Alternative methods for transferring data to mobile communications and GPRS
Standard data rates in GSM networks is only 9600 bps, but thanks to a technique known as HSGSP, associated with the provision of additional time slots for the implementation of a "conversation" can not raise it. Consider the options:
14.4 kbit / s
This speed can be obtained by reducing the signaling and truncated correcting errors, it is necessary to reduce the header (overhead), freed up resources to allow the transfer of data from the specified speed.
HSCSD (High Speed Circuit Switched Data)
The introduction of high-speed data transmission over dial-up connections through the provision of subscriber few time-slots will achieve significant gains in speed of data transmission. For example, a 2 time-slots, you can reach speeds of up to 28.8 kbit / s, while focussing on four, we get 57.6 kbps.
CDPO (Cellular Digital Packet Data)
How do GPRS is designed for GSM, CDPD is focused on both AMPS and CDMA. Allows you to reach speeds of up to 14.4 kbit / s, and in the case of the so-called "enhanced CDMA» will provide speeds up to 76.8 kbps.
GPRS (General Packet Radio Service)
This system is a packet switched data networks. It is expected that theoretically attainable speed can reach 171.2 kbit / s, although in the near future is hardly expect to achieve speeds over 111 kbps.
Motorola has proposed the following picture clearly represents the ratio of data transmission systems based on GSM
One major advantage of GPRS - is that is a way to transfer data at a higher speed than was possible until recently. Such high speeds make possible the introduction of a variety of applications - from undemanding to speed the transfer of SMS-cepvisa to high-speed data transmission in the local corporate network.
Time connect to GPRS will be almost instantaneous, so it is planned that will no longer pay for "time line" in the account will include volumes of information transmitted or received. This means that GPRS will be the most attractive technology for various applications, characterized by "explosive" nature of the data, such as e-mail, telemetry and other similar services. This also ensures compatibility with existing GPRS networks, packet-based TCP / IP or X.25.
Packet switching system is very efficient, because network resources are exploited only when the direct transfer of packages. Translated into common language - this means that the entire available range of the selected connection can be shared by all subscribers.
Basic properties of GPRS:
High data transfer speed - 171.2 kbit / s (average 111 kbit / s);
Rapid communication / Quick disconnection;
Facilitates the introduction of new services (eg, telemetry);
Supports other packet data network (TCP / IP, "X.25);
Subscribers share the physical resources of the network;
It provides mobile users with continued access to the networks of GSM / GPRS. Internet and corporate networks (Intranet);
Ability to use the resources of the GSM network in the off-peak periods.
Since GPRS is made based on GSM, the new equipment GPRS / GSM will provide access, as in the network GSM, and in the overlay network GPRS. However, so far, apparently, do not expect any other terminals, except terminals of class "C". Such terminals can operate simultaneously only in GSM mode or only in the mode of GPRS.
Because the GPRS network can share resources and is superimposed on the network of GSM, a significant point is its ability to load the network resources to "offpikovye" periods, for example, from 20:00 to 05:00.