Delay Analysis in Full-Duplex Heterogeneous Cellular Networks

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 that 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 in modern cellular networks. In this paper, by utilizing tools from the stochastic geometry, we analyze the local delay for downlink channel, which is typically defined as the mean number of required time slots for a successful communication. Given imperfect self-interference 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. Further, we aim to investigate the energy efficiency 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.