  Centralized coded caching and delivery is studied for a partially-connected
fog radio access network (F-RAN), whereby a set of H edge nodes (ENs) (without
caches), connected to a cloud server via orthogonal fronthaul links, serve K
users over the wireless edge. The cloud server is assumed to hold a library of
N files, each of size F bits; and each user, equipped with a cache of size MF
bits, is connected to a distinct set of r ENs; or equivalently, the wireless
edge from the ENs to the users is modeled as a partial interference channel.
The objective is to minimize the normalized delivery time (NDT), which refers
to the worst case delivery latency, when each user requests a single file from
the library. An achievable coded caching and transmission scheme is proposed,
which utilizes maximum distance separable (MDS) codes in the placement phase,
and real interference alignment (IA) in the delivery phase, and its achievable
NDT is presented for r = 2 and arbitrary cache size M, and also for arbitrary
values of r when the cache capacity is sufficiently large.
