Cable communication system optical nodes having selectable attenuation values to mitigate distortion of upstream information
First Claim
1. An optical node in a cable communication system, the optical node comprising:
- an upstream RF port to couple the optical node to an ingress-mitigated hardline RF cable plant of the cable communication system, the ingress-mitigated hardline RF cable plant conveying upstream RF information via an upstream channel plan in an upstream path bandwidth of the ingress-mitigated hardline RF cable plant, the upstream channel plan including a plurality of upstream RF signals, each upstream RF signal of the plurality of upstream RF signals including an encoded carrier wave having a carrier frequency in the upstream path bandwidth;
at least one RF attenuator communicatively coupled to the upstream RF port to attenuate the plurality of upstream RF signals received by the optical node via the upstream RF port so as to provide a plurality of attenuated upstream RF signals; and
an upstream optical transmitter communicatively coupled to the at least one RF attenuator to receive the plurality of attenuated upstream RF signals carrying the upstream RF information and to transmit corresponding upstream optical information via an optical communication link communicatively coupled to the upstream optical transmitter,wherein;
the at least one attenuator of the optical node has an attenuation value to significantly mitigate substantial distortion of the upstream optical information transmitted by the upstream optical transmitter such that the upstream optical information is an effective copy of the upstream RF information;
each upstream RF signal of the plurality of upstream RF signals is modulated, using quadrature amplitude modulation (QAM), with voice and/or data information constituting at least some of the upstream RF information;
the plurality of upstream RF signals includes a first upstream RF signal defining a first upstream physical communication channel of the upstream channel plan in the upstream path bandwidth, the first upstream RF signal having a first carrier frequency of greater than or equal to approximately 5 MHz, and less than or equal to approximately 19.6 MHz;
at least some of the plurality of upstream RF signals have different carrier frequencies to respectively define a plurality of upstream physical communication channels constituting the upstream channel plan in the upstream path bandwidth;
the plurality of upstream physical communication channels occupy a substantial portion of the upstream path bandwidth;
the upstream path bandwidth includes carrier frequencies in a range of from approximately 5 MHz to at least approximately 42 MHz;
the upstream channel plan includes at least four physical communication channels respectively defined by upstream signals having a QAM modulation order of at least 64;
the first carrier frequency of the first upstream RF signal is greater than or equal to approximately 5 MHz, and less than or equal to approximately 16.4 MHz; and
the first upstream RF signal has a QAM modulation order of at least 32.
1 Assignment
0 Petitions
Accused Products
Abstract
An HFC cable communication system comprising: a CMTS having a first attenuator to attenuate one or more upstream signals applied to the CMTS; an optical link having a dynamic range and comprising an optical receiver having a second attenuator to attenuate the upstream signal(s) and an optical transmitter having a third attenuator to attenuate the upstream signal(s); a coaxial RF link comprising one or more RF amplifiers having a fourth attenuator to attenuate the upstream signal(s); and one or more subscriber modems to generate the upstream signal(s) at respective transmit RF signal levels. The CMTS implements a long loop ALC to set the transmit RF signal level(s) based on received RF signal levels of the upstream signal(s) at the CMTS. Respective values for the first, second, third and fourth attenuators are selected based on the dynamic range of the optical link so as to facilitate implementation of the long loop ALC and effective transmission of upstream information carried by the upstream signal(s).
47 Citations
29 Claims
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1. An optical node in a cable communication system, the optical node comprising:
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an upstream RF port to couple the optical node to an ingress-mitigated hardline RF cable plant of the cable communication system, the ingress-mitigated hardline RF cable plant conveying upstream RF information via an upstream channel plan in an upstream path bandwidth of the ingress-mitigated hardline RF cable plant, the upstream channel plan including a plurality of upstream RF signals, each upstream RF signal of the plurality of upstream RF signals including an encoded carrier wave having a carrier frequency in the upstream path bandwidth; at least one RF attenuator communicatively coupled to the upstream RF port to attenuate the plurality of upstream RF signals received by the optical node via the upstream RF port so as to provide a plurality of attenuated upstream RF signals; and an upstream optical transmitter communicatively coupled to the at least one RF attenuator to receive the plurality of attenuated upstream RF signals carrying the upstream RF information and to transmit corresponding upstream optical information via an optical communication link communicatively coupled to the upstream optical transmitter, wherein; the at least one attenuator of the optical node has an attenuation value to significantly mitigate substantial distortion of the upstream optical information transmitted by the upstream optical transmitter such that the upstream optical information is an effective copy of the upstream RF information; each upstream RF signal of the plurality of upstream RF signals is modulated, using quadrature amplitude modulation (QAM), with voice and/or data information constituting at least some of the upstream RF information; the plurality of upstream RF signals includes a first upstream RF signal defining a first upstream physical communication channel of the upstream channel plan in the upstream path bandwidth, the first upstream RF signal having a first carrier frequency of greater than or equal to approximately 5 MHz, and less than or equal to approximately 19.6 MHz; at least some of the plurality of upstream RF signals have different carrier frequencies to respectively define a plurality of upstream physical communication channels constituting the upstream channel plan in the upstream path bandwidth; the plurality of upstream physical communication channels occupy a substantial portion of the upstream path bandwidth; the upstream path bandwidth includes carrier frequencies in a range of from approximately 5 MHz to at least approximately 42 MHz; the upstream channel plan includes at least four physical communication channels respectively defined by upstream signals having a QAM modulation order of at least 64; the first carrier frequency of the first upstream RF signal is greater than or equal to approximately 5 MHz, and less than or equal to approximately 16.4 MHz; and the first upstream RF signal has a QAM modulation order of at least 32. - View Dependent Claims (2)
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3. An optical node in a cable communication system, the optical node comprising:
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an upstream RF port to couple the optical node to an ingress-mitigated hardline RF cable plant of the cable communication system, the ingress-mitigated hardline RF cable plant conveying upstream RF information via an upstream channel plan in an upstream path bandwidth of the ingress-mitigated hardline RF cable plant, the upstream channel plan including a plurality of upstream RF signals, each upstream RF signal of the plurality of upstream RF signals including an encoded carrier wave having a carrier frequency in the upstream path bandwidth; at least one RF attenuator communicatively coupled to the upstream RF port to attenuate the plurality of upstream RF signals received by the optical node via the upstream RF port so as to provide a plurality of attenuated upstream RF signals; and an upstream optical transmitter communicatively coupled to the at least one RF attenuator to receive the plurality of attenuated upstream RF signals carrying the upstream RF information and to transmit corresponding upstream optical information via an optical communication link communicatively coupled to the upstream optical transmitter, wherein; the at least one attenuator of the optical node has an attenuation value to significantly mitigate substantial distortion of the upstream optical information transmitted by the upstream optical transmitter such that the upstream optical information is an effective copy of the upstream RF information; the upstream optical transmitter has a dynamic range that is based at least in part on the upstream channel plan; the attenuation value of the at least one attenuator of the optical node is selected based at least in part on the dynamic range of the upstream optical transmitter; and the dynamic range of the optical transmitter is based at least in part on a highest QAM modulation order of at least one upstream physical communication channel of the upstream channel plan. - View Dependent Claims (4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23)
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24. An optical node in a cable communication system, the optical node comprising:
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A) an upstream RF port to couple the optical node to an RF cable plant of the cable communication system, the RF cable plant conveying upstream RF information via an upstream channel plan in an upstream path bandwidth of the RF cable plant, wherein; the upstream channel plan includes a plurality of upstream RF signals, each upstream RF signal of the plurality of upstream RF signals including an encoded carrier wave having a carrier frequency in the upstream path bandwidth; each upstream RF signal of the plurality of upstream RF signals is modulated, using quadrature amplitude modulation (QAM), with voice and/or data information constituting at least some of the upstream RF information; and at least one first upstream signal of the plurality of upstream signals has a QAM modulation order of 32 and a first carrier frequency of between approximately 5 MHz and 19.6 MHz; B) at least one RF attenuator communicatively coupled to the upstream RF port to attenuate the plurality of upstream RF signals received by the optical node via the upstream RF port so as to provide a plurality of attenuated upstream RF signals; and C) an upstream optical transmitter communicatively coupled to the at least one RF attenuator to receive the plurality of attenuated upstream RF signals carrying the upstream RF information and to transmit corresponding upstream optical information via an optical communication link communicatively coupled to the upstream optical transmitter, the upstream optical transmitter having a dynamic range that is based at least in part on; a highest QAM modulation order of at least one upstream physical communication channel of the channel plan; and an information transfer characteristic of the upstream optical transmitter, wherein; an attenuation value of the at least one attenuator of the optical node is selected based at least in part on the dynamic range of the upstream optical transmitter so as to significantly mitigate substantial distortion of the upstream optical information transmitted by the upstream optical transmitter such that the upstream optical information is an effective copy of the upstream RF information. - View Dependent Claims (25)
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26. An optical node in a cable communication system, the optical node comprising:
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A) an upstream RF port to couple the optical node to an RF cable plant of the cable communication system, the RF cable plant conveying upstream RF information via an upstream channel plan in an upstream path bandwidth of the RF cable plant, wherein; the upstream channel plan includes a plurality of upstream RF signals, each upstream RF signal of the plurality of upstream RF signals including an encoded carrier wave having a carrier frequency in the upstream path bandwidth; each upstream RF signal of the plurality of upstream RF signals is modulated, using quadrature amplitude modulation (QAM), with voice and/or data information constituting at least some of the upstream RF information; at least some of the plurality of upstream signals have different carrier frequencies to respectively define a plurality of upstream physical communication channels in the upstream path bandwidth constituting a channel plan; a first upstream signal defining a first upstream physical communication channel of the plurality of upstream physical communication channels has a first carrier frequency of less than 19.6 MHz; and the channel plan includes at least four physical communication channels respectively defined by upstream signals having a QAM modulation order of at least 64; B) at least one RF attenuator communicatively coupled to the upstream RF port to attenuate the plurality of upstream RF signals received by the optical node via the upstream RF port so as to provide a plurality of attenuated upstream RF signals; and C) an upstream optical transmitter communicatively coupled to the at least one RF attenuator to receive the plurality of attenuated upstream RF signals carrying the upstream RF information and to transmit corresponding upstream optical information via an optical communication link communicatively coupled to the upstream optical transmitter, wherein; an attenuation value of the at least one attenuator of the optical node is selected based at least in part on; a highest QAM modulation order of at least one upstream physical communication channel of the channel plan; and an information transfer characteristic of the upstream optical transmitter. - View Dependent Claims (27)
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28. An optical node in a cable communication system, the optical node comprising:
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A) an upstream RF port to couple the optical node to an RF cable plant of the cable communication system, the RF cable plant conveying upstream RF information via an upstream channel plan in an upstream path bandwidth of the RF cable plant, wherein; the upstream channel plan includes a plurality of upstream RF signals, each upstream RF signal of the plurality of upstream RF signals including an encoded carrier wave having a carrier frequency in the upstream path bandwidth; each upstream RF signal of the plurality of upstream RF signals is modulated, using quadrature amplitude modulation (QAM), with voice and/or data information constituting at least some of the upstream RF information; each upstream RF signal of the plurality of upstream RF signals has a signal level at the upstream RF port corresponding to a predetermined input RF reference signal level; at least some of the plurality of upstream signals have different carrier frequencies to respectively define a plurality of upstream physical communication channels in the upstream path bandwidth constituting a channel plan; and a first upstream signal defining a first upstream physical communication channel of the plurality of upstream physical communication channels has a first carrier frequency of less than 19.6 MHz; B) at least one RF attenuator communicatively coupled to the upstream RF port to attenuate the plurality of upstream RF signals received by the optical node via the upstream RF port so as to provide a plurality of attenuated upstream RF signals; and C) an upstream optical transmitter communicatively coupled to the at least one RF attenuator to receive the plurality of attenuated upstream RF signals carrying the upstream RF information and to transmit corresponding upstream optical information via an optical communication link communicatively coupled to the upstream optical transmitter, wherein; the upstream optical transmitter has a dynamic range defined by an input RF power window for the plurality of upstream RF signals as applied to the upstream optical transmitter of the optical link, the input RF power window determined by at least one intersection of
1) a target carrier-to-noise (C/N) value for a highest QAM modulation order of at least one upstream physical communication channel of the channel plan and
2) a Noise Power Ratio (NPR) curve for the upstream optical transmitter;a target operating power point for the upstream optical transmitter is selected within the input RF power window; and an attenuation value of the at least one attenuator of the optical node is selected based at least in part on a difference between the target operating power point for the optical transmitter and the predetermined input RF reference signal level. - View Dependent Claims (29)
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Specification