Figure 2

The feature distribution of five STBCs in the first three-dimensional spaces. It illustrates the feature distribution of five STBCs in the three-dimensional spaces mapped by Amari1, Amari2, and Amari5. The number of received samples, the type of modulation, the number of Monte Carlo trials and the signal-to-noise ratio are N=2048, QPSK, 50 times, and 20 dB, respectively. It shows that SM and Alamouti cluster at different places in the three-dimensional spaces mapped by Amari1, Amari2, and Amari5.