TETRA, also known as Terrestrial Trunked Radio, is a digital mobile radio standard that was first introduced in the late 1990s. It was designed to meet the communication needs of public safety organizations, such as police, fire, and emergency medical services, as well as other mission-critical users in various industries.
In this article, we will provide a technical overview of TETRA, including its architecture, features, and performance characteristics.
TETRA Architecture
The TETRA standard defines a complete end-to-end digital communication system, which includes the following components:
Radio Access Network (RAN)
The RAN is responsible for providing wireless access to TETRA devices. It consists of several base stations, which are connected to a central switching entity called the TETRA core network.
TETRA base stations typically cover a geographic area of several kilometers, and they communicate with TETRA devices using a variety of modulation schemes, including Gaussian Minimum Shift Keying (GMSK), Quadrature Phase Shift Keying (QPSK), and Differential Quadrature Phase Shift Keying (DQPSK).
TETRA Core Network
The TETRA core network is responsible for providing call control, authentication, and other advanced features to TETRA devices. It consists of several interconnected entities, including the TETRA Switching and Management Infrastructure (TSMI), the TETRA Mobility Management Entity (TMME), and the TETRA Authentication and Key Management Entity (TAKE).
The TSMI is the central entity that manages call routing, resource allocation, and other network functions. The TMME is responsible for managing user mobility, including handover between base stations, and the TAKE is responsible for managing security features, such as authentication and encryption.
TETRA Services
TETRA supports a wide range of voice and data services, including group calls, private calls, status messaging, and packet data services. It also supports a variety of advanced features, such as priority calling, emergency calling, and encryption.
TETRA Features
TETRA includes a number of features that make it well-suited for use in mission-critical applications. These features include:
Direct Mode Operation (DMO)
DMO allows TETRA devices to communicate with each other directly, without the need for a base station. This is useful in situations where a base station is not available or when communication is required in a local area, such as a building or a small geographic area.
Trunking
TETRA uses a trunked radio system, which allows multiple users to share the same radio frequency. This is more efficient than traditional simplex or duplex radio systems, which require dedicated frequencies for each user.
Dynamic Grouping
TETRA supports dynamic grouping, which allows users to join and leave groups as needed. This is useful in situations where communication needs are constantly changing, such as in emergency response situations.
Encryption
TETRA supports encryption, which ensures that communication is secure and cannot be intercepted by unauthorized parties. TETRA uses the Advanced Encryption Standard (AES) with a 128-bit key length, which is considered to be highly secure.
Interoperability
TETRA is designed to be interoperable with other communication systems, including analog radio systems and other digital radio standards, such as P25 and DMR. This allows TETRA to be used in a wide range of applications, without requiring the replacement of existing communication systems.
TETRA Performance Characteristics
TETRA is designed to provide high-quality, reliable communication in mission-critical applications. It has a number of performance characteristics that make it well-suited for this type of application, including:
Voice Quality
TETRA provides high-quality voice communication, with a typical Mean Opinion Score (MOS) of 4.0 or higher. MOS is a measure of the quality of human speech, with a score of 1 indicating poor quality and a score of 5 indicating excellent quality.
TETRA achieves this high level of voice quality through a number of techniques, including voice coding, error correction, and noise reduction.
Coverage
TETRA provides reliable coverage in a variety of environments, including urban, suburban, and rural areas. TETRA base stations typically cover a geographic area of several kilometers, and the use of a trunked radio system allows for efficient use of available frequencies.
Capacity
TETRA provides high capacity, with the ability to support a large number of users on a single frequency. This is achieved through the use of a trunked radio system, as well as efficient channel allocation and management techniques.
Interference Rejection
TETRA is designed to reject interference from other radio systems, such as analog radio systems or other digital radio standards. This is achieved through the use of advanced modulation and filtering techniques, as well as the use of frequency hopping.
Latency
TETRA provides low latency, with typical call setup times of less than 1 second. This is achieved through the use of efficient call routing and resource allocation techniques, as well as the use of fast authentication and encryption algorithms.
TETRA Evolution
TETRA has continued to evolve since its initial introduction in the late 1990s. The latest version of the TETRA standard, known as TETRA Release 2, includes a number of enhancements and new features, including:
Enhanced Data Services
TETRA Release 2 includes enhanced data services, with support for higher data rates and more efficient data transmission. This allows TETRA to support a wider range of applications, including video surveillance, telemetry, and remote monitoring.
Multimedia Services
TETRA Release 2 includes support for multimedia services, including video and image transmission. This allows TETRA to support new applications, such as video surveillance and remote monitoring.
Interoperability with LTE
TETRA Release 2 includes support for interoperability with Long-Term Evolution (LTE), which is the dominant cellular communication standard. This allows TETRA to be used in conjunction with LTE in hybrid networks, providing seamless communication across different networks.
Enhanced Security
TETRA Release 2 includes enhancements to security features, including stronger encryption algorithms and advanced authentication mechanisms. This ensures that TETRA communication is highly secure, even in the face of sophisticated attacks.
Conclusion
TETRA is a highly reliable, secure, and efficient communication standard that is well-suited for use in mission-critical applications. It provides high-quality voice communication, as well as a wide range of data services and advanced features.
TETRA continues to evolve, with the latest version of the standard including enhancements to data services, multimedia services, security, and interoperability with other communication standards.
As the communication needs of public safety organizations and other mission-critical users continue to evolve, TETRA is likely to remain an important communication standard, providing reliable and secure communication in even the most challenging environments.
