Docsis 3 0 Demystification Deployment Testing (2)

Transcript

Technical Training Seminar on “Practical Field Testing DOCSIS 3.0” for CCTA Member Companies August 24, 25 and 26, 2010 San Juan, Puerto Rico Mario Sebastiani Tony Holmes Practical Field Testing – DOCSIS 3.0 Overview ƒ ƒ ƒ ƒ Quick discussion of DOCSIS 3.0 importance Impact of D3 on testing D3 deployment and preventive maintenance Practical methods for testing D3 signal transmission quality ƒ Troubleshooting the Return Path ƒ Monitoring the Return Path Practical Field Testing – DOCSIS 3.0 DOCSIS 3.0 ƒ Higher Data Rates – Channel Bonding ƒ Dynamic Load Balancing – Dynamic Channel Change & Per Packet Load Balancing ƒ Better Bandwidth Utilization – Source Specific Multicast – Multicast Header Suppression ƒ High Quality IP Video – Multicast Quality of Service ƒ More IP Addresses When You Need Them – IPv4 and IPv6 Support Practical Field Testing – DOCSIS 3.0 DOCSIS 3.0 ƒ Enhanced Security – 128 bit AES encryption (Advanced Encryption Standard) – Increased Cable Modem provisioning process security ƒ Option to Increase Upstream Bandwidth – Option for 5-85 MHz upstream support ƒ Powerful Reporting to Manage Traffic – Cable modem diagnostic log – Enhanced signal quality monitoring – Service statistics reporting - IPDR Practical Field Testing – DOCSIS 3.0 Impact on Testing ƒ Need higher reliability and performance, while minimizing operating expense – Increase efficiency and productivity ƒ DOCSIS 3.0 – Group of signals (bonded) with interrelated relevance ƒ Physical transmission is same as DOCSIS 2.0 ƒ IP related measurements require embedded DOCSIS 3.0 modem Practical Field Testing – DOCSIS 3.0 Higher Data Rates ƒ Upstream Capacity with 6.4MHz & 64QAM – Two channels, 60 Mbps – Three channels, 90 Mbps – Four channels, 120 Mbps ƒ Downstream Capacity with 6MHz & 256QAM – – – – Two channels, 80 Mbps Three channels, 120 Mbps Four channels, 160 Mbps Eight channels, 320 Mbps Practical Field Testing – DOCSIS 3.0 Channel Bonding ƒ Example: Practical Field Testing – DOCSIS 3.0 “Primary” Channels ƒ One Channel in Group carries timing info for whole group ƒ Each Channel in Group carries its own timing information Practical Field Testing – DOCSIS 3.0 Proactive Testing Makes Sense ƒ Fewer emergencies, lower operating expense, higher customer satisfaction ƒ “Old school” plant performance testing – Sweep – Leakage – End-of-line testing Practical Field Testing – DOCSIS 3.0 Plant Qualification Checklist ƒ Headend RF alignment ƒ Downstream 256-QAM testing and qualification ƒ Upstream 64-QAM testing and qualification – – – – Avoid frequencies near the roll-off or band edges Avoid frequencies susceptible to ingress, if possible Control ingress, noise, CPD and laser clipping Tighten RF leakage thresholds Practical Field Testing – DOCSIS 3.0 DOCSIS 3.0 Checklist ƒ Test equipment – DOCSIS 3.0 field test meter ƒ 64-QAM signal source ƒ Upgrade or purchase new QAM Analyzers Practical Field Testing – DOCSIS 3.0 Preventive Maintenance Checklist ƒ Do complete system sweep every 12-18 months (all actives) ƒ End-of-line digital testing (MER & BER) ƒ Leakage Testing ƒ Return Path Monitoring ƒ Daily reports (use as historical references) Practical Field Testing – DOCSIS 3.0 Installation Testing Pays Off ƒ Comprehensive with minimal impact on Tech time – Establishes baseline – “Certification” leads to higher quality and reliability ƒ Level scan, MER, BER, cable modem statistics, ingress, leakage Practical Field Testing – DOCSIS 3.0 Preparation Testing ƒ Upstream needs special attention ƒ Node certification: return path spectrum – Extended period of testing required ƒ Speed is of the essence ƒ Spectrum suitability analysis – DISP, ADISP Practical Field Testing – DOCSIS 3.0 Post-Deployment Testing ƒ Installation – Cable modem statistics – Throughput Practical Field Testing – DOCSIS 3.0 Test Automation ƒ Efficient, error-free testing ƒ DOCSIS 3.0 environment autotest includes: – Channels in a group – Set of tests to be performed on each channel – Performance limits to analyze test result Practical Field Testing – DOCSIS 3.0 Typical D3 Autotest ƒ Consider sequence to minimize ranging and registering ƒ Test relevant parameters Practical Field Testing – DOCSIS 3.0 Typical Autotest for D3 ƒ Once the autotest is built and loaded into the meter: ƒ Tech pushes one button and runs specific tests on specified channels ƒ Alerts tech to failures right away Practical Field Testing – DOCSIS 3.0 Typical Autotest for D3 ƒ Tech can then retrieve and view supporting test details, or save files for uploading to server. Practical Field Testing – DOCSIS 3.0 D3 Autotest Results Practical Field Testing – DOCSIS 3.0 D3 Autotest Results Practical Field Testing – DOCSIS 3.0 D3 Autotest Results Practical Field Testing – DOCSIS 3.0 D3 Test Macro Summary Report ƒ Results may be retained, displayed in supporting software Practical Field Testing – DOCSIS 3.0 Transmission System Troubleshooting Tools ƒ QAM Analyzer – in the field and in the headend/hub site ƒ Return Path Monitoring Equipment ƒ Probe – bi-directional ƒ Leakage System Practical Field Testing – DOCSIS 3.0 Plant Performance Testing ƒ Forward and reverse sweep ƒ Upstream QAM analysis from EOL ƒ Leakage (tightened threshold?) Practical Field Testing – DOCSIS 3.0 MER ƒ MER degradation – does not effect picture quality until failure ƒ MER accounts for – amplitude noise – phase noise Practical Field Testing – DOCSIS 3.0 Troubleshooting Low MER ƒ Is it noise or interference? – Noise may indicate an amplifier or other active component failure – Interference may indicate: ƒ Distortion – active component ƒ Ingress – leakage (stray RF in means RF straying out) ƒ Spectrum analysis helps – Use error vector spectrum to see within the channel range (under the haystack) ƒ Constellation analysis (tell-tale shapes – donuts, clouds, etc.) Practical Field Testing – DOCSIS 3.0 Error Vector Spectrum ƒ To view the noise floor under QAM the carrier needs to be removed Practical Field Testing – DOCSIS 3.0 Troubleshooting High BER ƒ Is MER low? (see last advice) ƒ Pre-FEC or Post-FEC, measure of severity ƒ Are bit errors continuous or sporadic? – Look at graph of errors over time – Can time signature be determined? (may give clue to cause) ƒ Is BER failure frequency (channel) specific and sporadic? – Look at error vector spectrum over time Practical Field Testing – DOCSIS 3.0 Impulse BER ƒ BER – Corrupted bits/total bits received ƒ Shows BER before and after FEC ƒ Errored Seconds – The number of seconds with at least one corrected codeword ƒ Severely Errored Seconds – The number of seconds with at least one uncorrectable codeword ƒ Valuable troubleshooting tool – Whenever there are errors use this screen to divide and conquer Practical Field Testing – DOCSIS 3.0 BER ƒ Bit Error Rate is the number of bits in error divided by the total number of bits in the data transmission ƒ Pre BER – System Margin Practical Field Testing – DOCSIS 3.0 Forward Error Correction ƒ FEC – Corrects errors to a point Pre FEC BER (Before Correction) Post FEC BER (After Correction) Practical Field Testing – DOCSIS 3.0 Troubleshooting the Return Path Practical Field Testing – DOCSIS 3.0 Components of The Guardian II System ƒ Guardian II integrated server package ƒ 9581 SST R4 Headend unit ƒ 8310 RSA ƒ Viewer II client software for NOC operations ƒ ADIA historical analysis suite ƒ SST Configure software ƒ Field units: – 860 DSPi – RSVP2 Practical Field Testing – DOCSIS 3.0 Troubleshooting Ingress ƒ Compare local test point spectrum to headend/hub spectrum ƒ Use I-stop probe to load local test point and see if headend spectrum drops – If it drops the problem is farther down the line – If it doesn’t the problem is closer to the headend/hub – Low-pass filter is also recommended Practical Field Testing – DOCSIS 3.0 Reverse Ingress ƒ Top displays Local ƒ Bottom displays headend ƒ Move your location until you find the source of the ingress Practical Field Testing – DOCSIS 3.0 Return Sweep Mode ƒ Displays – Gain/Tilt – Frequency Response – Headend Ingress levels ƒ Gain Information – Difference between Headend nominal and sweep carrier level ƒ Tilt Information – Difference between low and high pilots carrier levels ƒ Pads and Equalizers – Gain/Tilt values of 0 are perfect – Values other than 0 indicate the change in Pad/EQ necessary to bring the system into alignment Practical Field Testing – DOCSIS 3.0 Return Sweep Mode ƒ Frequency Response Trace – Plots received (Headend) level for each sweep carrier – Scale per Division 2 dB – Ideal Trace is a flat line ƒ Impairments to frequency response – Damaged Cable – Damaged actives or passives – High Ingress Levels Practical Field Testing – DOCSIS 3.0 RSVP Installation Verification ƒ Continuity Test – Talks directly to the 9581 SST headend unit ƒ Measures the C/N ƒ Displays the test Results ƒ Shows a Pass or Fail Practical Field Testing – DOCSIS 3.0 Troubleshooting transients in upstream signal bands ƒ Test feature uses limits to remove legitimate traffic from the spectrum view ƒ Removes the haystack and reveals the needle ƒ Provides insight in monitoring as well as troubleshooting ƒ Spectrum acquisition speed reveals fast transients Practical Field Testing – DOCSIS 3.0 In-channel Upstream Spectrum Analysis ƒ Return spectrum is getting crowded, making inspection of spectrum problems difficult ƒ Test mode can be used to see the ingress or distortion “underneath” an upstream cable modem carrier, VoIP carrier, or any bursty signal ƒ Troubleshooting made easy – Divide & Conquer – Source typically a home Practical Field Testing – DOCSIS 3.0 Laser Clipping ƒ Typically caused by input overload, operating in non-linear transfer range ƒ Where it shows up: – Return path spectrum, distortion products above max frequency range – Constellation – intermittent compression – Impulse BER – bit errors due to clipping Practical Field Testing – DOCSIS 3.0 Understanding the Spectrum Analyzer ƒ ƒ ƒ ƒ ƒ ƒ ƒ Reference / Input Detector Sweep Time RBW dB/Div Frequency Tuning Max/Min Hold Practical Field Testing – DOCSIS 3.0 Is It System Noise? l Internal spectrum analyzer noise may be too high to allow system noise measurement ∗ use the disconnect test Practical Field Testing – DOCSIS 3.0 The Disconnect Test l l l If > 10 dB drop, no corrections needed 10 9 If > 3 dB drop, correct by using the graph below 8 If < 3 dB drop, use a 20-30 dB gain, <10 dB noise figure preamplifier 7 6 5 4 Noise-Near-Noise Correction (dB) 3 2 1 0 0 1 2 3 4 5 6 7 8 Noise Drop For Disconnect Test, dB 9 10 Practical Field Testing – DOCSIS 3.0 Correcting Analyzer for Noise-Near-Noise System Noise Analyzer Noise 0.5 dB 10.0 dB 1.2 dB 6.0 dB 3.0 dB 3.0 dB 1.0 dB (a) Disconnect Test 6.9 dB (b) Correction Values Practical Field Testing – DOCSIS 3.0 Ingress Mitigation Test ƒ This is a test where you can quickly check the drop and home wiring for ingress ƒ Set Ref level so as to not over-load the meter ƒ Detector set for averaging ƒ RBW at 300 KHz ƒ 10 db/div ƒ Spectrum 5-108 MHz ƒ Use peak hold Practical Field Testing – DOCSIS 3.0 Ingress Mitigation Test ƒ What you should see is NOTHING! ƒ Just the noise floor Practical Field Testing – DOCSIS 3.0 Ingress Mitigation Test ƒ Look for ingress by using the “Peak Hold” function ƒ Identify the problem by working back towards the house Practical Field Testing – DOCSIS 3.0 Laser Clipping Return Path Spectrum ƒ Note the products above 42 MHz Practical Field Testing – DOCSIS 3.0 Monitoring the Return Practical Field Testing – DOCSIS 3.0 Viewer II User Interface ƒ Components – – – – Status Tree Incident Log Alarm History Spectrum Display Practical Field Testing – DOCSIS 3.0 Node Status Tree ƒ Geography – Groups nodes by ƒ City ƒ Headend ƒ Hubsite ƒ Services – Groups nodes by ƒ CMTS ƒ Blade Practical Field Testing – DOCSIS 3.0 ADIA Historical Analysis Server ƒ Collects spectral information from the 9581 SST headend units – Spectral information contains Max/Min/Avg ingress information collected in 9581 SST and compressed into 15 minute summaries – Return Path performance information against user specified limits ƒ Provides database storage for 3000 nodes over a one year time period Practical Field Testing – DOCSIS 3.0 Spectral History ƒ Review ingress signature of selected node – Over user specified time period – Max/Min/Avg traces – With live spectral overlay Practical Field Testing – DOCSIS 3.0 Spectral History ƒ Retrieve Spectral History – Both spectral and time based views – Evaluate the severity and duration of ingress related events – View the waterfall graph Practical Field Testing – DOCSIS 3.0 ADIA Node Service Report Practical Field Testing – DOCSIS 3.0 Return Path Reports ƒ Worst Offenders List – Provides summary of worst offending nodes by alarm level over specified time period ƒ Node Alarm Summary – Allows user to view alarms over specified time frame ƒ Alarm History Over Time – Allows user to view alarm history over a time period summarized by hour, day, or month Practical Field Testing – DOCSIS 3.0 Demonstration Impairments from : •Forward Path Ingress •Return Path Ingress Practical Field Testing – DOCSIS 3.0 Review ƒ DOCSIS 3.0 improves competitive position, and revenue ƒ Reliability is crucial, testing helps ƒ Practical preparation for D3 deployment and preventive maintenance check lists ƒ Practical D3 signal transmission quality tests ƒ Tests for troubleshooting ƒ Test equipment D3 evolution Practical Field Testing – DOCSIS 3.0 Response to Your Questions!!!! Practical Field Testing – DOCSIS Technical Training Presentation – CCTA 2009 3.0 Thank you-Gracias-Merci-Masha Danki… Trilithic Applications Engineering [email protected] Tel: 800-344-2412 ---------------------------------------------------------------------- Incospec Communications Inc. Your Value Adder Trilithic Re-Seller for the Caribbean Mario Sebastiani ([email protected]) Bernard How ([email protected])