Remote PHY QAM Profile Configuration

This document describes how to configure the QAM profile on the Cisco cBR Series Converged Broadband Router.

Your software release may not support all the features that are documented in this module. For the latest feature information and caveats, see the release notes for your platform and software release. The Feature Information Table at the end of this document provides information about the documented features and lists the releases in which each feature is supported.

Information About QAM Profile

A QAM profile describes the common downstream channel modulator settings, referred to as physical layer parameters. This includes QAM constellation, symbol rate, interleaver-depth, spectrum-inversion, and annex.

The QAM profile is described by CCAP DownPhyParams object. Default QAM profiles are supported and customized for DOCSIS or MPEG Video, which are described as DocsisPhyDefault and VideoPhyDefault objects, respectively.

A maximum of 32 QAM profiles can be defined. There are four system-defined QAM profiles (0 to 3), which cannot be deleted or modified. You can define profiles 4 to 31.

The system defined profiles are:

  • Profile 0 - default-annex-b-64-qam

    • interleaver-depth: I32-J4

    • symbol rate: 5057 kilo-symbol/second

    • spectrum-inversion: off

  • Profile 1 - default-annex-b-256-qam

    • interleaver-depth: I32-J4

    • symbol rate: 5361 kilo-symbol/second

    • spectrum-inversion: off

  • Profile 2 - default-annex-a-64-qam

    • interleaver-depth: I12-J17

    • symbol rate: 6952 kilo-symbol/second

    • spectrum-inversion: off

    Profile 3 - default-annex-a-256-qam

    • interleaver-depth: I12-J17

    • symbol rate: 6952 kilo-symbol/second

    • spectrum-inversion: off

How to Configure Remote PHY QAM Profile

Configuring the QAM Profile on Downstream Channels

Enable
configure terminal
  cabledownstream qam-profile Qam_Profile_ID D

   annex {A | B | C}
   description LINE
   interleaver-depth {I12-J17 | I128-J1 | I128-J2 |
I128-J3 | I128-J4 | I128-J5 | I128-J6 | I128-J7 |
I128-J8 | I16-J8 | I32-J4 | I64-J2 | I8-J16}
  modulation {256 | 64}   spectrum-inversion {off | on} 
  symbol-rate value
exit

You can configure symbol rate for Annex A video and Annex C video. The valid range for Annex A video is 3500 to 7000 kilo-symbols/sec. The valid range for Annex C video is 3500 to 5309 kilo-symbols/sec. The channel width in kHz is symbol-rate * (1 + alpha) with 0.15 alpha for Annex A and 0.13 alpha for Annex C.

Verifying QAM Profile on Downstream Channels

Use the following commands to verify the QAM Profile on Downstream Channels:

Router#show running-config | section downstream controller-profile
cable downstream controller-profile 0
 rf-chan 0 3
  type DOCSIS
  frequency 111000000
  rf-output NORMAL
  qam-profile 1
  docsis-channel-id 1

Configuration Example

QAM Profile Configuration

configure terminal 
  cable downstream controller-profile 1
    multicast-pool 20
    Rf-channel 0 15
     Type docsis
     Frequency 111000000
     Rf-output NORMAL
     Qam-profile 1
     Docsis-channel-id 1
  cable downstream controller-profile 2
    multicast-pool 20
    Rf-channel 20 47
     Type video sync
     Frequency 231000000
     Rf-output NORMAL
     Qam-profile 14

Feature Information for QAM Profile Configuration


Note

The following table lists the software release in which a given feature is introduced. Unless noted otherwise, subsequent releases of that software release train also support that feature.

Table 1. Feature Information for QAM Profile Configuration

Feature Name

Releases

Feature Information

QAM Profile Configuration-RPHY Annex B

Cisco 1x2 / Compact Shelf RPD Software 1.1

This feature was introduced on the Cisco Remote PHY Device.

QAM Profile Configuration-RPHY Annex A and C

Cisco 1x2 / Compact Shelf RPD Software 3.1

This feature was introduced on the Cisco Remote PHY Device.