Performance-optimized Opportunistic Routing with Temporal-spatial Awareness and Collaborative Caching
— Opportunistic networks enable communication in infrastructure-deficient scenarios such as IoT deployment and disaster rescue through node mobility. However, existing routing protocols relying solely on contact frequency neglect link duration, leading to unstable transmission and inefficient caching. This paper proposes PORTAC, a historical contact–enhanced collaborative cache routing mechanism integrating contact stability–aware routing and multi-level cache scheduling. A spatio-temporal Contact Stability Index (CSI) evaluates link quality via duration-based logarithmic gain and historical context, while a core–radiation–edge cache hierarchy manages messages by value, forwarding count, and lifetime. Simulations on the ONE platform show that PORTAC increases delivery ratio by over 10.6% compared with PropheRouter, enhancing efficiency in dynamic networks.