Contention Window Selection of IEEE 802.11 for Wireless Blockchain Network

Blockchain technology exhibits significant potential in 6G communication systems to establish a reliable decentralized environment between untrusted parties. Currently, most studies on blockchain systems are based on wired environments while limited attention is paid to wireless blockchain network (WBN). Due to the scarcity of spectrum resources as well as the frequent peer-to-peer interactions of typical consensus algorithms for blockchain, the use of traditional communication protocols in WBN is prone to result in conflict storms. Therefore, existing wireless communication protocols are not always suitable for WBN. In this work, we aim to investigate the influence of the commonly employed IEEE 802.11 protocol on the performance of WBN and propose modifications to enhance its compatibility with WBN. The performance is theoretically evaluated through throughput and block confirmation delay and it is found that the number of nodes as well as the contention window (CW) size have a significant impact on the network's performance. On this basis, the optimal CW selection mechanism for different network scales is proposed to improve the performance and efficiency of the WBN. Finally, the simulation results show that choosing an appropriate CW size ensures both a high throughput for the network and a low confirmation delay for each block.