KAUST CTL researchers explores misalignment challenges in orbital angular momentum for RF wireless communication

1 min read · Sat, Feb 3 2024

Researchers Xiangyu Cui, Ki-Hong Park, and Mohamed-Slim Alouini from the CEMSE Division at King Abdullah University of Science and Technology (KAUST) have undertaken a focused study to investigate the impact of misalignment on the feasibility of orbital angular momentum (OAM) in radio frequency (RF) wireless communication. The study addresses misalignment challenges, emphasizing the potential applications of OAM as an additional degree of freedom alongside frequency, time, and space.

The research primarily targets RF wireless communication, especially in millimeter wave and terahertz frequencies. These frequencies are of particular interest due to their potential to optimize spectrum resources. However, the dominance of line-of-sight (LOS) channels at these frequencies poses challenges, exacerbated by the short wavelengths involved.

In contrast to conventional multiple input multiple output (MIMO) systems, even in LOS channels, OAM introduces an extra degree of freedom. However, the strict alignment requirements for free-space OAM, specifically the alignment between antenna arrays, present a significant hurdle. Notably, the researchers highlight that there has been limited exploration of the capacity analysis of OAM communication under random misalignment.

In their article, the researchers present closed-form intensity calculations for given misalignment values in both indoor and outdoor scenarios. The study meticulously explores the average capacity under 2-D Gaussian random misalignment through numerical analysis, validated with simulations. The research underscores the significance of understanding misalignment in the context of OAM communication.

Moreover, the team analyzes the relationship between average capacity and key system parameters such as array radii, signal-to-noise ratio, and misalignment distribution standard deviation for both indoor and outdoor situations. The study concludes by illustrating the effectiveness of the findings in the context of concentric circular arrays, emphasizing the potential impact of misalignment on the practical implementation of RF OAM communication systems.

Xiangyu Cui emphasized that "Our research sheds light on the critical aspect of misalignment in the deployment of OAM for RF wireless communication. By addressing this challenge, we hope to contribute to the realization of practical OAM communication systems, offering a unique perspective in the current landscape of wireless communication research."

More information can be found in the paper and the video given below:

X. Cui, K. -H. Park and M. -S. Alouini, "Effect of Random Misalignment in the Capacity of Millimeter-Wave OAM," in IEEE Open Journal of the Communications Society, doi: 10.1109/OJCOMS.2024.3361438.