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signal processing from power amplifier operation control point of view
signal processing from power amplifier operation control point of view
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170 ADVANCED TOPICS<br />
c) What are the three soft decision decoding metrics?<br />
d) What is the detected message number?<br />
7.4 Consider the Alice and Bob example. Suppose instead that z\ = —3 and<br />
¿2 = 4.<br />
a) What are the detected symbol values?<br />
b) Do the detected symbol values correspond to a valid message?<br />
c) What are the three soft decision decoding metrics?<br />
d) What is the detected message number?<br />
7.5 Consider the simple parity check code in which s;¡ = s\S2- Suppose we decide<br />
to use this code for error correction in the Alice and Bob example. Suppose the<br />
signed soft values are —1,3, — 2.<br />
a) Using Table 1.1, create a table of valid messages including values for s\,<br />
«2, and su. Assume that s ( i = +1 is a known symbol.<br />
b) Using soft decision decoding, add to the table decoding metrics for each<br />
possible message, using ζχ, Z2, and z,-j.<br />
c) Identify the decoded message.<br />
7.6 Consider the Alice and Bob example. Suppose instead that r\ = — 1 and<br />
Γ2 = 4. Assume s ( > = +1.<br />
a) Form a table of message metrics for only valid combinations of s\ and s 2 -<br />
b) Which metric is best? What is the detected sequence?<br />
7.7 Consider the Alice and Bob example. Suppose instead that r\ = — 1 and<br />
Γ2 = 4. Assume s () = +1. Suppose a parity check symbol s 3 = s\s 2 was also<br />
transmitted and r.i = 2.<br />
a) Form a table of message metrics for only valid combinations of s\, s 2 , and<br />
s.-j.<br />
b) What is the detected message number?<br />
More details<br />
7.8 Consider the Alice and Bob example and suppose we know that so = +1<br />
because it is a pilot symbol.<br />
a) Find the two symbol metrics for s 2 using Table 6.1.<br />
b) Did the MAPSD detected value for s 2 change?<br />
c) Compute the ratio of the symbol metrics, with the larger one in the numerator.<br />
Do the same for the case when s» was not known. What happened<br />
to the ratio when we added the information that so = +1?<br />
7.9 Consider the Alice and Bob example. Using the normalized sequence metrics<br />
in Table 7.4, compute the two symbol metrics for S2-<br />
7.10 Consider the Alice and Bob example. Suppose instead that r\ = — 1 and<br />
r 2 = 4. Assume SQ = +1. Consider the MLSD tree, except only valid message<br />
branches are allowed.<br />
a) What are the two path metrics after processing Γχ?
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