Global System for Mobile Communications (previously Special Mobile Group) is a digital standard for second-generation mobile telephony. The working group of the set was established in 1982 by the Conference of Postal and Telecommunications Administrations.
It has been specified and developed by ETSI for the frequency range of 900 MHz. A variant called Digital Communication System (DCS) uses the 1800 MHz range. This standard is used particularly in Europe, Africa, the Middle East and Asia. Two other variants, in 850 MHz and 1900 MHz (PCS), are also used. Data protection is ensured by the algorithms A5/1 encryption and A5/2.
As it was designed, the GSM network is ideal for communications such as voice. The network management is switched, the resources are allocated for the duration of the conversation, as in the use of fixed telephone lines. Customers can either buy a prepaid card or a subscription.
Under the auspices of the organization 3GPP GSM standard was later extended to support higher data rates and data transport mode package by the GPRS (General Packet Radio Services) and EDGE extensions (Enhanced Data rates for GSM Evolution). These two modes can coexist with the “switched voice” of the GSM mode and use the same antenna and the same frequency bands that form part of Network Configuration and Change Management.
The methods of using the Internet differ depending on the type of service you require and the type of server to which you connect, to name just a few. Electronic mail (e-mail) allows you to send and receive (to / from users) messages containing text and other formats (eg, images, video, audio). The mode of operation of the e-mail server and many client programs is called store-and-forward.
File Transfer Protocol (FTP) allows you to send and receive (to/from systems) file, that is, sets of information encoded in a binary (eg text, images, videos, programs, etc.). Hyper Text Transfer Protocol (HTTP) allows you to organize information and resources on the network in a non-sequential (Hyperlink). Founded as a data communications network between users later became also a network to transfer voice data through the development of VOIP technology.
DBMS software may be distributed across multiple sites connected by a network. There are two types: Distributed homogeneous DBMS: use the same DBMS at multiple sites and distributed heterogeneous DBMS: gives rise to federated data systems multibase DBMS where participants have some degree of local autonomy and have access to several existing independent databases stored in DBMS, many of these employ a client-server architecture.
These arise due to the physical existence of decentralized organizations. This gives them the ability to link databases of each location and gain access to various universities, branches of stores, etc.