  Heterogeneous networks (HetNets) as a combination of macro cells and small
cells are used to increase the cellular network's capacity, and present a
perfect solution for high-speed communications. Increasing area spectrum
efficiency and capacity of HetNets largely depends on the high speed of
backhaul links. One effective way which is currently utilized in HetNets is the
use of full-duplex (FD) technology that potentially doubles the spectral
efficiency without the need for additional spectrum. On the other hand, one of
the most critical network design requirements is delay, which is a key
representation of the quality of service (QoS) in modern cellular networks. In
this paper, by utilizing tools from the stochastic geometry, we analyze the
local delay for downlink (DL) channel, which is typically defined as the mean
number of required time slots for a successful communication. Given imperfect
self-interference (SI) cancellation in practical FD communications, we utilize
duplex mode (half-duplex (HD) or FD) for each user based on the distance from
its serving base station (BS). Further, we aim to investigate the energy
efficiency (EE) for both duplexing modes, i.e., HD and FD, by considering local
delay. We conduct extensive simulations to validate system performance in terms
of local delay versus different system key parameters.
