DOCSIS 3.1 Upstream Signal Analysis - Keysight Upstream and Downstream DOCSIS 3.1 Devices April 2015 Steve Hall DOCSIS 3.1 Business Development Manager

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  • Testing Upstream and Downstream DOCSIS 3.1 Devices April 2015

    Steve Hall

    DOCSIS 3.1 Business Development Manager

  • Page

    Keysight

    Technologies 2015

    Agenda

    1. Decoding and demodulating a real downstream DOCSIS 3.1 signal and reporting key metrics

    such as MER and BER.

    2. Combining powerful trigger and recording techniques to detect, identify and repair issues that

    cause BER.

    3. Understanding the complexities of demodulating and measuring low frequency, small grant

    upstream signals.

    4. Generating in-channel and out-of-channel upstream and downstream DOCSIS 3.1 signals.

    2

  • Page

    Keysight

    Technologies 2015

    1. Decoding and demodulating a real downstream DOCSIS 3.1 signal and reporting key

    metrics such as MER and BER.

    2. Combining powerful trigger and recording techniques to detect, identify and repair issues that

    cause BER.

    3. Understanding the complexities of demodulating and measuring low frequency, small grant

    upstream signals.

    4. Generating in-channel and out-of-channel upstream and downstream DOCSIS 3.1 signals.

    3

    Agenda

  • Page

    Keysight

    Technologies 2015

    Physical Layer Link Channel (PLC) OFDM Channel Descriptor (OCD)

    Downstream Profile Descriptor (DPD) messages

    DOCSIS 3.1 Signal Format

    4

  • Page

    Keysight

    Technologies 2015

    NCP

    Fields

    Data

    Fields

    DOCSIS 3.1 Signal Format

    5

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    Automatic Demodulation of Downstream signals in VSA

    - New DOCSIS3.1 Downstream measurement option BHM for 89601B VSA

    (BHM)Key features:

    - Automatic setup for downstream configuration by demodulating and

    decoding:

    Physical Layer Link Channel (PLC)

    OFDM Channel Descriptor (OCD)

    Downstream Profile Descriptor (DPD) messages

    - Decode the NCP and locate the codewords for each profile

    - Demod the data for each profile - MER

    - Post-process MER & BER/PER measurements to accumulate over

    successive acquisition.

    Keysight

    Technologies 2015 6

  • Page

    Result Traces DOCSIS3.1 Downstream

    Step 1 detect and decode PLC Physical Layer Link Channel

    Step 2 detect and decode OCD OFDM Channel Descriptor

    (not necessarily sent every frame as per standard)

    Step 3 detect and decode DPD Downstream Profile Descriptor

    Keysight

    Technologies 2015 7

  • Page

    Result Traces DOCSIS3.1 Downstream

    Initial performance results

    Keysight

    Technologies 2015 8

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    Result Traces DOCSIS3.1 Downstream

    Report Profile Results

    Report NCP Results

    De

    sc

    rip

    tio

    n o

    f R

    es

    ult

    s

    Keysight

    Technologies 2015 9

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    Result Traces DOCSIS3.1 Downstream

    Keysight

    Technologies 2015 10

  • Page

    Result Traces DOCSIS3.1 Downstream

    Keysight

    Technologies 2015 11

  • Page

    MER Measurement

    Hardware Positioning

    $

    Max 160MHz

    Demod BW + RF Measurements

    Max 750 MHz

    Demod BW

    Max 510 MHz

    Demod BW + RF Measurements

    MER

    12

    Keysight

    Technologies 2015

  • Page

    Introducing the N9040B UXA Signal Analyzer

    8.4/13.6/26.5

    GHz

    Streamlined

    touch driven

    interface

    Full BW RTSA

    Up to 510

    MHz analysis

    BW

    89600 VSA &

    N9068C

    Phase Noise

    App

    Industry

    Leading

    Phase noise Keysight Technologies 2015 13

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    U5303A PCIe High-Speed

    Digitizer

    PCIe rack mount expansion

    chassis

    Desktop PC

    UXA N9040B Signal Analyzer

    Install 89600 VSA software on

    Windows 7 OS or on an

    external PC

    Keysight

    Technologies 2015

    89601B Vector Signal Analyzer

    OR

    Hardware Platforms: U5303A digitizer or X-Series Spectrum Analyzer

    http://www.magma.com/sites/default/files/EB3TX_5a.jpg

  • Page

    Hardware Platforms: U5303A digitizer and X-Series Spectrum Analyzer

    Preserve your X-Series investment!

    Combine the power of the PCIe Digitizer Modulation Measurements

    with the power of the PXA/UXA RF Measurememts.

    Personal Cpmputer

    Keysight

    Technologies 2015 15

  • Page

    Keysight

    Technologies 2015

    Agenda

    1. Decoding and demodulating a real downstream DOCSIS 3.1 signal and reporting key metrics

    such as MER and BER.

    2. Combining powerful trigger and recording techniques to detect, identify and repair issues

    that cause BER.

    3. Understanding the complexities of demodulating and measuring low frequency, small grant

    upstream signals.

    4. Generating in-channel and out-of-channel upstream and downstream DOCSIS 3.1 signals.

    16

  • Page

    Device Under

    Test

    DOCSIS

    Frame

    Generator

    M8190A

    To BER or not to BER:

    BER says everything is working nicely or that it is NOT!

    Hours of testing complete yet BER fails!

    How do you determine WHY your Bit Error Rate is failing?

    Golden Receiver Cable Modem

    CMTS (single ended)

    Optical Transport

    Amplifier

    BER

    What causes bit errors?

    Clipping?

    Noise?

    Compression?

    Interference?

    How and where do they show up other than in an

    accumulated over-time BER test?

    Rapid fire in-channel and adjacent-channel energy

    spikes?

    Increased unexpected signal amplitude?

    Spurious emissions?

    Reduced Adjacent Channel Power performance? Keysight

    Technologies 2015 17

  • Page

    How do DOWNSTREAM events manifest themselves?

    These events show up at various times and places

    and are distinguishable as perturbations in the

    frequency domain!

    By building a very flexible mask around the spectrum,

    these perturbations can be trapped, recorded,

    analyzed and subsequently questions answered! Keysight Technologies 2015 18

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    Keysight

    Technologies 2015

    The test steps

    Monitor Transient Spectral Behavior

    in Real Time

    Trigger on Transient Spectral Behavior in

    Real Time

    Record Transient Spectral Behavior Including Behavior

    Leading up to the event

    Determine if the Transient Spectral

    Behavior Caused Bit Errors

    Determine Root Cause and Repair

    Issue

    19

  • Page

    Keysight

    Technologies 2015

    The Tools: How are transients found?

    Real Time Spectrum Analysis

    Watch for the transient event

    20

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    Keysight

    Technologies 2015

    The Tools: How are transients found?

    Real Time Spectrum Analysis

    Watch for the transient event

    21

  • Page

    Keysight

    Technologies 2015

    Frequency Mask trigger

    Catches the transient

    The Tools: How are transients found?

    Real Time Spectrum Analysis

    Watch for the transient event

    22

  • Page

    Keysight

    Technologies 2015

    Set up frequency Mask Trgger in VSA

    The Tools: How are transients found?

    Real Time Spectrum Analysis + Vector Signal Analysis

    Watch for the transient event

    23

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    Keysight

    Technologies 2015

    Multiple Domain Insight

    Watch for the transient event

    24

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    Keysight

    Technologies 2015

    Note spectral behavior of transient event

    Multiple Domain Insight

    Watch for the transient event

    25

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    Keysight

    Technologies 2015

    Transient Event Impact on Constellation

    Impact on MER

    The Tools: How are transients found?

    26

  • Page

    DUT (Amplifier/Optical

    Transport or CMTS)

    M8190A (DOCSIS 3.1 Frame

    Generator)

    Real Time Spectrum

    Analyzer uses

    frequency Mask

    Trigger to detect

    unwanted energy in

    and around the

    desired signals.

    Vector Signal Analyzer begins recording triggered by a violation detected by

    the Real Time Spectrum Analyzer including a pre-trigger window

    Monitor Transient Spectral Behavior

    in Real Time

    Trigger on Transient Spectral Behavior in

    Real Time

    Record Transient Spectral Behavior Including Behavior

    Leading up to the event

    The test steps

    Keysight

    Technologies 2015 27

  • Page

    Study demodulation test results for the gap

    free recording to answer questions like:

    Was signal quality impacted buy the event

    that caused the recording to be triggered?

    Calculate and

    analyze BER

    results for the

    entire gap-free

    recorded frames in

    order to answer the

    question: Did THIS

    event cause bit

    errors?

    Determine if the Transient Spectral

    Behavior Caused Bit Errors

    Determine Root Cause and Repair

    Issue

    Keysight

    Technologies 2015 28

  • Page

    Automating the process

    Test Controller

    Create scripts to automate and record

    events.

    Monitor Transient Spectral Behavior

    in Real Time

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