上海科技大学知识管理系统

This paper considers the cache-aided multiple-input single-output (MISO) broadcast channel (BC), where a server with $L$ transmit antennas and containing $N$ equal-length files communicates to $K$ users through a wireless broadcast link, and each user has a cache memory of $M$ files. Multiple-antenna placement delivery array (MAPDA) is a combinatorial structure to design coded caching schemes with uncoded placement and one-shot linear delivery for this MISO BC problem. In this paper, by constructing a class of MAPDAs under cyclic placement, we obtain a new multi-antenna coded caching scheme with linear subpacketization, which achieves the optimal sum-DoF $KM/N+L$ when $M/N\leq L/K$. Compared to existing schemes which achieve the optimal sum-DoF, the proposed scheme achieves lower sum-DoF with significantly lower subpacketization when $M/N > L/K$ for some parameters. Compared to existing schemes under cyclic placement, the proposed scheme achieves higher sum-DoF with approximately the same subpacketization when $M/N > \displaystyle \max\{L/K, 1/2\}$.