Research On Key Technology Of Sharding For Intelligent Transportation Blockchain Application

In the 14 th Five-Year Plan,intelligent transportation has become a key area for future development.With the development of new technologies,Intelligent Transportation System(ITS)will bring more convenience to people’s life and will strongly promote social and economic development.However,there are common problems in ITS such as difficult data sharing,data security,and distrust between entities.Many research works have combined blockchain with ITS applications,using decentralization and other characteristics of blockchain to provide data security and a de-trusted environment for ITS applications.However,the traditional blockchain is inefficient and cannot cope well with the challenges of large amount of data,concurrent data processing,and high realtime in ITS.Therefore,this dissertation focuses on blockchain scaling techniques in intelligent transportation blockchain applications to improve blockchain execution efficiency and reduce storage overhead,making blockchain more applicable to ITS applications.The main work is divided into three aspects as follows.(1)To address the problems of low blockchain efficiency and high storage overhead in intelligent transportation blockchain applications,a sharding model for blockchain applications of ITS is proposed to improve the blockchain efficiency and reduce data storage.The concept of backup shard is proposed in the sharding model to improve data availability and shard security by setting backup shards and retaining partial data redundancy.In addition,the blockchain storage process is combined with encoding scheme to encode data,and store the encoded data in different nodes to further reduce the average storage overhead of data.(2)Aiming at the problem of complex cross shard transaction processing and difficulty in achieving consistency in the sharding,an effective cross shard transaction processing method is proposed to simplify the cross shard transaction processing process based on the principle of reducing the proportion of cross shard transactions.Through the backup shard set in the sharding model,the cross shard transactions are converted to intrashard transactions to reduce the proportion of cross shard transactions.On the one hand,with the help of backup relationship,the backup node handles cross shard transactions;On the other hand,the method of node migration is proposed,and shards builds temporary relationships to handle cross shard transactions.(3)Considering the numerous applications in ITS,the sharding model is extended to composite scenarios,a heterogeneous model of shard for composite application scenarios is proposed,and a method for transaction processing under the heterogeneous model is given.Under the heterogeneous sharding,consensus algorithms used by shards to reach consensus and the structure of the stored data are allowed to be different.This dissertation gives a method to determine the consensus algorithm and data structure for shards.At the same time,the concept of relay shard is proposed,and set up relay shard to handle transactions across heterogeneous shards.The transaction processing will also involve the transformation process of different data structures on different shards.Taking the intelligent transportation blockchain application as the research object,and taking improving the efficiency of blockchain and reducing storage overhead as the basic principle,this dissertation proposes a sharding model,studies the cross shard transaction processing method,and extends the research to composite scenarios.The experimental results illustrate that the work of this dissertation outperforms other schemes in terms of improving throughput and reducing storage overhead,and is more applicable to ITS scenarios.