Research On WiFi Offloading Strategy For 5G-WiFi Integrated Networks

With the rapid development of mobile Internet and the extensive utilization of intelligent terminals,the mobile Internet data traffic increases dramatically.How to effectively mitigate the pressure of mobile data traffic,becomes one of the key issues for global operators.WiFi is a key approach to offload the mobile data from cellular networks.The heterogeneous integration between WiFi and cellular networks can realize multiservice and high-speed wireless access,improve the network system capacity as well as ensure the quality of communication services.In the next generation of mobile communication system evolved,integrating WiFi into 5G network becomes more urgent.As a promising data offloading solution,the effective WiFi offloading is the hotspot aspect of the 5G technology research.This thesis stems from the 863 project(national high technology research and development program of China)“Research on the General Technology of 5G Mobile Communication System” and its sub-project “Key technologies of WiFi integration network”(project number:2014AA01A706).According to the integration demands between WiFi and 5G and WiFi offloading schemes,the main research work includes the following three aspects:1.This thesis illustrates the concept of 5G and its key technologies,expounds the integration methods of WiFi and cellular network,provides the coexistence needs of WiFi and LTE-U(LTE in Unlicensed Spectrums)in 5G,and summarizes the common WiFi offloading mechanisms.2.For the scenario of heterogeneous network between cellular and Wi-Fi,a probabilistic offloading scheme based on the optimized objective function is proposed,which can improve the network performance.The state space of the network is modeled as a dimensional continuous Markov chain model.Using the successive over relaxation(SOR)algorithm obtains the steady-state probability of the state spaces,then combines with objective functions to optimize the network performance,solves the probability of the user to access WiFi.The simulation results show that the proposed offloading scheme can improve the network performance such as system throughput?network EE and reduce the call blocking probability,which compared with the typical schemes.3.For the coexistence scenario between WiFi and LTE-U in Unlicensed Spectrums,a WiFi offloading scheme based on cooperative game is proposed.In this scheme,combining WiFi AP data offloading with the ABS time-domain resource in LTE-U Macro eNode B,then based on the cooperative game model analysis,reaches a collaborative transaction between LTE-U BS and WiFi APs,gets the corresponding utility gain.Simultaneously,using the Shapley value distribution concept achieves WiFi APs fairly offloading.Through the analysis of the simulation results,it's proved that this scheme can improve the system throughput of the coexistence networks.This thesis deeply studies the WiFi offloading mechanisms and works out some meaningful research results,which will provide some reference for deep integration between 5G and WiFi.