Resolving the Feedback Bottleneck of Multi-Antenna Coded Caching

Multi-antenna cache-aided wireless networks were thought to suffer from a severe feedback bottleneck, since achieving the maximal Degrees-of-Freedom (DoF) performance required all served users for known transmission schemes. These costs match caching gains and thus scale with number of users. In context $L$ -antenna Multiple-Input Single Output broadcast channel notation="LaTeX">$K$ receivers, each having normalized cache size notation="LaTeX">$\gamma $ , we pair fundamentally novel algorithm together new information-theoretic converse identify optimal tradeoff between DoF performance, by showing that state information only notation="LaTeX">$C< L$ implies an one-shot linear notation="LaTeX">$C+K\gamma . As side consequence this, also now understand well notation="LaTeX">$L+K\gamma is in fact exactly optimal. practice, above means are able disentangle costs, unbounded at mere cost multiplexing gain. This further solidifies role boosting multi-antenna systems; can provide over downlink systems, no additional costs. The results extended include corresponding multiple transmitter scenario caches both ends.