  A dense deployment of on-grid small cell base stations (SBSs) in a
heterogeneous cellular network (HCN) results in large power consumption which
can be reduced by utilizing harvested energy from scavenge sources. Recently, a
new layout for HCN with energy harvesting-SBSs (EH-SBSs) has been proposed to
reduce inter-cell interference and power consumption; and increase system
energy efficiency. In this paper, an energy efficient joint user association
and BS on-off scheme for an HCN having diverse energy source(s) is proposed,
which aims at utilizing the harvested energy efficiently in order to reduce the
on-grid power consumption. The scheme operates in two phases. First, it decides
which BS should be in off, sleep or active mode and iteratively updates its
transmit power based on energy arrival and consumption, to minimize
interference and on-grid power consumption. Secondly, for further reduction in
on-grid power consumption, the user discovers and associates itself with the
nearest available EH-SBS. The system energy consumption for the proposed scheme
is numerically evaluated using Monte Carlo simulations. Simulation results
reveal that the proposed scheme shows significantly better results as compared
to other schemes in the literature in terms of grid power consumption and
energy efficiency.
