Design And Simulation Of Access Algorithm In Air & Space Network

Air & Space Network is consisted of different kinds of terminals and stations which at different heights, using different space links. How to guarantee different users'access QoS (Quality of Service) is the problem that must be solved by access algorithm. However, the access algorithms used in ground and satellite communications can not satisfy the requirements of short access delay and high reliability in Air & Space Network. So it is very important to design new access algorithms which can provide its QoS.Firstly, we analyze the characteristic, application foreground, significance of Air & Space Network and introduce its tendency. Then we investigate its environment, including the category of terminals, services and priorities. By analyzing the requirements on link layer performance of access from the target high-speed terminal, the factors that affect its performance are systematically discussed. Following, we analyze the characteristic of access algorithms which are used in satellite communications. Aiming at the long propagation delay and high bit error rate in Air & Space Network, we propose a novel access algorithm m-RRC (multirequest - Random and Reserve Combine). Through analyzing the access probability, we deduce the equations of average access delay and calculate the optimal sending times of requests in the communication scenario of GEO (Geostationary Earth Orbit)-LEO (Low Earth Orbit).Finally, an OPNET model for Air & Space Network access algorithm is built, and the advantage of m-RRC algorithm is proved by three simulation experiments.