Study on Air-Water & Water-Water Heat Exchange in a Finned Tube Exchanger
Consumer Electronics
1. MGM UNIVERSITY
JAWAHARLAL NEHRU ENGINEERING COLLEGE
ELECTRONICS & TELECOMMUNICATIONS DEPARTMENT
COURSE: CONSUMER ELECTRONICS(B.TECH.)
PROF. G. R. BASOLE
PROF. V. V. UKARANDE
2. COURSE OUTCOMES:
Classify various mobiles communication and related technologies.
Identify and explain working of various Colour TV transmission and
receiver blocks.
Illustrate operating principle of Home appliances and printer
technologies.
Describe working of special purpose machines and security devices.
Apply product electrical safety standards.
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3. INTRODUCTION TO SYLLABUS
CODE:BTETPE704A CREDIT:03
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Unit No Unit Name Brief Contents
1 Communication devices Mobile handsets, Android technology, 2G, 3G Mobiles,
i-phone, EPABX
2 Mass Communication
devices
Color Television, Antenna, HDTV, LCD TV,LED TV, 3D
Technology In TV, Interactive
TV, DTHTV, Plasma TV, Video Conferencing, FAX
Machine, PA System, Dolby Digital
Systems, Gesture Technology In TV.
3 Household Electronics
devices
Washing Machine, Microwave Oven, Types
Applications, Electronics Weighing Balance, Air
Conditioner, Vacuum Cleaner. Continued..
4. Unit No Unit Name Brief Contents
4 Printing and recording
devices
LASER printer, Inkjet Printers, Photocopiers, Scanner,
DVD/CD Player, Blue ray DVD
Player.
5 Special purpose
machines:
Security devices:
Electronic Voting Machine, CFL, LED Lamps, Application
and Advantages. Solar lamp,
Water Purifier, Electronic Calculator, DVD Player, ATM
Biometric attendance Monitoring System, Working,
Biometric Sensors, Home Automation
System.
6 Compliance: Product safety and liability issues, standards related
to electrical safety and standards related
to fire hazards, e.g., UL and VDE. EM1/EMC
requirements and design techniques for
compliance, e.g. ESD, RF interference and immunity,
line current harmonics and mains
voltage surge.
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5. CONTENTS OF UNIT-I
COMMUNICATION DEVICES
Mobile Handsets
Android Technology
2G Technology
3G technology
4G Technology
i-Phones
EPABX
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7. LEARNING OUTCOMES OF THIS LECTURE:
Student will be able to Learn:
Evolution of Mobile Handsets from 1983 to till date
Understand how specifications of Mobile handset changed over period of time
Internal Structure of Mobile Handset
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14. LEARNING OUTCOMES OF THIS LECTURE:
Student will be able to:
Identify Various Mobile Operating Systems and History of Android OS
Understand different version of Android OS
Explain Architecture of Android OS
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15. VARIOUS MOBILE OPERATING SYSTEMS
AND HISTORY OF ANDROID OS
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Blackberry
Symbian
Firefox OS
Windows
Android
iOS
16. HISTORY OF ANDROID
Initially, Andy Rubin founded Android Incorporation in Palo Alto, California,
United States in October, 2003.
In 17th August 2005, Google acquired android Incorporation. Since then, it is in
the subsidiary of Google Incorporation.
The key employees of Android Incorporation are Andy Rubin, Rich Miner,
Chris White and Nick Sears.
Originally intended for camera but shifted to smart phones later because of low
market for camera only.
Android is the nick name of Andy Rubin given by coworkers because of his love
to robot
In 2007, Google announces the development of android OS.
In 2008, HTC launched the first android mobile.
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19. ANDROID ARCHITECTURE
Android architecture is a software stack of components to support mobile device needs.
Android software stack contains a Linux Kernel, collection of C/C++ libraries which are
exposed through an application framework services, runtime, and application.
Following are main components of android architecture those are
Applications
Android Framework
Android Runtime
Platform Libraries
Linux Kernel
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22. 1. LINUX KERNEL
In these components, the Linux Kernel is the main component in android to
provide its operating system functions to mobile and Dalvik Virtual
Machine (DVM) which is responsible for running a mobile application.
Linux Kernel is a bottom layer and heart of the android architecture. It manages all
the drivers such as display drivers, camera drivers, Bluetooth drivers, audio drivers,
memory drivers, etc. which are mainly required for the android device during the
runtime.
The Linux Kernel will provide an abstraction layer between the device hardware
and the remainder of the stack. It is responsible for memory management, power
management, device management, resource access, etc.
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23. HARDWARE ABSTRACTION LAYER (HAL)
The hardware abstraction layer (HAL) provides standard interfaces
that expose device hardware capabilities to the higher-level Java API
framework.
The HAL consists of multiple library modules, each of which
implements an interface for a specific type of hardware component,
such as the camera or bluetooth module.
When a framework API makes a call to access device hardware, the
Android system loads the library module for that hardware component.
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24. 2. ANDROID RUNTIME
Android Runtime(ART) environment is an important part of Android rather than
an internal part and it contains components like core libraries and the Dalvik
virtual machine. The Android run time is the engine that powers our applications
along with the libraries and it forms the basis for the application framework.
Dalvik Virtual Machine (DVM) is a register-based virtual machine like Java
Virtual Machine (JVM). It is specially designed and optimized for android to
ensure that a device can run multiple instances efficiently. It relies on the Linux
kernel for threading and low-level memory management.
The core libraries in android runtime will enable us to implement android
applications using standard JAVA programming language.
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25. 3. PLATFORM LIBRARIES
The Platform Libraries includes various C/C++ core libraries and Java based libraries
such as Media, Graphics, Surface Manager, OpenGL etc. to provide a support for android
development.
Media library provides support to play and record an audio and video formats.
Surface manager responsible for managing access to the display subsystem.
SGL and OpenGL both cross-language, cross-platform application program interface
(API) are used for 2D and 3D computer graphics.
SQLite provides database support and FreeType provides font support.
Web-Kit This open source web browser engine provides all the functionality to display
web content and to simplify page loading.
SSL (Secure Sockets Layer) is security technology to establish an encrypted link
between a web server and a web browser.
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26. 4. APPLICATION FRAMEWORK
The Application Framework provides the classes used to create Android applications.
It also provides a generic abstraction for hardware access and manages the user
interface and application resources. It basically provides the services through which we
can create a particular class and make that class helpful for the Application creation.
The entire feature-set of the Android OS is available to you through APIs written in the
Java language. These APIs form the building blocks you need to create Android apps by
simplifying the reuse of core, modular system components and services.
The application framework includes services like telephony service, location services,
notification manager, NFC service, view system, etc. which we can use for application
development as per our requirements.
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27. A rich and extensible View System you can use to build an app’s UI, including lists, grids, text
boxes, buttons, and even an embeddable web browser
A Resource Manager, providing access to non-code resources such as localized strings, graphics,
and layout files
A Notification Manager that enables all apps to display custom alerts in the status bar
An Activity Manager that manages the lifecycle of apps and that includes the management of the
activities stack!
Content Providers that enable apps to access data from other apps, such as the Contacts app, or to
share their own data
Developers have full access to the same framework APIs that Android system apps use.
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How do I create APK files?
Android apps are developed using Android Studio, the official IDE for Android software
developers. It is available for Windows, Mac, and Linux, and it allows users to develop
apps and prepare them for upload to a distribution service, such as Google Play. When
apps are ready, developers can build them into APK files and sign them for release.
28. 5. APPLICATIONS
The top layer of the android architecture is Applications. The native and third-party
applications like contacts, email, music, gallery, clock, games, etc. whatever we will build
those will be installed on this layer only.
The application layer runs within the Android run time using the classes and services made
available from the application framework.
Android comes with a set of core apps for email, SMS messaging, calendars, internet
browsing, contacts, and more. Apps included with the platform have no special status among
the apps the user chooses to install. So a third-party app can become the user's default web
browser, SMS messenger, or even the default keyboard (some exceptions apply, such as the
system's Settings app).
The system apps function both as apps for users and to provide key capabilities that
developers can access from their own app. For example, if your app would like to deliver an
SMS message, you don't need to build that functionality yourself—you can instead invoke
whichever SMS app is already installed to deliver a message to the recipient you specify.
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29. .APK FILE
An Android Package Kit (APK for short) is the package file format used by the Android operating
system for distribution and installation of mobile apps. Just like Windows (PC) systems use an
.exe file for installing software, the APK does the same for Android.
When you download an APK online, you're essentially getting an app. Most users get apps from
the Google Play Store, without ever seeing the word APK. But there are occasions when you
would want to do otherwise.
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What does an APK file contain?
Android packages contain all the necessary files for a single Android program. Below is a list of the most
prominent files and folders:
META-INF/: Contains the manifest file, signature, and a list of resources in the archive
lib/: Native libraries that run on specific device architectures (armeabi-v7a, x86, etc.)
res/: Resources, such as images, that were not compiled into resources.arsc
assets/: Raw resource files that developers bundle with the app
AndroidManifest.xml: Describes the name, version, and contents of the APK file
classes.dex: The compiled Java classes to be run on the device (.DEX file)
resources.arsc: The compiled resources, such as strings, used by the app (.ARSC file)
31. LEARNING OUTCOMES OF THIS LECTURE:
Student will be able to:
Understand History of i-OS and i-Phones
Understand different version of i-OS
Explain Architecture of i-OS
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34. 1. CORE OS LAYER
The Core OS layer holds the low level features that most other technologies are built upon.
Core Bluetooth Framework.
Accelerate Framework.
External Accessory Framework.
Security Services framework.
Local Authentication framework.
• The Core OS layer provides a handful of frameworks that your application can use directly, such
as the Accelerate and Security frameworks.
• The Core OS layer also encapsulates the kernel environment and low level UNIX interfaces to
which your application has no access, for obvious security reasons. However, through the C-
based libSystem library many low level features can be accessed directly, such as BSD sockets,
POSIX threads, and DNS services.
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35. 2. CORE SERVICES LAYER
The Core Services layer is in charge of managing the fundamental system services that native iOS
applications use. The Cocoa Touch layer depends on the Core Services layer for some of its
functionality. The Core Services layer also provides a number of indispensable features, such as
block objects, Grand Central Dispatch, In-App Purchase, and iCloud Storage.
One of the most welcomed additions to the Core Services layer is ARC
or Automatic Reference Counting. ARC is a compiler-level feature, introduced in 2011
alongside the release of iOS 5. ARC simplifies the process of memory management in Objective-
C.
One should understand the basics of memory management when developing Cocoa applications.
Automatic Reference Counting is a great addition, but it's important that you know what ARC is
doing for you.
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36. 2. CORE SERVICES LAYER
Address book framework – Gives programmatic access to a contacts database of user.
Cloud Kit framework – Gives a medium for moving data between your app and iCloud.
Core data Framework – Technology for managing the data model of a Model View Controller app.
Core Foundation framework – Interfaces that gives fundamental data management and service features for iOS
apps.
Core Location framework – Gives location and heading information to apps.
Core Motion Framework – Access all motion based data available on a device. Using this core motion
framework Accelerometer based information can be accessed.
Foundation Framework – Objective C covering too many of the features found in the Core Foundation
framework
Healthkit framework – New framework for handling health-related information of user
Homekit framework – New framework for talking with and controlling connected devices in a user’s home.
Social framework – Simple interface for accessing the user’s social media accounts.
StoreKit framework – Gives support for the buying of content and services from inside your iOS apps, a feature
known asIn-App Purchase.
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37. 3. MEDIA LAYER
Graphics, audio, and video are handled by the Media layer. This layer contains a number of key
technologies, such as Core Graphics, OpenGL ES and OpenAL, AV Foundation, and Core Media.
Graphics Framework:
UIKit Graphics – It describes high level support for designing images and also used for animating the
content of your views.
Core Graphics framework – It is the native drawing engine for iOS apps and gives support for custom
2D vector and image based rendering.
Core Animation – It is an initial technology that optimizes the animation experience of your apps.
Core Images – gives advanced support for controlling video and motionless images in a nondestructive
way
OpenGl ES and GLKit – manages advanced 2D and 3D rendering by hardware accelerated interfaces
Metal – It permits very high performance for your sophisticated graphics rendering and computation
works. It offers very low overhead access to the A7 GPU.
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38. 3. MEDIA LAYER
Audio Framework:
• Media Player Framework – It is a high level framework which gives simple use
to a user’s iTunes library and support for playing playlists.
• AV Foundation – It is an Objective C interface for handling the recording and
playback of audio and video.
• OpenAL – is an industry standard technology for providing audio.
Video Framework
• AV Kit – framework gives a collection of easy to use interfaces for presenting
video.
• AV Foundation – gives advanced video playback and recording capability.
• Core Media – framework describes the low level interfaces and data types for
operating media.
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39. 4.COCOA TOUCH LAYER
EventKit framework – gives view controllers for showing the standard system interfaces for
seeing and altering calendar related events
GameKit Framework – implements support for Game Center which allows users share their
game related information online
iAd Framework – allows you deliver banner-based advertisements from your app.
MapKit Framework – gives a scrollable map that you can include into your user interface of
app.
PushKitFramework – provides registration support for VoIP apps.
Twitter Framework – supports a UI for generating tweets and support for creating URLs to
access the Twitter service.
UIKit Framework – gives vital infrastructure for applying graphical, event-driven apps in iOS.
Some of the Important functions of UI Kit framework:
-Multitasking support.
– Basic app management and infrastructure.
– User interface management
– Support for Touch and Motion event.
– Cut, copy and paste support and many more. 1 August 2020
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40. STRUCTURE OF AN IPA FILE
What is .ipa file ?
An . ipa (iOS App Store Package) file is an iOS application archive file which stores an
iOS app. Each . ipa file includes a binary and can only be installed on an iOS device.
There are three types of iOS applications:
Native applications uses Objective C/Swift for building the application
Hybrid applications use frameworks like Xamarin, Cordova etc. along with Objective
C/Swift.
Web based applications are responsive versions of websites built for working on
mobile device.
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43. USEFUL ABBREVIATIONS
• AMPS: Advance Mobile Phone Service(USA)
• NMT: Nordic Mobile Telephone(Scandinavian Countries)
• TACS: Total Access Communication System(UK)
• D-AMPS: Digital-Advanced Mobile Phone Service
• GSM: Global System for Mobile Communication
• GPRS: General Packet Radio Service
• EDGE : Enhanced Data Rates for GSM Evolution
• WCDMA : Wideband Code Division Multiple Access
• HSPA : High Speed Packet Access
• EV-DO: Evolution data Optimized
• CDMA: Code Division Multiple Access
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44. HISTORY OF 1G
This was the first wireless telecommunication generation used by the majority of the people for a long
time. These telephones were the first and the foremost mobile phones to be utilized. In 1979, 1G was
launched commercially in Tokyo city of Japan by NTT(Nippon Telegraph and Telephone)
DoCoMo firm. And within a span of 5 years, it spread across Japan widely.
Two years after 1G launched, in 1981 many Nordic countries like Norway, Sweden, Denmark, Finland,
Switzerland, Netherlands, Eastern Europe and Russia got new standards known as NMT(Nordic
Mobile Telephone) which were based on 1G technology.
Similarly AMPS (Advanced Mobile Phone System) started to be used in North America and
Australia, TACS (Total Access Communications Systems) in UK and many others.
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45. 1G MOBILE TECHNOLOGY
45
In 1970, Bell Labs in New Jersey
proposed a cellular telephone concept
as advanced mobile telephony system
(AMPS). AMPS is a standard cellular
telephone service placed into
operation on October 13, 1983, by
Illinois Bell. Frequency used is
30KHz.
AMPS uses frequency-division
multiple access (FDMA), where
transmissions are separated in the
frequency domain. Subscribers are
assigned a pair of voice channels
(forward and reverse) for the duration
of their call.
Bandwidth 150/900 MHz
Modulation scheme : FM
Problems:
Poor sound quality
Limited coverage
Full analog mode of communication,
hence inefficient use of the spectrum
Low capacity, FDMA technique does
not maximize system capacity
47. 2G MOBILE TECHNOLOGY
• 2G refers to the second generation of mobile networks based on GSM. The radio
signals used by the 1G network were analog, while 2G networks were digital. 2G
capabilities were achieved by allowing multiple users on a single channel via
multiplexing. Main motive of this generation was to provide secure and reliable
communication channel. It implemented the concept of CDMA and GSM .During 2G,
Cellular phones were used for data along with voice. Some of the key features of
2G were:
Data speeds of up to 64 kbps
Use of digital signals instead of analog
Enabled services such as SMS and MMS (Multimedia Message)
Provided better quality voice calls
It used a bandwidth of 30 to 200 KHz
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48. IN 2G, FIVE BIG FEATURES WERE ADDED AND IMPROVED
COMPARED TO 1G AND THEY ARE:
1) Data transmission for phone conversation got fully digitized and encrypted.
2) Internet data service and SMS like plain text, picture messages, MMS service were
initiated in addition to phone calls.
3) 2G enabled devices became more efficient to receive and send signals with higher
penetration levels for wide radio waves spectrum.
4) Better voice quality, more than one medium to communicate brought a new change in
wireless communication technology. With data encryption method, transmission became
more efficient and fast with better quality and data security. Only a particular
recipient could receive the intended message via encryption technique.
5) The mobile phone size also reduced to some extent. Battery life improved due to
digitization of data transmission which usually took less energy to transmit.
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49. WHAT IS TDMA ?
• Time Division Multiple Access
• In TDMA the available spectrum is partitioned into narrow frequency bands or
frequency channels, which, in turn, are divided into a number of time slots.
• In case of North American digital cellular standard IS-136,IS-95 each
frequency channel (30 kHz) is divided into three-time slots, whereas in
European digital cellular system GSM each frequency channel (200 kHz) is
divided into eight time slots. Guard bands are needed both between
frequency channels and time slots.
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50. 2.5G TECHNOLOGY-GPRS
• GPRS is a 2.5G technology implemented by GSM network operators to increase network
capacity UPTO 172 KBPS.
• The key element of GPRS technology was that it uses packet switched data rather than circuit
switched data, and this technique made much more efficient use of the available capacity.
This is because most data transfer occurs in what is often termed a "bursty" fashion.
• Using a traditional approach a circuit was switched permanently to a particular user. This is
known as a circuit switched mode.
• To achieve this, the data is split into packets and tags inserted into the packet to provide the
destination address. Packets from several sources can then be transmitted over the link. As it is
unlikely that the data burst for different users will occur all at the same time, by sharing the
overall resource in this fashion, the channel, or combined channels can be used far more
efficiently. This approach is known as packet switching, and it is at the core of many cellular
data systems, and in this case GPRS.
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51. 2.75G TECHNOLOGY-EDGE
• GSM EDGE cellular technology was an evolutionary upgrade to the existing GSM / GPRS
networks.
• EDGE uses 8PSK modulation technique. In 8PSK encoding, a single carrier symbol used to
carry 3 bits instead of 1 bit used in GPRS. This further improved voice conversation quality.
• EDGE or 2.75G is usually denoted by the E symbol near the mobile network.
data rate is 384 kbps.
• EDGE technology is an extended version of GSM. It allows the clear and fast transmission of
data and information. It is also termed as IMT-SC or single carrier. EDGE technology was
invented and introduced by Cingular, which is now known as AT& T. EDGE is radio technology
and is a part of third generation technologies. EDGE technology is preferred over GSM due
to its flexibility to carry packet switch data and circuit switch data.
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52. WHAT IS CDMA ?
• Code Division Multiple Access (CDMA) technology
• CDMA technology was originally developed for the US Army during the Vietnam
War, as a way of disguising conversations intended for military purposes. This
method separates different conversations by coding rather than by time sharing or
by frequency sharing (FDMA) as with the NAMPS technology. The method of
separation by coding enables conducting a large number of conversations
simultaneously over the same range of frequencies, with no interference between
them.
• "Qualcomm", which developed this technology, applied it to cellular communications
that use coded speech at different rhythms – a technology whereby the cellular
device receives simultaneous information from a number of base stations. This
technology ensures the continuity of conversations during movement from one cell to
another.
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55. 3G TECHNOLOGY
• UMTS technology, based on Wideband Code Division Multiple Access (W-CDMA) technology,
is one of the third-generation (3G) technologies of mobile phone telephony. This technology
was designed by the Third Generation Partnership Project (3GPP), Three standards based on
CDMA, namely CDMA2000, WCDMA, and TD-SCDMA.
• 3G is the next generation of wireless network technology that provides high speed bandwidth
(high data transfer rates) to handheld devices. The high data transfer rates will allow 3G
networks to offer multimedia services combining voice and data.
Data transfer rates:
• 2.05 Mbits/second to stationary devices.
• 384 Kbits/second for slowly moving devices, such as a handset carried by a walking user.
• 128 Kbits/second for fast moving devices, such as handsets in moving vehicles.
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57. WHAT ARE THE ADVANTAGES OF 3G?
• New radio spectrum to relieve overcrowding in existing systems.
• More bandwidth, security, and reliability.
• Interoperability between service providers.
• Fixed and variable data rates.
• Asymmetric data rates.
• Backward compatibility of devices with existing networks.
• Always-online devices. 3G will use IP connectivity, IP is packet based (not circuit based).
• Rich multimedia services.
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59. 4G TECHNOLOGY
• 4G stands for 4th Generation Technology, and it is a venture to develop, incorporate the
current 2G , 3G, WLAN, short-range, fixed wire systems into a single and broadcast, entirely
functional, consistent and coherent internetwork.
• It is an extension of 3G technology which provides capabilities defined by ITU (International
Telecommunications Union) in IMT (International Mobile Telecommunications) includes
features like scalability, flexibility, efficiency, self-governance, security to support interfacing
with different types of networks and a multitude of new and existing services.
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60. ABOUT LTE AND WIMAX
• LTE stands for “Long Term Evolution,” and is an ITU-approved 4G mobile broadband technology. It
is a direct competitor to WiMax. LTE is more of a successor to current mobile 3G standards than
WiMax. However, instead of transmitting data using microwaves, LTE uses radio waves. WiMax
stands for “Worldwide Interoperability for Microwave Access.”
• Both LTE and WiMax use the principle of Orthogonal Frequency-Division Multiple Access, which
conceptually has been around since the 1960s. OFDMA is based on the idea of frequency-division
multiplexing, which is a method to transmit multiple data streams over a channel. In case of
OFDMA, a digital data stream that needs to be transmitted is split into multiple pieces, each of
which is modulated onto a separate carrier. These sub-carriers are combined together at the end.
• The difference between LTE and WiMax lies in how they handle the channel for processing data.
WiMax processes all the information in a wide channel. In case of Clearwire's implementation of
WiMax, that means the about two-thirds of the channel is used for downloads, while a third is used
to upload data.
• LTE splits the channel into two parts using frequency-division multiplexing, so the download and
upload speeds are better balanced.
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61. ABOUT OFDM
• OFDM forms the basic signal format used within 4G LTE. OFDM, Orthogonal Frequency Division
Multiplex is the basic format used and this is modified to provide the multiple access scheme:
OFDMA, orthogonal frequency division multiple access in the downlink and SC-FDMA, single
channel orthogonal frequency division multiple access in the uplink.
• Using multiple carriers, each carrying a low data rate, OFDM is ideal for high speed data
transmission because it provides resilience against narrow band fading that occurs as a result of
reflections and the general propagation properties at these frequencies.
• Within the basic LTE OFDM signal format a variety of modulation formats are used including PSK
and QAM. Higher order modulation is used to achieve the higher data rates: the modulation order
being determined by the signal quality
• One of the key parameters associated with the use of OFDM within LTE is the choice of bandwidth.
The available bandwidth influences a variety of decisions including the number of carriers that can
be accommodated in the OFDM signal and in turn this influences elements including the symbol
length and so forth.
• LTE defines a number of channel bandwidths. Obviously the greater the bandwidth, the greater
the channel capacity
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62. ABOUT MIMO
• MIMO is a form of antenna technology that uses multiple antennas to enable signals travelling
via different paths as a result of reflections, etc., to be separated and their capability used to
improve the data throughput and / or the signal to noise ratio, thereby improving system
performance.
• The basic concept of MIMO utilizes the multipath signal propagation that is present in all
terrestrial communications. Rather than providing interference, these paths can be used to
advantage.
• The transmitter and receiver have more than one antenna and using the processing power
available at either end of the link, they are able to utilise the different paths that exist
between the two entities to provide improvements in data rate of signal to noise.
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63. FEATURES OF 4G
• 4G has higher capacity, meaning it can support a greater number of users at any given time.
It sports higher data rates, so that multimedia applications such as video calling or YouTube
clips work more smoothly. With a 3G tower, about 60 to 100 people can share the signal and
get fast, reliable service. A 4G LTE (Long Term Evolution) tower, however, can serve around
300 or 400 people.
• And 4G features reduced latency. With less latency, or delay, you see more immediate
response to your commands, which is especially helpful when you're playing fast-paced online
games or remotely controlling a car or robot. A network that qualifies as real-time speed has
a latency of 50ms (milliseconds) or less; 4G LTE has a latency of only around 20 to 40ms. Low
latency also means voice calls don't have any lag or echo.
• 4G is more spectrally efficient than 3G. Think of radio spectrum as a pipe of a certain
diameter; only so much data can go through that pipe at one time. But 4G uses clever coding
schemes to dramatically increase the amount of data that rushes through the spectrum.
Ultimately, it delivers more bits per hertz than 3G.
1 August 2020 63
