System and Method for Distributed Evolved Packet Core Architecture

1. A method of managing a user session and an internet protocol (IP) session for a connection between an user equipment (UE) and a network, comprising: establishing, at a first distributed evolved packet core (EPC), the user session and the IP session over the connection through the first distributed EPC, wherein the first distributed EPC comprises a first packet data network (PDN) gateway (PGW) at which the IP session is anchored; holding original IP resources for the IP session and releasing original connection resources for the user session at the first distributed EPC when the UE moves beyond the first distributed EPC to a second distributed EPC; establishing a tunnel between the first PGW and a second PGW for the second distributed EPC, wherein the tunnel utilizes the original IP resources and new connection resources at the second distributed EPC; and routing data for the user session and the IP session from the tunnel, through the first PGW, and to the network.

2. The method of claim 1 wherein the holding the original IP resources and the releasing the original connection resources further comprise informing a home subscriber server (HSS) at a centralized EPC.

3. The method of claim 2 wherein the establishing the tunnel includes re-authenticating the UE with the HSS according to the original IP resources.

4. The method of claim 3 wherein the establishing the tunnel includes obtaining values of the original IP resources from the HSS.

5. The method of claim 2 wherein the establishing the tunnel includes coordinating, by a first mobility management entity (MME) at the first distributed EPC, with a second MME at the second distributed EPC according to the original IP resources.

6. The method of claim 5 wherein the coordinating between the first MME and the second MME is carried out through information stored in the HSS.

7. The method of claim 1 further comprising receiving a request, at a second mobility management entity (MME) at the second distributed EPC, from the UE to release the original connection resources and to maintain the original IP resources and the IP session.

8. The method of claim 7 further comprising forwarding the request to release the original connection resources to a first MME at the first distributed EPC.

9. The method of claim 1 further comprising establishing another IP session for another connection via the second PGW to the network after the UE moves to the second distributed EPC.

10. The method of claim 1 wherein the establishing the user session and the IP session, the holding and releasing, the establishing the tunnel, and the routing are carried out by virtual functions implemented on at least one processing system.

11. A distributed evolved packet core (EPC), comprising: a user plane couplable between a network and a radio node serving a user equipment (UE), wherein the user plane comprises: a packet data network gateway (PGW) configured to anchor an internet protocol (IP) session for the UE, and a serving gateway (SGW) configured to anchor a user session for the UE; and a control plane comprising a mobility management entity (MME) configured to coordinate a first connection for the IP session and the user session and, when the UE transitions to being served by another radio node coupled to another distributed EPC, to: instruct the PGW to release connection resources and hold IP resources for the first connection, inform a centralized EPC of the release and the hold, and coordinate a second connection for the IP session and the user session through a tunnel between the PGW and another PGW for the another distributed EPC according to an authorization from the centralized EPC.

12. The distributed EPC of claim 11 wherein the radio node comprises an enhanced node B (eNB).

13. The distributed EPC of claim 11 wherein the SGW is further configured to anchor the user session for UE mobility among a plurality of radio nodes couplable to the SGW.

14. The distributed EPC of claim 11 wherein the control plane is couplable to a home subscriber server (HSS) at the centralized EPC.

15. The distributed EPC of claim 14 wherein the MME is further configured to authenticate the UE with the HSS for the first connection.

16. The distributed EPC of claim 11 wherein the MME is further configured to receive a request from another MME for the another distributed EPC to release the connection resources and to maintain the IP session for the first connection, wherein the request originates at the UE and passes from the UE to the another radio node, to the another MME.

17. The distributed EPC of claim 11 wherein the control plane further comprises a policy and charging rules function (PCRF) coupled to the PGW and configured to administer subscriber policies for the UE through PGW.

18. The distributed EPC of claim 11 wherein the PGW, the SGW, and the MME are implemented as virtual functions on at least one processing system.

19. An evolved packet core (EPC) for serving a user equipment (UE), comprising: a central EPC having a home subscriber server (HSS) configured to store authentication information and to authenticate and identify the UE; a first distributed EPC having: a first serving gateway (SGW) couplable to a first radio node and configured to anchor a user session for the UE and to route user data to and from the UE through the first radio node, a first packet data network gateway (PGW) couplable between the first SGW and a network and configured to anchor an internet protocol (IP) session for the UE and to route the user data between the first SGW and the network, and a first mobility management entity (MME) configured to receive an authentication of the UE from the HSS and coordinate establishment of the user session and the IP session; and a second distributed EPC having: a second SGW couplable to a second radio node and configured to route the user data to and from the second radio node, a second PGW couplable between the second SGW and the network and configured to route the user data between the second SGW and the network, and a second MME; wherein, when the UE transitions from being served by the first radio node to being served by the second radio node, the first MME is configured to: instruct the first PGW to release connection resources for the user session and to hold IP resources for the IP session, and inform the HSS of the release of the connection resources and of the hold of the IP resources; and wherein, when the UE initiates connectivity with the second radio node, the second MME is configured to: receive a re-authentication of the UE from the HSS, and coordinate with the HSS and the first MME to establish a tunnel between the first PGW and the second PGW according to the IP resources and through which the user data can be routed from the UE to the second PGW, to the first PGW, and to the network.

20. The EPC of claim 19 wherein the second MME is further configured to establish new IP sessions for the UE with the second PGW routed directly to the network.

21. The EPC of claim 19 wherein the central EPC further comprises a subscriber provisioning repository configured to store subscriber information for the UE.

22. The EPC of claim 19 wherein the first distributed EPC further comprises a policy and charging rules function coupled to the first MME and the first PGW and configured to provide dynamic quality of service (QoS) policies for the first PGW.

23. The EPC of claim 19 wherein the second MME is further configured to receive an address for the first PGW when the UE initiates connectivity with the second radio node.

24. The EPC of claim 19 wherein the second MME is further configured to: receive a request from the UE to release the connection resources; and forward the request to the first MME.

25. The EPC of claim 19 wherein the first distributed EPC further comprises a server on which the first MME is implemented as a virtual function.

26. The EPC of claim 19 wherein the HSS is further configured to store the IP resources for the UE in a location database.

27. The EPC of claim 19 wherein the first SGW, the first PGW, and the first MME are implemented as virtual functions on at least one processing system.