Fig. 1. O-OFDM-IM system model using step-by-step signal mapping method

Fig. 2. Flow chart of optimal constellation graph search algorithm

Fig. 3. BER of (4, 2) O-OFDM-IM system with sub-carrier selection algorithm

Fig. 4. Comparison of BER performance between traditional constellation and optimal constellation of (4, 1) system

Fig. 5. (4, 1) System constellation of transmitter and receiver in 16QAM format under weak turbulence

Fig. 6. (4, 1) System constellation of transmitter and receiver in 16QAM format under strong turbulence

Fig. 7. 16QAM eye diagram of (4, 1) system in weak turbulence

Fig. 8. 16QAM format eye diagram of (4, 1) system in strong turbulence

Fig. 9. BER of systems under different number of active subcarriers

Fig. 10. BER of the system using this method and other mapping methods