LTE: In which scenarios SGW and PGW can be combined during deployment ?

Question

In LTE network, SGW and PGW nodes have been defined as two separate entities. Would those be separate nodes for deployment or combined ?

Answer 1

Functionality of SGW and PGW nodes are different that's why those are defined as separate nodes. For software point of view both are different but they can run side by side in the same machine. There are various use cases based on that decision would be taken whether SGW and PGW would be combined or not.

In case of roaming PGW and SGW would be in different network so in that case both the nodes would be running in different location physically. In other cases where handovers are not required or roaming is not supported, SGW and PGW can be implemented together. When I talk about implemented together it means a single process supporting both the interfaces S1-U and S5 interface.

Answer 2

It is depend on the cost for the network deployment. Typically for the 1 physical node can run both SGW and PGW function. If your network traffic is small, it would be better to use combined scenario.

If your network traffic is big, the budget is big as well, you cam make different physical node for SGW and PGW. The reciliency strategy will influence the decision whether using combined or separated S/PGW.