GSM (Global System for Mobile Communications) is a second-generation digital mobile telephone standard that uses a variation of Time Division Multiple Access (TDMA). It is the most widely used of the three digital wireless telephone technologies - CDMA (Code Division Multiple Access), GSM and TDMA.
GSM digitizes and compresses voice data, then sends it down a channel with two other streams of user data, each in its own time slot. It operates at 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 at March 2003, GSM digital wireless services were offered in some form in over 193 countries. In 2002, about 69% of all digital mobile subscriptions in the world used GSM phones on GSM networks.
only a small number of radio channel frequencies were available for GSM mobile systems, engineers had to find a way to reuse radio channels to carry more than one conversation at a time. The solution industry adopted was called frequency planning or frequency reuse. Frequency reuse was implemented by restructuring the mobile telephone system architecture into the cellular concept.
Cells are assigned a group of channels that is completely different from neighboring cells. The coverage area of cells is called the footprint. This footprint is limited by a boundary so that the same group of channels can be used in different cells that are far enough away from each other so that their frequencies do not interfere.
1 comment:
Hello. This post is likeable, and your blog is very interesting, congratulations :-). I will add in my blogroll =). If possible gives a last there on my blog, it is about the TV de Plasma, I hope you enjoy. The address is http://tv-de-plasma.blogspot.com. A hug.
Post a Comment