Figure 1:
Building blocks of IFFT based OFDM-IM system. IFFT, inverse fast Fourier transform; OFDM, orthogonal frequency division multiplexing; OFDM-IM, OFDM with index modulation.
Figure 2:
Building blocks of DWT based OFDM-IM system. DWT, discrete wavelet transform; OFDM, orthogonal frequency division multiplexing; OFDM-IM, OFDM with index modulation.
Table 1:
Values of α, κ and µ for various fading distribution
| Sl. No. | Distribution | α | κ | µ |
|---|---|---|---|---|
| 1 | Rayleigh | 2 | 0 | 1 |
| 2 | Rician | 2 | 1 | 1 |
| 3 | Nakagami-m | 2 | 0 | <1 |
| 4 | Gaussain | 2 | 0 | 0.5 |
| 5 | Weibull | 3.5 | 0 | 1 |
Table 2:
Simulation parameters for OFDM-IM system
| Sl. No. | Distribution | FFT based system | DWT based system |
|---|---|---|---|
| 1 | Number of symbols | 10,000 | 10,000 |
| 2 | FFT/DWT size | 64 | - |
| 3 | Modulation | M-QAM | M-QAM |
| 4 | Subcarriers | 512 | 512 |
| 5 | Cyclic prefix duration | 0.8 µs | - |
| 6 | Sampling frequency | 20 MHz | |
| 7 | Total symbol duration | 4 µs | |
| 8 | Subcarrier index | −26 to −1; +1 to +26 | |
| 9 | Subcarrier spacing | 312.5 KHz | |
| 10 | Mapping scheme | 8-QAM |
Figure 3:
CCDF curves for FFT & DWT based OFDM-IM system. CCDF, complementary cumulative distribution function; DWT, discrete wavelet transform; IFFT, inverse fast Fourier transform; OFDM, orthogonal frequency division multiplexing; OFDM-IM, OFDM with index modulation.
Figure 4:
BER curves for α = 2,κ = 0,µ =1 and α = 2,κ = 0,µ =0.5. BER, bit error rate.