# Energy-efficient Alternating Iterative Secure Structure of Maximizing Secrecy Rate for Directional Modulation Networks

## TL;DR

This paper proposes an energy-efficient alternating iterative method to optimize beamforming and power allocation in directional modulation networks, significantly enhancing secrecy rate performance especially at high SNRs.

## Contribution

It introduces a novel alternating iterative structure that jointly optimizes beamforming and power allocation for improved secrecy rate in DM networks.

## Key findings

- Rapid convergence within two or three iterations.
- Outperforms null-space projection strategy at medium and high SNR.
- Effective especially with fewer antennas at the transmitter.

## Abstract

In a directional modulation (DM) network, the issues of security and privacy have taken on an increasingly important role. Since the power allocation of confidential message and artificial noise will make a constructive effect on the system performance, it is important to jointly consider the relationship between the beamforming vectors and the power allocation (PA) factors. To maximize the secrecy rate (SR), an alternating iterative structure (AIS) between the beamforming and PA is proposed. With only two or three iterations, it can rapidly converge to its rate ceil. Simulation results indicate that the SR performance of proposed AIS is much better than the null-space projection (NSP) based PA strategy in the medium and large signal-to-noise ratio (SNR) regions, especially when the number of antennas at the DM transmitter is small.