Efficient Data Trading and Placement in Blockchain-based Edge Computing Systems

Edge devices (e.g., smartphones, tablelet PC, IoT devices) are becoming more prevalent in people’s daily lives. With advanced sensors and processors, these devices can create massive data. These data can be used for predictive maintenance, enhancing user experience, increasing productivity, etc. These valuable data allow data producers to sell to consumers directly to generate income. Blockchain and smart-contract technology can be used to ensure transactions to be unmodifiable and undeniable. This paper first proposes a blockchain-based data relay and transaction model for the data producer, relay and consumer in edge computing. We then present a new consensus mechanism Proof-of-Data-Trading (PoDT) by combining Proof-of-Work (PoW) mechanism with Proof-of-Stake (PoS) consensus mechanism, which enables the proposed blockchain system to reach consensus with low energy consumption for edge devices. Moreover, we develop an approximation algorithm to store encrypted copies of data items on relays with smaller costs. Extensive simulations show that our proposed blockchain system works efficiently in edge computing. It achieves up to 8.19% higher profit for the data producer with the help of relays and consumers using 84.6% less time to get the data item. In addition, the new consensus mechanism consumes 87% less time when compared with the traditional PoW consensus mechanism.