Mobile and wireless computing


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Mobile and wireless computing

  2. 2. Mobile Computing Also called nomadic, tetherless, wireless, ubiquitous, remote computing User does not need to maintain a fixed position in the network Useful for persons who travel away from their primary work place
  3. 3. Mobile Computing Mobile computing is "taking a computer and all necessary files and software out into the field.“ Mobile commerce is any transaction, involving the transaction having monetary value, which is initiated and/or completed by using wireless electronic device such as mobile phones, PDAs, pagers etc. and mobile telecommunication network. It is subset of e-commerce.
  4. 4. Mobile & Wireless Computation Wireless & Mobile are not synonymous Wireless  Isa transmission or information transport method that enables mobile computing  Communication is without wires MobileComputing focuses on the applications side .  Ability to compute no matter where the user is  Infrared, cellular, radio waves, microwave, satellite services
  5. 5. Mobile Computing Framework Wireless delivery technology Mobile Information Access Devices Mobile Data Internetworking standards and equipment Mobile computing based business applications
  6. 6. Wireless delivery technology1. Radio-Based Systems2. Infrared or mobile based computing
  7. 7. Radio-Based Systems  Thesesystems use radio frequency (RF) signals that range from 100 KHz to 20 GHz  RF communication is of 3 types  One way  Two way  Local way
  8. 8. Cont… Radio-Basedservices can be grouped in two main categories 1. Land Based  Cellular Communications  Wireless Packet Data networks(GPRS) 1. Satellite Based(Satellite Networks)  Very Small Aperture Terminals(VSATs)  Paging and Satellite networks
  9. 9. Cellular Communications In cellular system, the area of coverage is divided in to hexagonal cells that overlap at the outer boundaries Communication takes place with the help of transceivers A signal from the handset goes to nearest cell through telephone lines The size of cell is 2-10 miles Working
  10. 10. Wireless Packet data networks Uses packet techniques for transferring data Packet radio is a communication method used to transmit packets of data over network via RF signals These services were designed with data only in mind Working
  11. 11. Satellite Networks Used for global communication(broadcast) Useful where data need to be dispersed or gathered from many remote nodes and end to end delay is not of concern Cost effective Reliable Suitable for remote areas where poor or non existent phone services Disadv: poor choice for systems where a high degree of security is required
  12. 12. Very small apertureterminals(VSATS) Uses a large no. of small dishes called VSATS for outlying nodes and one central hub with a big dish. This approach causes additional delay Typically used by the organizations that require data or voice communication between sites distributed over a wide geographical area
  13. 13. Paging and satellite networks Oldest form of mobile communication (1949) One way mobile communication services Wireless communications Working Used for news, sports, weather, stock information etc at scheduled intervals
  14. 14. Infrared or light based mobilecomputing Works by sending pulses of light from a LED to a photo sensor that diverts signals Computing devices can send as well as receives signals Types of infrared equipments  Low speed (115 kbps- 250 kbps)  High speed (about 1.25 mbps) There should not be any physical obstructions between sending and receiving Cost effective
  15. 15. Mobile Information AccessDevices Portable Computers  Laptops,Notebooks,Handhelds Hybrid Pen Computers Personal Digital Assistants(PDAs)
  16. 16. Mobile Data Internetworkingstandards and equipmentReasons for analog to digital transition: Limited available bandwidth OvercrowdingCurrent analog system divides the available spectrum into 30 KHz wide channels.
  17. 17. Cont…Technologies for multiple Channel Access CDMA(Code Division Multiple Access)  Isa wideband spread-spectrum technology  Uses specialized codes as the basis of channelization(division of the frequency spectrum into multiple channels) TDMA(Time Division Multiple Access)  GSM(Global System for Mobile Communications ) is a type of TDMA  Addsa time sharing of 3 users on each frequency)
  18. 18. Mobile computing based businessapplicationsIt is resulting in two changes: Remote Communications Remote data accessApplications: Health care Retail Field service Traveling professionals Sales and service
  19. 19. Cont…Applications: Members of work groups Stock and commodity training
  20. 20. Technical and other limitations ofmobile computing Insufficientbandwidth Security standards Power consumption Transmission interferences Potential health hazards Human interface with device( ing)
  21. 21. Mobile Data Internetworkingstandards and equipment Consider a room (channel) in which people wish to communicate with each other. To avoid confusion,  people could take turns speaking (time division),  speak at different pitches (frequency division),  or speak in different directions (spatial division).  In CDMA, they would speak different languages. People speaking the same language can understand each other, but not other people. Similarly, in radio CDMA, each group of users is given a shared code. Many codes occupy the same channel, but only users associated with a particular code can understand each other.