Chapter 1: Introduction
Introduction to wireless communication
Wireless communications is the transmission of voice and data without cable or wires. In place
of a physical connection, data travels through electromagnetic signals broadcast from sending
facilities to intermediate and end-user devices.
The first wireless transmitters went on the air in the early 20th century using radiotelegraphy,
which is radio communication using Morse code or other coded signals. Later,
as modulation made it possible to transmit voice and music wirelessly, the medium became
known as radio. Wireless transmitters use electromagnetic waves to carry voice, data, video or
signals over a communication path.
Generally, in a communication system, information is transmitted from transmitter to receiver
that are placed over a limited distance. With the help of Wireless Communication, the transmitter
and receiver can be placed anywhere between few meters (like a T.V. Remote Control) to few
thousand kilometers (Satellite Communication).
Communication Systems can be Wired or Wireless and the medium used for communication can
be Guided or Unguided. In Wired Communication, the medium is a physical path like Co-axial
Cables, Twisted Pair Cables and Optical Fiber Links etc. which guides the signal to propagate
from one point to other.
1
Such type of medium is called Guided Medium. On the other hand, Wireless Communication
doesn’t require any physical medium but propagates the signal through space. Since, space only
allows for signal transmission without any guidance, the medium used in Wireless
Communication is called Unguided Medium.
How does wireless communication work?
Have you ever wondered how your text message has reached your friend? You wake up with a
Good Morning image on your whats app. How did it find you? It’s magical to watch a tiny to a
large form of communication being transferred in a span of a few seconds without any physical
effort. As the name Electromagnetic suggests, it is the synergy between the electric and magnetic
fields.
The wireless communication network works based on these electromagnetic signals, which are
broadcasted through a device. The sending device must have the potential to propagate wireless
signals and the receiving device should be capable of capturing the sent signals. Only then does
the wireless communication system get created between the receiver and sender. The
communication network has various forms and methods- Mobile, Bluetooth, Broadcast radio,
Wi-Fi, Infrared communication and more. All these wireless network examples work differently,
but the common factor remains, i.e. without any wired connection.
2
We live in a World of communication and Wireless Communication, in particular, is a key part
of our lives. Some of the commonly used Wireless Communication Systems in our day – to –
day life are: Mobile Phones, GPS Receivers, Remote Controls, Bluetooth Audio and Wi-Fi etc.
How it transmit signal?
If there is no physical medium, then how does wireless communication transmit signals? Even
though there are no cables used in wireless communication, the transmission and reception of
signals is accomplished with Antennas.
3
Antennas are electrical devices that transform the electrical signals to radio signals in the form of
Electromagnetic (EM) Waves and vice versa. These Electromagnetic Waves propagates through
space. Hence, both transmitter and receiver consists of an antenna.
What is Electromagnetic Wave?
Electromagnetic Waves carry the electromagnetic energy of electromagnetic field through space.
Electromagnetic Waves include Gamma Rays (γ – Rays), X – Rays, Ultraviolet Rays, Visible
Light, Infrared Rays, Microwave Rays and Radio Waves. Electromagnetic Waves (usually Radio
Waves) are used in wireless communication to carry the signals.
An Electromagnetic Wave consists of both electric and magnetic fields in the form of time
varying sinusoidal waves. Both these fields are oscillating perpendicular to each other and the
direction of propagation of the Electromagnetic Wave is again perpendicular to both these fields.
Why Wireless Communication?
When wired communication can do most of the tasks that a wireless communication can, why do
we need Wireless Communication? The primary and important benefit of wireless
communication is mobility.
Apart from mobility, wireless communication also offers flexibility and ease of use, which
makes it increasingly popular day – by – day. Wireless Communication like mobile telephony
can be made anywhere and anytime with a considerably high throughput performance.
Another important point is infrastructure. The setup and installation of infrastructure for wired
communication systems is an expensive and time consuming job. The infrastructure for wireless
communication can be installed easily and low cost.
In emergency situations and remote locations, where the setup of wired communication is
difficult, wireless communication is a viable option.
4
Types of Services
1. Infrared Communication
Did you know that infrared (IR) communication is present in your home too? It is involved in
short-range communication like data sharing on mobile, TV remotes, tablets, personal computers
(keyboards) etc. This wireless network example, in particular, can only be used for short-range,
i.e. 300GHz – 400THz. The IR communication functions only when the sender and the receiver
have an exchange of a light beam. Any disruption in it will cause the photo receiver not to
receive the signal. This also means that any object between the receiver and the transmitter will
cause a non-operation.
2. Wi-Fi
Wi-Fi also works as two-way communication and is used by several electronic devices like
smartphones, laptops and smart TV. In this process, the signal transmission works based on a
router. So, the network allows uninterrupted usage when in close proximity to a router. A range
of devices can be connected to one network at high speed. The only concern is that the Wi-Fi
network must be password protected for security reasons.
Today, Wi-Fi connection is easily available in cafes, restaurants, shopping malls, college
universities, and more places that are public. With a smooth connection, undoubtedly, one can
work at an exponential rate of quality and quantity.
3. Radio Frequency
Also popularly known as broadcast radio, here is the oldest type of wireless communication. It
can generate signals easily ranging from 3kHz to 300GHz. Unlike infrared communication, RF
transmission can happen through objects and travel long distances. Gladly, radio transmission
can penetrate through buildings, walls or anything else. Moreover, that’s how the popular radio
stations function.
From sharing some entertainment to passing some serious news information, this wireless radio
communication is beneficial and how. The proficient data transmitter can also help during
disasters. This network is commonly used to pass on any emergency information. The
communication depends highly on some of the parameters like sender power, receiver quality,
5
antenna height and wavelength. Radio frequencies are often known as the communication mode
for most government organizations. The only drawback is the dependency on frequency. In case
of bad weather, radio waves will be effective.
4. Bluetooth
Bluetooth wireless communication is not unknown to anyone. Surprisingly, in very little time,
everyone around is hooked on it. The functioning of the Bluetooth communication allows two
devices to connect for the data transfer (files, messages, music, images). Mobile phones can
easily be connected to Bluetooth headphones and have a wireless experience. Remember the old
times of using wired earphones? We have already bid adieu to them, isn’t it?
This wireless communication technology has a major drawback of distance. It can function
smoothly at a distance of a max of 30 feet.
5. Satellite communication
Here’s a type of wireless mode that holds significant importance globally. It is extensively used
to connect people anywhere in the world. This technology requires two dominant integrants: the
space and ground segments. Once the satellite receives a signal, it amplifies it and sends it back
to the receiver’s antenna, which is on Earth’s surface. The ground segment comprises a mobile
transmitter, receiver and the space segment (the satellite itself).
However, this crucial communication mode requires major testing before application.
6. Cellular communication
When we speak of what is wireless communication, this technology stands tall. It is one of the
most commonly used in our day-to-day life. Cellular communication allows transmission
through any mobile phone. The preset mode permits a dual way wherein the transmitter and
receiver can obtain signals simultaneously.
Cellular communication scores very high on convenience, and that’s why the use of video and
voice calls is growing by the day.
6
7. Microwave
Microwave wireless communication technology has a frequency range between 1GHz-300GHz.
This communication is routinely used in mobile phones and TV distribution. It is one of the most
rapid technologies and can carry about 2500 voice channels at one time. This type of wireless
communication can be used in the terrestrial or satellite method. However, it is unidirectional
and hence used in point-to-point communication. One weighty downside is that it can massively
be affected by bad weather.
Wireless vs Mobile Computing
Mobile and wireless systems really accomplish two very different things. While a wireless
system provides a fixed or portable endpoint with access to a distributed network, a mobile
system offers all of the resources of that distributed network to something that can go anywhere,
barring any issues with local reception or technical area coverage.
For another example of the difference between mobile and wireless, think of businesses that
offer Wi-Fi hotspots. A Wi-Fi hotspot is typically a resource for someone who has a relatively
fixed device, such as a laptop computer that doesn’t have its own internal Internet access built in.
By contrast, mobile devices already have inherent access to the Internet or other wireless systems
through those cell tower networks that ISPs and telecom companies built specifically for them.
So mobile devices do not need Wi-Fi – they already have their connections.
Advantages of Wireless Communication
There are numerous advantage of Wireless Communication Technology, Wireless Networking
and Wireless Systems over Wired Communication like Cost, Mobility, Ease of Installation, and
Reliability etc.
Cost
The cost of installing wires, cables and other infrastructure is eliminated in wireless
communication and hence lowering the overall cost of the system compared to wired
communication system. Installing wired network in building, digging up the Earth to lay the
7
cables and running those wires across the streets is extremely difficult, costly and time
consuming job.
In historical buildings, drilling holes for cables is not a best idea as it destroys the integrity and
importance of the building. Also, in older buildings with no dedicated lines for communication,
wireless communication like Wi-Fi or Wireless LAN is the only option.
Mobility
As mentioned earlier, mobility is the main advantage of wireless communication system. It
offers the freedom to move around while still connected to network.
Ease of Installation
The setup and installation of wireless communication network’s equipment and infrastructure is
very easy as we need not worry about the hassle of cables. Also, the time required to setup a
wireless system like a Wi-Fi network for example, is very less when compared to setting up a
full cabled network.
Reliability
Since there are no cables and wires involved in wireless communication, there is no chance of
communication failure due to damage of these cables, which may be caused by environmental
conditions, cable splice and natural diminution of metallic conductors.
Disaster Recovery
In case of accidents due to fire, floods or other disasters, the loss of communication
infrastructure in wireless communication system can be minimal.
Disadvantages of Wireless Communication
Even though wireless communication has a number of advantages over wired communication,
there are a few disadvantages as well. The most concerning disadvantages are Interference,
Security and Health.
Interference
Wireless Communication systems use open space as the medium for transmitting signals. As a
result, there is a huge chance that radio signals from one wireless communication system or
network might interfere with other signals.
8
The best example is Bluetooth and Wi-Fi (WLAN). Both these technologies use the 2.4GHz
frequency for communication and when both of these devices are active at the same time, there is
a chance of interference.
Security
One of the main concerns of wireless communication is Security of the data. Since the signals
are transmitted in open space, it is possible that an intruder can intercept the signals and copy
sensitive information.
Health Concerns
Continuous exposure to any type of radiation can be hazardous. Even though the levels of RF
energy that can cause the damage are not accurately established, it is advised to avoid RF
radiation to the maximum.
Applications of Wireless Communication
Applications of wireless communication involve security systems, television remote control, Wi-
Fi, Cell phones, wireless power transfer, computer interface devices, and various
wireless communication-based projects.
Wireless Communication Based Projects
Wireless communication-based projects mainly include different types of wireless
communication technologies like Bluetooth, GPS, GSM, RFID, and Zigbee projects
