  Integrating coded caching (CC) into multi-input multi-output (MIMO) setups
significantly enhances the achievable degrees of freedom (DoF). We consider a
cache-aided MIMO configuration with a CC gain $t$, where a server with $L$
Tx-antennas communicates with $K$ users, each equipped with $G$ Rx-antennas.
Similar to existing works, we also extend a core CC approach, designed
initially for multi-input single-output (MISO) scenarios, to the MIMO setup.
However, in the proposed MIMO strategy, rather than replicating the transmit
scheme from the MISO setup, the number of users $\Omega$ served in each
transmission is fine-tuned to maximize DoF. As a result, an optimized DoF of
${\max_{\beta, \Omega }}{\Omega \beta}$ is achieved, where ${\beta \le
\mathrm{min}\big(G,L \binom{\Omega-1}{t}}\Big/{1 + (\Omega -
t-1)\binom{\Omega-1}{t}}\big)$ is the number of parallel streams decoded by
each user. For the considered MIMO-CC setup, we also introduce an effective
multicast transmit covariance matrix design for the symmetric rate maximization
objective solved iteratively via successive convex approximation (SCA).
Finally, numerical simulations verify the enhanced DoF and improved performance
of the proposed design.
