Step 1: Generate a random binary 0 and 1 sequence of length N, call it {bn}. Keep N as a variable. You can choose N = 210, 215, 220. Example : bn=round(rand(1,N)). Step 2: Convert the Binary sequence {bn} into real-valued Symbols of 0,1,2,and 3, call it Sk. Uses MATLAB function ak=qammod(sk,4) to map the Symbols to a QPSK symbol sequence {ak). Step 3: Passing {ak} through an AWGN channel using function rk=awgn(ak,snr). rk = ak + nk, Generate your noise sequence such that the SNR 0:2:16dB. Step 4: Using function ŝk=qamdemod(rk,4) to demap {rk} to obtain an estimated sequence for Sk (with possible values 0,1,2,3). Step 5: Convert ŝk back to a binary sequence {ôn}, which is an estimated version of your original binary sequence {bn}. Step 6. Calculate and plot your BER versus SNR = 0:2:16dB using "semilogy". Add labels and titles to get nice-looking figures.
