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[Discuss-gnuradio] Problem in designing Coded OFDM Rxr (using, trellis-v

From: Achilleas Anastasopoulos
Subject: [Discuss-gnuradio] Problem in designing Coded OFDM Rxr (using, trellis-viterbi )
Date: Fri, 12 Nov 2010 14:23:04 -0500
User-agent: Mozilla/5.0 (Windows; U; Windows NT 6.0; en-US; rv: Gecko/20101027 Thunderbird/3.1.6

The channel decoding should be  performed on the output of ofdm_demod
block(ofdm_frame_sink ; the last block   that produces demodulated OFDM
symbols). But, the combined_ viterbi block performs the demodulation of BPSK
or QPSK based on the signal constellation and provides appropriate metrics
to viterbi_algorithm.

This is NOT true. The Viterbi block (combined or not) can work with a number of different metrics (eg, symbol wise Hamming distance!)
So you can implement your approach with this block as well.

In fact this kind of modularity was the MAIN design feature of the gr-trellis!

Of course, this does not mean that your "approach" is not going to work; indeed you are trying to perform
soft-input decoding which is better.

let me know if you have further problems with that,

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