In this work, we report simulations on a GaAs-AlGaAs gated nanowire resonant tunneling diode (RTD) for tunable terahertz communication applications. All calculations are performed with the self-consistent Non-Equilibrium Green's Function (NEGF) quantum transport formalism implemented in our in-house Nano-Electronic Simulation Software (NESS). Our simulations successfully capture the detailed picture of the quantum mechanical effects such as quantum confinement and resonant tunneling of electrons through barriers in such structures. Moreover, we report for the first time the correlation between the gate-bias voltage and the position of the resonant peak (VR) in the current - voltage characteristics. Such Vr, which is associated with tunneling effects in RTD, could lead to tunable terahertz generation and detection for communication applications. © 2020 The Japan Society of Applied Physics.