GSM frequency

GSM networks operate in a number of different carrier frequencies (separated into GSM frequency ranges for 2 G and UMTS frequency bands 3 g), with most 2 G GSM networks operating in the range of 900 Mhz and 1800 Mhz. When all of these bands were assigned, instead, used all the 850 Mhz and 1900 Mhz bands (e.g. in Canada and the United States of America). In rare cases, 400 and 450 Mhz frequency bands allocated in some countries because they previously used for first-generation systems.

Most 3 G networks in Europe operate in the 2100 Mhz band.

Regardless of the frequency selected on the operator consists of the timeslots for individual phones to use. This eight full-rate or sixteen half-rate speech channels per radio frequency. These eight radio timeslots (or eight burst periods) grouped in a frame TDMA. Half the channels use the same slot alternative dates. Speed channel for all 8 channels is 270.833 kbit/s, and the duration of the image is 4.615 Ms.

Transmit power in the handset is limited to a maximum of 2 W in GSM 850/900 and 1 Watt in GSM1800/1900.http://gsminfobd.blogspot.com/