Block Interval Adjustment Toward Fair Proof-of-Work Blockchains

We propose a finer measure of fairness than that found in the literature. We then propose a method of adjusting the block interval that maintains fairness and high transaction throughput. The existing fairness measure is so rough that its judgement is considered fair as long as a node can start mining by the time another node mines a block. However, the time left for mining differs between nodes; this can result in unfairness. Therefore, we define the proposed fairness as the mining success rate of miners depends only on computational power. This is a finer measure of fairness than existing one. We propose a method for adjusting the block interval to maintain a certain level of fairness. Most Proof of Work (PoW) blockchains fix the block intervals and do not consider fairness. In contrast, our proposed technique adjusts the block interval based on the fork incidence rate. Our method maintains fairness even if the network conditions change. Simulations confirm that our technique maintains fairness even when the Internet performance varies.