Achieving High Capacity Transmission With N-Dimensional Quasi-Fractal UCA

TL;DR

This paper introduces an N-dimensional quasi-fractal UCA antenna design and associated OAM multiplexing schemes that surpass traditional limits, enabling higher spectrum efficiency in wireless communications.

Contribution

The paper proposes a novel N-dimensional quasi-fractal UCA antenna structure and OAM multiplexing schemes that exceed the conventional OAM mode limits set by array-element count.

Findings

Achieved higher spectrum efficiency compared to traditional array layouts.

Demonstrated the ability to surpass OAM mode limits with fixed array elements.

Optimized antenna layouts for maximum channel capacity.

Abstract

The vortex electromagnetic wave carried by multiple orthogonal orbital angular momentum (OAM) modes in the same frequency band can be applied to the field of wireless communications, which greatly increases the spectrum efficiency. The uniform circular array (UCA) is widely used to generate and receive vortex electromagnetic waves with multiple OAM-modes. However, the maximum number of orthogonal OAM-modes based on UCA is usually limited to the number of array-elements of the UCA antenna, leaving how to utilize more OAM-modes to achieve higher channel capacity with a fixed number of arrayelements as an intriguing question. In this paper, we propose an N-dimensional quasi-fractal UCA (ND QF-UCA) antenna structure in different fractal geometry layouts to break through the limits of array-elements number on OAM-modes number. We develop the N-dimensional OAM modulation (NOM) and demodulation (NOD) schemes for OAM multiplexing transmission with the OAM-modes number exceeding the array-elements number, which is beyond the traditional concept of multiple antenna based wireless communications. Then, we investigate different dimensional multiplexing transmission schemes based on the corresponding QF-UCA antenna structure with various array-element layouts and evaluate the optimal layout type and dimension to obtain the highest channel capacity with a fixed number of array-elements. Simulation results show that our proposed schemes can obtain a higher spectrum efficiency, surpassing those of alternative array-element layouts of QF-UCA and the traditional multiple antenna systems.