Gsm Specification & Air Interface

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[pic] WHAT IS GSM???? GSM: GSM (Global System for Mobile Communications: originally from Groupe Spécial Mobile) is the most popular standard for mobile telephone systems in the world. The GSM Association, its promoting industry trade organization of mobile phone carriers and manufacturers, estimates that 80% of the global mobile market uses the standard. GSM Specifications-I RF Spectrum GSM 900 1. Mobile to BTS (uplink): 890-915 MHz 2. BTS to Mobile (downlink):935-960 MHz 3. Bandwidth: 2* 25 MHz GSM 1800 1. Mobile to BTS (uplink): 1710-1785 MHz 2. BTS to Mobile (downlink) 1805-1880 MHz 3. Bandwidth: 2* 75 MHz GSM…show more content…
The purpose of LPC is to reduce the bit rate. The LPC provides parameters for a filter that mimics the vocal tract. The signal passes through this filter, leaving behind a residual signal. Speech is encoded at 13 kbps. GSM Subscriber Services There are two basic types of services offered through GSM: telephony (also referred to as tele services) and data (also referred to as bearer services). Telephony services are mainly voice services that provide subscribers with the complete capability (including necessary terminal equipment) to communicate with other subscribers. Data services provide the capacity necessary to transmit appropriate data signals between two access points creating an interface to the network. In addition to normal telephony and emergency calling, the following subscriber services are supported by GSM: * Dual-tone multi-frequency (DTMF) —DTMF is a tone signaling scheme often used for various control purposes via the telephone network, such as remote control of an answering machine. GSM supports full-originating DTMF. * Facsimile group III —GSM supports CCITT Group 3 facsimile. As standard fax machines are designed to be connected to a telephone using analog signals, a special fax converter connected to the exchange is used in the GSM system. This enables a GSM–connected fax to communicate with any analog fax in the network. * Short message services —A convenient facility
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