Fig. 1. Mapping rule diagram of MTO-PS-44QAM

Fig. 2. Constellation probability distribution diagram. (a) UD-64QAM; (b) MTO-44QAM

Fig. 3. Coherent RoF system based on Polar-PS-44QAM

Fig. 4. BER curves for different fiber lengths

Fig. 5. Constellation diagrams of 64QAM. (a) BTB; (b) 10 km; (c) 20 km

Fig. 6. Constellation diagrams of MTO-44QAM. (a) BTB; (b) 10 km; (c) 20 km

Fig. 7. Received optical power variation curves. (a) BTB; (b) 20 km

Fig. 8. Received optical power variation curve

Fig. 9. Signal error rate curves change with OSNR