DECT

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'''Digital enhanced cordless telecommunications (Digital European cordless telecommunications)'''
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'''Digital enhanced cordless telecommunications (Digital European cordless telecommunications)''',
 
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Originally designed as a cordless telephone standard to replace the half dozen different analog and digital cordless telephone technologies operating on various frequency bands from 1.6-1.7 MHz to 30-50 MHz (31 MHz in the UK, 43-50 MHz in the US) and UHF/SHF bands such as 890 MHz, 900 MHz band (902-928 MHz), the 2.4 GHz band 5 GHz band and 5.8 GHz bands among many others.
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usually known by the [[acronym]] '''DECT''', is a standard primarily used for creating [[cordless telephone]] systems. It originated in [[Europe]], where it is the universal standard, replacing earlier cordless phone standards, such as 900&nbsp;[[Hertz|MHz]] [[CT1]] and [[CT2]].<ref name=rohde>{{cite web |url=http://www2.rohde-schwarz.com/en/technologies/Wireless_Connectivity/DECT/information/ |title=DECT Information |website=2.rohde-schwarz.com |access-date=2 January 2018}}</ref>
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==Background==
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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&nbsp;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 universally replaced other standards in most countries where it is used, with the exception of North America.
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DECT Theory & Details
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Communication
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Typical Frequency Range is 1700-1940 MHz or 1.7 GHz to 1.94 GHz, usually simply referred to as 1.9 GHz band.
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General:
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Digital enhanced cordless telecommunications
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Modulation: TDMA, GMSK, GFSK
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Combination method. DECT uses MC (multi carrier): 10 RF channels; channel 10 at 1881.792 MHz; other channel numbers in decreasing order at 1.782 MHz intervals. DECT uses TDMA (time division multiple access) within a channel: 24 timeslots spaced 10 ms apart; 1 – 12 downlink, 13 – 24 uplink. DECT devices automatically look for the carrier that gives the best transmission quality (dynamic channel selection / allocation). DECT uses TDD (time division duplex) In full duplex mode for teleph-ony in 2 channels always separated by 5 ms and also on different frequencies. The bursts are GMSK or GFSK modulated (Gaussian minimum shift keying; Gaussian frequency shift keying). Up to 23 channels can be bundled for data transmissions. At least one channel must remain for the backward path
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DECT was originally intended for fast roaming between networked base stations, and the first DECT product was [[Net3|Net<sup>3</sup>]] wireless LAN. However, its most popular application is single-cell cordless phones connected to [[plain old telephone service|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 [[Business telephone system#Private branch exchange|private branch exchange]] (PBX) systems for medium and large businesses, produced by [[Panasonic]], [[Mitel]], [[Gigaset]], [[Snom]], [[BT Business]], [[Polycom|Spectralink]], and RTX Telecom. DECT can also be used for purposes other than cordless phones, such as [[baby monitor]]s and industrial sensors. The [[ULE Alliance]]'s [[DECT Ultra Low Energy|DECT ULE]] and its "HAN FUN" protocol<ref>''HAN FUN'', "Home Area Network FUNctional protocol".</ref> are variants tailored for home security, automation, and the [[internet of things]] (IoT).
 
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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.<ref>https://www.dect.org/</ref>
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usually known by the acronym '''DECT''',  or, in the United States, DECT 6.0, is a standard primarily used for creating [[cordless telephone]] systems. It originated in Europe and is now used worldwide (with frequency allocations differing from country to country...however, there are significant efforts at standardization as with LPD or [[Part 15]] devices in the EU (CEPT), etc.
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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]].
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==Frequencies==
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==Technical features==
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DECT bands DECT frequency bands DECT channels
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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 (telecommunications)|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.
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Typical abilities of a domestic DECT [[Generic access profile|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 jack. Additional handsets have a battery charger station that does not plug into the telephone system. Handsets can in many cases be used as [[intercom]]s, communicating between each other, and sometimes as [[walkie-talkie]]s, intercommunicating without telephone line connection.
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Full coverage usually considered 1770 MHz to 1939 MHz with obvious gaps depending on country allocation. Usually the 1.9 GHz band.  
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DECT operates in the 1880–1900&nbsp;MHz band and defines ten frequency channels from 1881.792&nbsp;MHz to 1897.344&nbsp;MHz with a band gap of 1728&nbsp;kHz.
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Channel spacing is usually 1.728 MHz, with some exceptions and offsets.  Power limits, duty cycle limitations and ERP/EIRP limits also vary from country to country.
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DECT operates as a multicarrier [[frequency division multiple access]] (FDMA) and [[time division multiple access]] (TDMA) system. This means that the [[radio spectrum]] is divided into physical carriers in two dimensions: frequency and time. FDMA access provides up to 10 frequency channels, and TDMA access provides 24 time slots per every frame of 10{{nbsp}}ms. DECT uses [[time division duplex]] (TDD), which means that down- and uplink use the same frequency but different time slots. Thus a base station provides 12 duplex speech channels in each frame, with each time slot occupying any available channel{{Snd}} thus 10&nbsp;×&nbsp;12&nbsp;=&nbsp;120 carriers are available, each carrying 32&nbsp;kbit/s.
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*1920 MHz - 1930 MHz - United States and Canada - DECT 6.0
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*1910 MHz - 1930 MHz - Latin America (excluding Brazil)  
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*1910 MHz - 1920 MHz - Brazil
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*1893 MHz - 1906 MHz - Japan - J-DECT specification
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*1786 MHz - 1792 MHz - South Korea
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*1880 MHz - 1900 MHz - Europe, most of Asia and numerous other countries - DECT-2020
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DECT also provides [[frequency-hopping spread spectrum]] over [[time division multiple access|TDMA]]/TDD structure for ISM band applications. If frequency-hopping is avoided, each base station can provide up to 120 channels in the DECT spectrum before frequency reuse. Each timeslot 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.<ref>{{Cite book|url=https://books.google.com/books?id=VmPT8B-5_tAC&pg=PA587|title=Wireless Communications: Principles And Practice, 2/E|last=S|first=Rappaport Theodore|date=September 2010|publisher=Pearson Education|isbn=978-81-317-3186-4|page=587}}</ref>
 
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DECT allows interference-free wireless operation to around {{convert|100|m|yd}} outdoors.  Indoor performance is reduced when interior spaces are constrained by walls.  
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DECT channel plan - ETSI standardization document - not all channels are authorized in all areas.
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DECT performs with fidelity in common congested domestic radio traffic situations. It is generally immune to interference from other DECT systems, [[Wi-Fi]] networks, [[video sender]]s, [[Bluetooth]] technology, baby monitors and other wireless devices.
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*Carrier ID 9 / Channel 9 - 1881.792 MHz
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*Carrier ID 8 / Channel 8 - 1883.592 MHz
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*Carrier ID 7 / Channel 7 - 1885.248 MHz
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*Carrier ID 6 / Channel 6 - 1886.876 MHz
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*Carrier ID 5 / Channel 5 - 1888.704 MHz
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*Carrier ID 4 / Channel 4 - 1890.432 MHz
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*Carrier ID 3 / Channel 3 - 1892.160 MHz
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*Carrier ID 2 / Channel 2 - 1893.888 MHz
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*Carrier ID 1 / Channel 1 - 1895.616 MHz
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*Carrier ID 0 / Channel 0 - 1897.344 MHz
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*Carrier ID 10 / Channel 10 - 1899.072 MHz
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*Carrier ID 11 / Channel 11 - 1900.800 MHz
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*Carrier ID 12 / Channel 12 - 1902.528 MHz
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*Carrier ID 13 / Channel 13 - 1904.256 MHz
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*Carrier ID 14 / Channel 14 - 1905.984 MHz
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*Carrier ID 15 / Channel 15 - 1907.712 MHz
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*Carrier ID 16 / Channel 16 - 1909.440 MHz
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*Carrier ID 17 / Channel 17 - 1911.168 MHz
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*Carrier ID 18 / Channel 18 - 1912.896 MHz
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*Carrier ID 19 / Channel 19 - 1914.624 MHz
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*Carrier ID 20 / Channel 20 - 1916.352 MHz
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*Carrier ID 21 / Channel 21 - 1918.080 MHz
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*Carrier ID 22 / Channel 22 - 1919.808 MHz
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*Carrier ID 23 / Channel 23 - 1921.536 MHz
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*Carrier ID 24 / Channel 24 - 1923.264 MHz
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*Carrier ID 25 / Channel 25 - 1924.992 MHz
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*Carrier ID 26 / Channel 26 - 1926.720 MHz
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*Carrier ID 27 / Channel 27 - 1928.448 MHz
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*Carrier ID 28 / Channel 28 - 1930.176 MHz
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*Carrier ID 29 / Channel 29 - 1931.904 MHz
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*Carrier ID 30 / Channel 30 - 1933.632 MHz
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*Carrier ID 31 / Channel 31 - 1935.360 MHz
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*Carrier ID 32 / Channel 32 - 1937.088 MHz
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===Technical properties===
 
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[[File:Pulse duration measurement of a DECT phone.jpg|thumb|250px|DECT pulse duration measurement (100{{nbsp}}Hz, 10{{nbsp}}ms) on channel 8]]
 
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ETSI standards documentation ETSI EN 300 175 parts 1–8 (DECT), ETSI EN 300 444 (GAP) and ETSI TS 102 527 parts 1–5 (NG-DECT) prescribe the following technical properties:
 
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* Audio codec:
 
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** mandatory:
 
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*** 32{{nbsp}}kbit/s [[G.726]] ADPCM (narrow band),
 
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*** 64{{nbsp}}kbit/s [[G.722]] sub-band ADPCM (wideband)
 
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** optional:
 
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*** 64{{nbsp}}kbit/s [[G.711]] μ-law/A-law PCM (narrow band),
 
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*** 32{{nbsp}}kbit/s [[G.729.1]] (wideband),
 
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*** 32{{nbsp}}kbit/s [[MPEG-4 Part 3|MPEG-4 ER AAC-LD]] (wideband),
 
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*** 64{{nbsp}}kbit/s MPEG-4 ER AAC-LD (super-wideband)
 
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* Frequency: the DECT physical layer specifies RF carriers for the frequency ranges 1880&nbsp;MHz to 1980&nbsp;MHz and 2010&nbsp;MHz to 2025&nbsp;MHz, as well as 902&nbsp;MHz to 928&nbsp;MHz and 2400&nbsp;MHz to 2483,5&nbsp;MHz [[ISM band]] with frequency-hopping for the U.S. market. The most common spectrum allocation is 1880&nbsp;MHz to 1900&nbsp;MHz; outside Europe, 1900&nbsp;MHz to 1920&nbsp;MHz and 1910&nbsp;MHz to 1930&nbsp;MHz spectrum is available in several countries. 
 
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** {{nowrap|1880–1900&nbsp;MHz}} in Europe, as well as South Africa, Asia, Hong Kong,<ref>{{cite web|title=Beware of Buying Radiocommunications Equipment not Meeting Prescribed Specifications|url=http://www.ofca.gov.hk/en/consumer_focus/education_corner/alerts/radiocomm/beware/index.html|publisher=Office of the Communications Authority}}</ref> Australia, and New Zealand
 
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** {{nowrap|1786–1792&nbsp;MHz}} in Korea
 
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** {{nowrap|1880–1895&nbsp;MHz}} in Taiwan
 
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** {{nowrap|1893–1906&nbsp;MHz}} (J-DECT) in Japan
 
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** {{nowrap|1900–1920&nbsp;MHz}} in China (until 2003){{citation needed|date=January 2017}}
 
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** {{nowrap|1910–1920&nbsp;MHz}} in Brazil
 
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** {{nowrap|1910–1930&nbsp;MHz}} in Latin America
 
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** {{nowrap|1920–1930&nbsp;MHz}} (DECT 6.0) in the United States and Canada
 
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* Carriers (1.728&nbsp;MHz spacing):
 
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** 10 channels in Europe and Latin America
 
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** 8 channels in Taiwan
 
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** 5 channels in the US, Brazil, Japan
 
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** 3 channels in Korea
 
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* Time slots: 2&nbsp;×&nbsp;12 (up and down stream)
 
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* Channel allocation: dynamic
 
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* Average transmission power: 10&nbsp;mW (250&nbsp;mW peak) in Europe & Japan, 4&nbsp;mW (100&nbsp;mW peak) in the US
 
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=== Physical layer ===
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[[Category: VHF/UHF Radio Services]]
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The DECT [[physical layer]] uses FDMA/TDMA access with TDD.
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[[Gaussian frequency-shift keying]] (GFSK) modulation is used: the binary one is coded with a frequency increase by 288&nbsp;kHz, and the binary zero with frequency decrease of 288&nbsp;kHz. With high quality connections, 2-, 4- or 8-level Differential PSK modulation (DBPSK, DQPSK or D8PSK), which is similar to QAM-2, QAM-4 and QAM-8, can be used to transmit 1, 2, or 3 bits per each symbol. QAM-16 and QAM-64 modulations with 4 and 8 bits per symbol can be used for user data (B-field) only, with resulting transmission speeds of up to 5,068{{nbsp}}Mbit/s.
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DECT provides dynamic channel selection and assignment; the choice of transmission frequency and time slot is always made by the mobile terminal. In case of interference in the selected frequency channel, the mobile terminal (possibly from suggestion by the base station) can initiate either intracell handover, selecting another channel/transmitter on the same base, or intercell handover, selecting a different base station altogether. For this purpose, DECT devices scan all idle channels at regular 30{{nbsp}}s intervals to generate a received signal strength indication (RSSI) list. When a new channel is required, the mobile terminal (PP) or base station (FP) selects a channel with the minimum interference from the RSSI list.
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The maximum allowed power for portable equipment as well as base stations is 250&nbsp;mW. A portable device radiates an average of about 10&nbsp;mW during a call as it is only using one of 24 time slots to transmit. In Europe, the power limit was expressed as [[effective radiated power]] (ERP), rather than the more commonly used [[equivalent isotropically radiated power]] (EIRP), permitting the use of high-gain directional antennas to produce much higher EIRP and hence long ranges.
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===Data link layer===
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The DECT [[media access control]] layer controls the physical layer and provides [[connection oriented]], [[connectionless]] and [[broadcasting|broadcast]] services to the higher layers.
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The DECT [[data link layer]] uses Link Access Protocol Control (LAPC), a specially designed variant of the [[Integrated Services Digital Network|ISDN]] data link protocol called LAPD. They are based on [[HDLC]].
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GFSK modulation uses a bit rate of 1152&nbsp;kbit/s, with a frame of 10{{nbsp}}ms (11520{{nbsp}}bits) which contains 24 time slots. Each slots contains 480 bits, some of which are reserved for physical packets and the rest is guard space. Slots 0–11 are always used for downlink (FP to PP) and slots 12–23 are used for uplink (PP to FP).
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There are several combinations of slots and corresponding types of physical packets with GFSK modulation:
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* Basic packet (P32){{Snd}} 420 or 424 bits "full slot", used for normal speech transmission. User data (B-field) contains 320 bits.
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* Low-capacity packet (P00){{Snd}} 96 bits at the beginning of the time slot ("short slot"). This packet only contains 64-bit header (A-field) used as a dummy bearer to broadcast base station identification when idle.
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* Variable capacity packet (P00''j''){{Snd}} 100&nbsp;+&nbsp;''j'' or 104&nbsp;+&nbsp;''j'' bits, either two half-slots (0&nbsp;≤&nbsp;''j''&nbsp;≤&nbsp;136) or "long slot" (137&nbsp;≤&nbsp;''j''&nbsp;≤&nbsp;856). User data (B-field) contains ''j'' bits.
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** P64 (''j''&nbsp;=&nbsp;640), P67 (''j''&nbsp;=&nbsp;672){{Snd}} "long slot", used by NG-DECT/CAT-iq wideband voice and data.
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* High-capacity packet (P80){{Snd}} 900 or 904 bits, "double slot". This packet uses two time slots and always begins in an even time slot. The B-field is increased to 800 bits..
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The 420/424 bits of a GFSK basic packet (P32) contain the following fields:
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* 32 bits{{Snd}} synchronization code (S-field): constant bit string AAAAE98AH for FP transmission, 55551675H for PP transmission
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* 388 bits{{Snd}} data (D-field), including
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** 64 bits{{Snd}} header (A-field): control traffic in logical channels C, M, N, P, and Q
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** 320 bits{{Snd}} user data (B-field): DECT payload, i.e. voice data
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** 4 bits{{Snd}} error-checking (X-field): CRC of the B-field
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* 4 bits{{Snd}} collision detection/channel quality (Z-field): optional, contains a copy of the X-field
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The resulting full data rate is 32&nbsp;kbit/s, available in both directions.
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===Network layer===
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The DECT [[network layer]] always contains the following protocol entities:
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* Call Control (CC)
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* Mobility Management (MM)
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Optionally it may also contain others:
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* Call Independent Supplementary Services (CISS)
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* Connection Oriented Message Service (COMS)
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* Connectionless Message Service (CLMS)
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All these communicate through a Link Control Entity (LCE).
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The call control protocol is derived from [[ISDN]] [[DSS1]], which is a [[Q.931]]-derived protocol. Many DECT-specific changes have been made.{{Specify|date=June 2010}}
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The mobility management protocol includes the management of identities, authentication, location updating, on-air subscription and key allocation. It includes many elements similar to the GSM protocol, but also includes elements unique to DECT.
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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 network design without breaking full interoperability.
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DECT [[Generic access profile|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. 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.
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===Security===
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The DECT media access control layer includes authentication of handsets to the base station using the DECT Standard Authentication Algorithm (DSAA). When registering the handset on the base, both record a shared 128-bit Unique Authentication Key (UAK). The base can request authentication by sending two random numbers to the handset, which calculates the response using the shared 128-bit key. The handset can also request authentication by sending a 64-bit random number to the base, which chooses a second random number, calculates the response using the shared key, and sends it back with the second random number.
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The standard also provides [[encryption]] services with the DECT Standard Cipher (DSC). The encryption is [[Key size|fairly weak]], using a 35-bit [[initialization vector]] and encrypting the voice stream with 64-bit encryption. While most of the DECT standard is publicly available, the part describing the DECT Standard Cipher was only available under a [[non-disclosure agreement]] to the phones' manufacturers from [[European Telecommunications Standards Institute|ETSI]].
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The properties of the DECT protocol make it hard to intercept a frame, modify it and send it later again, as DECT frames are based on time-division multiplexing and need to be transmitted at a specific point in time.<ref name=Tews-DECT-World-2016/> Unfortunately very few DECT devices on the market implemented authentication and encryption procedures<ref name=Tews-DECT-World-2016>Dr. DECT Secturity: Present, Past, Future. [http://www.dect.org/userfiles/file/DECT%20World%202016/Presentations/DF_DECT%20World%202016%20Presentations.zip DECT World 2016 Presentations]. Erik Tews, University of Birmingham. 31 May 2016.</ref><ref name="25c3"/>{{Snd}} and even when encryption was used by the phone, it was possible to implement a [[man-in-the-middle attack]] impersonating a DECT base station and revert to unencrypted mode{{Snd}} which allows calls to be listened to, recorded, and re-routed to a different destination.<ref name="25c3"/><ref name=RSA2009-DECT-Authentication>Lucks, Stefan; Schuler, Andreas; Tews, Erik; Weinmann, Ralf-Philipp; Wenzel, Matthias. [https://www.datenzone.de/blog/wp-content/uploads/2016/06/Attacks-on-the-DECT-authentication-mechanisms.pdf Attacks on the DECT Authentication Mechanisms]. Fischlin, Marc (Ed.): Topics in Cryptology{{Snd}} CT-RSA 2009, The Cryptographers' Track at the RSA Conference 2009, San Francisco, CA, USA, April 20–24, 2009.</ref><ref name=Tews-DECT-Security>Erik Tews. [http://tuprints.ulb.tu-darmstadt.de/2932/ DECT Security Analysis (Ph.D. Thesis)]. Technische Universität Darmstadt</ref>
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After an unverified report of a successful attack in 2002,<ref>{{cite newsgroup|message-id=adsq2u$p00$1@wanadoo.fr|newsgroup=alt.anonymous.messages|title=Do you like ice cream?|url=https://groups.google.com/group/alt.anonymous.messages/browse_thread/thread/d311d0ebbe503835/0e28cfbc393d174c|website=Groups.google.com|access-date=2 January 2018}}</ref><ref>{{cite web |url=http://lists.gnumonks.org/pipermail/dedected/2009-January/000432.html |title=DSC{{Snd}} Reverse Engineering of the Samsung DECT SP-R6150 |date=26 January 2009 |first=Ralf-Philipp |last=Weinmann  |url-status=dead  |archive-url=https://web.archive.org/web/20120226025256/http://lists.gnumonks.org/pipermail/dedected/2009-January/000432.html |archive-date=26 February 2012 |df=dmy }}</ref> members of the deDECTed.org project actually did reverse engineer the DECT Standard Cipher in 2008,<ref name="25c3">{{cite news | url = http://www.h-online.com/security/news/item/25C3-Serious-security-vulnerabilities-in-DECT-wireless-telephony-739493.html | title = Serious security vulnerabilities in DECT wireless telephony |publisher = Heise Online | date =29 December 2008 }}</ref> and as of 2010 there has been a viable attack on it that can recover the key.<ref name="DSC-analysis">{{cite web | url = https://www.datenzone.de/blog/wp-content/uploads/2016/06/Cryptanalysis-of-the-DECT-Standard-Cipher.pdf | title = Cryptanalysis of the DECT Standard Cipher | first1 = Karsten | last1 = Nohl | first2 = Erik | last2 = Tews | first3 = Ralf-Philipp | last3 = Weinmann | date =4 April 2010 |work=Fast Software Encryption, 17th International Workshop, FSE 2010, Seoul, Korea}}</ref>
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In 2012, an improved authentication algorithm, the DECT Standard Authentication Algorithm 2 (DSAA2), and improved version of the encryption algorithm, the DECT Standard Cipher 2 (DSC2), both based on [[Advanced Encryption Standard|AES]] 128-bit encryption, were included as optional in the NG-DECT/CAT-iq suite.
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DECT Forum also launched the DECT Security certification program which mandates the use of previously optional security features in the GAP profile, such as early encryption and base authentication.
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===Profiles===
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Various access profiles have been defined in the DECT standard:
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* Public Access Profile (PAP) (deprecated)
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* [[Generic access profile|Generic Access Profile]] (GAP){{Snd}} ETSI EN 300 444
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* Cordless Terminal Mobility (CTM) Access Profile (CAP){{Snd}} ETSI EN 300 824
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* Data access profiles
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** DECT Packet Radio System (DPRS){{Snd}} ETSI EN 301 649
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** DECT Multimedia Access Profile (DMAP)
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** Multimedia in the Local Loop Access Profile (MRAP)
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** Open Data Access Profile (ODAP)
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** [[Wireless local loop|Radio in the Local Loop]] (RLL) Access Profile (RAP){{Snd}} ETSI ETS 300 765
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* Interworking profiles (IWP)
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** DECT/[[Integrated Services Digital Network|ISDN]] Interworking Profile (IIP){{Snd}} ETSI EN 300 434
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** DECT/[[GSM Interworking Profile]] (GIP){{Snd}} ETSI EN 301 242
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** DECT/[[UMTS]] Interworking Profile (UIP){{Snd}} ETSI TS 101 863
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Latest revision as of 00:38, 5 June 2021

Digital enhanced cordless telecommunications (Digital European cordless telecommunications)


Originally designed as a cordless telephone standard to replace the half dozen different analog and digital cordless telephone technologies operating on various frequency bands from 1.6-1.7 MHz to 30-50 MHz (31 MHz in the UK, 43-50 MHz in the US) and UHF/SHF bands such as 890 MHz, 900 MHz band (902-928 MHz), the 2.4 GHz band 5 GHz band and 5.8 GHz bands among many others.

Background

DECT Theory & Details Communication Typical Frequency Range is 1700-1940 MHz or 1.7 GHz to 1.94 GHz, usually simply referred to as 1.9 GHz band. General: Digital enhanced cordless telecommunications Modulation: TDMA, GMSK, GFSK Combination method. DECT uses MC (multi carrier): 10 RF channels; channel 10 at 1881.792 MHz; other channel numbers in decreasing order at 1.782 MHz intervals. DECT uses TDMA (time division multiple access) within a channel: 24 timeslots spaced 10 ms apart; 1 – 12 downlink, 13 – 24 uplink. DECT devices automatically look for the carrier that gives the best transmission quality (dynamic channel selection / allocation). DECT uses TDD (time division duplex) In full duplex mode for teleph-ony in 2 channels always separated by 5 ms and also on different frequencies. The bursts are GMSK or GFSK modulated (Gaussian minimum shift keying; Gaussian frequency shift keying). Up to 23 channels can be bundled for data transmissions. At least one channel must remain for the backward path


usually known by the acronym DECT, or, in the United States, DECT 6.0, is a standard primarily used for creating cordless telephone systems. It originated in Europe and is now used worldwide (with frequency allocations differing from country to country...however, there are significant efforts at standardization as with LPD or Part 15 devices in the EU (CEPT), etc.

Frequencies

DECT bands DECT frequency bands DECT channels

Full coverage usually considered 1770 MHz to 1939 MHz with obvious gaps depending on country allocation. Usually the 1.9 GHz band.

Channel spacing is usually 1.728 MHz, with some exceptions and offsets. Power limits, duty cycle limitations and ERP/EIRP limits also vary from country to country.

  • 1920 MHz - 1930 MHz - United States and Canada - DECT 6.0
  • 1910 MHz - 1930 MHz - Latin America (excluding Brazil)
  • 1910 MHz - 1920 MHz - Brazil
  • 1893 MHz - 1906 MHz - Japan - J-DECT specification
  • 1786 MHz - 1792 MHz - South Korea
  • 1880 MHz - 1900 MHz - Europe, most of Asia and numerous other countries - DECT-2020


DECT channel plan - ETSI standardization document - not all channels are authorized in all areas.

  • Carrier ID 9 / Channel 9 - 1881.792 MHz
  • Carrier ID 8 / Channel 8 - 1883.592 MHz
  • Carrier ID 7 / Channel 7 - 1885.248 MHz
  • Carrier ID 6 / Channel 6 - 1886.876 MHz
  • Carrier ID 5 / Channel 5 - 1888.704 MHz
  • Carrier ID 4 / Channel 4 - 1890.432 MHz
  • Carrier ID 3 / Channel 3 - 1892.160 MHz
  • Carrier ID 2 / Channel 2 - 1893.888 MHz
  • Carrier ID 1 / Channel 1 - 1895.616 MHz
  • Carrier ID 0 / Channel 0 - 1897.344 MHz
  • Carrier ID 10 / Channel 10 - 1899.072 MHz
  • Carrier ID 11 / Channel 11 - 1900.800 MHz
  • Carrier ID 12 / Channel 12 - 1902.528 MHz
  • Carrier ID 13 / Channel 13 - 1904.256 MHz
  • Carrier ID 14 / Channel 14 - 1905.984 MHz
  • Carrier ID 15 / Channel 15 - 1907.712 MHz
  • Carrier ID 16 / Channel 16 - 1909.440 MHz
  • Carrier ID 17 / Channel 17 - 1911.168 MHz
  • Carrier ID 18 / Channel 18 - 1912.896 MHz
  • Carrier ID 19 / Channel 19 - 1914.624 MHz
  • Carrier ID 20 / Channel 20 - 1916.352 MHz
  • Carrier ID 21 / Channel 21 - 1918.080 MHz
  • Carrier ID 22 / Channel 22 - 1919.808 MHz
  • Carrier ID 23 / Channel 23 - 1921.536 MHz
  • Carrier ID 24 / Channel 24 - 1923.264 MHz
  • Carrier ID 25 / Channel 25 - 1924.992 MHz
  • Carrier ID 26 / Channel 26 - 1926.720 MHz
  • Carrier ID 27 / Channel 27 - 1928.448 MHz
  • Carrier ID 28 / Channel 28 - 1930.176 MHz
  • Carrier ID 29 / Channel 29 - 1931.904 MHz
  • Carrier ID 30 / Channel 30 - 1933.632 MHz
  • Carrier ID 31 / Channel 31 - 1935.360 MHz
  • Carrier ID 32 / Channel 32 - 1937.088 MHz



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