text to use in the project

TELECOMMUNICATIONS 1. DEFINITIONS Telecommunications: Refers to any procedure that allows a user to get to one or more specific users (eg telephony) or possible (eg radio, television), information of any nature (written, printed, still or moving image , video, voice, music, signs visible, audible signals, signals of mechanical controls, etc..), using this procedure, any electromagnetic system for transmission and / or reception (electrical transmission by wire, radio, optical, or a combination of these various systems) Telecommunications System: The set of equipment and links to both physical and electromagnetic usable for the provision of a telecommunications service. Telecommunications Service: Is the activity conducted under the responsibility of a particular company or organization to provide its users with a form or type of telecommunications, the use is of interest to that user. Public Telecommunications Service: This is one service that is provided generally to all residents of a country, responsible for providing the state, but it can give as concessions to private companies, but always regulate. 1.2. CLASSIFICATION BY MEANS OF PROPAGATION a. b. Terrestrial Telecommunications: Are those which are spread through physical lines, these can be copper wire, coaxial cable, waveguide, fiber optic, twisted pair, etc.. c. Telecommunications Radio: Are those who use as a means of spreading the Earth's atmosphere, transmitting signals in electromagnetic waves, radio waves, microwaves, etc.. depending on the frequency at which it is transmitted. d. Satellite Telecommunications: Are those radio communications that take place between space stations, space between earth stations, between earth stations (via relay in a space station). Space stations are located at different heights out of the atmosphere. 2. CELLULAR TELEPHONES 2.1. DEFINITIONS Mobile Telephony: Is this phone in which the coverage area is divided into cells and sectors. The means of Tx / Rx between the subscriber and exchange is wireless, via radio frequency channels. Mobile Cellular Telephony: Is that cell phone in which the subscriber's terminal can move from one place to another (maintaining an established communication) with a speed of up to 200 km / h. Cell Phones & Low Mobility: Is that cell phone in which the terminal can move but at a low speed (low mobility), ages 10 to 40 km / h. It is actually a wireless local loop system, but has mobility through an algorithm to compensate for delay time, and uses the same type of telephone equipment for mobile phones, but with access time (TDD). Wireless Local Loop (WLL): Allows you to provide fixed telephone service, also under the criteria of cellular telephony, but the terminal does not have mobility. The path from the PBX to the subscriber (local loop) is by wireless means (wireless). When the voice is packetized called WLL-IP Fixed Wireless Access (FWA): The stretch between the subscriber (fixed) and base station, using the means of transmission spectrum. You can pass any services such as telephony, internet, broad band, and so on. Personal Communications System (PCS): This is one that provides universal access to services such as voice, data, video, audio, messaging, positioning, Internet, etc.., Wirelessly to mobile users. Is commonly associated with mobile phone. 2.2. BASIC STRUCTURE OF A CELL A cellular system consists of four elements: • mobile phone terminal • Base Station • Control station and switching • Radio channels • CELLULAR MOBILE TERMINAL It is the electronic equipment that allows a subscriber to make or receive calls, is composed of: control unit, power supply, transmitter / receiver, antenna. It is portable, transportable, movable from one place to another. Make a regular update on the signal received from the base station sends information to register for the base station. • Base Station (BTS) • It is the central station within a cell, known as BTS (Base Tranceiver Station), performs the RF link to cellular terminals, transmits information between the cell and the control and switching station, monitors the communication of subscribers. This consists of: control unit, power unit, sectorial antennas (using diverse methods to capture the best signal), TRAU (unit responsible for adapting and conversion of code and speed of signals), and data terminal . • CONTROL AND SWITCHING STATION Commonly known as MTSO (mobile telephony switching office), when applied technology called GSM MSC (Mobile Switching Center) and Wireless Local Loop network called XBS. It is the central element of the system, its main functions are: • Coordinates and manages all BTS • Coordinate office calls between fixed and subscribers, as well as calls between mobile terminals and subscribers via the BTS • Responsible for the billing (billing) • Manages the Hand-off between cell site • Has a Sotfware management: network management system • • The central TANDEM interconnects to communicate with other telephone networks. It may be of 2 types (according to geographical area and amount of traffic): • Centralized: a single center for the entire concession area operator, using star topology,. • Decentralization: a more central, distributed in the concession area. • ( ') The BTS, Central and TANDEM are interconnected via optical fiber links, or via microwave (link high speed data - SDH). • RADIO CHANNELS • Radio Canal means the pair of carrier frequencies over a time slot, which will serve as channels of communication traffic. Of these 2 frequencies one will be the frequency of base station Tx and Rx of the terminal, the other frequency will be that of the base station Rx and Tx terminal. Carry voice and data between subscriber and base stations, each subscriber can only use one channel at a time. 2.3. TYPES OF RADIO CHANNELS The cellular channels or radio channels are those that will allow cell phone communication. They can be of 2 types: a) Control Channel (CCH): This channel can send and receive data between the BTS and the laptop. These channels include: • Advance Control Channel (FCC) generally provides basic information about the particular cell system: system identification number, range of paging channels and access that can scan. • Paging Channel: These are the channels used to keep temporary location to a terminal. • Channel Access: There are channels used to reply when the terminal is being called, or to initiate a call. It is also used to inform the TCH laptop to use. • In small areas of low traffic, a single control channel performs the tasks of the three channels. b) Traffic Channel (TCH): Also known as voice channels, is responsible for driving traffic (voice and data) between the base station and the laptop when in the process of call. It is also used for signaling messages sent by the BTS to the laptop, also to handle the hand over process, and transmit power control terminal. Data from the BTS are called "data in advance" and from the terminal are called "reverse data", both are sent to 10 Kbps REFERENCES Bellamy, John. (1996). "DIGITAL TELEPHONY" Wiley, 1st edition, New York. Lati, Robert. (1986). "Communication system". Mc Graw-Hill, 1st edition, Mexico. Praxis (1994). "COMMUNICATION SYSTEMS ENGINEERING". Prentice-Hall, 1st edition, New Jersey. Mendiburu Henry Diaz Electronic Engineer