Mobile devices


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Mobile Devices - Mobile Computing

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Mobile devices

  2. 2. 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
  3. 3. 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.
  4. 4. 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
  5. 5. 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.
  6. 6.  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
  7. 7. Popular Audio File Formats 1. 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
  8. 8. 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
  9. 9. 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.
  10. 10. 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
  11. 11. 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
  12. 12. 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
  13. 13. 4. Operating Systems in Handheld Devices  Windows CE  Palm OS  Symbian OS  Linux for Mobile Devices  Android  iOS  Blackberry Etc.
  14. 14. 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.
  15. 15. 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
  16. 16. 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
  17. 17.  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
  18. 18. 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
  19. 19. 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
  20. 20. 5. Smart Systems  Smart cards  Sensors and Actuators .. Already Taken
  21. 21. 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.)
  22. 22. 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
  23. 23. 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
  24. 24. 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.
  25. 25. 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
  26. 26. 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
  27. 27. 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
  28. 28. 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]
  29. 29. Thank You .. Questions ??