Dear all,
I am new to GNU Radio. I am building a transceiver with turbo encoder and FQPSK modulator. At the receiver, FQPSK demodulator softly demodulates the received signals with BCJR algorithm (FQPSK can be viewed as a two-bit input TCM with 16 states). I simulated the system using C++ code. The length of a frame into the turbo encoder is 1024. The generator polynomial is (013, 015). 8 iterations are taken. The three metrics of alpha, beta and gamma are calculated by using LUT to speed up the simulation. But I found that it still is a little bit slow. The turbo decoding operation of a frame takes about 0.064s (the simulation runs on a computer with 2 CPU of 3.0GHz and 2G memory). So I think if the turbo decoding is done by software, the throughput will be rather slow.
I checked the mailing list in 2006-05, in which it is said that throughput is very slow with extension to turbo decoding. But I am still wondering with some easy improvements, the throughput can be increased significantly. Further, if iterative phase synchronization is done by software, the receiving time of a frame will be intolerable. So I wonder whether the software define radio is suited for the transceiver that I mentioned above and GNU Radio is really real-time.
thanks
Neil
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