Presentation is loading. Please wait.

Presentation is loading. Please wait.

Triple-Play Service Testing Carlene Gardner Strategic Marketing Manager JDSU Cable Networks Division For CCTA Training, San Juan PR, August 26, 2009.

Similar presentations


Presentation on theme: "Triple-Play Service Testing Carlene Gardner Strategic Marketing Manager JDSU Cable Networks Division For CCTA Training, San Juan PR, August 26, 2009."— Presentation transcript:

1 Triple-Play Service Testing Carlene Gardner Strategic Marketing Manager JDSU Cable Networks Division For CCTA Training, San Juan PR, August 26, 2009

2 © 2009 JDSU. All rights reserved.JDSU CONFIDENTIAL & PROPRIETARY INFORMATION2 Outline Problems in reverse path –What to look for to check carrier health –What causes performance to degrade DOCSIS testing –Recap of process to get online –Tips for testing to check where the problem is VoIP testing –Specific parameters for voice service –Why it is different Future services

3 Upstream Test Parameters

4 © 2009 JDSU. All rights reserved.JDSU CONFIDENTIAL & PROPRIETARY INFORMATION4 Metric: Carrier to Noise, Signal to Noise Noise

5 © 2009 JDSU. All rights reserved.JDSU CONFIDENTIAL & PROPRIETARY INFORMATION5 Metric: Carrier to Noise, Signal to Noise C/N and SNR, versus the noise floor, are somewhat predictive of BER and MER

6 © 2009 JDSU. All rights reserved.JDSU CONFIDENTIAL & PROPRIETARY INFORMATION6 Metric: MER Modulation Error Ratio (MER) on downstream QAM carrier is similar to S/N or C/N MER on upstream QAMs is similar to SNR read at CMTS MER determines how much margin the system has before failure

7 © 2009 JDSU. All rights reserved.JDSU CONFIDENTIAL & PROPRIETARY INFORMATION7 Metric: MER MER math RMS error magnitude Average symbol magnitude Indicates how close symbols are to ideal point MER(dB) = 10 x log RMS error magnitude average symbol magnitude Upstream channel fails if MER is not better than –QPSK: 18 dB MER –16 QAM: 24 dB MER –64 QAM: 27 dB MER

8 © 2009 JDSU. All rights reserved.JDSU CONFIDENTIAL & PROPRIETARY INFORMATION8 Metric: MER of constellation

9 © 2009 JDSU. All rights reserved.JDSU CONFIDENTIAL & PROPRIETARY INFORMATION9 Metric: MER degradation due to noise Symbols cannot reach ideal point due to noise Ideal points

10 © 2009 JDSU. All rights reserved.JDSU CONFIDENTIAL & PROPRIETARY INFORMATION10 What Causes MER and BER to degrade? Noise Ingress in Upstream Cause: –Often originating from subscribers homes, loose RF connectors, or faulty coax cable –Upstream noise is worse at headend due to funneling –A little bit of noise from many locations becomes a lot of noise at the headend Effect –When noise ingress gets too high, data symbols start falling outside their constellation boundaries –The CMTS can no longer correctly determine good data from bad –FEC is no longer able to correct corrupted data packets –The CMTS discards packets with too much data corruption –Web & traffic will re-transmit and may eventually get through –VoIP traffic is lost forever!

11 © 2009 JDSU. All rights reserved.JDSU CONFIDENTIAL & PROPRIETARY INFORMATION11 What Causes MER and BER to degrade? Note that the higher noise floor causes the MER measurement To degrade Noise

12 © 2009 JDSU. All rights reserved.JDSU CONFIDENTIAL & PROPRIETARY INFORMATION12 What Causes MER and BER to degrade? Coherent Ingress Cause –Coherent Ingress are carrier waves or other constant carrier signals that exist in the HFC network –Ingress: Often originating from subscribers homes, loose RF connectors, or faulty coax cable –Internally-generated impairment: Common Path Distortion (CPD) Effect –Within a DOCSIS upstream channel, can cause intermittent, complete data loss or cause a complete DOCSIS outage –Subscribers may complain about a problem that comes and goes 24x7 monitoring of ingress is the only way to confidently identify intermittent ingress problems

13 © 2009 JDSU. All rights reserved.JDSU CONFIDENTIAL & PROPRIETARY INFORMATION13 What Causes MER and BER to degrade? Compression – Laser / RF Amplifier Cause –Excessive input levels into an active device causing the laser or amplifier to clip or not be able to transmit the highest amplitude voltage signals –Not rebalancing upstream devices after a change such as adding another DOCSIS channel Effect –Laser or amplifier clipping causes data loss because the highest amplitude symbols (bits) are pushed into other symbol decision boundaries –Data loss can be continuous or sporadic depending upon system and device conditions –Web traffic can be re-transmitted, but VoIP traffic is permanently lost

14 © 2009 JDSU. All rights reserved.JDSU CONFIDENTIAL & PROPRIETARY INFORMATION14 What Causes MER and BER to degrade? Group Delay Cause –Linear changes in phase of a signal –Inherent difficulty of maintaining even speed of propagation through multiple devices, long amplifier cascades –Group delay can also occur due to amplitude changes throughout the upstream band Effect –Frequencies propagate at different speeds through the HFC plant –Group delay affects cable modem signal quality and thus MER –If group delay is bad enough, the CMTS will be unable to recover the transmitted signal and data will be lost (<200 nsec/MHz is spec) –Data and VoIP communications will be impacted or lost completely

15 DOCSIS Testing

16 © 2009 JDSU. All rights reserved.JDSU CONFIDENTIAL & PROPRIETARY INFORMATION16 DOCSIS Test – Initialization of a Modem Scan and synchronize to downstream Obtain upstream parameters Range Send device class Establish IP connectivity Establish time of day Get operational parameters Ranging Registration

17 © 2009 JDSU. All rights reserved.JDSU CONFIDENTIAL & PROPRIETARY INFORMATION17 Qualify the Drop Verify receive level at cable modem MER shows that downstream is clean and clear with margin BER shows that downstream is clean and clear of impulse noise Upstream is properly aligned and CMTS has ideal receive level Packet Loss Throughput

18 © 2009 JDSU. All rights reserved.JDSU CONFIDENTIAL & PROPRIETARY INFORMATION18 Registration Full list of registration addresses, Service Identifier (SID) and config file assigned Error messages detail where a failed test halted, can help locate source of problem

19 © 2009 JDSU. All rights reserved.JDSU CONFIDENTIAL & PROPRIETARY INFORMATION19 IP or RF?

20 © 2009 JDSU. All rights reserved.JDSU CONFIDENTIAL & PROPRIETARY INFORMATION20 IP Impairments Traffic Congestion –CMTS Over-utilization –Switch / Router Over-utilization –Viruses, Worms or just General Killer Apps Routing Errors –Cable Modem routes –MTA routes –IP Gateways Provisioning Issues –Subnet Rules –Configuration Files such as TFTP Files –SNMP –BPI & PacketCable Certificates

21 VoIP Testing

22 © 2009 JDSU. All rights reserved.JDSU CONFIDENTIAL & PROPRIETARY INFORMATION22 VoIP – Bullet Train Analogy Ideal World: –Packets like train Cars through a station – 1 at a time, evenly spaced, and Fast

23 © 2009 JDSU. All rights reserved.JDSU CONFIDENTIAL & PROPRIETARY INFORMATION23 VoIP – Train Analogy Real World –VoIP Packets dont always do what you want…

24 © 2009 JDSU. All rights reserved.JDSU CONFIDENTIAL & PROPRIETARY INFORMATION24 Metric: MOS Score, R-Factor Test the HFC Performance –VoIP Quality MOS R-Value –Processing Packet Loss Jitter Delay

25 © 2009 JDSU. All rights reserved.JDSU CONFIDENTIAL & PROPRIETARY INFORMATION25 Metrics: Delay, Packet Loss and Jitter Delay –Time it takes a packet to transverse the network –Too much delay affects the quality of a call Over-talk and Echo Usually an architecture (traffic/capacity) issue Generally not a HFC issue with equipment such as amplifiers CBAD X-Time Point A Point B CBAD Network Aim for 100ms or better

26 © 2009 JDSU. All rights reserved.JDSU CONFIDENTIAL & PROPRIETARY INFORMATION26 Metrics: Delay, Packet Loss and Jitter Packet Loss –Packet did not arrive (Point B) or out of sequence –Worse if it is bursty, many lost in a row – lossy –Can be architecture or physical layer Ingress (especially upstream) Routers over capacity (too full to hold any more) CBAD X-Time -Time Point A Point B CBAD Network Aim for 1% or better

27 © 2009 JDSU. All rights reserved.JDSU CONFIDENTIAL & PROPRIETARY INFORMATION27 Metrics: Delay, Packet Loss and Jitter Jitter –Packets not arriving with the same timing (different from X-Time) – time between packets is different –You never notice with Data, doesnt matter how the information arrives, just care that it shows up but VoIP is Real-Time Key Causes are IP packet routing, IP based equipment CBAD X-Time Point A Point B CBAD Slower than X Faster than X Slower than X CBAD Network Aim for 10ms or better

28 © 2009 JDSU. All rights reserved.JDSU CONFIDENTIAL & PROPRIETARY INFORMATION28 Use Metrics to Segment HFC and IP layer Segment HFC and IP impairments –Identify if issues are occurring in HFC Plant or in the IP network Check MOS of VoIP over DOCSIS channel Check VoIP packet statistics –Noise and Ingress on plant are major causes of Packet Loss

29 © 2009 JDSU. All rights reserved.JDSU CONFIDENTIAL & PROPRIETARY INFORMATION29 eMTA-CABLE MODEM 7 dB TAP Drop Cable High Pass Filter GROUND BLOCK 3-Way Splitter DIGITAL SET-TOP House 2-Way Amplifier Testing the Home for Ingress Contribution VoIP OLDER TV SET Return Equalizer ONLINE GAMING WIRELESS LAPTOP COMPUTER ETHERNET INGRESS SPECTRUM MEASUREMENTS

30 © 2009 JDSU. All rights reserved.JDSU CONFIDENTIAL & PROPRIETARY INFORMATION30 Adjust Goals Per Location

31 Future

32 © 2009 JDSU. All rights reserved.JDSU CONFIDENTIAL & PROPRIETARY INFORMATION32 DOCSIS 1.0 (High Speed Internet Access) –23 million products shipped worldwide as of YE2002 –228 CM Certified, 29 CMTS Qualified DOCSIS 1.1 (Voice, Gaming, Streaming) –Interoperable and backwards-compatible with DOCSIS 1.0 –Quality of Service and dynamic services, a MUST for PacketCable –In the field NOW - 64 CM Certified, 22 CMTS Qualified DOCSIS 2.0 (Capacity for Symmetric Services) –Interoperable and backwards compatible with DOCSIS 1.x –More upstream capacity than DOCSIS 1.0 (x6) & DOCSIS 1.1 (x3) –Improved robustness against interference (A-TDMA and S-CDMA) DOCSIS 3.0 (Channel Bonding) –Interoperable and backwards compatible with DOCSIS 1.x & 2.0 –Specification released for about 2 years –More deployments under way DOCSIS ® Versions at a Glance

33 © 2009 JDSU. All rights reserved.JDSU CONFIDENTIAL & PROPRIETARY INFORMATION33 DOCSIS ® 3.0 – Channel Bonding 256QAM = ~40Mbps (38.8 Mbps) Individual 256 QAM DOCSIS channel Versions 1.0/1.1/2.0 used only one channel for upstream and one channel for downstream communications 4 x 256QAM 4 x ~40Mbps = ~160 Mbps BONDED

34 © 2009 JDSU. All rights reserved.JDSU CONFIDENTIAL & PROPRIETARY INFORMATION34 Trends in the upstream Expanding digital environment –Upstream becoming increasingly crowded –More carriers More challenging than before –Wider carriers offer a wider target for interference –Higher modulation has more sensitivity to ingress

35 © 2009 JDSU. All rights reserved.JDSU CONFIDENTIAL & PROPRIETARY INFORMATION35 Use constellations to view impairments Microreflections etc. Microreflection pattern over time Cloud pattern over time

36 © 2009 JDSU. All rights reserved.JDSU CONFIDENTIAL & PROPRIETARY INFORMATION36 Back to the Basics Most problems are still physical layer issues Most of the test strategy remains the same –Divide and conquer Check forward and return RF levels –analog and digital Check for leakage Sweep the forward / reverse to detect issues Replace questionable connectors / passives Tighten F-connectors … but not too tight Robust plant will be ready for the next great thing

37 © 2009 JDSU. All rights reserved.JDSU CONFIDENTIAL & PROPRIETARY INFORMATION37 Future Services

38 © 2009 JDSU. All rights reserved.JDSU CONFIDENTIAL & PROPRIETARY INFORMATION38 Thank you! Carlene Gardner JDSU Cable Networks Division


Download ppt "Triple-Play Service Testing Carlene Gardner Strategic Marketing Manager JDSU Cable Networks Division For CCTA Training, San Juan PR, August 26, 2009."

Similar presentations


Ads by Google