Devices and methods for enabling matching paging occasions for a lightly connected wireless device

1. A method by a first network node for enabling paging of a user equipment, UE, in an inactive state, the method comprising:

while the UE is in a connected state or during an initial context setup for the UE, receiving, by the first network node, a UE identity index value for the UE;

storing the UE identity index value;

prior to transitioning the UE to the inactive state and while the UE is in a connected state, transmitting, by the first network node, the UE identity index value to a second network node;

transitioning the UE from the connected state to an inactive state;

using the UE identity index value to determine a paging occasion for transmitting a page to the UE; and

transmitting the page to the UE at the paging occasion.

2. The method of claim 1 , wherein the connected state comprises a lightly connected state.

3. The method of claim 1 , wherein the UE identity index value comprises:

an International Mobile Subscriber Identity, IMSI;

a portion of an IMSI; or

a checksum derived from the IMSI.

4. The method of claim 1 , wherein storing the UE identity index value comprises storing the UE identity index value with a UE context indicating a state of the UE as being connected.

5. The method of claim 1 , wherein the UE identity index value is received in a message from the UE.

6. The method of claim 1 , wherein the UE identity index value is received in a message from a core network node, the message comprising at least one of:

a handover request;

an initial context setup request;

a downlink NAS transport message; and

a Path Switch Request Acknowledge message.

7. The method of claim 1 , further comprising:

transmitting, by the first network node, the UE identity index value to a second network node for transmission of the page to the UE by the second network node.

8. The method of claim 7 , wherein the UE identity index value is transmitted to the second network node in a paging request.

9. The method of claim 1 , wherein the UE identity index value is transmitted to the second network node in a message, the message comprising:

a handover request; or

a response to a UE context request from the second network node.

10. The method of claim 1 wherein the first network node is a target network node and the UE identity index value for the UE is received from a source network node.

11. The method of claim 1 , wherein the UE identity index value is received by the first network node or transmitted to the second network node over an X2 interface.

12. The method of claim 1 , wherein transitioning the UE from the connected state to the inactive state comprises:

transmitting a suspend or release message to the UE, the suspend or release message ordering the UE to enter the inactive state or a sleep state.

13. A first network node for enabling paging of a user equipment, UE, in an inactive state, the network node comprising:

memory storing instructions; and

processing circuitry configured to execute the instructions to cause the first network node to:

while the UE is in a connected state or during an initial context setup for the UE, receive a UE identity index value for the UE;

store the UE identity index value;

prior to transitioning the UE to the inactive state and while the UE is in a connected state, transmit the UE identity index value to a second network node;

transition the UE from the connected state to an inactive state;

use the UE identity index value to determine a paging occasion for transmitting a page to the UE; and

transmit the page to the UE at the paging occasion.

14. The first network node of claim 13 , wherein the connected state comprises a lightly connected state.

15. The first network node of claim 13 , wherein the UE identity index value comprises:

an International Mobile Subscriber Identity, IMSI;

a portion of an IMSI; or

a checksum derived from the IMSI.

16. The first network node of claim 13 , wherein storing the UE identity index value comprises storing the UE identity index value with a UE context indicating a state of the UE as being connected.

17. The first network node of claim 13 , wherein the UE identity index value is received in a message from the UE.

18. The first network node of claim 13 , wherein the UE identity index value is received in a message from a core network node, the message comprising at least one of:

a handover request;

an initial context setup request;

a downlink NAS transport message; and

a Path Switch Request Acknowledge message.

19. The first network node of claim 13 , wherein the processing circuitry is further configured to execute the instructions to cause the first network node to:

transmit the UE identity index value to a second network node for transmission of the page to the UE by the second network node.

20. The first network node of claim 19 , wherein the UE identity index value is transmitted to the second network node in a paging request.

21. The first network node of claim 13 , wherein the UE identity index value is transmitted to the second network node in a message, the message comprising:

a handover request; or

a response to a UE context request from the second network node.

22. The first network node of claim 13 wherein the first network node is a target network node and the UE identity index value for the UE is received from a source network node.

23. The first network node of claim 13 , wherein the UE identity index value is received by the first network node or transmitted to the second network node over an X2 interface.

24. The first network node of claim 13 , wherein transitioning the UE from the connected state to the inactive state comprises:

transmitting a suspend or release message to the UE, the suspend or release message ordering the UE to enter the inactive state or a sleep state.