2.5 GPRS Network Elements
As discussed in the previous paragraphs, GPRS works in a very different way compared to the circuit-switched GSM network. This is why three new network components were introduced into the mobile network and software updates had to be made for some of the existing components. Figure 2.16 gives an overview of the components of a GPRS network, which are described in more detail below.
2.5.1 The Packet Control Unit (PCU)
The BSC has been designed to switch 16 kbit/s circuit-switched channels between the MSC and the subscribers. It is also responsible for the handover decisions for those calls. As GPRS subscribers no longer have a dedicated connection to the network, the BSC and its switching matrix are not suited to handle packet-switched GPRS traffic. Therefore, this task has been assigned to a new network component, the PCU. The PCU is the packet-switched counterpart of the BSC and fulfills the following tasks: