mohatta2015.pdf
signal processing from power amplifier operation control point of view
signal processing from power amplifier operation control point of view
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112 MMSE AND ML DECISION FEEDBACK EQUALIZATION<br />
solved iteratively using Gauss/Seidel (SIC) [Jam96, Eld98] or Gauss/Jordan (PIC)<br />
[Eld98]. Forms of multistage PIC have been developed for TDM systems [ChaOl].<br />
SIC can be combined with LE for suppressing other signals [Koh90, Yoo93].<br />
Block DFE for CDMA can be found in [Kle93, Jun95b, Kle96].<br />
In CDMA, code averaging in designing a time-invariant FF can be found in<br />
[Cho04]. Use of a periodically time-varying FF based on code averaging can be<br />
found in [BotlOa].<br />
Group DFE has been examined primarily for CDMA systems [Var95, FaiOO].<br />
Code averaging can be used to simplify group detection for CDM DFE [BotlOa].<br />
When there are multiple receive antennas, signals can be grouped based on their<br />
spatial isolation [Pel07].<br />
PROBLEMS<br />
The idea<br />
5.1 Consider the Alice and Bob example. Suppose instead that r\ = —1 and<br />
r 2 — 4. Assume so = +1.<br />
a) What is the value of z\ and è\ with MMSE DFE?<br />
5.2 Consider the Alice and Bob example, MMSE DFE, and the case when SQ is<br />
the incorrect value (—1).<br />
a) What is the resulting decision variable for si (21)?<br />
b) What is the resulting decision variable for s 2 (z 2 )?<br />
5.3 Consider an example similar to Alice and Bob, in which r m = s m + 0.5s m _i.<br />
When detecting si using z\ — w\r\ + tt> 2 r 2 , what is the MSE as a function of wi<br />
and u> 2 ?<br />
More details<br />
5.4 Consider the MIMO scenario in which c — 10, d = 7, e = 9, and / — 6.<br />
a) What are the MMSE weights for detecting s\l<br />
b) What is the output SINR for sj?<br />
c) What is X2 in terms of r\ and r 2 ?<br />
5.5 Consider the general dispersive scenario with σ 2 = 10.<br />
a) With c = I, d = 0.2, use the MMSE DFE expressions in the text to<br />
determine the two forward weights and output S/(I + N).<br />
b) With c = 0.2, d = 1, use the MMSE DFE expressions in the text to<br />
determine the two forward weights and output S/(I + N).<br />
c) With c = 0.2, d = 1, what would the output S/(I + N) be if we ran an<br />
MMSE DFE backwards in time?<br />
5.6 For the general dispersive scenario, determine the SINR when a decision error<br />
is made in MMSE DFE.<br />
5.7 Consider the general MIMO case and (5.28).
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