# WFRFT-aided Power-efficient Multi-beam Directional Modulation Schemes Based on Frequency Diverse Array

## TL;DR

This paper introduces power-efficient multi-beam directional modulation schemes using weighted fractional Fourier transform (WFRFT) based on frequency diverse arrays, enhancing security and efficiency in wireless transmissions.

## Contribution

It proposes novel WFRFT-based multi-beam DM schemes that improve power efficiency and security over traditional AN-DM methods, applicable to both cooperative and independent receivers.

## Key findings

- WFRFT schemes outperform conventional AN-DM in power efficiency
- Security is maintained even with close or collocated eavesdroppers
- Supports independent transmissions with different modulations

## Abstract

The artificial noise (AN) aided multi-beam directional modulation (DM) technology is capable of wireless physical layer secure (PLS) transmissions for multiple desired receivers in free space. The application of AN, however, makes it less power-efficient for such a DM system. To address this problem, the weighted fractional Fourier transform (WFRFT) technology is employed in this paper to achieve power-efficient multi-beam DM transmissions. Specifically, a power-efficient multi-beam WFRFT-DM scheme with cooperative receivers and a power-efficient multi-beam WFRFT-DM scheme with independent receivers are proposed based on frequency diverse array (FDA), respectively. The bit error rate (BER), secrecy rate, and robustness of the proposed multi-beam WFRFT-DM schemes are analyzed. Simulations demonstrate that 1) the proposed multi-beam WFRFT-DM schemes are more power-efficient than the conventional multi-beam AN-DM scheme; 2) the transmission security can also be guaranteed even if the eavesdroppers are located close to or the same as the desired receivers; and 3) the proposed multi-beam WFRFT-DM schemes are capable of independent transmissions for different desired receivers with different modulations.