CCITT Rec. G.763 … DIGITAL CIRCUIT MULTIPLICATION EQUIPMENT USING 32 kbit/s ADPCM
AND DIGITAL SPEECH INTERPOLATION
FOREWORD
1 General
1.1 Scope
1.2 Purpose
1.3 Application
2 Definitions relating to digital circuit multiplication equipment (DCME)
2.1 digital circuit multiplication equipment (DCME)
2.2 digital circuit multiplication system (DCMS)
2.3 low rate encoding (LRE)
2.4 variable bit rate (VBR)
2.5 digital speech interpolation (DSI)
2.6 DCME frame
2.7 transmission channel
2.8 bearer channel (BC)
2.9 trunk channel (TC)
2.10 intermediate trunk (IT)
2.11 assignment message
2.12 assignment map
2.13 control channel (CC)
2.14 ensemble activity
2.15 speech activity factor
2.16 voice-band data ratio
2.17 64 kbit/s unrestricted digital data ratio
2.18 DCME overload (mode)
2.19 overload channels
2.20 average bits per sample
2.21 transmission overload
2.22 freeze-out
2.23 freeze-out fraction (FOF)
2.24 interpolation gain (IG)
2.25 transcoding gain (TG)
2.26 DCME gain (DCMG)
2.27 clique
2.28 multi-clique mode
2.29 multi-destination mode
2.30 silence elimination
3 DCME functions
3.1 General
3.2 Purpose
4 Operational modes
4.1 General
4.1.1 Point-to-point mode
4.1.2 Multi-clique mode
4.1.3 Multi-destination mode
4.1.4 Interoperation
4.2 Modes of assignment of channels to the bearer structure
4.2.1 Pre-assignment
4.2.2 Dynamic assignment
5 Interface requirements
5.1 Transmission interface: trunk side
5.1.1 Trunk side interface at 2048 kbit/s
5.1.2 Trunk side interface at 1544 kbit/s
5.2 Transmission interface: bearer side
5.2.1 Bearer side interface at 2048 kbit/s
5.2.2 Bearer side interface at 1544 kbit/s
5.3 Signalling interfaces to switching equipment (ISC)
5.3.1 DCME-ISC signalling interface functions
5.3.2 External and internal messages/indications
5.3.3 Circuit numbering translation
5.3.4 Transmission resource circuit mapping
5.4 Man-machine interface
5.5 Operations function interface
5.5.1 Trunk side operation at 2048 kbit/s or 1544 kbit/s
5.5.2 Bearer side
5.6 Local alarms interface
5.7 External clock interface
5.7.1 DCME working with 2048 kbit/s transmission interfaces
5.7.2 DCME working with 1544 kbit/s transmission interfaces
5.8 DCME frame structure
5.8.1 2048 kbit/s structure
5.8.2 1544 kbit/s structure
5.9 Bearer BC numbering and use of the bearer frame
5.9.1 8 bit (64 kbit/s) BCs
5.9.2 5-bit (40 kbit/s) BCs
5.9.3 Normal range 4-bit BCs
5.9.4 Normal range 4/3-bit (32/24 kbit/s) BCs
5.9.5 Overload range 4/3-bit (32/24 kbit/s) BCs
5.9.6 Normal and overload range 3/2 bit (24/16 kbit/s) BCs resulting from the optional 3/2 bit overload procedure
5.9.7 Pre-assigned BCs
6 DCME transmit unit
6.1 Transmit channel processing function
6.1.1 DCME transmit unit initialization
6.1.2 Intermediate trunk classification
6.1.3 Input preprocessing
6.1.4 Service request implementation
6.1.5 Refreshment message generation
6.1.6 ADPCM encoder control
6.1.7 Bit bank handling and overload channel creation
6.1.8 Connectivity implementation delay
7 DCME receive unit structure
7.1 Receive channel processing function
7.1.1 DCME receiver unit initialization
7.1.2 Input pre-processing
7.1.3 Connectivity map update
7.1.4 ADPCM decoder connection control
7.1.5 Bit bank handling and overload channel derivation
7.1.6 Connectivity implementation delay
7.1.7 TCP and TCH interactions
8 On-demand 64 kbit/s circuit handling
8.1 Overview of establishment and disestablishment of 64 kbit/s unrestricted class connections (transparent circuit...
8.2 Transparent circuit handler (TCH)
8.2.1 External information elements
8.2.2 DLC information elements
8.2.3 Other information elements
8.3 On-demand circuit establishment
8.3.1 Normal circuit establishment
8.3.2 Unsuccessful circuit establishment
8.4 On-demand circuit disestablishment
8.4.1 Normal circuit disestablishment
8.4.2 Unsuccessful circuit disestablishment
8.5 Dual seizure handling
8.5.1 Dual seizure condition
8.5.2 Dual seizure resolution
8.6 Spurious disconnect handling
8.6.1 Spurious disconnect conditions
8.6.2 Spurious disconnect recovery
9 Dynamic load control
9.1 Overview
9.1.1 DLC activation/deactivation criteria
9.1.2 Message processing and routing
9.2 Load condition calculation (see Note)
9.3 Voice/voice-band data DLC
9.3.1 DCME function
9.3.2 SCI function
9.4 On-demand 64 kbit/s DLC
9.4.1 DCME function
9.4.2 SCI function
10 Test procedures
10.1 Channel check procedure
10.1.1 Test procedure
10.1.2 Reporting test results (remote DCME)
10.1.3 Reporting test results (local DCME)
10.1.4 Test vector sequence characteristics
10.1.5 Channel check test vectors
10.2 Internal tests
11 Control channel (CC)
11.1 CC error protection
11.2 CC synchronization
11.2.1 Unique word pattern
11.2.2 Unique word detection
11.3 CC message structure
11.3.1 BC identification word
11.3.2 IT identification word
11.3.3 Data word
11.3.4 CC structure when USM option is used
12 Activity detection and data/speech discrimination
12.1 Transmit activity detector
12.1.1 Threshold and operate time
12.1.2 Hangover control
12.1.3 Interaction of transmit activity detector with echo control devices
12.2 Data/speech discriminator
12.2.1 Output conditions
12.2.2 Accuracy
12.2.3 Response time
12.2.4 2100 Hz tone detector
12.3 Signalling detector
12.3.1 Accuracy
12.4 Receive activity detector
13 DCME synchronization and echo control
13.1 DCME synchronization
13.1.1 Reference clock
13.1.2 Plesiochronous slips
13.1.3 Buffer sizes and locations
13.1.4 Terminal synchronization
13.2 Echo control
14 ADPCM encoders and decoders
15 Operations and maintenance functions
15.1 Configuration of the DCME for operation in a network
15.2 System management functions
15.2.1 Transmission facilities
15.2.2 Terminal traffic handling performance
15.2.3 System statistics measurement
15.3 Synchronizer
15.4 Communication links
15.5 Reports
15.6 System configuration
15.7 Failure protection strategy
15.8 Coordinated traffic rearrangements
15.9 Voice orderwire (VOW)
15.10 In-service monitoring
15.10.1 Continuous BER measurements
15.10.2 Channel check procedure
15.10.3 Test port
15.11 Fault conditions and consequent actions
15.11.1 Normal traffic carrying operating conditions
15.11.2 Fault conditions (see Note)
15.11.3 Explanation of consequent actions
15.11.4 Alarm considerations specific to R2D line signalling
16 Glossary
ANNEX A … Examples of DCME transmit/receive unit structure and SDL diagrams
A.1 An example of a DCME transmit unit structure
A.1.1 Transmit Channel Processing Function
A.2 An example of a DCME receive unit structure
A.2.1 Receive Channel Processing Function
ANNEX A.3
A.3 An example of DCME SDL diagrams
A.3.1 Logic diagrams for DCME transmit side
A.3.2 Logic diagrams for DCME receive side
ANNEX B
B.1 An example of a DLC double averaging technique
B.2 Transmit activity detector threshold and operate time characteristic
B.3 Data/speech discriminator
B.3.1 Output conditions
B.3.2 Accuracy
B.3.3 Response time
B.3.4 2100 Hz tone detection
B.4 2400 Hz tone detector
B.5 Speech detector/echo control device interactions
B.6 Timing synchronization
B.6.1 Point-to-point operation
B.6.2 Multi-clique operation
B.6.3 Multi-destination operation
B.7 Performance
B.7.1 Speech performance (provisional)
B.7.2 Voice band data performance
DCME TUTORIAL
1 Use of digital circuit multiplication system (DCMS)
2 Location
3 Transmission requirements
4 DCME gain (DCMG)
5 ISDN bearer services
6 Restoration of services
7 Control of transmission overload
8 Transmission link performance monitoring
References
DCME DIMENSIONING METHODS FOR DIFFERENT ROUTE CHARACTERISTICS
1 Introduction
2 Route profiles
3 DCME operation
3.1 DSI gain for voice
3.2 DSI gain for data
3.3 LRE gain for voice
3.4 LRE gain for data
4 Calculation of DCME gain
4.1 Limitations
4.2 Example gain calculations using simplified techniques
4.2.1 DCME dimensioning using the profile of a route without silence elimination
4.2.2 DCME dimensioning using the profile of a route with silence elimination
4.3 Two pitfalls for the unwary
5 Conclusion