Технологии


GPRS

GPRS (General Packet Radio Service) stands for General Packet Radio Service. Superstructure over mobile technology GSM, performs packet data transmission. GPRS allows the user of the mobile phone to exchange data with other devices in the GSM network and external networks, including the Internet. GPRS involves charging by volume data sent / received, and not time. 
GPRS - Network is a packet data. This kind of superstructure over conventional GSM cellular network that can transmit data at much higher than usual GSM network speeds. If the conventional GSM-network to get the most 14.4 kbit / s, the theoretical maximum GPRS is 171.2 kbit / s with full ispolzovanii.GPRS - this packet data transmission system operates similarly to cetyu Internet. Entire data stream sender is divided into separate packages and then delivered to the recipient, where packets come together, and it is not necessary that all packages will go one route. 
At a structural level, the GPRS system can be divided into two parts: a base station subsystem (BSS) and a core network GPRS (GPRS Core Network). 
In all BSS includes base stations and controllers that support packet data transfer. To do this, BSC (Base Station Controller) is complemented by the PCU - PCU (Packet Controller Unit), and BTS (Base Transceiver Station) - encoder GSM formats, protocols used by TCP / IP. 
Gateways to external networks (Internet, intranet, X.25) called GGSN (Gateway GPRS Support Node). The information exchange between SGSN and GGSN takes IP-based protocols. 
Also in the GPRS Core includes DNS (Domain Name System) and Charging Gateway (Gateway to communicate with the billing system). 
GPRS technology uses GMSK-modulation. Depending on the quality of the radio signal, the data sent by radio air, encoded by one of the 4-hkodovyh schemes (CS1-CS4). Each code scheme is characterized by redundant coding and noise immunity, and is automatically selected depending on the quality of the radio signal. In the same way and using the same equipment, the technology works and EDGE. But inside timeslot (channel separation unit) EDGE uses a different, more dense packing of information (modulation 8PSK).