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DOCSIS 3.0

from a test and measurement point of view

Randy Francis Cable Networks Division

The HFC Pipe is Huge!

JDSU CONFIDENTIAL & PROPRIETARY INFORMATION

DOCSIS

3.0 Overview

     New Specifications – DOCSIS 3.0 Interface Specifications (released December 2006) – CPE equipment in development stages( Bronze, Silver, Full) Downstream data rates of

160 Mbps

or higher – Channel Bonding – 4 or more channels 1 x 256QAM => “up to” ~40Mbps 4 x 256QAM => “up to” ~160 Mbps Upstream data rates of

120 Mbps

or higher – Channel Bonding – 4 or more channels 1 x 64QAM => “up to” ~30Mbps 4 x 64QAM => “up to” ~120 Mbps Internet Protocol version 6 (IPv6) – IPv6 greatly expands the number of IP addresses • Expands IP address space from 32 bits to 128 bits • • IPv6 supports 3.4

×10 38 addresses; Colon-Hexadecimal Format

4923:2A1C:0DB8:04F3:AEB5:96F0:E08C:FFEC 100% backward compatible with DOCSIS 1.0/1.1/2.0

JDSU CONFIDENTIAL & PROPRIETARY INFORMATION

Maximum and (Maximum Usable)DownStream Speeds 4 Version

1.x

2.0

3.0 --------- 4 channel 3.0 --------- 8 channel

DOCSIS

42.88 (38) Mbit/s 42.88 (38) Mbit/s 171.52 (+152) Mbit/s +343.04 (+304) Mbit/s Downstream

EuroDOCSIS

JDSU CONFIDENTIAL & PROPRIETARY INFORMATION

Un-Bonded Upstream Data rates



Courtesy Motorola

JDSU CONFIDENTIAL & PROPRIETARY INFORMATION

Channel Requirements

 Combines down and upstream channels for added performance • • “Technically” could support 10 bonded down streams.

Plans are currently for 4 DS and up to 4 u/s channels to be bonded –

Do not have to be adjacent to each other – but must be within 60 MHz.

» “Bonded” in data layer – not Physical layer » Each DS channel remains a 6 MHz 256QAM » A DOCSIS 3.0 QAM can be a Primary or Secondary » Primaries carry all info needed for a CM to register » Secondary's do not have registration data – only payload » ALL down streams can be provisioned as primaries but there MUST be at least 1 primary. – Possible combinations of u/s and d/s – 2x1, 2x2, 3x1, 3x2, 3x3, 4x1, 4x2, 4x3, 4x4 – Each provides its own performance capability - and is scalable.

JDSU CONFIDENTIAL & PROPRIETARY INFORMATION

Security

    DOCSIS 1.0 had BPI ( Baseline Privacy Interface) – Did not hardware authenticate Cable Modems DOCSIS 1.1 and 2.0 have BPI+ – Digital Certificate based security – No more spoofing MAC addresses DOCSIS 3.0 adds more enhancements – and the specification is now named “Security”, or BPI/SEC BPI/SEC encrypts data flows between the CPE and the CMTS – BPI/BPI+ use 56 bit encryption – SEC uses 128 bit encryption

JDSU CONFIDENTIAL & PROPRIETARY INFORMATION

Pre-Equalization taps Better performance under adverse plant enviroment

   Docsis 1.1 has 8 tap u/s eq DOCSIS 2.0/3.0 uses u/s24 tap eq   Configured in response to the CMTS ranging request ( RNG-RSP) CMTS says give me a taste – CM responds with a burst CMTS analyzes response of the burst – and instructs CM on how to configure its EQ taps ( Equalizer Coefficients)

JDSU CONFIDENTIAL & PROPRIETARY INFORMATION

DOCSIS 3.0 Flavors

      BRONZE – Supports downstream bonding – Supports IPv6 SILVER – Supports upstream channel bonding – AES – Advanced Encryption Standard • More secure than DES – Data Encryption Standard – Support for IPDR • IP Detail Record • Allows “Consumption Based Billing” – Pay as you use FULL ( and you thought it would be gold?) – All of Bronze and Silver Applies to CMTS only – not CM’s CMs from Cisco, Moto, Ambit & Others are now available – 4x4 bonding only( Texas Instruments silicon – Broadcom announced 8x4 silicon (400Mbs DS/160 Mbs US) in January 2009 This is kinda important – you don’t want to have to upgrade twice. Think hard if 4x4 will be enough!

JDSU CONFIDENTIAL & PROPRIETARY INFORMATION

 

MSO Rollout of DOCSIS 3.0

Phase 1 – Prepare plant • • Physical layer upstream and downstream – Service turn-on Downstream Bonding – Adding additional Downstream carriers » Avoids Node Splitting » Provides load balancing – Relatively lower number of DOCSIS 3.0 customers on bonded channels – Capacity utilization on secondary/bonded downstreams more physical layer related • • Adding upstream channels – Avoids node splitting – Offers load balancing Limited by CMTS’s – Major CMTS vendors are only “Bronze” – Operators are deploying systems using same CMTS & CM vendors » Cisco & Cisco, Motorola & Motorola, Arris & Arris Phase 2 – Bonding upstream channels – Increasing number of DOCSIS 3.0 users on bonded channels • Higher capacity utilization and concerns

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MSO - Phase 2 Rollouts

  Phase 2: – Bonded upstreams • Major CMTS vendors aren’t planning on production release of bonded upstream support until late CY 2009 – Capacity ramping up – Deployment of DOCSIS 3.0 eMTAs for Voice service Tests covered by DOCSIS 3.0 solution – Upstream and downstream data-layer performance • • Throughput, packet loss, etc 100+ MB/s symmetrical – Breakdown bonded group performance • Isolation of channel issues

JDSU CONFIDENTIAL & PROPRIETARY INFORMATION

Testing during the Transition



What and How can we toast now?

JDSU CONFIDENTIAL & PROPRIETARY INFORMATION

Sorry – I meant “Test”

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Analog Integrity is Still Paramount, Supplemented by QAM Measurements

 Majority of “digital” issues involve basic analog maintenance of the RF plant – Levels, including network tilt, must be optimized beginning at headend – Carrier-to-noise and Hum on analog – Managing Hum has been shown to improve QAM carrier quality – MER on QAM channels – BER and DQI for intermittent impairments – Ingress and leakage management

JDSU CONFIDENTIAL & PROPRIETARY INFORMATION

“Back to the Basics” Troubleshooting

       Majority of problems are basic physical layer issues Do a visual inspection of cable, connectors and passives and replace as needed Check for proper grounding Tighten F connectors per your company’s installation policy – Be very careful not to over tighten connectors on CPE (TVs, VCRs, converters etc.) and crack or damage input RFI integrity Check forward and return RF levels, analog and digital Check for reverse ingress coming from home Most of the test strategy remains the same divide and conquer technique – bad here-good there-problem in between!

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What is Digital?



Source and Destination is digital data

– Assign unique patterns of 1’s and 0’s 

Transmission path is via an analog QAM carrier

– Choice of modulation is the one that optimizes bandwidth (data versus frequency ‘space’) and resiliency to noise

00 01 10 Generate Digital (modulate) 16

11 QAM Analog Carrier (“QAM Haystack”) JDSU CONFIDENTIAL & PROPRIETARY INFORMATION 00 01 10 Receive Digital (demodulate) 11

QAM Measurements



Spectrum & Digital Average Power Level



MER (Modulation Error Ratio )



Pre/Post FEC BER (Bit Error Ratio)



QAM Constellation Display



QAM “Ingress Under The Carrier”



QAM DQI (Digital Quality Index)



AGC Stress



Group Delay



In-Channel Frequency Response



Equalizer Stress

–

Items in red are really ANALOG impairments measured on a QAM channel 17

JDSU CONFIDENTIAL & PROPRIETARY INFORMATION

Hum



Low frequency amplitude modulation (<1 kHz) of a carrier when passing through an active or passive component



FCC states that Hum must be < 3%



Caused By

: – Power Supply Filter Failure – Bad Solder Connections – Corroded Connectors – Bad power supplies in amplifiers – Earth-loops on coax cables – Bad connection to ground – Earth-loops in headend, interfering with the TV modulators

JDSU CONFIDENTIAL & PROPRIETARY INFORMATION

Hum Modulation Characteristics

    

Diagnosis - if hum caused by . . .

–

60 Hz Component

– CAREFULLY!

- Check for bad ground connections –

120 Hz Component

Ripple (possible filter capacitor or diode failure) • - Check DC Power Supply For Can be customer equipment – old TV or VCR or radio ( remember them) power supply

Effect on analog TV picture:

slowly scroll up the picture one or two bars

Effect on Digital picture:

picture

Effect on DOCSIS ®

throughput

data:

digital tiling in the packet loss/slow

Effect on VoIP data:

JDSU CONFIDENTIAL & PROPRIETARY INFORMATION

Hum Mode is Easy and Non-Intrusive

 Tune to analog video carrier, press HUM key  Works on unscrambled analog video carriers only  In-service Hum measurement does not interfere with picture  Some meters have selectable 60Hz, 120Hz and <1,000Hz filters  HUM measurements can be expressed in percentage or dB

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AGC Stress

 Triggers alarm flag when meter AGC detects signal level change of > .5dB in 1 second of time.

  This small but rapid up and down change in level can cause problems with digital set tops boxes and CM’s.

Single channel can be caused by a problem with the QAM modulator  Flagging on multiple channels indicates a problem with the plant trunk/bridger AGC circuits

JDSU CONFIDENTIAL & PROPRIETARY INFORMATION

Testing the Home for Ingress Contribution

7 dB TAP Return Equalizer Drop Cable Disconnect drop from tap and check for ingress coming from customer’s home wiring OLDER TV SET WIRELESS LAPTOP If ingress is detected, scan spectrum at ground block for ingress 22

GROUND BLOCK DIGITAL SET-TOP COMPUTOR 2-Way Amplifier High Pass Filter

ETHERNET

3-Way Splitter

eMTA-CABLE MODEM

INGRESS SPECTRUM MEASUREMENTS JDSU CONFIDENTIAL & PROPRIETARY INFORMATION VoIP ONLINE GAMING

There are Many Possible Sources of Interference

23 Off-Air Broadcast

•

AM Radio Station

•

FM Radio Station

•

TV Station

•

Two-way Radio Transmitters

•

Citizens Band (CB)

•

Amateur (Ham)

•

Taxi

•

Police

•

Business

•

Airport/Aircraft

•

Paging Transmitters FEDERAL COMMUNICATIONS COMMISSION

Electrical Devices

•

Doorbell transformers

•

Toaster Ovens

•

Electric Blankets

•

Ultrasonic pest controls (bug zappers)

•

Fans

•

Refrigerators

•

Heating pads

•

Light dimmers

•

Touch controlled lamps

•

Fluorescent lights

•

Aquarium or waterbed heaters

•

Furnace controls

•

Computers and video games

•

Neon signs

•

Power company electrical equipment

•

Alarm systems

•

Electric fences

•

Loose fuses

•

Sewing machines

•

Hair dryers

•

Electric toys

•

Calculators

•

Cash registers

•

Lightning arresters

•

Electric drills, saws, grinders, and other power tools

•

Air conditioners

•

TV/radio booster amplifiers

•

TV sets

•

Automobile ignition noise

•

Sun lamps

•

Smoke detectors JDSU CONFIDENTIAL & PROPRIETARY INFORMATION

Typical Ingress Problem Areas

   Taps – Most ingress comes from houses with tap values of 17 dB or less House Wiring – Drop Cable & F Connectors contribute approximately ~95% of system ingress problems Amplifiers, hard line cable and the rest of the system are a small percentage of the problem if a proper leakage maintenance program is performed.

JDSU CONFIDENTIAL & PROPRIETARY INFORMATION

“Reverse Spectrum” Install Test



View return spectrum (5 to 42 MHz) and FM band (88 to 108 MHz)



Select peak hold and wait for a few minutes



Re-scan spectrum to confirm that you’ve fixed the ingress problem in the home 25

JDSU CONFIDENTIAL & PROPRIETARY INFORMATION

Taps - Probe the Seizure Screws for Ingress & CPD

If the problem is at the FWD Output of tap, continue on towards end of line If the problem is at the FWD Input and not the FWD Output, then the problem is likely from one of the drops 26

Return Path Forward Path Disconnect one drop at a time to determine the point of entry JDSU CONFIDENTIAL & PROPRIETARY INFORMATION

Taps are made up of a Directional Coupler and Splitters

10.393 dBmV -10 -20 -30 -40 40 In-Band Power 10 0 30 20 -50 -60 Span: 40.000 M Hz RBW: 300 KHz 20 10 40 In-Band Power 30 0 -10 -20 -30 -40 -50 -60 Span: 40.000 M Hz RBW: 300 KHz 8.632 dBmV Center: 25.000 M Hz VBW: 100 KHz Dwell: 400 µS

Probe the seizure screws for ingress

Center: 25.000 M Hz VBW: 100 KHz Dwell: 400 µS

Seizure screw probe 27

Disconnect one drop at a time to determine the point of entry 4 Port Tap JDSU CONFIDENTIAL & PROPRIETARY INFORMATION

Equalizer Stress

    

Digital demodulation receivers utilize adaptive equalizers to negate the effects of signals arriving other than the desired signal. Signals can arrive ahead of or after the desired signal. In a cable system, the majority of signals are reflections and micro-reflections that arrive after the desired signal.

Cable modems and digital set top boxes must be able to handle pre and post signals at levels defined by DVB standards. If the equalizer is pushed beyond those limits, errors will occur.

By using the Velocity of Propagation, the distance to the source of the reflection can sometimes be located. If the reflections occur before the next upstream amplifier, they are simply amplified and passed downstream thereby eliminating the ability to perform fault detection based on reflection time.

Equalizer stress is used more as a figure of merit for the margin available to the set top box or cable modem.

JDSU CONFIDENTIAL & PROPRIETARY INFORMATION

Equalizer Stress

Signal arriving about 2usec after desired carrier

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Micro reflections

Fault here….

C 14 BUT..it has to go thru isolation of directional coupler ….and tap loss Will we see it at drop?

A B Causes energy to reflect back…..

Level 35dbmv 35dBmv Fault Minor(15 dbRL) After cable loss, Coupler isolation and tap loss (20)-(4)-(25) (14)=(-23dBmv) Short/Open (0 RL) (35)-(4)-(25) (14)=(-8 dBmv)

JDSU CONFIDENTIAL & PROPRIETARY INFORMATION

Micro reflections

Fault here….

B Causes energy to reflect back…..

But its easy to see at non directional or resistive test points

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In Channel Frequency Response

In-Channel Frequency response is amplitude ripple. This means that signals at one frequency are attenuated relative to signals at another frequency. For downstream digital carriers DOCSIS 1.0 specifies a max ripple of 0.5dB in 6MHz. DOCSIS 1.1 has relaxed this specification to 3.0dB in 6MHz.

JDSU CONFIDENTIAL & PROPRIETARY INFORMATION

BER – yet again

 A 256QAM channel transmits at a symbol rate of 5M symbols per second  Bit rate = 8 bits per symbol X 5M symbol per second =40M bits per second  Error Incident = Bit rate X BER = Errors Per Second

BER Error Frequency Error Incident

10 -12 10 -11 10 -10 10 -

10 -8 10 -

10 -

10 -5 10 -4 10 -3 1 in 1 Trillion bits 1 in 100 Billion bits 1 in 10 Billion bits 1 in 1 Billion bits 1 in 100 Million bits 1 in 10 Million bits 1 in 1 Million bits 1 in 10 Thousand Bits 1 in 1 Thousand bits 25000 secs between errs (6.94 hrs) 2500 secs between errs (41.67 mins) 250 secs between errs (4.167 mins) 25 seconds between errors 2.5 seconds between errors 4 errors per second 40 errors per second 1 in 100 Thousand bits 400 errors per second 4000 errors per second 40000 errors per second © 2009 JDSU. All rights reserved.

JDSU CONFIDENTIAL & PROPRIETARY INFORMATION

Lets simplify Pre and Post FEC

  Imagine some ping pong balls How many balls can you play catch with…….

And not drop one?

JDSU CONFIDENTIAL & PROPRIETARY INFORMATION

BER and intermittent’s…..

  Even though digital services (and VoIP) work at MERs of 32, and pre BER of E 7…….THINK…  If you found the cause of that less than normal MER….or improved BER from E-7 to E-8……  Do you think that might have an impact on an intermittent issue?

Lets imagine some ping-pong balls

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Why fix -8 and -7 Pre-FEC BER?

     You decide to go Bungee Jumping BungJee Jumpee Co says they use 100% more bungee strands than your weight needs….for safety!

You need 50 strands for your weight, so they tell you they will use 100.

When they go to put the bungee on your leg you notice a lot of broken strands…when you point this out, they say..

Not to worry….you only need 50, right?

ARE YOU JUMPING???

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Constellation – a few words

 Constellation is Graphic View of MER – But captures bursty impairments better  A constellation displaying significant noise  Dots are spread out indicating high noise and most likely significant errors – An error occurs when a dot is plotted across a boundary and is placed in the wrong location  Meter will not lock if too much noise present Dots are spread out showing error

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Gain Compression

 If the outer dots are pulled into the center while the middle ones are not affected, the signal has gain compression  Gain compression can be caused by IF and RF amplifiers and filters, up/down converters, modulators, etc Outer edges pulled in

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Phase Noise

   Display appears to rotate at the extremes HE down/up converters can cause phase noise Random phase errors cause decreased transmission margin   Caused by transmitter symbol clock jitter Bad LO in meter can cause phase noise Constellation Rotation Rotation

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Coherent Interference

 If the accumulation looks like a “donut”, the problem is coherent interference – CTB, CSO, spurs and ingress  Sometimes only a couple dots will be misplaced – This is often laser clipping or sweep interference – Remember I told you about sweep insertion points?

Circular “donuts”

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BUT…….

  Constellation still doesn’t tell the whole story Constellation is ‘Sampled’ – For each point ( Symbol ) plotted, there are 1000’s that are not.

– So transient intermittents can still be missed.

 DQI is a method of showing transients that BER/Consellation views can still miss – Accesses I/Q data before the Constellation sampler

JDSU CONFIDENTIAL & PROPRIETARY INFORMATION

Digital Analysis Tools - DQI

Index from 0 to 10 simplifies reading Derived from Raw I-Q data

DQI responds faster and gives the tech extra margin versus traditional measurements Momentary events are easily seen in the historical graph

JDSU CONFIDENTIAL & PROPRIETARY INFORMATION

Current Support of Phase 1: Upstream Testing

 Most field meters can test upstream signal quality – Range, Packet Loss, VoIP Check, Throughput   Isolate Packet Loss issues on the RF Plant from the IP Plant. Goal is to have 0% pkt loss Pkt loss on CMTS loop is often due to return path issues PacketLoss and VoIP Check are powerful tools to troubleshoot upstream/downstream BER issues Upstream QAM generator used out of band with Headend analyzer – Troubleshoot degraded node performance and find problems in plant.

JDSU CONFIDENTIAL & PROPRIETARY INFORMATION

So what will 3.0 test screens look like?

 Maybe something like this:

JDSU CONFIDENTIAL & PROPRIETARY INFORMATION

Thank you –

Randy Francis JDSU

Title Here

Transcript Title Here

DOCSIS 3.0

The HFC Pipe is Huge!

DOCSIS

3.0 Overview

Un-Bonded Upstream Data rates

Channel Requirements

Security

DOCSIS 3.0 Flavors

MSO Rollout of DOCSIS 3.0

MSO - Phase 2 Rollouts

Testing during the Transition

What and How can we toast now?

Sorry – I meant “Test”

“Back to the Basics” Troubleshooting

What is Digital?

QAM Measurements

Hum

Hum Modulation Characteristics

Hum Mode is Easy and Non-Intrusive

AGC Stress

Testing the Home for Ingress Contribution

There are Many Possible Sources of Interference

Typical Ingress Problem Areas

“Reverse Spectrum” Install Test

Taps - Probe the Seizure Screws for Ingress & CPD

Equalizer Stress

Equalizer Stress

Micro reflections

Micro reflections

In Channel Frequency Response

BER – yet again

Lets simplify Pre and Post FEC

BER and intermittent’s…..

Why fix -8 and -7 Pre-FEC BER?

ARE YOU JUMPING???

Constellation – a few words

Gain Compression

Phase Noise

Coherent Interference

BUT…….

Digital Analysis Tools - DQI

So what will 3.0 test screens look like?

Thank you –

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