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Administrative Studies
ADMS 2511
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Chapter 7Wireless Mobile Computing and Mobile CommerceWireless is a term used to describe telecommunications in which electromagnetic waves rather than some form of wire or cable carry the signal between communication devices computer PDAs cell phone etcMobile Computing refers to a realtime wireless connection between a mobile device and other computing environments such as the internet or an intranet Mobile Commerce MCommerce refers to ecommerce EC transactions that are conducted in wireless environment especially via the internet Pervasive Computing Ubiquitous Computing means that virtually every object has processing power with wireless or wired connections to a global network Wireless technologies include both wireless devices and wireless transmission media Wireless devices are small enough to easily carry or wear have sufficient computing power to perform productive tasks and can communicate wirelessly with the Internet and other devicesAdvantages of wireless deviceoCan make productive use of time that was formerly wasted work in cars or public transportationoWork locations become much more flexible oEnable to allocate working time around personal and professional obligations Wireless Application Protocol WAP is the standard that enables wireless devices with tiny display screens low bandwidth connections and minimal memory to access Webbased information and servicesMicrobrowsers are internet browsers with a small file size that can work within lowmemory constraints of wireless devices and the low bandwidths of wireless networksWireless Devices include pages email handhelds PDAs cellular phones and smart phonesoPager is a oneway wireless messaging system it alerts the user when it receives an incoming messageoEmail Handhelds such as the BlackBerry have a small display screen and a keypad for typing short message Email Handhelds help to keep in touch with clients and the office oCell Phone use radio wave to provide twoway communication The cell phone communicates with radio antennas towers placed within adjacent geographic areas call cells Cellular technology nowadays provides high transmission speeds and richer features SMS 3G Video WWW has progressed through four stagesFirst generation 1GAnalog signals and low bandwidth Second generation 2GDigital Signals for voice communication Speed up to 10 Kbps 25 GDigital Signals for voice communication Speed up to 144 KbpsThird generation 3GDigital Signals for voice communication Speed up to 128 Kbps in car 384 Kbps walking and 2 Mbps fixed oPersonal Digital Assistants PDAs are small handheld computers that can transmit digital communications PDAs provide electronic schedulers address books emails service wireless internet access camera and voice communication some only oSmart Phones are a new class of digital communication appliances color screen and builtin keyboard that combine the functions of PDA and digital cell phone Smart phones 1provide organizer cell phone digital camera email internet access Short message service SMS photo music and video The smart camera phone can cause damage in workplace by easily send out company secretsThe major types of Wireless Transmission Media are Microwave Satellite Radio and Infrared 1Microwave transmission systems are widely used for highvolume longdistance pointtopoint communication Microwave towers usually cannot be spaced more than 30 miles apart earth surfaces not flat and affected by bad weather such as heavy rain or snowstorms Pointtopoint has two characteristics first the transmitter and receiver must be in view of each other called lineofsight and second the transmission itself must be tightly directed from transmitter to receiver2Satellite transmission systems make use of communication satellites three types of satellites each in a different orbit Geostationary earth orbit GEO orbits 22300 miles directly above the equator and maintains a fixed position excellent for TV signalsMediumearthorbit MEO are located 6000 miles above the earths surface and move used for GPS and are less expensiveLowearthorbit LEO are 400 to 700 miles above the surface and move much quicker so they require many to have adequate coverage use for telephoneFootprint is the area of earths surface reached by a satellites transmissionovercomes the limitations of microwave data relay stationsBroadcast transmission allows satellites to send signals to many receivers at one timePropagation delay is a brief pause in transmissions from GEO satellites which make twoway telephone conversations difficult GPS is a wireless system that uses satellites to enable users to determine their position anywhere on the earth supported by 24 shared satellites worldwide Internet over Satellite IOS allows users to access the Internet via GEO satellites from a dish mounted on the side of their homes But only option 2available in some areas and can have a propagation delay or be disrupted by environmental conditions3Radio transmission uses radiowave frequencies to send data directly between transmitters and receivers Satellite radio digital radio offers uninterrupted near CDquality music that is beamed to your radio from space XM satellite radio uses GEO Sirius uses MEO Advantages radio wave travel easily through normal walls devices are cheap and easy to install can transmit data at high speedDisadvantagesradio media can create electronic interference problems radio transmissions are affected by similar equipment that operate on the same frequency 4Infrared light is red light that is not commonly visible to human eyes common uses in remote control units for TVs VCRs DVDs CD players Infrared are also used for shortdistance connection between computer and peripheral equipment and LANWireless Computer Networks and Internet Access Advantages of Wireless networksoMobilityoNo line or cable connection neededoAccess more current dataoSmall equipment eg PDAAdvantages of Wireless networksoStraight line signals must be in rangeoNetwork incompatibilityoSlower transmission this is changingoSmall screenskeyboardsoLess memory on PDAsoHigh cost per minute although this is changingWireless manners Rules for using a wireless cafoLimit your timeoUse cell phone quietly headphones for musicoMinimize wall socket timeoPlace cables in a safe place ask permission to use extension cords oClean and noncontroversial surfingInstitute of Electrical and Electronics Engineers IEEE standards for wireless computer networks includeoIEEE 80215 Bluetooth for wireless personal area networks PANs and 802154 ZigbeeoIEEE 80211 WiFi for wireless local area networks WLANsoIEEE 80216 WiMax for wireless metropolitan area networks WMANsoIEEE 80220 proposed for wireless wide area networks WWANsstill under development Impact of multiple standards oDifficult to exchange wireless information from different standards eg BlueTooth to WiFi Cell phones to laptops3
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