Digital Enhanced Cordless Telecommunications (DECT) is a cordless telephony standard maintained by ETSI. It originated in Europe, where it is the common standard, replacing earlier standards, such as CT1 and CT2. Since the DECT-2020 standard it also includes IoT communication.
Beyond Europe, it has been adopted by Australia and most countries in Asia and South America. North American adoption was delayed by United States radio-frequency regulations. This forced development of a variation of DECT called DECT 6.0, using a slightly different frequency range, which makes these units incompatible with systems intended for use in other areas, even from the same manufacturer. DECT has almost completely replaced other standards in most countries where it is used, with the exception of North America.
DECT was originally intended for fast roaming between networked base stations, and the first DECT product was Net3 wireless LAN. However, its most popular application is single-cell cordless phones connected to traditional analog telephone, primarily in home and small-office systems, though gateways with multi-cell DECT and/or DECT repeaters are also available in many private branch exchange (PBX) systems for medium and large businesses, produced by Panasonic, Mitel, Gigaset, Ascom, Cisco, Grandstream, Snom, Spectralink, and RTX. DECT can also be used for purposes other than cordless phones, such as baby monitors, wireless microphones and industrial sensors. The ULE Alliance's DECT ULE and its "HAN FUN" protocolHAN FUN, "Home Area Network FUNctional protocol". are variants tailored for home security, automation, and the internet of things (IoT).
The DECT standard includes the generic access profile (GAP), a common interoperability profile for simple telephone capabilities, which most manufacturers implement. GAP-conformance enables DECT handsets and bases from different manufacturers to interoperate at the most basic level of functionality, that of making and receiving calls. Japan uses its own DECT variant, J-DECT, which is supported by the DECT forum.
The New Generation DECT (NG-DECT) standard, marketed as CAT-iq by the DECT Forum, provides a common set of advanced capabilities for handsets and base stations. CAT-iq allows interchangeability across IP-DECT base stations and handsets from different manufacturers, while maintaining backward compatibility with GAP equipment. It also requires mandatory support for wideband audio.
DECT-2020 New Radio, marketed as NR+ (New Radio plus), is a 5G data transmission protocol which meets ITU-R IMT-2020 requirements for ultra-reliable low-latency and massive machine-type communications, and can co-exist with earlier DECT devices.ETSI TR 103 810 V1.1.1 (2021-11). Final Evaluation Report on DECT-2020 NR. ETSI, 23 November 2021.
Standards history The DECT standard was developed by ETSI in several phases, the first of which took place between 1988 and 1992 when the first round of standards were published. These were the ETS 300–175 series in nine parts defining the air interface, and ETS 300-176 defining how the units should be type approved. A technical report, ETR-178, was also published to explain the standard. Subsequent standards were developed and published by ETSI to cover interoperability profiles and standards for testing.
Named Digital European Cordless Telephone at its launch by CEPT in November 1987; its name was soon changed to Digital European Cordless Telecommunications, following a suggestion by Enrico Tosato of Italy, to reflect its broader range of application including data services. In 1995, due to its more global usage, the name was changed from European to Enhanced. DECT is recognized by the ITU as fulfilling the IMT-2000 requirements and thus qualifies as a 3G system. Within the IMT-2000 group of technologies, DECT is referred to as IMT-2000 Frequency Time (IMT-FT).
DECT was developed by ETSI but has since been adopted by many countries all over the World. The original DECT frequency band (1880–1900 MHz) is used in all countries in Europe. Outside Europe, it is used in most of Asia, Australia and South America. In the United States, the Federal Communications Commission in 2005 changed channelization and licensing costs in a nearby band (1920–1930 MHz, or 1.9 GHz), known as Unlicensed Personal Communications Services (UPCS), allowing DECT devices to be sold in the U.S. with only minimal changes. These channels are reserved exclusively for voice communication applications and therefore are less likely to experience interference from other wireless devices such as baby monitors and wireless networks.
The New Generation DECT (NG-DECT) standard was first published in 2007; it was developed by ETSI with guidance from the Home Gateway Initiative through the DECT Forum to support IP-DECT functions in home gateway/IP-PBX equipment. The ETSI TS 102 527 series comes in five parts and covers wideband audio and mandatory interoperability features between handsets and base stations. They were preceded by an explanatory technical report, ETSI TR 102 570. The DECT Forum maintains the CAT-iq trademark and certification program; CAT-iq wideband voice profile 1.0 and interoperability profiles 2.0/2.1 are based on the relevant parts of ETSI TS 102 527.
The DECT Ultra Low Energy (DECT ULE) standard was announced in January 2011 and the first commercial products were launched later that year by Dialog Semiconductor. The standard was created to enable home automation, security, healthcare and energy monitoring applications that are battery powered. Like DECT, DECT ULE standard uses the 1.9 GHz band, and so suffers less interference than Zigbee, Bluetooth, or Wi-Fi from microwave ovens, which all operate in the unlicensed 2.4 GHz ISM band. DECT ULE uses a simple star network topology, so many devices in the home are connected to a single control unit.
A new low-complexity audio codec, LC3plus, has been added as an option to the 2019 revision of the DECT standard. This codec is designed for high-quality voice and music applications such as wireless speakers, headphones, headsets, and microphones. LC3plus supports scalable 16-bit narrowband, wideband, super wideband, fullband, and 24-bit high-resolution fullband and ultra-band coding, with sample rates of 8, 16, 24, 32, 48 and 96 kHz and audio bandwidth of up to 48 kHz.
DECT-2020 New Radio protocol was published in July 2020; it defines a new physical interface based on cyclic prefix orthogonal frequency-division multiplexing (CP-OFDM) capable of up to 1.2Gbit/s transfer rate with QAM-1024 modulation. The updated standard supports multi-antenna MIMO and beamforming, FEC channel coding, and hybrid automatic repeat request. There are 17 radio channel frequencies in the range from 450MHz up to 5,875MHz, and channel bandwidths of 1,728, 3,456, or 6,912kHz. Direct communication between end devices is possible with a mesh network topology. In October 2021, DECT-2020 NR was approved for the IMT-2020 standard,World’s first non-cellular 5G technology, ETSI DECT-2020, gets ITU-R approval, setting example of new era connectivity. ETSI, 19 October 2021 for use in Massive Machine Type Communications (MMTC) industry automation, Ultra-Reliable Low-Latency Communications (URLLC), and professional wireless audio applications with point-to-point or multicast communications; the proposal was fast-tracked by ITU-R following real-world evaluations.<ref name=etsi-tr-103810/>ITU-R R15-IMT.2020-C-0053. Detailed schedule and actions for 'Way Forward' Option 2 related to "ETSI (TC DECT) and DECT Forum Proponent" and "Nufront Proponent" candidate technology submissions for IMT-2020 The new protocol will be marketed as NR+ (New Radio plus) by the DECT Forum. OFDMA and SC-FDMA modulations were also considered by the ESTI DECT committee.
OpenD is an open-source framework designed to provide a complete software implementation of DECT ULE protocols on reference hardware from Dialog Semiconductor and DSP Group; the project is maintained by the DECT forum.
Application The DECT standard originally envisaged three major areas of application: Domestic cordless telephony, using a single base station to connect one or more handsets to the public telecommunications network. Enterprise premises cordless PABXs and wireless LANs, using many base stations for coverage. Calls continue as users move between different coverage cells, through a mechanism called handover. Calls can be both within the system and to the public telecommunications network. Public access, using large numbers of base stations to provide high capacity building or urban area coverage as part of a public telecommunications network. Wireless microphone systems, for speech-optimized applications with automatic frequency and interference management.
Of these, the domestic application (cordless home telephones) has been extremely successful. The enterprise PABX market, albeit much smaller than the cordless home market, has been very successful as well, and all the major PABX vendors have advanced DECT access options available. The public access application did not succeed, since public cellular networks rapidly out-competed DECT by coupling their ubiquitous coverage with large increases in capacity and continuously falling costs. There has been only one major installation of DECT for public access: in early 1998 Telecom Italia launched a wide-area DECT network known as "Fido" after much regulatory delay, covering major cities in Italy.DECT for Cordless Terminal Mobility. DECT Forum Newsletter. 6 March 1998 The service was promoted for only a few months and, having peaked at 142,000 subscribers, was shut down in 2001.
DECT has been used for wireless local loop as a substitute for copper pairs in the "last mile" in countries such as India and South Africa. By using directional antennas and sacrificing some traffic capacity, cell coverage could extend to over . One example is the corDECT standard.
The first data application for DECT was Net3 wireless LAN system by Olivetti, launched in 1993 and discontinued in 1995. A precursor to Wi-Fi, Net3 was a micro-cellular data-only network with fast roaming between base stations and 520 kbit/s transmission rates.
Data applications such as electronic cash terminals, traffic lights, and remote door openers also exist, but have been eclipsed by Wi-Fi, 3G and 4G which compete with DECT for both voice and data.
Characteristics The DECT standard specifies a means for a portable phone or "Portable Part" to access a fixed telephone network via radio. Base station or "Fixed Part" is used to terminate the radio link and provide access to a fixed line. A gateway is then used to connect calls to the fixed network, such as public switched telephone network (telephone jack), office PBX, ISDN, or VoIP over Ethernet connection.
Typical abilities of a domestic DECT Generic Access Profile (GAP) system include multiple handsets to one base station and one phone line socket. This allows several cordless telephones to be placed around the house, all operating from the same telephone line. Additional handsets have a battery charger station that does not plug into the telephone system. Handsets can in many cases be used as intercoms, communicating between each other, and sometimes as walkie-talkies, intercommunicating without telephone line connection.
DECT operates in the 1880–1900 MHz band and defines ten frequency channels from 1881.792 MHz to 1897.344 MHz with a band gap of 1728 kHz.