  Recently, edge caching and multicasting arise as two promising technologies
to support high-data-rate and low-latency delivery in wireless communication
networks. In this paper, we design three transmission schemes aiming to
minimize the delivery latency for cache-enabled multigroup multicasting
networks. In particular, full caching bulk transmission scheme is first
designed as a performance benchmark for the ideal situation where the caching
capability of each enhanced remote radio head (eRRH) is sufficient large to
cache all files. For the practical situation where the caching capability of
each eRRH is limited, we further design two transmission schemes, namely
partial caching bulk transmission (PCBT) and partial caching pipelined
transmission (PCPT) schemes. In the PCBT scheme, eRRHs first fetch the uncached
requested files from the baseband unit (BBU) and then all requested files are
simultaneously transmitted to the users. In the PCPT scheme, eRRHs first
transmit the cached requested files while fetching the uncached requested files
from the BBU. Then, the remaining cached requested files and fetched uncached
requested files are simultaneously transmitted to the users. The design goal of
the three transmission schemes is to minimize the delivery latency, subject to
some practical constraints. Efficient algorithms are developed for the
low-latency cloud-edge coordinated transmission strategies. Numerical results
are provided to evaluate the performance of the proposed transmission schemes
and show that the PCPT scheme outperforms the PCBT scheme in terms of the
delivery latency criterion.
