Research On Handover Control Algorithms Of High Speed Terminals In Air & Space Network

Handover technology is one of key technologies of the mobile communication networks, which can recover and maintain communication and balance traffic load in bad wireless channels and moving conditions. Therefore, the handover technology directly affects the quality of service and performance of wireless communication systems. As the most critical part of handover algorithm, handover decision impacts the success and performance of handover algorithm, moreover, it is an important precondition to achieve seamless handover in wireless communication systems. In Air & Space Network, characteristics of wireless channels are different from characteristics of wireless channels in existing terrestrial wireless communication systems. In Air & Space Network, terminals usually have high speed even up to several or several ten times of the speed of sound. Therefore, it is only a very short time left for handover decision and execution in Air & Space Network. These features conduce some great technical challenges for handover control algorithms of high speed terminals in Air & Space Network.Firstly, based on STK platform, five typical handover scenarios are selected to analyze the visibility, overlapping coverage and the received signal strength for a high speed terminal in Air & Space Network. Secondly, considering the high speed characteristics of the terminals, a trajectory prediction algorithm with low computational complexity is proposed for handover decisions. Simulation results show that the prediction accuracy of the new algorithm meets requirements of the handover decision. Furthermore, considering the trajectory prediction information of the high speed terminals and the quality of service, as so as the quality of signal, a novel multi-attribute handover decision algorithm is developed based on gray relational coefficient and the trajectory prediction information.Finally, a high speed terminal trajectory generation algorithm is designed to simulate movements of the high speed terminals to configure corresponding handover scenarios in Air & Space Network. Five simulation scenarios are established in the OPNET platform. Compared with the algorithm only based on gray correlation coefficient, Simulation results show that the proposed multi-attribute handover decision algorithm can not only choose the best target access point but also trigger the right handover time and reduce unnecessary handover times. Moreover, the proposed algorithm can be compatible with the handover decisions of homogeneous and heterogeneous networks.