TETRA network availability is critical to ensure mission-critical communications. TETRA networks are designed to fulfil very high availability levels – typically between 99.95 to 99.999% for operation of TETRA core and access (base station) components.
This level of availability can only be achieved by using redundancy in order to protect against equipment failures. The status of the redundant components must be kept synchronised with the active components to allow instant failover without the intervention of the network operator.
Battery backup and component redundancy can also be included in the base station design in order to improve availability. Furthermore, coverage redundancy by overlapping base station sites may be considered in the network design to further enhance availability.
In addition to equipment redundancy, link redundancy to the base station must also be considered. Link redundancy is essential to achieve high network-wide coverage availability, important for TETRA radio users to stay in contact with the control room and other TETRA radio users outside the coverage area of the base station.
As a last resort, TETRA base stations support local fallback mode, allowing TETRA radio users to continue communication within the base station coverage area when no links are available to the core infrastructure. Specific TETRA features are developed to give base stations with network-wide coverage priority above isolated ones.
TETRA networks are designed and built to fulfil these critical availability requirements, and TETRA network operators have full control in order to benefit from these high availability solutions.
When dealing with public safety and security critical communications, time is of the essence; instant reactions in emergencies are crucial as even a small delay can mean the difference between life and death. Similarly, within business and industrial critical communication, instantly available communication and information is vital to ensure a minimum of downtime and thereby a minimum of economic losses.
With instant communication at its core, TETRA is built for such situations. Call setup is immediate, and important calls can be given pre-emptive status to ensure timeslot availability. Furthermore, the caller is given instant visual and audible feedback in case the called party is unreachable or busy.
Likewise, SDS messages are delivered instantly so can also be used for emergency purposes. The instant SDS feature enables real-time tracking of mobile devices and on-the-spot DGNA group creation, making it possible to deliver a fast and accurate response to emergencies in the field.
TETRA instantly provides comprehensive and accurate voice and data recording facilities and a wide range of logging facilities for CDR, enabling fast and easy incident reconstruction and traceability. Among other things, this means immediate access to voice recordings for playback, eliminating the need for additional clarifying calls in life-critical situations where time is of the essence.
A TETRA system is up and running as soon as the power is switched on. In case of operational failure, there is a built-in automatic recovery system supporting switchover to hot standby components or graceful degradation of the system in order to maintain instant communication.
Communication security is an essential prerequisite for the success of critical operations.
The protection against eavesdropping and manipulation of voice and data as well as the exclusion of third-party use are therefore indispensable requirements for critical communication systems. This is particularly true against the background of increasing cybercrime.
TETRA’s security features, developed by critical communication experts, are modular and complement each other to meet the security requirements of critical applications. They are an integral part of the standard and thus guarantee security even when using devices and infrastructure from different manufacturers.
The TETRA standard supports powerful mutual authentication of a device on the one hand and the network on the other. This makes it possible for a TETRA system to control the access to it and for a device to check if a network can be trusted. In addition, applications enable authentication down to the user level.
If a device is lost or stolen it is fundamental in a critical environment to exclude this device from using the network. TETRA supports different options for a direct secure disabling over the air. The disabling can be either temporary, which leaves the possibility to enable again, or permanent which is irreversible.
As any air interface is very vulnerable to eavesdropping, TETRA provides air interface encryption where user and signalling information is encrypted over the air interface between devices and infrastructure, both for individual and group communications. The air interface encryption mechanism is available for voice and data and direct mode operation. The use of several encryption algorithms, both standard and proprietary, also is supported.
End-to-end encryption service can be realised in TETRA in any number of ways. This means that a user organisation may easily tailor an end-to-end encryption system to its own requirements. This flexibility is essential and unique in TETRA, which can be implemented in many forms for different user groups.
The security management features of TETRA allow the user organisation to control, manage and operate the individual security mechanisms. They form the heart of the security and guarantee that the security features are integrated into a consistent security system. As key management is the most essential security management function, a large number of features are integrated to support it. The TETRA standard security mechanism will be regularly enhanced to guarantee secure communication to 2035 and beyond.
In addition the all-IP design of TETRA networks enables the use of state-of-the-art external protection devices such as firewalls.
TETRA networks are able to operate either completely stand alone, i.e. disconnected from the Internet, or integrated into the user organisations’ communication and IT environment, which enables the use of the protection mechanism of the organisation against cyberattacks and other threats.
TETRA devices are equipped with closed and secure operating systems, which complete the leading edge TETRA system security.