  In cellular networks, the densification of connected devices and base
stations engender the ever-growing traffic intensity, and caching popular
contents with smart management is a promising way to alleviate such
consequences. Our research extends the previously proposed analysis of
three-tier cache enabled Heterogeneous Networks (HetNets). The main
contributions are threefold. We consider the more realistic assumption; that
is, the distribution of small base stations is following Poisson-Poisson
cluster processes, which reflects the real situations of geographic
restriction, user dense areas, and coverage-holes. We propose the allocation of
downlink data transmission capacity according to the cases of requested
contents which are either cached or non-cached in nearby nodes and elucidate
the traffic efficiency of the allocation under the effect of clustered
deployment of small base stations. The throughput and delay of the allocation
system are derived based on the approximated sojourn time of the Discriminatory
Processor Sharing (DPS) queue. We present the results of achievable efficiency
and such a system's performance for a better caching solution to the challenges
of future cellular networks.
