26-08-2014, 03:23 PM
Mobile Communications Principles
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Introduction
Each mobile uses a separate, temporary radio channel to talk to the cell site. The cell site talks to many mobiles at once, using one channel per mobile. Channels use a pair of frequencies for communication. One for transmitting from the cell site, the forward link, and one frequency for the cell site to receive calls from the users, the reverse link.
Communication between mobile units can be either half-duplex or full-duplex. In case of half-duplex, transmit and receive communications between the mobile units are not at the same time i.e. talking and listening cannot be done at the same time. In case of full-duplex communication, transmit and receive communication is at the same time, i.e. one can talk and listen at the same time.
When communications between mobile units are within a cell, and if the same is Traditional mobile service was structured similar to television broadcasting. One very powerful transmitter located at the highest spot in an area would broadcast in a radius of up to fifty half-duplex, then it shall require only one pair of frequency. If the same is full-duplex, then requirement of frequency pair shall be two. Kilometers. The “cellular concepts” structure the mobile telephone network in a different way. Instead of using one powerful transmitter, many low-power transmitters were placed throughout a coverage area. For example, by dividing a metropolitan region into one hundred different areas (cells) with low-power transmitters using twelve conversations (channels) each, the system capacity theoretically could be increased from twelve conversations - or voice channels using one powerful transmitter- to twelve hundred conversations(channels) using one hundred low-power transmitters.
Literature Survey
In the mid-1860s, the Scottish mathematician James Clerk Maxwell produced a pair of equations whose solution predicted electromagnetic waves propagating at the speed of light. It took 20 years to verify this prediction in the laboratory, and another 20 years for the first “mobile” application to take place. In September of 1899, Guglielmo Marconi ushered in the era of practical mobile radio communication with his historical radio telegraph transmissions from a ship in New York Harbor to the Twin Lights in Highlands New Jersey. His first transmission covered the arrival of Admiral Dewey from Manila, and soon thereafter, coverage of the Americas Cup races was provided as well. This was accomplished with high energy, wideband pulses of radio noise, created using a spark generator coupled to an antenna. The signal was received with a similar antenna attached to a fascinating device known as a “coherer,” a tube in which metallic particles were caused to cohere to one another by the presence of the radio signal. The reduced resistance of the coherer in this state allowed the radio signal to be detected, after which a mechanical “tapper” returned the particles to their original state. Each telegraphic symbol was represented by a rapid series of these spark-generated signals, which was detected as an audible tone. [1]
Mobile Radio
The mobile radio is a two-way communication gadget that operates through radio frequencies. As such, the channel of information and messages in a mobile radio is variable. Used to be known as radiophone, the earlier versions of the mobile radio, were one-way communication systems used for broadcast.
Contemporary mobile radio systems can have as much as a hundred channels and may be controlled by microprocessors. These types require the use of software to encode channels and operate their integrated functions. The mobile radio, also known as a two-way radio system, allows the exchange of messages only with other mobile radios through push-to-talk (PTT) functions. A mobile radio also features wireless transceivers, making mobile radios portable. Mobile radio systems may be used for communications in aircraft, ships, automobiles, and other vehicles. The power supply on which mobile radios run depend on the type of vehicle these are mounted on.
A mobile radio system is composed of a transceiver and microphone with a push-to-talk key. It has an antenna that links to the transceiver. Since most types of mobile radio are used in moving vehicles, where the surrounding noise can be loud, some mobile radio types come with an external speaker. Other models have headsets and microphones with noise-reduction capabilities.
GSM System
The GSM (Global System for Mobile Communication) MoU Association, a Swiss registered Corporation, is the principle body responsible for promoting and evolving the GSM wireless platform worldwide. Today GSM is the most successful implementation of a global wireless standard using digital technology for point to point operations. There are over 293 members representing 120 countries/areas. The overall objective of the GSM MoU Association is “ The promotion and evolution of the GSM900, GSM1800, GSM1900 systems, and the GSM platform for international roaming, for the provision of standardized services.
Advantages
* A universal medium Can be enjoyed at home, at work, and while driving. Most people listen to the radio at one time or another during the day.
* Permits you to target your advertising dollars to the market most likely to respond to your offer.
* Permits you to create a personality for your business using only sounds and voices.
* Free creative help is usually available.
* Rates can generally be negotiated.
* Least inflated medium. During the past ten years, radio rates have gone up less thanothermedia.
Disadvantages
* because radio listeners are spread over many stations, to totally saturate your market you have to advertise simultaneously on many stations.
* Listeners cannot refer back to your ads to go over important points.
* Ads are an interruption to the entertainment. Because of this, radio ads must be repeated to break through the listener's "tune out" factor.
* Radio is a background medium. Most listeners are doing something else while listening, which means your ad has to work hard to be listened to and understood.
* Advertising costs are based on ratings which are approximations based on diaries kept in a relatively small fraction of a region's homes.
* Not as fast as using a phone; could take a little bit
* the line could get fuzzy, or not clear
Chapter4. Conclusion and future scope
Mobile Communication today is a fast growing field. No one can deny its role in Modern Railway Operations. However there is a need of proper choice of technology looking into Railways' Operational needs. It is beyond doubt that incorporation of Mobile Communication into Railways will open new operational avenues, thereby reducing operational costs and increasing customer satisfaction by providing better services. This shall not only help in increasing productivity, but also help in increasing safety of operations. This is an age of communication. Indian Railways, which is a lifeline of the nation, is also geared up to take the requirements of the new millennium, which is knocking the door of this century.
[attachment=67070]
Introduction
Each mobile uses a separate, temporary radio channel to talk to the cell site. The cell site talks to many mobiles at once, using one channel per mobile. Channels use a pair of frequencies for communication. One for transmitting from the cell site, the forward link, and one frequency for the cell site to receive calls from the users, the reverse link.
Communication between mobile units can be either half-duplex or full-duplex. In case of half-duplex, transmit and receive communications between the mobile units are not at the same time i.e. talking and listening cannot be done at the same time. In case of full-duplex communication, transmit and receive communication is at the same time, i.e. one can talk and listen at the same time.
When communications between mobile units are within a cell, and if the same is Traditional mobile service was structured similar to television broadcasting. One very powerful transmitter located at the highest spot in an area would broadcast in a radius of up to fifty half-duplex, then it shall require only one pair of frequency. If the same is full-duplex, then requirement of frequency pair shall be two. Kilometers. The “cellular concepts” structure the mobile telephone network in a different way. Instead of using one powerful transmitter, many low-power transmitters were placed throughout a coverage area. For example, by dividing a metropolitan region into one hundred different areas (cells) with low-power transmitters using twelve conversations (channels) each, the system capacity theoretically could be increased from twelve conversations - or voice channels using one powerful transmitter- to twelve hundred conversations(channels) using one hundred low-power transmitters.
Literature Survey
In the mid-1860s, the Scottish mathematician James Clerk Maxwell produced a pair of equations whose solution predicted electromagnetic waves propagating at the speed of light. It took 20 years to verify this prediction in the laboratory, and another 20 years for the first “mobile” application to take place. In September of 1899, Guglielmo Marconi ushered in the era of practical mobile radio communication with his historical radio telegraph transmissions from a ship in New York Harbor to the Twin Lights in Highlands New Jersey. His first transmission covered the arrival of Admiral Dewey from Manila, and soon thereafter, coverage of the Americas Cup races was provided as well. This was accomplished with high energy, wideband pulses of radio noise, created using a spark generator coupled to an antenna. The signal was received with a similar antenna attached to a fascinating device known as a “coherer,” a tube in which metallic particles were caused to cohere to one another by the presence of the radio signal. The reduced resistance of the coherer in this state allowed the radio signal to be detected, after which a mechanical “tapper” returned the particles to their original state. Each telegraphic symbol was represented by a rapid series of these spark-generated signals, which was detected as an audible tone. [1]
Mobile Radio
The mobile radio is a two-way communication gadget that operates through radio frequencies. As such, the channel of information and messages in a mobile radio is variable. Used to be known as radiophone, the earlier versions of the mobile radio, were one-way communication systems used for broadcast.
Contemporary mobile radio systems can have as much as a hundred channels and may be controlled by microprocessors. These types require the use of software to encode channels and operate their integrated functions. The mobile radio, also known as a two-way radio system, allows the exchange of messages only with other mobile radios through push-to-talk (PTT) functions. A mobile radio also features wireless transceivers, making mobile radios portable. Mobile radio systems may be used for communications in aircraft, ships, automobiles, and other vehicles. The power supply on which mobile radios run depend on the type of vehicle these are mounted on.
A mobile radio system is composed of a transceiver and microphone with a push-to-talk key. It has an antenna that links to the transceiver. Since most types of mobile radio are used in moving vehicles, where the surrounding noise can be loud, some mobile radio types come with an external speaker. Other models have headsets and microphones with noise-reduction capabilities.
GSM System
The GSM (Global System for Mobile Communication) MoU Association, a Swiss registered Corporation, is the principle body responsible for promoting and evolving the GSM wireless platform worldwide. Today GSM is the most successful implementation of a global wireless standard using digital technology for point to point operations. There are over 293 members representing 120 countries/areas. The overall objective of the GSM MoU Association is “ The promotion and evolution of the GSM900, GSM1800, GSM1900 systems, and the GSM platform for international roaming, for the provision of standardized services.
Advantages
* A universal medium Can be enjoyed at home, at work, and while driving. Most people listen to the radio at one time or another during the day.
* Permits you to target your advertising dollars to the market most likely to respond to your offer.
* Permits you to create a personality for your business using only sounds and voices.
* Free creative help is usually available.
* Rates can generally be negotiated.
* Least inflated medium. During the past ten years, radio rates have gone up less thanothermedia.
Disadvantages
* because radio listeners are spread over many stations, to totally saturate your market you have to advertise simultaneously on many stations.
* Listeners cannot refer back to your ads to go over important points.
* Ads are an interruption to the entertainment. Because of this, radio ads must be repeated to break through the listener's "tune out" factor.
* Radio is a background medium. Most listeners are doing something else while listening, which means your ad has to work hard to be listened to and understood.
* Advertising costs are based on ratings which are approximations based on diaries kept in a relatively small fraction of a region's homes.
* Not as fast as using a phone; could take a little bit
* the line could get fuzzy, or not clear
Chapter4. Conclusion and future scope
Mobile Communication today is a fast growing field. No one can deny its role in Modern Railway Operations. However there is a need of proper choice of technology looking into Railways' Operational needs. It is beyond doubt that incorporation of Mobile Communication into Railways will open new operational avenues, thereby reducing operational costs and increasing customer satisfaction by providing better services. This shall not only help in increasing productivity, but also help in increasing safety of operations. This is an age of communication. Indian Railways, which is a lifeline of the nation, is also geared up to take the requirements of the new millennium, which is knocking the door of this century.