glossary about wireless

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reference:
http://www.phonescoop.com/glossary/
2G
2nd-generation (2G) refers to the initial group of wireless technology standards that were digital instead of analog (1G).
Digital increased capacity significantly over analog, permitting many more people to use the same base station (tower) at one time.
2G offers both data and voice, but unlike 2.5G or 3G standards, transferring data over a 2G involves a "data call", which uses as much network capacity as any other call, and uses that capacity for the duration of the connection, regardless of whether data is being transmitted at any one moment.
Newer 2.5G and 3G standards are much faster for data, and only use network capacity when data is actively being transmitted.
3G
3G Stands for 3rd-generation. Analog cellular phones were the first generation. Digital phones marked the second generation (2G).
3G is loosely defined, but generally includes high data speeds, always-on data access, and greater voice capacity.
The high data speeds are possibly the most prominent feature, and certainly the most hyped. They enable such advanced features as live, streaming video.
There are several different 3G technology standards. The most prevalent worldwide is UMTS, which is based on WCDMA. (The terms WCDMA and UMTS are often used interchangeably.) UMTS is the 3G technology of choice for most carriers that used GSM as their 2G technology.
See:
WCDMA
The other major standard is cdma2000, which is an evolution of CDMA 2G technology. There are several types of cdma2000, each offering different data rates and levels of compatibility with 2G CDMA. EV-DO Rev A is the most common today.
See:
EV-DO

3GPP
3rd Generation Partnership Project
A technical standards group focusing on GSM, GPRS, EDGE, WCDMA, and related technologies.
3GPP2
3rd Generation Partnership Project 2
A technical standards group focusing on CDMA2000 and related technologies.

4G
Fourth Generation
A somewhat vague term used to describe wireless mobile radio technologies that offer faster data rates than current 3G (third generation) technologies.
4G networks are also more data-centric and based on standard Internet technologies such as IP. Voice service is typically provided using a special form of VoIP.
WiMAX and LTE are examples of 4G technologies.
See:
WiMAX
See:
LTE
802.11
802.11 is a set of technical specifications for networking and wireless communication, standardized by IEEE.
There are several variants of 802.11. The most common is 802.11b, also known as Wi-Fi, which provides speeds up to 11 mbs. 802.11g and 802.a are faster versions. Many 802.11g and 802.11a products are backward-compatible with the original 802.11b.

CDMA
Code-Division Multiple Access.
CDMA is a digital wireless technology. It is a general type of technology, implemented in many specific technologies. But the term "CDMA" is also commonly used to refer to one specific family of technologies (IS-95 and CDMA2000) that competes with technologies such as GSM.
CDMA is a "spread spectrum" technology, which means that it spreads the information contained in a particular signal of interest over a much greater bandwidth than the original signal.
Unlike many competing technologies, CDMA has no hard limit for the number of users who may share one base station (tower). Instead, with CDMA, additional users can connect until the base station determines that call quality would suffer beyond a set limit.
CDMA (IS-95) systems have been in commercial operation since 1995. CDMA networks operate in the 800 and 1900 MHz frequency bands with primary markets in the Americas and Asia. IS-95 CDMA systems are sometimes referred to as cdmaOne. The next evolutionary step for CDMA to 3G services is cdma2000.

CDMA2000
(1x)
cdma2000 is a third-generation (3G) wireless technology that is evolved from existing CDMA 2G technology. Its main features are faster data rates, always-on data service, and improved voice network capacity (more people can use each tower at the same time).
cdma2000 will be deployed in at least three phases.
The first, 1xRTT, supports up to 144 Kbps packet data speeds. It also doubles voice capacity over previous CDMA networks (IS-95).
The second release of 1x, 1xEV-DO, will support data rates up to 2.4 Mbps. It can only be deployed separately from voice networks - in its own spectrum - although devices can be made to access both networks.
The third, 1xEV-DV, supports circuit and packet data rates up to 3-5 Mbps. It fully integrates with 1xRTT voice networks.
A possible fourth phase is cdma2000 3x, although it uses three times as much spectrum.

EDGE
Enhanced Data for Global Evolution.
An upgrade for GSM/GPRS networks that triples data rates (speed) over standard GPRS.
See:
GPRS
EDGE is used automatically when both the phone and network support it. EDGE phones will automatically revert to the slower GPRS standard when EDGE service is not available.
Although many EDGE phones and devices are theoretically capable of up to 236 Kbps, most EDGE networks are only configured to allow up to 135 Kbps, to conserve spectrum resources. Real-world data rates are usually lower than the maximum.
Because it is based on existing GSM and GPRS technology, EDGE is a smooth upgrade for GSM network operators.
Although EDGE works at a low level within the GSM standard that includes voice, the main benefit is to increase GPRS data rates. GPRS operating over EDGE is called EGPRS.
Although EDGE is faster than GPRS, it is not as fast as 3G technologies such as HSDPA and EVDO.

EGSM
Extended GSM
A small radio frequency band used in Europe to provide added network capacity for GSM 900 networks.
EGSM spectrum is 880-890 MHz paired with 925-935 MHz, which is just below the original GSM 900 band.
Phones described as having "EGSM" or "EGSM 900" support both the orginal GSM 900 band and the extended band. Older phones with "GSM 900" may not support EGSM. Most newer phones with "GSM 900" do support EGSM, it is just not listed that way since it is assumed that newer phones support it.

GPRS
General Packet Radio Service.
A packet-switched technology that enables data communications.
GPRS is used for various data applications on phones, including wireless Internet (WAP), MMS, and software that connects to the Internet. Basically, any network connection that is not voice or text messaging uses a data connection like GPRS.
GPRS offers a tenfold increase in data speed over previous (circuit-switched) technologies, up to 115kbit/s (in theory). Typical real-world speeds are around 30-40 Kbps.
Newer technologies like EDGE and 3G are much faster.
See:
EDGE
Using a packet switching, subscribers are always connected and always on-line, so services will be easy and quick to access.
GPRS is considered a "2.5G" technology, meaning it is more advanced than standard 2G digital technology, but does not meet the requirements of a full-feldged 3G technology.

GSM
Global System for Mobile Communication.
GSM is the dominant 2G digital mobile phone standard for most of the world. It determines the way in which mobile phones communicate with the land-based network of towers.
GSM is one of two major mobile phone technologies in the U.S. The other is CDMA. Cingular and T-Mobile use GSM. Sprint and Verizon use CDMA. GSM is more prevalent in most other parts of the world, and especially in Europe.
Although GSM and CDMA provide similar basic features and services to end-users, (such as voice calling, text messaging, and data services,) they operate very differently at many technical levels. This makes GSM phones completely incompatible with CDMA networks, and vice-versa.
The most visible feature of GSM are SIM cards. SIM cards are removable, thumbnail-sized smart cards which identify the user on the network, and can also store information such as phone book entries. SIM cards allows users to switch phones by simply moving their SIM card from one phone to the other.
For information about GSM-related 2.5G and 3G technology:
See:
GPRS
See:
EDGE
See:
WCDMA

IMS
(IP Multimedia Subsystem)
IMS is a general-purpose, open industry standard for voice and multimedia communications over packet-based IP networks. It is a core network technology, that can serve as a low-level foundation for technologies like Voice over IP (VoIP), Push-To-Talk (PTT), Push-To-View, Video Calling, and Video Sharing. IMS is based primarily on SIP (session initiation protocol).
For users, IMS-based services enable person-to-person and person-to-content
communications in a variety of modes – including voice, text, pictures and
video, or any combination of these – in a highly personalized and controlled
way.
For carriers, benefits of IMS include increased flexibility for carriers to offer new 3G services, and lower costs.
The idea behind IMS is to eventually move all voice and multimedia communication (mobile and fixed) to flexible, packet-based technologies derived from Internet protocols. It is intended to eventually replace all circuit-based technologies currently used in mobile networks, although it can easily be phased in, in a piecemeal fashion, integrating with circuit-based technologies and existing billing systems, etc.

IMSI
International Mobile Subscriber Identity
The IMSI is a globally-unique code number that identifies a GSM subscriber to the network. The IMSI is linked to your account information with the carrier. The IMSI resides in the SIM card, which can be moved from one GSM phone to another

MMS
Multimedia Messaging Service
MMS is a descendant of SMS (Short Messaging Service). MMS extends text messaging to include longer text, graphics, photos, audio clips, video clips, or any combination of the above, within certain size limits.
MMS is frequently used to send photos and videos from camera phones to other MMS phones or email accounts. Most camera phones have MMS, but many non-camera phones have it as well.
Many newer MMS phones also support SMIL, which allows various parts of an MMS message to be arranged into a small multimedia "slideshow" to be viewed on another SMIL-capable MMS phone.
See:
SMIL
See:
SMS

OFDM
Orthogonal Frequency Division Multiplexing
OFDM is a technology used to compress a large amount of data into a small amount of bandwidth. This is done by dividing a large amount of data into smaller chunks, then sending that data simultaneously over a number of frequencies. The specific techniques OFDM uses allow a large amount of data to be transmitted quickly and reliably, with a minimum of loss or interference.
Using OFDM, a data channel is subdivided into the smallest size bands of frequency that can carry a small bit of information without overlapping or interfering with each other. Data is then split up and transmitted over all the sub-channels simultaneously. Because the data is split over so many channels, and because the channels are spaced exactly far enough apart so as not to interfere with each other, OFDM is more accurate, and thus more efficient, than current cellular data standards.
OFDM technology is used in certain variants of Wi-Fi (802.11a, 802.11n, MIMO), WiMax (802.16) and WiBro, ADSL, as well as number of digital broadcasting technologies such as DAB and DVB-T. OFDM promises to play an important part in any 4G (fourth generation) cellular standard as well.

PIN
Personal Identification Number.
In the context of wireless devices, the PIN is a like a password that prevents other people from using your service. It is numeric code used to unlock the phone and/or complete a call or data transmission. It must be entered each time you use the phone, unless you disable it.
(Note that this is different from the type of "unlocking" that will let you use your phone with a different carrier.)
In GSM phones, the PIN is generally associated with the SIM card, not the phone.
GSM SIM cards will lock up if an incorrect PIN is entered three times in a row. If this happens, a different, longer code called a PUK code is required to unlock the phone.
See:
PUK code

SIM


Subscriber Identity Module.
A small, stamp-size "smart card" used in a GSM or iDEN phone.
The SIM card contains a microchip that stores data that identifies the user to the carrier. The data is also used to encrypt voice and data transmissions, making it nearly impossible to listen in on calls.
The SIM can also store phone book information - phone numbers and associated names.
The SIM, typically located under the battery, can easily be removed and placed in another phone. This will cause the new phone to instantly operate using the subscriber's existing phone number and account.
All GSM phones and most iDEN phones use SIM cards. CDMA, TDMA, and AMPS (analog) phones generally do not use SIM cards. The information is instead programmed directly into the phone. However, some CDMA phones for China and Latin America use a very similar type of card called R-UIM.
See:
R-UIM
WCDMA / UMTS (3G) phones use an upgraded version of SIM cards called USIM cards:
See:
USIM

SMS
(Short Message Service)
SMS is a feature available with practically all modern mobile phones that allow users to send and receive short text messages.
Basic SMS messages are addressed directly to a mobile phone number. Most U.S. carriers now allow sending to mobile phone numbers of other carriers. Most phones and carriers also support sending SMS from a phone directly to an email address.
Newer variants of SMS include Long (Concatenated) SMS, and EMS.
See:
Text Messaging


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