iPedia Free Information Center

Information about Dect

DECT or Digital Enhanced (formerly European) Cordless Telecommunications is an ETSI standard for digital portable phones, commonly used for domestic or corporate purposes. DECT can also be used for wireless data transfers. DECT is recognised 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-FT (Frequency Time).
Enlarge picture
The base unit and handset of a British Telecom DECT cordless telephone


DECT was developed by ETSI but has since been adopted by many countries all over the world. DECT is used in all countries in Europe, outside Europe it is used in most of Asia, Australia and South-America. As of 2005, the American Federal Communications Commission changed channelization and licensing costs in a portion of 1900 MHz range spectrum which allowed DECT devices to be used without expensive changes. DECT will operate as Unlicensed Personal Communications Services (UPCS).

Application

Connections with DECT is just for the communication between near located points and is not describing the network which is mostly behind. The connection to the network is realized with a gateway which is often named as base station. In most of the cases the connection is to the public switched telephone network. Also newer technologies like Voice over IP are known in the market. There are also devices available—like baby monitors—that do not need a gateway.

Features

Typical abilities of a domestic DECT Generic access profile (GAP) system include:
  • Multiple handsets to one base station and one phone line socket. Additional handsets usually have a battery charger station instead of a base station. The additional handsets do not require additional telephone sockets nor additional transceivers.
  • Interference-free wireless operation to around 100 metres outdoors. Operates clearly in common congested domestic radio traffic situations. For instance, generally immune to interference from WiFi or video senders.
  • Ability to make internal (intercom) calls between handsets.
Many DECT systems also include additional features such as Caller ID or a shared phonebook, but these are not standardized and may not work across different handset types.

Technical details

Some DECT properties:
  • Audio codec: G.726
  • Net bit rate: 32 kbit/s
  • Frequency: 1880-1900 MHz in Europe, 1920-1930MHz in the US
  • Carriers: 10 (1,728 kHz spacing) in Europe, 5 (1,728 kHz 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 uses: This means that the radio spectrum is divided into physical channels in two dimensions: frequency and time.

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

The DECT media access control layer is the layer which controls the physical layer and provides connection oriented, connectionless and broadcast services to the higher layers. It also provides encryption services with the DECT Standard Cipher (DSC).

The DECT data link layer uses a variant of the ISDN data link protocol called LACP. They are based on HDLC.

The DECT network layer 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 derived protocol. Many DECT-specific changes have been made.

There are four application areas in use in Europe:
  • Domestic DECTs are connected to a base (radio fixed parts) connected to the PSTN. A base can accept more DECT handsets.
  • Business DECTs connected to PBX. In such cases, there are many radio fixed parts. The DECT handsets dynamically connect to these using a handover feature.
  • Public DECT connected to the PSTN (very rare). A high density alternative to GSM.
  • Local loop (very rare). In this case, a DECT radio link replaces the normally wired connection between the final PSTN distribution point to the subscriber.
DECT GAP 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.

See also

References

  • Book: Cordless Telecommunications Worldwide, pub Springer 1996, ed WHW Tuttlebee
  • Book: Personal Wireless Communication with DECT and PWT, pub Artech 1998, J Philips & G MacNamee
  • Rechnernetze - The DECT Standard. (a summary of the DECT standard)

External links

A cordless telephone or portable telephone is a telephone with a wireless handset which communicates via radio waves with a base station connected to a fixed telephone line (POTS) and can only be operated near (typically within 100 meters or 328 ft from) its base station
..... Click the link for more information.
Itu is a municipality in the state of São Paulo in Brazil. The population in 2004 is 149,758 and the area is 641.68 km². The elevation is 583 m. This place name comes from the Tupi language.
..... Click the link for more information.
International Mobile Telecommunications-2000 (IMT-2000) is the global standard for third generation (3G) wireless communications as defined by the International Telecommunication Union. In 1999 ITU approved five radio interfaces for IMT-2000 as a part of the ITU-R M.
..... Click the link for more information.
    3G is the third generation of mobile phone standards and technology, after 2G. It is based on the International Telecommunication Union (ITU) family of standards under the International Mobile Telecommunications programme, "IMT-2000".
    ..... Click the link for more information.
    Federal Communications Commission

    Logo

    The FCC's official seal
    Agency overview
    Formed June 19, 1934
    Preceding Agencies Federal Radio Commission
     

    Annual Budget

    Agency Executive
    ..... Click the link for more information.
    Gateway has several meanings. It may often share meanings with the term gate.

    Music

    • Gateway a song by the symphonic black metal band Sathern (South Africa)
    • Gateway (album), an album by stoner metal band Bongzilla

    ..... Click the link for more information.
    The term base station can be used in the context of land surveying, wireless computer networking, 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
    ..... Click the link for more information.
    The public switched telephone network (PSTN) is the network of the world's public circuit-switched telephone networks, in much the same way that the Internet is the network of the world's public IP-based packet-switched networks.
    ..... Click the link for more information.
    Voice over Internet Protocol, also called VoIP, IP Telephony, Internet telephony, Broadband telephony, Broadband Phone and Voice over Broadband is the routing of voice conversations over the Internet or through any other IP-based network.
    ..... Click the link for more information.
    A typical baby monitor, also known as a baby alarm, is a simplex (uni-directional) transmitter and receiver system used to remotely listen for noises made by an infant.
    ..... Click the link for more information.
    Gateway has several meanings. It may often share meanings with the term gate.

    Music

    • Gateway a song by the symphonic black metal band Sathern (South Africa)
    • Gateway (album), an album by stoner metal band Bongzilla

    ..... Click the link for more information.
    This article is about the DECT standard. For other uses see Gap (disambiguation).


    The Generic Access Profile (GAP) (ETSI standard EN 300 444) describes a set of mandatory requirements to allow any conforming DECT Fixed Part (base) to inter operate with
    ..... Click the link for more information.
    This article is about a radio station in New Jersey. For the brand name used for wireless local area networks, see Wi-Fi.


    WIFI, 1460 AM, is a radio station broadcasting out of Florence, New Jersey. It has a Christian Contemporary format.
    ..... Click the link for more information.
    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 in the bedroom.
    ..... Click the link for more information.
    intercom (intercommunication device) is an electronic communications system within a building or group of buildings. Intercoms are generally composed of fixed microphone/speaker units which connect to a central control panel.
    ..... Click the link for more information.
    worldwide view of the subject.
    Please [ improve this article] or discuss the issue on the talk page.
    For the protein involved in the synthesis of major histocompatibility complex II, see CLIP (protein).

    ..... Click the link for more information.
    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.
    ..... Click the link for more information.
    hertz (symbol: Hz) is the SI unit of frequency. Its base unit is cycle/s or s-1 (also called inverse seconds, reciprocal seconds). In English, hertz is used as both singular and plural.
    ..... Click the link for more information.
    physical layer is level one in the seven-level OSI model of computer networking as well as in the five-layer TCP/IP reference model. It performs services requested by the data link layer.
    ..... Click the link for more information.
    This article or section is in need of attention from an expert on the subject.
    Please help recruit one or [ improve this article] yourself. See the talk page for details.
    ..... Click the link for more information.
    Time division multiple access (TDMA) is a channel access method for shared medium (usually radio) networks. It allows several users to share the same frequency channel by dividing the signal into different timeslots.
    ..... Click the link for more information.

    Time division duplex

    Time division duplex (TDD) is the application of time-division multiplexing to separate outward and return signals. It emulates full duplex communication over a half duplex communication link.
    ..... Click the link for more information.
    Radio frequency, or RF, is a frequency or rate of oscillation within the range of about 3 Hz and 300 GHz. This range corresponds to frequency of alternating current electrical signals used to produce and detect radio waves.
    ..... Click the link for more information.
    Media Access Control (MAC) data communication protocol sub-layer, also known as the Medium Access Control, is a part of the data link layer specified in the seven-layer OSI model (layer 2).
    ..... Click the link for more information.
    In telecommunications, connection-oriented describes a means of transmitting data in which the devices at the end points use a preliminary protocol to establish an end-to-end connection before any data is sent, and in which data is sent over the same path during the communication.
    ..... Click the link for more information.
    In a packet-switched network, connectionless mode transmission is a transmission in which each packet is prepended with a header containing a destination address sufficient to permit the independent delivery of the packet without the aid of additional instructions.
    ..... Click the link for more information.
    Broadcasting is the distribution of audio and/or video signals which transmit programs to an audience. The audience may be the general public or a relatively large sub-audience, such as children or young adults.
    ..... Click the link for more information.
    encryption is the process of transforming information (referred to as plaintext) to make it unreadable to anyone except those possessing special knowledge, usually referred to as a key.
    ..... Click the link for more information.
    data link layer is layer two of the seven-layer OSI model as well as of the five-layer TCP/IP reference model. It responds to service requests from the network layer and issues service requests to the physical layer.
    ..... Click the link for more information.
    Integrated Services Digital Network (ISDN) is a circuit-switched telephone network system, designed to allow digital transmission of voice and data over ordinary telephone copper wires, resulting in better quality and higher data speeds than are available with analog.
    ..... Click the link for more information.


    This article is copied from an article on Wikipedia.org - the free encyclopedia created and edited by online user community. The text was not checked or edited by anyone on our staff. Although the vast majority of the wikipedia encyclopedia articles provide accurate and timely information please do not assume the accuracy of any particular article. This article is distributed under the terms of GNU Free Documentation License.
    Herod_Archelaus


    page counter