Generation of Random Quaternary Signal with QAM Modulation and AWGN Channel Simulation

Generate a random quaternary signal, perform QAM modulation, transmit through an additive white Gaussian noise (AWGN) channel by adding white noise to the modulated signal using addition operation, simulate the impact of AWGN channel on signal transmission, demodulate the received signal at the receiver end, compare with the original signal to calculate bit error rate (BER). Vary the noise power to plot signal-to-noise ratio (SNR) versus BER curve, and compare performance curves with classmates to evaluate the advantages and disadvantages of different modulation schemes.