Mobile Telephone System
Mobile telephone system is used for wide area voice and data communication. Cell phones have gone through three different generations, called 1G, 2G and 3G. The generations are as following:
1. Analog voice 2. Digital voice 3. Digital voice and data
These are explained as following below.
- First generation (1G) Mobile Phones : Analog Voice
1G system used a single large transmitter and had a single channel, used for both receiving and sending. If a user wants to talk then he has to push the button that enabled the transmitter and disabled the receiver. Such systems were called push-to-talk systems, and they were installed in the late 1950’s. In 1960’s IMTS (Improved Mobile Telephone System) was installed. It also used a high-powered (20-watt) transmitter on top of a hill but it had two frequencies, one for sending and one for receiving, so push to talk button was no longer needed.
- Second generation (2G) Mobile phones : Digital voice
The first generation mobile phones was analog though second generation is digital. It enables new services such as text messaging. There was no worldwide standardization during second generation. Several different systems were developed and three have been deployed. GSM (Global System for Mobile Communications). It is the dominant 2G system.
- Third generation (3G) Mobile Phones : Digital Voice and Data
The first generation was analog voice and second generation was digital voice but 3rd generation is about digital voice and data. 3G mobile telephony is all about providing enough wireless bandwidth to keep future users happy. Apple’s iPhone is the kind of 3G device but actually it is not using exactly 3G , they used enhanced 2G network i.e. 2.5G and there is not enough data capacity to keep users happy.
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