作者datagram (...)
看板comm_and_RF
標題[問題] Using 8PSK with viterbi soft-decoding
時間Sun Apr 16 22:34:10 2006
下面是網路上某人寫的，也剛好是我要問的問題
由於英文蠻淺的，所以我就不把它翻成中文：
I have this problem where I need to use 8PSK and convolutional
code rate 1/2. My problem is to do the soft-decision.
For example：
I have 9 bits generated, go into the 1/2 convolutional encoder
I will get 18 bits, then I do 8PSK modulator I will get 6 symbols,
then go into the channel and will received some values which have
been corrupted by the noise and fading.
Now with this 6 symbols (in complex number form),
if for hard decision we can get back three bits out of each symbols,
and altogether will be 18 bits, and the viterbi decoder will take 2 bits
and output 1-bits, then we will get back 9 bits.
But imagine for soft decision, how am I going to produce soft input
out of each symbols? I mean I need to have 3 soft outputs from each
symbol of this complex number, before it can go into the viterbi decoder?
Thank you.
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※ 編輯: datagram 來自: 140.112.252.68 (04/16 22:34)