Packet-switched technique vs. circuit-switched

In circuit-switching, resources (e.g. a channel) are allocated to user for duration of connection
Inefficient use of resources
User pays for the whole connection
High QoS: channel maintains real-time connection
In packet-switching, resources are allocated to user only for the time it takes to send each packet
A channel can serve many users
User pays by the packet
Ideal for bursty data connections

Packet-switched

1.High bit rates
2.Shared bandwidth
3.Variable access times
4.Friendly bill (based on volume)
5.Robust application support
6.Frequent transmission of small volumes


Circuit-switched
1.Low bit rates
2.Reserved bandwidth
3.Fixed access time
4.Unfriendly bill (based on duration)
5.Limited application support
6.Large volumes


GPRS network architecture is built on top of the existing GSM network infrastructure.
To support packet switched functionality, GPRS introduces several new nodes in addition to the network nodes in the GSM.
There exist a Gateway GPRS Support Node (GGSN) and a Serving Support Node (SGSN). There is a backbone network that connects the SGSN and GGSN node together. Some of the existing GSM nodes should be upgraded with GPRS functionality.