Performance And Double-spending Attack Analysis Of CSMA/CA Protocol On Blockchain In Wireless Communication

Blockchain is seen as a secure,reliable and promising technology to provide distributed ledger services.The impact of communication transmission delay on the original blockchain has not been well studied and ignored since it is primarily designed in stable wired communication environment with high transmission rate.However,such as Io T and MEC,blockchain applications gradually appear in wireless communication scenarios with the research and development of blockchain technology.In the wireless area network,any blockchain node may have to compete for wireless channel to broadcast transactions following media access control(MAC)mechanism.However,due to the scarcity of spectrum resource,the communication transmission delay may be significant and pose a bottleneck on the blockchain system performance and security.Current blockchain platforms cannot meet enough throughout in practical use.To develop blockchain applications in wireless Internet of Things(Io Ts),this thesis aims to investigate whether the widely used MAC mechanism is suitable for wireless blockchain networks or not,where MAC mechanism is carrier sense multiple access/collision avoidance(CSMA/CA).Considering the influence of access control in CSMA/CA on the block confirmation process,the thesis proposes a stochastic model to analyze the performance and security of wireless blockchain based on Directed Acyclic Graph(DAG).The main contents and conclusions of this work are listed as follows:First,specific to the performance of CSMA/CA based wireless blockchain,we establish transaction queuing model and analyze consensus process under two kinds of network traffic load.Then,according to the previous consensus process,we analyze the consensus delay of transaction in different loads.In order to quantify the wireless blockchain performance,this thesis solves the mathematical expressions of the two performance indicators in terms of transaction throughput per second and transaction loss probability.Compared with the prefect blockchain,simulation results show that the queuing delay under high load directly determines the performance of the blockchain.Meanwhile,the wireless blockchain performance is also limited by the capacity of wireless channel.Secondly,aiming to the security of CSMA/CA based wireless blockchain,the model of parasitic chain attack based on CSMA/CA is proposed to analyze the double-spending attack in the thesis.Through Markov model and calculus theory,we solve the probability of successful double-spending.For reflecting the impact of communication protocol,mathematic expressions of the successful double-spending in perfect communication and CSMA/CA are deduced respectively.Simulation results show that,either the attacker or honest nodes in wireless blockchain,they are constrained by CSMA/CA.