Fig. 1. Principle of generation of polarization multiplexing millimeter-wave signal based on a dual-polarization Mach-Zehnder modulator, in which illustrations (a)-(c) are simplified spectra

Fig. 2. Experimental setup for fiber-wireless integration transmission of PDM-16QAM vector RF signal, in which illustrations (a) and (b) are FTM7981EDA and optical spectrum, respectively

Fig. 3. Received PDM-16QAM constellations at the baud rate of 6 Gbaud. X-polarization: (a) After down conversion; (b) after CMMA equalization; (c) after frequency-offset estimation; (d) after carrier phase estimation. Y-polarization: (e) after down conversion; (f) after CMMA equalization; (g) after frequency-offset estimation; (h) after carrier phase estimation

Fig. 4. BER of 6 Gbaud PDM-16QAM signal at different input powers into PD

Fig. 5. Frequency spectrum and constellations. (a) Frequency spectrum of 28 GHz vector RF signal; (b) demodulated constellation in X-polarization after DD-LMS equalization; (c) demodulated constellation in Y-polarization after DD-LMS equalization

Fig. 6. BER of PDM-16QAM signal at different baud rates

Fig. 7. BER of PDM-16QAM signal versus DD-LMS taps number