Why we have MME and SGW as saperate node in LTE?

Question

Where as in UMTS its a single SGSN node which serves the role of MME and SGW...Any thoughts....

Answer 1

In case of UMTS , SGSN was taking part both in user data and control signal.It means that it was the single gateway through which both user data and control signal was going.

Think a case like Suppose in sending user data some problem happened with the SGSN so at that time it will also not supports the controlling part signal.

So this is known as Single Point of Failure.

1> To deduce that they came up with two different entity like MME ans SGW. where ENB-SGW interface take care about USER DATA and ENB-MME can take care about the signalling part (authentication/mobility/paging )so that they can recover from single point of failure.

Answer 2

As per my knowledge, MME and SGW are logically separate notes. Both the nodes have different functionality all together. While moving ahead in the field of telecommunication, the major objective is to reduce complexity. I never worked for UMTS technology so don't have much idea. MME has different set of functions and SGW has different. MME has control over the mobility of user, whereas SGW deals with data plane. It's my personal thought that to reduce complexity in the network, 3GPP has defined two different nodes for different purposes. While considering mobility of a user, MME has concern about the tracking area, where as SGW has concern about serving area.