GPRS
What is GPRS?
The General Packet Radio Service (GPRS) network is an “always on”, private network for data. It uses the existing GSM network to transmit and receive TCP/IP based data to and from GPRS mobile devices. Private IP addresses are typically dynamically assigned within the network to mobile devices. However, Access Point Names (APN’s) provide a gateway route to other networks such as the Internet, WAP services or private corporate networks. Firewalls typically reside at the APN to isolate the public and private networks. IP addresses allocated to mobile GPRS devices are therefore not addressable from outside the GPRS network (e.g. from the Internet) without specialised services or infrastructure.
Private network access to GPRS devices
Although client GPRS devices can communicate with ease over Public and Private networks, GPRS server devices require a static IP address. Network Operators offer private APN’s to corporate networks over Leased Lines or VPN’s, where IP address assignment is managed by the customer’s corporate Network e.g. using a radius server. Alternatively, Wireless Operators in some countries offer private APN’s with static IP address support thereby creating customers their own private network within the GPRS network.
GPRS mobile device
There are a number of GPRS devices, each of which can offer GSM services too, such as voice calls and SMS.
A GPRS Mobile Phone
A GPRS Radio Card for a PC
A Hand held PC with an in-built GPRS Mobile
A remote machine
GPRS classes
There are 3 classes of GPRS device being developed, of which only class B is currently available: –
Class A – Operates in GSM and GPRS modes at the same time, and hold simultaneous voice and data sessions.
Class B – Operates in GSM and GPRS modes at the same time, and but cannot hold simultaneous calls.
Class C – Can be active in either GSM or GPRS mode, but not at the same time
Benefits
Efficient – GPRS mobile devices only use the GSM network when data is transferred. The GSM connection is not dedicated to each user, therefore it can be shared with many users resulting in efficient use of the network.
Fast – GPRS gives speeds of upto 5 time faster than GSM. GPRS offers maximum data rates of 56Kbps (down) and 14.4kbps (up), however this is shared bandwidth therefore actual data rates are potentially lower.
Payment based on data usage – Billing is not based on time, but on the amount of data actually transferred.