Method and Apparatus for Determining the Dynamic Range of an Optical Link in an HFC Network

Abstract

The dynamic range of an optical link in a network is determined by simultaneously transmitting signals from two network elements at first and second frequencies, which create a combined signal at a third frequency. The transmission power levels of selected network elements is successively increased until the measured power from the third frequency no longer changes in a predicatable manner, at which point the upper limit of the dynamic range of the optical link is determined.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

The following drawings serve to illustrate the principles of the invention.

FIG. 1 illustrates an exemplary network in accordance with the principles of the invention.

FIG. 2 illustrates an exemplary CMTS architecture in accordance with the principles of the invention.

FIG. 3 illustrates an exemplary receiver arrangement which may communicate with an exemplary CMTS of the present invention.

FIG. 4 illustrates an exemplary architecture of an optical transceiver in a headend which may contain an exemplary CMTS of the present invention.

FIG. 5 illustrates an exemplary architecture of a network element which may communicate with an exemplary CMTS of the present invention.

FIG. 6 illustrates an exemplary process in accordance with the principles of the present invention.

Claims

1. An apparatus for measuring a network comprising: a controller configured to instruct a first network element to transmit a first signal at a first frequency f1 and a second network element to transmit a second signal at a second frequency f2 so that the first signal and the second signal are received by a common node at the same time;a receiver configured to receive communications on a third frequency f3 based on the first signal from the first network element and the second signal from the second network element, whereby the third frequency f3 is a combination of the first signal from the first network element at the first frequency f1 and the second signal from the second network element at the second frequency f2; anda power monitoring unit which is configured to measure power in signals contained in the third frequency,wherein the controller is configured to determine a dynamic range of an optical link based on the measured power in the signals contained in the third frequency.

2. The apparatus of claim 1, wherein the power monitoring unit is further configured to measure power in an expected frequency bandwidth of the third frequency, the expected frequency bandwidth being less than an assigned communication bandwidth of an upstream communication bandwidth of the network.

3. The apparatus of claim 2, wherein the power monitoring unit is further configured to measure power in a 1 MHz bandwidth around the third frequency f3.

4. The apparatus of claim 1, wherein the controller is configured to determine an upper limit to the dynamic range of the optical link by determining when an increase in power level in frequency f3 is not in a predictable manner.

5. The apparatus of claim 4, wherein the controller is configured to instruct at least one of the first network element or the second network element to increase transmission power of the first signal or the second signal, respectively, when the upper limit of the dynamic range of the optical link has not been reached.

6. The apparatus of claim 1, wherein the first frequency f1 and the second frequency f2 are selected so that an interaction between f1 and f2 produces an intermodulation frequency at the third frequency f3 in a transmitting laser in the node.

7. A method for determining a dynamic range of an optical link in a network comprising the steps of: selecting a first network element to transmit a first signal at a first frequency f1 and a second network element to transmit a second signal at a second frequency f2 so that the first signal and the second signal are received by a common node at the same time;receiving communications on a third frequency f3, whereby the third frequency f3 is a combination of the first signal from the first network element at the first frequency f1 and the second signal from the second network element at the second frequency f2;measuring power in signals contained in the third frequency; anddetermining a dynamic range of an optical link based on the measured power in the signals contained in the third frequency.

8. The method of claim 7, wherein the step of measuring power measures power in an expected frequency bandwidth of the third frequency, the expected frequency bandwidth being less than an assigned communication bandwidth of an upstream communication bandwidth of the network.

9. The method of claim 8, wherein the step of measuring power measures power in a 1 MHz bandwidth around the third frequency f3.

10. The method of claim 7, wherein the step of determining a dynamic range of an optical link determines an upper limit to the dynamic range of the optical link by determining when an increase in power level in frequency f3 is not in a predictable manner.

11. The method of claim 7, further comprising the step of instructing at least one of the first network element or the second network element to increase transmission power of the first signal or the second signal, respectively, when an upper limit of the dynamic range of the optical link has not been reached.

12. The method of claim 7, wherein the first frequency f1 and the second frequency f2 are selected so that an interaction between f1 and f2 produces an intermodulation frequency at the third frequency f3 in a transmitting laser in the node.

13. A computer readable medium carrying instructions for a computer to perform a method for determining a dynamic range of an optical link in a network comprising the steps of: selecting a first network element to transmit a first signal at a first frequency f1 and a second network element to transmit a second signal at a second frequency f2 so that the first signal and the second signal are received by a common node at the same time;receiving communications on a third frequency f3, whereby the third frequency f3 is a combination of the first signal from the first network element at the first frequency f1 and the second signal from the second network element at the second frequency f2;measuring power in signals contained in the third frequency; anddetermining a dynamic range of an optical link based on the measured power in the signals contained in the third frequency.

14. The computer readable medium of claim 13, wherein the step of measuring power measures power in an expected frequency bandwidth of the third frequency, the expected frequency bandwidth being less than an assigned communication bandwidth of an upstream communication bandwidth of the network.

15. The computer readable medium of claim 14, wherein the step of measuring power measures power in a 1 MHz bandwidth around the third frequency f3.

16. The computer readable medium of claim 13, wherein the step of determining a dynamic range of an optical link determines an upper limit to the dynamic range of the optical link by determining when an increase in power level in frequency f3 is not in a predictable manner.

17. The computer readable medium of claim 13, further comprising the step of instructing at least one of the first network element or the second network element to increase transmission power of the first signal or the second signal, respectively, when an upper limit of the dynamic range of the optical link has not been reached.

18. The computer readable medium of claim 13, wherein the first frequency f1 and the second frequency f2 are selected so that an interaction between f1 and f2 produces an intermodulation frequency at the third frequency f3 in a transmitting laser in the node.