I working on an implementation of a linear precoding algorithm for MIMO OFDM system and I have an issue with symbol estimation part. Let me briefly explain what I am doing:
- H- channel matrix
Nr x Nt x N( received and transmitted antenna, subcarrier)
- x- input data (
F x Nt x N) ( streams x Tx antenna x subcarrier)
I have started with a calculation linear precoding matrix -V:
1) I have computed SVD for each subcarrier Hn (
Nr x Nt)
2) "x" has been split into streams and each vector Nt x 1 has benn used for " V *x_vector".
I have made the same calculation for each stream and get a precoded input data "D (
Fx Nt x N) "
Then I use "D" in the standard OFDM block diagram(IFFT, add CP, channel, FFT, remove CP) and get a received data "R (
Fx Nr x N)"
Now to estimate the input data, I have split into streams, then vectors Nr x 1 and take a product U [svd(Hn)] with Nr x 1 and after a result has been ./diag(S) I have exected to get better performance of the system with precoding, but SER I have got bigger than without precoded algorithm.
Could anyone suggest where I have mistaken?