Research On Heterogeneous Relay Networks In Emergency Communications

Due to the large population and vast territory of China,sudden social events and natural disasters sometimes occur.As a special type of communication,emergency communication is urgent need for depth study.On the one hand,a single cellular network can not meet emergency communications so that heterogeneous networks(HetNet),used to improve network access and flexibility,become an effective emergency communication network structure.On the other hand,direct transmission is restricted by communication conditions in emergency communications.Relay cooperation,used to expand the transmission range and improve the reliability of the link,becomes a reliable technology for emergency communications.The combination of heterogeneous networks and relay cooperation is called heterogeneous relay networks.The application in emergency communications is the focus of this paper.Aiming at different emergency communication scenarios,reasonable network framework and efficient network resource allocation become the key issues in heterogeneous relay networks.This paper investigates two common emergency communication scenarios: emergency communication with hot spots caused by sudden social events and emergency communication islands caused by natural disasters.Emergency communication with hot spots are caused by sudden social events.There is the congestion problem in communication hot spots.In order to alleviate congestion,we propose a three-layer heterogeneous relay network model composed of base stations,relay networks and users in hot spot cell.Aiming at the model,the problem of quality of experience(QoE)optimization is proposed by connectivity and average delay of users.By solving this optimization problem,an efficient resource allocation with low complexity is proposed.With simulation results,it can be seen that the proposed method is effective to solve the congestion problem and obtain a good quality of experience.Emergency communication islands are caused by natural disasters.Basic communication facilities are destroyed and affected users need to send signals for rescue.In order to make rescued users as many as possible,we propose a three-layer heterogeneous relay network composed of satellites,relay networks and affected users.Combined with the model,the surviving probability(SP)optimization problem is proposed by the current user surviving rate and future user surviving probability.We propose a resource allocation to match satellites,relays and users.With simulation results,it can be seen that the proposed method can provide the biggest chance of survival for affected users.