Against Colluding Mining with Reward Sharing in MEC Empowered Mobile Blockchain System

Mobile edge computing is considered as a promising solution to mobile blockchain system, where mobile nodes with limited computing capability may participate the mining process by offloading the computing intensive mining tasks to nearby edge service providers (ESPs). To mitigate the collusion between ESP and miners, we propose a reward sharing model in this paper, where each miner will share part of the mining rewards to ESP to build a mutual cooperation group. We model the interaction among the ESP and miner nodes as a two-stage Stackelberg game. Then, we obtain the optimal edge computing demand and the corresponding price of each miner by solving the Nash equilibrium of the game iteratively with gradient descent method. We also compare the revenues under both collusion and normal mode with the proposed reward sharing scheme. Simulation results show that the more mining rewards that miners share to ESP, the higher the computing resource demands of miners and the less of the unit price of the computing resources. In addition, if the block size of the colluding miner is much larger than other miners, the ESP can obtain higher revenues rather than colluding.