Connectivity-Aware Contract for Incentivizing IoT Devices in Complex Wireless Blockchain Networks

Blockchain is considered to be the critical backbone technology for secure and trusted Internet of Things (IoT) on the future 6G network.However, the IoT network is usually with the complex wireless environment, where the communication is not reliable and the connectivity is complicated. Deploying a blockchain system in the complex wireless IoT network is challenging. Due to the limited resources, complex wireless environment and the property of self-interest, IoT devices do not have the internal motivation to consume energy and time to maintain the blockchain. Furthermore, existing incentive mechanism in blockchain is not compatible well with the wireless IoT network. In this paper, to incentivize IoT devices to join the construction of the wireless blockchain network, we propose a multi dimentional contract which optimizes the blockchain utility while addressing the issues of adverse selection and moral hazard. Specifically, the proposed contract not only considers the IoT devices' hash rate and transmission power, but also explores the network connectivity from the perspective of the network complexity. We incestigate the impact of these factors on energy consumption and the block confirmation probability by the experiments under different network sizes and average link probability. Numerical results demonstrate that our proposed contract mechanism is feasible and effective. Compared with the contract with adverse selection, the proposed contract improves blockchain utility by 35%, which is closer to the perfect information contract.