TETRA Radio Systems

MOBILE RADIO TETRA radio systems

TETRA – the digital standard for professional mobile radio

TETRA, the worldwide digital standard TETRA – an open standard TETRA. The sophisticated and thorough voting procedure ensured the standard’s for professional mobile radio, offers At the start of the 1990s, the European high quality and functionality for profes- Telecommunications Standards Institute sional mobile radio users, which cannot excellent speech quality, high data (ETSI) was commissioned by the EU to be achieved by proprietary technologies. create a European standard for profes- TETRA has meanwhile been introduced transmission rates and secure, encrypt- sional digital radio. The most important on all continents and like GSM is well on parts of the TETRA standard (terrestrial the way to becoming a world standard. able connections. trunked radio) were adopted at the end of 1995 in national votes. NATO in the past released one of its frequency bands – 380 MHz to 400 MHz – The influence of users on the devel- and made it available to European NATO opment of TETRA can be clearly seen. countries for use by government author- Government authorities and organiza- ities and organizations with security mis- tions with security missions in particu- sions. The European TETRA standard and lar have worked together intensely to the harmonized frequency bands make it See page 6 for ACCESSNET®-T, the achieve standardization. Specifically, the possible for the first time to implement a digital TETRA mobile radio system compatibility required by the Schengen Europe-wide public safety network. from Rohde & Schwarz. agreements is not possible without an approved European standard such as Features of professional mobile radio systems

The most important requirement for mobile radio networks for professional use is availability and security against eavesdropping. Secure physical connections are based on proper technical plan- ning of the network but also on the pos- sibilities offered by the standard. For instance, the handover specified in the TETRA standard ensures that a call can continue smoothly even when moving from one cell to another.

Security against eavesdropping is attained by encryption. For this pur-

News from Rohde&Schwarz Number 178 (2003/II) TETRA … world standard with many advantages:

Fast data transmission Outstanding cost efficiency TETRA provides 7.2 kbit/s on a com- The open TETRA standard ensures fair pose, the TETRA standard also contains munication channel. If necessary, competition. Industry’s broad support specifications that define the encryption up to four channels can be banded, of TETRA allows users to choose from a of the air interface and/or end-to-end increasing the data rate to as high as large number of companies at reason- encryption, for instance. 28.8 kbit/s. Currently work is under- able prices. way to enhance the standard for even In emergencies, quick call setup in higher transmission rates. Secure cooperation a public safety network is essential, Cooperation between different types of because every second counts. The call Diverse interfaces radio networks is becoming more and setup time in a TETRA radio cell is there- To ensure a standard that is open and more important. TETRA networks make it fore ≤300 ms. used by many manufacturers, TETRA possible to have a large number of con- defines the following basic interfaces: nections to external communication net- Another important feature of profes- The air interface establishes compat- works. For instance, TETRA networks sional mobile radio networks, and pri- ibility between terminals of different can be connected with public and pri- marily of public safety networks, are manufacturers. vate telephone networks, different kinds the group-call functions, since the over- The device interface guarantees the of data networks and also with large whelming majority of communication independent development of mobile command and signalling networks. All between users is via group calls. The radio applications. these networks can be accessed from head of a police or fire-department The intersystem interface (ISI) allows mobile radios. Virtual networks within squad does not inform each squad the connection of TETRA networks of the TETRA radio network ensure that member individually but passes the different manufacturers. every organization can work indepen- information on to everyone involved at The direct mode ensures secure com- dently without requiring its own infra- the press of a button. munication when exiting the cov- structure and without having to give ered area, enabling direct radio traf- up the advantages of a large multifunc- TETRA systems provide radio connec- fic between mobile radios without the tional system with efficient resource tions in all conceivable forms. They need of a network infrastructure. management. support voice communications (single, group and announcement call), data Interfaces to wired communication net- Open for applications transmission (circuit mode data and works are also standardized, leaving The open interfaces allow users to create packet mode data) and short data ser- only the design of the interfaces within applications or to have them created. vice using a wide range of data trans- the infrastructure up to the manufac- A lot can be planned and taken into mission rates and error-protection levels. turers. Standardization makes for fair account in advance except, of course, TETRA employs TDMA (time division competition, but gives third parties one thing – a fully turnkey solution for multiple access) technology with four the freedom to implement economical a communication network. The open- integrated communication channels at solutions for applications. ness of the TETRA standard, however, 25 kHz channel bandwidth. will help users get closer to their ideals, Harald Haage since it provides room for new applications and enhancements.

5 News from Rohde&Schwarz Number 178 (2003/II)