The concept of data communication in GPRS is similar to the GSM network. The only difference is that it works on packet data transmission. GPRS has data rates of 9.6 to 171 kbps. The air interface is also the same for many users as in GSM. The architecture of GPRS is below.
The GSM network is used more efficiently in the present GPRS systems. The concept of this system is to build a packet based mobile network. The present network not only provides an interface for handling data but also has protocols.
GPRS Base Station Subsystem
- There is a need for software upgrade and installation of Packet control units for each BSC.
- For the BSS this PCU provides physical and logical data interference for packet data traffic.
- The BTS does not require hardware enhancement but needs software upgrade.
- When there is data traffic from the subscriber’s phone, it is sent to BTS through the air interface.
- Later on to BSC as normally in GSM call.
- At the output side both voice and data traffic are separated.
- Voice is sent to MSC as in GSM and data to SGSN via PCU.
General Packet Radio Service Support Nodes
The node has Gateway GPRS Support Nodes (GSNs) and, Serving GPRS Support Node (SGSN)
Gateway General Packet Radio Service. Support Node (GGSN)
It behaves as a router or an interface between the external networks. It not only has the routing information but also tunnels packers through IP based internal backbone. GGSN acts as a packet filter for incoming traffic. For use of external data networks it also collects charging information.
Serving General Packet Radio Service. Support Node (SGSN)
The main purpose of SGSN is
- To authenticate General Packet Radio Service mobiles.
- Registration of mobiles.
- Mobility management.
- To check information on charging so that it can be used in air interface.
This is an IP based network which carries packets between GSNs. The internal backbone does not require any information about the domain which is outside the GPRS network as it uses tunneling. SS7 signaling is also used from GSN to MSC and HLR.
The Routing area concept is explained well in General Packet Radio Service. This is quite similar to the location area of GSM. The small difference is the routing area has few cells compared to the location area. Hence it requires less radio resources for broadcasting a page message.