  In this paper, a novel hybrid-duplex scheme based on received power is
proposed for heterogeneous networks (HetNets). In the proposed scheme, the
duplex mode (half- or full-duplex) of each user is switchable according to the
received power from its serving base station (BS). The
signal-to-interference-plus-noise-ratio (SINR) and spectral efficiency are
analyzed for both downlink and uplink channels by using the tools of
\emph{inhomogeneous} Poisson point process. Furthermore, determining power
threshold for duplex mode switching is investigated for sum rate maximization,
which is formulated as a nonlinear integer programming problem and a greedy
algorithm is proposed to solve this problem. The theoretical analysis and the
proposed algorithm are evaluated by numerical simulations. Simulation results
show that the proposed hybrid-duplex scheme outperforms the half-duplex or
full-duplex HetNet schemes.
