Design Of Lightweight Blockchain Scheme And Research And Implementation Of Credible Collaborative Computing Mechanism For UAV Ad Hoc Network

Small unmanned aerial vehicles(UAVs)are widely applied in many fields.However,single UAV can no longer meet the needs of many scenarios due to its limited ability,and multiUAV cooperation has gradually become the hot research issue in the field of UAV applications.UAVs can form ad hoc network and cooperate with each other to greatly improve efficiency of the swarm.Compared with traditional ad hoc networks,UAV ad hoc network is featured with fast movement,frequent replacement and lack of support from ground infrastructure.Also UAVs usually carry security-related and privacy-sensitive information during work,e.g.industrial data or military intelligence,and therefore they are facing more complex security issues.Blockchain is a solution to effectively dealing with most security issues in distributed systems,and has been widely used in Internet of Things(Io Ts)in recent years.As a typical Io T scenario,the security level of UAV ad hoc network can be greatly improved by combining blockchain technology with its systems and applications.However,there are still two challenges.Firstly,in the view of system architecture,existing blockchain scheme cannot be directly applied to low-computing,high-dynamic and large-scale UAV ad hoc network.More lightweight blockchain should be designed for multi-UAV.Secondly,in the view of practical applications,many security issues existing in current multi-UAV cooperative computing mode should be handled,such as malicious or selfish nodes.Consequently,this thesis studies the lightweight blockchain scheme and the computing resource trading mechanism for UAV ad hoc network.Specifically,blockchain is used to guarantee security of UAV ad hoc network and the credible collaborative computing mechanism is designed base on smart contracts.The main contributions of this thesis are as follows.Firstly,aiming at the problem that traditional blockchain cannot be applied to UAV ad hoc network,this thesis proposes a more lightweight blockchain design.Considering the clustering feature of UAVs,an intra-cluster consensus method based on trust evaluation,as well as an inter-cluster two-layer consensus based on cluster sharding,is proposed to reduce consensus consumption,save cross-cluster overhead and improve scalability of the swarm.Simulation experiments show that,compared with PBFT and random sharding scheme,the proposed method can reduce intra-cluster consensus delay by 47%,inter-cluster consensus delay by 31%,and cross-cluster message overhead by 93% on average for different scales of UAV swarm.Secondly,aiming at securing multi-UAV collaborative computing,this thesis proposes the computing resource trading mechanism based on smart contracts.UAV nodes can traceably promote computing resource trading and collaborative computing according to pre-built smart contracts.The computing resource pricing and allocation problem in UAV ad hoc network is studied to optimize benefits of each node.Simulation experiments show that the above methods can achieve reasonable computing resource pricing and allocation,and can reduce the total task time by about 57% compared with local computing.It can ensure the security of multi-UAV collaboration while improving the utilization of swarm resources and the efficiency of computing tasks.Thirdly,based on the above research,the collaborative computing prototype system based on blockchain for UAV ad hoc network is designed and developed.The system includes the networking part of UAV ad hoc network and blockchain network,and the implementation part of smart contracts and collaborative computing.By practical experiments,the complete process of multi-UAV computing resource trading and collaborative computing based on blockchain is conducted,which strongly verifies the theoretical work of this thesis.To sum up,this thesis makes an in-depth exploration of utilizing blockchain to enhance the security of systems and applications for UAV ad hoc network.The results of a series of simulation and practical experiments show that the schemes proposed in this thesis can effectively secure multi-UAV systems and applications.This work has positive value for exploring the practical application of blockchain in multi-UAV scenarios.