Achieving seamless service during unreachability of charging function entity

1. A method comprising:

obtaining an indication of a backup resource usage quota associated with a rating group of a user session for a user equipment configured to communicate via a mobile core network, wherein the rating group is subject to online charging and is one of a plurality of rating groups of the user session, and wherein the backup resource usage quota associated with the rating group is one of a plurality of backup resource usage quotas associated respectively with the plurality of rating groups;

determining that a charging function entity configured to provide an indication of a primary resource usage quota associated with the rating group is unreachable; and

in response to determining that the charging function entity is unreachable, allocating the backup resource usage quota associated with the rating group while the charging function entity is unreachable.

2. The method of claim 1 , wherein obtaining the indication of the backup resource usage quota associated with the rating group includes obtaining the indication of the backup resource usage quota associated with the rating group in a dedicated information element from the charging function entity.

3. The method of claim 1 , further comprising:

determining that a timer for the backup resource usage quota associated with the rating group has expired; and

in response to determining that the timer has expired, revoking an allocation of the backup resource usage quota.

4. The method of claim 3 , further comprising:

obtaining, from the charging function entity, an indication of an expiration of the timer in a dedicated information element.

5. The method of claim 1 , further comprising:

determining that the charging function entity is reachable; and

providing, to the charging function entity, an indication of an amount of actual resource usage under the backup resource usage quota associated with the rating group.

6. The method of claim 5 , further comprising:

obtaining an indication that the amount of the actual resource usage is equal to or greater than a threshold amount of resource usage, wherein

determining that the charging function entity is reachable includes:

providing a charging data request to the charging function entity in response to obtaining the indication that the amount of the actual resource usage is equal to or greater than the threshold amount of the resource usage; and

obtaining a charging data response from the charging function entity.

7. The method of claim 5 , wherein providing the indication of the amount of the actual resource usage includes providing the indication of the amount of the actual resource usage in a dedicated information element.

8. The method of claim 1 , wherein allocating the backup resource usage quota associated with the rating group includes providing, to a user plane function entity, an indication of the backup resource usage quota associated with the rating group.

9. An apparatus comprising:

a network interface configured to obtain or provide network communications; and

one or more processors coupled to the network interface, wherein the one or more processors are configured to:

obtain an indication of a backup resource usage quota associated with a rating group of a user session for a user equipment configured to communicate via a mobile core network, wherein the rating group is subject to online charging and is one of a plurality of rating groups of the user session, and wherein the backup resource usage quota associated with the rating group is one of a plurality of backup resource usage quotas associated respectively with the plurality of rating groups;

determine that a charging function entity configured to provide an indication of a primary resource usage quota associated with the rating group is unreachable; and

in response to determining that the charging function entity is unreachable, allocate the backup resource usage quota associated with the rating group while the charging function entity is unreachable.

10. The apparatus of claim 9 , wherein the one or more processors are configured to:

obtain the indication of the backup resource usage quota associated with the rating group in a dedicated information element from the charging function entity.

11. The apparatus of claim 9 , wherein the one or more processors are further configured to:

determine that a timer for the backup resource usage quota associated with the rating group has expired; and

in response to determining that the timer has expired, revoke an allocation of the backup resource usage quota.

12. The apparatus of claim 11 , wherein the one or more processors are further configured to:

obtain, from the charging function entity, an indication of an expiration of the timer in a dedicated information element.

13. The apparatus of claim 9 , wherein the one or more processors are further configured to:

determine that the charging function entity is reachable; and

provide, to the charging function entity, an indication of an amount of actual resource usage under the backup resource usage quota associated with the rating group.

14. The apparatus of claim 13 , wherein the one or more processors are further configured to:

obtain an indication that the amount of the actual resource usage is equal to or greater than a threshold amount of resource usage;

provide a charging data request to the charging function entity in response to obtaining the indication that the amount of the actual resource usage is equal to or greater than the threshold amount of the resource usage; and

obtain a charging data response from the charging function entity.

15. The apparatus of claim 13 , wherein the one or more processors are configured to:

provide the indication of the amount of the actual resource usage in a dedicated information element.

16. The apparatus of claim 9 , wherein the one or more processors are configured to:

provide, to a user plane function entity, an indication of the backup resource usage quota associated with the rating group.

17. One or more non-transitory computer readable storage media encoded with instructions that, when executed by a processor, cause the processor to:

obtain an indication of a backup resource usage quota associated with a rating group of a user session for a user equipment configured to communicate via a mobile core network, wherein the rating group is subject to online charging and is one of a plurality of rating groups of the user session, and wherein the backup resource usage quota associated with the rating group is one of a plurality of backup resource usage quotas associated respectively with the plurality of rating groups;

determine that a charging function entity configured to provide an indication of a primary resource usage quota associated with the rating group is unreachable; and

in response to determining that the charging function entity is unreachable, allocate the backup resource usage quota associated with the rating group while the charging function entity is unreachable.

18. The one or more non-transitory computer readable storage media of claim 17 , wherein the instructions further cause the processor to:

obtain the indication of the backup resource usage quota associated with the rating group in a dedicated information element from the charging function entity.

19. The one or more non-transitory computer readable storage media of claim 17 , wherein the instructions further cause the processor to:

determine that a timer for the backup resource usage quota associated with the rating group has expired; and

in response to determining that the timer has expired, revoke an allocation of the backup resource usage quota.

20. The one or more non-transitory computer readable storage media of claim 17 , wherein the instructions further cause the processor to:

determine that the charging function entity is reachable; and

provide, to the charging function entity, an indication of an amount of actual resource usage under the backup resource usage quota associated with the rating group.