  In milimeter wave heterogenous networks with integrated access and backhaul
(mABHetNets), a considerable part of spectrum resources are occupied by the
backhaul link, which limits the performance of the access link. In order to
overcome such backhaul "spectrum occupancy", we introduce cache in mABHetNets.
Caching popular files at small base stations (SBSs) can offload the backhaul
traffic and transfer spectrum from the backhaul link to the access link. To
achieve the optimal performance of the cache-enabled mABHetNets, we first
analyze the signal-to-interference-plus-noise ratio (SINR) distribution and
derive the average potential throughput (APT) expression by stochastic
geometric tools. Then, based on our analytical work, we formulate a joint
optimization problem of cache decision and spectrum partition to maximize the
APT. Inspired by the block coordinate descent (BCD) method, we propose a joint
cache decision, spectrum partition and power allocation (JCSPA) algorithm to
find the optimal solution. Simulation results show the convergence and
enhancement of the proposed algorithm. Besides, we verify the APT under
different parameters and find that the introduction of cache facilitates the
transfer of backhaul spectrum to access link. Jointly deploying appropriate
caching capacity at SBSs and performing specified spectrum partition can bring
up about 90% APT gain in mABHetNets.
