Alpha fair coded caching

Abstract

The performance of existing coded caching schemes is sensitive to the worst channel quality, when applied to wireless channels. In this paper, we address this limitation in the following manner: in short-term, we allow transmissions to subsets of users with good channel quality, avoiding users with fades, while in long-term we ensure fairness across the different users. Our online delivery scheme combines (i) joint scheduling and power control for the fading broadcast channel, and (ii) congestion control for ensuring the optimal long-term average performance. By restricting the caching operations to decentralized coded caching proposed in the literature, we prove that our proposed scheme has near-optimal overall performance with respect to the long-term alpha fairness performance. By tuning the coefficient alpha, the operator can differentiate the user performance in terms of video delivery rates achievable by coded caching. We demonstrate via simulations that our scheme outperforms standard coded caching and unicast opportunistic scheduling, which are identified as special cases of our general framework.