Optical error simulation system

• US 20030115028A1
• Filed: 10/10/2002
• Published: 06/19/2003
• Est. Priority Date: 10/10/2001
• Status: Active Grant

• Current Assignee: Astoria Consultancy Limited
• Original Assignee: Vpisystems Pty., Ltd.
• Inventors: Summerfield, Mark Adam John, Kuzmin, Konstantin
• Granted Patent: US 7,233,962 B2
• Time in Patent Office: Days
• US Class Current: 703/6
• CPC Class Codes: H04B 10/07 Arrangements for monitoring or testing transmission systems; Arrangements for fault measurement of transmission systems

Abstract

A method for estimating a measure of the quality of the received signal in a computer simulation of an optical transmission system, wherein the simulation includes additive optical noise generated by components within the transmission system. One or more sets of parameters of a first non-gaussian probability density function are calculated so as to approximate a suitable fit to the amplitude distribution of the received signal, including the effects of deterministic processing in the receiver but excluding the effects of statistical noise fluctuations introduced by the receiver. One or more sets of parameters of a second non-gaussian probability density function are then calculated so as to approximate a suitable fit to the amplitude distribution of the received signal, including the effects of deterministic processing and statistical noise fluctuations in the received signal using the calculated set(s) of parameters of the first non-gaussian probability density function and pre-specified statistical properties of the noise fluctuations introduced by the receiver. The measure of quality may then be computed using the set(s) of parameters of the second non-gaussian probability density function.

Claims

1. A method for estimating a measure of the quality of a received signal in a computer simulation of an optical transmission system, wherein the simulation includes additive optical noise generated by components within the transmission system, the method including the steps of:

a) calculating one or more sets of parameters of a first non-gaussian probability density function so as to approximate a suitable fit to the amplitude distribution of the received signal, including the effects of deterministic processing in the receiver but excluding the effects of statistical noise fluctuations introduced by the receiver;

b) calculating one or more sets of parameters of a second non-gaussian probability density function that approximates a suitable fit to the amplitude distribution of the received signal, including the effects of deterministic processing and statistical noise fluctuations in the received signal using the calculated set(s) of parameters of the first non-gaussian probability density function and pre-specified statistical properties of the noise fluctuations introduced by the receiver; and

c) computing the measure of quality using the set(s) of parameters of the second non-gaussian probability density function.

2. The method of claim 1 wherein said components of the transmission system include optical amplifiers.

3. The method of claim 2 wherein said optical amplifiers comprise erbium-doped fiber amplifiers.

4. The method of claim 1 wherein said statistical properties of the noise introduced by the receiver comprise a gaussian distribution characterized by its mean and variance.

5. The method of claim 1 wherein said first non-gaussian probability density function comprises a non-central chi square (x²) probability density function.

6. The method of claim 1 wherein said received signal comprises an intensity-modulated digital signal.

7. The method of claim 6 wherein said measure of the quality of the received signal comprises the bit-error-rate.

8. The method of claim 7 wherein at least two sets of parameters for each of said first and second non-gaussian probability density functions are calculated, corresponding respectively to the amplitude distributions of received data ‘

ones’ and

received data ‘

zeros’

.

9. The method of claim 1 wherein said received signal is passed through a narrow optical filter prior to reception.

10. A method for estimating a measure of the quality of a received signal in a computer simulation of an optical transmission system, wherein the simulation includes additive optical noise generated by optical amplifiers within the transmission system, the method including the steps of:

a) calculating one or more sets of parameters of a non-central chi square (x²) probability density function so as to approximate a suitable fit to the amplitude distribution of the received signal, including the effects of deterministic processing in the receiver but excluding the effects of statistical noise fluctuations introduced by the receiver;

b) calculating one or more sets of parameters of a non-gaussian probability density function that approximates a suitable fit to the amplitude distribution of the received signal, including the effects of deterministic processing and statistical noise fluctuations in the received signal using the calculated set(s) of parameters of the non-central x² probability density function and pre-specified statistical properties of the noise fluctuations introduced by the receiver; and

c) computing the measure of quality using the set(s) of parameters of the second non-gaussian probability density function.

11. A method for estimating a bit-error-rate of a received digital signal in a computer simulation of an optical transmission system, wherein the simulation includes additive optical noise generated by optical amplifiers within the transmission system, the method including the steps of:

a) calculating two sets of parameters of a non-central chi square (x²) probability density function so as to approximate a suitable fit to the amplitude distributions of data “

ones” and

data “

zeros”

of the received signal, including the effects of deterministic processing in the receiver but excluding the effects of statistical noise fluctuations introduced by the receiver;

b) calculating two sets of parameters of a non-gaussian probability density function that approximates a suitable fit to the amplitude distributions of date “

ones” and

data “

zeros”

of the received signal, including the effects of deterministic processing and statistical noise fluctuations in the receives signal using the calculated set(s) of parameters of the non-central x² probability density function and pre-specified statistical properties of the noise fluctuations introduced by the receiver wherein said statistical properties comprise a gaussian distribution characterized by its means and variance; and

c) computing the bit-error-rate using the set(s) of parameters of the second non-gaussian probability density function.

12. A computer program embodied on a computer readable medium for estimating a measure of the quality of a received signal in a computer simulation of an optical transmission system, the simulation including additive optical noise generated by components within the transmission system, the computer program including computer instruction code for:

a) calculating one or more sets of parameters of a first non-gaussian probability density function so as to approximate a suitable fit to the amplitude distribution of the received signal, including the effects of deterministic processing in the receiver but excluding the effects of statistical noise fluctuations introduced by the receiver;

b) calculating one or more sets of parameters of a second non-gaussian probability density function that approximates a suitable fit to the amplitude distribution of the received signal, including the effects of deterministic processing and statistical noise fluctuations in the received signal using the calculated set(s) of parameters of the first non-gaussian probability density function and pre-specified statistical properties of the noise fluctuations introduced by the receiver; and

c) computing the measure of quality using the set(s) of parameters of the second non-gaussian probability density function.

13. The computer program of claim 12 wherein said components of the transmission system include optical amplifiers.

14. The computer program of claim 13 wherein said optical amplifiers comprise erbium-doped fiber amplifiers.

15. The computer program of claim 12 wherein said statistical properties of the noise introduced by the receiver comprise a gaussian distribution characterized by its mean and variance.

16. The computer program of claim 12 wherein said first non-gaussian probability density function comprises a non-central chi square (x²) probability density function.

17. The computer program of claim 12 wherein said received signal comprises an intensity-modulated digital signal.

18. The computer program of claim 17 wherein said measure of the quality of the received signal comprises the bit-error-rate.

19. The computer program of claim 18 wherein at least two sets of parameters for each of said first and second non-gaussian probability density functions are calculated, corresponding respectively to the amplitude distributions of received data ‘

ones’ and

received data ‘

zeros’

.

20. The computer program claim 12 wherein said received signal is passed through a narrow optical filter prior to reception.

21. An apparatus for estimating a measure of the quality of the received signal in a computer simulation of an optical transmission system, wherein the simulation includes additive optical noise generated by components within the transmission system, the apparatus including:

a) means for calculating one or more sets of parameters of a first non-gaussian probability density function so as to approximate a suitable fit to the amplitude distribution of the received signal, including the effects of deterministic processing in the receiver but excluding the effects of statistical noise fluctuations introduced by the receiver;

b) means for calculating one or more sets of parameters of a second non-gaussian probability density function that approximates a suitable fit to the amplitude distribution of the received signal, including the effects of deterministic processing and statistical noise fluctuations in the received signal using the calculated set(s) of parameters of the first non-gaussian probability density function and pre-specified statistical properties of the noise fluctuations introduced by the receiver; and

c) means for computing the measure of quality using the set(s) of parameters of the second non-gaussian probability density function.

22. The apparatus of claim 21 wherein said components of the transmission system include optical amplifiers.

23. The apparatus of claim 21 wherein said first non-gaussian probability density function comprises a non-central chi square (x²) probability density function.

24. The apparatus of claim 21 wherein said received signal comprises an intensity-modulated digital signal, wherein said measure of the quality of the received signal comprises the bit-error-rate, and wherein at least two sets of parameters for each of said first and second non-gaussian probability density functions are calculated, corresponding respectively to the amplitude distributions of received data ‘

ones’ and

received data ‘

zeros’

.