This paper considers a cloud-RAN architecture with cache-enabled
multi-antenna Edge Nodes (ENs) that deliver content to cache-enabled end-users.
The ENs are connected to a central server via limited-capacity fronthaul links,
and, based on the information received from the central server and the cached
contents, they transmit on the shared wireless medium to satisfy users'
requests. By leveraging cooperative transmission as enabled by ENs' caches and
fronthaul links, as well as multicasting opportunities provided by users'
caches, a close-to-optimal caching and delivery scheme is proposed. As a
result, the minimum Normalized Delivery Time (NDT), a high-SNR measure of
delivery latency, is characterized to within a multiplicative constant gap of
3/2 under the assumption of uncoded caching and fronthaul transmission, and
of one-shot linear precoding. This result demonstrates the interplay among
fronthaul links capacity, ENs' caches, and end-users' caches in minimizing the
content delivery time.Comment: 9 pages, 3 figures, submitte