# Device-to-Device Communications in Millimeter Wave Band: Impact of Beam Alignment Error

## TL;DR

This paper analyzes how beam alignment errors impact the performance of millimeter wave device-to-device networks, using stochastic geometry to quantify coverage probability and demonstrating significant performance degradation due to misalignment.

## Contribution

It provides an analytical framework to evaluate the effects of beam misalignment in mmWave D2D networks, validated by extensive simulations.

## Key findings

- Beam misalignment causes notable coverage probability loss.
- Analytical models match simulation results.
- Performance degradation increases with misalignment severity.

## Abstract

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.