Issued by: Teleconformity
Number: TCMY-025
Publication date: 2011-02-25
Author: CEO

Digital Enhanced Cordless Telecommunications (DECT), background & Technology

DECT is a technology standard for short-range cordless communications, which can be adapted for many applications and can be used over unlicensed frequency allocations world-wide. DECT is suited to voice (including PSTN and VoIP telephony), data and networking applications with a range up to 500 metres. DECT was initially developed as a European standard. It was later adopted by many other countries and today has become a word-wide de-facto standard for cordless telephony applications. Currently, DECT is available almost worldwide (the technology has been adopted in over 110 countries). The United States market was, in practice, opened to DECT by an FCC decision in 2005, and is now one of the most important markets in terms of growing. Even South Korea (a traditional Japan influence area) is open to DECT. Currently Japan has its own technology for the application (PHS), but there are negotiations ongoing to allow also the introduction of DECT in Japan.

Europe
The most common spectrum allocation for DECT is 1880MHz to 1900MHz used in Europe and many other countries outside Europe. In Europe, this spectrum is unlicensed and technology exclusive, what ensures an interference free operation, and contributes to the very high spectral efficiency of the technology. The Regulatory standards for DECT in Europe can be found below.
Frequency allocations in Europe of 1900-1920 (shared with UTRAN TDD), 1920-1980MHz (shared with the uplink of UTRAN FDD) and 2010-2025MHz have been foreseen by IMT-2000 for potential expansion of the standard (see EN 301 908-10 ), but actually they are not used yet.

Outside Europe
The bands 1900MHz to 1920MHz and 1910MHz to 1930MHz are also very common in many countries outside Europe. 1900MHz to 1920MHz was originally developed for China first, whereas 1910MHz to 1930MHz was originally most used in south and latin America, but also the US and Canada now.

United States
In the USA the frequency allocation is 1920-1930MHz, known as UPCS band (FCC subpart D testing) with special requirements in 15.323 . In this case, the allocation is not technology exclusive, but is, in practice, enough "clean", to achieve similar interference-free operation. Because this band in the US was used for other services, manufacturers of DECT equipment have to contribute in conpensating previous users in this band and pay a clearing fee to (a contract with) UTAM . At time of writing this article, the entry fee is usd $ 50,000 and a fee for each unit marketed. When applying a DECT device for FCC certification, a UTAM statement (letter) shall be included, however please always check the latest situation w.r.t UTAM and it's state of play.
Be aware that in the US, 450MHz CDMA technology and 2.4GHz DTS/DSS technology is also often used in cordless phones and called DECT, but as it might be clear, it is not using DECT technology in these frequency bands. Note that the PSTN interface (usually the base station side) requires ACTA or ("part 68") approval, which Teleconformity can also provide.

Canada
See Industry Canada standard RSS-213 for the Radio part. Note that the PSTN interface (usually the base station side) requires IC-03 ("IC TTE / TAPAC") approval, which Teleconformity can also provide.

The technology and state of play
DECT uses Multi carrier TDMA technology with TDD (time division duplex), a Frame time 10ms with 24 (2x12) number of slots per frame, GFSK, 4/8PSK, 16/64QAM modulation, seamless handovers and full mobility management capabilities with authentication and ciphering. The Average transmission power is 10 mW (250 mW peak, ontime is 417us/10000us thus 10.43mW average) in Europe and 4mW (100mW peak) in the US.
DECT may support the audio codecs according to G.726, G.711, G.722 (wideband), G.729.1 (wideband) and MPEG-4 ER LD AAC (wideband and super-wideband) and detailed audio specifications for narrowband (3.1kHz) and wideband (7kHz) telephony. The ETSI DECT specifications include a complete set of signalling and NWK procedures for PSTN/ISDN telephony, VoIP telephony (SIP or H.323), mixed scenarios (FP with PSTN and VoIP network connectivity), PABX environments, WLL (Wireless Local Loop) applications and CTM (Cordless Terminal Mobility) applications.
DECT Packet Radio Service (DPRS) provides packet data up to 840kbit/s (GFSK modulation) or up to 5Mbit/s (High Level Modulation) with support for multibearer, asymmetric connections, and efficient packet data handling, a Channel access time (from suspend state) of 15ms (first bearer), 2ms (additional bearers). DECT data is connection Oriented and Full Mobility Management Procedures (similar to a cellular system), has simplified modes for Wireless LAN operation, and low data rate applications, dual ARQ architecture with ARQ at MAC and at DLC layer, optional channel encoding (based on Turbo coding) for use with High Level Modulation modes and additional data profiles for circuit mode transmission and for ISDN emulation.

DECT 6.0 is a marketing term refering to US/Canadian 1.9GHz DECT phones. XDECTR is a Uniden technology for extending the DECT range.

Common Interface (CI) DECT standards published by ETSI (Europe):
EN 300 175-1: DECT Overview
EN 300 175-2: Physical Layer (PHL)
EN 300 175-3: Medium Access Control (MAC) layer
EN 300 175-4: Data Link Control (DLC) layer
EN 300 175-5: Network (NWK) layer
EN 300 175-6: Identities and addressing
EN 300 175-7: Security features
EN 300 175-8: Speech and audio coding and transmission
and the later drafted standards:
EN 300 444: Generic Access Profile (GAP)
EN 301 649: DECT Packet Radio Service (DPRS)

New Generation DECT standards (Europe):
TR 102 570: Overview and Requirements
TS 102 527-1: Wideband speech
TS 102 527-2: Support of transparent IP packet data
TS 102 527-3: Extended wideband speech services
TS 102 527-4: Light Data Services, SUOTA, downloading and HTTP applications
TS 102 841: Extended wideband speech services; Profile Test Specification (PTS) and Test Case Library (TCL)
and others:
EN 300 176-1: Test specification, Radio
EN 300 176-2: Test specification, Audio and Speech
TBR 6: General Terminal Attachment requirements (Radio Interface)
TBR 10: General Terminal Attachment requirements (Telecom/Audio Channel).
EN 301 437: Terminal Attachment requirements for pan-European PSTN approval
ATAAB notes (additional PSTN specifications, mostly outdated)

Regulatory Standards (Europe):
EN 301 406: RF
EN 301 489-6: EMI/EMC
EN 50371 / EN 62311: EMF, Health (note: older stanards not used anymore are ICNIRP Guideline i.c.m the ES 59005 test methods)
EN 60950-1: Safety
and possibly:
EN 301 908-10: EMC and RF spectrum Matters (ERM) for Base Stations (BS), Repeaters and User Equipment (UE) for IMT-2000 3th-Generation cellular networks (Harmonised Standard for IMT-2000, FDMA/TDMA (DECT) covering essential requirements of R&TTE article 3.2)

Miscellaneous articles about DECT published by Telconformity:

Major organizations working on/with DECT:

• DECT Forum
• DECT Web
• Home Gateway Initiative (HGI)
• CAT-iq
• UTAM (U.S.A)
• OSMOCOM (Open Source Implementation of a DECT stack)
• ECO-DECT
• Wiki DECT

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