# Polarization Shift Keying (PolarSK): System Scheme and Performance Analysis

## TL;DR

This paper introduces Polarization Shift Keying (PolarSK), a novel modulation scheme for SIMO systems that leverages polarization states to enhance spectral efficiency, with analytical performance bounds and low-complexity detection algorithms.

## Contribution

The paper proposes a new PolarSK modulation scheme using polarization states for increased multiplexing in single-RF MIMO systems, along with performance analysis and detection algorithms.

## Key findings

- PolarSK outperforms existing dual-polarized and uni-polarized schemes.
- Analytic upper bounds on bit error probability are derived.
- Proposed detection algorithms reduce computational complexity.

## Abstract

Single-Radio-Frequency (RF) Multiple-Input-Multiple-Output (MIMO) systems such as the spatial modulation (SM) system and the space shift keying (SSK) system have been proposed to pursue a high spectral efficiency while keeping a low cost and complexity transceiver design. Currently, polarization domain resource has been introduced to the single-RF MIMO system to reduce the size of the transmit antenna array and provide 1 bit per channel use (bpcu) multiplexing gain. Nevertheless, the polarization domain resource still has the potential to provide a higher multiplexing gain in the polarized single-RF MIMO system. In this paper, we propose a generalized polarization shift keying (PolarSK) modulation scheme for a SIMO system that uses the polarization states in the dual-polarized transmit antenna as an information-bearing unit to increase the overall spectral efficiency. At the receive end, the maximum likelihood (ML) detector is employed to demodulate the received signal. A closed form union upper bound on the average bit error probability (ABEP) of PolarSK system with the optimum maximum likelihood (ML) receiver is deduced under fading channels. To reduce the computational complexity of the receiver, a linear successive interference cancellation (SIC) detection algorithm and a sphere-decoding (SD) detection algorithm are proposed. On the basis of analytic results and simulations, performances of the proposed PolarSK systems in terms of computational complexity and ABEP are analyzed. Numerical results show that the proposed PolarSK scheme performs better than state of the art dual-polarized/uni-polarized SM schemes.