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 820 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 of 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. Finally, the recent DECT ULE (Ultra Low Energy) is still more promising as it opens the technology to the M2M market.
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 is open to DECT and recently also Japan has opened the market to the technology, market traditionally dominated by The Personal Handy-phone System (PHS).
The most common spectrum allocation is 1,880 MHz to 1,900 MHz used in Europe. This spectrum is unlicensed and technology exclusive, which ensures an interference free operation, and contributes to the very high spectral efficiency of the technology. The bands 1,900 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 1,900-1,920 (shared with UTRAN TDD), 1,920-1,980 (shared with the uplink of UTRAN FDD) and 2,010-2,025 have been foreseen by IMT-2000 for potential expansion of the standard, but actually they are not used yet.
- 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
- 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".
- 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
The TC DECT standard is continually updated in order to take into account the developments in the technology, mainly DECT™ New Generation and DECT™ Ultra Low Energy (ULE). Regional variants are also being investigated.
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 a 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
- Software update over the air (SUOTA) for handsets and other cordless devices
- List access services (LAS) for convenient exchange of call lists, like incoming call list
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), IP Packet data (TS 102 527-2), Extended Wideband speech services (TS 102 527-3) Light Data Services (TS 102 527-4) and additional set of features for extended wideband speech (TS 102 527-5). Other specifications will be developed in the future.
DECT Ultra Low Energy (ULE)
DECT Ultra Low Energy (ULE) is a 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 and Bluetooth Low Energy).
The technology is suitable for sensors, alarms, Machine-to-Machine (M2M) applications and industrial automation. The ULE technology may also be applied to utility meters and related devices and therefore has implications for the operation of smart grids. Examples of applications include the following:
- Actuator devices
Devices with fast response times (Fixed Part to Portable Part and vice versa) commonly used, for instance, in eelectricity plugs or motor drivers such as a sunscreen
- Slow Actuator devices
Devices with relatively fast response times (Fixed Part to Portable Part and vice versa) commonly used, for instance, in thermostats
- Sensor devices
Devices with long sleep times and fast response times from Portable Part to Fixed Part. Typical examples are smoke detectors and motion detectors
The ULE Alliance has also established certification programs for Home Automation Networks based on ULE technology.
The maximum radio coverage range of DECT ULE will be as wide as standard DECT technology. Smaller coverage may be defined for specific applications due to power consumption and spectrum use considerations.
DECT ULE is based on the DECT base standard (EN 300 175, parts 1 to 8) and it has been designed to be coexistent with other DECT applications (including GAP or NG-DECT). Different types of DECT devices may be used over the same spectrum, and mixed devices supporting DECT ULE and other DECT applications may be built. It is foreseen that the majority of DECT ULE RFPs and some DECT ULE PPs will be mixed devices.
DECT 6.0™ and J-DECT
Currently, two regional variants of the DECT technology are developed to serve the special radio regulation requirements of US and Japan:
DECT in US is working in the 1,920 – 1,930 MHz band and is branded as DECT 6.0. 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 completed.
DECT in Japan is working in the 1,894 – 1,904 MHz band and is branded as J-DECT. This frequency allocation is located within the existing Enterprise PHS Systems band and therefore it needs the speciality for the coexistence with PHS Systems to avoid harmful radio interference issues. With regard to the usable part of Spectrum the “MIC” (Ministry of Internal Affairs and Communications, the Regulatory agency in Japan) has defined the operating frequency band for J-DECT: emissions of a frequency of 1,895.616 MHz or an integral multiple of 1,728 KHz added to 1,895.616 MHz in a range from 1,895.616 MHz to 1,902.528 shall be used.
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.
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.
TS 103 159-1
Digital Enhanced Cordless Telecommunications (DECT); Ultra Low Energy (ULE); Machine to Machine Communications; Part 1: Test Framework and Profile Test Specification (PTS) for Home Automation Network (phase 1)
TS 102 527-1
Digital Enhanced Cordless Telecommunications (DECT); New Generation DECT; Part 1: Wideband speech
TS 102 527-3
Digital Enhanced Cordless Telecommunications (DECT); New Generation DECT; Part 3: Extended wideband speech services
TS 102 527-5
Digital Enhanced Cordless Telecommunications (DECT); New Generation DECT; Part 5: Additional feature set nr. 1 for extended wideband speech services
TS 102 841
Digital Enhanced Cordless Telecommunications (DECT); New Generation DECT; Extended wideband speech services; Profile Test Specification (PTS) and Test Case Library (TCL)
TS 102 843
Digital Enhanced Cordless Telecommunications (DECT); New Generation DECT; Additional feature set nr.1 for extended wideband speech services; Profile Test Specification (PTS) and Test Case Library (TCL)
EN 300 175-1
Digital Enhanced Cordless Telecommunications (DECT); Common Interface (CI); Part 1: Overview
EN 300 175-2
Digital Enhanced Cordless Telecommunications (DECT); Common Interface (CI); Part 2: Physical Layer (PHL)
EN 300 175-3
Digital Enhanced Cordless Telecommunications (DECT); Common Interface (CI); Part 3: Medium Access Control (MAC) layer
EN 300 175-4
Digital Enhanced Cordless Telecommunications (DECT); Common Interface (CI); Part 4: Data Link Control (DLC) layer
EN 300 175-5
Digital Enhanced Cordless Telecommunications (DECT); Common Interface (CI); Part 5: Network (NWK) layer
EN 300 175-6
Digital Enhanced Cordless Telecommunications (DECT); Common Interface (CI); Part 6: Identities and addressing
EN 300 175-7
Digital Enhanced Cordless Telecommunications (DECT); Common Interface (CI); Part 7: Security features
EN 300 175-8
Digital Enhanced Cordless Telecommunications (DECT); Common Interface (CI); Part 8: Speech and audio coding and transmission
EN 300 444
Digital Enhanced Cordless Telecommunications (DECT); Generic Access Profile (GAP)
TS 102 939-1
Digital Enhanced Cordless Telecommunications (DECT); Ultra Low Energy (ULE); Machine to Machine Communications; Part 1: Home Automation Network (phase 1)
TR 103 089
Digital Enhanced Cordless Telecommunications (DECT); DECT properties and radio parameters relevant for studies on compatibility with cellular technologies operating on frequency blocks adjacent to the DECT frequency band
EN 300 176-2
Digital Enhanced Cordless Telecommunications (DECT); Test specification; Part 2: Audio and speech
EN 301 649
Digital Enhanced Cordless Telecommunications (DECT); DECT Packet Radio Service (DPRS)
TS 102 527-4
Digital Enhanced Cordless Telecommunications (DECT); New Generation DECT; Part 4: Light Data Services; Software Update Over The Air (SUOTA), content downloading and HTTP based applications