CELLULAR NETWORK

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Cellular Network:

Cellular Network Muhammad Usman Tahir

Basic Concept:

Basic Concept Cellular system developed to provide mobile telephony: telephone access “anytime, anywhere.” First mobile telephone system was developed and inaugurated in the U.S. in 1945 in St. Louis, MO. This was a simplified version of the system used today.

An Important Technology:

An Important Technology Cellular telephony is one of the fastest growing technologies on the planet. Presently, we are starting to see the third generation of the cellular phones coming to the market. New phones allow users to do much more than hold phone conversations.

Cell Phone = Radio?:

Cell Phone = Radio? Combination of telephone and radio ideas First mobile communications: “radio telephone” Requires powerful transmitter; minimal channels

System Architecture:

System Architecture A base station provides coverage (communication capabilities) to users on mobile phones within its coverage area. Users outside the coverage area receive/transmit signals with too low amplitude for reliable communications. Users within the coverage area transmit and receive signals from the base station. The base station itself is connected to the wired telephone network.

First Mobile Telephone System:

First Mobile Telephone System One and only one high power base station with which all users communicate. Entire Coverage Area Normal Telephone System Wired connection

Cellular Concept:

Cellular Concept Thus, instead of one base station covering an entire city, the city was broken up into cells , or smaller coverage areas. Each of these smaller coverage areas had its own lower-power base station. User phones in one cell communicate with the base station in that cell.

Complete Cellular Network:

Complete Cellular Network A group of local base stations are connected (by wires) to a mobile switching center (MSC). MSC is connected to the rest of the world (normal telephone system). MSC MSC MSC MSC Public (Wired) Telephone Network

Circular Coverage Areas:

Circular Coverage Areas Original cellular system was developed assuming base station antennas are omnidirectional , i.e., they transmit in all directions equally. Users located outside some distance to the base station receive weak signals. Result: base station has circular coverage area. Weak signal Strong signal

Mobile Switching Centers:

Mobile Switching Centers Mobile switching centers control and coordinate the cellular network. They serve as intermediary between base stations that may be handing off users between each other. Base stations communicate with each via the MSC. MSC keep track of cell phone user subscription. MSC connects to the wired phone network (rest of the world).

The Core Idea: Cellular Concept:

The Core Idea: Cellular Concept The core idea that led to today’s system was the cellular concept. The cellular concept : multiple lower-power base stations that service mobile users within their coverage area and handoff users to neighboring base stations as users move. Together base stations tessellate the system coverage area.

Cell phone towers:

Cell phone towers

Contd.....:

Contd..... The box houses the radio transmitters and receivers that let the tower communicate with phones. The radios connects with the antennae on the tower through thick cables.

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