Research On Key Technologies And Simulation Of UAVs Ad Hoc Networks

The deployment of the UAVs Ad Hoc networks does not need any establishedsupporting infrastructure, the network architecture isn’t limited to the star-structure withcontrol base station as the center. Moreover, the multi-hop message delivery mode breaksthe constraint on which the UAV can only work within the communication range of centralbase station. Consequently, the UAVs Ad Hoc networks, whose coverage is enlarged, hasthe potential to revolutionize the battle field communication. Currently the study of UAVsAd Hoc networks is encumbered by the difficulties such as tedious and poor controllability,bad adaptability etc. Based on the joint analysis and design of communication and controlsystems, this dissertation studies some technologies of the UAVs Ad Hoc networksincluding the fault-tolerant topology control, the routing protocol of delay-tolerant network,and the simulation-based analysis and optimization. The main contents of this dissertationcan be summarized as follows:(1) Firstly, the state of the art of the UAVs Ad Hoc networks is surveyed and theadvantages and disadvantages of different methods are compared. In order to get the besttrade-off between the effectiveness of the movement control and the network performance,the joint analysis and design strategy is proposed which combines the communicationnetwork performance with the controlling mobility.(2) Vertex-biconnectivity is basic feature of fault-tolerant networks. When the nodesin the network are controllable, the mobility-based control method is investigated to realizefault-tolerant networks. For the chain-formation network, a simple and effective movementalgorithm which requires only the local information of the neighbor nodes is proposed toreduce the spending of communication and the consume of resource. For the flat-formationnetwork, the fault-tolerant problem is converted to the mobility-based min-total-distancevertex-biconnectivity augmentation problem for graph, a two-phase centralized movementcontrol algorithm is proposed. In the first phase, the nodes are immovable, thevertex-biconnectivity of a given communication topology graph is achieved by addingedges which join the different vertexes. The search of the min-cost set of edges is aNP-hard problem. In the memetic algorithm frame, the problem specific globalevolutionary strategy, the local improvement procedure and the cost define ofaugmentation edge considering node movement constraint are developed to find thecheapest possible set of additional edges which makes the graph vertex-biconnected. In thesecond phase, with the augmentation edges as heuristic, the vertexes which the edgesconnected move towards each other to establish edges. The related nodes also move as thefollowers with the leader-follower movement control algorithm based on the consensusalgorithm. After nodes moved, the changed network becomes vertex-biconnected so thefault tolerant configuration is achieved. (3) When only part of the nodes in the network is controllable, the relay nodeplacement method is investigated to realize fault-tolerant networks. For the flat-formationnetwork, the minimum relay nodes placement problem is converted to the minimumbottleneck Steiner tree problem. Following the Steinerized research pattern, an algorithmframe based on the min-cost spanning subgraph of a complete graph is proposed. Tworelay node placement algorithms are investigated, the first one is a polynomial timeapproximation algorithm, and the second one is a random algorithm which can improve theresult on average. When the node placement locations are not limited to the straight linebetween the vertexes, an improvement method can be used to search the relay nodes setswhich can be replaced with much less nodes in the final resolution, so the number of relaynode is reduced and the performance of algorithm is improved.(4) When the network experiences frequent and long duration partition, and the nodesare uncontrollable, the information transmission based on the delay tolerant networks’“store-carry-forward” routing pattern is investigated. Combining with the parallel action ofthe redundancy-based routing and the selectivity of the utility-based routing, a hybridrouting is proposed in which the requirement of network knowledge and the duplication ofmessage are small. The optimal stop theory is used to decide whether to copy the messageto the neighbors in contacted, so the balance between the delivery speed of the messageduplication and the average utility of the message duplication carrier is achieved. Thehybrid routing combined the message duplication delivery strategy and the duplicationnumber control strategy, so the usage of network is small, and the extendibility is improved,and the best tradeoff among several performances of network is achieved, such as thedelivery delay, the delivery success rate, and the usage of network.(5) To deal with the difficulties in analysis, validation and test of the algorithms andprotocols, the mathematical analysis and the experimental test are investigated, the digitalsimulation is used to analysis and test the performance of network. The UAVs Ad Hocnetworks simulation system is developed based on distributed interactive simulation. Thesimulation system is based on the High Level Architecture, so the reusability of thesoftware resources and the interoperability of the simulation module are realized. Toaddress the dilemma between the accuracy of simulation-model and runtime efficiencywhich take place in the simulation-based optimization of the analysis and designprocedures of complex system, the metamodel-based optimization is investigated. Aninstance in optimization of the network performance is implemented to evaluate thesimulation system and the algorithm in the dissertation.