Research On QoS Routing Technology Of Aeronautical Ad Hoc Networks

As a new research and applications of mobile ad hoc networks, aeronautical ad hoc network has got extensive concerns in industry and academia. Among the key technologies, mobile routing largely determines the performance of the aeronautical ad hoc networks. Since low-altitude airspace has been opened in many countries around the world, the traditional mobile ad hoc network routing technology is difficult to meet the requirements of growing aeronautical communication service.On the one hand, aeronautical ad hoc network is self-organizied without central control nodes and every node is equal, which is like mobile ad hoc network. On the other hand, aeronautical ad hoc network has special features, such as large-scale, high dynamic, time-varying channel, limited bandwidth, connectivity restrictions, serious communications environment and other unique characteristics. All of above have attracted the enthusiastic attention from industry and academia. Therefore, it is always a hot and difficult research issues for aeronautical ad hoc networks to provide a stable, efficient and reliable routing algorithm in favor of user’s communication experience.Hence, this paper mainly focuses on a series of key technical technologies of QoS routing for aeronautical ad hoc networks in the low-altitude airspace. Through in-depth study, our research has several significant contributions.1) With the growth of aeronautical multimedia traffic and communication, bandwidth limited air link is difficult to guarantee real-time services. Hence, a delay-aware stable routing algorithm is introduced based on research of the aeronautical radio channel allocation mechanism. The proposed algorithm combines relative velocity and expected queueing delay of nodes as a united measurement in route discovery, which could effectively reduce local congestion, improve network throughput, decrease the end to end delay, and meet the demands of real-time aeronautical communication services. 2) In low-altitude airspace, aeronautical communication system features quick changes of network topology and frequent updating of node position. In addition, the slight variation of neighbor nodes on the boundary of radio communication scope is easily to cause interruption and retransmission. These cases will consume much network overhead and put great pressures on limited network resources. Hence, an ADS-B system aided geographic routing scheme is proposed. In this scheme, we establish routing table for next hop selection by using the position and velocity of aircraft provided by airborne ADS-B system so that the network overhead could be reduced effectively. Furthermore, the algorithm takes aircraft velocity into account in routing discovery and selects the node which can reach target in shorest time as the next hop so that the packet delivery ratio can be significantly improved.3) In the large-scale aeronautical ad hoc networks, a single active or passive routing technique has less efficiency. Based on the research of group mobility characteristic of aircraft node in low-altitude airspace, a mobility aware clustering algorithm is presented firstly. The clustering algorithm integrates mobility status and degree of aircraft node to form stable and big clusters. Then, a cluster based hybrid routing scheme is adopted, with active routing inside the cluster while passive routing among the cluster. As a result, it could effectively reduce the overhead, decrease the communication control overhead and improve network resource utilization.4) In low-altitude airspace, aeronautical ad hoc network operates in a wireless environment with high error rate, high fading and serious interference. Thus, wireless links between aircraft node are prone to interrupt, and frequent retransmission often lead to disordered packets. To solve the problems above, a cluster based multi-path routing algorithm with network coding is presented. By using the additional linear encoder in the source and intermediate node, the destination could recover the original message from incompleted message or disordered packets. The algorithm could effectively reduces the number of redundant data packets and network transmissions, improve the fault tolerance and reliability of multi-path routing.