Glossary in the Wireless World
you are a mobile phone user or an owner of a handheld device
or smart phone, you may encounter technical and industry-specific
terms like GSM, CDMA,
WAP, MMS, SMS,
GPRS (2.5G), 3G, Wi-Fi
and bluetooth. To have a better understanding
of the wireless world we're in, let us take a look at these
technologies in turn.
System for Mobile communication) is a digital
mobile telephone system that is widely used in Europe and
other parts of the world. GSM uses a variation of time division
multiple access (TDMA)
and is the most widely used of the three digital wireless
telephone technologies (TDMA, GSM, and CDMA).
GSM digitizes and compresses data, then sends it down a channel
with two other streams of user data, each in its own time
slot. It operates at either the 900 MHz or 1800 MHz frequency
GSM is the de facto wireless telephone standard in Europe.
GSM has over 120 million users worldwide and is available
in 120 countries, according to the GSM MoU Association. Since
many GSM network operators have roaming agreements with foreign
operators, users can often continue to use their mobile phones
when they travel to other countries.
American Personal Communications (APC), a subsidiary of Sprint,
is using GSM as the technology for a broadband
personal communications service (PCS).
The service will ultimately have more than 400 base stations
for the palm-sized handsets that are being made by Ericsson,
Motorola, and Nokia. The handsets include a phone, a text
pager, and an answering machine.
GSM together with other technologies is part of an evolution
of wireless mobile telecommunication that includes High-Speed
Circuit-Switched Data (HCSD), General Packet Radio System
(GPRS), Enhanced Data GSM Environment (EDGE),
and Universal Mobile Telecommunications Service (UMTS).
(Code-Division Multiple Access) refers to any of several protocols
used in so-called second-generation (2G) and third-generation
communications. As the term implies, CDMA is a form of multiplexing,
which allows numerous signals to occupy a single transmission
optimizing the use of available bandwidth.
The technology is used in ultra-high-frequency (UHF)
telephone systems in the 800-MHz and 1.9-GHz
CDMA employs analog-to-digital conversion (ADC)
in combination with spread
spectrum technology. Audio input is first digitized into
binary elements. The frequency of the transmitted signal is
then made to vary according to a defined pattern (code), so
it can be intercepted only by a receiver whose frequency response
is programmed with the same code, so it follows exactly along
with the transmitter frequency. There are trillions of possible
frequency-sequencing codes; this enhances privacy and makes
The CDMA channel is nominally 1.23 MHz wide. CDMA networks
use a scheme called soft
handoff, which minimizes signal breakup as a handset passes
from one cell to another. The combination of digital and spread-spectrum
modes supports several times as many signals per unit bandwidth
as analog modes. CDMA is compatible with other cellular technologies;
this allows for nationwide Roaming.
The original CDMA standard, also known as CDMA
One and still common in cellular telephones in the U.S.,
offers a transmission speed of only up to 14.4 Kbps
in its single channel form and up to 115 Kbps in an eight-channel
form. CDMA2000 and wideband
CDMA deliver data many times faster.
also known as IMT-CDMA Multi-Carrier or 1xRTT, is a code-division
multiple access (CDMA) version of the IMT-2000 standard developed
by the International Telecommunication Union (ITU). The CDMA2000
standard is third-generation (3-G) mobile wireless
can support mobile data communications at speeds ranging from
to 2 Mbps.
Versions have been developed by Ericsson and Qualcomm. As
of mid-2003, the CDMA Development Group reports that more
than 50 CDMA2000 networks have been deployed.
(Wideband Code-Division Multiple Access), an ITU standard
derived from Code-Division Multiple Access (CDMA), is officially
known as IMT-2000 direct spread. W-CDMA is a third-generation
(3G) mobile wireless technology that promises
much higher data speeds to mobile and portable wireless devices
than commonly offered in today's market.
W-CDMA can support mobile/portable voice, images, data, and
video communications at up to 2 Mbps
(local area access) or 384 Kbps
(wide area access). The input signals are digitized and transmitted
in coded, spread-spectrum mode over a broad range of frequencies.
A 5 MHz-wide carrier is used, compared with 200 kHz-wide
carrier for narrowband CDMA.
Application Protocol) is a specification for a set of communication
to standardize the way that wireless
devices, such as cellular telephones and radio transceivers,
can be used for Internet access, including e-mail, the World
Wide Web, newsgroups, and Internet Relay Chat (IRC).
While Internet access has been possible in the past, different
manufacturers have used different technologies. In the future,
devices and service systems that use WAP will be able to interoperate.
The WAP layers are:
Application Environment (WAE)
Session Layer (WSL)
Transport Layer Security (WTLS)
Transport Layer (WTP)
was conceived by four companies: Ericsson, Motorola, Nokia,
and Unwired Planet (now Phone.com). The Wireless Markup Language
is used to create pages that can be delivered using WAP.
There are other approaches to an industry standard besides
WAP, including i-Mode (please see below).
is the packet-based
service for mobile phones offered by Japan's leader in wireless
technology, NTT DoCoMo. Unlike most of the key players in
the wireless arena, i-Mode eschews the Wireless Application
Protocol (WAP) and uses a simplified version of HTML, Compact
Wireless Markup Language (CWML) instead of WAP's Wireless
Markup Language (WML).
NTT DoCoMo has said that eventually it will support WAP and
WML, but the company has not said exactly when this will happen.
First introduced in 1999, i-Mode was the world's first smart
phone for Web browsing. The i-Mode wireless data service offers
color and video over many phones. Its mobile computing service
enables users to do telephone banking, make airline reservations,
conduct stock transactions, send and receive e-mail, and have
access to the Internet. As of early 2000, i-Mode had an estimated
5.6 million users.
Messaging Service (MMS) - sometimes called Multimedia Messaging
System - is a communications technology developed by 3GPP
(Third Generation Partnership Project) that allows users to
exchange multimedia communications between capable mobile
phones and other devices. A successor to the Short Message
Service (SMS) protocol, MMS defines a way
to send and receive, almost instantaneously, wireless messages
that include images, audio, and video clips in addition to
text. When the technology has been fully developed, it will
support the transmission of streaming
video. A common current application of MMS messaging is
messaging (the use of camera phones to take photos for
immediate delivery to a mobile recipient). Other possibilities
include animations and graphic presentations of stock quotes,
sports news, and weather reports.
According to MobileStreams, MMS will be developed in two separate
phases. Based on General Packet Radio Services (GPRS),
the currently available MMS is similar to a brief PowerPoint
presentation. The second phase of MMS will require a 3G
network to enable streaming video. An intermediate technology,
Enhanced Messaging Service (EMS)
has more capabilities than SMS, but fewer than MMS. Unlike
MMS, EMS doesn't require upgrades to network infrastructures.
Unlike SMS and EMS, the size of an MMS message is unlimited,
although service providers are likely to impose their own
MMS-capable devices are available from a number of vendors,
including Ericsson, Motorola and Nokia.
Message Service (SMS) is a service for sending messages of
up to 160 characters (224 characters if using a 5-bit mode)
to mobile phones that use Global System for Mobile (GSM) communication.
GSM and SMS service is primarily available in Europe. SMS
is similar to paging. However, SMS messages do not
require the mobile phone to be active and within range and
will be held for a number of days until the phone is active
and within range. SMS messages are transmitted within the
or to anyone with roaming
service capability. They can also be sent to digital phones
from a Web site equipped with PC Link or from one digital
phone to another. Typical uses of SMS include:
a mobile phone owner of a voicemail message
a salesperson of an inquiry and contact to call
a doctor of a patient with an emergency problem
a service person of the time and place of their next call
a driver of the address of the next pickup
gateway is a Web site that lets you enter an SMS message to
someone within the cell served by that gateway or that acts
as an international gateway for users with roaming capability.
Packet Radio Services (GPRS) is often described as "2.5G"
- that is, a technology between the second generation (2G)
and third generation (3G) of mobile telephony. It is a packet-based
communication service that promises data rates from 56 up
to 114 Kbps
and continuous connection to the Internet for mobile phone
and computer users. The higher data rates will allow users
to take part in video conferences and interact with multimedia
Web sites and similar applications using mobile handheld
devices as well as notebook computers. GPRS is based on Global
System for Mobile (GSM) communication and
will complement existing services such as circuit-switched
cellular phone connections and the Short Message Service (SMS).
In theory, GPRS packet-based service should cost users less
than circuit-switched services since communication channels
are being used on a shared-use, as-packets-are-needed basis
rather than dedicated only to one user at a time. It should
also be easier to make applications available to mobile users
because the faster data rate means that middleware
currently needed to adapt applications to the slower speed
of wireless systems will no longer be needed. As GPRS becomes
available, mobile users of a virtual private network (VPN)
will be able to access the private network continuously rather
than through a dial-up connection.
GPRS will also complement Bluetooth, a standard for replacing
wired connections between devices with wireless radio connections.
In addition to the Internet Protocol (IP),
GPRS supports X.25,
a packet-based protocol that is used mainly in Europe. GPRS
is an evolutionary step toward Enhanced Data GSM Environment
and Universal Mobile Telephone Service (UMTS).
an abbreviation for third-generation wireless. The third generation,
as its name suggests, follows the first generation (1G) and
second generation (2G) in wireless communications. The 1G
period began in the late 1970s and lasted through the 1980s.
These systems featured the first true mobile phone systems,
known at first as "cellular mobile radio telephone."
These networks used analog
voice signaling, and were little more sophisticated than repeater
networks used by amateur
radio operators. The 2G phase began in the 1990s, and
much of this technology is still in use. The 2G cell phone
voice encoding. Examples include CDMA,
and GSM. Since its inception, 2G technology
has steadily improved, with increased bandwidth,
routing, and the introduction of multimedia.
3G include capabilities and features such as:
multimedia (voice, data, video, and remote control)
on all popular modes (cellular telephone, e-mail, paging,
fax, videoconferencing, and Web browsing)
bandwidth and high speed (upwards of 2 Mbps)
flexibility (repeater, satellite, LAN)
at approximately 2 GHz transmit and receive frequencies
capability throughout Europe, Japan, and North America
3G is generally considered applicable mainly to mobile wireless,
it is also relevant to fixed
wireless and portable wireless. The ultimate 3G system
might be operational from any location on, or over, the earth's
surface, including use in homes, businesses, government offices,
medical establishments, the military, personal and commercial
land vehicles, private and commercial watercraft and marine
craft, private and commercial aircraft (except where passenger
use restrictions apply), portable (pedestrians, hikers, cyclists,
campers), and space stations and spacecraft.
is a telecommunications industry specification that describes
how mobile phones, computers, and personal digital assistants
can be easily interconnected using a short-range wireless
connection. Using this technology, users of cellular phones,
pagers, and personal digital assistants can buy a three-in-one
phone that can double as a portable phone at home or in the
office, get quickly synchronized with information in a desktop
or notebook computer, initiate the sending or receiving of
a fax, initiate a print-out, and, in general, have all mobile
and fixed computer devices be totally coordinated.
requires that a low-cost transceiver chip be included in each
device. The transceiver transmits and receives in a previously
unused frequency band of 2.45 GHz that is available globally
(with some variation of bandwidth in different countries).
In addition to data, up to three voice channels are available.
Each device has a unique 48-bit address from the IEEE
802 standard. Connections can be point-to-point or multipoint.
The maximum range is 10 meters. Data can be exchanged at a
rate of 1 megabit
per second (up to 2 Mbps in the second generation of the technology).
A frequency hop scheme allows devices to communicate even
in areas with a great deal of electromagnetic interference.
Built-in encryption and verification is provided.
got its unusual name in honor of Harald Bluetooth, king of
Denmark in the mid-tenth century.
(short for "wireless fidelity") is a term for certain
types of wireless
local area network (WLAN)
that use specifications in the 802.11
family. The term Wi-Fi was created by an organization called
the Wi-Fi Alliance, which oversees tests that certify product
interoperability. A product that passes the alliance tests
is given the label "Wi-Fi certified" (a registered
Originally, Wi-Fi certification was applicable only to products
using the 802.11b
standard. Today, Wi-Fi can apply to products that use any
802.11 standard. The 802.11 specifications are part of an
evolving set of wireless network standards known as the 802.11
family. The particular specification under which a Wi-Fi network
operates is called the "flavor" of the network.
Wi-Fi has gained acceptance in many businesses, agencies,
schools, and homes as an alternative to a wired LAN. Many
airports, hotels, and fast-food facilities offer public access
to Wi-Fi networks. These locations are known as hot
spots. Many charge a daily or hourly rate for access,
but some are free. An interconnected area of hot spots and
points is known as a hot
Unless adequately protected, a Wi-Fi network can be susceptible
to access by unauthorized users who use the access as a free
Internet connection. The activity of locating and exploiting
security-exposed wireless LANs is called war
driving. An identifying iconography, called war
chalking, has evolved. Any entity that has a wireless
LAN should use security safeguards such as the Wired Equivalent
encryption standard, the more recent Wi-Fi Protected Access
Internet Protocol Security (IPsec),
or a virtual private network (VPN).