DECT™

Introduction

Digital Enhanced Cordless Telecommunications (DECT™) is the ETSI standard for short-range cordless communications, which can be adapted for many applications and can be used over unlicensed frequency allocations world-wide.

DECT™ is suited to voice (including PSTN and VoIP telephony), data and networking applications with a range up to 500 metres.

DECT™ dominates the cordless residential market and the enterprise PABX (Private Automatic Branch eXchange) market. DECT™ is also used in the Wireless Local Loop to replace copper in the 'last mile' for user premises.

The ETSI Technical Committee DECT (TC DECT) has the overall responsibility over the technology.

History and success

DECT is the second most successfully ETSI standard after GSM. The accumulated number of DECT devices manufactured from the beginning reaches 800 million of devices with a growing ratio or 100 million of devices per year. DECT dominates the wireless voice applications with a market share of 73% for all cordless technologies (including analog and proprietary). No other cordless technology can compete with DECT in world-wide acceptance, interoperability, and capability of the standard for telephony (PSTN and VoIP) applications.

Currently DECT is gaining market share due to the replacement of old analog technologies and the reduction of market share of digital technologies based on voice over IEEE 802.11. The reduced cost of DECT chipsets due to the mass production allows also DECT to enter in the market of replacement of wired fixed phones.

The capability of the standard for telephony applications is unrivalled by any other technology. In addition to a complete repertory of signalling and procedures for PSTN and ISDN scenarios, TC DECT has developed during the last years (as part as New Generation DECT) a complete set of signalling procedures for VoIP telephony. The standard now includes wideband and super-wideband codecs and detailed audio specifications (defining parameters such as audio levels, equalization masks and echo cancelation). This makes possible the achievement of real interoperability from an end user perspective.

A World-wide standard

DECT was initially developed as a European standard. It was later adopted by many other countries and today has become a word-wide de-facto standard for cordless telephony applications.

Currently, DECT is available almost worldwide (the technology has been adopted in over 110 countries). The United States market was, in practice, opened to DECT by an FCC decision in 2005, and is now one of the most important markets in terms of growing. Even South Korea (a traditional Japan influence area) is open to DECT. Currently Japan has its own technology for the application (PHS), but there are negotiations ongoing to allow also the introduction of DECT in Japan.

The most common spectrum allocation is 1 880 MHz to 1 900 MHz used in Europe. This spectrum is unlicensed and technology exclusive, what ensures an interference free operation, and contributes to the very high spectral efficiency of the technology. The bands 1900 MHz to 1 920 MHz and 1 910 MHz to 1 930 MHz are also very common in many countries outside Europe. In the US the frequency allocation is 1920-1930, known as UPCS band. In this case, the allocation is not technology exclusive, but is, in practice, enough "clean", to achieve similar interference-free operation.

Frequency allocations in Europe of 1900-1920 (shared with UTRAN TDD), 1920-1980 (shared with the uplink of UTRAN FDD) and 2010-2025 have been foreseen by IMT-2000 for potential expansion of the standard (see EN 301 908-10 ), but actually they are not used yet.

Technology overview

General

• Multi carrier TDMA technology with TDD (time division duplex)
• Frame time 10 ms,
• Number of slots per frame: 24 (2 x 12)
• Modulation: GFSK, 4PSK, 8PSK, 16QAM and 64QAM
• Average transmission power: 10 mW (250 mW peak) in Europe, 4 mW (100 mW peak) in the US
• Seamless handover and full mobility management capabilities with authentication and ciphering

Audio and telephony

• Supported audio codecs: G.726, G.711, G.722 (wideband), G.729.1 (wideband) and MPEG-4 ER LD AAC (wideband and super-wideband)
• Detailed audio specifications for narrowband (3,1 kHz) telephony and wideband (7 kHz) telephony
• Complete set of signalling and NWK procedures for PSTN/ISDN telephony, VoIP telephony (SIP or H.323), mixed scenarios (FP with PSTN and VoIP network connectivity), PABX environments, WLL (Wireless Local Loop) applications and CTM (Cordless Terminal Mobility) applications.

Data

• DECT Packet Radio Service (DPRS) providing packet data up to 840 kbit/s (GFSK modulation) or up to 5 Mbit/s (High Level Modulation) with support for multibearer, asymmetric connections, and efficient packet data handling.
• Channel access time (from suspend state) = 15 ms (first bearer), 25 ms (additional bearers)
• Connection Oriented and Full Mobility Management Procedures (similar to a cellular system)
• Simplified modes for Wireless LAN operation, and low data rate applications.
• Dual ARQ architecture with ARQ at MAC and at DLC layer.
• Optional channel encoding (based on Turbo coding) for use with High Level Modulation modes.
• Additional Data profiles for circuit mode transmission and for ISDN emulation

Channel Selection Procedures:

• Automatic frequency planning based on a distributed algorithm (Dynamic Channel Allocation, DCA) executed by the Portable Parts
• No need for any frequency planning at all: all DECT devices may access to the whole DECT spectrum.
• DECT DCA can be considered a preliminary implementation of what today is called "Cognitive radio". It implements the paradigm "Spectrum Sensing Cognitive radio".

Miscellaneous:

• Low power consumption due to technology architecture.
• Low cost of DECT chipsets and radio parts due to mass production.

Testing and certification:

• Complete set of DECT Testing specifications covering radio aspects, audio and speech aspects and the different layers of the protocol.
• Harmonized Standards for radio conformance in Europe according to EC R&TTE directive.
• Industry certification program covering radio, audio and protocol aspects.

Our Role & Activities

The ETSI Technical Committee DECT (TC DECT) has the overall responsibility over the DECT standard and technology.

The DECT committee meets every two-three months for its plenary (face-to-face) meetings. In addition to that, the TC has working groups or plenary e-meetings via tele-conferencing at least every month.

TC DECT has well established procedures for maintenance and evolution of the technology. A Change control mechanism allows the handling of maintenance requests received from any ETSI member on a regular basis. A Work Item creation system allows members to propose new evolution paths or the creation of new specifications. Approximately 200 Change requests and 500 Input papers are handled every year. The response to any maintenance request is usually less than two-three months.

TC DECT has a long term vision of the standard and considers that it fulfils a basic need of the information society.

Current TC DECT developing areas:

DECT. 6.0

DECT 6.0 is the name (created by DECT Forum) given to the version of the standard intended for operation in the United States market. DECT 6.0 is basically identical to DECT with a minor adaptation in the Physical Layer (different frequency and power levels) as required by the FCC. The development of DECT 6.0 is now completed.

The New Generation DECT™

New Generation DECT™ (NG-DECT) is the name given to the further development of the DECT standard performed since 2006 with primary target on VoIP applications. NG-DECT is implemented by the addition of new functions to the DECT base standard (keeping back-compatibility with all previous developments) and the creation of a dedicated set of Application Profiles defining new types of products.

DECT Forum has coined the term "CAT-iq™," as a commercial brand for NG-DECT products. From technical perspective both terms have identical meaning. CAT-iq™ also includes a certification program to ensure technology compliance with the NG-DECT standards, enforcing the compliance with the detailed testing standards developed by TC DECT.

New Generation DECT includes the following new features:

• Superior voice quality better than any existing technology (Wideband and super-wideband Speech)
• New codecs G.722, G.729.1 and MPEG-4.
• Improved audio models (including acoustic interface) jointly developed with the participation of audio experts.
• Complete set of signalling and procedures for VoIP (SIP and H.323) and mixed (base stations with dual PSTN and VoIP connectivity) scenarios supporting features such as multiple lines, multiple calls, call line and name identification, call transfer, conferencing, intrusion call, etc...
• New DECT headset devices (with DECT radio i/f).
• Support of Broadband Data and Audio Streaming
• Video telephony capability
• Streaming CD Quality Audio Content
• Home Monitoring, Door phone, Baby monitor, Mailbox
• Plug & Play functionality of all components
• Enhanced security
• Automatic device detection and configuration (easy pairing).
• Complete testing specifications.

New Generation DECT™ specifications started to appear in March 2007, with the publication of an Overview Report (TR 102 570). Other New Generation DECT™ documents focus on Wideband speech (TS 102 527-1 ), on IP Packet data (TS 102 527-2 ), on Extended Wideband speech services (TS 102 527-3 ) and on Light Data Services (TS 102 527-4 ). The next planned specification is the TS 102 527-5 (additional set of features for VoIP services) scheduled for January of 2011.

DECT Enhanced security

The current DECT authentication and ciphering algorithms, designed around 1990, and being state of the art at that time, have resisted 18 years without any known attack in practical terms. Due to the accumulated increase in computer power, TC DECT considers it is the time to face a general revision of the algorithms and key lengths in order to guarantee a high standard of protection. This task will be performed during the year 2010 and new strengthened algorithms will be included in the version of the DECT base standard scheduled for January 2011.

DECT Ultra Low Power

DECT Ultra Low Power (DULP) is a proposed new technology based on DECT, and intended for Machine to Machine communications such as Home and Industrial automation. The main characteristics of the technology are ultra low power consumption (much lower than IEEE 802.11) and wider coverage (much wider than IEEE 802.15). DECT ULP will be a technical topic in the TC DECT work programme during 2010.

Wireless Factory

TC DECT participates actively in the ETSI initiative Wireless Factory and is one of the selected candidatetechnologies for Industrial Automation and Industrial communication needs. Further work on the topic is expected during year 2010.

DECT Advanced

DECT Advanced is the name of the Long Term Evolution of the DECT standard. It is defined as a broadband 4G technology with a coverage range intermediate between IEEE 802.11 and 3GPP LTE. The basic technology proposal combines OFDMA with MIMO, subcarrier spacing intermediate between IEEE 802.11 and LTE, modulation up to 256 QAM, Time Division Duplex, optimized for high MIMO efficiency in pico-cellular environments, and channel selection procedures based on Cognitive Radio paradigms. The target data rate of DECT Advanced is 1 Gigabit/sec.

Compared with existing 4G technology proposals, DECT Advanced will have a wider coverage and wall-penetrating properties than IEEE 802.11 and its evolutions, as well as a more refined MAC design based on scheduling algorithm. Compared to the 4G proposals for cellular telephony (LTE and IEEE 802.16), DECT Advanced will have shorter coverage but it will provide 4 times more bit rate for a given FFT complexity. It will also include a completely different frequency selection strategy intended for uncoordinated use over unlicensed channels.

DECT Advanced is intended for both professional and public environment, such as building coverage, factories, ports, airports, railways and Wireless Local Loop (WLL). Future applications requiring high data rate and real time communications will definitely benefit from this very promising technology.
DECT Advanced is a technical topic in the TC DECT work programme.

Other Services

DECT™ registration for the industry

DECT™ Codes are assigned by ETSI for manufacturers, Installers and Operators providing for portable parts and fixed parts for DECT™.
ETSI keeps the following registrations on behalf of the DECT™ Industry.

• Equipment Manufacturer's Code (EMC)
• Equipment Installer's Code (EIC)
• Public Operator Code (POC)
• Public Operator Code TRIAL (POC TRIAL).

DECT™ is a registered trademark of ETSI in Europe for the benefit of ETSI members.

Standards

The ETSI DECT standard consists of approximately 250 deliverables, including test specifications. The following list provides hyperlinks for downloading the most common DECT deliverables. Please use the ETSI Work Programme to find further related standards.