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Jack Douglass, Spirent Chair TIA TR30.3

Standard IP Network Model for Comparing Voice Quality of IP Telephony Devices Dolby VoIP? How close are we to better than PSTN Sound?. Jack Douglass, Spirent Chair TIA TR30.3. How close are we to better than PSTN Sound?.

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Jack Douglass, Spirent Chair TIA TR30.3

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  1. Standard IP Network Model for Comparing Voice Quality of IP Telephony Devices Dolby VoIP? How close are we to better than PSTN Sound? Jack Douglass, Spirent Chair TIA TR30.3

  2. How close are we to better than PSTN Sound? • An objective method of measuring and comparing the Audio Quality and Performance of IP Telephony Equipment in the presence of Network Impairments is needed • A Standard Network Model for Evaluating Multimedia Transmission Performance Over Internet Protocol • Audio Quality must be measured over time-varying network impairments that are statistically accurate • TIA TR30.3 is working with the ITU-T on a Statistically Based IP Network Model • Will become TIA-921when released • Submit to ITU-T for consideration as a Recommendation

  3. Converged IP Telephony Network is Very Complex and has Many Impairments Signaling Path

  4. Network Topologies that need be considered when testing Audio Quality over a Converged Network

  5. Converged Network Reference Model Diagram A A D D Gateway Gateway TE TE L L Telco Switch Telco Switch IP Network R,G,S* L L Gateway R,G,S* R,G,S* Gateway

  6. Parameters & Impairments that Need to be Considered when Simulating an IP Network • Network Architecture • Types of Access Links • QoS controlled Edge Routing • Route Flapping • Link Failure • Load Sharing • Time Drift • MTU Size • Packet Loss • Background Traffic (Congestion, Bandwidth, Utilization, Network Load) • One Way Delay

  7. Sources of IP Network Impairments

  8. IP Network Model

  9. Packet Delay Time Example of Test Profile with Time Variable Network Impairments

  10. Each Impairment Condition is assigned a Likely-hood of Occurrence (LOO) based on real IP Network Statistics, Network Architecture, Classes of Service The goal is to have approximately 100 test combinations so that an automated run of the test suite completes in less than a day. IC1 LOO X% IC2 LOO X% IC100 LOO X% Time Time Varying Statistically Based IP Network Impairment Conditions (ICs)

  11. Statistically based models can be created for different QoS Classes Test Profiles Based on QoS Classes

  12. Parameter X Vs Network Model Coverage Percentage Device A Device B Device C PESQ, PSQM, MOS, R-Factor, Throughput, Connect Rate, etc. 0 0 10 20 30 40 50 60 70 80 90 100 Percentage of Network Coverage Example of Network Model Coverage (NMC) Curve

  13. Examples of Communication Equipment that can be tested over the Converged Network Model • Plain Old Telephone Service (POTS) and IP telephones • PSTN Video H320 and H324 • IP Network Devices such as User Agents, Call Agents, Media Servers, Media Gateway Controllers, Gatekeepers, Application Servers, Edge Routers, Gateways, IP Phones, IAF (Internet Aware Fax) • Voice-over-IP (VoIP) gateways • T.38 facsimile devices and gateways • V.150.1 and voiceband data (VBD) modem-over-IP gateways • TIA-1001 (and V.toip) textphone-over-IP gateways

  14. TR30.3 Test Standards • TIA/EIA 496A-1989: Interface Between Data Circuit Terminating Equipment (DCE) and the Public Switched Telephone Network • Included Network Model for Evaluating Modem Performance • TIA/EIA TSB 37A-1994:Telephone Network Transmission Model for Evaluating Analog Modem Performance, whichbecameITU-T Recommendation V.56bis-1995 • EIA/TIA TSB 38-1994:Test Procedures for Evaluation of 2-Wire 4 Kilohertz Voice Band Duplex Modems, whichbecame ITU-T Recommendation V.56ter-1996 • ANSI/TIA/EIA 3700-1999:Telephone Network Transmission Model for Evaluating Analog Modem Performance • ANSI/TIA/EIA 793 -2000:North American Telephone Network Transmission Model for Evaluating Analog Client and Digitally Connected Server Modems • ANSI/TIA 876 – 2002: North American Network Access Transmission Model for Evaluating xDSL Modem Performance

  15. Value of Converged Network Model • Predicts product performance under statistically based network conditions • Finds design weaknesses • Find compatibility issues between network equipment • Facilitates isolating and resolving field problems • Assists in evaluating different technologies • Competition for better performance over the Network Model drives the industry to create better quality products

  16. Target Audience for Converged Network Model • Operating Companies • Service Providers • Manufacturers • Design Engineers • Test houses • Magazines and product reviewers

  17. How will TIA-921 help the Industry Achieve Better than PSTN sound? • PSTN quality sound on the IP Network has not yet been achieved • The Network Model will provide a standard test bed • objectively compare the Audio Quality of various IP Telephony devices • Competition to perform better on the Network Model will help drive the Quality of IP Telephony sound to be better that PSTN sound

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