  This chapter focuses on the performance enhancement brought by the addition
of caching capabilities to full-duplex (FD) radios in the context of
ultra-dense networks (UDNs). More specifically, we aim at showing that the
interference footprint of such networks, i.e., the major bottleneck to overcome
to observe the theoretical FD throughput doubling at the network level, can be
significantly reduced thanks to edge caching. Fundamental results show that
most of the gain, as compared to their half-duplex (HD) counterparts, can be
achieved by such networks only if costly modifications to their infrastructure
are performed and/or if high-rate signaling is exchanged between user
equipments (UEs) over suitable control links. Therefore, we aim at proposing a
viable and cost-effective alternative to these solutions based on pre-fetching
locally popular contents at the network edge. We start by considering an
interference-rich scenario such as an ultra-dense FD small-cell network, in
which several non-cooperative FD base stations (BSs) serve their associated UEs
while communicating with a wireless backhaul node (BN) to retrieve the content
to deliver. We then describe a geographical caching policy aiming at capturing
local files popularity and compute the corresponding cache-hit probability.
Thereupon, we calculate the probability of successful transmission of a file
requested by a UE, either directly by its serving small-cell base station (SBS)
or by the corresponding BN: this quantity is then used to lower-bound the
throughput of the considered network. Our approach leverages tools from
stochastic geometry in order to guarantee both analytical tractability of the
problem and generality of the results. Our numerical simulations show that
shifting from cache-free to cache-aided FD small-cell networks yields a
remarkable performance improvement.
