Optimization of Signal Design for Poly-Polarization Multiplexing in Satellite Communications

A poly-polarization multiplexing (PPM) scheme, that simultaneously utilizes two orthogonal polarization signals to create virtual additional planes, has been studied to enhance the spectrum efficiency for fixed satellite communication in the Ku band (12, 14 GHz). In this paper, to further increase the spectrum efficiency, we propose an enhanced PPM (E-PPM) scheme. By formulating the generalized linear mapping for two orthogonal polarization planes, the proposed scheme derives the optimal E-PPM signal set that has the largest minimum Euclidean distance. As a fundamental study, this paper focuses on an AWGN channel, and we show the achievable performance of the proposed scheme. In the computer simulations assuming no depolarization effects, we show that the E-PPM scheme reduces the required E_b/N₀ by 1.80 dB and 0.70 dB at BER =10^-7 compared with the conventional orthogonal polarization multiplexing (OPM) and PPM scheme, respectively.