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Two-way Radio: Digital Technologies

15 Aug. 2016   Information

APCO-25
APCO-25 (Association of Public Safety Communication Officials – Project 25) is an open standard for digital radio developed in North America under state, local and federal representatives and Telecommunications Industry Association (TIA) governance. The standard was developed to foster the development and progress of the art of public safety communications.

APCO-25 brings together representatives from various associations and agencies to obtain as many contributions as possible to make the resulting specification a world standard for digital land public safety mobile radio. The objective is to find solutions that best serve the needs of the public safety marketplace. In addition, the committee has encouraged the participation of numerous international public safety organizations, making this a worldwide recommended standard-setting initiative. Worldwide interest has been generated due to the standards process being pursued by users working closely with the industry.

Backward Compatibility with Analog
APCO-25 standard allows backward compatibility with analog system. APCO-25 radio can directly interoperate with analog radios that are using the same frequency (note: direct interoperation here means direct communication among radios without using network infrastructure). With this capability, APCO-25 allows some smooth migration from analog system to digital. Users who already own analog system can migrate to digital by phases. Thus, users can decide to upgrade to digital system based on their needs, timing and resources.

Trunked and Conventional in One Network
APCO-25 supports combination of conventional and/or trunked system in one network. This gives user an advantage to have an option to deploy trunked system in high density area and conventional in less density area.

Spectrum Utilization
APCO P25 utilizes Frequency Division Multiple Access (FDMA) techniques to achieve spectrum efficiency. At present, APCO can achieve up to 2 (two) voice channels in one 25 KHz radio channel.
Frequency Band
Frequency bands for APCO-25 products that are typically found in the market today:
Capabilities and Features
From end user point of view, APCO-25 provides, among others:

DMR
DMR (Digital Mobile Radio) is a digital radio standard for Professional Mobile Radio (PMR) users developed by ETSI under its ERM Technical Committee. The standard is designed to operate within the existing channel spacing used in land mobile frequency bands in Europe. DMR is specifically targeted at small to medium sized PMR systems where analogue PMR is currently applied today. The primary goal of the DMR standardization is to specify a digital system with low complexity and low cost levels. It will provide voice, data and other supplementary services.
Learn more about DMR Radio and PMR Radio.

EDACS
EDACS (Enhanced Digital Access Communication System) is a trunked system that is available in both analog and digital air interface. This technology was invented by General Electric Corporation in mids 1980s. This system is based on a number of proprietary interfaces and protocols, for example, the air interface is proprietary as well as the digital vocoder, known as the Aegis Vocoder. EDACS is used in trunked repeater systems that include wide-area simulcast operation.

Spectrum Utilization
EDACS utilizes Frequency Division Multiple Access (FDMA) technique to utilize spectrum. EDACS support both 25 KHz and 12.5 KHz bandwidths. Thus, EDACS can achieve up to 2 voice channel in a 25 KHz radio channel.
Frequency Band
The current available product in the market today offers the following frequency bands:

iDEN
iDEN (integrated Enhanced Digital Network) is a digital trunked radio developed by Motorola which provides its users the benefits of a trunked radio and a cellular-like telephone services. It was first introduced in 1994. The technology supports multiple services in single devices. The Four-in-one service allows business users to take advantage of advanced wireless technologies with one pocket-sized digital handset that combines: two-way digital radio; digital wireless phone; short message services; and data capabilities leveraging Internet access technology.

iDEN places more users in a given spectral space, compared to analog cellular and two-way radio systems, by using speech compression and time division multiple access TDMA. Using these technique, iDEN can achieve 6 time slots in one 25 KHz.

iDEN handsets use SIM cards, just like GSM, and, in fact, the interconnect-side of the network uses GSM signaling for call set-up and mobility management, with the protocol stack modified to support iDEN's additional features. With its sleek and compact form factor, the iDEN handset looks similar to cellular handset. Various handset model are available. The iDEN handset features include color display, built-in GPS, WAP support, ruggedized (for some model), dual mode GSM/iDEN (some model) and other features comparable to cellular handset.

Spectrum Utilization
iDEN is the most spectrally efficient radio technology. iDEN utilizes Time Division Multiple Access (TDMA) techniques to achieve spectrum efficiency. iDEN can achieve up to 6 (six) TDMA time slots in one 25 KHz radio channel.
Frequency Band
At present, iDEN supports frequency band in 800 MHz Band.
iDEN Capabilities and Features
From end user point of view, iDEN provides, among others, the following features and services:

OpenSky
OpenSky is a wireless communication system, developed by a team of M/A-COM Inc., now a division of Tyco International's Electronics unit. OpenSky received the direct attention of Tyco when they acquired it along with Amp Corporation. The technology was originally developed for Federal Express in mid 1990s for its urban operations. The technology was developed to meet the requirement of higher message data speed compared to its previous system. It was initially designed as a wireless data system but the system can support both voice and data services. OpenSky technology applies voice-over-IP transport to radio communications applications in a unique architecture.

Spectrum Utilization
OpenSky utilizes TDMA with 4 (four) time slots to support both voice and data. The four time slots can be used for both voice and data simultaneously or can be aggregated to support 19.2 kbps throughput on a 25 KHz channel.
Frequency Band
Frequency bands for OpenSky products that are typically found in the market today:

TETRA
TETRA (Terrestrial Trunked Radio) is a digital trunked radio standard developed by the European Telecommunications Standards Institute (ETSI). ETSI is a standardization body for Information and Communication Technology in Europe. The purpose of the TETRA standard was to meet the needs of Professional Mobile Radio (PMR) user organizations. The first version of TETRA standard was published in 1995.

Because the TETRA standard has been specifically developed to meet the needs of a wide variety of PMR user organizations, it has a scaleable architecture allowing network deployments ranging from single site - local area coverage to multiple site - wide area national coverage.   Besides meeting the needs of PMR user organizations, the TETRA standard has also been developed to meet the needs of Public Access Mobile Radio (PAMR) operators.

Recognizing that important market requirements outside the responsibility of ETSI needed to be addressed to ensure the success of TETRA, a number of organizations formed the TETRA MoU (Memorandum of Understanding) Association in December 1994.  The main objectives of the TETRA Association are to promote the TETRA standard and to ensure multi-vendor equipment interoperability. This forum acts on behalf of all interested parties, representing users, manufacturers, application providers, integrators, operators, test houses and telecom agencies who are involved in the development and or deployment of the TETRA standard. Today the TETRA Association represents over 135 organizations, from all continents of the world

Spectrum Utilization
TETRA utilizes Time Division Multiple Access (TDMA) technique to achieve spectrum efficiency. TETRA can achieve up to 4 (four) TDMA time slots in one 25 KHz radio channel.
Frequency Band
Frequency bands for TETRA products that are typically found in the market today:
Some vendors have promised to provide some other band to meet requirement in specific market.
TETRA Capabilities and Features
From end user point of view, TETRA provides the following features and services:

TETRAPOL
TETRAPOL is a digital trunked radio solution, originally developed in Europe. It was designed to meet the growing needs and expectations of Professional Mobile Radio (PMR) users such as Public Safety Forces, Transport or Industry.

Publicly Available Specifications
The Publicly Available Specifications (PAS) comprise 3,000 pages of technical specifications of Tetrapol open interfaces. This means that any manufacturer can use these specifications to develop equipment that is fully compatible with TETRAPOL networks. The document is managed by the TETRAPOL Forum's technical committee.
* Tetrapol is not endorsed as standard by international standard body but it offers Publicly Available Specifications (PAS). This means that document specifying Tetrapol is available for any manufacturer that wants to develop Tetrapol compliant equipment.

Spectrum Efficiency
Tetrapol utilizes Frequency Division Multiple Access (FDMA) technique to achieve spectrum efficiency. Each Tetrapol channel is divided into 12.5 KHz or 10 KHz radio channel thus Tetrapol can achieve up to 2 voice channel within a 25 KHz radio channel.
Frequency Band
At present, Tetrapol products in the market supports frequency band in 380 – 450 MHz.
Features and Capabilities
From end user point of view, Tetrapol provides the following features and services:

The comparison among all these technologies


The comparison among these analog technologies



Learn more about analog technologies of two-way radios.

(Source: about2wayradio.com)

 
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