From GSM to LTE: An Introduction to Mobile Networks and Mobile Broadband

3.12 Radio and Core Network Enhancements: CPC and One Tunnel

While the evolution of wireless networks was mainly focused on increasing datarates for quite some time, other factors such as reducing power consumption and increasing efficiency of the core network architecture are also very important to keep the overall system viable. Starting with 3GPP Release 7, a number of enhancements were specified in that direction, CPC and one tunnel.

CPC is a package of features to improve the handling of mobile subscribers while they have a packet connection established, that is, while they have an IP address assigned. Taken together, they aim at reducing the number of state changes to minimize delay and signaling overhead. This was done by introducing enhancements to keep devices on the high-speed channels (in HSPA Cell-DCH state) for as long as possible, even while no data transfer is ongoing. To achieve this, it is necessary to reduce mobile power consumption while listening to the shared channels. If more mobile devices are kept in active state, it is also important to reduce the bandwidth requirements for radio layer signaling. And finally, the aim of the CPC features is to increase the overall number of mobile devices per cell that can be served simultaneously.

CPC does not introduce new revolutionary features. Instead, already existing features are modified to achieve the desired results. 3GPP TR 25.903 [23] gives an overview of the proposed changes and the following descriptions refer ...