Downstream power back-off for fiber to node applications
View Patent ↗There is provided a method of shaping PSD (Power Spectrum Density) of an FTTN (Fiber-To-The-Node) downstream signal from a disturber source to achieve spectral compatibility at an FTTN downstream victim with a downstream PSD from a reference source. The method includes receiving the downstream PSD from the reference source. The method further includes receiving an unshaped downstream PSD from the disturber source. The method further includes shaping the PSD of the FTTN downstream signal to have a substantially equivalent FEXT (Far-End Cross-Talk) into the FTTN downstream victim as the downstream PSD from the reference source.
1. A method of shaping PSD (Power Spectrum Density) of an FTTN (Fiber-To-The-Node) downstream signal from a disturber source so as to achieve spectral compatibility at an FTTN downstream victim with a downstream PSD from a reference source, said method comprising:
receiving said downstream PSD from said reference source;
receiving an unshaped downstream PSD from said disturber source;
shaping said PSD of said FTTN downstream signal to have a substantially equivalent FEXT (Far-End Cross-Talk) into said FTTN downstream victim as said downstream PSD from said reference source;
wherein said reference source is in an FTTB (Fiber-To-The-Building) system and said disturber source is in an FTTN system.
2. The method of claim 1 , wherein shaping uses:
γ
SM
2
(
f
)
=
MIN
{
γ
M
2
(
f
)
,
γ
M
1
(
f
)
·
1
1
+
L
B
·
1
H
(
f
,
L
)
2
}
,
wherein γ SM2 (f) is a shaped PSD of said FTTN downstream signal, γ M1 (f) is said downstream PSD from said reference source, γ M2 (f) is said unshaped downstream PSD from said disturber source, L is a distance from said disturber source to said reference source, B is a distance from said FTTN downstream victim to said reference source, f is a frequency of said FTTN downstream signal, and H(f, L) is a transfer function of a cable at a frequency equal to said f and having a length equal to said L.
3. The method of claim 1 , wherein said disturber source is an FTTN cabinet.
4. The method of claim 1 , wherein said reference source is a building.
5. The method of claim 1 , wherein said FTTN downstream signal is transmitted from said disturber source by a DSL modem.
6. The method of claim 5 , wherein said DSL modem is a VDSL modem.
7. The method of claim 1 , wherein said reference source is an FTTB cabinet in a building.
8. The method of claim 1 , wherein said downstream PSD is transmitted from said reference source by a VDSL modem.
9. A method of shaping PSD of an FTTN downstream signal from an FTTN cabinet to achieve spectral compatibility at an FTTN downstream victim with a downstream PSD from an FTTB cabinet in a building, said method comprising:
receiving said downstream PSD from said FTTB cabinet in said building;
receiving an unshaped downstream PSD from said FTTN cabinet;
shaping said PSD of said FTTN downstream signal using:
γ
SM
2
(
f
)
=
MIN
{
γ
M
2
(
f
)
,
γ
M
1
(
f
)
·
1
1
+
L
B
·
1
H
(
f
,
L
)
2
}
,
wherein γ SM2 (f) is a shaped PSD of said FTTN downstream signal, γ M1 (f) is said downstream PSD from said FTTB cabinet in said building, γ M2 (f) is said unshaped downstream PSD from said FTTN cabinet, L is a distance from said FTTB cabinet to said building, B is a distance from said FTTN downstream victim in said building to said FTTB cabinet, f is a frequency of said FTTN downstream signal, and H(f, L) is a transfer function of a cable at a frequency equal to said f and having a length equal to said L.
10. The method of claim 9 , wherein said shaped PSD of said FTTN downstream signal has a substantially equivalent FEXT (Far-End Cross-Talk) into said FTTN downstream victim in said building as said downstream PSD from said FTTN cabinet in said building.
11. The method of claim 9 , wherein said FTTN downstream signal from said FTTN cabinet is transmitted by a DSL modem at said FTTN cabinet.
12. The method of claim 11 , wherein said DSL modem is a VDSL modem.
13. The method of claim 9 , wherein said downstream PSD from said FTTB cabinet, is received from a VDSL modem.
14. A device for generating a shaped PSD of an FTTN downstream signal from a disturber source to achieve spectral compatibility at an FTTN downstream victim with a downstream PSD from a reference source, said device comprising:
wherein said device is configurable to receive said downstream PSD from said reference source;
wherein said device is further configurable to receive an unshaped downstream PSD from said disturber source;
wherein said device is further configurable to generate said shaped PSD of said FTTN downstream signal to have a substantially equivalent FEXT into said FTTN downstream victim as said downstream PSD from said reference source;
wherein said reference source is in an FTTB (Fiber-To-The-Building) system and said disturber source is in an FTTN system.
15. The device of claim 14 , wherein said device generates said shaped PSD of said FTTN downstream signal using:
γ
SM
2
(
f
)
=
MIN
{
γ
M
2
(
f
)
,
γ
M
1
(
f
)
·
1
1
+
L
B
·
1
H
(
f
,
L
)
2
}
,
wherein γ SM2 (f) is said shaped PSD of said FTTN downstream signal, γ M1 (f) is said downstream PSD from said reference source, γ M2 (f) is said unshaped downstream PSD from said disturber source, L is a distance from said disturber source to said reference source, B is a distance from said FTTN downstream victim to said reference source, f is a frequency of said FTTN downstream signal, and H(f, L) is a transfer function of a cable at a frequency equal to said f and having a length equal to said L.
16. The device of claim 14 , wherein said device is a DSL modem.
17. The device of claim 16 , wherein said DSL modem is a VDSL modem.
18. The device of claim 14 , wherein said disturber source is an FTTN cabinet.
19. The device of claim 14 , wherein said reference source is an FTTB cabinet in a building.
20. The device of claim 14 , wherein said downstream PSD is transmitted from said reference source by a DSL modem.