Signalling for seamless interaction between networks and devices ITU-T SG16, Q18/16 Names

Motivation Modern telephony networks rely on a set of voice-quality enhancement (VQE) features 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 draft ITU-T G.MDCSPNE is to develop the generic framework for the dynamic coordination of VQEs present on bearer paths for the purpose of improving overall end-to-end voice quality

Scope and Applicability of G.MDCSPNE Media Path Signalling Path Mobile Phone IP packet network SPNE-T MGW-OMGW-T BSC-O MSC-O MSC-T Server Land User SC-T Server Circuit-Switched network Q.115.xG.MDCSPNE

Challenges in Mobility Communications Acoustic Echo Hybrid Echo - Automatic Level Control - Acoustic Echo Control - Automatic Level Control - Feedback Automatic Level Control - Network Echo Canceller - Acoustic Echo Control Dynamic VQE insertion/removal due to dynamic call configuration and modification Permutation of points of VQE feature deployment Variety of topologies : inter-MSC, intra-MSC Example of Use Cases: –Mobile-land calls –Mobile-mobile calls –Mobile calls with handover –Mobile calls with call transfer –Landline calls transferred to mobile

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

Capability List Format Descriptions V F N SPID Length Common Part Reserved ID Entry 1 Reserved Len Attribute Reserved ID Entry 2 Reserved Len Attribute Common part: V (3 bits): Version number F (1 bit): Forward / Reverse flag N (4 bits): Number of entries SPID (16 bits): SPNE/device Identifier Length (8 bits): Capability-list size in bytes (common + entries) Entry part: ID (4 bits): VQE entry identifier Len (4 bits): Entry size in bytes, including the entry ID byte and the entry Len byte and the attribute bytes Attribute: Entry attribute information with zero, one or multiple bytes (To be defined) Reserved: Reserved field with a value of 0x00

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

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 FBALC : 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) Signal Processing Functions Preferred Location for Signal Processing Functions AECHigh PreferenceMedium PreferenceLow Preference ALCHigh PreferenceMedium PreferenceLow Preference NRHigh PreferenceMedium PreferenceLow Preference Acoustic echo SPNE-1SPNE-2SPNE-3

Coordination Examples

VoIP Mobile-Mobile Call With Handover Call flow: –Mobile-mobile call between MS-1 and MS-2 via media gateways MG-1 and MG-2 –MS-2 experiences a handover –Mobile-mobile call between MS-1 and MS-2 via media gateways MG-1 and MG-3 Enc: Low bit rate encoder Dec: Low bit rate decoder FBALC: Feedback Automatic Level Control ALC: Automatic Level Control AEC: Acoustic Echo Control IP EncFBALC DecAECALC FBALCAECDec FBALCEnc MG2 AECDec Enc MG3 MS2 MS1 MG1 AEC

VQE Coordination : Before Handover Enc: Low bit rate encoder Dec: Low bit rate decoder FBALC: Feedback Automatic Level Control ALC: Automatic Level Control AEC: Acoustic Echo Control EncFBALC DecAECALC FBALCAECDec FBALCEnc MG2 AECDec Enc MG3 MS2 MS1 MG1 AEC 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 IP For Traffic flow from MS1 to MS2

VQE Coordination : After Handover Enc: Low bit rate encoder Dec: Low bit rate decoder FBALC: Feedback Automatic Level Control ALC: Automatic Level Control AEC: Acoustic Echo Control EncFBALC DecAECALC FBALCAECDec FBALCEnc MG2 AECDec Enc MG3 MS2 MS1 MG1 AEC MG-1 –realizes that it is the first and last one with ALC, and it is the first but not the last with AEC on MS-1 MS-2 traffic, MG-3 –realizes that there is an AEC upstream closer to the source on MS-1 MS-2 traffic Coordination Outcome –MG-1 continues AEC support on MS-1 MS-2 traffic. –MG-1 dynamically re-enables ALC support on MS-1 MS-2 traffic. –MG-3 disables its AEC. IP For Traffic flow from MS1 to MS2

Generic Network Configuration Mobile Phone IP packet network SPNE-T MGW-OMGW-T BSC-O MSC-O MSC-T Server Media Path Signalling Path Land User SC-T Server Circuit-Switched network Q.115.xG.MDCSPNE

Coordination Yes No Yes Enabled Yes Disabled Yes Disabled No Noise reduction (NR-T) for media from the land user Yes No Yes Enabled Yes Disabled No Echo Cancellation (EC) for S in from the land user Yes No Yes Disabled Yes Disabled Yes Disabled Yes Enabled Noise reduction (NR-O) for media from the mobile user Yes No Yes Disabled Yes Enabled Acoustic Echo Control (AEC) Tandeming (results) SPNE-TMGW-TMGW-OMS-O Voice enhancement processing functions Q G Q.115.x Call set-up) (Dynamic coordination) G.MDCSPNE

Dynamic Coordination of SPNE (G.MDCSPNE) – current status & future plans Dynamic Coordination of SPNE (G.MDCSPNE) – current status & future plans Q18/16 has almost reached consensus on coordination mechanism and proceeded to discuss detailed designs, Study on the protocols to exchange Capability Lists are necessary, SG16 is asking SG11 and other SDOs for the guidance on the available protocols, especially for wireless links, SG11 and other SDOs are invited to liaise with SG16 on these aspects, The separation of frame work part and implementation- dependent parts have been agreed, The target date for AAP consent on core part is expected to be at the SG16 meeting to be held in October 2009.