  Over the past decade, the bulk of wireless traffic has shifted from speech to
content. This shift creates the opportunity to cache part of the content in
memories closer to the end users, for example in base stations. Most of the
prior literature focuses on the reduction of load in the backhaul and core
networks due to caching, i.e., on the benefits caching offers for the wireline
communication link between the origin server and the caches. In this paper, we
are instead interested in the benefits caching can offer for the wireless
communication link between the caches and the end users.
  To quantify the gains of caching for this wireless link, we consider an
interference channel in which each transmitter is equipped with an isolated
cache memory. Communication takes place in two phases, a content placement
phase followed by a content delivery phase. The objective is to design both the
placement and the delivery phases to maximize the rate in the delivery phase in
response to any possible user demands. Focusing on the three-user case, we show
that through careful joint design of these phases, we can reap three distinct
benefits from caching: a load balancing gain, an interference cancellation
gain, and an interference alignment gain. In our proposed scheme, load
balancing is achieved through a specific file splitting and placement,
producing a particular pattern of content overlap at the caches. This overlap
allows to implement interference cancellation. Further, it allows us to create
several virtual transmitters, each transmitting a part of the requested
content, which increases interference-alignment possibilities.
