  Exploiting the millimeter wave (mmWave) band has recently attracted
considerable attention as a potential solution to widespread deployment of
device-to-device (D2D) communication challenges, namely, spectrum scarcity and
interference. However, its directional nature makes the utilization of mmWave
band a challenging task as it requires careful beam alignment between the D2D
transmitter and receiver. In this paper, we investigate the impact of
inaccurate angle-of-arrival (AoA) estimation as a beam alignment impairment on
the performance of a directional mmWave D2D network. We have used tools from
stochastic geometry to quantify the signal-to-interference-plus-noise ratio
(SINR) coverage probability in the presence of beam misalignment, which can be
applied to evaluate D2D network performance. Moreover, the analytical results
are verified to be reliable and effective through extensive simulations.
Finally, the coverage probability of the D2D network with erroneous beam
alignment is compared to the network with perfect beam alignment. The numerical
results indicate that the beam misalignment can lead to significant losses in
the network's coverage probability.
