Optimal Scheduling of Caching in Gaussian Broadcast Channel with Common Information
Zhiyuan Lin, Wei Chen · 2018
Joint pushing and caching (JPC) is a promising approach to achieve high energy efficiency in content delivery systems. However, when content files are delivered in Gaussian broadcast channel, the optimal JPC policy that minimizes the transmission energy is still unknown. This paper focuses on the optimal JPC policy design in Gaussian broadcast channel, where the base station is capable of pushing private and common messages simultaneously. By pushing common messages to cache- enabled users, the transmission energy can be reduced, because the asynchronous requests for the same content file can be served by a single transmission. By analyzing the structure of the optimal policy under the constraints of buffer sizes and users' requests, we find that the pushing rate of the optimal policy remains unchanged between consecutive time instants corresponding to request times and request deadlines. Based on the structure of optimal pushing rate, we present a finite- dimension convex optimization problem, whose solution can be used to construct an optimal JPC policy.