transmission system of gsm

GSM is an acronym that stands for Global System for Mobile Communications. The basic architect of the GSM network comprises Base Transceiver Station (BTS), Base Station Controller (BSC), Mobile Switching Centre (MSC), Home Location Register (HLR), Visitor Location Register (VLR), Equipment-Identity Register (EIR), Network Management System (NMS) and Mobile Station (MS) which is made up of the mobile equipment and the Subscriber Identity Module (SIM).

GSM has defined several standard interfaces; the radio interface (Um), the interface between MSC and BSC (A interface) and the signaling interface, which allows roaming between networks. Roaming is a service unique to GSM which enables a subscriber to make and receive calls when outside the service   area of his home network e.g. when traveling abroad.

The BTS and the BSC together form the base station subsystem (BSS) and carry out all the functions related to the radio channel management. This includes the management of the radio channel configurations, allocating radio channel for speech, data and signaling purposes, and controlling frequency hopping and power control. The BSS also includes, as does the MS, the speech encoding and decoding and channel coding and decoding. Often base transceiver stations are positioned at regular intervals close to main roads in order to give communication service coverage to motorists. Each BTS comprises the radio frequency component and the antenna for communicating with the mobile stations. Usually, several base transceiver stations are under the control of a BSC which in turn communicates directly by a land line or a microwave link with an MSC. Several base station controllers may report to one MSC.

MSC, VLR and HLR are concerned with mobility management functions. These include authentication and registration of mobile customer, location updating and call set up and release. The HLR is the master subscriber database and carries information about individual subscribers, numbers, subscription levels, call restriction, supplementary services and the current location (or more recent locations) of subscribers. The VLR acts as a temporary subscriber database for all subscribers between its coverage areas and contains similar information to that in the HLR. The provision of VLR means that the MSC does not need to access the HLR for every transaction.

The Authentication Centre (AUC) works closely with the HLR and provides information to authenticate all calls in order to guide against fraud. The EIR is used for equipment security and validation of different types of mobile equipment.

Network management is used to monitor and control the major elements of the GSM network. In particular, it monitors and reports faults and performance data. It is also used to reconfigure the network. The network behind the GSM seen by the customer is large and complicated in order to provide all of the services which are required. The network is divided into subsystems:

1. The Base Station Subsystem(the base station and their controllers).
2. The network and switching Subsystem(the part of the network most similar to a fixed network). This sometimes also called the core network.
3. 3. The General Packet Radio Service (GPRS) Core Network(the optional part which allows packet based internet connections). All of the elements in the network combine to produce many GSM services such as voice calls and short message service(SMS).

Meaning of Internet and its Process

Internet is a computer-based worldwide information network. The internet is composed of a large number of smaller interconnected networks called Internets.

These Internets may connect tens, hundreds or thousands of computers, enabling them to share information with each other, these computers can be located several thousands of miles from each other.

The internet is based on the concept of a client-server relationship between computers as described above. The arrangement is also called client/server architecture. In a client server architecture, some computers act like server or information providers, while other computers act as clients or information receivers. A single client computer may access many different servers and a single server may be accessed by a number of different client computers. To access information on the internet, a user must first log in from a computer. Such a computer is called the client computer. The computer may be a desktop or a notebook, which may be located at home, in an office, in a school or at a business centre referred to nowadays as cybercafé.

The client computer must be linked to an Internet Service Provider (ISP). An ISP or access provider is a company that sells computer access to the internet. A user pays a fee to an ISP, which gives the user an identifying username and a password. An example of a username is [email protected]. This means that the username is Oluwunmis and is connected by an ISP called Skannet. The user specifies the password that he or she wishes to use. This is to prevent somebody else from using his account with the ISP. A password is therefore known to the user or to anybody authorized to use the account, the user must remember it always once it is typed into the ISP’s system, otherwise he or she will not be able to access the internet. The user will try as much as possible to guide and secure his password so that his account is not broken into by hackers for unauthorized access.

Internet Equipment and Transmission Process

With his or her computer and modem, the calls the telephone number of the ISP to log on to the service provider’s computer. The user’s computer then lets the service provider’s computer take over. Once a connection has been established, the user may request information from a remote server located anywhere in the world.

Typically, the request may be transmitted through a telephone line (a process referred as dial-up) or through a radio link to the internet service provider’s computer.

Merits of the Internet

1. It is used to send written messages between individuals or groups of individuals, often geographically separated by large distance.
2. It gives advertisers easy access to a large pool of consumers within a district, province, country, regional trading area  and the whole world at a low cost.
3. It gives consumers access to worldwide information on the product they wish to buy and pay for it through the internet.
4. It makes distance learning education possible. Students can attend classes irrespective of their location by logging on to the internet.
5. It allows one to have access to libraries and database.
6. It allows one to get headlines and in-depth stories on everything going on in the world.

Demerits of the Internet

1. It is used in defrauding innocent people of their money by transacting illegal business with them, this is known as cyber crime.
2. Intellectual property is stolen on the internet.
3. It gives easy access to pornographic pictures and increases their level of sexual immoralities.

ASSESSMENT

1. What does GSM stand for?
2. List 3 merits of the internet
3. List 3 demerits of the internet
4. Define Internet
5. What does GPRS stand for?