1 This is an example of using gr-trellis in grc.
3 Two users are transmitting simultaneously using convolutionally encoded QPSK, each with power P1=alpha*P and P2=(1-alpha)*P.
4 The combined signal is observed in noise and four different receivers are considered:
5 1) A viterbi decoder decoding user 1 assuming user 2 is noise
6 2) A viterbi decoder decoding user 2 assuming user 1 is noise
7 3) A viterbi decoder decoding user 1 first
8 and then reencoding this signal, subtracting it from the observation
9 and then running a Viterbi decoder decoding user 2
10 4) A viterbi decoder decoding user 2 first
11 and then reencoding this signal, subtracting it from the observation
12 and then running a Viterbi decoder decoding user 1
14 You can change the signal to noise ratio P/sigma^2 and the allocation of power to the two users, alpha.