Method and apparatus for determining modulation levels that are supported on a channel

• US 8,265,559 B2
• Filed: 01/30/2008
• Issued: 09/11/2012
• Est. Priority Date: 01/30/2007
• Status: Active Grant

• Current Assignee: ARRIS Enterprises LLC (CommScope Holding Company, Inc.)
• Original Assignee: General Instrument Corporation (CommScope Holding Company, Inc.)
• Inventors: Cooper, Michael J., Moore, Charles S., Moran, John L., Thibeault, Brian, Thompson, Robert J.
• Primary Examiner(s): HUANG, WEN WU
• Application Number:
  US12/022,249
• Publication Number:
  US 20080200129A1
• Time in Patent Office: 1,686 Days
• Field of Search: 455/44, 455/61, 455/102, 455/126, 455/509, 455/515, 455/67.11, 455/67.14, 725/105
• US Class Current: 455/44
• CPC Class Codes: G01R 29/06 Measuring depth of modulation
• CPC Class Codes: H04L 25/085 Arrangements for reducing interference in line transmission systems, e.g. by differential transmission
• CPC Class Codes: H04L 27/0008 arrangements for allowing a transmitter or receiver to use more than one type of modulation negotiating modulation type for two-way transmission paths H04L5/1453
• CPC Class Codes: H04L 27/0012 arrangements for identifying the type of modulation
• CPC Class Codes: H04L 43/50 Testing arrangements
• CPC Class Codes: H04L 5/1453 of modulation type
• CPC Class Codes: H04N 17/004 for digital television systems
• CPC Class Codes: H04N 21/238 Interfacing the downstream path of the transmission network, e.g. adapting the transmission rate of a video stream to network bandwidth; Processing of multiplex streams hybrid fiber coaxial [HFC] networks for downstream channel allocation for video distribution H04L12/2801; flow control in packet networks H04L47/10; real-time communication protocols in data switching networks H04L65/00; scheduling or organising the servicing of application requests H04L67/60
• CPC Class Codes: H04N 21/2383 Channel coding or modulation of digital bit-stream, e.g. QPSK modulation arrangements for detecting or preventing errors in the information received by adapting the channel coding H04L1/0009; analogue front ends or means for connecting modulators, demodulators or transceivers to a transmission line H04L27/0002
• CPC Class Codes: H04N 21/4382 Demodulation or channel decoding, e.g. QPSK demodulation analog front ends or means for connecting modulators, demodulators or transceivers to a transmission line H04L27/0002

Abstract

A logical channel is configured to match a modulation profile of an active channel. A network element is assigned to the logical channel and a ping request is sent to the network element. A response from the network element is measured, such as measuring the MER. The modulation profile is increased in the logical channel and another ping request is sent to the network element. The response is measured again, and the process is repeated until a non-linearity is detected in the response. The acceptable modulation profiles are indicated before the non-linearity is detected in the response.

Claims

1. An apparatus for monitoring a network comprising:

a microprocessor configured to;

configure a logical channel connectable to a test network element with a modulation profile that matches that of an active channel connected to the network, the logical channel separate from the active channel for coupling the test network element to a primary receiver,

reconfigure the logical channel with a non-matching modulation profile, wherein the non-matching modulation profile varies from the modulation profile used on the active channel connected to the network,

send a test signal to the test network element coupled to the logical channel configured with the non-matching modulation profile, and

determine whether the non-matching modulation profile is acceptable for communicating with the test network element using one or more characteristics of a response from the test signal; and

a receiver configured to receive the response to the test signal from the test network element via the logical channel.

2. The apparatus of claim 1, wherein the acceptable modulation profiles are determined based on one or more of:

signal to noise ratio, modulation error ratio, packet error rate, burst error rate, forward error correction error rates, network element transmit level, or signal distortion ratio.

3. The apparatus of claim 1, wherein the receiver is an undedicated receiver in a network.

4. The apparatus of claim 1, wherein the determination of acceptable modulation profiles does not impact existing network communications.

5. A method of for testing a network, the method comprising:

configuring a logical channel connectable to a test network element with a modulation profile that matches that of an active channel connected to the network for a selected network element, the active channel separate from the logical channel for coupling the selected network element to a primary receiver;

assigning the selected network element to the logical communication channel;

reconfiguring the logical channel with a non-matching modulation profile, wherein the non-matching modulation profile varies from the modulation profile used on the active channel connected to the network,

sending a communication to the selected network element via the logical communication channel configured with the non-matching modulation profile;

measuring one or more characteristics of a response received from the selected network element, the one or more characteristics describing transmission using the configured modulation profile; and

determining acceptable modulation profiles for communicating with the selected network element based on the one or more characteristics of the response.

6. The method of claim 5, wherein the one or more characteristics include one or more of:

signal to noise ratio, modulation error ratio, packet error rate, burst error rate, forward error correction error rates, network element transmit level, or signal distortion ratio.

7. The method of claim 5, wherein determining acceptable modulation profiles for communicating with the network element based on the one or more characteristics of the response comprises:

increasing the modulation profile of the logical communication channel to an increased modulation profile until determining the increased modulation profile is unacceptable.

8. The method of claim 7, wherein the modulation profile of the logical communication channel includes at least one of QPSK, 8QAM, 16QAM, 32QAM, 64QAM, 128QAM, or 256QAM.

9. The method of claim 7, wherein determining the increased modulation profile is unacceptable comprises:

detecting an impairment in the response received from the network element in one or more of the characteristics when the logical connection is configured to the increased modulation profile.

10. The method of claim 5, wherein the logical communication channel couples the selected network element to a spare receiver, the spare receiver separate from the primary receiver.

11. A non-transitory computer readable medium carrying instructions for a computer to perform a method of testing a network comprising:

configuring a logical channel connectable to a test network element with a modulation profile that matches that of an active channel connected to the network for a selected network element, the active channel separate from the logical channel for coupling the selected network element to a primary receiver;

assigning the selected network element to the logical communication channel;

reconfiguring the logical channel with a non-matching modulation profile, wherein the non-matching modulation profile varies from the modulation profile used on the active channel connected to the network,

sending a communication to the selected network element via the logical communication channel configured with the non-matching modulation profile;

measuring one or more characteristics of a response received from the selected network element, the one or more characteristics describing transmission using the configured modulation profile; and

determining acceptable modulation profiles for communicating with the selected network element based on the one or more characteristics of the response.

12. The computer readable medium of claim 11, wherein the one or more characteristics include one or more of:

signal to noise ratio, modulation error ratio, packet error rate, burst error rate, forward error correction error rates, network element transmit level, or signal distortion ratio.

13. The computer readable medium of claim 11, wherein determining acceptable modulation profiles for communicating with the network element based on the one or more characteristics of the response comprises:

increasing the modulation profile of the logical communication channel to an increased modulation profile until determining the increased modulation profile is unacceptable.

14. The computer readable medium of claim 13, wherein the modulation profile of the logical communication channel includes at least one of QPSK, 8QAM, 16QAM, 32QAM, 64QAM, 128QAM, or 256QAM.

15. The computer readable medium of claim 13, wherein determining the increased modulation profile is unacceptable comprises:

detecting an impairment in the response received from the network element in one or more of the characteristics when the logical connection is configured to the increased modulation profile.

16. The computer readable medium of claim 11 wherein the logical communication channel couples the selected network element to a spare receiver, the spare receiver separate from the primary receiver.