GSM is a connection between two people − a caller and the called person – is the basic service of all telephone networks. To apply this service, the network must has ability to set up and maintain a call, which includes some tasks: identifying the called person, determining the location, routing the call, and ensuring that the connection is continued until conversation lasts. After the transaction, the connection is terminated.
In a fixed telephone network, providing and managing connections is an easy process, because telephones are connected by wires to the network and their location is permanent from the networks’ point of view. Whereas, in a mobile network, the establishment of a call is more complex task, because it doesn’t have wire and permanent location. It enables the users to move by wireless (radio) connection.
What is GSM?
GSM stands for Global System for Mobile Communication and is an open, digital cellular technology transmits mobile voice and data services. It is a digital mobile telephony system that is widely used technology in the world. The GSM market has more than 70 percent of the world’s digital cellular subscribers. The GSM makes use of narrowband Time Division Multiple Access (TDMA) technique for transmitting signals. The GSM was developed by using digital technology. It has an ability to carry 64 kbps to 120 Mbps of data rates.
GSM代表全球移动通信系统，是一种开放的数字蜂窝技术，可传输移动语音和数据服务。它是一种数字移动电话系统，是世界上广泛使用的技术。GSM市场拥有全球70％以上的数字蜂窝用户。GSM利用窄带时分多址（TDMA)技术发送信号。GSM是使用数字技术开发的。它能够承载64 kbps至120 Mbps的数据速率。
GSM operates at either the 900 MHz or 1800 MHz frequency band. In Europe, operates in the 900MHz and 1.8GHz bands and in US, operates 1.9GHz and 850MHz bands. The GSM is a circuit-switched system that divides each 200 kHz channel into eight 25 kHz time-slots.
GSM工作在900 MHz 或1800 MHz频段。在欧洲，运行在900MHz和1.8GHz频段，在美国，运行1.9GHz和850MHz频段。GSM是一个电路交换系统，它将每个200 kHz信道分成8个25 kHz时隙。
Cell phones use GSM network by searching for cell phone towers in the nearby area. GSM carriers have roaming contacts with other GSM carriers and typically cover rural areas more completely. GSM also has the advantage of using SIM (subscriber identity module) cards. The SIM card, which acts as your digital identity, is tied to your cell phone service carrier’s network rather than to the handset itself. This allows for easy exchange from one phone to another without new cell phone service activation.
Today, more than 690 mobile networks provide GSM services across 213 countries and GSM represents 82.4% of all global mobile connections. According to GSM World, there are now more than 2 billion GSM mobile phone users worldwide. GSM World references China as “the largest single GSM market, with more than 370 million users, followed by Russia with 145 million, India with 83 million and the USA with 78 million users.”
如今，超过690个移动网络在213个国家提供GSM服务，GSM占全球移动连接的82.4％。据GSM World称，目前全球有超过20亿的GSM手机用户。GSM World将中国称为“最大的单一GSM市场，拥有超过3.7亿用户，其次是俄罗斯，有1.45亿，印度有8300万，美国有7800万用户。”