spectrum managment.pdf

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………………………………………Spectrum Management Operations

Module #6



Introduction

The RiverClear spectrum management system monitors theupstream signal integrity,and collects upstream spectrum

information. When signal integrity degrades due to noise, the

spectrum management system automatically configures theupstream channel parameters to maintain low packet loss by

changing the upstream frequency,power, channel-width,

and/or modulation profile to ensure that upstreamperformance stays at acceptable levels.



Spectrum Management

The following tasks are used to implement frequency agility onthe BSR:

• Configuring Spectrum Groups

• Applying a Spectrum Group to an Upstream Port

• Showing Spectrum Data



Configuring Spectrum Groups

Each spectrum group contains spectrum data, spectrum map, and channel assignment:

The spectrum data is where the collected spectrum noise information is kept. It containsstarting frequency,Resolution, number of data points, time of the last measurement,

and a pointer to an array where the noise level is kept.

The spectrum map describes the way the upstream spectrum is used for a particular

band. It contains the start and stop frequency, and the current status.

The channel assignment defines the frequency allocation of the upstream channel.



Configuring Spectrum Groups

Spectrum signal quality information is collected through the spectrum monitoring process. This

information contains the periodic error rate that is computed and compared with the Forward

Error Correction (FEC) error threshold to determine if spectrum hopping is necessary, and the

periodic combination of in-band power and spectrum data collection to compute signal-to-noiseratio (SNR) for the upstream channel.

The spectrum schedule contains information on the availability of a certain frequency band.

The band can be made available statically, or available only at certain time period(s). Theactual available spectrum is the super set of all the bands that are available at the time.

Spectrum hopping rules determine the action taken when the spectrum manager decides tochange the upstream parameters of a channel to combat noise.

Operators can specify power adjustments, modulation profile changes, and channel-width

reduction until channel conditions improve.



Defining Spectrum Groups

• Creating a Spectrum Group

• Scheduling the Availability of a Spectrum

Group Band

• Scheduling the Removal of a Spectrum Group

Band

• Configuring Spectrum Data Collection

• Manually Collecting Spectrum Data

• Configuring Spectrum Hopping Rules

• Configuring the Spectrum Hopping Threshold

• Enabling and Disabling Spectrum Roll-back

• Configuring the Guard Band

• Viewing Your Spectrum Group



Spectrum Groups

Creating a Spectrum Group

RDN(config)#cable spectrum <group-name>

where:

group-name is the spectrum group name.



Spectrum Groups

RDN(config-spcgrp:spectrum 1)#

Use the band command in Cable Spectrum Group mode to define the start andend frequency band for the spectrum group, as shown below:

RDN(config-spcgrp:<group-name>)#band {<star t> <end>}

where:group-name is the spectrum group name that you defined.

start is the start upstream frequency from 5000000 to 65000000 Hertz.

end is the end upstream frequency from 5000000 to 65000000 Hertz.

RDN(config-spcgrp:spectrum 1)#band 8000000 12000000



Spectrum Groups

Time Allocation of Spectrum GroupsRDN(config-spcgrp:< group-name>)#time <hh:mm:ss> band {< star t> <end>}

where:

group-name is the spectrum group name.

RDN(config-spcgrp:< group-name>)#time {<day> <hh:mm:ss>} band

{< star t> <end>}

For example, the following syntax is used to express that the band from 27 MHz to 29 MHz, belonging

to spectrum group spectrum 1, is available every Thursday morning at 10:00 AM:

RDN(config-spcgrp:spectrum 1)#time Thursday 10:00:00 band 27000000 29000000



Configuring Spectrum Data

CollectionUse the collect resolution command in Cable Spectrum Group mode to configure the frequency

resolution rate that the spectrum manager performs, as shown below:

RDN(config-spcgrp:<group-name>)#collect resolution <H z>

where: Hz is the resolution in Hertz from 200000 to 3200000. The default resolution is 200000 Hz.

Use the collect interval command in Cable Spectrum Group mode to configure the interval rate at

which data collection is performed by the spectrum manager:

RDN(config-spcgrp:<group-name>)#collect interval <seconds>

where: seconds is the time interval from 60 to 65535 seconds.

Use the collect spectrum-data cable upstream command in Privileged EXEC mode

to collect spectrum data information manually, as shown in the following example

RDN#collect spectrum-data cable <slot>/<port> upstream <n>

where:

slot is the DOCSIS module number, port is the cable interface number, n is the upstream port number



Configuring Spectrum Hopping

RulesRules for spectrum hopping must be defined before the spectrum hopping function is used.

Spectrum hopping rules are searched before spectrum hopping occurs on an upstream port whenthe spectrum group is triggered. Spectrum hopping rules are used by the spectrum manager to

find the best way to defeat noise problems on an upstream port.

The following spectrum hopping rules apply:

• No actions are taken if spectrum hopping rules are not defined. The rules include

the preferred frequency, power adjustment, modulation profile, and channel-width parameters.

• Multiple hopping rules with same type of action are allowed.

• Each hopping rule can be assigned with different priorities.

• Hopping rules are applied by priority and hopping rules with same priority are

applied in the order in which they are entered.

C fi i S H i




Rules1. To prevent excessive frequency hops on an upstream port, use the hop period command in Cable Spectrum

Group mode, as shown below:

RDN(config-spcgrp:<group-name>)#hop period <second s>

where: seconds is the rate at which the frequency hop takes place from 1 to 3600 seconds. The default hop periodis 300 seconds.

2. Use the hop action frequency command in Cable Spectrum Group mode to determine the frequency search

order for either discrete center frequencies or frequency bands during the frequency hop action, as shown below:

RDN(config-spcgrp:<group-name>)#hop action frequency <frequenc y> [priority <n>]

where:

frequency is the upstream frequency from 5000000 to 42000000 Hz

n is the priority number of the upstream frequency hop action from 1 to 255.

When no priority is assigned, the default priority is 128.

3. Use the hop action band command in Cable Spectrum Group mode to determine the search order for each

frequency band during the frequency hop action, as shown below:

RDN(config-spcgrp:<group-name>)#hop action band {<star t> <end>} [priority <n>]

where: start is the start upstream frequency band from 5000000 to 65000000 Hz.end is the end upstream frequency band from 5000000 to 65000000 Hz.

n is the priority number of the upstream band hop action from 1 to 255.

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RulesUse the hop action power-level command in Cable Spectrum Group mode to change the power-level setting

before a frequency hop action, as shown below:

RDN(config-spcgrp:<group-name>)#hop action power-level {< power> | default <offset>}[priority <n>]

where: power is the input power level, expressed in dB.

offset is the number of dB above or below the default Input power level.

n is the priority number of the upstream power level hop action. When no priority is assigned, the

default priority is 128.

Use the hop action modulation-profile command in Cable Spectrum Group mode to change the modulation

profile setting before a frequency hop action, as shown below:

RDN(config-spcgrp:<group-name>)#hop action modulation-profile <profile-number> [priority <n>]

where: profile-number is the modulation profile number. The default modulation profiles are 1 and 2.

n is the priority number of the upstream modulation profile hop action. When no priority is assigned,

the default priority is 128.

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Rules

Use the hop action channel-width command in Cable Spectrum Group mode to

change the upstream channel-width setting before a frequency hop action, as shown below:

RDN(config-spcgrp:<group-name>)#hop action channel-width <widt h> [priority <n>]

where: width is the upstream channel width setting.

n is the priority number of the upstream channel width setting. When no

priority is assigned, the default priority is 128.

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Thresholds

A frequency hopping threshold is configured to prevent unnecessary frequency hops in instances when one

or a minimal number of cable modems (CMs) loose their connection with the BSR.

The frequency hopping threshold is determined by the percentage of CMs that loose their connectivity. The

default frequency hopping threshold is 100 percent.

Use the hop threshold flap command in Cable Spectrum Group mode to trigger when a greater than a setpercentage of CMs loose their connectivity.

RDN(config-spcgrp:<group-name>)#hop threshold flap <percent>

where: percent is the percentage of CMs that loose connectivity

E bli d Di bli S t



Enabling and Disabling Spectrum

Roll-back

The spectrum roll-back function is disabled by default. The spectrum roll-back function is used to

return the upstream channel width or modulation profile setting, that was adjusted during a hopaction, to the original configuration when upstream channel conditions improve.

To enable the spectrum roll-back function, use the hop action rollback command in Cable Spectrum

Group mode as shown below:

RDN(config-spcgrp:<group-name>)#hop action rollback

To disable the spectrum roll-back function, use the no hop action rollback command.

C fi i th G d B d



Configuring the Guard Band

Use the guard-band command in Cable Spectrum Group mode to set the minimum

spectrum separation or spacing between upstream channels in the same spectrum

group.

RDN(config-spcgrp:<group-name>)#guard-band <n>

where:

n is the guard band separation size from 0 to 60000000 Hz. Default guard band is 1000 Hz.

Viewing Your Spectrum Group




To view the spectrum group that you created, enter the show cable spectrum-

group command in Global Configuration mode, as shown in the following

example:

RDN(config)#show cable spectrum-group <group-name>

where: group-name is the spectrum group name.

Applying a Spectrum Group to an



Applying a Spectrum Group to an

Upstream PortWhen a spectrum group is applied to an upstream port, the upstream port belongs to the spectrum group.

Follow these steps to assign a spectrum group to an upstream port on a cable interface:

To enter the cable interface, use the interface cable command in Global Configuration mode, as shown

below:

RDN(config)#interface cable <slot>/< por t>

where: slot is the master DOCSIS module slot.

port is the cable interface number.

To apply a spectrum group to an upstream port, use the cable upstream spectrum-group command inInterface Configuration mode, as shown below:

RDN(config-if)#cable upstream <n> spectrum-group <group-name>

where: group-name is the exact group name applied to the upstream port.





Configuration

Use the show running-config command in Privileged EXEC mode to view the configuration of a spectrum

group that you created and applied to an upstream port, as shown below:

RDN#show running-config

Showing Spectrum Data



Showing Spectrum Data

Use the show interface cable upstream spectrum command in Privileged EXEC mode to view the noise power

level for the whole spectrum, as shown below:

RDN#show interface cable <slot>/< por t> upstream <n> spectrum

where: slot is the DOCSIS module number

port is the cable interface number

n is the upstream port number

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