  There is a consensus in the literature that cell-switching is a viable
solution to tackle the draconian increase in the energy consumption of cellular
networks. Although the literature is full of works addressing the energy
consumption problem via cell-switching, where small cells with low or no load
are turned off and the traffic is offloaded to either adjacent base stations or
macro cells, in terrestrial communication networks, they may not be feasible
when there is either a lack of infrastructure or insufficient capacity due to
high demand. The integration of non-terrestrial networks (NTN) into the
cell-switching process can be considered as a visionary approach to handle this
problem. In this regard, high altitude platform station (HAPS) draws
considerable attention with its massive footprint, high capacity, and
ubiquitous connectivity. The aim of this study is to show the potential
benefits of using HAPS in cell-switching methods by being a bountiful host for
offloaded users from cell-switching operations. More specifically, HAPS is
included in the network so that it can increase the switching off opportunities
by providing extra coverage and capacity. The simulation results demonstrate
that a significant amount of reduction in energy consumption (as high as 16%)
is obtained while ensuring quality-of-service (QoS) requirements.
