MRC - demodulation of the transmitted signal

[saeddawoud]

MRC

Hello,

Suppose that we transmit a signal \[x(t)\] from one antenna, and recieved by \[N\] antennas, and combined using MRC technique. Now, what is postdetected signal \[y(t)\]?

We may say the following: Suppose that the received signal on the \[j^{th}\] receive antenna is \[f_j(t) = s_j(t)+n_j(t)\], where \[s_j(t)=h_j\, x(t) \]. Then, the postprocessed received signal at the destination will be

\[y(t)=\sum_{k=1}^N a_k \, f_k(t)\]

right?

But the question is: what is the values of \[\{a_k\}_{k=1}^N\]??

Thanks in advance

 

[farzad_m]

MRC

I assume you are talking about demodulation of the transmitted signal.
\alpha_k is define in a way to maximize the received SNR in the receiver hence the name MRC. for Gaussian noise, it can be shown that \alpha_k is equal to conj(h_j).
Also note that the receiver does not combine the signal the way that you wrote, it also uses matched filter: y(t)=sum{conj(h(j))*int(f_k(t)*s_j(t))}