What is Wireless Communication?

Wireless communication is any form of communication that

doesn’t require the transmitter and reciever to have physical
contacts
• works under electromagnetic waves which available in space
and not vissible
• It involves the process of sending/receiving information through
invisible waves in the air
• do not use a waveguide to guide along the electromagnetic
signal from the sender to the receiver.
• The fundamental difference between wired and wireless
technologies resides in the physical channel.
 TRANSMISSION MEDIA
• In a data transmission system,
• The transmission medium is the physical path between transmitter and
receiver.

• guided media,
• electromagnetic waves are guided along a solid medium, such as
copper twisted pair, copper coaxial cable, and optical fiber.

• unguided media,
• wireless transmission occurs through the atmosphere, outer space, or
water.
 TRANSMISSION MEDIA

• The characteristics and quality of a data transmission are

determined both by
• the characteristics of the medium and
• the characteristics of the signal.
• In the case of guided media,
• the medium itself is more important in determining the
limitations of transmission.

• For unguided media,

• the bandwidth of the signal produced by the transmitting antenna is more
important than the medium in determining transmission characteristics.
 Cont…
• Electrical energy/signal should be converted to digital signal in
order to pass through wave/electromagnetic wave.

• A process of putting this digital data on to wave is called

modulation
a.Amplitude Modulation -send data with certain amplitude
b.Frequency Modulation -vary frequency techniques
Introduction to Wireless Communications & Mobile Computing

• A communication device can exhibit any one of the following characteristics:

• Fixed and wired: This configuration describes the typical desktop computer in
an office.
• The devices use fixed networks for performance reasons.
• Mobile and wired: carry the laptop from one hotel to the next, reconnecting
to the network via the telephone network and a modem.
Introduction to Wireless Communications & Mobile Computing

• A communication device can exhibit any one of the following characteristics:

• Fixed and wireless:
• A network
• installed in historical buildings to avoid damage by installing wires, or

• Installed at trade shows to ensure fast network setup.

• Mobile and wireless: No cable restricts the user, who can roam between different
wireless networks.

• Where Mobile Computing lays at?

Introduction to Wireless Communications & Mobile Computing
• Wireless Systems:
• television transmission broadcast by wireless radio transmitters - increasingly
being replaced by cable transmission.
• The point-to-point microwave circuits that formed the backbone of the
telephone network - are being replaced by optical fiber.
• wireless (cellular) technology is partially replacing the use of the wired
telephone network.
Introduction to Wireless Communications & Mobile Computing
• wireless systems:
• AM radio, FM radio, TV and paging systems.

• wireless LANs (WLAN).

• These are designed for much higher data rates than cellular systems, but
otherwise are similar to a single cell of a cellular system.
• ad hoc network.

• Self organized Network with no Infrastructure

• The network organizes itself into links between various pairs of nodes and
develops routing tables using these links.
 challenges of wireless communication
• The phenomenon of fading:
• The time variation of the channel strengths due to

• Small-scale fading
• due to the constructive and destructive interference of the multiple signal paths between
the transmitter and receiver.

• multipath fading

• Large-scale fading,
• due to path loss of signal as a function of distance and shadowing by large objects such
as buildings and hills.
Introduction to Wireless Communications & Mobile Computing
• Significant interference between transmitter–receiver pair
• The interference can be between
• transmitters communicating with a common receiver (uplink of a cellular system),

• signals from a single transmitter to multiple receivers (downlink of a

cellular system), or
• between different transmitter–receiver pairs (e.g., interference between
users in different cells).
Advantage of Wireless Communication
• Mobility-used every where you want (“anywhere,
anytime.”)
• Ease of infrastructure and setup
• Solution in area where cable is impossible to
install.
• Save times.
• Easier to maintain
etc….
Disadvantage
o Less secure-security vulnerability
o Distance limit
o Physical Barriers
o High cost for setting the infrastructure
o etc…
History
 Marconi invented wireless telegraph in 1896.
Marconi sent telegraphic signals across the Atlantic Ocean from
Cornwall to St. John's New found land; a distance of about 3200 km.
His invention allowed sending alphanumeric characters encoded in
an analog signal.
Unidirectional information transmission
This led to a great many developments in wireless communication
networks that support radio, television, mobile telephone, and
satellite communication systems
By the late 1930s, the need for bidirectional mobile communications
emerged.
Military ,police departments ,fire station….
 Cont…
• Many sophisticated military radio systems were developed during
and after WW2
• Great deal of attention has been focused on satellite
communications, wireless networking, and cellular technology.
• 1946, the first mobile telephone system
• Has a total of six speech channels for the whole city, the system
soon met its limits.
• Led to investigations of how the number of users could be increased.
• Researchers at AT&T’s and Bell Labs found the answer:
• the cellular principle, where the geographical area is divided into
cells; different cells might use the same frequencies.
• This principle forms the basis for the majority of wireless
communications
 Cont…
In 1957-60, the Soviet Union-(USSR) launched the first satellite
(Sputnik) and the U.S.A. soon followed.
The cellular or mobile telephone is the modern equivalent of
Marconi's wireless telegraph, offering two-party, two-way
communication.
The first-generation wireless phones used analog technology.
Abr:USSR-union soviet socialist republic–federal socialist in Eurasia
The current generation of wireless devices is built using digital
technology.
Digital networks carry much more traffic and provide better
reception and security than analog networks.
 Cont…
1980s, the phones were “portable,” but definitely not handheld.
In most languages, they were just called “carphones,”.
But at the end of the 1980s, handheld phones with good speech
quality and quite acceptable battery lifetime flourish.
The quality had become so good that in some markets digital
phones had difficulty establishing themselves.
Thank You!!