Method and Apparatus for Equalizing Link Performance

• US 20140314405A1
• Filed: 06/27/2014
• Published: 10/23/2014
• Est. Priority Date: 12/28/2011
• Status: Active Grant

• Current Assignee: Huawei Technologies Co., Ltd. (Huawei Investment & Holding Co., Ltd.)
• Original Assignee: Huawei Technologies Co., Ltd. (Huawei Investment & Holding Co., Ltd.)
• Inventors: Zhang, Sen, Feng, Zhiyong, Han, Jianrui
• Granted Patent: US 9,172,475 B2
• Time in Patent Office: Days
• US Class Current: 398/26
• CPC Class Codes: H04B 10/07953 Monitoring or measuring OSNR, BER or Q
• CPC Class Codes: H04B 10/07955 Monitoring or measuring power
• CPC Class Codes: H04B 10/2931 using AGC H04B10/294 takes precedence
• CPC Class Codes: H04B 10/2935 with a cascade of amplifiers
• CPC Class Codes: H04B 10/294 in a multiwavelength system, e.g. gain equalisation
• CPC Class Codes: H04B 10/564 Power control
• CPC Class Codes: H04J 14/0221 Power control, e.g. to keep the total optical power constant
• CPC Class Codes: H04J 14/0261 at the optical multiplex section layer
• CPC Class Codes: H04Q 2213/1301 Optical transmission, optical switches
• CPC Class Codes: H04Q 2213/1308 Power supply

Abstract

Embodiments of the present invention provide a method and an apparatus for equalizing link performance, and relate to the field of optical wavelength division multiplexing. In the present invention, target input power spectra and target output power spectra in all OMS sections in a network and single wave attenuation at a power adjusting point may be concurrently calculated based on link information of the OMS sections, fast adjustment may also be implemented for a complex network topology, and the adjustment may be implemented in a one-off manner to avoid a problem that iteration adjustment is caused by mutual impact of power adjusting points during serial adjustment in a ring network. In addition, it is not required to connect an optical path in the calculation phase, thereby eliminating reliance on a connected optical path in a process for equalizing link performance.

Claims

1. A method for equalizing link performance, the method comprising:

obtaining link information of any optical multiplexing section in an optical wavelength division multiplexing system, and calculating an input power of each wavelength of each optical amplifier in the any optical multiplexing section according to the link information of the any optical multiplexing section;

calculating an optical signal to noise ratio degradation amount of each wavelength according to the input power of each wavelength of each optical amplifier in the any optical multiplexing section;

when a difference between optical signal to noise ratio degradation amounts of wavelengths is within a preset threshold range, calculating an output power of each wavelength of a last optical amplifier in the any optical multiplexing section, and when a difference between output power of wavelengths in the last optical amplifier of the any optical multiplexing section is within a preset threshold range, using the input power of each wavelength of a first optical amplifier and the output power of each wavelength of the last optical amplifier in the any optical multiplexing section as a target input power and a target output power in the any optical multiplexing section;

calculating target input power and target output power of each wavelength in a next optical multiplexing section of the any optical multiplexing section by using a same method for calculating the target input power and the target output power of each wavelength in the any optical multiplexing section; and

determining single wave attenuation of each wavelength caused by a power adjusting point between the any optical multiplexing section and the next optical multiplexing section according to the target output power of each wavelength in the any optical multiplexing section and the target input power of each wavelength in the next optical multiplexing section.

2. The method according to claim 1, wherein the link information comprises wavelength distribution, link loss, a type of the optical amplifier, and a gain of each wavelength caused by the optical amplifier, and wherein the calculating input power of each wavelength of each optical amplifier in the any optical multiplexing section according to the link information of the any optical multiplexing section further comprises:

determining typical input optical power of the first optical amplifier according to a type of the first optical amplifier in the any optical multiplexing section, average gain of wavelengths caused by the first optical amplifier, and a number of full wavelengths in the optical wavelength division multiplexing system, and using the typical input optical power of the first optical amplifier as input power of the first optical amplifier, wherein the average gain of the wavelengths caused by the first optical amplifier is obtained by averaging a sum of the gains of the wavelengths caused by the first optical amplifier;

calculating output power of each wavelength of the first optical amplifier according to the input power of the first optical amplifier and the gain of each wavelength caused by the first optical amplifier, and calculating input power of each wavelength of a second optical amplifier according to a formula P_inF<sup>λ

k</sup>−

L_F-X=P_inX<sup>λ

k</sup>, wherein P_inF<sup>λ

k</sup> indicates output power of each wavelength λ

_k in a previous optical amplifier F, L_F-X indicates link loss of a wavelength between the previous optical amplifier F and a next optical amplifier X, and P_inX<sup>λ

k</sup> indicates input power of each wavelength λ

_k in the next optical amplifier X; and

calculating input power of each wavelength of each optical amplifier in the any optical multiplexing section by using a same method for calculating the input power of each wavelength of the second optical amplifier.

3. The method according to claim 1, wherein the calculating an optical signal to noise ratio degradation amount of each wavelength according to the input power of each wavelength of each optical amplifier in the any optical multiplexing section further comprises calculating the optical signal to noise ratio degradation amount of each wavelength according to the following formula:

4. The method according to claim 1, wherein the calculating output power of each wavelength of a last optical amplifier in the any optical multiplexing section further comprises calculating output power of each wavelength of the last optical amplifier according to the input power of each wavelength of the last optical amplifier in the any optical multiplexing section and a gain of each wavelength caused by the last optical amplifier.

5. The method according to claim 1, wherein the determining single wave attenuation of each wavelength caused by a power adjusting point between the any optical multiplexing section and the next optical multiplexing section according to the target output power of each wavelength in the any optical multiplexing section and the target input power of each wavelength in the next optical multiplexing section further comprises using a difference between the target output power of each wavelength in the any optical multiplexing section and the target input power of each wavelength in the next optical multiplexing section as the single wave attenuation of each wavelength caused by the power adjusting point.

6. The method according to claim 1, wherein when the difference between the optical signal to noise ratio degradation amounts of the wavelengths is not within a preset threshold range, or when the difference between the output power of the wavelengths of the last optical amplifier in the any optical multiplexing section is not within a preset threshold range, the method further comprises redefining the input power of each wavelength of each optical amplifier in the any optical multiplexing section, and recalculating, according to the redefined input power of each wavelength of each optical amplifier in the any optical multiplexing section, the optical signal to noise ratio degradation amount of each wavelength.

7. An apparatus for equalizing link performance, comprising:

an input power calculating module configured to obtain link information of any optical multiplexing section in an optical wavelength division multiplexing system, and calculate input power of each wavelength of each optical amplifier in the any optical multiplexing section according to the link information of the any optical multiplexing section;

an optical signal to noise ratio degradation amount calculating module configured to calculate an optical signal to noise ratio degradation amount of each wavelength according to the input power of each wavelength of each optical amplifier in the any optical multiplexing section;

a target power calculating module, configured to, when a difference between the optical signal to noise ratio degradation amounts of wavelengths is within a preset threshold range, calculate output power of each wavelength of a last optical amplifier in the any optical multiplexing section, and when a difference between the output power of wavelengths in the last optical amplifier of the any optical multiplexing section is within a preset threshold range, use the input power of each wavelength of a first optical amplifier and the output power of each wavelength of the last optical amplifier in the any optical multiplexing section as a target input power and a target output power in the any optical multiplexing section, wherein the target power calculating module is further configured to calculate target input power and target output power of each wavelength in a next optical multiplexing section of the any optical multiplexing section by using a same method for calculating the target input power and the target output power of each wavelength in the any optical multiplexing section; and

a single wave attenuation module, configured to determine single wave attenuation of each wavelength caused by a power adjusting point between the any optical multiplexing section and the next optical multiplexing section according to the target output power of each wavelength in the any optical multiplexing section and the target input power of each wavelength in the next optical multiplexing section.

8. The apparatus according to claim 7, wherein the link information comprises wavelength distribution, link loss, a type of the optical amplifier, and a gain of each wavelength caused by the optical amplifier and wherein the input power calculating module comprises an obtaining unit and a calculating unit, wherein the obtaining unit is configured to obtain the link information of the any optical multiplexing section in the optical wavelength division multiplexing system, and wherein the calculating unit is configured to:

determine a typical input optical power of a first optical amplifier according to a type of the first optical amplifier in the any optical multiplexing section, an average gain of wavelengths caused by the first optical amplifier, and a number of full wavelengths in the optical wavelength division multiplexing system, and use the typical input optical power of the first optical amplifier as an input power of the first optical amplifier, wherein the average gain of the wavelengths caused by the first optical amplifier is obtained by averaging a sum of the gains of the wavelengths caused by the first optical amplifier;

calculate output power of each wavelength of the first optical amplifier according to the input power of the first optical amplifier and the gain of each wavelength caused by the first optical amplifier; and

calculate the input power of each wavelength of a second optical amplifier according to the following formula;

P_inF<sup>λ

k</sup>−

L_F-X=P_inX<sup>λ

k</sup>

wherein P_inF<sup>λ

k</sup> indicates output power of a wavelength λ

_k in a previous optical amplifier F, L_F-X indicates link loss of a wavelength between the previous optical amplifier F and a next optical amplifier X, and P_inX<sup>λ

k</sup> indicates input power of the wavelength λ

_k in the next optical amplifier X;

and calculate input power of each wavelength of each optical amplifier in the any optical multiplexing section by using a same method for calculating the input power of each wavelength of the second optical amplifier.

9. The apparatus according to claim 7, wherein the optical signal to noise ratio degradation amount calculating module is specifically configured to calculate the optical signal to noise ratio degradation amount of each wavelength according to the following formula:

10. The apparatus according to claim 7, wherein the target power calculating module, when calculating output power of each wavelength of a last optical amplifier in the any optical multiplexing section, is further configured to calculate output power of each wavelength of the last optical amplifier according to the input power of each wavelength of the last optical amplifier in the any optical multiplexing section and a gain of each wavelength caused by the last optical amplifier.

11. The apparatus according to claim 7, wherein the single wave attenuation module is further configured to use a difference between the target output power of each wavelength in the any optical multiplexing section and the target input power of each wavelength in the next optical multiplexing section as the single wave attenuation of each wavelength caused by the power adjusting point.

12. The apparatus according to claim 7, wherein the optical signal to noise ratio degradation amount calculating module is further configured to, when the difference between the optical signal to noise ratio degradation amounts of the wavelengths is not within a preset threshold range or when the difference between the output power of the wavelengths of the last optical amplifier in the any optical multiplexing section is not within a preset threshold range, redefine the input power of each wavelength of each optical amplifier in the any optical multiplexing section, and recalculate, according to the redefined input power of each wavelength of each optical amplifier in the any optical multiplexing section, the optical signal to noise ratio degradation amount of each wavelength.