I have a question about using MIMO with DS-CDMA. suppose we are using 4 TX
antennas, and 4 RX
antennas, then the Reyleigh channel generated randomly of MIMO system will be of dimension H = [4x4]
, assuming also the transmitted signal using QAM modulation is x
done as below:
x =
[0.7 + 0.7i;
0.7 - 0.7i;
-0.7 + 0.7i;
-0.7 -0.7i];
So the received signal r
is supposed to be r = H*x
, which is of dimension of [4x1].
Now, suppose we are spreading that signal with PN/walsh code of dimension [4x1], by using the function of "kron"
in MATLAB, so the dimension of the new transmitted signal will be [16x1], equivalent that x_1 = kron(x,c);
where c
is the code used to spread the signal before transmission.
My question is, how can we transmit that signal after spreading it x_1
over the noted channel H
of dimension H with dimension [4x4]
?
Thank you
r = reshape(H*reshape(x_1,4,[]),[],1);
This assumes channelH
does not change during the transmission of 16 symbols ofx_1
. $\endgroup$