Digital Enhanced Cordless Telecommunications
Encyclopedia
Digital Enhanced Cordless Telecommunications (Digital European Cordless Telecommunications), usually known by the acronym DECT, is a digital communication standard, which is primarily used for creating cordless phone systems. It originated in Europe, where it is the universal standard, replacing earlier cordless phone standards, such as 900 MHz CT1
CT1
CT1 stands for Cordless telephone generation 1 and is an analog cordless telephone standard that was standardized by the European Conference of Postal and Telecommunications Administrations in 1984 and deployed in eleven European countries...

 and CT2
CT2
CT2 is a cordless telephony standard that was used in the early 1990s to provide short-range proto-mobile phone service in some countries in Europe. It is considered the precursor to the popular DECT system...

.

Beyond Europe, it has been adopted by Australia
Australia
Australia , officially the Commonwealth of Australia, is a country in the Southern Hemisphere comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands in the Indian and Pacific Oceans. It is the world's sixth-largest country by total area...

, and most countries in Asia
Asia
Asia is the world's largest and most populous continent, located primarily in the eastern and northern hemispheres. It covers 8.7% of the Earth's total surface area and with approximately 3.879 billion people, it hosts 60% of the world's current human population...

 and South America
South America
South America is a continent situated in the Western Hemisphere, mostly in the Southern Hemisphere, with a relatively small portion in the Northern Hemisphere. The continent is also considered a subcontinent of the Americas. It is bordered on the west by the Pacific Ocean and on the north and east...

. North American adoption was delayed by United States
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...

 radio frequency regulations. This forced development of a variation of DECT, called DECT 6.0, using a slightly different frequency range; the technology is nearly identical, but the frequency difference makes the technology incompatible with systems in other areas, even from the same manufacturer. DECT has almost universally replaced other standards in most countries where it is used, with the exception of North America.

DECT is used primarily in home and small office systems, but is also available in many PBX systems for medium and large businesses. DECT can also be used for purposes other than cordless phones. Voice applications, such as baby monitor
Baby monitor
A baby monitor, also known as a baby alarm, is a radio system used to remotely listen to sounds made by an infant. The transmitter unit, equipped with a microphone, is placed near to the child. It transmits the sounds the baby makes by radio waves to a receiver unit with a speaker carried by, or...

s, are becoming common. Data applications also exist, but have been eclipsed by Wi-Fi
Wi-Fi
Wi-Fi or Wifi, is a mechanism for wirelessly connecting electronic devices. A device enabled with Wi-Fi, such as a personal computer, video game console, smartphone, or digital audio player, can connect to the Internet via a wireless network access point. An access point has a range of about 20...

. 3G cellular also competes with both DECT and Wi-Fi for both voice and data. Nowadays you can find DECT as well in special applications like Remote Controls for industrial applications.

In January 2011 a low power variant (DECT ULE - ultra low energy) was discussed at the DECT World and CAT-iq Conference with a whitepaper presented by Sitel (Now Dialog) Semiconductor. The first successful interoperability tests were announced by the DECT Forum in June 2011. And in September 2011 Dialog Semiconductor announced the first commercially availalable DECT ULE devices. Unlike standard DECT, the low power variant enables this standard to be used in battery powered devices such as smartphone app controllable home automation or security systems.

DECT handsets and bases from different manufacturers typically work together at the most basic level of functionality: making and receiving calls. The DECT standard includes a standardized interoperability profile for simple telephone capabilities, called GAP
Generic access profile
The Generic Access Profile describes a set of mandatory requirements to allow any conforming DECT Fixed Part to interoperate with any conforming DECT Portable Part in order to provide basic telephony services when attached to a 3.1 kHz telephone network .The objective of GAP is to ensure...

, which most manufacturers implement. The standard also contains several other interoperability profiles, for data and for radio local-loop services.

Application

The DECT standard fully specifies a means for a portable unit, such as a cordless telephone, to access a fixed telecoms network via radio. But, unlike the GSM standards, does not specify any internal aspects of the fixed network itself. Connectivity to the fixed network (which may be of many different kinds) is done through a base station
Base station
The term base station can be used in the context of land surveying and wireless communications.- Land surveying :In the context of external land surveying, a base station is a GPS receiver at an accurately-known fixed location which is used to derive correction information for nearby portable GPS...

 or "Radio Fixed Part" to terminate the radio link, and a gateway
Gateway (telecommunications)
In telecommunications, the term gateway has the following meaning:*In a communications network, a network node equipped for interfacing with another network that uses different protocols....

 to connect calls to the fixed network. In most cases the gateway connection is to the public switched telephone network
Public switched telephone network
The public switched telephone network is the network of the world's public circuit-switched telephone networks. It consists of telephone lines, fiber optic cables, microwave transmission links, cellular networks, communications satellites, and undersea telephone cables, all inter-connected by...

 or telephone jack, although connectivity with newer technologies such as Voice over IP
Voice over IP
Voice over Internet Protocol is a family of technologies, methodologies, communication protocols, and transmission techniques for the delivery of voice communications and multimedia sessions over Internet Protocol networks, such as the Internet...

 has become available. There are also other devices such as some baby monitor
Baby monitor
A baby monitor, also known as a baby alarm, is a radio system used to remotely listen to sounds made by an infant. The transmitter unit, equipped with a microphone, is placed near to the child. It transmits the sounds the baby makes by radio waves to a receiver unit with a speaker carried by, or...

s utilizing DECT, and in these devices there is no gateway functionality.

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 telecoms 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 telecoms network.
  • Public access, using large numbers of base stations to provide high capacity building or urban area coverage as part of a public telecoms network.


Of these, the domestic application (cordless home telephones) has been extremely successful. The enterprise PABX market had some success, and all the major PABX vendors have offered DECT access options. 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
Telecom Italia
Telecom Italia is the largest Italian telecommunications company, also active in the media and manufacturing industries. Now a private concern listed on the Borsa Italiana, it was founded in 1994 by the merger of several state-owned telecommunications companies, the most important of which was...

 launched a DECT network known as "Fido" after much regulatory delay, covering major cities in Italy. The service was promoted for only a few months and, having peaked at 142,000 subscribers, was shut down in 2001.

DECT has also been used for Fixed Wireless Access 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 10 km. In Europe the power limit laid down for use of the DECT spectrum (250 mW peak) was expressed in ERP
Effective radiated power
In radio telecommunications, effective radiated power or equivalent radiated power is a standardized theoretical measurement of radio frequency energy using the SI unit watts, and is determined by subtracting system losses and adding system gains...

, rather than the more commonly-used EIRP, permitting the use of high-gain directional antennas to produce much higher EIRP and hence long ranges.

The standard is also used in electronic cash terminals, traffic lights, and remote door openers.

DECT 6.0

The "6.0" in DECT 6.0 does not specify a spectrum band, but is a marketing term coined by Siemens
Siemens
Siemens may refer toSiemens, a German family name carried by generations of telecommunications industrialists, including:* Werner von Siemens , inventor, founder of Siemens AG...

, for DECT devices manufactured for use in the U.S. and Canada. Although DECT 6.0 operates at 1.9 GHz, Siemens decided the term DECT 1.9 might have confused customers who equate larger numbers (such as the 2.4 and 5.8 in existing 2.4 GHz and 5.8 GHz cordless telephones) with later products. The DECT and DECT 6.0 technologies are essentially identical, except for operating frequency.

The term DECT 6.0 is also used in Australia .

VoIP/IP-DECT

In business, DECT has become an essential part of many PABX installations with manufacturer's proprietary methods of supporting PABX features over the DECT standard. Since the onset of the migration from TDM PBXs to VoIP and VoIP hybrid solutions, manufacturers such as Lantiq
Lantiq
Lantiq is an international fabless semiconductor business of approximately 1,000 people. It was formed in 2009 when Infineon Technologies sold its Wireline Communications Division....

, Ascom Wireless Solutions, Aastra Technologies
Aastra Technologies
Aastra Technologies Limited headquartered in Concord, Ontario, Canada, makes products and systems for accessing communication networks including the Internet...

, Philips
Philips
Koninklijke Philips Electronics N.V. , more commonly known as Philips, is a multinational Dutch electronics company....

, and Polycom
Polycom
Polycom is a multinational corporation with approximately 3,200 employees worldwide and an annual revenue of approximately $1.2 billion in 2010. The company manufactures and sells telepresence and voice communications solutions.-Company History 1990:...

 have developed IP-DECT solutions where the backhaul from the base station is VoIP (H.323
H.323
H.323 is a recommendation from the ITU Telecommunication Standardization Sector that defines the protocols to provide audio-visual communication sessions on any packet network...

 or SIP
Session Initiation Protocol
The Session Initiation Protocol is an IETF-defined signaling protocol widely used for controlling communication sessions such as voice and video calls over Internet Protocol . The protocol can be used for creating, modifying and terminating two-party or multiparty sessions...

) while the handset loop is still DECT. These solutions are sometimes restricted by the cost of the base station but may be economical where the concentration of users is high. PBX networking vendors such as Cisco promote the adoption of handsets that use VoIP over local Wifi
WIFI
WIFI is a radio station broadcasting a brokered format. Licensed to Florence, New Jersey, USA, the station is currently operated by Florence Broadcasting Partners, LLC.This station was previously owned by Real Life Broadcasting...

 as the replacement for DECT, but this imposes significant overhead on the design and complexity of the WiFi network in order to provide roaming, coverage and reservation of bandwidth, not to mention quality of service. However, this avoids the need for a separate DECT radio network. Other potential competitors for office installations include the Personal Handy-phone System
Personal Handy-phone System
The Personal Handy-phone System , also marketed as the Personal Access System and commercially branded as Xiaolingtong in China, is a mobile network system operating in the 1880–1930 MHz frequency band, used mainly in Japan, China, Taiwan, and some other Asian countries and...

 (popular in Asia), and the use of private calls in a local microcell
Microcell
A microcell is a cell in a mobile phone network served by a low power cellular base station , covering a limited area such as a mall, a hotel, or a transportation hub. A microcell is usually larger than a picocell, though the distinction is not always clear...

 (using a cellular phone technology).

DECT ULE

The latest DECT variant is DECT ULE, or DECT Ultra low energy. The standard was first discussed in January 2011 and the first commercial products were launched later that year by Dialog Semiconductor. Like DECT, DECT ULE standard uses the 1.9GHz band so suffers less interference than Zigbee
ZigBee
ZigBee is a specification for a suite of high level communication protocols using small, low-power digital radios based on an IEEE 802 standard for personal area networks. Applications include wireless light switches, electrical meters with in-home-displays, and other consumer and industrial...

, Bluetooth
Bluetooth
Bluetooth is a proprietary open wireless technology standard for exchanging data over short distances from fixed and mobile devices, creating personal area networks with high levels of security...

 or WiFi
WIFI
WIFI is a radio station broadcasting a brokered format. Licensed to Florence, New Jersey, USA, the station is currently operated by Florence Broadcasting Partners, LLC.This station was previously owned by Real Life Broadcasting...

, which all run on 2.4GHz.

The standard has been created to enable home automation, security, healthcare and energy monitoring applications that are battery powered and can easily connect to the web using the large number of existing DECT enabled modems and be managed using a smartphone app.

Technical development and adoption

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 9 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.

Initially named "Digital European Cordless Telephone" at its launch by CEPT in November 1987, following a suggestion by Enrico Tosato of Italy, its name was soon changed to "Digital European Cordless Telecommunications" 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." It is an ETSI standard for digital portable phones (cordless home telephones), commonly used for domestic or corporate purposes. It is recognised by the ITU
Itu
Itu is an old and historic municipality in the state of São Paulo in Brazil. The population in 2009 was 157,384 and the area is 641.68 km². The elevation is 583 m. This place name comes from the Tupi language, meaning big waterfall. Itu is linked with the highway numbered the SP-75 and are flowed...

 as fulfilling the IMT-2000 requirements and thus qualifies as a 3G
3G
3G or 3rd generation mobile telecommunications is a generation of standards for mobile phones and mobile telecommunication services fulfilling the International Mobile Telecommunications-2000 specifications by the International Telecommunication Union...

 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 MHz–1900 MHz) is used in all countries in Europe
Europe
Europe is, by convention, one of the world's seven continents. Comprising the westernmost peninsula of Eurasia, Europe is generally 'divided' from Asia to its east by the watershed divides of the Ural and Caucasus Mountains, the Ural River, the Caspian and Black Seas, and the waterways connecting...

. Outside Europe, it is used in most of Asia
Asia
Asia is the world's largest and most populous continent, located primarily in the eastern and northern hemispheres. It covers 8.7% of the Earth's total surface area and with approximately 3.879 billion people, it hosts 60% of the world's current human population...

, Australia
Australia
Australia , officially the Commonwealth of Australia, is a country in the Southern Hemisphere comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands in the Indian and Pacific Oceans. It is the world's sixth-largest country by total area...

 and South America
South America
South America is a continent situated in the Western Hemisphere, mostly in the Southern Hemisphere, with a relatively small portion in the Northern Hemisphere. The continent is also considered a subcontinent of the Americas. It is bordered on the west by the Pacific Ocean and on the north and east...

. In the United States
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...

, the Federal Communications Commission
Federal Communications Commission
The Federal Communications Commission is an independent agency of the United States government, created, Congressional statute , and with the majority of its commissioners appointed by the current President. The FCC works towards six goals in the areas of broadband, competition, the spectrum, the...

 in 2005 changed channelization and licensing costs in a nearby band (1920 MHz–1930 MHz, or 1.9 GHz
GHZ
GHZ or GHz may refer to:# Gigahertz .# Greenberger-Horne-Zeilinger state — a quantum entanglement of three particles.# Galactic Habitable Zone — the region of a galaxy that is favorable to the formation of life....

), known as Unlicensed Personal Communications Services
Unlicensed Personal Communications Services
Unlicensed Personal Communications Services or UPCS band describes the 1920-1930 MHz frequency band allocated by the United States Federal Communications Commission for short range Personal Communications Services applications in the United States, such as the Digital Enhanced Cordless...

 (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 monitor
Baby monitor
A baby monitor, also known as a baby alarm, is a radio system used to remotely listen to sounds made by an infant. The transmitter unit, equipped with a microphone, is placed near to the child. It transmits the sounds the baby makes by radio waves to a receiver unit with a speaker carried by, or...

s and wireless network
Wireless network
Wireless network refers to any type of computer network that is not connected by cables of any kind. It is a method by which homes, telecommunications networks and enterprise installations avoid the costly process of introducing cables into a building, or as a connection between various equipment...

s.

Features

Typical abilities of a domestic DECT Generic Access Profile
Generic access profile
The Generic Access Profile describes a set of mandatory requirements to allow any conforming DECT Fixed Part to interoperate with any conforming DECT Portable Part in order to provide basic telephony services when attached to a 3.1 kHz telephone network .The objective of GAP is to ensure...

 (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 jack. Additional handsets have a battery charger station which does not plug into the telephone system. Handsets can in many cases be used as intercom
    Intercom
    An intercom , talkback or doorphone is a stand-alone voice communications system for use within a building or small collection of buildings, functioning independently of the public telephone network. Intercoms are generally mounted permanently in buildings and vehicles...

    s, communicating between each other, and sometimes as walkie-talkie
    Walkie-talkie
    A walkie-talkie is a hand-held, portable, two-way radio transceiver. Its development during the Second World War has been variously credited to Donald L. Hings, radio engineer Alfred J. Gross, and engineering teams at Motorola...

    s, intercommunicating without telephone line connection.
  • Interference-free wireless operation to around 100 metres (109 yards) outdoors, much less indoors when separated by walls. Operates clearly in common congested domestic radio traffic situations, for instance, generally immune to interference from other DECT systems, Wi-Fi
    Wi-Fi
    Wi-Fi or Wifi, is a mechanism for wirelessly connecting electronic devices. A device enabled with Wi-Fi, such as a personal computer, video game console, smartphone, or digital audio player, can connect to the Internet via a wireless network access point. An access point has a range of about 20...

     networks, video sender
    Video sender
    A video sender is a device for transmitting domestic video signals wirelessly from one room to another, as for example sending the output of a satellite TV decoder located in the lounge, to a television set in the bedroom....

    s, Bluetooth
    Bluetooth
    Bluetooth is a proprietary open wireless technology standard for exchanging data over short distances from fixed and mobile devices, creating personal area networks with high levels of security...

     technology, baby monitors and other wireless devices.
  • Talk-time of several hours and standby time of several days on one battery charge.


Some systems offer:
  • A longer range between the telephone and base station (usable further from the base)
  • Extended battery talk-time, sometimes up to 24 hours

Technical properties

Some DECT properties:
  • Audio codec: G.726
    G.726
    G.726 is an ITU-T ADPCM speech codec standard covering the transmission of voice at rates of 16, 24, 32, and 40 kbit/s. It was introduced to supersede both G.721, which covered ADPCM at 32 kbit/s, and G.723, which described ADPCM for 24 and 40 kbit/s. G.726 also introduced a new...

    , G.711
    G.711
    G.711 is an ITU-T standard for audio companding. It is primarily used in telephony. The standard was released for usage in 1972. Its formal name is Pulse code modulation of voice frequencies. It is required standard in many technologies, for example in H.320 and H.323 specifications. It can also...

    , G.722
    G.722
    G.722 is a ITU-T standard 7 kHz wideband speech codec operating at 48, 56 and 64 kbit/s. It was approved by ITU-T in November 1988. Technology of the codec is based on sub-band ADPCM ....

     (wideband), G.729.1
    G.729.1
    G.729.1 is an 8-32 kbit/s embedded speech and audio codec providing bitstream interoperability with G.729, G.729 Annex A and G.729 Annex B. Its official name is G.729-based embedded variable bit rate codec: An 8-32 kbit/s scalable wideband coder bitstream interoperable with G.729.This codec has...

     (wideband) and MPEG-4
    MPEG-4
    MPEG-4 is a method of defining compression of audio and visual digital data. It was introduced in late 1998 and designated a standard for a group of audio and video coding formats and related technology agreed upon by the ISO/IEC Moving Picture Experts Group under the formal standard ISO/IEC...

     ER LD AAC (wideband and super-wideband)
  • Net bit rate: 32 kbit/s
  • Frequency: 1880 MHz–1900 MHz in Europe, 1900 MHz-1920 MHz in China,1893 MHz–1906 MHz in Japan, 1910 MHz-1930 MHz in Latin America and 1920 MHz–1930 MHz in the US and Canada, US DECT and DECT 6 products may NOT be used in the UK or Ireland as they cause and suffer from interference with the UK & Ireland 3G cellular networks with unlicensed use of such products being prohibited by UK agencies. As DECT and DECT 6.0 do not operate in the 2.4 GHz ISM band
    ISM band
    The industrial, scientific and medical radio bands are radio bands reserved internationally for the use of radio frequency energy for industrial, scientific and medical purposes other than communications....

    , they are not subject to the interference arising in this band from its use by 802.11b
    IEEE 802.11b-1999
    IEEE 802.11b-1999 or 802.11b, is an amendment to the IEEE 802.11 specification that extended throughput up to 11 Mbit/s using the same 2.4 GHz band. This specification under the marketing name of Wi-Fi has been implemented all over the world...

     and 802.11g
    IEEE 802.11g-2003
    IEEE 802.11g-2003 or 802.11g is an amendment to the IEEE 802.11 specification that extended throughput to up to 54 Mbit/s using the same 2.4 GHz band as 802.11b. This specification under the marketing name of Wi-Fi has been implemented all over the world...

     WiFi, and 2.4 GHz cordless phones.
  • Carriers: 10 (1,728 MHz spacing) in Europe, 5 (1,728 MHz spacing) in the US
  • Time slots: 2 x 12 (up and down stream)
  • Channel allocation: dynamic
  • Average transmission power: 10 mW (250 mW peak) in Europe, 4 mW (100 mW peak) in the US


The DECT physical layer
Physical layer
The physical layer or layer 1 is the first and lowest layer in the seven-layer OSI model of computer networking. The implementation of this layer is often termed PHY....

 uses:
  • Frequency division multiple access (FDMA),
  • Time division multiple access
    Time division multiple access
    Time division multiple access is a channel access method for shared medium networks. It allows several users to share the same frequency channel by dividing the signal into different time slots. The users transmit in rapid succession, one after the other, each using its own time slot. This...

     (TDMA) and
  • Time division duplex (TDD)


This means that the radio spectrum
Radio spectrum
Radio spectrum refers to the part of the electromagnetic spectrum corresponding to radio frequencies – that is, frequencies lower than around 300 GHz ....

 is divided into physical channels in two dimensions: frequency and time.

The maximum allowed power for portable equipment as well as base stations is 250 mW. A portable device radiates an average of about 10 mW during a call as it is only using one of 24 time slots to transmit.

The DECT media access control
Media Access Control
The media access control data communication protocol sub-layer, also known as the medium access control, is a sublayer of the data link layer specified in the seven-layer OSI model , and in the four-layer TCP/IP model...

 layer controls the physical layer and provides connection oriented, connectionless and broadcast
Broadcasting
Broadcasting is the distribution of audio and video content to a dispersed audience via any audio visual medium. Receiving parties may include the general public or a relatively large subset of thereof...

 services to the higher layers.

The DECT data link layer
Data link layer
The data link layer is layer 2 of the seven-layer OSI model of computer networking. It corresponds to, or is part of the link layer of the TCP/IP reference model....

 uses LAPC (Link Access Protocol Control), a specially designed variant of the ISDN
Integrated Services Digital Network
Integrated Services Digital Network is a set of communications standards for simultaneous digital transmission of voice, video, data, and other network services over the traditional circuits of the public switched telephone network...

 data link protocol called LAPD. They are based on HDLC.

The DECT network layer
Network layer
The network layer is layer 3 of the seven-layer OSI model of computer networking.The network layer is responsible for packet forwarding including routing through intermediate routers, whereas the data link layer is responsible for media access control, flow control and error checking.The network...

 always contains the following protocol entities:
  • Call Control (CC)
  • Mobility Management (MM)


Optionally it may also contain others:
  • Call Independent Supplementary Services (CISS)
  • Connection Oriented Message Service (COMS)
  • Connectionless Message Service (CLMS)


All these communicate through a Link Control Entity (LCE).

The call control protocol is derived from ISDN DSS1, which is a Q.931
Q.931
ITU-T Recommendation Q.931 is ISDN's connection control protocol, roughly comparable to TCP in the Internet Protocol stack. Q.931 doesn't provide flow control or perform retransmission, since the underlying layers are assumed to be reliable and the circuit-oriented nature of ISDN allocates...

 derived protocol. Many DECT-specific changes have been made. The mobility management protocol includes many elements similar to the GSM protocol, but also includes elements unique to DECT.

Unlike the GSM protocol, the DECT network specifications do not define cross-linkages between the operation of the entities (for example, Mobility Management and Call Control). The architecture presumes that such linkages will be designed into the interworking unit that connects the DECT access network to whatever mobility-enabled fixed network is involved. By keeping the entities separate, the handset is capable of responding to any combination of entity traffic, and this creates great flexibility in fixed nework design without breaking full interoperability.

DECT GAP
Generic access profile
The Generic Access Profile describes a set of mandatory requirements to allow any conforming DECT Fixed Part to interoperate with any conforming DECT Portable Part in order to provide basic telephony services when attached to a 3.1 kHz telephone network .The objective of GAP is to ensure...

 is an interoperability profile for DECT. The intent is that two different products from different manufacturers that both conform not only to the DECT standard, but also to the GAP profile defined within the DECT standard, are able to interoperate for basic calling. The DECT standard includes full testing suites for GAP, and GAP products on the market from different manufacturers are in practice interoperable for the basic functions.

Security

The DECT media access control layer also provides encryption
Encryption
In cryptography, encryption is the process of transforming information using an algorithm to make it unreadable to anyone except those possessing special knowledge, usually referred to as a key. The result of the process is encrypted information...

 services with the DECT Standard Cipher
DECT Standard Cipher
DECT Standard Cipher is an encryption standard, used in DECT phones to protect communication between a handset and its associated base station...

 (DSC). The encryption is fairly weak
Key size
In cryptography, key size or key length is the size measured in bits of the key used in a cryptographic algorithm . An algorithm's key length is distinct from its cryptographic security, which is a logarithmic measure of the fastest known computational attack on the algorithm, also measured in bits...

, using a 35-bit initialization vector
Initialization vector
In cryptography, an initialization vector is a fixed-size input to a cryptographic primitive that is typically required to be random or pseudorandom...

 and encrypting the voice stream with 64-bit encryption.

The security algorithm has been broken. Another attack involves impersonating a DECT base station, which allows calls to be listened to, recorded, and re-routed to a different destination.

DECT for data networks

Other interoperability profiles exist in the DECT suite of standards, and in particular the DPRS (DECT Packet Radio Services) bring together a number of prior interoperability profiles for the use of DECT as a wireless LAN and wireless internet access service. With good range (up to 200 m indoors and 6 km using directional antennae outdoors), dedicated spectrum, high interference immunity, open interoperability and data speeds of around 500 kbit/s, DECT appeared at one time to be a superior alternative to Wi-Fi
Wi-Fi
Wi-Fi or Wifi, is a mechanism for wirelessly connecting electronic devices. A device enabled with Wi-Fi, such as a personal computer, video game console, smartphone, or digital audio player, can connect to the Internet via a wireless network access point. An access point has a range of about 20...

. The protocol capabilities built into the DECT networking protocol standards were particularly good at supporting fast roaming in the public space, between hotspots operated by competing but connected providers. The first DECT product to reach the market, Olivetti's Net3
Net3
Net3 was a Wifi-like system developed, manufactured and commercialised by Olivetti in the early 1990s. It could wirelessly connect PCs to an Ethernet fixed LAN at a speed of up to 512kb/s, over a very wide area...

, was a wireless LAN, and German firms Dosch & Amand and Hoeft & Wessel built niche businesses on the supply of data transmission systems based on DECT.

However, the timing of the availability of DECT, in the mid 1990s, was too early to find wide application for wireless data outside niche industrial applications. Whilst contemporary providers of Wi-Fi struggled with the same issues, providers of DECT retreated to the more immediately lucrative market for cordless telephones. A key weakness was also the inaccessibility of the U.S. market, due to FCC spectrum restrictions at that time. By the time mass applications for wireless Internet had emerged, and the U.S. had opened up to DECT, well into the new century, the industry had moved far ahead in terms of performance and DECT's time as a wireless data transport had passed.

Radio links

DECT operates in the 1880–1900 MHz band and defines ten channels from 1881.792 MHz to 1897.344 MHz with a band gap of 1728 kHz. Each base station frame provides 12 duplex speech channels, with each time slot occupying any channel. DECT operates in multicarrier/TDMA/TDD structure. DECT also provides Frequency-hopping spread spectrum
Frequency-hopping spread spectrum
Frequency-hopping spread spectrum is a method of transmitting radio signals by rapidly switching a carrier among many frequency channels, using a pseudorandom sequence known to both transmitter and receiver...

 over TDMA
Time division multiple access
Time division multiple access is a channel access method for shared medium networks. It allows several users to share the same frequency channel by dividing the signal into different time slots. The users transmit in rapid succession, one after the other, each using its own time slot. This...

/TDD structure. If frequency-hopping is avoided, each base station can provide up to 120 channels in the DECT spectrum before frequency reuse. Each time slot can be assigned to a different channel in order to exploit advantages of frequency-hopping and to avoid interference from other users in asynchronous fashion.

XDECT R

XDECT R is a Uniden
Uniden
is a Japanese company in the wireless communication industry.-History:Uniden was established on February 7, 1966 by its founder Hideo Fujimoto...

 technology for extending the range of DECT phones (apparently indefinitely) by using multiple repeater stations. The company has demonstrated the technology to a 2.2 kilometre range in Australia.
XDECTR is not a "technology" but a marketing term used by Uniden to differentate their products for the consumer.

Health and safety

DECT is a microwave technology, with science similar to mobile phones, baby monitors, Wi-Fi, and other cordless telephone technologies. As with all such technologies, consensus is that there are negligible health effects from very low levels of microwave radiation. Most studies have been unable to discount any link to health effects, or have been inconclusive. Nevertheless, there has been persistent controversy over their health safety, and some national and international agencies have made specific recommendations about exposure.

See also

  • Generic access profile
    Generic access profile
    The Generic Access Profile describes a set of mandatory requirements to allow any conforming DECT Fixed Part to interoperate with any conforming DECT Portable Part in order to provide basic telephony services when attached to a 3.1 kHz telephone network .The objective of GAP is to ensure...

     (GAP)
  • GSM Interworking Profile
    GSM Interworking Profile (DECT)
    The GSM Interworking Profile, usually abbreviated to GIP and sometimes to IWP, is a profile for DECT that allows a DECT base station to form part of a GSM network, given suitable handsets. While proposed and tested, notably in Switzerland in 1995, the system has never been commercially deployed...

     (GIP)
  • IP-DECT
    IP-DECT
    IP-DECT is a technology used for on-site wireless communications. It uses the DECT air interface for reliable wireless voice and data communication between handsets and base stations and the well established VoIP technology for the corded voice communication between base stations and server...

  • CorDECT
    CorDECT
    corDECT is a wireless local loop standard developed in India by IIT Madras and Midas Communications at Chennai, under leadership of Prof Ashok Jhunjhunwala, based on the DECT digital cordless phone standard.- Overview :...

  • Unlicensed Personal Communications Services
    Unlicensed Personal Communications Services
    Unlicensed Personal Communications Services or UPCS band describes the 1920-1930 MHz frequency band allocated by the United States Federal Communications Commission for short range Personal Communications Services applications in the United States, such as the Digital Enhanced Cordless...

  • Wireless local loop
    Wireless local loop
    Wireless local loop , is a term for the use of a wireless communications link as the "last mile / first mile" connection for delivering plain old telephone service and/or broadband Internet to telecommunications customers....

  • Microcell
    Microcell
    A microcell is a cell in a mobile phone network served by a low power cellular base station , covering a limited area such as a mall, a hotel, or a transportation hub. A microcell is usually larger than a picocell, though the distinction is not always clear...

  • CT2
    CT2
    CT2 is a cordless telephony standard that was used in the early 1990s to provide short-range proto-mobile phone service in some countries in Europe. It is considered the precursor to the popular DECT system...

     (DECT's predecessor)
  • WDECT
    Wideband Digital Enhanced Cordless Telecommunications
    Wideband Digital Enhanced Cordless Telecommunications, or simply WDECT, in mobile telephone technology, is similar to Digital Enhanced Cordless Telecommunications , except that it is a frequency hopping protocol. The protocol will jump pseudo-randomly between different parts of the 2.4 GHz radio...

  • Net3
    Net3
    Net3 was a Wifi-like system developed, manufactured and commercialised by Olivetti in the early 1990s. It could wirelessly connect PCs to an Ethernet fixed LAN at a speed of up to 512kb/s, over a very wide area...

  • Cat-iq
    CAT-iq
    CAT-iq stands for Cordless Advanced Technology—internet and quality and is a global technology initiative from the DECT Forum.-Background:...

  • Cordless telephone
    Cordless telephone
    A cordless telephone or portable telephone is a telephone with a wireless handset that communicates via radio waves with a base station connected to a fixed telephone line, usually within a limited range of its base station...


External links

The source of this article is wikipedia, the free encyclopedia.  The text of this article is licensed under the GFDL.
 
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