Subject: [NEXTEL-1] TETRA Factsheet

From: [email-masked]
Date: Sun, 15 Feb 2004 06:22:17 -0500

TETRA Factsheet

1 Introduction

TETRA is a digital, cellular trunked radio system for voice and data
communication. It is
expected that in spite of its considerable complexity, TETRA will allow more
economical
solutions than to date due to its uniform technical basis and large unit
quantities, in addition
to offering a high degree of flexibility.

Digital trunked radio systems are modern radio systems for private and public
professional
radio applications and for emergency radio applications (PMR/PAMR1). Unlike
earlier
conventional analogue fixed-channel systems (a specific radio channel was
allocated to each
service and each user for the whole time), in the case of trunked radio systems
frequencies
are allocated dynamically to individual users and services. It is therefore
possible to fully
utilise so-called trunk gain and to increase spectrum efficiency. In addition,
the quality and
security of radio systems could be considerably improved using digital
technology.
As early as the first half of the 'eighties, initial attempts were being made to
seek appropriate
solutions for digital PMR systems. This step was essential in order to increase
spectrum
efficiency, improve technical reliability and facilitate encryption of the
connection. It was at
this time that the first proprietary digital PMR systems appeared, including
ASTRO and iDEN
(both by Motorola), EDACS (Ericsson), SR 440 (Bosch/Ascom) and Tetrapol (Matra
Communication).
However, the establishment of a uniform standard for digital PMR systems began
only when
manufacturers, administrations and user groups decided within ETSI in 1989 to
draw up such
a standard, designated TETRA. Since then, TETRA has become one of the most
comprehensive standards ever developed by ETSI, comparable only to the
successful GSM
standard for mobile radio systems.

Potential users of trunked radio systems include closed user groups such as
transport
services (taxis, Swiss Federal Railways, haulage companies, etc.), airports,
energy
companies and the emergency services (e.g. police, the fire brigade, ambulance
services,
the army, civil defence, the frontier police, etc.). All these user groups
either have their own
private trunked radio system or use the services of a trunked radio systems
operator. Today,
approximately 90% of professional radio systems are still based on analogue
technology.
Trunked radio systems differ from public mobile radio systems such as GSM or
UMTS
primarily in terms of their faster call set-up, group calls, priority calls,
end-to-end encryption
and the possibility of direct calls from mobile station to mobile station
without a connection
via a base station (this is known as direct mode).

More data:

http://www.bakom.ch/imperia/md/content/english/telecomdienste/factsheets/4.pdf
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