Wireless is a term used to describe telecommunications in which electromagnetic waves (rather than some form of wire) carry the signal over part or the entire communication path.

1. CHAPTER #1
OVERVIEW AND EVOLUTION OF
WIRELESS COMMUNICATION
WIRELESS AND MOBILE COMMUNICATION

2. Concept of Wireless Communication
 Wireless is a term used to describe telecommunications
in which electromagnetic waves (rather than some form
of wire) carry the signal over part or the entire
communication path.

3. WIRELESS EQUIPMENT
COMMON EXAMPLES OF WIRELESS EQUIPMENT
IN USE TODAY INCLUDE:
 Cellular Phones : these provide connectivity for portable and mobile
applications, both personal and business
 Global Positioning System (GPS): Allows drivers of cars and trucks,
captains of boats and ships, and pilots of aircraft to ascertain their location
anywhere on earth.
 Satellite television: Allows viewers in almost any location to select
from hundreds of channels.
 Wireless LANs or Local Area Networks: Provide flexibility and
reliability for business computer users.

4. Examples of Wireless Communication and Control
More specialised and exotic examples of wireless communications
and control include:
 Global System For Mobile Communication (GSM): A digital
mobile telephone system
 General Packet Radio Service (GPRS): A packet-based
wireless communication service that provides continuous
connection to the internet for mobile phone and computer users.
 Enhanced Data GSM Environment (EDGE): A faster version
of the global system for mobile (GSM) wireless service.

5. Examples of Wireless Communication and Control
 Universal mobile telecommunications system (UMTS): A
broadband, packet-based system donation a consistent set of
services to mobile computer and phone users no matter where
they are located in the world.
 Wireless application protocol (WAP): A set of communication
protocols to standard the way that wireless devices, such as
cellular telephones and radio transceivers, can be used for
internet access.
 I-mode: the world’s first “smart phone” for web browsing, first
introduced in japan; provides colour and video over telephone
sets.

6. Classification of Wireless
 Wireless can be divided into the following classes:
 Fixed wireless: The operation of wireless devices or systems in
homes and offices, and in particular, equipment connected to the
Internet via specialised modems
 Mobile wireless: The use of wireless devices or systems aboard
motorised, moving vehicles; examples include the automotive
cell phone and PCS (personal communications services)

7. Applications of Wireless Technology
 Television remote control: Modern televisions use wireless
(generally infrared) remote control units but now radio waves are
also used.
 Cellular telephony (phones and modems): These instruments
use radio waves to enable the operator to make phone calls from
many locations world-wide. They can be used anywhere there is
a cellular telephone site to house the equipment that is required to
transmit and receive the signal that is used to transfer both voice
and data to and from these instruments.

8. Applications of Wireless Technology
 WiFi: Wi-Fi (for wireless fidelity) is a wireless LAN technology
that enables laptop PC’s, PDA’s, and other devices to connect
easily to the internet. Wi-Fi is less expensive and nearing the
speeds of standard Ethernet and other common wire-based LAN
technologies.
 Wireless energy transfer: Wireless energy transfer is a process
where by electrical energy is transmitted from a power source to
an electrical load that does not have a built-in power source,
without the use of interconnecting wires.

9. Mobile Radio Communication
 Radio is the technology and practice that enables the transmission
and reception of information carried by long-wave
electromagnetic radiation.
 Radio makes it possible to establish wireless two-way
communication between individual pairs of transmitter and
receiver, and it is used for one-way broadcasts to many receivers.
 Radio signals can carry speech, music, telemetry, or digitally-
encoded entertainment.

10. Mobile Radio Communication
 Radio is used by the general public, within legal guidelines, or it
is used by private business or governmental agencies.
 Cordless telephones are possible because they use low-power
radio transmitters to connect without wires.
 Cellular telephones use a network of computer-controlled low
power radio transmitters to enable users to place telephone calls
away from phone lines.

11. Mobile Radio Transmission Systems
⚫SIMPLEX
 Communication in one direction (e.g. broadcast radio,
TV, paging systems).
 uses one channel
⚫HALF DUPLEX
 Communication in both direction but not at the same
time (e.g. wakie-talkies or Citizen’Band (CB)-radio).
 uses one channel
⚫FULLDUPLEX
 Simultaneous two-way communication (e.g. telephone
or cellular radio).
 uses two channels.

13. Duplex Techniques
 Methods for separating channels of different
directions
 Divide forward (downlink) and reverse (uplink)
communication “channels” on the same physical medium
Two methods:
 FDD: Frequency-Division Duplex.
 TDD: Time-Division Duplex.

14. Frequency Division Duplexing (FDD):
 FDD supports two-way radio communication by using two
distinct radio channels.
 One frequency channel is transmitted downstream
from the BS to the MS (forward channel).
 A second frequency is used in the upstream direction and
supports transmission from the MS to the BS (reverse
channel).
 Because of the pairing of frequencies, simultaneous
transmission in both directions is possible. To lessen self-
interference between upstream and downstream
transmissions, a minimum amount of frequency separation
must be maintained between the frequency pair.

15. Time Division Duplexing (TDD)
 TDD uses a single frequency band to transmit
signals in both the downstream and upstream
directions.
 TDD operates by toggling transmission
directions over a time interval.

16. FDD vs TDD
Figure 1.4: (a) Frequency division Duplexing and (b) time division
Duplexing

17. FDD vs TDD
 FDD can be used in both analog and digital system, but TDD
can only be used in digital system.
 FDD is more efficient for symmetric traffics, while TDD is
good for asynchronous traffics (data rates of two directions are
different).
 FDD needs a duplexer hardware but TDD does not.
 FDD is easier for radio planning since no interference
among base stations. But TDD require complex synchronization
among base stations.
 TDD has been used for indoor or small area wireless
applications.

18. Types of Wireless Communications…
 Mobile
 Cellular Phone
 WiMax (IEEE 802.16e)
 Portable
 Cordless Phones
 Wi-Fi/ WLAN (IEEE 802.11b/g/n)
 Bluetooth, UWB (IEEE 802.15.3), NFC
 Fixed
 U-NII Band (IEEE 802.11a)
 WiMax (IEEE 802.16d)
 Microwave Point-to-Point
 Satellite

19. Types of Wireless Transmission..(1)
 Radio Transmission
 Easily generated, omni-directionally travel long distance,
• easily penetrate buildings
 Problems
 Frequency-dependent
 Relative low bandwidth for data communication
 Tightly licensed by the government
 Microwave Transmission
 Widely used for long distance communication
 Gives a high S/N ratio, relatively inexpensive
 Problems
 Don’t pass throuth buildings well
 Weather and frequency-dependent

20.  Infrared and MillimeterWaves
1. Usually used for short-range communication
 Unable to pass through solid objects
 Used for indoor wireless LANs, not for outdoors
 Ligthwave Transmission
 Unguided optical signal, such as laser
 Connect two LANs in two building via laser attached
on their roof
 Unidirectional, easy to install, don’t require license
Types of Wireless Transmission..(2)

21. Differences between Wired and Wireless
The main difference between wired and wireless data
communication infrastructure is the existence of physical cabling.
A wired network uses wires (cables) to connect devices whereas a
wireless network uses radio waves.
Wired networks are easy to set up and troubleshoot whereas wireless
networks are comparatively difficult to set up, maintain and troubleshoot.
Wired network proves expensive when covering a large area because of
the wiring and cabling while wireless network do not involve this cost.
Wired networks have better transmission speeds than wireless ones.