关键词: 低TPS, 分片, 共识机制, 实用拜占庭容错算法（PBFT）, 多轮验证

Abstract:

Sharding technology is a feasible scheme to solve the problem of blockchain expansion, but there is a contradiction between the scale of the sharding and the verification validity in shards：with PBFT consensus algorithm, even if the proportion of Byzantine nodes is no more than one third in all nodes, there is a certain probability that the proportion of Byzantine nodes will exceed one third in a single sharding, resulting in the failure of verifying the consensus. Aiming at this problem, it proposes an improved scheme of multi-round PBFT consensus, which can not only improve the scale of the sharding, but also ensure the verification validity of the PBFT consensus in the sharding. Firstly, it summarizes the schemes of the known projects and analyzes their advantages and disadvantages. Then it analyzes consensus verification validity of sharding in detail. Lastly, it proposes and discusses the multi-round verification scheme, giving reasonable value of multiple rounds in the case of high Byzantine nodes proportion. Based on the comparison between the experimental data and the existing scheme, it verifies the validity of the multi-round scheme in improving the overall TPS, which provides a useful reference for the further study of the sharding scheme.

Key words: low Transaction Per Second（TPS）, sharding, consensus mechanism, Practical Byzantine Fault Tolerance（PBFT）, multi-round verification