  Multi-antenna coded caching is known to combine a global caching gain that is
proportional to the cumulative cache size found across the network, with an
additional spatial multiplexing gain that stems from using multiple
transmitting antennas. However, a closer look reveals two severe bottlenecks;
the well-known exponential subpacketization bottleneck that dramatically
reduces performance when the communicated file sizes are finite, and the
considerable optimization complexity of beamforming multicast messages when the
SNR is finite. We here present an entirely novel caching scheme, termed
\emph{cyclic multi-antenna coded caching}, whose unique structure allows for
the resolution of the above bottlenecks in the crucial regime of many transmit
antennas. For this regime, where the multiplexing gain can exceed the coding
gain, our new algorithm is the first to achieve the exact one-shot linear
optimal DoF with a subpacketization complexity that scales only linearly with
the number of users, and the first to benefit from a multicasting structure
that allows for exploiting uplink-downlink duality in order to yield optimized
beamformers ultra-fast. In the end, our novel solution provides excellent
performance for networks with finite SNR, finite file sizes, and many users.
