Research On Traffic Offloading Strategy In Hybrid Satellite Terristrial Networks

The hybrid satellite terrestrial network(HSTN)has become the focus of current research to deal with the problem of fast-growing traffic because of the characteristics of wide coverage,low transmission cost and large-scale service access.It is an effective way to alleviate the net congestion at low cost to offload the traffic from the overload area to satellites with abundant resources.However,the time-varying characteristics of topology,the dynamic characteristics of traffic demand and the satellite energy constraint of satellites will affect the performance of traffic offloading.The interest relationship between network operators increases the complexity of traffic offloading.Therefore,this thesis analyzes the traffic offloading strategies in HSTN,including the following two aspects:1.In view of the problem that traffic offloading in HSTN involves the interests of different network operators,the traffic offloading scheme based on the economic profits of mobile network operator(MNO)by considering the dynamic and interference characteristics of HSTN is studied.Firstly,a HSTN model with low earth orbit satellites and base stations and cloud core network is constructed and the problem of co-channel interference is analyzed.Then,an auction model is adopted to analyze the economic profits of traffic offloading in HSTN,and the optimization problem of maximizing the profits of MNO is formulated.Following that,a reverse auction with cell grouping(RA-CG)scheme is proposed for traffic offloading.In RA-CG,a Hungarian-based reverse auction(HRA)algorithm is designed to find the optimal cell-satellite association solution in terms of the economic profits within each interference-free group,which is obtained by a cell grouping algorithm.Simulation results show that the proposed RA-CG can not only maximize the profits of MNO and improve the network offloading rate,but also achieve higher spectrum efficiency.2.Aiming at the impact of satellite energy consumption on satellite offloading cost in HSTN,a traffic offloading scheme based on satellite network cost efficiency is studied.Firstly,the energy collection and consumption of the satellite are analyzed,and the satellite offloading cost model is constructed based on the satellite energy and battery lifetime.Then,considering the traffic offloading demand of cellular base stations,the cost-effectiveness optimization model of satellite network is established.Based on this,a joint power-spectrum allocation scheme is proposed to find the optimal cost-efficiency offloading solution for satellite network.The simulation results show that the scheme can maximize the amount of offloading traffic with the minimum satellite network cost.