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Wednesday, October 19, 2011

Telecom


GSM
(Global System for Mobile Communications) A digital cellular phone technology based on TDMA that is the predominant system in Europe, but also used worldwide. Developed in the 1980s, GSM was first deployed in seven European countries in 1992. It operates in the 900MHz and 1.8GHz bands in Europe and the 1.9GHz PCS band in the U.S. Based on a circuit-switched system that divides each 200 kHz channel into eight 25 kHz time slots, GSM defines the entire cellular system, not just the TDMA air interface.

GPRS
General Packet Radio Service) An enhancement to the GSM mobile communications system that supports data packets. GPRS enables continuous flows of IP data packets over the system for such applications as Web browsing and file transfer. GPRS differs from GSM's short messaging service (GSM-SMS) which is limited to messages of 160 bytes in length. See GSM.

3G
(3rd Generation) The current generation of data transmission over a cellular network. In CDMA networks such as Verizon Wireless and Sprint, EV-DO is the 3G service. Cingular and other TDMA-based networks support the UMTS technology for 3G, and GPRS is the 3G data service for Vodaphone and other GSM carriers.

UMTS

(Universal Mobile Telecommunications System) The European implementation of the 3G wireless phone system. UMTS, which is part of IMT-2000, provides service in the 2GHz band and offers global roaming and personalized features. Designed as an evolutionary system for GSM network operators, multimedia data rates up to 2 Mbps are expected using WCDMA. In the interim, GPRS and EDGE are 2.5G technologies that speed up wireless data for GSM users.

DSP

(Digital Signal Processor) A special-purpose CPU used for digital signal processing applications (see definition #2 below). It provides ultra-fast instruction sequences, such as shift and add, and multiply and add, which are commonly used in math-intensive signal processing. DSP chips are widely used in a myriad of devices, including cellphones, sound cards, fax machines, modems, hard disks and digital TVs. The first DSP chip used in a commercial product was believed to be in the very popular Speak & Spell game

TDMA

(Time Division Multiple Access) A satellite and cellular phone technology that interleaves multiple digital signals onto a single high-speed channel. For cellular, TDMA triples the capacity of the original analog method (FDMA). It divides each channel into three subchannels providing service to three users instead of one. The GSM cellular system is also based on TDMA, but GSM defines the entire network, not just the air interface.

CDMA

(Code Division Multiple Access) A method for transmitting simultaneous signals over a shared portion of the spectrum. The foremost application of CDMA is the digital cellular phone technology from QUALCOMM that operates in the 800MHz band and 1.9GHz PCS band. CDMA phones are noted for their call quality.

WAP

Wireless Application Protocol) A standard for providing cellular phones, pagers and other handheld devices with secure access to e-mail and text-based Web pages. Introduced in 1997 by Phone.com (later Openwave Systems), Ericsson, Motorola and Nokia, WAP provides a complete environment for wireless applications that includes a wireless counterpart of TCP/IP and a framework for telephony integration such as call control and phone book access.

SS7

(Signaling System 7) The protocol used in the public switched telephone system (the "intelligent network" or "advanced intelligent network") for setting up calls and providing services. SS7  is a separate signaling network that is used in Class 4 and Class 5 voice switches.

VoIP

(Voice Over IP) A telephone service that uses the Internet as a global telephone network. Many companies, including Vonage, 8x8 and AT&T (CallVantage), typically offer calling within the country for a fixed fee and a low per-minute charge for international. Broadband Internet access (cable or DSL) is required, and regular house phones plug into an analog telephone adapter (ATA) provided by the company or purchased from a third party.

SIGTRAN

(SIGnaling TRANsport) An IP telephony protocol from the IETF that is used to transfer SS7 signals over IP networks. The telco switch sends SS7 signals to a signaling gateway (SG) that converts them into SIGTRAN packets, which travel over IP to the next signaling gateway or to a softswitch if the destination is not another PSTN. SIGTRAN uses the Stream Control Transmission Protocol (SCTP) for reliable transport. See IP telephony and SCTP.

MGCP/MEGACO

(Media Gateway Control Protocol/MEdia GAteway COntroller) An IP telephony signaling protocol from the IETF. MGCP was the original protocol, which evolved into MEGACO. Both protocols are designed for implementation in IP phones that are lower cost than SIP or H.323 phones. MGCP/MEGACO requires the use of softswitches for call control and more resembles the telephony model of the circuit-switched PSTN than do SIP and H.323. The softswitch is aware of the entire call throughout its duration (it manages state) and enables operator intervention like the PSTN. MCGP/MEGACO is a combination of the SGCP and IPCD protocols, and many devices that implement MGCP/MEGACO also support SIP and/or H.323.
SIP

(Session Initiation Protocol) An IP telephony signaling protocol developed by the IETF. Primarily used for voice over IP (VoIP) calls, SIP can also be used for video or any media type; for example, SIP has been used to set up multi-player Quake games. With SIMPLE extensions for IM and presence, SIP is also used for instant messaging

H.323

An ITU standard for realtime voice and videoconferencing over packet networks, including LANs, WANs and the Internet. Although H.323 is a very comprehensive standard that supports voice, video, data, application sharing and whiteboarding, the parts relating to audio protocols have been widely used for IP telephony applications.




TMN

(Telecommunications Management Network) A set of international standards for network management from the ITU. It is used by large carriers such as Sprint, MCI WorldCom and AT&T.

Bluetooth

A wireless personal area network (WPAN) technology from the Bluetooth Special Interest Group (www.bluetooth.com) founded in 1998 by Ericsson, IBM, Intel, Nokia and Toshiba. Bluetooth is an open standard for short-range transmission of digital voice and data that supports point-to-point and multipoint applications. Some of the first Bluetooth applications have been for cellphones, providing a wireless connection to a headset and to an automobile's audio system for hands-free operation

Jini

Pronounced "gee-nee." A Java-based distributed computing environment from Sun in which devices can be plugged into the network and automatically offer their services and make use of other services on the network. Jini creates a "network dialtone" allowing, for example, any PDA or laptop to be plugged in and immediately be able to use printers and other resources. It turns "peripherals into services," so that when a disk drive is plugged in, it becomes a storage service rather than just another disk drive

3 comments:

Amelia said...

Informative article. Thanks for listings all the telecom technologies and explaining them in short. I was aware of most of them but some are pretty new to me.
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Unknown said...

The article is quite detailed and informative.The author has provided a quick information on all the technologies being used in telecommunication.
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Unknown said...

Thanks for listings all the telecom technologies and explaining them in short. I was aware of most of them but some are pretty new to me.

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