Transcript No Slide Title

Summer school
Jukka Heikkilä
Professor, vice dean
The faculty of Information Technology
University of Jyväskylä
P.O. Box 35
FIN-40351 JYVÄSKYLÄ
FINLAND
tel:+358 50 581 8361
email: [email protected]
Alternative techs
TETRA
Stg in between
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Quick connection
– to a limited number of users
vs. broadcast?
vs. pont-to-point?
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High security (3 levels)
– from authentication to end-to-end encryption
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Open std for application developers (cost)
Access to other systems via gateways
– voice + data
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DMO (direct mode operation)
– outside the radio coverage of BTS
– have mechanisms for roaming control
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Market Position of Technologies
(Toikkanen, 1999)
Increasing
Information
Importance
Increasing
User Base
Organisation
Centred
Communication
PMR
TETRA
Cellular - GSM
Fixed Telephony
Management
Tool
Individual
Centred
Communication
Intro
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What makes TETRA unique
(Toikkanen, 1999)
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Unique group communication package in total
Fast call set-up time
Direct Mode (DMO)
Queuing of channel resources
Signalling during voice call
Pre-emptive priorities, ambience listening
Multiple security schemes & algorithms
– authentication of radios (& networks)
– air interface & end-to-end encryption
– disabling of stolen radios
Brings harmonised PMR spectrum to Europe
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Device manufactures are
committed to the standard set
TETRA interoperability demonstration at TETRA
World Congress, 16-18.11.1999, Amsterdam:
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TETRA TDMA
(Blomberg, 1999)
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4:1 TDMA (Time Division Multiple Access)
4 logical channels
25 kHz carrier spacing
Voice calls use one channel
Data calls can use up to 4 channels (multi-slot data)
Voice and Data can be transmitted simultaneously in different timeslots
Four user channels multiplexed
into one 25 kHz carrier
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Tetra bands
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Availability of infrastructure and terminals with
frequency bands:
–
–
–
–
380
410
450
806
÷
÷
÷
÷
400
430
470
921
MHz (Emergency)
MHz (Civil/autohorities)
MHz (Planned)
MHz
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Core TETRA Standards
(Toikkanen, 1999)
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Voice plus data (V+D)
Packet Data Optimised
(PDO)
Direct Mode Operation
(DMO)
Conformance Testing
TETRA Speech Codec
ISI
Air Interface (AI)
Inter-System Interface (ISI)
Peripheral Equipment Interface
(PEI)
Line Station (LS)
DMO
PEI
AI
LS
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Data Communication
Services (Toikkanen, 1999)
7.2kbits/s
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Status service
– efficient, real time
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Short Data service, SDS
28.8kbits/s
user bit
4 3 rate
1 2
36kbits/s
gross bit
rate
– text messaging + application
vehicle
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IP Packet Data
– opens the world of Internet
connectivity
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Circuit Mode Data
– for specialised applications like
video surveillance
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Direct Mode Operation (DMO)
(Lovett, 2000)
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Direct Mode (DM) is direct communication between
two TETRA DM terminals…..
…or several TETRA DM terminals or mobile stations
without the use of a trunking network infrastructure.
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‘Back-to-Back’ DMO
(Lovett, 2000)
1
2
3
4
DMO Air
Interface
1
Slot Structure
2
3
4
‘Frequency Efficient’
mode can use these
timeslots for another
call
Pre-emption
Speech Slot
DMO
Master
DMO
Slave
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Standard API and
Applications (Nouri, 1999)
Applications
Internet
Access
Standard API
Bearer Service
TETRA ADAPTATION
SDS
LAYER
AVL
Proprietary
WAP
SDS
Telemetry
IP Packet
Data
Circuit
Mode Data
TETRA
NETWORK
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TETRA interface standards
(Toikkanen, 2000)
a) available
Air interface
 PSTN, ISDN gateways
 Data network gateway
 Intersystem interface (general, Indiv Call,
Group Call, Mob Mgmt)
 Peripheral Equipment Interface (PEI)
 Direct mode air interface
 Direct mode repeater and gateway
 Lawful interception (phase 1)
 Test specifications for interfaces
b) in drafting
phase
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Intersystem interface
(SDS)
 Lawful interception
(phase 2) ?
 Line Station
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Gardermoen (OSL) PMR users
(Ludvigsen, 2001)
Passanger handling
Flight handling
Car Parking
Deice
PMR
System
Tech. Maintenance
Fire & Rescue dept.
Fuelling
Catering
Gardermoen (OSL) terminals
(Ludvigsen, 2001)
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Total of 770 terminals
– OSL:
250 terminals
– Airlines: 300 terminals
– Other: 220 terminals
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Dispatchers
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–
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De-icing (1)
SAS (1)
Fire brigade/rescue team (2)
IT - department (1)
Technical - department (1)
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Operational experiences at OSL
(Ludvigsen, 2001)
 First TETRA system in operation May 98, limited number of
terminal types and accessories with reduced functionality
 The system proved to be in stable operation from July 99.
Both HW- and SW-upgrades on central equipment and
portables. Facing a new comprehensive upgrade this
summer.
 For critical communications (Tower-to-Ground) the audio
quality on portable terminals is unacceptable to the users
 Complains on size and weight on terminals
 Operational with high availability for 800 users in non-critical
functions
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Milestones in the TETRA standard
(Godfrey, 2000)
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1990:
1991:
1995:
1996:
1997:
1998:
2000:
standardisation start
standard based on TDMA technology
with 4 timeslot and 25 kHz band
standard first phase completed
frequency armonisation in Europe
(CEPT/NATO)
standard second phase completed
first systems installation
presence of 32 TETRA network in 21
countries
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