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Dynamic Coordination of Signal Processing Functions Using ITU-T Rec. G.799.2

ITU-T Workshop on “Interactions of Vocieband Signal processing Functions and their End-to-End Coordination” (Germantown, Maryland, USA. 21 April 2010). Dynamic Coordination of Signal Processing Functions Using ITU-T Rec. G.799.2. Dominic Ho Ericsson Canada Inc. Mont-Royal, Quebec, Canada.

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Dynamic Coordination of Signal Processing Functions Using ITU-T Rec. G.799.2

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  1. ITU-T Workshop on “Interactions of Vocieband Signal processing Functions and their End-to-End Coordination” (Germantown, Maryland, USA. 21 April 2010) Dynamic Coordination of Signal Processing Functions Using ITU-T Rec. G.799.2 Dominic Ho Ericsson Canada Inc. Mont-Royal, Quebec, Canada

  2. Modern telephony networks uses voice-quality enhancement (VQE) features, denoted as Signal Processing Functions (SPFs), for optimum quality of experience • For maximum effectiveness of VQE features it is necessary: • -To deploy all applicable VQE features • - To avoid multiple (tandem) application of the same feature • - To exercise the feature at the optimal location along the call path • The intent of ITU-T Rec. G.799.2 is to develop the mechanism framework for the dynamic coordination of VQEs present on bearer paths for the purpose of improving overall end-to-end voice quality Motivation 2

  3. Generic Call Connection: SPE-1 SPE-2 SPE-3 SPE-0 SPE and SPF SPE (Signal Processing Equipment) • SPF (Signal Processing Function): • AEC • ALC • EC • ALE • NR AEC NR ALC G .160 G .160 G.169 Network Mobile EC ALE G.168 G.169 3

  4. Scope and Applicability of G.799.2 SC-T Server MSC-T Server MSC-O MGW-O MGW-T SPNE-T BSC-O Circuit-Switchednetwork IP packet network Land User Mobile Phone G.799.2 Q.115.x Media Path Signalling Path G.799.2 covers the coordination of SPFs in network equipment and in terminal devices

  5. Challenges in Mobility Communications • Dynamic SPF insertion/removal due to dynamic call configuration and modification • Permutation of points of SPF deployment • Variety of topologies : inter-MSC, intra-MSC • Examples of Call Connection Cases: • Mobile-land calls • Mobile-mobile calls • Mobile calls with handover • Mobile calls with call transfer • Landline calls transferred to mobile • - ALC • EC • - ALE • AEC • ALC • ALE • ALC • - EC • AEC Acoustic Echo Hybrid Echo

  6. Dynamic Coordination Mechanism • Dynamic coordination of SPF is achieved through: • An encapsulation format (capability list) to facilitate identification of SPF capabilities from different equipment/devices in a dynamic manner • Rules for exchange of capability lists among nodes in a call-path, for SPF coordination in static and dynamic call configurations • SPF engagement rules executed by individual equipment/devices based on common view of capabilities available along a given bearer path

  7. Capability List Format

  8. Each entry(cell) corresponds to a specific Signal Processing Function • Signal Processing Function includes, but is not limited to: • Network Echo Cancellation (EC), • Acoustic Echo Control (AEC), • Automatic Level Control (ALC), • Noise Reduction (NR), • Automatic Listener Enhancement • (ALE) • Capability List received is updated with new information and sent to next SPE, if necessary • Each SPE enables or disables its function based on Capability view, in accordance with pre-determined coordination rules Forward Capability List Received Forward Capability List Update Capability List Exchange Signal Processing Equipment(SPE) Signal Flow Reverse Capability List Update Reverse Capability List Received 8

  9. A1 A1 An-1 A1 An-1 A1 An-1 An-1 A1 A1 An-1 B1 Bn Bn B1 B1 Bn Bn Bn Bn B1 B1 Bn B1 Cn Cn Cn C2 Cn Cn Cn Cn C2 C2 C2 Dn-1 Dn-1 Dn-1 Dn-1 Dn-1 Dn-1 Dn-1 Dn-1 A1 B1 C2 … SPE1 SPE2 SPEn-1 SPEn Forward and reverse capability lists for bear traffic from left to Right Forward Capability List Example of Information Exchange Reverse Capability List 9

  10. VQE Engagement Rules • AEC : as close as possible to the source of acoustic echo • ALC : as close as possible to the signal source • EC : as close as possible to the local loop • ALE : as close as possible to the destination • NR : as close as possible to the signal source Engagement example in mobile-land call (for bearer traffic from left to right) SPNE-1 SPNE-2 SPNE-3 Acoustic echo 10

  11. Coordination Examples 11

  12. VoIP Mobile-Mobile Call With Handover Call flow: - Mobile-mobile call between MS1 and MS2 via media gateways MG1 and MG2 - MS2 experiences a handover - Mobile-mobile call between MS1 and MS2 via media gateways MG1 and MG3 MG2 Encoded speech from MS1 ALE AEC Dec ALE Enc IP Dec AEC ALE Enc ALE MS1 MS2 AEC Dec MG1 Enc AEC Encoded speech to MS1 MG3 Enc: Low bit rate encoder Dec: Low bit rate decoder ALE: Automatic Listener Enhancement ALC: Automatic Level Control AEC: Acoustic Echo Control 12

  13. SPF Coordination : Before Handover MG-1 - realizes that it is the first and last SPNE supporting AEC on MS-1MS-2 traffic - realizes that it is the first SPNE supporting ALC but there is a FBALC downstream on MS-1MS-2 traffic MG-2 - realizes that there is an ALC upstream but it is the last one with FBALC on MS-1MS-2 traffic Coordination Outcome - According to the preference rule, MG-2 continues FBALC support on MS-1MS-2 traffic, and MG-1 disables ALC on MS-1MS-2 traffic For Traffic flow from MS1 to MS2 MG2 ALE AEC Dec ALE Enc IP ALE Dec AEC Enc ALE MS1 MS2 AEC Dec MG1 Enc AEC MG3 Enc: Low bit rate encoder Dec: Low bit rate decoder ALE: Automatic Listener Enhancement ALC: Automatic Level Control AEC: Acoustic Echo Control 13

  14. SPF Coordination : After Handover For Traffic flow from MS1 to MS2 • MG1 • - realizes that it is the first and last one with ALC, and it is the first but not the last with AEC on MS1  MS2 traffic, • MG3 • - realizes that there is an AEC upstream closer to the source on MS1  MS2 traffic • Coordination Outcome • - MG1 continues AEC support on MS1  MS2 traffic. • - MG1 dynamically re-enables ALC support on MS1  MS2 traffic. • - MG3 disables its AEC. MG2 ALE AEC Dec ALE Enc IP Enc ALE Dec AEC ALE MS1 MS2 AEC Dec MG1 Enc AEC MG3 Enc: Low bit rate encoder Dec: Low bit rate decoder ALE: Automatic Listener Enhancement ALC: Automatic Level Control AEC: Acoustic Echo Control 14

  15. Generic Network Configuration SC-T Server MSC-T Server MSC-O MGW-O MGW-T SPNE-T BSC-O Circuit-Switchednetwork IP packet network Land User Mobile Phone G.799.2 Q.115.x Media Path Signalling Path 15

  16. Voice enhancement processing functions MS-O MGW-O MGW-T SPNE-T Tandem (results) Acoustic Echo Control (AEC) Yes Yes Enabled Yes Yes Disabled No No No No No No Yes Yes No Q115 G799.2 Noise reduction (NR-O) for media from the mobile user Yes Yes Enabled Yes Yes Disabled Yes Yes Disabled Yes Disabled Disabled Yes Yes No Echo Cancellation (EC) for Sin from the land user No No No No No No Yes Disabled Disabled Yes Enabled Enabled Yes No No Noise reduction (NR-T) for media from the land user No No No Yes Yes Disabled Yes Disabled Disabled Yes Enabled Enabled Yes Yes No (Dynamic coordination) G.799.2 Q.115.x（Call set-up) Coordination

  17. Current Status & Future Plans • G.799.2 has been approved as an ITU-T Recommendation end of last year(12/09) • G.799.2 contains the framework and mechanism for dynamic coordination of SPF • Development of protocols to implement G.799.2 will be in separate ITU-T Recommendations • SG16 is requesting SG11 and other SDOs for the guidance on the available protocols, especially for wireless links

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