1.0 IntroductionA computer network is a system of interconnected computers and peripheraldevices. For example, it may connect computers, printers, scanners andcameras. Using hardware and software, these interconnected computing devices cancommunicate with each other through defined rules of data communications.In anetwork, computers can exchange and share information and resources. A computernetwork may operateon wiredconnectionsor wirelessconnections. Whentwo ormorenetworks arelinkedor connectedandareabletocommunicatewithoneanother using suitable hardware and software, it is called an internet work.eanwhile, communications is about thetransfer of informationfromasender,across a distance, to a receiver. Using electricity, radio waves or light, informationand data in the form of codes are transmitted through a physical medium such aswire, cable, oreventheatmosphere.!herefore, inordertomakecommunicationspossible from computers, across telephones and radios and back to computers andother digital devicesagain, theremust beasignal translator, whichwecall "amodem. !he modem, which is short for modulator or demodulator, converts digitalsignals into analog and back again into digital signals for information to move acrossthe telephone line.#2.0 Mobile Computing2.1 Definitionobile computing is human computer interaction by whicha computer is expected to be transported during normal usage. obile computinginvolves mobile communication, mobile hardware, and mobile software.$ommunicationissues include adhoc andinfrastructure networks as well ascommunication properties, protocols, data formats and concrete technologies.%ardwareincludes mobiledevices or devicecomponents. obilesoftware dealswith the characteristics and re&uirements of mobile applications.2.2 Specification and frequences of Mobile Computing2.2.1 Specification'( 'lobal (ystem for obile$)A $ode )ivision ultiple Access%(*A %igh (peed *acket Access+,)- +volution.)ata -ptimi/ed0!+ 0ong.!erm +volution12.2.2 Servicesessaging.iessage.((.(.+mail.*ush +mailWeb 2rowser .%!03 4(afari56ava.i$loud $loud.!,.-ut.aps.-rgani/er.,oice memo.i!unes2.2.3 Frequencies.'( 7389:889#7889#:88.%()*A 7389:889#;889#:8891#883.0 Internet ec!nolog" and Services3.1 #oI$,oice.over.Internet *rotocol 4,oI*5 is a methodology and group oftechnologies for the delivery of voice communications and multimedia sessions