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30406013 Dolby VoIP Presentation

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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?
• 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
Converged IP Telephony Network is Very
Complex and has Many Impairments




               Signaling Path
Network Topologies that need be considered when
testing Audio Quality over a Converged Network
Converged Network Reference Model Diagram



     A                  D                                                          D                      A
         Telco Switch                          L                L                          Telco Switch
TE                          Gateway                IP Network            Gateway                              TE




                                                    R,G,S*



                        L                                                              L
           Gateway                    R,G,S*                        R,G,S*                   Gateway
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
Sources of IP Network Impairments
 IP Network Model


                                     Local Access                                        Local Access
 Source                                    A                                                   B                                      Destination
Device A
                   LAN A                                    Core IP Network                                    LAN B                   Device B
                                         64 kbit/s                                        64 kbit/s
                                        *128 kbit/s                                      *128 kbit/s
                                         256 kbit/s                                       256 kbit/s
           1000BaseX                    *384 kbit/s                                      *384 kbit/s         1000BaseX
           * 100BaseT Switch             512 kbit/s           Route flapping              512 kbit/s         * 100BaseT Switch
           100BaseT Hub                 *768 kbit/s           One-way delay              *768 kbit/s         100BaseT Hub
           10BaseT                 *T1 (1.536 kbit/s)             Jitter             *T1 (1.536 kbit/s)      10BaseT
           * WLAN (~4 Mbit/s) E1 (1.920 kbit/s)                Packet loss           E1 (1.920 kbit/s)       * WLAN (~4 Mbit/s)
           ----------------------     E3 (34 Mbit/s)                                   E3 (34 Mbit/s)        ----------------------
           Occupancy level           *T3 (44 Mbit/s)                                  *T3 (44 Mbit/s)        Occupancy level
           Packet loss            ADSL (~256 kbit/s)                                 ADSL (~2 Mbit/s)        Packet loss
                                  *Cable (~256 kbit/s)                              *Cable (~3 Mbit/s)
                                   Fiber (1-10 Gbit/s)                              Fiber (1-10 Gbit/s)
                                     --------------------                             --------------------
                                    Occupancy level                                  Occupancy level
                                    QoS edge router                                  QoS edge router

                                                      * Case used in impairment tables
       Example of Test Profile with Time
       Variable Network Impairments
Packet Delay




                      Time
 Time Varying Statistically Based IP
 Network Impairment Conditions (ICs)
IC1
LOO X%


IC2
LOO X%




IC100
LOO X%



                                      Time

      • 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.
Test Profiles Based on QoS Classes
Test Profiles   QoS Class   Applications (Examples)                    Node Mechanisms                    Network Techniques
                 (Y.1541)

     A             0        Real-Time, loss sensitive, Jitter                                             Constrained Routing and Distance
                                                                       Strict QoS. Guaranteed no over
(VoIP, MoIP,                sensitive, high interaction (VoIP, VTC)
                                                                       subscription on links.
 FoIP, ToIP)
     B             1        Real-Time, Jitter sensitive, interactive                                      Less constrained Routing and
                                                                       Separate Queue with preferential
(VoIP, MoIP,                (VoIP, VTC).                                                                  Distances
                                                                       servicing, Traffic grooming
 FoIP, ToIP)
    C              2        Transaction Data, Highly Interactive                                          Constrained Routing and Distance
(FoIP only)                 (Signaling)
                                                                       Separate Queue, Drop priority
                   3        Transaction Data, Interactive                                                 Less constrained Routing and
                                                                                                          Distances
                   4        Low Loss Only (Short Transactions,         Long Queue, Drop priority          Any route/path
                            Bulk Data, Video Streaming)
                   5        Traditional Applications of Default IP     Separate Queue (lowest priority)   Any route/path
                            Networks




    • Statistically based models can be created for different
           QoS Classes
Example of Network Model Coverage
(NMC) Curve
                                                                 Parameter X Vs Network Model Coverage Percentage
 PESQ, PSQM, MOS, R-Factor, Throughput, Connect Rate, etc.




                                                                                                                     Device A
                                                                                                                     Device B
                                                                                                                     Device C




                                                             0
                                                                 0     10     20     30    40     50     60     70   80    90   100

                                                                                    Percentage of Network Coverage
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
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, which became ITU-T
  Recommendation V.56bis-1995
• EIA/TIA TSB 38-1994: Test Procedures for Evaluation of 2-Wire
  4 Kilohertz Voice Band Duplex Modems, which became 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
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
Target Audience for Converged Network Model


•   Operating Companies
•   Service Providers
•   Manufacturers
•   Design Engineers
•   Test houses
•   Magazines and product reviewers
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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posted:6/2/2011
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