Tutorial on TETRA Radio System Basics
This TETRA Radio System tutorial covers Trunk radio communication system or trunking radio basics. It mentions what is TETRA, TETRA interfaces, TETRA frequency bands, TETRA frame structure and TETRA standard references.
What is TETRA
TETRA is the short form of Trans-European Trunked Radio System. It is digital private mobile radio standard defined by ETSI.
TETRA mobile user can communicate to other users via base station or directly. TETRA user can be assigned one time slot or 4 time slots as transmission bandwidth. These 4 channels can be modulated over one RF carrier frequency. All the carriers are of 25KHz Bandwidth.
As the major application of TETRA trunk radio system is public safety as well as emergency services; call set up time should be less. Hence TETRA radio is designed to provide set up time of about 300ms. TETRA radio system supports semi duplex operations for group communication. It supports duplex operation for individual telephone calls. TETRA radio uses π/4 DQPSK modulation scheme. It has maximum transmission rate of about 36 Kbps. As mentioned RF carrier spacing is about 25KHz. RF frequency duplex spacing is 10MHz (45MHz is in 900 MHz frequency band). The TETRA frequency bands are mentioned below.
TETRA Network Interfaces
The fig-1 mentions the various TETRA network interfaces. As shown TETRA network consists of Air interface, Terminal Equipment Interface (TEI),
Direct Mode Operation(DMO) and Inter-System Interface (ISI).
1. Air Interface ensures the interoperability of terminal equipment from different manufacturers.
2. TEI facilitates the independent development of mobile data applications.
3. ISI allows the interconnection of TETRA networks from different manufacturers.
4. DM0 guarantees communication between terminals also beyond network coverage.
TETRA Frequency bands
TETRA Voice+Data works on VHF of 150MHz and UHF of 900MHz frequency bands.
The other TETRA frequency bands have following frequency values.
• 410MHz-420MHz, 420MHz-430MHz
• 450MHz-460MHz, 460MHz-470MHz
• 870MHz-888MHz, 915MHz-993MHz
TETRA Frame Structure
The fig-2 depicts the TETRA frame structure. As mentioned TETRA frame is basically TDMA frame. Each frame composed of 4 time slots. About 18 such TDMA frames form one multi-frame. Total 17 frames are used for carrying information data and 1 frame (i.e. 18th frame) is used as control frame. This 18th channel is used as SACCH (i.e. Slow Associated Control Channel) to carry control channel signalling. The 60 such multi-frames will make 1 hyperframe of this TETRA Radio System or Trunk radio communication system. As mentioned time slot is the lowest unit of allocation which is made of 510 modulating bits.
1 TETRA Time Slot duration = 14.167 ms
1 TETRA frame duration = 56.67 ms
1 TETRA multi-frame= 1.02 second
1 TETRA hyperframe = 61.2 second
Similar to GSM slot, TETRA slot structures are of 3 types viz. uplink half slot, uplink full slot and
downlink full slot. This slot structures carry five different types of physical bursts.
These different bursts are transmitted over TETRA air interface as outlined above.
• Normal Downlink(Half time slots for random and reserved access)
• Synchronization Downlink(Full Slot used by mobile stations after the initial entry to the system)
• Control Uplink
• Normal Uplink
• Linearization Uplink
TETRA Standard References
Following table lists out ETSI references to TETRA standards for various applications.
| TETRA Voice Plus Data | ETS 300.392 |
|---|---|
| Part 1 | General Network Design |
| Part 2 | Air interface |
| Part 3 | Inner Working |
| Part 4 | Gateways |
| Part 5 | Terminal Equipment Interface |
| Part 6 | Line Connected Stations |
| Part 7 | Security |
| Part 8 | Network Management Services |
| Part 9 | Performance Objectives |
| Part 10 | Supplementary Services Stage 1 |
| Part 11 | Supplementary Services Stage 2 |
| Part 12 | Supplementary Services Stage 3 |
| Part 13 | SDL Model for Air interface |
| Part 14 | PICS |
| TETRA Packet Data Optimized(PDO) | ETS 300.393 |
|---|---|
| Part 1 | General Network Design |
| Part 2 | TETRA Air interface |
| Part 3 | Inter working |
| Part 4 | Gateways |
| Part 5 | Terminal Equipment Interface |
| Part 6 | Line connected stations |
| Part 7 | security |
| Part 8 | network management services |
| Part 9 | performance objectives |
| Part 10 | SDL model for air interface |
| Part 11 | PICS performa |
| TETRA CODEC | ETS 300.395 |
|---|---|
| Part 1 | General speech function description |
| Part 2 | Codec |
| Part 3 | specific operational features |
| Part 4 | Codec conformance testing |
| TETRA Direct Mode Operation(DMO) | ETS 300.396 |
|---|---|
| Part 1 | General network design |
| Part 2 | Direct MS to MS radio interface |
| Part 3 | Repeater |
| Part 4 | Gateway |
| Part 5 | Security |
Difference between TETRA and TETRA2
Difference between TETRA and TETRA2 system
Other Digital Radio and Analog Radio Systems
TETRA Radio System
Difference between TETRA and TETRA2 system
APCO-25 versus APCO-16
Opensky Radio System
DMR-Digital Mobile Radio
iDEN-Integrate Digital Enhanced Network
Useful frame structures
16d 16e WiMAX Frame Structure Zigbee frame GPS Frame Structure LTE Frame Structure UMTS Frame Structure SDH Frame Structure 802.11ac PHY Frame Structure WLAN Frame GSM Frame
RF Wireless Tutorials
What is?
what is wlan? what is wimax? what is lte? what is RF? what is wireless ? what is zigbee? what is lightwave RF? what is z-wave? what is GSM? what is CDMA? what is GPRS?