blade88
Junior Member level 2
Hello,
I want to simulate in Matlab a Time domain Decision Feedback Equalizer.
Let's call:
Nff the number of feedforward coefficients, W = [w1 w2 ... wNff]
Nbb the number of feedback coefficients, B = [b1 b2 .. bNbb]
k the time instant I sent N samples
d the delay of the equalizer.
I assume no oversampling and I haven't normalized the tx signal.
Also, suppose we know the W and B coefficients and that we have generated them
based either on ZF or MMSE criterion.
The steps I follow are these:
My question is how we decide from which symbols we substract?
Thank you in advance.
I want to simulate in Matlab a Time domain Decision Feedback Equalizer.
Let's call:
Nff the number of feedforward coefficients, W = [w1 w2 ... wNff]
Nbb the number of feedback coefficients, B = [b1 b2 .. bNbb]
k the time instant I sent N samples
d the delay of the equalizer.
I assume no oversampling and I haven't normalized the tx signal.
Also, suppose we know the W and B coefficients and that we have generated them
based either on ZF or MMSE criterion.
The steps I follow are these:
- Generate a Nx1 vector of M-QAM symbols (M=4/16/64). This is the Tx signal.
- Convolve this vector with a random frequency selective channel
and then add white noise.
- Convolve the received signal with the feedforward filter of the equalizer.
There, I discard the first d symbols, since if I send the samples at time k
[y(k) y(k+1) .... y(k+N)] , I will receive the samples k+d time later, meaning
[y(k+d) y(k+d+1).....y(k+d+N)].
- Convolve the Tx signal with the feedback filter, since we assume no errors
in the decisions of the detector device. The result is the influence of the past symbols.
- Substract the influence from the current symbols. Here I have the problem.
My question is how we decide from which symbols we substract?
Thank you in advance.
