A wireless network is a computer network that uses wireless data
connections between network nodes.
Wireless networking is a method by which homes, telecommunications
networks and business installations avoid the costly process of
introducing cables into a building, or as a connection between various
Wireless telecommunications networks are
generally implemented and administered using radio communication. This
implementation takes place at the physical level (layer) of the OSI
model network structure.
Examples of wireless networks include cell phone networks, wireless
local area networks (WLANs), wireless sensor networks, satellite
communication networks, and terrestrial microwave networks.
3 Types of wireless networks
Wireless ad hoc network
3.6 Cellular network
3.7 Global area network
3.8 Space network
4 Different uses
Wireless Network Elements
5.6.2 Absorption and reflection
5.6.3 Multipath fading
5.6.4 Hidden node problem
5.6.5 Shared resource problem
7 See also
9 Further reading
10 External links
The first professional wireless network was developed under the brand
ALOHAnet in 1969 at the University of Hawaii and became operational in
June 1971. The first commercial wireless network was the WaveLAN
product family, developed by NCR in 1986.
1991 2G cell phone network
802.11 "WiFi" protocol first release
1999 803.11 VoIP integration
Computers are very often connected to networks using wireless links,
Terrestrial microwave – Terrestrial microwave communication uses
Earth-based transmitters and receivers resembling satellite dishes.
Terrestrial microwaves are in the low gigahertz range, which limits
all communications to line-of-sight. Relay stations are spaced
approximately 48 km (30 mi) apart.
Communications satellites – Satellites communicate via microwave
radio waves, which are not deflected by the Earth's atmosphere. The
satellites are stationed in space, typically in geosynchronous orbit
35,400 km (22,000 mi) above the equator. These
Earth-orbiting systems are capable of receiving and relaying voice,
data, and TV signals.
Cellular and PCS systems use several radio communications
technologies. The systems divide the region covered into multiple
geographic areas. Each area has a low-power transmitter or radio relay
antenna device to relay calls from one area to the next area.
Radio and spread spectrum technologies –
Wireless local area
networks use a high-frequency radio technology similar to digital
cellular and a low-frequency radio technology.
Wireless LANs use
spread spectrum technology to enable communication between multiple
devices in a limited area. IEEE
802.11 defines a common flavor of
open-standards wireless radio-wave technology known as .
Free-space optical communication
Free-space optical communication uses visible or invisible light for
communications. In most cases, line-of-sight propagation is used,
which limits the physical positioning of communicating devices.
Types of wireless networks
Wireless personal area networks (WPANs) internet devices within a
relatively small area, that is generally within a person's reach.
For example, both
Bluetooth radio and invisible infrared light
provides a WPAN for interconnecting a headset to a laptop.
supports WPAN applications.
Wi-Fi PANs are becoming commonplace
(2010) as equipment designers start to integrate
Wi-Fi into a variety
of consumer electronic devices.
Intel "My WiFi" and
Windows 7 "virtual
Wi-Fi" capabilities have made
Wi-Fi PANs simpler and easier to set up
Wireless LANs are often used for connecting to local resources and to
A wireless local area network (WLAN) links two or more devices over a
short distance using a wireless distribution method, usually providing
a connection through an access point for internet access. The use of
OFDM technologies may allow users to move around
within a local coverage area, and still remain connected to the
Products using the IEEE
802.11 WLAN standards are marketed under the
Wi-Fi brand name.
Fixed wireless technology implements point-to-point
links between computers or networks at two distant locations, often
using dedicated microwave or modulated laser light beams over line of
sight paths. It is often used in cities to connect networks in two or
more buildings without installing a wired link.
Wireless ad hoc network
A wireless ad hoc network, also known as a wireless mesh network or
mobile ad hoc network (MANET), is a wireless network made up of radio
nodes organized in a mesh topology. Each node forwards messages on
behalf of the other nodes and each node performs routing. Ad hoc
networks can "self-heal", automatically re-routing around a node that
has lost power. Various network layer protocols are needed to realize
ad hoc mobile networks, such as Distance Sequenced Distance Vector
routing, Associativity-Based Routing, Ad hoc on-demand Distance Vector
routing, and Dynamic source routing.
Wireless metropolitan area networks are a type of wireless network
that connects several wireless LANs.
WiMAX is a type of
Wireless MAN and is described by the IEEE 802.16
Wireless wide area networks are wireless networks that typically cover
large areas, such as between neighbouring towns and cities, or city
and suburb. These networks can be used to connect branch offices of
business or as a public
Internet access system. The wireless
connections between access points are usually point to point microwave
links using parabolic dishes on the 2.4 GHz band, rather than
omnidirectional antennas used with smaller networks. A typical system
contains base station gateways, access points and wireless bridging
relays. Other configurations are mesh systems where each access point
acts as a relay also. When combined with renewable energy systems such
as photovoltaic solar panels or wind systems they can be stand alone
Main article: cellular network
Example of frequency reuse factor or pattern 1/4
A cellular network or mobile network is a radio network distributed
over land areas called cells, each served by at least one
fixed-location transceiver, known as a cell site or base station. In a
cellular network, each cell characteristically uses a different set of
radio frequencies from all their immediate neighbouring cells to avoid
When joined together these cells provide radio coverage over a wide
geographic area. This enables a large number of portable transceivers
(e.g., mobile phones, pagers, etc.) to communicate with each other and
with fixed transceivers and telephones anywhere in the network, via
base stations, even if some of the transceivers are moving through
more than one cell during transmission.
Although originally intended for cell phones, with the development of
smartphones, cellular telephone networks routinely carry data in
addition to telephone conversations:
Global System for Mobile Communications
Global System for Mobile Communications (GSM): The GSM network is
divided into three major systems: the switching system, the base
station system, and the operation and support system. The cell phone
connects to the base system station which then connects to the
operation and support station; it then connects to the switching
station where the call is transferred to where it needs to go. GSM is
the most common standard and is used for a majority of cell phones.
Personal Communications Service (PCS): PCS is a radio band that can be
used by mobile phones in North America and South Asia. Sprint happened
to be the first service to set up a PCS.
D-AMPS: Digital Advanced Mobile Phone Service, an upgraded version of
AMPS, is being phased out due to advancement in technology. The newer
GSM networks are replacing the older system.
Global area network
A global area network (GAN) is a network used for supporting mobile
across an arbitrary number of wireless LANs, satellite coverage areas,
etc. The key challenge in mobile communications is handing off user
communications from one local coverage area to the next. In IEEE
Project 802, this involves a succession of terrestrial wireless
Space networks are networks used for communication between spacecraft,
usually in the vicinity of the Earth. The example of this is NASA's
Some examples of usage include cellular phones which are part of
everyday wireless networks, allowing easy personal communications.
Another example, Intercontinental network systems, use radio
satellites to communicate across the world. Emergency services such as
the police utilize wireless networks to communicate effectively as
well. Individuals and businesses use wireless networks to send and
share data rapidly, whether it be in a small office building or across
In a general sense, wireless networks offer a vast variety of uses by
both business and home users.
"Now, the industry accepts a handful of different wireless
technologies. Each wireless technology is defined by a standard that
describes unique functions at both the Physical and the Data Link
layers of the OSI model. These standards differ in their specified
signaling methods, geographic ranges, and frequency usages, among
other things. Such differences can make certain technologies better
suited to home networks and others better suited to network larger
Each standard varies in geographical range, thus making one standard
more ideal than the next depending on what it is one is trying to
accomplish with a wireless network. The performance of wireless
networks satisfies a variety of applications such as voice and video.
The use of this technology also gives room for expansions, such as
from 2G to 3G and, most recently, 4G technology, which stands for the
fourth generation of cell phone mobile communications standards. As
wireless networking has become commonplace, sophistication increases
through configuration of network hardware and software, and greater
capacity to send and receive larger amounts of data, faster, is
Space is another characteristic of wireless networking. Wireless
networks offer many advantages when it comes to difficult-to-wire
areas trying to communicate such as across a street or river, a
warehouse on the other side of the premises or buildings that are
physically separated but operate as one.
Wireless networks allow
for users to designate a certain space which the network will be able
to communicate with other devices through that network.
Space is also created in homes as a result of eliminating clutters of
wiring. This technology allows for an alternative to installing
physical network mediums such as TPs, coaxes, or fiber-optics, which
can also be expensive.
For homeowners, wireless technology is an effective option compared to
Ethernet for sharing printers, scanners, and high-speed Internet
connections. WLANs help save the cost of installation of cable
mediums, save time from physical installation, and also creates
mobility for devices connected to the network.
are simple and require as few as one single wireless access point
connected directly to the
Internet via a router.
Wireless Network Elements
The telecommunications network at the physical layer also consists of
many interconnected wireline network elements (NEs). These NEs can be
stand-alone systems or products that are either supplied by a single
manufacturer or are assembled by the service provider (user) or system
integrator with parts from several different manufacturers.
Wireless NEs are the products and devices used by a wireless carrier
to provide support for the backhaul network as well as a mobile
switching center (MSC).
Reliable wireless service depends on the network elements at the
physical layer to be protected against all operational environments
and applications (see GR-3171, Generic Requirements for Network
Elements Used in
Wireless Networks – Physical Layer Criteria).
What are especially important are the NEs that are located on the cell
tower to the base station (BS) cabinet. The attachment hardware and
the positioning of the antenna and associated closures and cables are
required to have adequate strength, robustness, corrosion resistance,
and resistance against wind, storms, icing, and other weather
conditions. Requirements for individual components, such as hardware,
cables, connectors, and closures, shall take into consideration the
structure to which they are attached.
Compared to wired systems, wireless networks are frequently subject to
electromagnetic interference. This can be caused by other networks or
other types of equipment that generate radio waves that are within, or
close, to the radio bands used for communication. Interference can
degrade the signal or cause the system to fail.
Absorption and reflection
Some materials cause absorption of electromagnetic waves, preventing
it from reaching the receiver, in other cases, particularly with
metallic or conductive materials reflection occurs. This can cause
dead zones where no reception is available. Aluminium foiled thermal
isolation in modern homes can easily reduce indoor mobile signals by
10 dB frequently leading to complaints about the bad reception of
long-distance rural cell signals.
In multipath fading two or more different routes taken by the signal,
due to reflections, can cause the signal to cancel out at certain
locations, and to be stronger in other places (upfade).
Hidden node problem
The hidden node problem occurs in some types of network when a node is
visible from a wireless access point (AP), but not from other nodes
communicating with that AP. This leads to difficulties in media access
Shared resource problem
The wireless spectrum is a limited resource and shared by all nodes in
the range of its transmitters.
Bandwidth allocation becomes complex
with multiple participating users. Often users are not aware that
advertised numbers (e.g., for IEEE
802.11 equipment or LTE networks)
are not their capacity, but shared with all other users and thus the
individual user rate is far lower. With increasing demand, the
capacity crunch is more and more likely to happen. User-in-the-loop
(UIL) may be an alternative solution to ever upgrading to newer
technologies for over-provisioning.
Main article: Channel capacity in wireless communications
Understanding of SISO, SIMO, MISO and MIMO. Using multiple antennas
and transmitting in different frequency channels can reduce fading,
and can greatly increase the system capacity.
Shannon's theorem can describe the maximum data rate of any single
wireless link, which relates to the bandwidth in hertz and to the
noise on the channel.
One can greatly increase channel capacity by using MIMO
techniques, where multiple aerials or multiple frequencies
can exploit multiple paths to the receiver to achieve much higher
throughput – by a factor of the product of the frequency and aerial
diversity at each end.
Under Linux, the Central Regulatory Domain Agent (CRDA) controls the
setting of channels.
This section needs expansion. You can help by adding to it. (April
The total network bandwidth depends on how dispersive the medium is
(more dispersive medium generally has better total bandwidth because
it minimises interference), how many frequencies are available, how
noisy those frequencies are, how many aerials are used and whether a
directional antenna is in use, whether nodes employ power control and
so on. there are two bands for now 2.4 GHz and 5 GHz. mostly 5
gigahertz band gives better connection and speed.
Cellular wireless networks generally have good capacity, due to their
use of directional aerials, and their ability to reuse radio channels
in non-adjacent cells. Additionally, cells can be made very small
using low power transmitters this is used in cities to give network
capacity that scales linearly with population density.
Wireless electronic devices and health
Wireless access points are also often close to humans, but the drop
off in power over distance is fast, following the inverse-square
law. The position of the United Kingdom's Health Protection Agency
(HPA) is that “...radio frequency (RF) exposures from
likely to be lower than those from mobile phones.” It also saw
“...no reason why schools and others should not use WiFi
equipment.” In October 2007, the HPA launched a new
“systematic” study into the effects of
WiFi networks on behalf of
the UK government, in order to calm fears that had appeared in the
media in a recent period up to that time". Dr Michael Clark, of
the HPA, says published research on mobile phones and masts does not
add up to an indictment of WiFi.
Exposed terminal problem
Wireless access point
Wireless community network
Wireless LAN client comparison
Wireless site survey
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Wireless at Curlie (based on DMOZ)
Cable protection system
Prepay mobile phone
The Telephone Cases
Timeline of communication technology
Undersea telegraph line
Edwin Howard Armstrong
John Logie Baird
Alexander Graham Bell
Jagadish Chandra Bose
Lee de Forest
Erna Schneider Hoover
Charles K. Kao
Alexander Stepanovich Popov
Johann Philipp Reis
Vladimir K. Zworykin
Free-space optical communication
Network switching (circuit
Public Switched Telephone
World Wide Web