On the Performance of Wireless PBFT-Based Blockchain Network with IEEE 802.11

The ever-increasing mobile users pose a great challenge to the current centralized structure, where the failure of the network center significantly compromises privacy and data security. Practical byzantine fault tolerant (PBFT), a voting-based consensus blockchain, is a plausible solution to the wireless network for its distributed and decentralized traits, and it is not computation-intensive. The view change mechanism guarantees the liveness and resilience of PBFT, but it also causes delay. Moreover, spectrum is usually shared in the wireless network, introducing additional channel contention. Hence, we develop a framework investigating the impacts of channel contention on the wireless PBFT network using the IEEE 802.11 protocol. Based on the Markov model, we derive the throughput, transmission success probability, and transaction confirmation delay of such a network. Furthermore, we derive the view change delay in reference to the transaction confirmation delay. The analysis and results show that channel contention impacts in two ways. It impairs the success probability and increases the chance of view change. Optimal pairs of packet arrival rate and contention window size are formulated to maximize the consensus's success probability without sacrificing the overall network performance. Further, the optimal pairs under different network sizes are demonstrated for straightforward guidance.