CELLULAR COMMUNICATION

Presented By: Guided By: Taushif. G. Sheikh Prof .V.S. Rahangdale

INTRODUTION TO CELLULAR COMMUNICATIONS:

1) MOBILE COMMUNICATIONS PRINCIPLES.

2) EARLY MOBILE TELEPHONE SYSTEM ARCHITECTURE.

3)THEORY OF OPERATION.

4)MOBILE TELEPHONE USING THE CELLULAR CONCEPT.

5) CELLULAR SYSTEM & ARCHITECTURE.

6)CELLULAR SYSTEM COMPONENTS.

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INTRODUCTION TO CELLULAR COMMUNICATION:

1)Cellular Communication is a type of mobile communication Cellular phone is a wireless communication just like cordless phone. A cell is the basic geographic unit of cellular system.

2) In cell phone the distance is not restricted to within home but one can travel in the city or even outside the city without interruption in communication.

2)The demand for cellular mobile phone is increasing at alarming level and is likely that wired communication will be replaced by wireless technology.

1)Each mobile uses a separate , temporary radio channel to talk to the cell site. The site talks to many mobiles at once , using one channel per mobile.

2)channels use a pair of frequencies for communication one frequency the forward link for transmitting from the cell site and one frequency the reverse link for the cell site to receive calls from the users .

3)Radio energy dissipates over distance, so mobile must stay near the base to maintain communications.

MOBILE COMMUNICATION PRINCIPLES:-

Early Mobile Telephone System Architecture:-

1)Traditional mobile services 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 kilometers.

2)The cellular concept structured the mobile telephone network using one powerful transmitter, many low power transmitters were placed throughout a coverage area.

3)By dividing a metropolitan region into one hundred different areas cells with low power transmitters.

* For Cellular Communication the frequency spectrum ranging from 825 to 845MHz and 870 to 890MHz.Full-duplex operation is possible by separating transmit and receive signals into separate frequency bands.

* Cellular phone units transmit in the lower band of frequencies, 825 to 845 MHz and receive in higher band, 870 to 890MHz.The opposite frequencies bands are used by the base units at the cells sites.

* Within these two bands,666 separate channels(333 channels per band) have been assigned for voice control. Each channels occupies a bandwidth of 30KHz.

Mobile telephone system using the cellular concept :

1)The ratio of the distance between areas to the transmitter power (radius ) of the areas by reducing the radius of an area by 50% System based on areas with 1KM radius would have 100 times more Channels than system with areas 10 KM in radius.

2)The cellular radio equipment base station can communicate with mobiles as long as they are within range . The Base station communicates with mobile via a channel. The channel is made of two frequencies, one for transmitting to the base station and one to receive information from the base station.

Cellular System Architecture:

1)In modern cellular telephony, rural and urban regions are divided into areas according to specifying provisioning guidelines.

2)Deployment parameters, such as amount of cell-splitting and cell size, are determined by engineers experienced in cellular system & architecture.

3) Provisioning for each region is planned according to an engineering plan that includes cells, clusters, frequency reuse, and handovers.

ClustersClusters:-A cluster is a group of cells. No channels are reused within a cluster.The given fig. illustrate a seven-cell cluster.

Cells:-

1)In cellular system city is divided into small areas called “cells” & each cell is around 10 square km (depends upon the power base station). The cells are normally thought of hexagons. Because cell phones & base stations use low power transmitter.

2)Each cell is linked to central location called the Mobile Telephone Switching Office (MTSO). The cell just encompasses only few square km area to communicate with cellular telephones.

Frequency Reuse:-

1)Only small number of radio channel frequencies were available for mobile systems. The concept of frequency reuse is based on assigning to each cell a group of radio channels used within a small geographic area.

2)Cells are assigned a group of channels that is completely different from neighboring cells. The coverage area of cells are called the footprint .

3)Cells with the same number have the same set of frequencies .The frequency reuse factor is 1/7.That is, each cell is using 1/7 of available cellular channels.

Cellular System Components:-1)The cellular system offers mobile and portable telephone stations the same service provided fixed stations over conventional wired loops. It has the capacity to serve tens of thousands of subscribers in a major metropolitan area.

2)The cellular communication system consists of the following four major components that work together to provide mobile service to subscribers.

1. Public Switched Telephone Network (PSTN).2. Mobile Telephone Switching Office (MTSO).3. Cell Site With Antenna System.4. Mobile Subscriber Unit(MSU).

PSTN:-The PSTN is made up of local networks, the exchange area net works, and the long-haul networks that interconnect telephones and other communication device on a worldwide basis.

Mobile Telephone Switching Office(MTSO):-The MTSO is the central office for mobile switching. It houses the Mobile Switching Center (MSC), field monitoring and relay stations for switching calls from cells sites to wire line central officers(PSTN).

The Cell Site:- The Cell site is used to refer to the physical location of radio equipment that provides coverage within a cell. A list of hardware located at a cell site includes power sources, interface equipment, radio frequency transmitters and receivers, and antenna systems.

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