  Caching in multi-cell networks faces a well-known dilemma, i.e., to cache
same contents among multiple edge nodes (ENs) to enable transmission
cooperation/diversity for higher transmission efficiency, or to cache different
contents to enable content diversity for higher cache hit rate. In this work,
we introduce a partition-based caching to exploit the tradeoff between
transmission diversity and content diversity in a multi-cell edge caching
networks with single user only. The performance is characterized by the system
average outage probability, which can be viewed as the sum of the cache hit
outage probability and cache miss probability. We show that (i) In the low
signal-to-noise ratio(SNR) region, the ENs are encouraged to cache more
fractions of the most popular files so as to better exploit the transmission
diversity for the most popular content; (ii) In the high SNR region, the ENs
are encouraged to cache more files with less fractions of each so as to better
exploit the content diversity.
