  Coded caching is able to exploit accumulated cache size and hence superior to
uncoded caching by distributing different fractions of a file in different
nodes. This work investigates coded caching in a large-scale small-cell network
(SCN) where the locations of small base stations (SBSs) are modeled by
stochastic geometry. We first propose a content delivery framework, where
multiple SBSs that cache different coded packets of a desired file transmit
concurrently upon a user request and the user decodes the signals using
successive interference cancellation (SIC). We characterize the performance of
coded caching by two performance metrics, average fractional offloaded traffic
(AFOT) and average ergodic rate (AER), for which a closed-form expression and a
tractable expression are derived, respectively, in the high signal-to-noise
ratio region. We then formulate the coded cache placement problem for AFOT
maximization as a multiple-choice knapsack problem (MCKP). By utilizing the
analytical properties of AFOT, a greedy but optimal algorithm is proposed. We
also consider the coded cache placement problem for AER maximization. By
converting this problem into a standard MCKP, a heuristic algorithm is
proposed. Analytical and numerical results reveal several design and
performance insights of coded caching in conjunction with SIC receiver in
interference-limited SCNs.
