Digital Mobile Radio

Introduction

Analogue Private Mobile Radio (PMR) has enjoyed great success in Europe for many years, and serves a very broad community of users. Available for both licensed and unlicensed spectrum use, PMR applications extend from low-cost walkie-talkies aimed at the consumer market through to public safety and mission-critical systems. A comparable technology known as Specialized Mobile Radio (SMR) exists in the United States.

Changes to the professional environment have meant that the operational requirements placed on communication equipment have evolved, and the traditional analogue service is no longer able to meet the users' needs completely. A demand for more sophisticated services has raised a need for a technology enhancement and inevitably this has led to a redefinition of PMR based on digital technology.

Our Role & Activities

A direct replacement for analogue PMR

Digital Mobile Radio (DMR) is a new European standard, produced by ETSI, defining a direct digital replacement for analogue PMR. The PMR/DMR markets can be roughly divided into three broad categories. DMR has the capability to serve them all:

  • Consumer and short-range industrial
  • Professional / Business-Critical applications
  • Public Safety / Mission-Critical applications.

DMR is a scaleable system that can be used in unlicensed mode (in a 446.1 to 446.2 MHz band), and in licensed mode, subject to national frequency planning. It is developed in three 'tiers':

  • Tier 1 is the low-cost, licence-exempt 'digital PMR446'
  • Tier 2 is for the professional market offering peer-to-peer mode and repeater mode (licensed)
  • Tier 3 is for trunked operation (licensed).
The technology promises improved range, higher data rates, more efficient use of spectrum, and improved battery. Significantly, DMR has been designed to fit into existing licensed PMR bands, meaning that there is no need for rebanding or relicensing, thus aiding the transition from analogue to digital. The new standard imposes no fundamental changes in the architecture of either conventional or trunked systems - the focus is on a change in the over-the-air protocol that will facilitate the use of applications that are beyond the capability of analogue schemes.
 
Features supported include fast call set-up, calls to groups and individuals, short data and packet data calls. The communications modes include individual calls, group calls, broadcast calls and, of course, a direct communication mode among the mobiles. Other important DMR functions such as emergency calls, priority calls, full duplex communications, short data messages and IP-packet data transmissions are supported.

An alternative to TETRA

For business users, DMR may be seen as a commercially attractive alternative to TETRA, particularly for those users who do not need (or cannot afford) the complexity of this highly-successful digital technology. Many existing digital radio protocols suffer reduced radio coverage so a swap-out from analogue FM to digital is not possible. DMR has been specifically designed to offer at least the same range as 12.5kHz channel analogue FM so a direct replacement or upgrade from analogue to DMR is a practical proposition.

Narrow-band option

DMR tier 1 equipment on the market is often combined with analogue PMR 446, to provide 16 digital and 8 analogue physical channels at 446 MHz and, with privacy coding, even more logical channels. A new harmonized 446.1 - 446.2 MHz licence-exempt band is being opened up by several European countries over the next few years.
 
In order to help maximize the capacity of that allocation, ETSI has defined a narrow-band digital radio protocol for this band: 'digital PMR' which utilizes 6.25 kHz channel FDMA (Frequency Division Multiple Access). This protocol provides for consumer and low-power commercial applications using a maximum of 500mW e.r.p (effective radiated power).

ETSI Standards

ETSI Technical Report TR 102 398 provides a useful introduction to DMR. Technical Specification TS 102 362 parts 1 to 3 covers DMR protocol conformance testing and test suites, and Technical Specification TS 102 490 defines the narrow-band or 'digital PMR' protocol.
 
System Reference Documents produced by ETSI have enabled the European frequency administrations to agree on the harmonized license-free use of digital PMR 446 (meaning that the same frequencies are, or will be made, available in all European countries). The System Reference Documents are ETSI Technical Report TR 102 335-1 (Tier 1 DMR) and TR 102 335-2 (licensed).

 


Standards

The following is a list of recently published and frequently downloaded standards. Please use the ETSI Work Programme to find further related standards.

Standard No. Standard title.
TS 102 658 Electromagnetic compatibility and Radio spectrum Matters (ERM); Digital Private Mobile Radio (dPMR) using FDMA with a channel spacing of 6,25 kHz
TS 102 490 Electromagnetic compatibility and Radio spectrum Matters (ERM); Peer-to-Peer Digital Private Mobile Radio using FDMA with a channel spacing of 6,25 kHz with e.r.p. of up to 500 mW
TS 103 236 Electromagnetic compatibility and Radio spectrum Matters (ERM); Continuous Tone Controlled Signalling System (CTCSS) and Digitally Coded Squelch Signalling (DCSS) system
TS 102 361-2 Electromagnetic compatibility and Radio spectrum Matters (ERM); Digital Mobile Radio (DMR) Systems; Part 2: DMR voice and generic services and facilities
TS 102 361-3 Electromagnetic compatibility and Radio spectrum Matters (ERM); Digital Mobile Radio (DMR) Systems; Part 3: DMR data protocol
TS 102 361-1 Electromagnetic compatibility and Radio spectrum Matters (ERM); Digital Mobile Radio (DMR) Systems; Part 1: DMR Air Interface (AI) protocol
TR 102 884 Electromagnetic compatibility and Radio spectrum Matters (ERM); digital Private Mobile Radio (dPMR) General System Design
TR 102 398 Electromagnetic compatibility and Radio spectrum Matters (ERM); Digital Mobile Radio (DMR) General System Design
EN 301 166-1 Electromagnetic compatibility and Radio spectrum Matters (ERM); Land Mobile Service; Radio equipment for analogue and/or digital communication (speech and/or data) and operating on narrow band channels and having an antenna connector; Part 1: Technical characteristics and methods of measurement
EN 301 166-2 Electromagnetic compatibility and Radio spectrum Matters (ERM); Land Mobile Service; Radio equipment for analogue and/or digital communication (speech and/or data) and operating on narrow band channels and having an antenna connector; Part 2: Harmonized EN covering essential requirements of article 3.2 of the R&TTE Directive
TR 102 433 Electromagnetic compatibility and Radio spectrum Matters (ERM); Digital Private Mobile Radio (DPMR) using a channel spacing of 6,25 kHz and operating in specified VHF and UHF bands under general authorization without individual rights; System reference document
TS 102 362-1 Electromagnetic compatibility and Radio spectrum Matters (ERM); Conformance testing for the Digital Mobile Radio (DMR); Part 1: Protocol Implementation Conformance Statement (PICS) proforma
TS 102 362-2 Electromagnetic compatibility and Radio spectrum Matters (ERM); Conformance testing for the Digital Mobile Radio (DMR); Part 2: Test Suite Structure and Test Purposes (TSS&TP) specification
TS 102 362-3 Electromagnetic compatibility and Radio spectrum Matters (ERM); Conformance testing for the Digital Mobile Radio (DMR); Part 3: Abstract Test Suite (ATS)