  Recently, wireless edge caching has been emerged as a promising technology
for future wireless networks to cope with exponentially increasing demands for
high data rate and low latency multimedia services by proactively storing
contents at the network edge. Here, we aim to design efficient cache placement
and delivery strategies for an orthogonal frequency division multiple access
(OFDMA)-based cache-enabled heterogeneous cellular network (C-HetNet) which
operates in two separated phases: caching phase (CP) and delivery phase (DP).
Since guaranteeing fairness among mobile users (MUs) is not well investigated
in cache-assisted wireless networks, we first propose two delay-based fairness
schemes called proportional fairness (PF) and min-max fairness (MMF). The PF
scheme deals with minimizing the total weighted latency of MUs while MMF aims
at minimizing the maximum latency among them. In the CP, we propose a novel
proactive fairness and transmission-aware cache placement strategy (CPS)
corresponding to each target fairness scheme by exploiting the flexible
wireless access and backhaul transmission opportunities. Specifically, we
jointly perform the allocation of physical resources as storage and radio, and
user association to improve the flexibility of the CPSs. Moreover, In the DP of
each fairness scheme, an efficient delivery policy is proposed based on the
arrival requests of MUs, CSI, and caching status. Numerical assessments
demonstrate that our proposed CPSs outperform the total latency of MUs up to
27% compared to the conventional baseline popular CPSs.
