  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.
