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

International Telecommunication Union Motivation  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 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 2

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

International Telecommunication Union Scope and Applicability of G 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 G covers the coordination of SPFs in network equipment and in terminal devices 4

International Telecommunication Union Challenges in Mobility Communications Acoustic Echo Hybrid Echo - AEC - ALC - ALE - ALC - EC - ALE - ALC - EC - AEC 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 5

International Telecommunication Union 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 6

International Telecommunication Union Capability List Format 7 SPFID AEC ALC EC ALE NR 0 1

International Telecommunication Union Capability List Exchange Signal Processing Equipment(SPE) Forward Capability List Update Reverse Capability List Update Signal Flow  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 Reverse Capability List Received 8

International Telecommunication Union Example of Information Exchange SPE 1 SPE 2 … A1A1 B1B1 A1A1 B1B1 C2C2 A1A1 B1B1 A n-1 BnBn CnCn D n-1 A n-1 BnBn CnCn D n-1 A n-1 BnBn CnCn D n-1 A n-1 BnBn CnCn D n-1 SPE n SPE n-1 A1A1 B1B1 C2C2 D n-1 A1A1 B1B1 C2C2 A1A1 B1B1 C2C2 A1A1 B1B1 C2C2 BnBn CnCn A n-1 BnBn CnCn D n-1 BnBn CnCn Forward Capability List Reverse Capability List Forward and reverse capability lists for bear traffic from left to Right 9

International Telecommunication Union 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) Signal Processing Functions Preferred Location for Signal Processing Functions AECHigh PreferenceMedium PreferenceLow Preference NRHigh PreferenceMedium PreferenceLow Preference ALELow PreferenceMedium PreferenceHigh Preference Acoustic echo SPNE-1SPNE-2SPNE-3 10

International Telecommunication Union Coordination Examples 11

International Telecommunication Union 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 Enc: Low bit rate encoder Dec: Low bit rate decoder ALE: Automatic Listener Enhancement ALC: Automatic Level Control AEC: Acoustic Echo Control IP EncALE DecAECALE AECDecALEEnc MG2 AECDec MG3 MS2 MS1 Enc AEC 12 MG1 Encoded speech from MS1 Encoded speech to MS1

International Telecommunication Union SPF Coordination : Before Handover Enc: Low bit rate encoder Dec: Low bit rate decoder ALE: Automatic Listener Enhancement ALC: Automatic Level Control AEC: Acoustic Echo Control EncALE Enc MG2 AECDec MG3 MS2 Enc 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 DecAEC ALE IP For Traffic flow from MS1 to MS2 ALEAECDec 13 MS1 MG1

International Telecommunication Union SPF Coordination : After Handover Enc: Low bit rate encoder Dec: Low bit rate decoder ALE: Automatic Listener Enhancement ALC: Automatic Level Control AEC: Acoustic Echo Control EncALEDecAECALE AECDecALEEnc MG2 AECDec MG3 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. IP For Traffic flow from MS1 to MS2 Enc AEC 14 MS1 MG1

International Telecommunication Union 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

International Telecommunication Union 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) Tandem (results) SPNE-TMGW-TMGW-OMS-O Voice enhancement processing functions Q115 G799.2 Q.115.x （ Call set- up) (Dynamic coordination) G Coordination 16

International Telecommunication Union Current Status & Future Plans  G has been approved as an ITU-T Recommendation end of last year(12/09)  G contains the framework and mechanism for dynamic coordination of SPF  Development of protocols to implement G 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 17