GSM (Global System for Mobile Communications),

Tag : Fixed Wireless GSM

GSM (Global System for Mobile Communications) is asecond-generation digital mobile telephone standard using avariation of Time Division Multiple Access (TDMA). It is the mostwidely used of the three digital wireless telephone technologies -CDMA (Code Division Multiple Access), GSM and TDMA. GSM digitizesand compresses voice data, then sends it down a channel with twoother streams of user data, each in its own time slot. It operatesat either the 900, 1800 or 1,900MHz frequency bands.
GSM was initially developed as a pan-European collaboration,intended to enable mobile roaming between member countries. As atMarch 2003, GSM digital wireless services were offered in some formin over 193 countries. In June 2002, about 69% of all digitalmobile subscriptions in the world used GSM phones on GSM networks. TECHNICAL DETAILS
The GSM network can be divided into three broad parts The subscriber carries the mobile station The base station subsystem controls the radio link with the mobilestation The network subsystem performs the switching of calls between themobile users and other mobile and fixed network users MOBILE STATION
The mobile station consists of the mobile equipment, i.e. thehandset, and a smart card called the Subscriber Identity Module(SIM). The SIM provides personal mobility, so that the user canhave access to subscribed services irrespective of a specificterminal. By inserting the SIM card into another GSM terminal, theuser is able to receive and make calls from that terminal, andreceive other subscribed services.
The mobile equipment is uniquely identified by the InternationalMobile Equipment Identity (IMEI). The SIM card contains theInternational Mobile Subscriber Identity (IMSI) used to identifythe subscriber to the system, a secret key for authentication andother information. The IMEI and the IMSI are independent, therebyallowing personal mobility. The SIM card may be protected againstunauthorised use by a password or personal identity number. BASE STATION