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ETSI ES 201 980 V4.1.2 (2017-04) |
8.4.3.2Cell gains
All time reference cells have a power gain of 2,0 in order to optimize performance at low signal to noise ratio, i.e. as,k = 
2 .
8.4.4Gain references
8.4.4.0Introduction
The gain reference cells are mainly used for coherent demodulation. These cells are scattered throughout the overall time frequency pattern and are used by the receiver to estimate the channel response.
8.4.4.1Cell positions
In a transmission frame, for the symbol of index s (ranging from 0 to Ns - 1), carriers for which index k belongs to the subsets as defined in table 58 are gain references.
Table 58: Carrier indices k for gain reference cells
Robustness mode |
Subset |
Condition |
Periodicity of the |
|
|
|
gain reference |
|
|
|
pattern |
A |
k = 2 + 4 × (s mod 5) + 20 × p |
p integer |
5 symbols |
|
|
kmin ≤ k ≤ kmax |
|
B |
k = 1 + 2 × (s mod 3) + 6 × p |
p integer |
3 symbols |
|
|
kmin ≤ k ≤ kmax |
|
C |
k = 1 + 2 × (s mod 2) + 4 × p |
p integer |
2 symbols |
|
|
kmin ≤ k ≤ kmax |
|
D |
k = 1 + (s mod 3) + 3 × p |
p integer |
3 symbols |
|
|
kmin ≤ k ≤ kmax |
|
E |
k = 2 + 4 × (s mod 4) + 16 × p |
p integer |
4 symbols |
|
|
kmin ≤ k ≤ kmax |
|
NOTE: The gain reference cell patterns have been chosen such that the edge carriers are included as gain reference cell positions.
Annex L gives some example figures illustrating the position of the gain reference cells.
8.4.4.2Cell gains
Gain reference cells mostly have a power gain of 2 (i.e. as,k = 
2 ), in order to optimize performances at low signal to noise ratio. However, gain reference cells close to the band lower and upper edges are over-boosted by a further power gain of 2 (i.e. overall power gain of 4, so that the amplitude as,k = 2 ) as defined in table 59.
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