Posted by: admin : Category: Global System for Mobile communications (GSM) is a technology standard that is used specifically for mobile communication. It is used in the digital transmission of voice and data. Around 80% of the world’s mobiles use the GSM standard. It was created by the European Conference of Postal and Telecommunications Administrations (CEPT), primarily for usage in Europe. Finland was the first country in Europe to implement and deploy GSM based mobile services.
Today GSM is the de facto mobile communications standard used across the world. It is so prevalent that users can travel across the world and use their existing mobile services as most GSM network operators have roaming agreements with overseas service providers. In fact, most SIM (Subscriber Identity Module) cards are configured to work with local access in other countries and that greatly decreases roaming costs.
The GSM Network
The GSM network consists of a number of components that work together to provide various mobile services to end-users. The components of a GSM network are as follows:
- Base Station Subsystem
- Network and Switching Subsystem
- GPRS Core Network (Internet connection)
The base station subsystem handles the traffic and signaling between a mobile phones and the network switching subsystem. The network switching subsystem takes care of the switching operations and controls the communications between mobile phones and the Public Switched Telephone Network (PSTN). It permits mobile phones to communicate with each other, and other telephones. The General Packet Radio service (GPRS) core network forms part of the GPRS system that is used by mobile phones, to transmit IP packets.
GSM Frequency Bands
GSM frequency bands are the cellular frequencies allocated by the International Telecommunications Union (ITU) for the deployment of GSM.
GSM-900 and GSM-1800 are utilized in most countries across the world. A majority of the Countries in Europe, Africa, Middle East and Asia use these frequency bands for mobile communication.
GSM-900 uses about 890-915 MHz to transmit data from the mobile station to the base station and 935-960 MHz for the opposite route, offering 124 RF channels. GSM-1800 uses about 1710-1785 MHz to transmit data from the mobile station to the base station and 1805-1880 MHz for the opposite route, offering 374 channels.
GSM-850 and GSM-1900 are primarily used in the United States, Canada and several other countries in the rest of the Americas.
GSM-850 uses about 824-849 MHz to transmit data from the mobile station to the base station and 869-894 MHz for the opposite route, offering 123 channels. GSM 1900 uses about 1850-1910 MHz to transmit data from the mobile station to the base station and 1930-1990 MHz for the opposite direction, offering 298 channels.
