  Caching is an effective technique to improve user perceived experience for
content delivery in wireless networks. Wireless caching differs from
traditional web caching in that it can exploit the broadcast nature of wireless
medium and hence opportunistically change the network topologies. This paper
studies a cache-aided MIMO interference network with 3 transmitters each
equipped with M antennas and 3 receivers each with N antennas. With caching at
both the transmitter and receiver sides, the network is changed to hybrid forms
of MIMO broadcast channel, MIMO X channel, and MIMO multicast channels. We
analyze the degrees of freedom (DoF) of these new channel models using
practical interference management schemes. Based on the collective use of these
DoF results, we then obtain an achievable normalized delivery time (NDT) of the
network, an information-theoretic metric that evaluates the worst-case delivery
time at given cache sizes. The obtained NDT is for arbitrary M, N and any
feasible cache sizes. It is shown to be optimal in certain cases and within a
multiplicative gap of 3 from the optimum in other cases. The extension to the
network with arbitrary number of transmitters and receivers is also discussed.
