Cable Proactive Network Monitoring as a Service

Bill Halvorsen – AS Solution Architect

PSOSPV-2002

• Introduction

• What is cable Proactive Network monitoring an Overview

• How does it work

• Full Band Capture: A spectrum analyzer in every home

• Demo of cPNM

• Conclusion

Agenda

Cable Proactive Network Maintenance as a Service (CPNMaaS)

• Lower OPEX by reducing call volume and truck rolls for field problems and repair issues.

Objective

• PNM provides proactive monitoring of the DOCSIS network. Allowing for repairs to be identified, located, prioritized and completed before service impact to customers.

Solution

• Improved operational efficiency, lowered OPEX cost, improved system performance and forward looking impact of new services like DOCSIS 3.1.

Result

CPNMaaS High Level Architecture

Delivery Process

CMTS

MSO Subscriber Database CPNM Portal

AS RF NCE

Failure Scenarios

Detailed Analysis

Optimization Levers

Cable Modem Full Spectrum Capture

OUTPUT – Recommendations

•Open Cases with NOC

•Track Issues open by CPNM

•Provide SME resource for field

•Assist in Delivering Optimization Service

Cable PNM Collector

DC

Customer Network

(SNMP, CLI)

Technician Portal FSC

cPNM overview

7

cPNM: The big picture

cPNM motivation

Which of the following do you have deployed more widely in your network?

(A)

Portable

test equipment

(B)

Handheld

test equipment

(C)

DOCSIS-based CPE

cPNM in cable networks: Overview

• Uses DOCSIS cable modems and set-tops as continuous “probes” throughout the network to identify and locate plant and subscriber drop problems

• Detect and locate faults in coax and actives before rolling trucks

• Perform trend analysis to predict future faults before they happen

• Improve network performance to higher levels for DOCSIS 3.1

• How? (1) Derive complex frequency response signatures from modem pre-equalization coefficients, (2) look for responses indicative of the presence of linear distortions, and (3) overlay modem location information on digitized outside plant maps.

cPNMaas Key Tenants

Turnkey ownership

NOC Business Assurance:

Improved effectiveness

Accelerated migrations,

and

Service assurance/experience

Focus People

Dedicated Team with vast Deployment Experience

End-to-End Responsibilityfrom Installation, Support, Maintenance and operation of the PNM service

Core Skills in Execution, Technology, and Process

Proactive Maintenance:

• Maintaining optimal

consumer

experience

• KPI/KQI measured

progress and

analytics

• Iterative

improvement,

learning and

adapting to smooth

preventative

maintenance

• Net positive

subscriber retention

• Faster Time to

Deployment

• Lesser Maintenance

Windows

• Right First Time

Approach

• Productivity and

Predictable Success

• Fact-based and

Evidence-based

Refinements

• Maintaining Security

Posture

How Does it Work?

12

What is equalization?• In a coaxial cable distribution network, higher frequencies are attenuated more than

lower frequencies as RF signals travel through the coax. This results in a tilted frequency response at the input to each amplifier.

• It is necessary to install a fixed-value plug-in equalizer at each amplifier. The equalizer has the opposite amplitude-versus-frequency response of the coaxial cable preceding the amplifier.

• The equalizer “cancels” the tilted frequency response, resulting in a flat amplitude-versus-frequency spectrum at the input to the amplifier’s internal gain stages.

50 MHz 870 MHz 50 MHz 870 MHz

50 MHz 870 MHz

Equalizer’s frequency response

Spectrum’s frequency responseafter equalization

What is an adaptive equalizer?

• Adaptive equalization performs a function similar to that of a cable amplifier’s equalizer, but rather than equalizing the entire 50-860 MHz downstream or 5-42 MHz upstream RF spectrum, it deals with just a single channel. Adaptive means the equalizer can change its characteristics as channel conditions change.

Graphic courtesy of Sunrise Telecom

What is an adaptive equalizer?

• An adaptive equalizer is a digital circuit that compensates for a digitally modulated signal’s in-channel complex frequency response impairments.

•Complex frequency response includes amplitude (or magnitude)-versus-frequency, and phase-versus-frequency.

• The adaptive equalizer uses sophisticated algorithms to derive coefficients for an equalizer solution “on the fly”—in effect, creating a digital filter with essentially the opposite complex frequency response of the impaired channel.

•At high SNR (ES/N0) the equalizer will synthesize the opposite response of the channel. At lower SNR doing so would cause noise enhancement, so a compromise solution is derived.

Pre-equalizer’s frequency

response

(inverse of channel response

“seen” by modem)

Post-equalized frequency

response

(response “seen” by CMTS)

Equalizer

Impedance MismatchesSource

(7 dB return loss)Load

(7 dB return loss)Transmission Medium

(1 dB attenuation)

+31 dBmVat time T0

+30 dBmVat time T1

+22 dBmV

+15 dBmV

+23 dBmV

+14 dBmV(-16 dBc)at time T2

+30

+25

+20

+15

+10

+5

Am

plit

ud

e(d

Bm

V)

Time (T)

Incident signal (T1) Echo (T2)

+14 dBmV

+30 dBmV

234 ns

100 ft23 20

Information that can be derived from coefficients (single modem)

Impulse coefficients (adaptive equalizer

graph)

In-channel frequency response

In-channel phase response

In-channel group delay

QAM constellation

Cable modem: CMTS:

cPNM: Locating a fault

• This example shows a 5T echo. That is, the time delay of the echo is approximately 5 symbol

periods.

• For a 6.4 MHz bandwidth upstream QAM signal, the symbol period is 1/(5.12 Msym/s) =

1.953E-7 second, or about 195 ns

• One symbol period can be converted to distance: (T/2) x VF, where T is the symbol period in

ns, and VF is the cable’s velocity factor: (195/2) x 0.87 = 85 feet, or 25.8 meters

• The distance for a 5T echo is 5 x 85 feet = 425 feet, or 130 meters

Distance from where?• Rule #1 - The distance is not measured from the modem

• Rule #2 - There must be at least two reflection points

• Rule #3 - The fault is one of the reflection points

~3.5T echo = 298 feetDistance between

splitter and

amplifier is 299

feet, or 91

meters

Full band capture: A spectrum analyzer in every home

21

cPNM spectrum analysis

• Quickly view the performance of the entire forward spectrum

• Complements DOCSIS coarse metrics (MER, FEC, etc.)

Why spectrum analysis?

• Evaluate frequency response of downstream RF spectrum

• Look for downstream ingress

Standing

waves

Resonant

peaking

Ingress

(e.g. LTE)FM radio

ingress

Suckouts Roll-off Filters Adjacency

Viewable frequency response impairments

Non-flat spectrum• Suck-outs/notches

• Tilt (and direction)

• Ripples/waves

• Roll-off

• Resonance/peaking

• Excessive leveling

• Adjacency/alignment

• Signal levels

• Pilot levels

• Missing QAM channels

• Audits

Interference/distortionOver-the-air ingress

FM

UHF

LTE

Foreign carriers

Wideband/transient noise

Group delay variation (filters, etc.)

Distortion/intermodulation

FBC example: Old/faulty plant

BEFORE

AFTER

FBC example: Damaged underground cable

BEFORE

AFTER

cPNM: A technician’s perspective

• It’s like having TDRs and spectrum analyzers distributed throughout the network (all DOCSIS devices) under centralized control

• Quicker identification of problem cause and fix strategy

• Customers don’t lose service during measurements

• Service calls can send techs to exactlywhere the problem is to quickly fix the issue

cPNM: An engineer’s perspective

• Uses DOCSIS CPE upstream pre-equalization coefficients to estimate channel impulse response

• Interpolation of pre-equalizer tap samples increases accuracy

• Correlation among modems and integration with GIS allows triangulation to locate source of impairment

cPNM: A manager’s perspective

• Raises the bar of our collective understanding of RF

• Exposes the problems being solved by adaptive equalizers

• Exposes end-of-line performance, creates transparency

• Potential to improve operational efficiency

Demo: cPNM

30

Conclusion

32

cPNM summary

• cPNM is a game changing technology that reduces OPEX and increases customer satisfaction

• cPNM technology will also be important in moving to higher order modulation in DOCSIS 3.1 since the plant must be even better maintained

• cPNM “hooks” have been included in the DOCSIS 3.1 specification

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