Research On Efficient Off-chain Transaction Methods Based On Payment Channel Network

While more and more people are using cryptocurrencies,the scalability of cryptocurrencies remains a serious challenge.Payment channel network,which provides off-chain settlement of transactions,is one of the most promising solutions to address the blockchain scalability issues.However,some basic problems in payment channel network need to be solved.One of the basic problems is the depletion of deposits in the payment channels.The simple routing schemes such as shortest path routing may exhaust the deposits in the key payment channels,greatly reducing the transaction success rate of the system.Another fundamental problem is the absence of borderline users in the payment channel network to perform transactions.When a user in the payment channel network cannot execute the transactions for a long time,the user will not receive any revenue(fees).Therefore,users often quit the payment channel,resulting in an increase in the number of transactions posted to the blockchain.In order to improve the efficience of payment channel network,this thesis first proposes the concept of payment junction,and proposes three mechanisms to improve the efficiency,stability and anti-attack ability of payment junction.A payment junction can be created by multiple users,and the user in the payment junction uses his entire deposit in the payment junction to transact directly with other users in the same payment junction.According to the feature of payment junction,this thesis discusses the number of on-chain transactions,user deposit,payment request amount,user cost and channel balance of payment channel network using payment junction.Through quantitative analysis,it is found that the payment junction has great advantages in the above points.The experimental results show that when using the payment junction,the transaction success rate of shortest path algorithm,shortest path-channel balancing algorithm and landmark routing algorithm can be increased by 4.07%,2.34% and 0.88% on average,respectively.In addition,the experimental results show that the payment junction has obvious advantages in path length,user deposit and user cost.Secondly,this thesis considers the case that the borderline users in the payment channel network and payment junction are easy to quit,increasing the transaction pressure to the blockchain.The borderline users appear in the network mainly because the users cannot complete the transaction due to insufficient deposit,or the transaction path is too long to be selected as a path.This thesis proposes a reputation system to describe the status of each payment channel.In order to reduce the impact of borderlineusers on network performance,based on reputation system,the OTR-RS(Off-chain Transaction Routing Algorithm based on Reputation System)is proposed to comprehensively consider the reputation and path length of payment channel,so that the borderline users in the payment channel network with a high reputation will have the chance of being selected by routing.The simulation results show that,compared with shortest path algorithm,shortest path-channel balancing algorithm and landmark routing algorithm,the transaction success rate of OTR-RS can be increased by 54.54%,53.99% and 19.20% on average,respectively.In addition,the experimental results also show that OTR-RS has obvious advantages in the path length,user participation and channel balance degree.