Enhanced Polarized Spatial Modulation With Optimal Power Allocation

초록

This article proposes two modulation schemes-binary polarized spatial modulation (BPSM) and permutation-based polarized spatial modulation (PPSM)-for multi-input multi-output systems employing polarized antennas. Unlike conventional spatial modulation techniques, which rely on partial antenna activation, the proposed schemes utilize all available transmit antennas with distinct polarization activation patterns to enhance spectral efficiency (SE) while reducing inter-antenna correlation. In BPSM, spatial bits are mapped to binary polarization states using dual-polarized antennas without permutations. PPSM extends this concept by employing permutation-based mapping over multiple polarization states and antennas, thereby allowing richer index information, particularly in systems with more than two polarization states or numerous transmit antennas. To enhance performance, singular value decomposition and particle swarm optimization are employed for optimal power allocation, maximizing channel capacity while adhering to practical constraints. Because of the high complexity of maximum likelihood detection, orthogonal matching pursuit is adopted as a low-complexity sparse recovery algorithm tailored to the inherent sparsity of the transmitted signal structure. The proposed schemes are analytically and numerically evaluated under Rayleigh and Rician fading channels by considering channel estimation errors and correlation effects. The results show that BPSM and PPSM offer favorable trade-offs between the SE and bit error rate, outperforming traditional spatial modulation schemes using both unpolarized and polarized antennas.

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