Angular and Temporal Correlation of V2X Channels Across Sub-6 GHz and mmWave Bands

TL;DR

This study investigates how propagation characteristics of V2X channels are correlated across sub-6 GHz and mmWave bands using ray tracing, revealing strong correlations especially in LOS scenarios, aiding in beam alignment and link reliability.

Contribution

The paper provides a detailed analysis of angular and temporal correlation across a wide frequency range for V2X channels, highlighting the coupling between sub-6 GHz and mmWave bands.

Findings

Strong temporal/angular correlation between 5.9 GHz and 28 GHz in LOS channels

Increased sparsity of channels at higher frequencies

Correlation diminishes in NLOS scenarios

Abstract

5G millimeter wave (mmWave) technology is envisioned to be an integral part of next-generation vehicle-to-everything (V2X) networks and autonomous vehicles due to its broad bandwidth, wide field of view sensing, and precise localization capabilities. The reliability of mmWave links may be compromised due to difficulties in beam alignment for mobile channels and due to blocking effects between a mmWave transmitter and a receiver. To address such challenges, out-of-band information from sub-6 GHz channels can be utilized for predicting the temporal and angular channel characteristics in mmWave bands, which necessitates a good understanding of how propagation characteristics are coupled across different bands. In this paper, we use ray tracing simulations to characterize the angular and temporal correlation across a wide range of propagation frequencies for V2X channels ranging from 900 MHz up to 73 GHz, for a vehicle maintaining line-of-sight (LOS) and non-LOS (NLOS) beams with a transmitter in an urban environment. Our results shed light on increasing sparsity behavior of propagation channels with increasing frequency and highlight the strong temporal/angular correlation among 5.9 GHz and 28 GHz bands especially for LOS channels.