Las telecomunicaciones digitales inalámbricas mejoradas (Telecomunicaciones digitales europeas inalámbricas) , generalmente conocidas por el acrónimo DECT , son un estándar que se utiliza principalmente para crear sistemas telefónicos inalámbricos . Se originó en Europa , donde es el estándar universal, reemplazando los estándares anteriores de teléfonos inalámbricos, como 900 MHz CT1 y CT2 . [1]
Más allá de Europa, ha sido adoptado por Australia y la mayoría de los países de Asia y América del Sur . La adopción en América del Norte se retrasó por las regulaciones de radiofrecuencia de Estados Unidos . Este forzó el desarrollo de una variación de DECT llamada DECT 6.0 , utilizando un rango de frecuencia ligeramente diferente, lo que hace que estas unidades sean incompatibles con sistemas destinados a ser utilizados en otras áreas, incluso del mismo fabricante. DECT ha reemplazado casi universalmente a otros estándares en la mayoría de los países donde se usa, con la excepción de América del Norte.
DECT se diseñó originalmente para la itinerancia rápida entre estaciones base en red, y el primer producto DECT fue la red LAN inalámbrica Net 3 . Sin embargo, su aplicación más popular son los teléfonos inalámbricos de una sola celda conectados a teléfonos analógicos tradicionales , principalmente en sistemas domésticos y de oficinas pequeñas, aunque las puertas de enlace con repetidores DECT y / o DECT de varias celdas también están disponibles en muchas centrales privadas (PBX). sistemas para medianas y grandes empresas, producidos por Panasonic , Mitel , Gigaset , Snom , Spectralink y RTX Telecom. DECT también se puede utilizar para fines distintos a los teléfonos inalámbricos, como monitores para bebés y sensores industriales. La Alianza ULE 's DECT ULE y su protocolo 'HAN diversión' [2] son variantes adaptadas para la seguridad en el hogar, la automatización y la Internet de las cosas (IoT).
El estándar DECT incluye el perfil de acceso genérico (GAP), un perfil de interoperabilidad común para capacidades telefónicas simples, que implementan la mayoría de los fabricantes. La conformidad con GAP permite que los terminales y bases DECT de diferentes fabricantes interoperen en el nivel más básico de funcionalidad, el de realizar y recibir llamadas. Japón utiliza su propia variante DECT, J-DECT, que es compatible con el foro DECT. [3]
El estándar DECT de nueva generación (NG-DECT), comercializado como CAT-iq por el DECT Forum, proporciona un conjunto común de capacidades avanzadas para teléfonos y estaciones base. CAT-iq permite la intercambiabilidad entre estaciones base IP-DECT y teléfonos de diferentes fabricantes, al tiempo que mantiene la compatibilidad con equipos GAP. También requiere soporte obligatorio para audio de banda ancha .
Historia de los estándares
El estándar DECT fue desarrollado por ETSI en varias fases, la primera de las cuales tuvo lugar entre 1988 y 1992 cuando se publicó la primera ronda de estándares. Se trata de la serie ETS 300-175 en nueve partes que definen la interfaz aérea, y ETS 300-176 que define cómo deben homologarse las unidades. También se publicó un informe técnico, ETR-178, para explicar el estándar. [4] El ETSI desarrolló y publicó normas posteriores para cubrir los perfiles de interoperabilidad y las normas para las pruebas.
Nombrado teléfono digital inalámbrico europeo en su lanzamiento por CEPT en noviembre de 1987; su nombre pronto fue cambiado a Telecomunicaciones Inalámbricas Digitales Europeas, siguiendo una sugerencia de Enrico Tosato de Italia, para reflejar su gama más amplia de aplicaciones, incluidos los servicios de datos. En 1995, debido a su uso más global, el nombre se cambió de europeo a mejorado. La UIT reconoce que DECT cumple los requisitos de las IMT-2000 y, por lo tanto, califica como un sistema 3G . Dentro del grupo de tecnologías IMT-2000, DECT se conoce como tiempo de frecuencia IMT-2000 (IMT-FT).
DECT fue desarrollado por ETSI, pero desde entonces ha sido adoptado por muchos países de todo el mundo. La banda de frecuencia DECT original (1880-1900 MHz) se utiliza en todos los países de Europa . Fuera de Europa, se utiliza en la mayor parte de Asia , Australia y América del Sur . En los Estados Unidos , la Comisión Federal de Comunicaciones en 2005 cambió los costos de canalización y licencia en una banda cercana (1920-1930 MHz, o 1.9 GHz ), conocida como Servicios de Comunicaciones Personales Sin Licencia (UPCS), permitiendo la venta de dispositivos DECT en los EE. UU. con solo cambios mínimos. Estos canales están reservados exclusivamente para aplicaciones de comunicación de voz y, por lo tanto, es menos probable que experimenten interferencias de otros dispositivos inalámbricos como monitores de bebés y redes inalámbricas .
El estándar DECT de nueva generación ( NG-DECT ) se publicó por primera vez en 2007; [5] fue desarrollado por ETSI con la orientación de la Home Gateway Initiative a través del DECT Forum [6] para apoyar las funciones IP-DECT en equipos de gateway doméstico / IP-PBX . La serie ETSI TS 102 527 viene en cinco partes y cubre el audio de banda ancha y las características de interoperabilidad obligatorias entre los teléfonos y las estaciones base. Fueron precedidos por un informe técnico explicativo, ETSI TR 102 570. [7] El Foro DECT mantiene el programa de certificación y marca registrada CAT-iq ; El perfil de voz de banda ancha CAT-iq 1.0 y los perfiles de interoperabilidad 2.0 / 2.1 se basan en las partes relevantes de ETSI TS 102527.
El estándar DECT Ultra Low Energy (DECT ULE) se anunció en enero de 2011 y los primeros productos comerciales fueron lanzados ese mismo año por Dialog Semiconductor . El estándar fue creado para permitir aplicaciones de monitoreo de energía, seguridad, salud y automatización del hogar que funcionan con baterías. Al igual que DECT, el estándar DECT ULE utiliza la banda de 1,9 GHz y, por lo tanto, sufre menos interferencias que Zigbee , Bluetooth o Wi-Fi de los hornos microondas, que funcionan en la banda ISM de 2,4 GHz sin licencia . DECT ULE utiliza una topología de red en estrella simple, por lo que muchos dispositivos en el hogar están conectados a una sola unidad de control.
Se ha agregado un nuevo códec de audio de baja complejidad, LC3plus, como una opción a la revisión de 2019 del estándar DECT. Este códec está diseñado para aplicaciones de música y voz de alta calidad, y admite codificación escalable de banda estrecha, banda ancha, banda súper ancha y banda completa, con frecuencias de muestreo de 8, 16, 24, 32 y 48 kHz y un ancho de banda de audio de hasta 20 kHz. [8]
El nuevo protocolo de radio DECT-2020 se publicó en julio de 2020; define una nueva interfaz física basada en multiplexación por división de frecuencia ortogonal de prefijo cíclico (CP- OFDM ) capaz de una velocidad de transferencia de hasta 1,2 Gbit / s con modulación QAM- 1024. El estándar actualizado admite MIMO de múltiples antenas y formación de haces , codificación de canal FEC y solicitud de repetición automática híbrida . Define 17 frecuencias de canales de radio en el rango de 450 MHz hasta 5 875 MHz, y anchos de banda de canal de 1728, 3456 o 6912 kHz. La comunicación directa entre dispositivos finales es posible con una topología de red en malla . ETSI propuso el protocolo DECT-2020 actualizado como candidato para el próximo estándar IMT-2020 , para su uso en la automatización de la industria de comunicaciones de tipo de máquina masiva (MMTC), comunicaciones de baja latencia ultraconfiables (URLLC) y aplicaciones de audio inalámbrico profesional con punto -Comunicaciones de multidifusión o punto a punto ; [9] [10] [11] la revisión de la propuesta presentada se completará en octubre de 2021. [12] El comité ESTI DECT también consideró las modulaciones OFDMA y SC-FDMA . [13] [14]
OpenD es un marco de código abierto diseñado para proporcionar una implementación de software completa de los protocolos DECT ULE en hardware de referencia de Dialog Semiconductor y DSP Group ; el proyecto es mantenido por el foro DECT. [15] [16]
Solicitud
The DECT standard originally envisaged three major areas of application:[4]
- 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.
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 launched a wide-area DECT network known as "Fido" after much regulatory delay, covering major cities in Italy.[17] The service was promoted for only a few months and, having peaked at 142,000 subscribers, was shut down in 2001.[18]
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 10 kilometres (6.2 mi). 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[19] also exist, but have been eclipsed by Wi-Fi, 3G and 4G which compete with DECT for both voice and data.
DECT 6.0
DECT 6.0 is a North American marketing term for DECT devices manufactured for the United States and Canada operating at 1.9 GHz. The "6.0" does not equate to a spectrum band; it was 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 term was coined by Rick Krupka, marketing director at Siemens and the DECT USA Working Group / Siemens ICM.
In North America, DECT suffers from deficiencies in comparison to DECT elsewhere, since the UPCS band (1920–1930 MHz) is not free from heavy interference.[20] Bandwidth is half as wide as that used in Europe (1880–1900 MHz), the 4 mW average transmission power reduces range compared to the 10 mW permitted in Europe, and the commonplace lack of GAP compatibility among US vendors binds customers to a single vendor.
Before 1.9 GHz band was approved by the FCC in 2005, DECT could only operate in unlicensed 2.4 GHz and 900 MHz Region 2 ISM bands; some users of Uniden WDECT 2.4 GHz phones reported interoperability issues with Wi-Fi equipment.[21][22][unreliable source?]
North-American DECT 6.0 products may not be used in Europe, Pakistan,[23] Sri Lanka,[24] and Africa, as they cause and suffer from interference with the local cellular networks. Use of such products is prohibited by European Telecommunications Authorities, PTA, Telecommunications Regulatory Commission of Sri Lanka[25] and the Independent Communication Authority of South Africa. European DECT products may not be used in the United States and Canada, as they likewise cause and suffer from interference with American and Canadian cellular networks, and use is prohibited by the Federal Communications Commission and Industry Canada.
DECT 8.0 HD is a marketing designation for North American DECT devices certified with CAT-iq 2.0 "Multi Line" profile.[26]
NG-DECT / CAT-iq
Cordless Advanced Technology—internet and quality (CAT-iq) is a certification program maintained by the DECT Forum. It is based on New Generation DECT (NG-DECT) series of standards from ETSI.
NG-DECT/CAT-iq contains features that expand the generic GAP profile with mandatory support for high quality wideband voice, enhanced security, calling party identification, multiple lines, parallel calls, and similar functions to facilitate VoIP calls through SIP and H.323 protocols.
There are several CAT-iq profiles which define supported voice features:
- CAT-iq 1.0 – "HD Voice" (ETSI TS 102 527-1): wideband audio, calling party line and name identification (CLIP/CNAP)
- CAT-iq 2.0 – "Multi Line" (ETSI TS 102 527-3): multiple lines, line name, call waiting, call transfer, phonebook, call list, DTMF tones, headset, settings
- CAT-iq 2.1 – "Green" (ETSI TS 102 527-5): 3-party conference, call intrusion, caller blocking (CLIR), answering machine control, SMS, power-management
- CAT-iq Data – light data services, software upgrade over the air (SUOTA) (ETSI TS 102 527-4)
- CAT-iq IOT – Smart Home connectivity (IOT) with DECT Ultra Low Energy (ETSI TS 102 939)
CAT-iq allows any DECT handset to communicate with a DECT base from a different vendor, providing full interoperability. CAT-iq 2.0/2.1 feature set is designed to support IP-DECT base stations found in office IP-PBX and home gateways.
Características técnicas
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 jack. 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.
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 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 – thus 10 × 12 = 120 carriers are available, each carrying 32 kbit/s.
DECT also provides frequency-hopping spread spectrum over 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.[27]
DECT allows interference-free wireless operation to around 100 metres (110 yd) outdoors. Indoor performance is reduced when interior spaces are constrained by walls.
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 senders, Bluetooth technology, baby monitors and other wireless devices.
Technical properties
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:
- Audio codec:
- mandatory:
- 32 kbit/s G.726 ADPCM (narrow band),
- 64 kbit/s G.722 sub-band ADPCM (wideband)
- optional:
- 64 kbit/s G.711 μ-law/A-law PCM (narrow band),
- 32 kbit/s G.729.1 (wideband),
- 32 kbit/s MPEG-4 ER AAC-LD (wideband),
- 64 kbit/s MPEG-4 ER AAC-LD (super-wideband)
- mandatory:
- Frequency: the DECT physical layer specifies RF carriers for the frequency ranges 1880 MHz to 1980 MHz and 2010 MHz to 2025 MHz, as well as 902 MHz to 928 MHz and 2400 MHz to 2483,5 MHz ISM band with frequency-hopping for the U.S. market. The most common spectrum allocation is 1880 MHz to 1900 MHz; outside Europe, 1900 MHz to 1920 MHz and 1910 MHz to 1930 MHz spectrum is available in several countries.
- 1880–1900 MHz in Europe, as well as South Africa, Asia, Hong Kong,[28] Australia, and New Zealand
- 1786–1792 MHz in Korea
- 1880–1895 MHz in Taiwan
- 1893–1906 MHz (J-DECT) in Japan
- 1900–1920 MHz in China (until 2003)[citation needed]
- 1910–1920 MHz in Brazil
- 1910–1930 MHz in Latin America
- 1920–1930 MHz (DECT 6.0) in the United States and Canada
- Carriers (1.728 MHz spacing):
- 10 channels in Europe and Latin America
- 8 channels in Taiwan
- 5 channels in the US, Brazil, Japan
- 3 channels in Korea
- Time slots: 2 × 12 (up and down stream)
- Channel allocation: dynamic
- Average transmission power: 10 mW (250 mW peak) in Europe & Japan, 4 mW (100 mW peak) in the US
Physical layer
The DECT physical layer uses FDMA/TDMA access with TDD.
Gaussian frequency-shift keying (GFSK) modulation is used: the binary one is coded with a frequency increase by 288 kHz, and the binary zero with frequency decrease of 288 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 Mbit/s.
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 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.
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. 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.
Data link layer
The DECT media access control layer controls the physical layer and provides connection oriented, connectionless and broadcast services to the higher layers.
The DECT data link layer uses Link Access Protocol Control (LAPC), a specially designed variant of the ISDN data link protocol called LAPD. They are based on HDLC.
GFSK modulation uses a bit rate of 1152 kbit/s, with a frame of 10 ms (11520 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).
There are several combinations of slots and corresponding types of physical packets with GFSK modulation:
- Basic packet (P32) – 420 or 424 bits "full slot", used for normal speech transmission. User data (B-field) contains 320 bits.
- Low-capacity packet (P00) – 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.
- Variable capacity packet (P00j) – 100 + j or 104 + j bits, either two half-slots (0 ≤ j ≤ 136) or "long slot" (137 ≤ j ≤ 856). User data (B-field) contains j bits.
- P64 (j = 640), P67 (j = 672) – "long slot", used by NG-DECT/CAT-iq wideband voice and data.
- High-capacity packet (P80) – 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..
The 420/424 bits of a GFSK basic packet (P32) contain the following fields:
- 32 bits – synchronization code (S-field): constant bit string AAAAE98AH for FP transmission, 55551675H for PP transmission
- 388 bits – data (D-field), including
- 64 bits – header (A-field): control traffic in logical channels C, M, N, P, and Q
- 320 bits – user data (B-field): DECT payload, i.e. voice data
- 4 bits – error-checking (X-field): CRC of the B-field
- 4 bits – collision detection/channel quality (Z-field): optional, contains a copy of the X-field
The resulting full data rate is 32 kbit/s, available in both directions.
Network layer
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.[specify]
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.
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.
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. 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 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.
The standard also provides encryption services with the DECT Standard Cipher (DSC). The encryption is 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 ETSI.
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.[29] Unfortunately very few DECT devices on the market implemented authentication and encryption procedures[29][30] – 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 – which allows calls to be listened to, recorded, and re-routed to a different destination.[30][31][32]
After an unverified report of a successful attack in 2002,[33][34] members of the deDECTed.org project actually did reverse engineer the DECT Standard Cipher in 2008,[30] and as of 2010 there has been a viable attack on it that can recover the key.[35]
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 AES 128-bit encryption, were included as optional in the NG-DECT/CAT-iq suite.
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.
Profiles
Various access profiles have been defined in the DECT standard:
- Public Access Profile (PAP) (deprecated)
- Generic Access Profile (GAP) – ETSI EN 300 444
- Cordless Terminal Mobility (CTM) Access Profile (CAP) – ETSI EN 300 824
- Data access profiles
- DECT Packet Radio System (DPRS) – ETSI EN 301 649
- DECT Multimedia Access Profile (DMAP)
- Multimedia in the Local Loop Access Profile (MRAP)
- Open Data Access Profile (ODAP)
- Radio in the Local Loop (RLL) Access Profile (RAP) – ETSI ETS 300 765
- Interworking profiles (IWP)
- DECT/ISDN Interworking Profile (IIP) – ETSI EN 300 434
- DECT/GSM Interworking Profile (GIP) – ETSI EN 301 242
- DECT/UMTS Interworking Profile (UIP) – ETSI TS 101 863
DECT para redes de datos
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 metres (660 ft) indoors and 6 kilometres (3.7 mi) 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.[36] 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, 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 technically competitive wireless data transport had passed.
Salud y seguridad
DECT uses UHF radio, similar to mobile phones, baby monitors, Wi-Fi, and other cordless telephone technologies. The UK Health Protection Agency (HPA) claims that due to a mobile phone's adaptive power ability, a DECT cordless phone's radiation could actually exceed the radiation of a mobile phone. A DECT cordless phone's radiation has an average output power of 10 mW but is in the form of 100 bursts per second of 250 mW, a strength comparable to some mobile phones.[37] Most studies have been unable to demonstrate any link to health effects, or have been inconclusive. Electromagnetic fields may have an effect on protein expression in laboratory settings[38] but have not yet been demonstrated to have clinically significant effects in real-world settings. The World Health Organization has issued a statement on medical effects of mobile phones which acknowledges that the longer term effects (over several decades) require further research.[39]
Ver también
- GSM Interworking Profile (GIP)
- IP-DECT
- CT2 (DECT's predecessor in Europe)
- Net3
- CorDECT
- WDECT
- Unlicensed Personal Communications Services
- Microcell
- Wireless local loop
Referencias
- ^ "DECT Information". 2.rohde-schwarz.com. Retrieved 2 January 2018.
- ^ HAN FUN, "Home Area Network FUNctional protocol".
- ^ https://www.dect.org/
- ^ a b "ETSI TR 101 178 V1.5.1 (2005-02). Digital Enhanced Cordless Telecommunications (DECT): A high level guide to the DECT standardization" (PDF). Etsi.org. Retrieved 2 January 2018.
- ^ "DECT reaches a New Generation". Etsi.org. Retrieved 2 January 2018.
- ^ "DECT Issue 006 – October 2016". Dect.org. Retrieved 2 January 2018.
- ^ "ETSI TR 102 570 V1.1.1 (2007-03). Digital Enhanced Cordless Telecommunications (DECT); New Generation DECT; Overview and Requirements" (PDF). Etsi.org. Retrieved 2 January 2018.
- ^ ETSI TS 103 634 V1.1.1 (2019-08): Low Complexity Communication Codec plus (LC3plus)
- ^ DECT Today (May 2018)
- ^ ETSI TR 103 515 V1.1.1 (2018-03): Study on URLLC use cases of vertical industries for DECT evolution and DECT-2020
- ^ ETSI TR 103 635 V1.1.1 (2019-11): DECT-2020 New Radio (NR) interface; Study on MAC and higher layers
- ^ 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
- ^ ETSI TR 103 422 V1.1.1 (2017-06): Requirements and technical analysis for the further evolution of DECT and DECT ULE
- ^ ETSI TR 103 513 V1.1.1 (2019-11): DECT Technology Roadmap
- ^ http://opend.dect.org
- ^ https://stackforce.github.io/opend-doc/
- ^ DECT for Cordless Terminal Mobility. DECT Forum Newsletter. 6 March 1998
- ^ "La TELECOM spegne "Fido" – 5 aprile 2000". Angelodenicola.it. Retrieved 2 January 2018.
- ^ Schuler, Andreas; Tews, Erik; Weinmann, Ralf-Philipp (29 December 2008). "What is DECT?" (PDF). deDECTed.org. Archived from the original (PDF) on 5 October 2016. Retrieved 15 September 2016.
- ^ "DECT Frequencies, Channels, Frequency Bands | Electronics Notes". www.electronics-notes.com. Retrieved 26 May 2020.
- ^ "WDECT Phone review". Archived from the original on 27 February 2009. Retrieved 3 June 2018.
- ^ Example of WI-FI and WDECT problems
- ^ "Lists of Illegal and Legal Cordless Phones". PTA. 10 December 2015. Retrieved 27 December 2019.
- ^ Daily Mirror. "TRC Seizes Wireless Phones". Daily Mirror. Retrieved 8 July 2017.
- ^ TRCSL. "The Use of DECT 6.0 Phones is illegal in Sri Lanka". TRCSL. TRCSL. Retrieved 8 July 2017.
- ^ "DECT Today, Issue 8". Newsletter.insight5.nl. October 2017. p. 16. Retrieved 2 January 2018.
- ^ S, Rappaport Theodore (September 2010). Wireless Communications: Principles And Practice, 2/E. Pearson Education. p. 587. ISBN 978-81-317-3186-4.
- ^ "Beware of Buying Radiocommunications Equipment not Meeting Prescribed Specifications". Office of the Communications Authority.
- ^ a b Dr. DECT Secturity: Present, Past, Future. DECT World 2016 Presentations. Erik Tews, University of Birmingham. 31 May 2016.
- ^ a b c "Serious security vulnerabilities in DECT wireless telephony". Heise Online. 29 December 2008.
- ^ Lucks, Stefan; Schuler, Andreas; Tews, Erik; Weinmann, Ralf-Philipp; Wenzel, Matthias. Attacks on the DECT Authentication Mechanisms. Fischlin, Marc (Ed.): Topics in Cryptology – CT-RSA 2009, The Cryptographers' Track at the RSA Conference 2009, San Francisco, CA, USA, April 20–24, 2009.
- ^ Erik Tews. DECT Security Analysis (Ph.D. Thesis). Technische Universität Darmstadt
- ^ "Do you like ice cream?". Groups.google.com. Newsgroup: alt.anonymous.messages. Usenet: [email protected]. Retrieved 2 January 2018.
- ^ Weinmann, Ralf-Philipp (26 January 2009). "DSC – Reverse Engineering of the Samsung DECT SP-R6150". Archived from the original on 26 February 2012.
- ^ Nohl, Karsten; Tews, Erik; Weinmann, Ralf-Philipp (4 April 2010). "Cryptanalysis of the DECT Standard Cipher" (PDF). Fast Software Encryption, 17th International Workshop, FSE 2010, Seoul, Korea.
- ^ "Wireless LANs: developments in technology and standards". IEE Journal of Computing and Control Engineering. October 1994.
- ^ Independent Advisory Group on Non-ionising Radiation (April 2012). "Health Effects from Radiofrequency Electromagnetic Fields". (UK) Health Protection Agency. Retrieved 10 September 2013.
- ^ Vitreous State Laboratory, Catholic University of America, Washington, DC 20064, USA. (2002). "Chronic electromagnetic field exposure decreases HSP70 levels and lowers cytoprotection". Journal of Cellular Biochemistry. (US) Wiley-Liss, Inc. 84 (3): 447–54. doi:10.1002/jcb.10036. PMID 11813250. S2CID 45020298.CS1 maint: multiple names: authors list (link)
- ^ "What are the health risks associated with mobile phones and their base stations?". Online Q&A. World Health Organization. 5 December 2005. Retrieved 19 January 2008.
Estándares
- ETSI EN 300 175 V2.8.1 (2019-12). Digital Enhanced Cordless Telecommunications (DECT) – Common Interface (CI)
- ETSI EN 300 175-1. Part 1: Overview
- ETSI EN 300 175-2. Part 2: Physical Layer (PHL)
- ETSI EN 300 175-3. Part 3: Medium Access Control (MAC) layer
- ETSI EN 300 175-4. Part 4: Data Link Control (DLC) layer
- ETSI EN 300 175-5. Part 5: Network (NWK) layer
- ETSI EN 300 175-6. Part 6: Identities and addressing
- ETSI EN 300 175-7. Part 7: Security features
- ETSI EN 300 175-8. Part 8: Speech and audio coding and transmission
- ETSI TS 102 939. Digital Enhanced Cordless Telecommunications (DECT) – Ultra Low Energy (ULE) – Machine to Machine Communications
- ETSI TS 102 939-1 V1.3.1 (2017-10). Part 1: Home Automation Network (phase 1)
- ETSI TS 102 939-2 V1.3.1 (2019-01). Part 2: Home Automation Network (phase 2)
- ETSI TS 102 527. Digital Enhanced Cordless Telecommunications (DECT) – New Generation DECT
- ETSI TS 102 527-1 V1.5.1 (2019-08). Part 1: Wideband speech
- ETSI TS 102 527-2 V1.1.1 (2007-06). Part 2: Support of transparent IP packet data
- ETSI TS 102 527-3 V1.7.1 (2019-08). Part 3: Extended wideband speech services
- ETSI TS 102 527-4 V1.3.1 (2015-11). Part 4: Light Data Services; Software Update Over The Air (SUOTA), content downloading and HTTP based applications
- ETSI TS 102 527-5 V1.4.1 (2019-08). Part 5: Additional feature set nr. 1 for extended wideband speech services
- ETSI TS 103 636 v1.1.1 (2020-07). DECT-2020 New Radio (NR)
- ETSI TS 103 636-1. Part 1: Overview
- ETSI TS 103 636-2. Part 2: Radio reception and transmission requirements
- ETSI TS 103 636-3. Part 3: Physical layer
- ETSI TS 103 636-4. Part 4: MAC layer
- Digital Enhanced Cordless Telecommunications (DECT)
- ETSI TS 103 634 V1.2.1 (2020-10). Low Complexity Communication Codec plus (LC3plus)
- ETSI EN 300 444 V2.5.1 (2017-10). Generic Access Profile (GAP)
- ETSI EN 300 824 V1.3.1 (2001-08). Cordless Terminal Mobility (CTM) – CTM Access Profile (CAP)
- ETSI EN 300 700 V2.2.1 (2018-12). Wireless Relay Station (WRS)
- ETSI EN 301 649 V2.3.1 (2015-03). DECT Packet Radio Service (DPRS)
- ETSI EN 300 757 V1.5.1 (2004-09). Low Rate Messaging Service (LRMS) including Short Messaging Service (SMS)
- Digital Enhanced Cordless Telecommunications (DECT) – New Generation DECT
- ETSI TS 102 841 V1.5.1 (2014-01). Extended wideband speech services – Profile Test Specification (PTS) and Test Case Library (TCL)
- ETSI TS 102 843 V1.1.1 (2014-01). Additional feature set nr.1 for extended wideband speech services; Profile Test Specification (PTS) and Test Case Library (TCL)
- ETSI TS 103 158 V1.1.1 (2014-11). Light Data Services – Software Update Over The Air (SUOTA) – Profile Test Specification (PTS) and Test Case Library (TCL)
Otras lecturas
- Tuttlebee, Wally H.W. (1996). Cordless Telecommunications Worldwide. Springer. ISBN 978-3-540-19970-0.
- Phillips, John A.; Mac Namee, Gerard (1998). Personal Wireless Communication with DECT and PWT. Artech. ISBN 978-0-89006-872-4.
- Prof. Dr. W. Kowalk (13 March 2007). "Rechnernetze – The DECT Standard". Retrieved 29 December 2008.
- Technical Report: Multicell Networks based on DECT and CAT-iq. Dosch & Amand Research
enlaces externos
- DECT Forum at dect.org
- DECT information at ETSI
- DECTWeb.com
- Open source implementation of a DECT stack