Cooperative Caching Services on High-Speed Train by Reverse Auction

With the explosion of data traffic, the use of caching technology to offload data traffic is a very effective way to alleviate network pressure, especially in high-speed train (HST) scenarios. And when users participate in the caching game, the costs of data offloading are greatly reduced. However, current research on users' participation in data traffic offloading is not much; and there are user security and data reliability issues in the cache of device-to-device (D2D) network. Therefore, in this paper, we propose a novel scheme that user terminals (UTs) cooperatively cache wireless services to the intelligent routing relay (IRR) side in HST scenarios; and we establish a reverse auction model to motivate UTs to collaborate and cache. In this model, IRR acts as the purchaser of the wireless services and UTs are suppliers and consumers. We propose a synchronous reverse auction strategy (S-RAS) to maximize the social incomes at first. However, UTs often have to wait for a long time before the auction begins. Then, we adopt an asynchronous reverse auction strategy (A-RAS) to minimize UTs' waiting time. Ultimately, in order to minimize UTs' waiting time while maximizing social incomes, we propose the popularity based hybrid reverse auction strategy (PB-H-RAS) considering both the advantages of S-RAS and A-RAS. Simulation and experiment results verify the effectiveness of the proposed PB-H-RAS strategy; and they also show that the performances of PB-H-RAS strategy are better than the other two strategies in terms of final incomes and completion rate.