wChain: A Fast Fault-Tolerant Blockchain Protocol for Multihop Wireless Networks

This paper presentswChain, a blockchain protocol specifically designed for multihop wireless networks that deeply integrates wireless communication properties and blockchain technologies under the realistic SINR model. We adopt a hierarchical spanner as the communication backbone to address medium contention and achieve fast data aggregation withinO(log Nlog Γ)slots whereNis the network size andΓrefers to the ratio of the maximum distance to the minimum distance between any two nodes. Besides,wChainemploys data aggregation and reaggregation as well as node recovery mechanisms to ensure efficiency, fault tolerance, persistence, and liveness. The worst-case runtime ofwChainis upper bounded byO(flog Nlog Γ), wheref= N/2is the upper bound of the number of faulty nodes. To validate our design, we conduct both theoretical analysis and simulation studies. The results not only demonstrate the nice properties ofwChain, but also point to a large new space for the exploration of blockchain protocols in wireless networks.