An Evaluation of Sharding Protocol with Uneven Nodes Settings

The fusion of IoT and Blockchain (i.e., IoT-Blockchain) promisingly revolutionizes numerous domains. However, IoT-Blockchain systems may face scalability challenges due to a large number of IoT devices and blockchain performance. Sharding, which divides the blockchain into smaller groups, offers a solution to enhance blockchain scalability. However, most previous sharding research typically considers even node distribution in a shard (i.e., a fixed node number). Hence, it may not capture the characteristics of IoT- Blockchain systems well, where nodes are diversely distributed. This paper investigates a new scenario of shards having unevenly distributed nodes, aiming to see the impacts of the scenario on sharding protocols. More specifically, we evaluate the BrokerChain protocol on the sharding-based emulation platform (i.e., BlockEmulator) in scenarios with even and uneven node distributions. The results show that the protocol performance degrades with the uneven node distribution, suggesting the need for a dynamic sharding protocol.