mobile devices
DESCRIPTION
Mobile Devices - Mobile ComputingTRANSCRIPT
MOBILE COMPUTING SEMINAR
By : Rounak Jain
SOE, CUSAT
2. MOBILE DEVICES
1.Mobile Phones
2.Digital Music Players
3.Handheld Pocket Computers
4.Operating System used in Mobile Devices
5.Smart Systems
6.Limitations of Mobile Devices
2. Mobile Phones
Communicate with other phones using a cellular service-
provider network.
Packed with smart functions and are available in smaller sizes.
Applications of mobile phones no longer confined to telephonic
communication.
Can synchronize and upload and download data to and from
PCs.
Provides e-mail and Internet connectivity.
Even click pictures and prepare albums.
Includes a personal information manager (PIM), a handheld
computer, and an entertainment device.
New Generation Mobile Phones
Pack in everything from a computer to
an FM radio and from video recording
to TV viewing.
Smart Phones
Multimedia Phones
Apple iPhones
2. Digital Music Players
Revolutionized the way people listen to music
Includes software that play music files encoded in
formats such as MP3, WMA, Realmedia etc. on mobile,
PCs, and laptops.
Windows Media Player, QuickTime Player are some
examples of media-playing software.
Also include media-playing hardware or handheld (
portable ) music players that can play media file formats
such as MP3, AAC, WMA, WAV etc.
Such Players use flash Memory
Capacity may vary from 128 MB to 80 GB
Present day media players enable video as well as audio
Playback
Market Leader – Apple iPods
Popular Audio File Formats1. WAVE
Short for Waveform Audio, is a Microsoft and IBM audio
format
Audio format standard for storing audio .
Usually contains uncompressed audio in the PCM ( Pulse-
code Modulation ) form but they are also capable of holding
compressed audio.
Used by professionals for maximum audio quality and can
manipulated quite easily for storing compressed audio.
Supports a variety of bit resolutions, sample rates, and
channels of audio
2. RealAudio
Format developed by RealNetworks
Uses both low-bitrate formats for use over dial-
up modems and high-fidelity formats for music
Also serve as a streaming audio format which
can be played while it is being downloaded
Official playing software for RealAudio file format
is the RealPlayer
3. MP3
MP3 ( MPEG-1 audio layer 3) is one of the most
popular digital audio encoding and compression
format.
Uses lossy data compression
Designed to reduce the size of audio files to about
10% of the original uncompressed files without
compromising too much on sound quality.
Became an ISO/IEC standard in 1991.
Some Other Audio Formats are WMA, AAC etc.
3. Handheld Pocket Computers
Handheld Computers or Palmtops Come in many manifestations
For example, the smart phone
Pocket-sized PCs
Differ from smart phones and multimedia phones in that they can be
programmed for customized applications
Offer a variety of application and programming tools not included in new
generation mobile phones
Unlike smart phones, which usually use the text-on-nine-keys format,
handheld computers have full text keypad or a touch screen keypad.
Stylus generally used to enter data into handheld devices such as PDAs
and palmtops.
Some allow the user to write on the screen using a stylus and
incorporate special software for handwriting recognition
Palmtops
Programmable pocket computers
Include word processors and spread sheet software as
well as PIM software
QWERTY keyboards or touch screens with stylus for data
inputs
Difference b/w Pocket Computers and Laptops, notebooks
Pocket PCs no CD drives and hard disks
Use flash memory
Allow the insertion of a memory stick (A memory stick is a
removable flash memory card.)
Clock speeds of pocket computer processors are limited up to
200 MHz due to considerations about battery life
Unlike laptops and notebooks, which use regular
microcomputer operating systems, pocket computers have
specially designed operating systems which are scaled to the
requirements of the software, hardware, and peripherals used
in handheld computers
4. Operating Systems in Handheld Devices
Windows CE
Palm OS
Symbian OS
Linux for Mobile Devices
Android
iOS
Blackberry
Etc.
Windows CE
An operating system from Microsoft
Support multitasking on handheld devices
Real-time operating system meant for handheld computers and
embedded systems
Kernel different from the kernel of the desktop versions of Windows
Computing devices with low storage and can be run in about 1 MB
of memory.
But the Windows CE OS memory needs are larger as compared to
Palm OS
Support a wider range of hardware than Palm OS.
Support different CPUs such as NEC MIPS, Intel StrongARM, AMD
X86, etc.
Features in Windows CE Devices
High resolution colour/ display, touch screen and stylus keypad
Complex APIs
Gives the user a PC like feel and Windows like GUIs
PIM, MS Office, Internet Explorer features on handheld mobile system
The CompactFlash card slots to extend memory and extension card
slots
OS memory requirement is large but scales to the requirement of the
device peripherals
Digital camera card
Games
Microsoft Windows Media player and other media players
Palm OS
An operating system from Palm Inc
Used in smart phones and handheld computing devices
Optimized to support a very specific range of hardware ─ CPU,
controller chips
Screens of Palm OS based devices cannot be much different from
the hardware reference platform designed by Palm Computing
without major changes in the operating system itself
Advantageous in that that, because it is compiled for a specific set
of hardware, its performance is very finely tuned
Inability to adapt to different sorts of hardware
Does not support multitasking
Is definitely not a great platform for running multimedia
applications
Works efficiently when running small productivity
programs but doesn’t offer much expandability.
Palm OS devices usually have wide screens and input of
data is facilitated by a touch screen
PalmOne tungsten T5 Handheld
Symbian OS Was one of the most widely used operating system for smart
phones
Runs exclusively on ARM processors
Structure much like that of some desktop operating systems
Offers pre-emptive multitasking, multithreading
Memory protection
Initially designed for handheld devices with limited resources,
strongly emphasizes on memory conservation
Embodies event-based programming and when applications are
not directly concerned with events, the CPU is switched off
Such techniques are very useful in conserving battery life
Linux for Mobile Devices
Linux can be modified easily to suit different sorts of
hardware and software applications
Being an open source OS, it enables the user to customize
their device to suit their specific needs
Considered to be more secure than most other operating
systems.
Linux support is easily available from the many forums and
associations that promote this OS
Many international mobile phone manufacturers turning to
Linux for their OS requirements
5. Smart Systems
Smart cards
Sensors and Actuators ..
Already Taken
6. Limitations of Mobile Devices
1. Quality and Security of service Constraints
Technical restrictions and practical considerations─ difficulties in mobile device
uninterrupted operations
Maintaining quality of service along with the provisioning of seamless access to all
users
2. Accessibility constraints
Smart labels on packages limited access─ transmitted signals low power
Labels can only be read from very short ranges
RFID access limited to ranges within line of sight
RFID transmissions require hotspots close by due to low transmitted signal
strength. (A hotspot is an access point an interface for mobile systems, sensing
systems, and embedded systems to connect to a mobile network, wireless LAN, or
the Internet.)
3. Range Constraints
Signal strength inversely proportional to the square of the distance
Degradation of signal quality due to reflection, scattering, and diffraction
Access range limited to the range up to which the signal strength is such
that it can be separated from the noise and up to which multi-path delays
can be compensated for by digital signal processing techniques to restore
signal quality
4. Connectivity
Connectivity loss or intermittent connectivity in certain situations
The atmospheric conditions changes in environment affect signal strength
Water attenuation of UHF and near microwave
For example, in the event of heavy rain, there may be complete loss of
connectivity
5. Security constraints
Unsolicited advertisements and unwanted messages
Virus attacks
Hackers render it functionless or threaten integrity and
security of the data stored on the device
Noise signals transmitted by an attacker can jam a mobile
device
Repeated transmission of unwanted signals by an attacker
can drain the resources of the device
Energy resources depleted fast when computations are
forced and authentication algorithms are run repeatedly
6. Mobility Constraints
Non-availability of an access point or base station
Infrastructural issues
No base stations or Wi-Fi hotspots providing connectivity and
access to the Internet to sensors, labels, automotive systems,
RFID tags, and cell phones
Use of different standards in different regions limits the
operability
A GSM phone may not be operable in all continents hence
hampering global roaming for the user
Some service providers may not be able to provide connectivity
in all parts of the country or in other continents, etc.
7. Energy Constraints in Devices
Limited energy in battery. Battery size and power limited due to
considerations such as size, weight, and bulk of mobile devices
The devices need to be recharged after short periods of time. In this way
energy availability also limits device mobility.
Some devices such as smart cards, smart labels, remote sensors, and
actuators do not even have a battery of their own. They derive their
energy from the radiation received from a wireless source in vicinity. Such
devices, therefore, require these sources to Operate
Some devices such as smart cards, smart labels, remote sensors, and
actuators do not have a battery of their own.
They derive their energy from the radiation received from a wireless
source in vicinity. Such devices require these sources
8. Hardware Limitations
Constraints on memory
Innovative forms of memory designed and are continuously improved
upon.
Internal flash drives and the card slots for external memory used
Memory stick used to enhance the memory in the device
Large memory capacity─ 30GB video memory in mobile devices in a
recent enhancement of the Apple iPod
9. Bandwidth Limitations
Limited by the frequency spectrum that a regulator allots to a service
provider
The service must use the frequency spectrum allotted to it in an
efficient manner
University Questions
Operating Systems used in Mobile Devices ( 15 Marks) –
April 2010
What are the features desired in Mobile OS as compared
to desktop PCs ( 7 Marks ) – Sep 2011 Supplementary
Different types of audio file formats ( 5 Marks ) – Sep
2010 Supplementary
References
[1] Mobile Computing by Raj Kamal
[2] Xiang Yang, Yuanyi Zhang, Qinzhou Niu, Xiaomei
Tao, Luo, “A Mobile-Agent-Based Application Model
Design of Pervasive Mobile Devices”, Pervasive
Computing and Applications, 2007, ICPCA 2007.
[3] http://en.wikipedia.org/wiki/Audio_file_format
Thank You .. Questions ??