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Consult 21 Interconnect Working Group

Consult 21 Interconnect Working Group. 15 th December 2005. Allan Good Complex Routed Calls (Impact of 21CN on Transmission Delay).

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Consult 21 Interconnect Working Group

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  1. Consult 21 Interconnect Working Group 15th December 2005 Allan Good Complex Routed Calls (Impact of 21CN on Transmission Delay) The information in this presentation relates to plans currently under development and subject to consultation, and may be subject to change. Detailed implementation depends upon a number of factors including the capabilities of suppliers and the final 21CN network design.

  2. This session: • What is the cause of delay and echo • This is a good story • Examples of Complex Routed Calls • A look at extracts from: • The UK National Transmission Plan • Some examples • Summary

  3. What is the cause of delay and echo • As you add technical elements to a network, the speech • delay increases • At a certain limit Echo Cancellation Devices are required • During migration to 21CN speech delays will increase • As networks migrate to NGN Interconnect, speech delay will reduce

  4. This is a good story • BT will provide echo cancellation devices as it converts its network to NGN • CPs networks which already fall outside the industry limits on echo should have provided echo cancellation devices • CPs need to provide echo cancellation devices to ensure QOS when migrating to a NGN • Consider a possible worse case Complex Routed Call

  5. Callingparty Example of a Complex Routed Call Fixed line with CPS to Mobile with Number Portability CPS TRANSIT CP FIXED CPE CONCENTRATOR DLE NGS/DMSU Ported Mobile Number MOBILE CP CPS CP TRANSIT Called Party TERMINATING MOBILE NETWORK TRANSIT MOBILE CPE

  6. 21CN Fixed line call to NTS Ported Number ORIGINATING CPE GW MGW MSAN MN NGS/HYBRID Non – Geographic Ported Number NTS CP RANGE HOLDER CPS CP TRANSIT CPS TRANSIT CP Ported Geographic Number Translates To Deliver To Number RECIPIENT NTS CP GEOGRAPHIC CP TRANSIT TRANSIT TERMINATING CPE GEOGRAPHICCP TRANSIT

  7. From the UK National Transmission Plan ND1701 • Without - Echo Cancellation • NTP-NTP one-way delay should be less than 15ms for at least 95% of calls • For the small proportion of calls that exceed the 15ms limit, an absolute limit of 25ms is recommended • With - Echo Cancellation • For UK fixed line to fixed line, or fixed line to digital mobile with echo cancellation:95% of national connections should meet a 125ms one-way delay limit no connections should exceed 150ms • For UK digital mobile to digital mobile with echo cancellation:95% of national connections should meet a 215ms one-way delay limit no connections should exceed 230ms

  8. Analysis • BT has done some calculations on Complex Calls based on the following assumptions : • Single MSAN = 12.5ms delay • Single MN = 1ms delay • Single MGW = 12.5ms delay • Jitter is within specification and absorbed by the jitter buffer, i.e. Jitter does not produce significant packet loss allowing use of ISDN Clear mode • All components are within specification and therefore analogue performance e.g. overall loudness rating & sig to noise etc is not an issue.

  9. Points to note • 1) All 21CN calls will have a longer delay than their TDM counterparts due to the 26 ms MSAN to MGW delay • Even the simplest 21CN call will require echo cancellation due to MSAN to MGW delay of 26 ms • 3) All simple PSTN call types between BT and a Fixed CP are less than 100 ms NTP-to-NTP and therefore well within the limits specified in ND1701 • Longer delays may occur where a call encounters a third party CP’s network, which can add up to 35 ms delay • Taking the worst case scenario and adding 21CN does not increase the delay significantly

  10. Some examples

  11. Summary CPS + CP Transit + BT NP Transit 201 with fixed termination UK PSTN Call (from ITU-T Recommendation G.114) CPS + CP Transit + BT NP Transit 249 with mobile termination NGN to NGN UK complex call with some 21CN elements UK complex call with some 21CN elements and mobile at one end Graph extracted from G.114

  12. Conclusion • We have looked at • the cause of delay and echo • the need for echo cancellation devises • examples of Complex Routed Calls • extracts from the UK National Transmission Plan • some examples • impact summary on G114 graph

  13. End

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