Research On Resource Scheduling Algorithm Of Aeronautical Ad Hoc Network Based On STDMA

Aeronautical mobile communication is the transmission and exchange of information in the flight. Now it mainly relies on satellite-based network and ground-based network. Due to the high cost, large delay and limited capacity of satellite-based network, and the limited coverage of ground-based, aeronautical ad hoc network consist of civil airplanes is hopefully to become an important make-up of aeronautical mobile communication. In the aeronautical ad hoc network, wireless resources are very limited. How to meet the quality of service of different business and carry on the scheduling for wireless resources reasonably and effectively become the key problems need to be solved. And the medium access control can effectively solve the problem that users how to share the limited wireless channel resource. The queue scheduling mechanism can guarantee the network quality of service. The medium access control and the queue scheduling mechanism are important content of resource scheduling. Based on the analysis and conclusion of all kinds of MAC protocols,the thesis employs spatial reuse time division multiple access protocol. In STDMA, the time slot scheduling algorithm is the core content. Therefore, the thesis mainly studies on the time slot scheduling algorithm of STDMA and queue scheduling algorithm based on STDMA. The main contributions and achievements are:(1)A time slot scheduling algorithm of STDMA based on graph coloring is proposed. The existing Schneider algorithm is totally distributed algorithm and it has good convergence rate. Howerver, the algorithm is node coloring and only considers the main interference. Besides, it only takes node ID into consideration when solving the maximum independent set and the required local information and overhead will increased if considering the secondary interference. Therfore, there are some limitations when the algorithm is applied to the aeronautical ad hoc network. In the thesis, the modified algorithm is proposed based on Schneider algorithm. Firstly, the aeronautical ad hoc network is abstracted as graph G(V, E), and then the graph is transferred into interference graph on the basis of protocol interference model. Next, the MIS is obtained based on the interference graph and the link in MIS is colored. Repeat the process until all links obtained a color. Finally, according to the result of coloring, all links in graph obtain a time slot. The proposed time slot scheduling algorithm improved spatial reuse degree using edge coloring. And the interference degree of link is the standard whether to join the MIS. The simulation results show that the proposed algorithm can achieve higher spatial reuse degree and the requried number of slots is less than the Schneider algorithm. Therefore, the proposed algorithm can achieve more network throughput. At the same time, directional antenna has a better performance than omnidirectional antenna.(2)A queue scheduling algorithm based on STDMA is proposed. The proposed algorithm can distinguish different priority bussiness of aeronautical ad hoc network and effectively solve the problem of head of line blocking in directional transmission mode combining with the modified time slot scheduling algorithm. The thesis analyzes the probability of head of line blocking in theory. And the simulation results show that the proposed algorithm can guarantee the requirements of delay for high priority business and its average packet queuing delay is also less than the first in first out scheduling algorithm and priority queue scheduling algorithm. The proposed algorithm can reduce waste of time slot and maximize the utilazation of time slot resource by avoiding head of line blocking. Furthermore, the proposed algorithm can increase the network throughput and reduce the average packet queuing delay.