Signalling for seamlessSignalling for seamlessinteraction between networks interaction between networks

and devicesand devices

ITU-T SG16,ITU-T SG16, 　　 Q18/16Q18/16NamesNames

MotivationMotivationModern 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.MDCSPNEScope and Applicability of G.MDCSPNE

Media　Path

Signalling　Path

Mobile Phone

IP packet network

SPNE-TMGW-O MGW-T

BSC-O

MSC-O MSC-TServer

Land User

SC-TServer

Circuit-Switched network

Q.115.xG.MDCSPNE

Challenges in Mobility CommunicationsChallenges 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 MechanismDynamic 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 FormatCapability List Format7 6 5 4 3 2 1 0 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 ExchangeCapability List Exchange

Speech Processing

Functions/Devices

ForwardCapability

ListUpdate

ReverseCapability

ListUpdate

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

ForwardCapability

ListReceived

ReverseCapability

ListReceived

VQE Engagement RulesAEC : 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

AEC High Preference Medium Preference Low Preference

ALC High Preference Medium Preference Low Preference

NR High Preference Medium Preference Low Preference

Acoustic echo

SPNE-1 SPNE-2 SPNE-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 encoderDec: Low bit rate decoderFBALC: Feedback Automatic Level ControlALC: Automatic Level ControlAEC: Acoustic Echo Control

IPEnc FBALC

Dec AEC ALC

FBALC AEC Dec

FBALC Enc

MG2

AEC Dec

Enc

MG3

MS2

MS1 MG1 AEC

VQE Coordination : Before Handover

Enc: Low bit rate encoderDec: Low bit rate decoderFBALC: Feedback Automatic Level ControlALC: Automatic Level ControlAEC: Acoustic Echo Control

Enc FBALC

Dec AEC ALC

FBALC AEC Dec

FBALC Enc

MG2

AEC Dec

Enc

MG3

MS2

MS1 MG1 AEC

MG-1 – realizes that it is the first and last SPNE supporting AEC on MS-1MS-2 traffic– realizes that it is the first SPNE supporting ALC but there is a FBALC downstream on MS-

1MS-2 traffic MG-2

– realizes that there is an ALC upstream but it is the last one with FBALC on MS-1MS-2 traffic Coordination Outcome

– According to the preference rule, MG-2 continues FBALC support on MS-1MS-2 traffic, and MG-1 disables ALC on MS-1MS-2 traffic

IP

For Traffic flow from MS1 to MS2

VQE Coordination : After Handover

Enc: Low bit rate encoderDec: Low bit rate decoderFBALC: Feedback Automatic Level ControlALC: Automatic Level ControlAEC: Acoustic Echo Control

Enc FBALC

Dec AEC ALC

FBALC AEC Dec

FBALC Enc

MG2

AEC Dec

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-1MS-2 traffic, MG-3

– realizes that there is an AEC upstream closer to the source on MS-1MS-2 traffic Coordination Outcome

– MG-1 continues AEC support on MS-1MS-2 traffic.– MG-1 dynamically re-enables ALC support on MS-1MS-2 traffic.– MG-3 disables its AEC.

IP

For Traffic flow from MS1 to MS2

Generic Network ConfigurationGeneric Network Configuration

Mobile Phone

IP packet network

SPNE-TMGW-O MGW-T

BSC-O

MSC-O MSC-TServer

Media　Path

Signalling　Path

Land User

SC-TServer

Circuit-Switched network

Q.115.xG.MDCSPNE

Coordination 　

Yes

Yes

No

Yes

Enabled

Enabled

Yes

Disabled

Disabled

Yes

Yes

Disabled

No

No

No

Noise reduction (NR-T) for media from the land user

Yes

No

No

Yes

Enabled

Enabled

Yes

Disabled

Disabled

No

No

No

No

No

No

Echo Cancellation (EC) for Sin from the land

user

Yes

Yes

No

Yes

Disabled

Disabled

Yes

Yes

Disabled

Yes

Yes

Disabled

Yes

Yes

Enabled

Noise reduction (NR-O) for media from the mobile user

Yes

Yes

No

No

No

No

No

No

No

Yes

Yes

Disabled

Yes

Yes

Enabled

Acoustic Echo Control (AEC)

Tandeming(results)

SPNE-TMGW-TMGW-OMS-OVoice enhancement

processing functions

Q

G

Q.115.x （ Call set-up)

(Dynamic coordination) G.MDCSPNE

Dynamic Coordination of SPNE (G.MDCSPNE) Dynamic Coordination of SPNE (G.MDCSPNE) – current status & future plans – 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.