Mac Protocol Research And Design For Highly-dynamic Aeronautical Ad Hoc Networks

With the development of research and application of mobile ad hoc networks and wireless sensor networks, a lot of domestic and international researchers have considered the application in aeronautical communication. A new concept of aeronautical Ad hoc network is put forward. As a special type of mobile ad hoc networks, the aeronautical Ad hoc network can be used to enhance situation awareness flight coordination and civil and military aviation efficiency. Compared to the ground network, there are many unique properties for aviation Ad hoc network, such as high speed of airborne nodes, frequently changing network topology, strict security requirements and poor communication environment. By these factors, many traditional network access protocols are no longer suitable for aeronautical ad hoc networks. Based on analysis of the existing MAC protocols, a novel MAC protocol is proposed in this thesis, which can be applied to aeronautical communication environment. The protocol can innovatively make the multi-nodes access the network within a relatively short time, allocate the time slots by the combination of fixed and dynamic slot allocation, support different priority services and unicast or broadcast communication mode, and provide routing and handoff scheme for the high dynamic topology.Firstly, we briefly introduce the development background and research status of aeronautical Ad hoc networks, and then describe characteristics of high dynamic Ad hoc networks. By analyzing and summarizing the application requirements of MAC protocol in aeronautical Ad hoc network, it is divided into four categories based on the different channel access mode: competition, scheduling, hybrid, and cross-layered MAC protocol design. The research progress of four kinds of protocols are described briefly, and then we summarize the characteristics, performance, and advantages and disadvantages of several typical protocols. According to the protocol design requirement of aeronautical Ad hoc network, we propose a new MAC protocol which adopts TDMA scheme. The structure of the network is a distributed three-level tree. Each node in the network is the backup center node, which can effectively ensure the network survivability. We design an effective mechanism for nodes to enter or leave the network. It not only can make the node access network quickly but also make different subnets realize fusion easily. The protocol supports multiple types of services. Based on the traffic set the center node uses the combination of fixed and dynamic scheme to allocate time slots, which can meet different traffic needs. Each node can transmit data via a directional switching antenna in occupied time slot, but monitor the network state and receive data using an isotropic antenna in other time slots. Without the RTS/CTS mechanism we employ a beacon frame to response an access request so that network overhead and delay can effectively be reduced. Finally, a protocol simulation model is established by using OPNET and STK software. We have designed a variety of simulation scenarios and simulated network performance under different loads. The simulation results show that compared with the protocol using RTS/CTS competition mechanism our protocol has lower network delay, higher throughput, lower packet loss rate and end-to-end delay. It will be more suitable for high dynamic aeronautical Ad hoc network system.