Title: Degrees of Freedom in Cached MIMO Relay Networks With Multiple Base Stations,
Abstract: The ability of physical layer relay caching to increase the degrees of
freedom (DoF) of a single cell was recently illustrated. In this paper, we
extend this result to the case of multiple cells in which a caching relay is
shared among multiple non-cooperative base stations (BSs). In particular, we
show that a large DoF gain can be achieved by exploiting the benefits of having
a shared relay that cooperates with the BSs. We first propose a cache-assisted
relaying protocol that improves the cooperation opportunity between the BSs and
the relay. Next, we consider the cache content placement problem that aims to
design the cache content at the relay such that the DoF gain is maximized. We
propose an optimal algorithm and a near-optimal low-complexity algorithm for
the cache content placement problem. Simulation results show significant
improvement in the DoF gain using the proposed relay-caching protocol.