Hi alistu, now I am using Quadrature demodulator. and about constellation, I used four iterations with different BitsPerSymbol, 2, 4, 6, and 8 respectively. so 4QAM, 16 QAM, 64 QAM, and 256 QAM are used in the model.
Actually, I am still facing the same problem.
Please check the attached file.