Roaming support for next generation slice architecture

1. A method for operating a core network including a common core network function (CCNF) and a network slice selector (NSS), the method comprising:

receiving an attach request from a user equipment (UE) at the CCNF in a visited network providing a roaming service for a home network;

transmitting a slice request from the CCNF in the visited network to the NSS in the visited network;

transmitting, from the NSS in the visited network, the slice request to a home NSS in the home network;

receiving, by the NSS in the visited network from the home NSS in the home network, a response to the slice request that includes an identity of a home network slice selected by the home NSS in the home network based on the slice request;

selecting, by the NSS in the visited network, based on criteria included in the slice request from the CCNF, at least one network slice in the visited network that corresponds to the home network slice; and

transmitting, by the CCNF in the visited network, an attach response to the UE based on the selected at least one network slice in the visited network and the home network slice.

2. The method of claim 1 , wherein the CCNF receives the attach request from the UE through an access network.

3. The method of claim 1 , wherein the CCNF authenticates or authorizes the attach request before transmitting the slice request.

4. The method of claim 1 , wherein selecting, by the NSS in the visited network, the at least one network slice in the visited network comprises:

selecting a first slice in the visited network based on multi-descriptor information;

transmitting the slice request to the home NSS in the home network after selecting the first slice; and

receiving, from the home NSS in the home network in response to the slice request, the identity of the home network slice that corresponds to the first slice.

5. The method of claim 1 , wherein selecting, by the NSS in the visited network, the at least one network slice in the visited network comprises:

selecting, after receiving the identity of the home network slice, a second slice in the visited network corresponding to the home network slice based on multi-descriptor information.

6. The method of claim 1 , wherein the attach response includes a temporary identification.

7. The method of claim 1 , further comprising:

receiving a protocol data unit (PDU) session establishment request at the CCNF;

transmitting a request to the NSS for routing information;

receiving a response to the request from the NSS; and

establishing a PDU session based on the at least one network slice or another network slice.

8. The method of claim 7 , wherein the response includes an identity of at least one control plane function.

9. The method of claim 1 , wherein selecting the at least one network slice in the visited network by the NSS in the visited network comprises:

selecting a first slice in the visited network based on multi-descriptor information;

transmitting a request to a control entity in a home network; and

receiving an identity of the home network slice corresponding to the first slice from the control entity in the home network.

10. A server comprising:

a common core network function (CCNF) in a visited network providing a roaming service for a home network; and

a network slice selector (NSS) coupled to the CCNF in the visited network,

wherein the CCNF in the visited network is configured to:

receive an attach request from a user equipment (UE), and

transmit a slice request to the NSS in the visited network,

wherein the NSS in the visited network is configured to:

transmit the slice request to a home NSS in the home network,

receive, from the home NSS in the home network, a response to the slice request that includes an identity of a home network slice selected by the home NSS in the home network based on the slice request, and

select, based on criteria included in the slice request, at least one network slice in the visited network that corresponds to the home network slice, and

wherein the CCNF in the visited network is configured to transmit an attach response based on the selected at least one network slice in the visited network and the home network slice.

11. The server of claim 10 , wherein the CCNF is configured to receive the attach request from the UE through an access network.

12. The server of claim 10 , wherein the CCNF is configured to authenticate or authorize the attach request before transmitting the slice request.

13. The server of claim 10 , wherein selecting the at least one network slice in the visited network comprises:

selecting a first slice in the visited network based on multi-descriptor information;

transmitting the slice request to the home NSS in the home network after selecting the first slice; and

receiving, from the NSS in the home network in response to the slice request, the identity of the home network slice that corresponds to the first slice.

14. The server of claim 10 , wherein the NSS in the visited network is further configured to:

select, after receiving the identity of the home network slice, a second slice in the visited network corresponding to the home network slice based on multi-descriptor information.

15. The server of claim 10 , wherein the attach response includes a temporary identification.

16. The server of claim 10 , wherein the CCNF is further configured to:

receive a protocol data unit (PDU) session establishment request at the CCNF;

transmit a request to the NSS for routing information;

receive a response to the request from the NSS; and

establish a PDU session based on the at least one network slice or another network slice.