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.
<标题>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代表全球移動通信系統，是一種開放的數字蜂窩技術，可傳輸移動語音和數據服務。它是一種數字移動電話系統，是世界上廣泛使用的技術。GSM市場擁有全球70％以上的數字蜂窩用戶。GSM利用窄帶時分多址（TDMA)技術發送信號。GSM是使用數字技術開發的。它能夠承載64 kbps至120 Mbps的數據速率。
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.
<标题>GSM工作在900 MHz 或1800 MHz頻段。在歐洲，運行在900MHz和1.8GHz頻段，在美國，運行1.9GHz和850MHz頻段。GSM是一個電路交換系統，它將每個200 kHz信道分成8個25 kHz時隙。
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.
<标题>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，超過690個移動網絡在213個國家提供GSM服務，GSM占全球移動連接的82.4％。據GSM World稱，目前全球有超過20億的GSM手機用戶。GSM World將中國稱為“最大的單一GSM市場，擁有超過3.7億用戶，其次是俄羅斯，有1.45億，印度有8300萬，美國有7800萬用戶。”