Information About OFDM Channel Power Profile
The OFDM power profile provides a better, consistent power-level output at the cable modem, compensating the power levels at a finer granularity. It reduces the differing amounts of cable-loss over the bandwidth of OFDM channel.
This feature enables the Cisco cBR Series Converged Broadband Router to correct the transmission loss due to the cable in the plant.
The OFDM power profile (ofdm-power-profile) adjusts the transmission power level of each 6 MHz in an OFDM channel. The OFDM channel width can range from 24 MHz to 192 MHz, resulting in band-counts between 4 and 32 for the profile.
Each 6 MHz band is referenced by a band index (band-index) that is zero-based, with a maximum band range of 192 MHz OFDM channel being 0 to 31. Each band within the OFDM channel can have a unique power level setting. The OFDM power profile allows a total band adjustment range of 8 dB. Under some specific conditions, if the OFDM channel's downstream controller's base channel power is set to exceed the maximum DRFI specification power level, the OFDM power profile adjustment range can become as high as 9 dB.
In a power profile, you can set the power level (power-adjust-default) to a default value. This default value is applied to any band that is not configured through any other means.
You can configure band power levels in two methods: through the power tilt config (power-tilt-linear) or by configuring the power level for a band or range of bands (band-index). You can use both methods for configuring the band power levels simultaneously within an OFDM power profile.
The power tilt configuration applies a linear power-adjust value between the
power-adjust-default value applied to the band index 0, and the power-tilt-linear adjust value applied to the highest band index of the profile.
For example, an OFDM Power Profile of 96 MHz, with a power-tilt-linear of 4 dB, and power-adjust-default of 0 dB, has16 bands
numbered 0 to 15, band index 0 is +0 dB, band index 15 is +4 dB, and bands 1 to 14 contain the linear power level setting
based on the slope of the line between the band 0 and band 15 to the nearest 1/10th dB.
The band-index configuration applies a specified value to the indicated bands. The band-index configuration can specify a single band or a range of bands. A power-adjust configuration is used to specify the power level for the bands to the nearest 1/10th dB.
You can simultaneously use both power tilt and band index, where band-index is applied last. When you use both, the power-tilt-linear values can be overridden using the band-index power-adjust values.
A maximum of 64 OFDM power profiles can be configured on the Cisco cBR routers, numbered from 1 to 64. You can apply a single OFDM power profile to multiple controller OFDM channels, across line cards, as long as all validity checks pass during configuration. The router console displays an error message explaining any configuration errors or warnings.
Restrictions for Configuring OFDM Power Profile
The following restrictions are applicable for configuring an OFDM power profile:
OFDM power profile can be configured only on DOCSIS 3.1 system
The power profile can be applied only to downstream controller OFDM channels (RF-channels 158 to 162)