CN101145838A - A method for obtaining DWDM system optical S/N ratio - Google Patents

Abstract

The invention discloses a method of calculating optical signal noise ratio in a DWDM system, which is suitable for the DWDM system comprising an optical amplifier. The invention comprises: step 1, in accordance with the optical amplifier noise coefficient and the gain, a spontaneous radiation noise power is amplified; Step 2, the single-channel input power of the optical amplifier is calculated, and an input optical signal noise ratio is obtained in accordance with the single-channel input power and the input optical signal noise ratio; Step 3, output noise power is obtained from the amplified spontaneous radiation noise power, the input noise power, and the gain; step 4, the single-channel output power is calculated and the signal output optical signal noise ratio is obtained in accordance with the output signal power and the output signal noise power. The invention overcomes the shortcomings that the estimation method of the optical signal noise ratio is unable to adapt the non-equidistant system, span transmission optical power uneven system, lower signal noise ratio system and horizontal compatible system in the prior art.

Description

A kind of method of asking for the dwdm system Optical Signal To Noise Ratio

Technical field

The present invention relates to optical transport technology, particularly relate to a kind of method of accurately asking for DWDM (DenseWavelength Division Multiplex, dense wave division multipurpose) system's Optical Signal To Noise Ratio.

Background technology

Noise, chromatic dispersion, nonlinear effect and polarization mode dispersion are the four big key issues that present dwdm system design needs consideration.Noise mainly comes from image intensifer (OpticalAmplifier, application OA) in the dwdm system.In dwdm system design, engineering debug and equipment operation, often need to calculate or monitoring system in each network element Optical Signal To Noise Ratio (Optical Signal-to-Noise Ratio, OSNR).ITU-T(Telecommunication?Standardization?Sector?of?International

Telecommunication Union, standardization department of international telecommunication union telecommunication) G.692 (10/98) " Optical interfaces for multichannel systems with optical amplifiers ", ITU-T advise G.696.1 (07/2005) " Longitudinally compatible intra-domain DWDM in suggestion

Applications " all provided the estimation equation of Optical Signal To Noise Ratio.

ITU-T suggestion appendix G.696.1 I.1.1, supposing the system has x the section of striding, and contains 1 OBA, x-1 OLA, 1 OPA supposes the respectively section of striding loss equalization, the section of striding loss L equals the gain G of OLA _LA, the noise factor of all OA is identical, and the power output of OLA and OBA is identical, and the estimation equation that provides is:

$\mathrm{OSNR}=P_{\mathrm{out}}-L-{\mathrm{NF}}_{\mathrm{eff}}-10\·\log (x+\frac{{10}^{\frac{G_{\mathrm{BA}}}{10}}}{{10}^{\frac{L}{10}}})-10\·\log [h\·v{\·v}_r]---\left(1\right)$

The intermediate steps that the dwdm system Optical Signal To Noise Ratio is calculated need be calculated the noise power P in the 0.1nm bandwidth _n, P _n=P _ASE+ G * P _SSE, wherein, P _ASEBe the amplified spontaneous emission noise that produces by OA, P _SSEBe the source noise that is exaggerated signal, P _ASECan draw according to the noise factor of OA, the equivalent noise model of OA is referring to Fig. 1.The amplified spontaneous emission noise that OA produces $P_{\mathrm{ASE}}=(\mathrm{NF}-\frac{1}{G})\×G\×\mathrm{hvB},$ Here h is a Planck's constant, and NF is a noise factor, and v is the frequency of light signal, and B is converted to frequency bandwidth (Hz of unit) for 0.1nm noise bandwidth.At the 1550nm window, the power of hvB correspondence (dBm of unit) is about-58dBm.As a rule, have: $\mathrm{NF}>>\frac{1}{G},$ So calculating P _ASEUsually ignore shot noise in the process

But in the noise calculation of lower EDFA or DRA that gains, can not omit

Wherein, OBA (OpticalBoosting Amplifier) is a power amplifier, OLA (Optical Line Amplifier) is an optical line amplifier, OPA (Optical Fiber Amplifier) is a fiber amplifier, EDFA (Erbium-DopedFiber Amplifier) is an Erbium-Doped Fiber Amplifier, and DRA (Distributed Raman Amplifier) is a distributed raman amplifier.

In recent years along with the progress of electric territory signal processing technology, as EDC (Error Detection Code, error-detecting code) technology, FEC (Forward Error Correction, forward error correction) technology, and the various novel sign indicating number type modulation techniques that emerge in an endless stream, improved the noise tolerance of system greatly.In dwdm system, the Optical Signal To Noise Ratio minimum standard of 10Gb/s system might reach about 10dB, so more and more be necessary to consider the shared component of noise power in the gross power in the length in future.Below by signal power and the noise power size in the low Optical Signal To Noise Ratio system of representative value estimation: certain 40 ripple C-band dwdm system, suppose that the OA gain bandwidth is 35nm, the Optical Signal To Noise Ratio of signal is 15dB, and channel signal power is smooth, and single channel signal power is P1.Total signal power is that 40 * P1 total noise power is P1 * 10 so ^-15/10* (35/0.1)=11.068 * P1; The single channel noise power is P1 * 10 ^-15/10* (0.8/0.1)=0.253 * P1.Total signal power is 3.614 times of total noise power like this, and single channel signal power is 3.953 times of single channel noise power.The present invention is special in the analysis of Optical Signal To Noise Ratio with in calculating to consider noise power shared component in gross power.

In DWDM transverse compatibility system, terminal equipment may be from vendor A and C, and optical relay equipment may be from the B of manufacturer, and in this case, the Optical Signal To Noise Ratio of the signal that the needs basis transmits calculate the Optical Signal To Noise Ratio behind the optical relay.

Summary of the invention

Technical problem to be solved by this invention is to provide a kind of method of asking for the dwdm system Optical Signal To Noise Ratio, is used to overcome the shortcoming that Optical Signal To Noise Ratio evaluation method of the prior art can't be adapted to non-equidistant system, the unequal system of the section of striding transmitting optical power, low signal-to-noise ratio system and transverse compatibility system.

To achieve these goals, the invention provides a kind of method of asking for the dwdm system Optical Signal To Noise Ratio, be applicable to the dwdm system that comprises image intensifer, it is characterized in that, comprising:

Step 1 obtains amplified spontaneous emission noise power according to the noise factor of described image intensifer, gain;

Step 2 is asked for the single channel input power of described image intensifer, and obtains input noise power according to this single channel input power and input Optical Signal To Noise Ratio;

Step 3 obtains output noise power by described amplified spontaneous emission noise power, described input noise power, described gain; And

Step 4 is asked for single pass output signal power, and obtains the output Optical Signal To Noise Ratio of signal according to this output signal power and described output noise power.

The described method of asking for the dwdm system Optical Signal To Noise Ratio wherein, before described step 1, comprises that also gain, noise factor, input power, a power output of setting described image intensifer is the step of known parameters.

The described method of asking for the dwdm system Optical Signal To Noise Ratio wherein, in the described step 2, is asked for the single channel input power of described image intensifer according to single channel power output, gain, the amplified spontaneous emission noise power of described image intensifer.

The described method of asking for the dwdm system Optical Signal To Noise Ratio wherein, in the described step 2, is asked for the single channel input power of described image intensifer according to the input power of described image intensifer.

The described method of asking for the dwdm system Optical Signal To Noise Ratio wherein, in the described step 4, is asked for described single pass output signal power according to the single channel power output and the described output noise power of described image intensifer.

The described method of asking for the dwdm system Optical Signal To Noise Ratio wherein, in the described step 4, is asked for described single pass output signal power according to single pass input signal power and described gain.

The described method of asking for the dwdm system Optical Signal To Noise Ratio, wherein, the input power of described image intensifer, power output are determined by the circuit optical fiber and the system configuration of described dwdm system.

The described method of asking for the dwdm system Optical Signal To Noise Ratio, wherein, described image intensifer is Erbium-Doped Fiber Amplifier, distributed raman amplifier or semiconductor optical amplifier.

The described method of asking for the dwdm system Optical Signal To Noise Ratio, wherein, described dwdm system is C-band 40 ripple dwdm systems, C-band 80 ripple dwdm systems or C+L wave band 160 ripple dwdm systems.

The described method of asking for the dwdm system Optical Signal To Noise Ratio, wherein, described dwdm system is non-equidistant system, the unequal system of the section of striding transmitting optical power, low signal-to-noise ratio system, transverse compatibility system or Optical Add Drop Multiplexer system.

Beneficial effect of the present invention is:

Adopt the method for the invention, compare,, solved the not Optical Signal To Noise Ratio calculating of equidistant system owing to taked the method for the noise storage of all OA with art methods; Because taken into account noise power shared component in gross power, the Optical Signal To Noise Ratio that has solved the low signal-to-noise ratio system is calculated, and has improved the accuracy of Optical Signal To Noise Ratio; Because the input Optical Signal To Noise Ratio is configurable, be applicable to that also the Optical Signal To Noise Ratio of transverse compatibility system and OADM (Opticaladd/drop multiplexing, Optical Add Drop Multiplexer) system is calculated.

Describe the present invention below in conjunction with the drawings and specific embodiments, but not as a limitation of the invention.

Description of drawings

Fig. 1 is the equivalent noise model of existing OA;

Fig. 2 is the method block diagram of acquisition of the present invention system output Optical Signal To Noise Ratio;

Fig. 3 obtains the method flow diagram of single-stage OA output Optical Signal To Noise Ratio for the present invention.

Embodiment

See also shown in Figure 2ly, be the method block diagram of acquisition of the present invention system output Optical Signal To Noise Ratio.The Optical Signal To Noise Ratio of OA output signal in the present invention acquisition system step by step, the output Optical Signal To Noise Ratio of upper level OA be as the input Optical Signal To Noise Ratio of next stage OA, and consider the shared component of noise power in OA input power, the power output.OA can be based on the image intensifer of EDFA, DRA, SOA or other technologies scheme.

See also shown in Figure 3ly, obtain the method flow diagram of single-stage OA output Optical Signal To Noise Ratio for the present invention.This figure is an example with C-band 40 ripple dwdm systems, has described the method for accurate acquisition system Optical Signal To Noise Ratio.Be convenient and describe, below all parameters be linear unit.OA power is similar in the system P _{OA_total_out}=40 * P _{OA_ch_out}, P _{OA_total_in}=40 * P _{OA_ch_in}Because bandwidth chahnel is approximately 0.8nm, so the noise power in the passage is 8 times of the interior noise power of 0.1nm bandwidth.With i OA in the system is example, OA _iInput signal Optical Signal To Noise Ratio and gain, noise factor, input or output power and other relevant parameters are known conditions, according to OA _iRelevant parameter obtains OA _iThe process concrete steps of output Optical Signal To Noise Ratio as follows:

Step 301 is according to OA _iNoise factor NF _OAi, gain G _OAiObtain OA _iThe amplification radiated noise power p that produces _{OAi_ASE}, OA then _iAmplified spontaneous emission noise power P in the 0.1nm bandwidth that produces _{OAi_ASE}For:

$P_{\mathrm{OAi}\_\mathrm{ASE}}=({\mathrm{NF}}_{\mathrm{OAi}}-\frac{1}{G_{\mathrm{OAi}}})\×G_{\mathrm{OAi}}\×\mathrm{hvB}---\left(1\right)$

Situation at low gain OA can not be ignored shot noise

Step 302 is according to OA _iSingle channel power output P _{OAi_ch_out}, gain G _OAi, the amplified spontaneous emission noise power P _{OAi_ASE}Obtain OA _iSingle channel input power P _{OAi_ch_in}, perhaps according to OA _iInput power obtain OA _iSingle channel input power P _{OAi_ch_in}, OA then _iSingle channel input power P _{OAi_ch_in}For:

$P_{\mathrm{OAi}\_\mathrm{ch}\_\mathrm{in}}=\frac{P_{\mathrm{OAi}\_\mathrm{ch}\_\mathrm{out}}-8\×P_{\mathrm{OAi}\_\mathrm{ASE}}}{G_{\mathrm{OAi}}}---\left(2\right)$

Here considered total amplified spontaneous emission noise in the bandwidth chahnel, can also directly obtain the single channel input power from input power, promptly the single channel input power equals total power input divided by port number.

Step 303 is according to OA _iSingle channel input power P _{OAi_ch_in}With input Optical Signal To Noise Ratio OSNR _{OAi_in}Obtain the input noise power P _{OAi_SSE}, OA then _iThe 0.1nm bandwidth in the input noise power P _{OAi_SSE}For:

$P_{\mathrm{OAi}\_\mathrm{SSE}}=\frac{P_{\mathrm{OAi}\_\mathrm{ch}\_\mathrm{in}}}{{\mathrm{OSNR}}_{\mathrm{OAi}\_\mathrm{in}}+8}---\left(3\right)$

Here 8 * P _{OAi_SSE}Input noise power in the expression passage.

Step 304 is according to the amplified spontaneous emission noise power P _{OAi_ASE}, the input noise power P _{OAi_SSE}And OA _iGain G _OAiObtain output noise power P _{OAi_noise}, OA then _iThe 0.1nm bandwidth in output noise power P _{OAi_noise}For:

P _{OAi_noise}＝P _{OAi_SSE}×G _OAi+P _{OAi_ASE} (4)

Step 305 is according to single channel power output P _{OAi_ch_out}With output noise power P _{OAi_noise}Obtain OA _iSingle pass output signal power P _{OAi_ch_sig}, then single pass output signal power P _{OAi_ch_sig}For:

P _{OAi_ch_sig}＝P _{OAi_ch_out}-8×P _{OAi_noise}(5)

Perhaps according to single pass input signal power and gain G _OAiObtain single pass output signal power P _{OAi_ch_sig}, promptly single pass output signal power P _{OAi_ch_sig}Equal single pass input signal power and multiply by gain G _OAi

Step 306 is according to single pass output signal power P _{OAi_ch_sig}With single pass output noise power P _{OAi_noise}The output Optical Signal To Noise Ratio OSNR of picked up signal _{OAi_out}, OA then _iThe Optical Signal To Noise Ratio OSNR of output signal _{OAi_out}For:

${\mathrm{OSNR}}_{\mathrm{OAi}\_\mathrm{out}}=\frac{P_{\mathrm{OAi}\_\mathrm{ch}\_\mathrm{sig}}}{P_{\mathrm{OAi}\_\mathrm{noise}}}---\left(6\right)$

If C-band 80 ripples or C+L wave band 160 wave systems system are replaced by 4 with the above-mentioned k factor 8 and are got final product.If more intensive or more sparse dwdm system is revised the corresponding k factor according to the bandwidth chahnel of system.

The method that accurately obtains the dwdm system Optical Signal To Noise Ratio can be used as software function module and is embedded on the webmaster of dwdm system, thus the Optical Signal To Noise Ratio of MPI-S, MPI-R, S ', R ' each point in the acquisition system.The actual engineering system of DWDM generally can not put wavelength channel by full configuration, so need be according to the component of actual conditions calculating noise power in gross power.The monitoring function module of each network element can be monitored input power and the power output of the OA of this network element in the dwdm system; And know the input Optical Signal To Noise Ratio of OA at the corresponding levels from the output Optical Signal To Noise Ratio of higher level OA; The user imports parameters such as the noise factor, gain, system channel number of OA; Obtain the output Optical Signal To Noise Ratio of OA in this network element according to above-mentioned parameter.The initial light signal to noise ratio of system can be imported as 50dB or other desired values; If the transverse compatibility system, should import the Optical Signal To Noise Ratio of the signal that opposite equip. transmits.

The method that accurately obtains the dwdm system Optical Signal To Noise Ratio also can be applicable in the dwdm system design, and as the configuration design of assistant software guidance system, the input power of OA and power output are by circuit optical fiber loss and system configuration decision in the system.

The method of a kind of accurate acquisition dwdm system Optical Signal To Noise Ratio that the present invention proposes is adapted to non-equidistant system, the unequal system of the section of striding transmitting optical power, low signal-to-noise ratio system and transverse compatibility system.

Certainly; the present invention also can have other various embodiments; under the situation that does not deviate from spirit of the present invention and essence thereof; those of ordinary skill in the art work as can make various corresponding changes and distortion according to the present invention, but these corresponding changes and distortion all should belong to the protection range of the appended claim of the present invention.

Claims (10)

1. a method of asking for the dwdm system Optical Signal To Noise Ratio is applicable to the dwdm system that comprises image intensifer, it is characterized in that, comprising:

Step 1 obtains amplified spontaneous emission noise power according to the noise factor of described image intensifer, gain;

Step 2 is asked for the single channel input power of described image intensifer, and obtains input noise power according to this single channel input power and input Optical Signal To Noise Ratio;

Step 3 obtains output noise power by described amplified spontaneous emission noise power, described input noise power, described gain; And

Step 4 is asked for single pass output signal power, and obtains the output Optical Signal To Noise Ratio of signal according to this output signal power and described output noise power.

2. the method for asking for the dwdm system Optical Signal To Noise Ratio according to claim 1 is characterized in that, before described step 1, comprises that also gain, noise factor, input power, a power output of setting described image intensifer is the step of known parameters.

3. the method for asking for the dwdm system Optical Signal To Noise Ratio according to claim 2, it is characterized in that, in the described step 2, ask for the single channel input power of described image intensifer according to single channel power output, gain, the amplified spontaneous emission noise power of described image intensifer.

4. according to claim 2 or the 3 described methods of asking for the dwdm system Optical Signal To Noise Ratio, it is characterized in that, in the described step 2, ask for the single channel input power of described image intensifer according to the input power of described image intensifer.

5. according to claim 2 or the 3 described methods of asking for the dwdm system Optical Signal To Noise Ratio, it is characterized in that, in the described step 4, ask for described single pass output signal power according to the single channel power output and the described output noise power of described image intensifer.

6. according to claim 2 or the 3 described methods of asking for the dwdm system Optical Signal To Noise Ratio, it is characterized in that, in the described step 4, ask for described single pass output signal power according to single pass input signal power and described gain.

7. according to claim 2 or the 3 described methods of asking for the dwdm system Optical Signal To Noise Ratio, it is characterized in that the input power of described image intensifer, power output are determined by the circuit optical fiber and the system configuration of described dwdm system.

8. according to claim 1, the 2 or 3 described methods of asking for the dwdm system Optical Signal To Noise Ratio, it is characterized in that described image intensifer is Erbium-Doped Fiber Amplifier, distributed raman amplifier or semiconductor optical amplifier.

9. according to claim 1, the 2 or 3 described methods of asking for the dwdm system Optical Signal To Noise Ratio, it is characterized in that described dwdm system is C-band 40 ripple dwdm systems, C-band 80 ripple dwdm systems or C+L wave band 160 ripple dwdm systems.

10. according to claim 1, the 2 or 3 described methods of asking for the dwdm system Optical Signal To Noise Ratio, it is characterized in that described dwdm system is non-equidistant system, the unequal system of the section of striding transmitting optical power, low signal-to-noise ratio system, transverse compatibility system or Optical Add Drop Multiplexer system.

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