizable.In future heterogeneous wireless networks,for the handoff of mobile users,the traditional handoff scheme cannot meet the consistency experience of customized services during the handoff procedure.However,the introduction of network slicing technology can satisfy the users' requirements for different services by customizing different RAN slices,so the heterogeneous handoff scheme based on RAN slicing remains to be studied.Meanwhile,an efficient heterogeneous wireless network selection algorithm is also one of the decisive factors for ensuring the user's experience during handoff procedure.How to guarantee the quality of service(Qo S)requirements and enhance the system performance are still to be exploited.In terms of the above two issues,this thesis is devoted to the following studies.This thesis studies a hierarchical and heterogeneous wireless network based on control and data separation,and designs a heterogeneous wireless network handoff scheme based on RAN slicing.Employing key technologies such as Software Defined Network(SDN),Network Function Virtualization(NFV),and network slicing,we design the central controller and RAN slice of the LTE/WLAN network in detail.Moreover,we show the specific implementation process of the designed handoff scheme.Finally,we build the prototype platform by combining software with hardware.Experimental results show the feasibility of the designed handoff scheme,and prove the characteristics of the hierarchical and heterogeneous wireless network such as centralized control,flexible reconfiguration and customization.In order to guarantee the users' consistent experience of customized services during handoff procedure and improve network performance,this thesis studies a heterogeneous network selection and bandwidth allocation algorithm based on handoff efficiency.The algorithm includes two steps.First,a simple filter and multi-attribute decision are used to determine the candidate network set.Then the handoff efficiency is defined as the ratio of the system throughput to the number of handoffs.In the above candidate network set,considering users' Qo S requirements and system bandwidth as constraint,with the goal of maximizing handoff efficiency,jointly optimize network selection and bandwidth resource allocation.In order to reduce the complexity of the above optimization problem,we decompose the original optimization problem into two sub-problems: network selection and bandwidth allocation.It is solved by step-by-step optimization and loop iteration.The simulation results show that the heterogeneous network selection and bandwidth allocation algorithm studied in this thesis can effectively reduce the number of handoffs and improve system performance.