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Chapter

chp 7. wireless, mobile computing and mobile commerce

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Department
Administrative Studies
Course
ADMS 2511
Professor
Anita Patel
Semester
Fall

Description
CHAPTER 7. WIRELESS, MOBILE COMPUTING, AND MOBILE COMMERCE. Wireless: telecommunication in which electromagnetic waves in the form of wire or cable, carry signal between communicating devices. Wireless Mobile Without wires. Can be mobile or fixed. Changes location over time. Traditional- fixed computer ineffective or inefficient. Wireless technologies- mobile computing, mobile commerce, and pervasive computing. Mobile computing: real time, wireless connection between a mobile device and other computing environments such as intranet/extranet. Mobile commerce/m-commerce: EC transactions conducted in a wireless environment, especially via internet. Pervasive computing/ubiquitous computing: means that virtually every object has processing power with wireless or wired connections to a global network. WIRELESS TECHNOLOGIES Wireless devices: advantages: Saves time that can be used effectively for some useful purpose Mobile- makes it flexible for a person to go anywhere with the devices. Allocate working time between personal and professional obligations. WAP: wireless application protocol (WAP) is the standard that enables wireless devices to access web-based information and services. Micro browsers: internet browsers with a small file size that can work within the confines of small screen sizes on wireless devices and relatively low bandwidths of wireless networks. Eg. Apple iphone- safari browser. Smart phones- cellular telephony, Bluetooth, Wi-Fi, a digital camera, global positioning system(GPS), an organizer, a scheduler, an address book, calculator, access to e-mail, Short message service(SMS), instant messaging, text messaging, mp3 music player, video player, internet access with full function browser, QWERTY keyboard. Disadvantages- Lack of privacy- user can copy and pass confidential information. Jamming devices- jam signals from phones when they enter specific locations. Wireless transmission media: wireless media/broadcast media transmit signals without wires over the air or space. Channel Advantages disadvantages Microwave High bandwidth Must have unobstructed line of microwave transmission Relatively inexpensive sight systems high volume, long Susceptible to environmental distance, line-of-sight interference, severe weather communication conditions. Satellite High bandwidth Expensive Satellite transmission systems Large coverage area Must have unobstructed line of make use of communication sight signals experience satellites. propagation delay Must use encryption for security Radio High bandwidth Creates electrical interference Signals pass through walls problems. Inexpensive and easy to install Susceptible to snooping unless encrypted Infrared Low to medium bandwidth Must have unobstructed line of Used only for short distances sight Microwave: towers cannot be spaced more than 50km apart. Satellite: 3 basic types of satellites- Type Characteristics Orbit Numb Use er Geostation Satellites remain stationary relative to point35900km 8 TV ary on earth signal (GEO) Few satellites needed for global coverage* Transmission delay (approx. 0.25sec-also called propagation delay) Most expensive to build and launch Longest orbital life(many years)* Medium Satellites move relative to the point on earth10354km 10-12 GPS earth orbit Moderate no. Needed for global coverage (MEO) Requires medium-powered transmitters Negligible transmission delay* Less expensive to build and launch* Moderate orbital life ( 6-12years) Low earth Satellites move rapidly relative to point on 640- Many telepho orbit earth 1125km ne (LEO) Large number needed for global coverage Requires only low-power transmitters Negligible transmission delay* Least expensive to build and launch* Shortest orbital life( as low as 5 years) Advantages* Geo satellite orbit has a fixed position right above the earths equator, thus its orbital period matches 24hrs rotation of the earth. Leo has the ability to pick up weak transmissions-satellite telephone to operate. A single organization often produces multiple Leo satellites- known as LEO constellations. Eg. Iridium has Leo constellations in orbit that consist of 66 satellites and 12 in-orbit square satellite Two major satellite applications-1) Global positioning system (GPS): wireless system that uses satellites to enable users to determine their position anywhere on earth. Has 24MEO satellites shared worldwide. Known speed of signals and distance between various signals- locates position and finds user/ receiving station within 3 metres. Converts users latitude longitude to electronic map for driving directions. Russian GPS- GLONASS by 1995 but failed. European Union GPS- Galileo by 2013 China GPS- Beidou by 2015 2) Internet transmission via satellites (IoS): installing necessary cables are expensive / physically impossible). Enables users to have access to GEO satellite internet using a dish mounted on the side of their homes. Disadvantage is disruption due to propagation delay and weather conditions. Microwave transmission- within line of sight. But earth has a huge footprint:
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