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Communications Alliance: Leading the Australian Communications Industry

Communications Alliance is a unified voice for the Australian communications industry, leading it into the next generation of networks, technologies, and services. This overview provides information on their activities and topics, with a focus on IP network quality of service and VoIP quality of service.

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Communications Alliance: Leading the Australian Communications Industry

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  1. Communications Alliance Overview and update AusNOG1, Sydney, Australia, 15 November 2007  James Duck Communications Alliance

  2. Communications Alliance  Created from a merger of ACIF and SPAN: “Communications Alliance was formed in 2006 to provide a unified voice for the Australian communications industry and to lead it into the next generation of converging networks, technologies and services.” A company resourced by its members Not a government body, nor a lobby group http://commsalliance.com.au

  3. Sample of CA Activities  Develop industry positions on policy Seminars, Forums, Roundtables Compliance Project basedWorking Groups/Committees Advisory Groups

  4. Sample of CA Topics  End user / Consumer premium services, accessibility, priority assistance, universal service, life threatening calls, etc. Customer Equipment Standards for phones, modems, filters, PBXs, etc. Networks, Operations ADSL(2+), VDSL, ordering, provisioning, numbering, emergency calls, law enforcement, infrastructure deployment, portability, etc.

  5. General trends  Next Generation / Emerging Services Transition from legacy to IP-based networks and services Services and applications may be decoupled from or integrated with networks Types of services High interactivity – voice/video calls/conferencing Lower interactivity – streaming video, file transfers So … what to focus on?

  6. What to focus on?  High impact Voice and video Networks and Services High sensitivity Sensitive to delay Sensitive to variability Two related topics emerged…

  7. IP Network Quality of Service  Define a default set of traffic classes Include delay, jitter and loss performance Packet marking and handling Align with international activity Produce related test documents Between User-Network Interfaces More information on Friday morning

  8. VoIP Quality of Service  Provide a measure of VoIP quality in a usable format e.g. ITU-T/ETSI E-model Consider Network IP QoS service classes Align with international activity Consider interworking with existing voice networks e.g. PSTN/ISDN. Assess requirements related to transcoding. Produce related test documents. Mouth to ear

  9. What is “Quality of Service”?  ITU-T “SANCHO” database ...http://www.itu.int/sancho/ Returns 20 answers Includes “dynamic” QoS and “extended” QoS What about “Quality of Experience” (QoE)? ITU held a two and half day“Workshop on "End-to-End QoE/QoS"”http://www.itu.int/ITU-T/worksem/qos/200606/programme.html MIT Communications Futures Programhttp://cfp.mit.edu/resources/index.html White paper on Inter-provider QoS SANCHO = “ITU-T Sector Abbreviations and defiNitions for a teleCommunications tHesaurus Oriented database”

  10. VoIP QoS  Based on: E model (ITU-T Rec. G.107) and R value (ITU-T Rec. G.108) Other options: Mean Opinion Score (MOS) (ITU-T Rec. P.800) arguably subjective, expensive, time consuming, inconvenient. Perceptual Evaluation of Speech Quality (PESQ) (ITU-T Rec. P.862) does not address conversational speech factors such as delay, signal level, echo, impairment.

  11. Factors affecting VoIP QoS  Major Factors affecting VoIP QoS: Delay Distortion e.g. codec choice Echo Loss / level plan Other factors include: Noise level e.g. room noise Advantage e.g. mobility, remote access Sidetone

  12. R Value from ITU-T G.108  R = Ro – Is – Id – Ie-eff + A, where: Ro = Signal to noise Is = combination of all impairments Id = impairments caused by delay Ie-eff = impairments caused by low bit rate codecs A = Advantage

  13. Transmission Rating (R) limits for voice services (1)

  14. Transmission Rating (R) limits for voice services (2)

  15. Impact of delay on QoS

  16. Impact of distortion / compression on R

  17. Impact of echo on R

  18. Impact of packet loss on R

  19. Codec choice and codec negotiation  Each codec has advantages and disadvantages: encoding via a frame codec (e.g. G.729) can introduce delay waveform codecs (e.g. G.711) require more bandwidth Include G.711 (A-law) as an available codec to ensure interoperability. Use packet loss concealment in conjunction with waveform codecs (e.g. G.711). Use RFC 3264 for codec negotiation between end points

  20. Codec choice - example  Waveform/Frame codecs require more/less bandwidth – example for 20ms sample: G.711 at 64kbps, IPv4: 200 bytes including 40 byte header 92 kbps over Ethernet G.729a at 8kbps, IPv4: 60 bytes including 40 byte header 37 kbps over Ethernet 8:1 ratio excluding header 2.5:1 ratio including header

  21. Bandwidth per voice calls with standard IP header(5% additional bandwidth allowed for RTCP packets) 

  22. Transcoding  Transcoding/Tandeming - successive encoding by different/same codecs Reduce and preferably eliminate it Support the G.711 (A-law) codec to avoid: transcoding (distortion) or Inability of endpoints to negotiate a mutually agreeable codec (i.e. call failure). Preferably no enforced transcoding on call gateway(s) at a point of interconnection should avoid transcoding between CELP codecs (e.g. G.729) or between CELP and ADPCM (G.726/G.722) codecs.

  23. Transport scenarios  Single Carrier IP Access and Core networks TDM access and core, IP access network Two Carriers TDM access and core, IP core and access. TDM Access & IP Core, IP Access Three Carriers IP Access, TDM Core, IP Access

  24. Other variables  Transport combinations Pure IP TDM to IP, IP to TDM, IP-TDM-IP IP-TDM-Mobile Access speeds Test types Design, Operational, Fault Equipment Analogue phone + ATA/IAD IP handset, DECT phone behind ATA, WiFi LAN segment

  25. VoIP QoS Status  Quality of Service parameters for Voice over Internet Protocol (VoIP) services Industry Guideline (CA G634:2007)published end October 2007http://commsalliance.com.au/documents/guidelines VoIP QoS Testing Arrangements Guideline (CA G635:2007) at ballot Complements IP Network QoS activity Next steps

  26. Other Activities – VoIP Working Group  technical, regulatory and consumer protection components of a voice service Fact sheets & guides for providers, end users Liaison with government e.g. ACMA and DCITA Interconnection subgroup Fault handling/restoration and customer support

  27. Possible Technical Activities  Interconnecting SIP services e.g. number formats (E.164, NSN, 0+NSN, ENUM) minimum codec set. Consistent approach to services e.g. how to handle DTMF tones on an IVR An interconnection model for IP based networks Define/adopt common technical interfaces, processes for interception IP Location Information Participation invited/welcome

  28. Contacts  W: http://commsalliance.com.au E: info@commsalliance.com.au T: +61 2 9959 9111 F: +61 2 9954 6136 Level 9, 32 Walker St, North Sydney P.O. Box 444, Milsons Point, NSW 1565

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