As asked here, HERE if we have the signal
x = [0.7 + 0.7i; 0.7 - 0.7i; -0.7 + 0.7i; -0.7 -0.7i];
Which was spread over code
c and transmitted over channel
H whose dimension is [4x4], so the convolution of signal after spreading will become:
r = reshape(H*reshape(x,4,),,1);
comparing it with signal without spreading, it was
r = H*x;
That was explained well in the above link.
My question, suppose I am using Maximum likelihood estimation, in case if we didn't spread the signal, we will check the likelhood compared with the channel
H, but what's about after using spreading ? how will become the channel ? It supposed to be a vector of [16x1], is that right ? but how will it be ?