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Hybrid fiber-coaxial (HFC) cable communication systems having well-aligned optical and radio-frequency links to facilitate upstream channel plans having high aggregate data capacity

  • US 8,949,918 B2
  • Filed: 03/17/2014
  • Issued: 02/03/2015
  • Est. Priority Date: 03/15/2013
  • Status: Active Grant
First Claim
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1. A hybrid fiber-coaxial (HFC) cable communication system, comprising:

  • a cable modem termination system (CMTS) having associated therewith at least one first attenuator to attenuate at least one upstream signal applied to the CMTS;

    an optical link communicatively coupled to the CMTS, the optical link having a dynamic range and comprising;

    an optical receiver having associated therewith at least one second attenuator to attenuate the at least one upstream signal; and

    an optical transmitter having associated therewith at least one third attenuator to attenuate the at least one upstream signal;

    a coaxial radio frequency (RF) link communicatively coupled to the optical link, the coaxial RF link comprising at least one RF amplifier having associated therewith at least one fourth attenuator to attenuate the at least one upstream signal, wherein the coaxial RF link includes an ingress-mitigated hardline cable plant; and

    at least one subscriber modem, communicatively coupled to the coaxial RF link, to generate from an output of the at least one subscriber modem the at least one upstream signal at a transmit RF signal level,wherein;

    the CMTS implements a long loop automatic level control (ALC) to set the transmit RF signal level of the at least one upstream signal generated from the output of the at least one subscriber modem, based at least in part on a received RF signal level of the at least one upstream signal as applied to the CMTS;

    respective values for the at least one first attenuator, the at least one second attenuator, the at least one third attenuator, and the at least one fourth attenuator are selected based at least in part on the dynamic range of the optical link so as to facilitate implementation of the long loop ALC and effective transmission to the CMTS of upstream information carried by the at least one upstream signal; and

    a value of the at least one fourth attenuator associated with the at least one RF amplifier is selected and/or adjusted such that a signal level of the at least one upstream signal at a junction of the coaxial RF link and the optical link corresponds to a predetermined input RF reference signal level to be applied to the optical link.

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