Method and apparatus for characterizing modulation schemes in an HFC network
First Claim
1. An apparatus for characterizing modulation schemes for a network comprising:
- a controller configured to instruct a network element to transmit a test signal at a test frequency, a first modulation scheme and a first power level;
a receiver configured to receive the test signal from the network element; and
a multiple tap equalizer which measures a signal to noise ratio of the test signal based on measurement of at least one of a packet error rate, a modulation error ratio, or a bit error rate of the test signal,wherein the controller determines if the signal to noise ratio is within a predetermined range of an estimated signal to noise ratio, and the controller determines that the modulation scheme has excessive inband interference or phase noise when the signal to noise ratio is not within a predetermined range of an estimated signal to noise ratio,wherein the controller is further configured to instruct the network element to transmit a second test signal at a second modulation scheme different from the first modulation scheme, and to determine if a second signal to noise ratio associated with the second test signal is within a predetermined range of a second estimated signal to noise ratio, and the controller determines that the second modulation scheme has excessive inband interference or phase noise when the second signal to noise ratio is not within a predetermined range of the second estimated signal to noise ratio,wherein the controller is further configured to determine which modulation schemes provide a signal to noise ratio is within a predetermined range of an estimated signal to noise ratio.
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Accused Products
Abstract
The available modulation schemes of a network are analyzed to determine which ones contain excessive phase noise or narrowband interference. A network element is selected and assigned to a test channel at a first modulation scheme at a predetermined power level to achieve a predetermined PER. The network element transmits a test signal and the network controller measures the signal to noise ratio (SNR) in the received test signal. If the SNR is not within a predetermined tolerance range of an estimated SNR for the modulation scheme at the predetermined PER, the modulation scheme is determined to have excessive phase noise or narrowband interference. Each available modulation scheme is tested by instructing the network element to transmit the test signal using each modulation scheme and assigning the power level of each modulation scheme. The suitable modulation schemes may be determined.
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Citations
20 Claims
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1. An apparatus for characterizing modulation schemes for a network comprising:
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a controller configured to instruct a network element to transmit a test signal at a test frequency, a first modulation scheme and a first power level; a receiver configured to receive the test signal from the network element; and a multiple tap equalizer which measures a signal to noise ratio of the test signal based on measurement of at least one of a packet error rate, a modulation error ratio, or a bit error rate of the test signal, wherein the controller determines if the signal to noise ratio is within a predetermined range of an estimated signal to noise ratio, and the controller determines that the modulation scheme has excessive inband interference or phase noise when the signal to noise ratio is not within a predetermined range of an estimated signal to noise ratio, wherein the controller is further configured to instruct the network element to transmit a second test signal at a second modulation scheme different from the first modulation scheme, and to determine if a second signal to noise ratio associated with the second test signal is within a predetermined range of a second estimated signal to noise ratio, and the controller determines that the second modulation scheme has excessive inband interference or phase noise when the second signal to noise ratio is not within a predetermined range of the second estimated signal to noise ratio, wherein the controller is further configured to determine which modulation schemes provide a signal to noise ratio is within a predetermined range of an estimated signal to noise ratio. - View Dependent Claims (2, 3, 4, 5)
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6. A method for characterizing modulation schemes for a network comprising the steps of:
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selecting a network element to transmit a test signal at a test frequency, a first modulation scheme and a first power; receiving the test signal from the network element; measuring a signal to noise ratio of the test signal based on measurement of at least one of a packet error rate, a modulation error ratio, or a bit error rate of the test signal; determining if the signal to noise ratio is within a predetermined range of an estimated signal to noise ratio, and determining that the modulation scheme has excessive inband interference or phase noise when the signal to noise ratio is not within a predetermined range of an estimated signal to noise ratio, instructing the network element to transmit a second test signal at a second modulation scheme different from the first modulation scheme, determining if a second signal to noise ratio associated with the second test signal is within a predetermined range of a second estimated signal to noise ratio, determining that the second modulation scheme has excessive inband interference or phase noise when the second signal to noise ratio is not within a predetermined range of the second estimated signal to noise ratio, and determining which modulation schemes provide a signal to noise ratio is within a predetermined range of an estimated signal to noise ratio. - View Dependent Claims (7, 8, 9, 10)
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11. A computer readable medium carrying instructions for a computer to perform a method for characterizing modulation schemes for a network comprising the steps of:
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selecting a network element to transmit a test signal at a test frequency at a first modulation scheme and a first power; receiving the test signal from the network element; measuring a signal to noise ratio of the test signal based on measurement of at least one of a packet error rate, a modulation error ratio, or a bit error rate of the test signal; determining if the signal to noise ratio is within a predetermined range of an estimated signal to noise ratio, and determining that the modulation scheme has excessive inband interference or phase noise when the signal to noise ratio is not within a predetermined range of an estimated signal to noise ratio, instructing the network element to transmit a second test signal at a second modulation scheme different from the first modulation scheme, determining if a second signal to noise ratio associated with the second test signal is within a predetermined range of a second estimated signal to noise ratio, determining that the second modulation scheme has excessive inband interference or phase noise when the second signal to noise ratio is not within a predetermined range of the second estimated signal to noise ratio, and determining which modulation schemes provide a signal to noise ratio is within a predetermined range of an estimated signal to noise ratio. - View Dependent Claims (12, 13, 14, 15)
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16. A network comprising:
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a controller configured to instruct a network element to transmit a test signal at a test frequency at a first modulation scheme and a first power; a receiver configured to receive the test signal from the network element; and an equalizer which measures a signal to noise ratio of the test signal based on measurement of at least one of a packet error rate, a modulation error ratio, or a bit error rate of the test signal, wherein the controller determines if the signal to noise ratio is within a predetermined range of an estimated signal to noise ratio, and the controller determines that the modulation scheme has excessive inband interference or phase noise when the signal to noise ratio is not within a predetermined range of an estimated signal to noise ratio, wherein the controller is further configured to instruct the network element to transmit a second test signal at a second modulation scheme different from the first modulation scheme, and to determine if a second signal to noise ratio associated with the second test signal is within a predetermined range of a second estimated signal to noise ratio, and the controller determines that the second modulation scheme has excessive inband interference or phase noise when the second signal to noise ratio is not within a predetermined range of the second estimated signal to noise ratio wherein the controller is further configured to determine which modulation schemes provide a signal to noise ratio is within a predetermined range of an estimated signal to noise ratio. - View Dependent Claims (17, 18, 19, 20)
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Specification