DOJS: A Distributed Online Joint Scheme to Optimize Cost in Mobile Edge Networks

Edge computing deploys computing and storage resources at the network edge, thereby providing services closer to terminal users. However, in edge networks, the mobility of terminals, the diversity of requests, and the dynamic nature of wireless channels pose significant challenges for efficiently allocating limited wireless and caching resources among multiple terminal devices. To address the issues of unbalanced network load and high caching costs caused by resource allocation in edge networks, we propose a Distributed Online Joint Optimization Scheme (DOJS). Specifically, we design a joint optimization scheme, referred to as DOJS, which combines centralized user association at the cloud with distributed cache placement at the base stations. This scheme analyzes the impact of terminal device association policies on caching costs and develops a caching cost model that integrates the activity level and content request probability of terminal devices. Based on this model, the relationship between user association selection and caching costs is analyzed, and a Game Theory-based User Association (GTUA) selection algorithm is proposed. In order to adapt to the dynamic characteristics of terminal-user requests in mobile edge networks, we develop a dynamic cache update method LS-TD3, which combines Long Short-Term Memory (LSTM) and Twin Delayed Deep Deterministic policy gradient (TD3). Specifically, we integrate the LSTM layer into the policy model framework of reinforcement learning to better predict the content popularity from dynamic time data, thus improving the accuracy of cache decision making. To further reduce computational complexity and enhance overall system performance, we employ a distributed optimization strategy to improve the dynamic caching decision process. Extensive experimental results demonstrate the superiority of the proposed algorithm in achieving inter-node load balancing and minimizing caching costs.