# Physical Layer Security of Generalised Pre-coded Spatial Modulation with Antenna Scrambling

## TL;DR

This paper proposes a novel physical layer security method for GPSM using antenna scrambling and a security key, enhancing security by concealing information through scrambled symbols and comparing two scrambling techniques.

## Contribution

It introduces a security key-based approach for GPSM, employing antenna scrambling techniques (CAS and GAS) to improve physical layer security and quantify their security capacities.

## Key findings

- Security capacity is significantly improved with antenna scrambling.
- CAS and GAS offer different trade-offs in security performance.
- The proposed scheme effectively conceals information from eavesdroppers.

## Abstract

We now advocate a novel physical layer security solution that is unique to our previously proposed GPSM scheme with the aid of the proposed antenna scrambling. The novelty and contribution of our paper lies in three aspects: 1/ principle: we introduce a `security key' generated at Alice that is unknown to both Bob and Eve, where the design goal is that the publicly unknown security key only imposes barrier for Eve. 2/ approach: we achieve it by conveying useful information only through the activation of RA indices, which is in turn concealed by the unknown security key in terms of the randomly scrambled symbols used in place of the conventional modulated symbols in GPSM scheme. 3/ design: we consider both Circular Antenna Scrambling (CAS) and Gaussian Antenna Scrambling (GAS) in detail and the resultant security capacity of both designs are quantified and compared.