Hi,

I want to estimate the soft symbols from LLRs coming from Decoder using the tanh function. The question is how are the bits mapped to symbols let say for 16-QAMⁱ:

In the specification it is written that the bits b(i),b(i+1),b(i+2),b(i+3) are mapped to the I and Q as for instance:

I Q
0000 1/sqrt(10) 1/sqrt(10)

0001 1/sqrt(10) 3/sqrt(10)

0010 3/sqrt(10) 1/sqrt(10)

0011 3/sqrt(10) 3/sqrt(10)

The question is: which of the bits b(i),b(i+1),b(i+2),b(i+3) is mapped to the I and which to Q. Or correct me If I am wrong: I think that b(i) and b(i+2) are mapped to I, and b(i+1) and b(i+3) mapped to Q.

Any sugestion?

Thanks in advance,
Flo