1. TETRA ARCHITECTURE AND INTERFACES
Dr. M. Nouri
New Technologies Senior Manager
SELEX Communications
&
Chairman of TC TETRA WG4

2. Agenda 1. TETRA Architecture and Standard Interfaces
2. Description of Individual Interface
Network Aspects and Scenarios
Services
Protocols
3. TETRA Standard Gateways
Features
4. Network Management System
5. Control Room Gateway
6. Conclusions

3. Typical TETRA Network 1b 3 1a 6 2 5 4 External Network ManagementBS BS
TETRA
Infrastructure
NMS 6
Another
TETRA
Network 2 .
1. Air interface (AI)
- Trunked Mode
- Direct Mode
2. Inter-system interfaces (ISI)
3. Peripheral equipment interface(PEI)
4. Line station interface (LSI)
5. Gateways to PSTN, ISDN and PDN
6. External Network management interface (ENMI)
7. Control room gateway
Note:: All interfaces/gateways 1 to 5 are standards.
ENMI (6) is a recommendation. Others are proprietary. BS BS BS BS 5
Control
Room
Line Station (Despatcher) 4
PSTN, ISDN
PDN

4. Air Interface (AI) Variants
DMO
AIR I/F
TMO
AIR I/F
PEI
TETRA Voice plus Data (V+D)
- Trunked Mode Operation (TMO)
- Direct Mode Operation (DMO)
Free DMO
Managed DMO
Packet Data Optimised (PDO)
- Originally Narrow-band
- Later Digital Advanced Wireless
Services (DAWS)
- Now PSPP, a joint ETSI-TIA initiative
(Project MESA)

5. TM V+D Air Interface V V D D V D V V D Physical Layer Features
TETRA
Infrastructure
TDMA
FRAME V
Uplink V
TS 1 D D
TS 2 V D
TS 3 V
Amsterdam November 1999
Downlink V
TS 4 D
Physical Layer Features
TDMA Structure
4 User Channels
25 kHz Channel Spacing
36 kbit/s Transmission Rate
/4 DQPSK Modulation
7.2 kbit/s Speech Coding (including error
correction)
TS = Time Slot

6. Half Duplex/Full Duplex
TM V+D AI Services
Speech
Data
Circuit mode
Packet mode
Short data service
Supplementary Services
Call Control
Mobility Management
Security Services •
Speech/Data/SDS –
Individual Call
Group Call (including Broadcast Call) – •
Speech –
Half Duplex/Full Duplex –
Clear/Encrypted •
Packet Mode Data
- Connection Oriented/Connectionless (X.25)
- IP Packet Data (V.4 and V.6) •
Short Data Service
- 16, 32, 64 and 2048 bits packets

7. TM V+D AI Data Rate Capacities (kbit/s)
Number of
Timeslots 1 2 3 4 No
Protection
7.2
14.4
21.6
28.8
Low
4.8
9.6
19.2
High
2.4
BANDWIDTH ON DEMAND
Real-time circuit mode data applications e.g.
- Video
- Slow Scan TV
Increased throughput (or speed) in Packet
Mode applications such as:
- File Transfer
- Data Base Updates
- Internet Access
Bandwidth on Demand: Applications

8. TM V+D AI Protocol Stack
CONTROL PLANE
USER PLANE
Speech
Circuit Mode
Data
Mobility
Management
Packet
Data
Call Control
Short Data
Supplementary
Services MM
CMCE PD
Layer 3
Mobile/Base Link Control Entity
Voice and Circuit Mode Services use the physical layer and the lower MAC
Other services enter via Service Access Points (SAPs) at the top of layer 3
Open Standard APIs (e.g. WAP and others) are defined for seamless access at these access points
Application layers will be accessing the open standard (or proprietary) APIs
On the base station side, the physical layer connection to switching nodes are normally via 64 kbit/s bearers sub-multiplexed with 8 kbit/s channels
Logical Link Control
Layer 2
Medium Access Control
Physical Layer
Layer 1

9. Direct Mode AI Scenarios
1. INDIVIDUAL CALL
2. GROUP CALL 4
NETWORK
NETWORK
AUTHORIZING
MOBILE STATION
Basic
- Individual Call (Half Duplex)
- Group Call/Broadcast Call
Dual Watch
- Monitoring TM control channel when in DM
- Monitoring DM channels when in TM
Managed Direct Mode
- DM communication requires authorization
- Authorization signals emitted periodically
from an Authorizing Mobile Station
3. DUAL WATCH
4. MANAGED DIRECT MODE

10. Direct Mode AI Scenarios (contd.)
REPEATER
GATEWAY
NETWORK
6. DIRECT MODE GATEWAY
5. DIRECT MODE REPEATER
REP/GW/
AUTHORIZING
MOBILE
REP/GW
NETWORK
NETWORK
Repeater –
Type 1A (same frequency for uplink &
downlink, single call)
Type 1B (different frequencies for
uplink & downlink, single call)
Type 2 (supports two simultaneous
calls)
Gateway
- Interconnects DM and TM users
Managed Repeater, Gateway or both
Combined
7. DIRECT MODE REPEATER/ GATEWAY
8. MANAGED REPEATER/ GATEWAY

11. Direct Mode Call Control
DM AI Protocol Stack
CONTROL PLANE
USER PLANE
Circuit Mode Data
Call Control
Intrinsic Services
Speech
Short Data
Direct Mode Call Control
Layer 3
V+D DMO : Services
Data Link Layer
Layer 2 •
Basic services
Physical Layer –
speech (half duplex)
Layer 1 –
circuit mode data (7.2 kbit/s), high &
low protection –
short data service •
Intrinsic services (3 in total), included
at call set-up •
Addressing (including repeater,
gateway) •
Security services

12. Services Supported by ISI
To Other
Regional SCN
To other TETRA Networks
ISI
Regional
To other
Local
SCN
ISI Applications
Legend
SCN: Switching Control Node
NMS: Network Management System
BS: Base Station
Measured System Expansion
Multi-sourcing of the Infrastructure
Interoperability between different TETRA
Systems
Cross-border Roaming
Individual call
Group Call
Mobility Management
Short Data Service
Supplementary Service
Security
To other
Services Supported by ISI

13. Example: ISI Group Call Configuration
CONTROLLING AND
PARTICIPATING
NETWORK
REQUESTING AND
PARTICIPATING
NETWORK
ISI
ISI : Mobility Management
Migration (Individual and Group)
De- Registration (individual)
Group Attachment/Detachment
Linking and Unlinking of Groups
Database Fault Recovery
TETRA Authentication
OTAR for Key Management
PARTICIPATING NETWORK

14. ISI : Protocol Stack ISI Physical Layer based on Digital 64 kbit/s
TETRA INFRASTRUCTURE 1
TETRA
INFRASTRUCTURE 2
ton
TETRA ANF
TETRA ANF
Specific TETRA Operation
c TETRA operation
Specific TETRA Operation
ITU-T Rec. X.229
ISI
ITU-T Rec. X.229
ISO/IEC 11582
ISO/IEC 11582
ISO/IEC 11572
ISO/IEC 11572
ETS and 2
ETS and 2
Physical Layer based on Digital 64 kbit/s
Connection
TETRA Voice Coding maintained
User Information encoded as 8 kbit/s
N x 8kbit/s Multiplexing according to ITU
Rec. I. 460
Higher layers according to PSS1 (Q.Sig.)
standard
Layer 1
Layer 1
PRIVATE SIGNALLING SYSTEM 1 (PSS1) USED IN ISI STANDARD

15. IP Inter-working Interface
Host
Packet Data Network
IPI
Inter-Network Backbone Gi Gp Gi
GGSN BG BG
GGSN Gn Gn
Internal Backbone
Internal Backbone
ISI
IP Inter-working (IPI) plus roaming support between two TETRA networks is based on GPRS Tunneling Protocol
Standard GPRS interfaces Gp, Gn and Gi are used for inter-working directly or via a third IP network
Roaming profile is supplied through ISI between home and visiting databases
BG is the Border Gateway providing Gp with security functions
TETRA SNDCP* sub-layer and the Gateway GPRS Support Node (GGSN) provide IMSI-ITSI association
* SNDCP: Sub Network Dependent Convergence Protocol
HDB
VDB
HDB
VDB
TETRA
Infrastructure 1
TETRA
Infrastructure 2

16. Peripheral Equipment Interface (PEI)
MT2
TE2
TETRA
INFRASTRUCTURE
Services offered by PEI
Set-up & Communication
- Packet Data
- Circuit Data
- Short Data
Set-up & Control
- Speech Calls
Access to:
- Data on MT2 & Infrastructure
- User Applications on MT2
PEI

17. Access Services through PEI Protocol Layers
APPLICATIONS AT
TNP1 PD
Circuit
Mode Data
UDP/IP IP
Three access services are defined across the PEI
AT (attention) Commands are used to access & control
Circuit Mode Data Service, Short Data Service and Radio
Configuration
TNP1, TETRA Network Protocol 1, allows remote handling
of Circuit Mode Control Entity (CMCE), Radio
Configuration via UDP/IP and PPP layers
Packet Data Service is accessed directly via IP layer on
top of PPP platform
Physical Layer: ITU-T V.24/V.28 with speeds
normally < 20 kbit/s (up to 115 kbit/s possible)
Access Services through PEI Protocol Layers
PPP
V. 24/V. 28
TO MOBILE STATION

18. Standard API and Applications
Internet
Access
AVL
Telemetry
Standard API
WAP
Proprietary
Bearer Service
IP Packet
Data
Circuit
Mode Data
SDS
TETRA ADAPTATION
LAYER
Data Application Examples
Data base interrogation/updates (p,s)
File transfer (c,p)
Messaging/paging (p,s)
Vehicle location (p,s)
Telemetry (p,s)
Video transmission (c)
Image transfer/graphics (c,p)
Computer aided despatch (p,s)
Mobile office (c,p,s)
Network

19. IP and TETRA Network Wide selection of IP applications via:
Content
Provider
Network Management
System
WAP
Terminal IP
WAP GW
Internet
Database
LAN
Server IP IP
Corporate
Intranet
IP Switching/
Routing Network IP IP
GPS
Bluetooth IP
Wide selection of IP applications via:
- Data terminal connected to handset
- PEI (wired or bluetooth connection)
- WAP enabled handset and micro-browser
- Dispatcher terminal
Standard APIs for a range of applications
- WAP for internet / intranet applications using WML
- AVL for location dependent applications
- Others
Two network concepts:
- IP over TETRA (circuit switching and packet routing)
- TETRA over IP (use of packet routers only)
Control
Room
Server IP
TETRA Infrastructure IP
Voice/IP
Dispatcher

20. PSTN Gateway PSTN PSTNGW Clear Mode Speech (Point-to-Point or
Point-to-Multipoint)
Maintenance of Signalling across the Gateway
Echo Cancellation (Full-Duplex)
Request to transmit from PSTN or Voice
Detection Device (Half-Duplex)
TETRA Codec Function
Numbering Conversion
No Interaction with Supplementary Services

21. ISDN Gateway ISDN 2B+D 30B+2D ISDNGW
Matching TETRA signalling and ISDN DSS1
signalling
Addressing a TETRA user from ISDN using two
stage dialling or via ISDN supplementary services
Primary and basic rate (not multiple gateways on
the same basic rate bus)
Circuit mode data not part of this standard
Request to transmit from ISDN or voice detection
device (half duplex)
Partial invocation of TETRA and ISDN supplementary
services across the gateway
Trans-coding and rate adaptation to 64 kbit/s PCM

22. Network Management (1) (Internal)
Authentication
Centre
NMS Client
LAN
SCN
Server
Disks
21”
15”
NMS
ROUTER
Client
Internal network Management System caters for monitoring and control of a TETRA network whether single site or national in extent.
External network management is applied to two or more TETRA networks connected by ISI.
Due to a flexible infrastructure policy, no attempt was made at Project TETRA to standardise Internal NM architecture and interfaces.
Many concepts, architectures, interfaces and protocols such as TMN, CORBA, CMIS/P, SNMP, DiffServe and others have been defined by standardisation bodies for NM. The choice depends on infrastructure details.
However, Project TETRA has defined a simplified external NM scheme as a recommendation, now incorporated in the Designer’s Guide.

23. Network Management (2) (external)
TETRA 1
ISI
TETRA 2
NMS
NMS
ISI
ISI
TETRA 3
NMS
Types of NM Functions
Performance Management
Fault or Maintenance Management
Subscriber Management
Accounting Management
Security Management
External Management of more than 1
TETRA system
Primarily a monitoring role
Only a sub-set of NMS functions
Interoperability between different
manufacturer’s NMS
Management of ISI and inter-TETRA
links
Management of wide area roamers
ENM

24. Control Room Gateway (1)
GSM
Internet
GPS
Databases
ICCS
Corporate
Intranet
Control
Room
Gateway
Internet
Server
AVL Controller
Dispatchers
TETRA
The flexibility to incorporate:
PSTN / ISDN
IT System
Call Logging
CCTV
Paging
Fax /
Voice Recording
Others
Telephony
Radio UHF/VHF, TETRA
Voice Recording
Call Logging
Interactive Voice
Response
Intercom
Public Address
CCTV
The Future….
Legacy
Radios
Paging
GSM
Voice Over IP
PSTN Call Routing and
Voice Messaging
Electronic Communication
, Fax, Chat
Ancillary Devices
Databases & IT Systems

25. Control Room Gateway (2)
Not standardized because of different applications
requirements from different user sectors
Current trend is to include Flexible Application
Programming Interfaces (APIs) to facilitate
communication with the API client
Management of following functionalities through
API using API libraries or through messages :
Audio parameters
Individual and Group Users
Supplementary services
Alarms
To control room application client
API Client
Application
Server
TCP/IP link to control room application client
Standard APIs with own libraries usually implemented in Windows or Unix
Flexible APIs used to:
- Facilitate Programming at a higher abstraction level
- Allow integration of radio functionality in different systems
- Guarantee flexibility of control center configuration
- Allow GUI’s customization
Gateway
Engine
To TETRA Switch Interface

26. Conclusions TETRA Architectures and Interfaces allow:
Spectrally-efficient feature rich communication
Choice of trunked or direct modes
Interoperability between different TETRA networks
Multimedia services and Internet access
Extensive data applications capability
Inter-working with public networks
Use of control room gateways in public safety and other sectors