Hi Jason,
I understand that you want to know how to perform BPSK demodulation on a sequence that has been transmitted through an AWGN channel. You have already modulated the sequence using BPSK and added noise to it.
Understanding BPSK Demodulation: BPSK demodulation involves detecting the transmitted bits from the received noisy signal. The process is simple: if the received signal is greater than zero, the bit is '1'; otherwise, it is '0'.
Noise Addition in the Channel: You added noise using the equation
y = u_BPSK + sqrt(N0/2)*(randn(size(u_BPSK))+i*randn(size(u_BPSK)));
This simulates the effect of an AWGN channel.
Demodulation Process:
First, you need to strip the imaginary part (if any) because BPSK is a real-valued modulation scheme.
Then, make a decision based on the sign of the real part of the received signal.
Begin by removing any imaginary components.
y_real = real(y);
Next, demodulate by checking the sign of the real part.
u_demodulated = y_real > 0;
Convert logical array to binary.
u_demodulated = double(u_demodulated);
Final Output: The demodulated sequence should match the original sequence, barring any errors introduced by the noise.
Refer to the documentation of "BPSK Modulation" for more details: https://www.mathworks.com/help/comm/ref/comm.bpskmodulator-system-object.html
Refer to the documentation of "AWGN Channel" for more details: https://www.mathworks.com/help/comm/ref/comm.awgnchannel-system-object.html
Refer to the documentation of "randn" function for more details: https://www.mathworks.com/help/matlab/ref/randn.html
Hope this helps!
