Cellular or the mobile telephones were the pioneer in the field of mobile telecommunications in the world as a whole. Mobile telecommunication devices like mobile phones are movable telecommunication device unit. mobile telecommunications allows people to communicate over a wide area by using a grouping of radio, telecommunication device, and computer technology.
GSM (Global System for Mobile Communications) is the second generation of mobile communications. The first generation was analog telephony.
GSM stands for Global System for Mobile communications. In countries that use GSM 900 MHz and 1800 MHZ, cell phone users can buy one phone that will work wherever the standard is supported Global System for Mobile Communications introduced the concept of SIM (Subscriber Identity Module) card, which stores the subscription information, the operator's information, and had some memory for the user to store text messages and phone book. One can easily switch between the operators by changing the SIM cards. GSM in the world operates on 3 bands, 900 Mhz, 1800 Mhz and 1900 Mhz. At present, there are hundreds of functional Global System for Mobile Communications networks in an equally large number of countries, and the acronym now aptly stands for Global System for Mobile telecommunications.
CDMA (Code Division Multiple Access) employs analog-to-digital conversion (ADC) in which audio input is first digitized into binary elements. In CDMA, all callers occupy the same frequency band with the voice signals converted into counterfeit random code. This code is used again at the receiving end to recover the original signals. Code Division Multiple Access allows the use of a single transmission channel by several subscribers simultaneously. Consequently, the available bandwidth can be used more effectively. In Code Division Multiple Access, data packets are transported over the digital transmission route, together with an encoded address for each receiver.
The capacity of Code Division Multiple Access network is about four to five times as much as that of a GSM network. Code Division Multiple Access based stations cover a larger geographical area. It offers better coverage, better call quality and practically indestructible privacy. Because all the calls on a CDMAnetwork make use of the same frequency band, there is no requirement of frequency planning in a CDMA network. So it can be easily understood that Code Division Multiple Access is the technology of the future of mobile telecommunication.
A mobile telecommunication system consists of three main parts:
When a call is made on a mobile telecommunication device, radio waves carry the message to an aerial transmitter. This aerial is centrally located in a geographical area called a cell. Cells vary in size and number, according to the area of thenetwork . The transmitter sends the message to a computerized central switching office. The central switching office transmits the message to a local or long-distance mobile telecommunication provider company, where the call is sent to its destination. As a caller moves across a service area, the call is automatically passed from one transmitter to another without interruption of operation.
The mobile telecommunications industry is one of the most rapidly growing sectors in the United States of America. During the last decade, the industry as a whole has jumped from a premium service industry for mostly professional users to a truly mass market. Unlike most other countries, the United States never nationalized its mobile telecommunications industry. American Telephone and Telegraph Co. (AT&T) came out as the chief commercial strength in developing mobile services and networks in the early years later followed by companies like T mobile and Cingular Wireless.
The U.S. mobile sector is among the most aggressive and least intensed in the world. More than 229 million Americans live in areas where they have access to at least five competing mobile service providers, and 151 million-more than half the populations-live in areas with six different competitors. In 2002, there were six mobile telephony providers that are believed as nationwide carriers, because they manage licenses in many areas across the nation. Those are AT&T Wireless, Sprint PCS, Verizon Wireless, VoiceStream, Cingular Wireless, and Nextel. During the last seven years, the subscriber base in US mobile telecommunication market has jumped to approximately 200 millions from 110 millions But industry sources indicate that minutes of use increased anywhere from 22% to 51% during the period.