dynamic coordination of signal processing functions using itu-t rec. g.799.2
DESCRIPTION
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. - PowerPoint PPT PresentationTRANSCRIPT
InternationalTelecommunicationUnion
Dynamic Coordination of Signal Processing Functions Using
ITU-T Rec. G.799.2
Dominic HoEricsson 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)
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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.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
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SPE and SPFGeneric Call Connection:
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SPE-1 SPE-2 SPE-3
SPE (Signal Processing Equipment)
NetworkMobile
AECG.160
ALCG.169
NRG.160
ECG.168
ALEG.169
SPF (Signal Processing Function):
• AEC
• ALC
• EC
• ALE
• NR
SPE-0
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Scope and Applicability of G.799.2
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.799.2
G.799.2 covers the coordination of SPFs in network equipment and in terminal devices
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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
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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
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Capability List Format7 6 5 4 3 2 1 0 Descriptions
V F N
Common Part SPID
Length
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): SPF 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
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SPF ID
AEC 0 0 0 1
ALC 0 0 1 0
EC 0 0 1 1
ALE 0 1 0 0
NR 0 1 0 1
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Capability List Exchange
Signal Processing
Equipment(SPE)
ForwardCapability
ListUpdate
ReverseCapability
ListUpdate
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
ForwardCapability
ListReceived
ReverseCapability
ListReceived
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Example of Information Exchange
SPE1 SPE2
…
A1
B1
A1
B1
C2
A1
B1
An-1
Bn
Cn
Dn-1
An-1
Bn
Cn
Dn-1
An-1
Bn
Cn
Dn-1
An-1
Bn
Cn
Dn-1
SPEnSPEn-1
A1
B1
C2
Dn-1
A1
B1
C2
A1
B1
C2
Dn-1
A1
B1
C2
Dn-1
Bn
Cn
An-1
Bn
Cn
Dn-1
Bn
Cn
Forward Capability List
Reverse Capability List
Forward and reverse capability lists for bear traffic from left to Right
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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
AEC High Preference Medium Preference Low Preference
NR High Preference Medium Preference Low Preference
ALE Low Preference Medium Preference High Preference
Acoustic echo
SPNE-1 SPNE-2 SPNE-3
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Coordination Examples
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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 encoderDec: Low bit rate decoderALE: Automatic Listener EnhancementALC: Automatic Level ControlAEC: Acoustic Echo Control
IPEnc ALE
Dec AEC ALE
ALE AEC Dec
ALE Enc
MG2
AEC Dec
MG3
MS2MS1
EncAEC
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MG1
Encoded speech from MS1
Encoded speech to MS1
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SPF Coordination : Before Handover
Enc: Low bit rate encoderDec: Low bit rate decoderALE: Automatic Listener EnhancementALC: Automatic Level ControlAEC: Acoustic Echo Control
Enc ALE
ALE Enc
MG2
AEC Dec
MG3
MS2EncAEC
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
Dec AEC ALE
IP
For Traffic flow from MS1 to MS2
ALE AEC Dec
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MS1
MG1
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SPF Coordination : After Handover
Enc: Low bit rate encoderDec: Low bit rate decoderALE: Automatic Listener EnhancementALC: Automatic Level ControlAEC: Acoustic Echo Control
Enc ALE
Dec AEC ALE
ALE AEC Dec
ALE Enc
MG2
AEC Dec
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
EncAEC
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MS1
MG1
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Generic 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.799.2
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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)
Tandem(results)SPNE-TMGW-TMGW-OMS-O
Voice enhancementprocessing functions
Q115
G799.2
Q.115.x ( Call set-up)
(Dynamic coordination) G.799.2
Coordination
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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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