Medium Access Control (MAC) and Physical Layer (PHY) - CISE

4-June-07 P1901_PRO_016_r0
Frequency
Domain
Inputs
Null
#1
#2
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#768
Null
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Null
#769
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#1536
Null
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0
1
2
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768
769
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1278
1279
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2046
2047
Submission page 59 UPA-OPERA
IDFT
0
1
2
.
.
768
769
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.
1278
1279
.
.
2046
2047
Figure 16 Subcarrier mapping
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Time
Domain
Outputs
After the inverse Fourier transform, the symbol is cyclically extended by NCP samples to create the “cyclic
prefix”.
3.7.2 Time domain windowing
The symbol may be multiplied by a windowing function to smooth transitions between the symbols. However,
the binding requirement is the spectral mask as detailed in 3.13. Time domain windowing is just one way to
achieve that goal. The implementer may use other methods to achieve the same goal such as time domain
filtering. Therefore the transition shape and duration (NW) are not specified here. In the particular case where
NW=0 the window degenerates into a rectangular pulse of value 1 and duration NSYM. In the general case where
NW>0 the window extends over more than one symbol (NSYM+NW) and the symbols overlap as shown in Figure
17. The general expression for the windowing function is given in Equation 22.
⎧
⎪
w(
n)
= ⎨
⎪ f ( N
⎪
⎩
W
f ( n)
1
+ N
SYM
0
− n −1)
Equation 22
And the windowing function fulfils the following condition:
N
SYM
f(n) +
f(N w - n -1)
= 1
0 ≤ n < NW
N w ≤ n < N SYM
≤ n < NW
+ N
elsewhere
SYM