Lecture 01-Introduction to wireless communication.pdf

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Lecture# 01
Introduction to wireless communication
Dr. Shahzad Ashraf
Associate Professor
Ancient Communications are wireless

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Modern Era of Wireless Communications
 The transmission of information between two or more points without physical
connections such as mobile phones, Wi-Fi, Bluetooth, satellite communication etc
 Guglielmo Marconi invented the wireless telegraph in 1896
 He communicated by encoding alphanumeric characters in analog signal and sent
telegraphic signals across the Atlantic Ocean
 Electromagnetic waves (EW) are fundamental to wireless communication, as they
serve as the primary medium for transmitting information through the air
Role of EW
Transmission Medium: EW carry information across distances, from just a few meters
(like Wi-Fi) to thousands of kilometers (satellite communication). They travel at the
speed of light, allowing for quick transmission.
Information Encoding: Data is encoded onto electromagnetic waves through
modulation techniques, where specific properties of the wave (such as amplitude,
frequency, or phase) are adjusted to represent digital or analog signals.

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Role of EW
Frequency Bands and Range: Different frequencies within the electromagnetic
spectrum are allocated for various types of communication (e.g., radio, microwave,
infrared). Lower frequencies, like radio waves, travel farther but have lower data rates,
while higher frequencies, like microwaves, offer higher data rates but shorter range.
Propagation Characteristics: The propagation is influenced by factors such as
atmospheric conditions, obstacles, and frequency. Lower frequencies can penetrate
buildings and obstacles better, which is why they are commonly used for mobile
communication.
Signal Interference and Attenuation: EW waves can be affected by interference from
other devices and attenuation due to obstacles, which can weaken the signal.
Techniques like beamforming, channel hopping, and error correction are used to
mitigate these issues
Components of wireless communication

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Basic terms in wireless communication
Frequency
o The number of oscillations of a wave per second, measured in hertz (Hz)
o Different frequency bands (e.g., radio, microwave) are used for various types of wireless
communication.
o The primary difference between radio waves and microwaves lies in their frequency and
wavelength ranges, but they also have different applications and propagation characteristics
o Radio Waves typically have lower frequencies, ranging from about 3 kHz to 300 GHz, and
longer wavelengths, from about 1 millimeter to 100 kilometers.
o Radio Waves: Used in broadcasting (radio and TV), AM/FM radio, and low-frequency
communication, including maritime and aeronautical communication.
o Microwaves are the subset of radio waves with higher frequencies, ranging from 300 MHz to
300 GHz, and shorter wavelengths, between 1 millimeter and 1 meter.
o Microwaves: Utilized in Wi-Fi, Bluetooth, satellite communication, radar, and microwave
ovens, where they can penetrate and heat food by exciting water molecules.
Propagation
o The tendency of radio waves to travel from one point to another or into various
parts of the atmosphere.
o The radiated signal from the transmitter reaches the receiver in three different
modes

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Multipath Propagation
o The transmitted signal takes multiple paths to reach the receiver, often due to
reflections, diffraction, and scattering
Effects of Multipath Propagation
Fading
o The signal strength fluctuates due to various environmental factors
o These fluctuations, known as fades, can result from interference, obstacles, or
natural changes in the environment, leading to variations in received signal quality.
o Fading is also referred to gradual loss of certain quality/ parameters and merely
disappears over the period of time

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Shadowing
o The variation in signal strength caused by large obstacles in the environment, such
as buildings, hills, and trees, that block the direct line of sight (LOS) between the
transmitter and receiver.
Basic elements in communication system

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Transmission Media
The physical pathways through which data is transmitted from one device to another in
a network
Guided Media
Twisted Pair Cable: Comprises pairs of insulated copper wires twisted together commonly
used in telephone networks and local area networks (LANs).
Coaxial Cable: Contains a central conductor, an insulating layer, a metallic shield, and an
outer insulating layer. It’s used for cable television and broadband internet.
Fiber Optic Cable: Uses glass or plastic fibers to transmit data as light signals. It offers high
bandwidth and is immune to electromagnetic interference, making it suitable for long-
distance communication.
Unguided Media
o Radio Waves
o Microwave
o Infrared
Transmission and reception are achieved by means of an antenna and configured either as
directional or Omnidirectional
Types of Wireless Network
Wireless networks can be categorized based on various factors, such as range,
architecture, and the technologies used
o Wireless Local Area Network (WLAN)
--Commonly uses Wi-Fi standards (IEEE 802.11)
o Wireless Wide Area Network (WWAN)
--Covers a larger geographical area than a WLAN, using cellular technology
to connect devices over long distances
--Utilizes mobile network standards such as 3G, 4G, and 5G
o Wireless Personal Area Network (WPAN)
--connects devices within a very short range, typically within a few meters
--Common technologies include Bluetooth, Zigbee, and Near Field
Communication (NFC)
o Satellite Network
--provide wireless communication over vast distances, including rural and
remote areas where other types of connectivity may not be feasible

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Switching difference
Switching in guided and unguided communication involves different mechanisms and
technologies due to the inherent differences between the two mediums
Types of Switching in wireless networks
Packet Switching: Similar to wired networks, but packets can be subject to
delays and loss due to interference, multipath propagation, and varying signal
strength.
Connection-Oriented vs. Connectionless: Wireless networks often employ both
types, with protocols adapting to conditions. For example, cellular networks may
use connection-oriented switching for voice calls.
Dynamic Topology: Wireless networks have a more dynamic topology since
devices can join or leave the network at any time. This requires more complex
algorithms for managing connections and routing data.
Limitations and difficulties
 Wireless is convenient and less expensive
 Limitations and political and technical difficulties inhibit wireless technologies
 Device limitations
 E.g., small LCD on a mobile telephone can only displaying a few lines of text
 E.g., browsers of most mobile wireless devices use wireless markup language
(WML) instead of HTML
 Switching speed of the material (e.g., silicon)
 Limited bandwidth
 Broadcast medium: requires multiple access schemes
 Variable link quality (noise, interference)
 High latency, higher jitter
 Heterogeneous air interfaces
 Security: easier snooping
 Battery Life

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Evolution of Wireless Technology
The evolution of wireless technology has significantly transformed how to communicate,
with each generation (1G to 5G, and the emerging 6G) introducing new capabilities,
improvements in speed, efficiency, and connectivity
GPRS (General Packet Radio Service)
 GPRS was launched in late 90s, is a mobile data service that provides wireless data
communications over the Global System for Mobile Communications (GSM)
 Uses packet switching technique allowing for more efficient use of bandwidth
 Users could remain connected without needing to establish a dedicated connection,
making it suitable for mobile internet access
 It enhanced the multimedia messaging (MMS) services alongside traditional SMS
EDGE (Enhanced Data rates for GSM Evolution)
 It was launched in early 2000s, utilized more advanced modulation techniques
(8PSK) to enhance data transmission rates
 Provided better spectral efficiency, allowing more users to share the same channel
 Served as a transitional technology between 2G and 3G, paving the way for more
robust mobile internet services.

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Universal Mobile Telecommunications System (UMTS)
 Utilized Wideband Code Division Multiple Access (WCDMA), enabling
simultaneous voice and data transmission.
 Supported more users with higher data rates, improving mobile broadband access.
 Enabled video calling, mobile TV, and other multimedia applications.
 Speeds ranging from 384 kbps to several Mbps, with the potential for even higher
rates in later releases (HSPA and HSPA+).
Long-Term Evolution (LTE)
 Transitioned to an all-IP architecture (all data, including voice and multimedia
services, is handled as IP packets across the entire network), optimizing data
transmission and reducing latency.
 Introduced MIMO (Multiple Input Multiple Output) and OFDMA (Orthogonal
Frequency Division Multiple Access) to enhance capacity and efficiency.
The End

Lecture 01-Introduction to wireless communication.pdf

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