Preemphasis of an optical wavelength multiplex signal
View Patent ↗Methods are described for preemphasizing an optical multiplex signal that comprises a plurality of signals having different wavelengths, which are transmitted by a transmitter to a receiver. Power levels for the signals are set at the transmitter and measured at the receiver. A mean power level for the transmit-side signals is ascertained. New signal power level values are ascertained from the current power levels of the signals at the transmitter and at the receiver and set on the transmit side such that signal-to-noise ratios for all signal are approximately equalized at the receiver. In order to make more precise settings for the preemphasis, mean gain values and mean attenuations are ascertained from the sum power levels for the multiplex signal measured at the input and at the output of each amplification section and incorporated together with an effective noise figure into the process of ascertaining the new signal power level values. The preemphasis is thus performed autonomously without there being any need for further planning resources for control purposes.
1. A method for preemphasizing an optical multiplex signal that comprises a plurality of signals having different wavelengths, transmitted by a transmitter by way of a plurality of substantially identical amplification sections to a receiver, comprising:
determining on the transmitter a mean power level ( P_Tx(λ) Beginn ) and an optical power level spectrum (P_Tx(λ) Beginn ) for the optical multiplex signal;
determining on the receiver an optical power level spectrum (P_Rx(λ) Beginn ) for the optical multiplex signal;
determining the sum power levels for the multiplex signal at the input to and output from each amplification section, and determining mean gain values ( G i (λ) ) and mean attenuations ( a i (λ) ) for each amplification section from the measured values for the sum power levels of the multiplex signal;
calculating a gain function (G link (λ)) which characterizes an overall gain of a transmission path from a relationship between optical power level spectra (P_Tx(λ) Beginn , P_Rx(λ) Beginn ) determined on the transmitter and the receiver;
using the values G i (λ) and a i (λ) , calculating a wavelength-dependent function (Q(λ)) according to the specification
Q
(
λ
)
=
∑
i
=
0
N
G
link
-
i
/
(
N
+
1
)
(
λ
)
·
〈
G
i
(
λ
)
〉
·
∏
j
=
i
+
1
N
〈
G
j
(
λ
)
〉
·
〈
a
j
(
λ
)
〉
which serves to correct a new signal power level values (P_Tx(λ)) to be set on the transmitter, where j represents an auxiliary variable; and
using the correction function Q(λ) and an effective noise figure (F eff (λ)), calculating the new signal power level values (P_Tx(λ)) to be set on the transmitter according to a formula
P_Tx
(
λ
)
=
Q
(
λ
)
·
F
eff
(
λ
)
〈
Q
(
λ
)
·
F
eff
(
λ
)
〉
·
〈
P_Tx
(
λ
)
Beginn
〉
so that signal-to-noise ratios for signals of the multiplex signal can be matched to one another at the receiver, wherein angle brackets represent a mean value for a value entered within them.
2. A method for preemphasizing an optical multiplex signal comprising a plurality of signals having different wavelengths, transmitted by a transmitter by way of a plurality of different amplification sections to a receiver, comprising:
ascertaining on transmitter a mean power level ( P_Tx(λ) Beginn ) and an optical power level spectrum (P_Tx(λ) Beginn ) for the optical multiplex signal;
ascertaining on the receiver an optical power level spectrum (P_Rx(λ) Beginn ) for the optical multiplex signal;
ascertaining the sum power levels for the multiplex signal at the input to and output from each amplification section, and ascertaining mean gain values ( G i (λ) ) and mean attenuations ( a i (λ) ) for each amplification section from measured values for the sum power levels of the multiplex signal;
calculating a gain function (G link (λ)) which characterizes an overall gain of a transmission path from a relationship between optical power level spectra (P_Tx(λ) Beginn , P_Rx(λ) Beginn ) ascertained on the transmitter and the receiver;
ascertaining a relative code number (k i ) which characterizes a difference between the gain value (G i (λ)) and the mean value ( G i (λ) ) for each amplification section i for each optical amplifier;
calculating, using the relative code numbers (k i ), a wavelength-dependent function (Q(λ)) according to a specification
Q
(
λ
)
=
∑
i
=
0
N
G
link
(
λ
)
-
(
∑
j
=
0
i
-
1
k
j
)
/
(
∑
j
=
0
N
k
j
)
·
〈
G
i
(
λ
)
〉
·
∏
j
=
i
+
1
N
〈
G
j
(
λ
)
〉
·
〈
a
j
(
λ
)
〉
which serves to correct a new signal power level values (P_Tx(λ)) to be set on the transmitter, and wherein j represents an auxiliary variable; and
calculating, using the correction function Q(λ) and an effective noise figure (F eff (λ)), the new signal power level values (P_Tx(λ)) to be set on the transmitter according to a formula
P_Tx
(
λ
)
=
Q
(
λ
)
·
F
eff
(
λ
)
〈
Q
(
λ
)
·
F
eff
(
λ
)
〉
·
〈
P_Tx
(
λ
)
Beginn
〉
so that signal-to-noise ratios for signals of the multiplex signal can be matched to one another at the receiver, wherein angle brackets represent a mean value for a value entered within them.
3. A method for preemphasizing an optical multiplex signal that comprises a plurality of signals having different wavelengths, are transmitted by a transmitter by way of a plurality of different amplification sections having amplifiers with known gain factors G i (λ)=g i typ (λ)· G o (λ) , ∀i=1,2, . . . , N to a receiver, comprising:
ascertaining on the transmitter a mean power level ( P_Tx(λ) Beginn ) and an optical power level spectrum (P_Tx(λ) Beginn ) for the optical multiplex signal;
ascertaining on the receiver an optical power level spectrum (P_Rx(λ) Beginn ) for the optical multiplex signal;
ascertaining sum power levels for the multiplex signal at the input to and output from each amplification section, and ascertaining mean gain values ( G i (λ) ) and mean attenuations ( a i (λ) ) for each amplification section from measured values for the sum power levels of the multiplex signal;
calculating an overall gain (G ges (λ)) between the transmitter and the receiver according an equation
G
ges
(
λ
)
=
〈
G
0
(
λ
)
〉
·
[
∏
j
=
1
N
〈
G
j
(
λ
)
〉
·
〈
a
j
(
λ
)
〉
]
·
∏
i
=
0
N
(
g
i
typ
)
m
i
wherein (M i ) is chosen as an exponent of gain factors (g j typ (λ)) such that characteristic differences between an overall gain (G ges (λ)) and the measured gain (G link (λ)) are minimized and wherein G o (λ) is the mean gain of a first amplifier on the transmitter;
calculating a wavelength-dependent function (Q(λ)) according to a specification
Q
(
λ
)
=
∑
i
=
0
N
〈
G
i
(
λ
)
〉
·
[
∏
j
=
i
+
1
N
〈
G
j
(
λ
)
〉
·
〈
a
j
(
λ
)
〉
]
·
∏
j
=
i
N
(
g
j
typ
)
m
j
∏
i
=
0
N
(
g
i
typ
)
m
i
,
which serves to correct a new signal power level values (P_Tx(λ)) to be set on the transmitter, and where j represents an auxiliary variable; and
calculating, using the correction function Q(λ) and an effective noise figure (F eff (λ)), the new signal power level values (P_Tx(λ)) to be set on the transmitter according to a formula
P_Tx
(
λ
)
=
Q
(
λ
)
·
F
eff
(
λ
)
〈
Q
(
λ
)
·
F
eff
(
λ
)
〉
·
〈
P_Tx
(
λ
)
Beginn
〉
so that signal-to-noise ratios for signals of the multiplex signal can be matched to one another at the receiver, wherein angle brackets represent a mean value for a value entered within them.
4. A method for preemphasizing an optical multiplex signal comprising a plurality of signals having different wavelengths, transmitted by a transmitter by way of a plurality of amplification sections to a receiver, and a partial transmission function g(λ) k:m is known for a group of 1<m−k+1<N of N amplification sections, comprising:
ascertaining on transmitter a mean power level ( P_Tx(λ) Beginn ) and an optical power level spectrum (P_Tx(λ) Beginn ) for the optical multiplex signal;
ascertaining on the receiver an optical power level spectrum (P_Rx(λ) Beginn ) for the optical multiplex signal;
ascertaining sum power levels for the multiplex signal at the input to and output from each amplification section and mean gain values ( G i (λ) ), and ascertaining mean attenuations ( a i (λ) ) for each amplification section from measured values for the sum power levels of the multiplex signal;
defining a partial transmission function
g
(
λ
)
k
:
m
=
∏
j
=
k
m
G
j
(
λ
)
·
a
j
(
λ
)
for the group of 1<m−k+1<N of N amplification sections such that gain or form factors g j (λ) of a gain profile are identical for all amplification sections jε[k:m] of a partial path and are calculated in accordance with
g(λ) j =g(λ) k:m 1/(m−k+1)
where j, k and m are auxiliary variables;
calculating a wavelength-dependent function (Q(λ)), taking G j (λ)=g(λ) j · G j (λ) ∀jε[k:m] into consideration, according to a specification
Q
(
λ
)
=
∑
i
=
0
N
∏
l
=
0
i
G
l
-
1
(
λ
)
·
〈
G
i
(
λ
)
〉
·
∏
j
=
i
+
1
N
〈
G
j
(
λ
)
〉
·
〈
a
j
(
λ
)
〉
,
which serves to correct a new signal power level values (P_Tx(λ)) to be set on the transmitter, and where l represents an auxiliary variable; and
calculating, using the correction function Q(λ) and an effective noise figure (F eff (λ)), the new signal power level values (P_Tx(λ)) to be set on the transmitter according to a formula
P_Tx
(
λ
)
=
Q
(
λ
)
·
F
eff
(
λ
)
〈
Q
(
λ
)
·
F
eff
(
λ
)
〉
·
〈
P_Tx
(
λ
)
Beginn
〉
so that signal-to-noise ratios for signals of the multiplex signal can be matched to one another at the receiver, wherein angle brackets represent a mean value for a value entered within them.
5. A computer-readable medium storing a program for preemphasizing an optical multiplex signal that comprises a plurality of signals having different wavelengths, transmitted by a transmitter by way of a plurality of substantially identical amplification sections to a receiver, the program executable by a computer, comprising:
determining on the transmitter a mean power level ( P_Tx(λ) Beginn ) and an optical power level spectrum (P_Tx(λ) Beginn ) for the optical multiplex signal;
determining on the receiver an optical power level spectrum (P_Rx(λ) Beginn ) for the optical multiplex signal;
determining the sum power levels for the multiplex signal at the input to and output from each amplification section, and determining mean gain values ( G i (λ) ) and mean attenuations ( a i (λ) ) for each amplification section from the measured values for the sum power levels of the multiplex signal;
calculating a gain function (G link (λ)) which characterizes an overall gain of a transmission path from a relationship between optical power level spectra (P_Tx(λ) Beginn , P_Rx(λ) Beginn ) determined on the transmitter and the receiver;
using the values G i (λ) and a i (λ) , calculating a wavelength-dependent function (Q(λ)) according to the specification
Q
(
λ
)
=
∑
i
=
0
N
G
link
-
i
/
(
N
+
1
)
(
λ
)
·
〈
G
i
(
λ
)
〉
·
∏
j
=
i
+
1
N
〈
G
j
(
λ
)
〉
·
〈
a
j
(
λ
)
〉
which serves to correct a new signal power level values (P_Tx(λ)) to be set on the transmitter, where j represents an auxiliary variable; and
using the correction function Q(λ) and an effective noise figure (F eff (λ)), calculating the new signal power level values (P_Tx(λ)) to be set on the transmitter according to a formula
P_Tx
(
λ
)
=
Q
(
λ
)
·
F
eff
(
λ
)
〈
Q
(
λ
)
·
F
eff
(
λ
)
〉
·
〈
P_Tx
(
λ
)
Beginn
〉
so that signal-to-noise ratios for signals of the multiplex signal can be matched to one another at the receiver, wherein angle brackets represent a mean value for a value entered within them.
6. The method according claim 5 , wherein the control module comprises at least one local control unit at each amplification section.
7. The method according claim 5 , wherein the control module is part of a network management system.
8. A computer-readable medium storing a program for preemphasizing an optical multiplex signal comprising a plurality of signals having different wavelengths, transmitted by a transmitter by way of a plurality of different amplification sections to a receiver, the program executable by a computer, comprising:
ascertaining on the transmitter a mean power level ( P_Tx(λ) Beginn ) and an optical power level spectrum (P_Tx(λ) Beginn ) for the optical multiplex signal;
ascertaining on the receiver an optical power level spectrum (P_Rx(λ) Beginn ) for the optical multiplex signal;
ascertaining the sum power levels for the multiplex signal at the input to and output from each amplification section, and ascertaining mean gain values ( G i (λ) ) and mean attenuations ( a i (λ) ) for each amplification section from measured values for the sum power levels of the multiplex signal;
calculating a gain function (G link (λ)) which characterizes an overall gain of a transmission path from a relationship between optical power level spectra (P_Tx(λ) Beginn , P_Rx(λ) Beginn ) ascertained on the transmitter and the receiver;
ascertaining a relative code number (K i ) which characterizes a difference between the gain value (G i (λ)) and the mean value ( G i (λ) ) for each amplification section i for each optical amplifier;
calculating, using the relative code numbers (K i ), a wavelength-dependent function (Q(λ)) according to a specification
Q
(
λ
)
=
∑
i
=
0
N
G
link
(
λ
)
-
(
∑
j
=
0
i
-
1
k
j
)
/
(
∑
j
=
0
N
k
j
)
·
〈
G
i
(
λ
)
〉
·
∏
j
=
i
+
1
N
〈
G
j
(
λ
)
〉
·
〈
a
j
(
λ
)
〉
which serves to correct a new signal power level values (P_Tx(λ)) to be set on transmitter, and wherein j represents an auxiliary variable; and
calculating, using the correction function Q(λ) and an effective noise figure ( F eff (λ)), the new signal power level values (P_Tx(λ)) to be set on the transmitter according to a formula
P_Tx
(
λ
)
=
Q
(
λ
)
·
F
eff
(
λ
)
〈
Q
(
λ
)
·
F
eff
(
λ
)
〉
·
〈
P_Tx
(
λ
)
Beginn
〉
so that signal-to-noise ratios for signals of the multiplex signal can be matched to one another at the receiver, wherein angle brackets represent a mean value for a value entered within them.
9. The method according claim 8 , wherein the control module comprises at least one local control unit at each amplification section.
10. The method according claim 8 , wherein the control module is part of a network management system.
11. A computer-readable medium storing a program for preemphasizing an optical multiplex signal that comprises a plurality of signals having different wavelengths, are transmitted by a transmitter by way of a plurality of different amplification sections having amplifiers with known gain factors G i (λ)=g i typ (λ)· G 0 (λ) , ∀i=1, 2, . . . , N to a receiver, the program executable by a computer, comprising:
ascertaining on the transmitter a mean power level ( P_Tx(λ) Beginn ) and an optical power level spectrum (P_Tx(λ) Beginn ) for the optical multiplex signal;
ascertaining on the receiver an optical power level spectrum (P_Rx(λ) Beginn ) for the optical multiplex signal;
ascertaining sum power levels for the multiplex signal at the input to and output from each amplification section, and ascertaining mean gain values ( G i (λ) ) and mean attenuations ( a i (λ) ) for each amplification section from measured values for the sum power levels of the multiplex signal;
calculating an overall gain (G ges (λ)) between the transmitter and the receiver according an equation
G
ges
(
λ
)
=
〈
G
0
(
λ
)
〉
·
[
∏
j
=
1
N
〈
G
j
(
λ
)
〉
·
〈
a
j
(
λ
)
〉
]
·
∏
i
=
0
N
(
g
i
typ
)
m
i
wherein (m i ) is chosen as an exponent of gain factors (g j typ (λ)) such that characteristic differences between an overall gain (G ges (λ)) and the measured gain (G link (λ)) are minimized and wherein G o (λ) is the mean gain of a first amplifier on the transmitter;
calculating a wavelength-dependent function (Q(λ)) according to a specification
Q
(
λ
)
=
∑
i
=
0
N
〈
G
i
(
λ
)
〉
·
[
∏
j
=
i
+
1
N
〈
G
j
(
λ
)
〉
·
〈
a
j
(
λ
)
〉
]
·
∏
j
=
i
N
(
g
j
typ
)
m
j
∏
i
=
0
N
(
g
i
typ
)
m
i
,
which serves to correct a new signal power level values (P_Tx(λ)) to be set on the transmitter, and where j represents an auxiliary variable; and
calculating, using the correction function Q(λ) and an effective noise figure (F eff (λ)), the new signal power level values (P_Tx(λ)) to be set on the transmitter according to a formula
P_Tx
(
λ
)
=
Q
(
λ
)
·
F
eff
(
λ
)
〈
Q
(
λ
)
·
F
eff
(
λ
)
〉
·
〈
P_Tx
(
λ
)
Beginn
〉
so that signal-to-noise ratios for signals of the multiplex signal can be matched to one another at the receiver, wherein angle brackets represent a mean value for a value entered within them.
12. The method according claim 11 , wherein the control module comprises at least one local control unit at each amplification section.
13. The method according claim 11 , wherein the control module is part of a network management system.
14. A computer-readable medium storing a program for preemphasizing an optical multiplex signal comprising a plurality of signals having different wavelengths, transmitted by a transmitter by way of a plurality of amplification sections to a receiver, and a partial transmission function g(λ) k:m is known for a group of 1<m−k+1<N of N amplification sections, the program executable by a computer, comprising:
ascertaining on the transmitter a mean power level ( P_Tx(λ) Beginn ) and an optical power level spectrum (P_Tx(λ) Beginn ) for the optical multiplex signal;
ascertaining on the receiver an optical power level spectrum (P_Rx(λ) Beginn ) for the optical multiplex signal;
ascertaining sum power levels for the multiplex signal at the input to and output from each amplification section and mean gain values ( G i (λ) ), and ascertaining mean attenuations ( a i (λ) )for each amplification section from measured values for the sum power levels of the multiplex signal;
defining a partial transmission function
g
(
λ
)
k
:
m
=
∏
j
=
k
m
G
j
(
λ
)
·
a
j
(
λ
)
for the group of 1<m−k+1<N of N amplification sections such that gain or form factors g j (λ) of a gain profile are identical for all amplification sections jε[k:m] of a partial path and are calculated in accordance with
g(λ) j =g(λ) k:m 1/(m−k=1)
where j, k and m are auxiliary variables;
calculating a wavelength-dependent function (Q(λ)), taking G j (λ)=g(λ) j · G j (λ) ∀jε[k:m] into consideration, according to a specification
Q
(
λ
)
=
∑
i
=
0
N
∏
l
=
0
i
G
l
-
1
(
λ
)
·
〈
G
i
(
λ
)
〉
·
∏
j
=
i
+
1
N
〈
G
j
(
λ
)
〉
·
〈
a
j
(
λ
)
〉
,
which serves to correct a new signal power level values (P_Tx(λ)) to be set on the transmitter, and where l represents an auxiliary variable; and
calculating, using the correction function Q(λ) and an effective noise figure (F eff (λ)), the new signal power level values (P_Tx(λ)) to be set on the transmitter according to a formula
P_Tx
(
λ
)
=
Q
(
λ
)
·
F
eff
(
λ
)
〈
Q
(
λ
)
·
F
eff
(
λ
)
〉
·
〈
P_Tx
(
λ
)
Beginn
〉
so that signal-to-noise ratios for signals of the multiplex signal can be matched to one another at the receiver, wherein angle brackets represent a mean value for a value entered within them.
15. The method according claim 14 , wherein the control module comprises at least one local control unit at each amplification section.
16. The method according claim 14 , wherein the control module is part of a network management system.