Mobile phones
Mobile phones provides us various purposes such as communication,surfing internet,messaging,gaming and various other application's.
Influence of mobile phones on human life
Today mobile phones has became one of the important factor in human life.We cannot even assume a life without mobile phones.Because the mobile technology has advanced so far.Many applications have been installed to the mobile phones for the easy access of user's.Now a day's mobile phones are available according to our various needs.From this we can understand the influence of mobile phones having over human beings.So how could be this possible?To understand this we have to learn more about mobile communication.
Mobile phones had an tremendous growth in the field of telecommunication.In the earlie's there were only land telephones.There were lots of merits and as well as demerit's.The most among them was the portability of land phones were difficult.To overcome such difficulties we had invented wireless phones or mobile phones.Mobile phones have lot of advantages comparing to land phones.We had already said that development in technology had helped mobile phones in their growth.But there are another important factors which are to be considered in the case of mobile phones.Integrated circuits and increased battery life also played apart in it.According to the changing needs of users,the mobile phone companies have to make newer mobile series day by day.Users expect improved quality of services from mobile phones and their companies.There are different types of cellular system available today.They can be classified into three.They are First generation,Second generation and also the Third generation. Introduction & growth of mobile phones
In First generation analog system is a part of it.AMPS(advanced mobile phone systems) and TACS(total access communication system)also includes in analog system.AMPS was developed by USA in 1979 and TACS was by UK.Second generation consists of digital systems ,that is DAMPS(digital amps) and GSM(global system for mobile communication).DAMPS was developed by USA and GSM was developed fully by EUROPE IN 1990.Third generation comes with a global roaming .It consist of IMT2000(international mobile telecommunication)and UMTS(universal mobile telecommunication systems).IMT2000 was contributed by USA and UMTS of EUROPE.
These inventions are the contributions of different countries.That is ,they are forced to make appliances upon to meet and satisfy their customer needs such as frequency availability,subscriber density,different geographical conditions.In INDIA GSM was introduced in 1991 at a bandwidth of 900MHz.The reason for operating GSM in 900MHZ is that ,it uses 890MHz-950MHz for uplinking to the base station and 935MHz-960MHz for downlinking to mobile phones.It means that,for a one direction communication in GSM requires a bandwidth of 25MHz frequency and also available in now a days.
Mentioning about cellular concept,it is important to mention about the developers and introducers.It was introduced by the famous laboratories in the early's of 1970 called BELL laboratories.The basic principle of cellular system is explained below.In a cellular system,cells of having diameters from 2to50km are created by dividing a large geographic area.These cells are allocated with a number of RF channels.Many types of interferences may occur while using mobile phones.To avoid this problems transmitters are provided in adjacent cells which will operate on different frequencies.The important point is that in cellular communication,it uses frequency spectrum constraint which overcome-increasing demand.This problem is solved by using the concept of frequency reuse,cell splitting and multiple access techniques.
Frequency reuse can overcome many problems which we are facing through one communication.In this,it consist of cells which are formed by dividing service area into regions such as small of 1km or upto 35km radius.We can assume that these cells occupy a shape of hexagonal but in actual they are not.These hexagonal shaped cells can be grouped into clusters of 7,12or19 to form a type.To avoid interferences,each cell is allotted with different frequencies.In different geographic locations cells may use the same frequency channel.This is called frequency reuse and the distance of cells having same frequency which will create no interference between them.There are many factors on which the distance depends on transmitted power at each cell site,no of channels,types of geographic terrain and antenna height.
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