Classification of Mobile Communication Systems

Mobile radio communication means any radio communication between two terminals of which one or both are in motion. Mobile radio communication systems can be classified as follows:

(a)        Radio Phones (or walkie-talkies): These are two-way radios such as citizen band radios which are allocated channels for anyone to use whenever the channels are free. This system affords no privacy to the user.

(b)        Dispatching communication system: These use a common channel. Any vehicle driver can hear the operators messages to others driver in the same fleet. Here the drivers can talk only to the control operator. In other-words, the drivers cannot talk to other drivers in the fleet.

(c)         Radio paging systems: Here customer carries personal receivers. Each unit reacts only to signals addressed to it by an operator. Usually a beep sounds to alert the bearer who then will go to a near by public telephone to receive a massage.

(d)        Packet radio systems: These use a form of multiple access control that permits many scattered device to transmit on the same radio channel without interfering on each others transmission. Here, the data to be transmitted are formed into a packet within the transmission control unit. The packet contains the addresses of the receiving location and the originating terminal.

(e)        Cellular communication systems: These are for high capacity voice and data transmission. It includes the GSM and the personal communication services (PCS). The PCS is a cellular like system applied at 1.8 – 1.9 GHz instead of the 800- 900 MHz for GSM.