Per-flow jumbo MTU in NR systems

1. A method for wireless communications by a user equipment (UE), comprising:

determining a default maximum transmission unit (MTU) size to be used for communications in a packet data network (PDN);

determining based on an indication from a network function in the PDN, one or more per-flow MTU sizes, different than the default MTU size, to be used for communications in the PDN, wherein the indication comprises an indication of a smaller of the default MTU size, an MTU size supported by the network functions in the PDN, and an MTU size supported by a destination server; and

communicating in the PDN according to the determined per-flow MTU sizes.

2. The method of claim 1 , wherein the default MTU size is received during establishment of a PDN connection or a protocol data unit (PDU) session.

3. The method of claim 1 , wherein at least one of the one or more per-flow MTU sizes is greater than 1500 bytes.

4. The method of claim 1 , wherein the determination of the one or more per-flow MTU sizes is based on a size of a packet received from a device associated with the flow.

5. The method of claim 1 , wherein the determination comprises:

determining an uplink MTU size for a flow that is larger than the default MTU size if the received packet is larger than the default MTU size.

6. The method of claim 1 , wherein the network function is a session management function (SMF).

7. The method of claim 6 , wherein the indication is provided in a non-access stratum (NAS) signaling PDU session modification command.

8. The method of claim 1 , wherein the indication is from a base station (BS).

9. The method of claim 8 , wherein the indication is provided in an access stratum (AS) signaling message.

10. The method of claim 1 , wherein the determination of the one or more per-flow MTU sizes is based on a signal quality measurement.

11. The method of claim 1 , wherein the determination of the one or more per-flow MTU sizes is based on a radio access technology (RAT) associated with a dedicated radio bearer (DRB) used for the flow.

12. A method for wireless communications by a base station (BS), comprising:

configuring a user equipment (UE) with a default maximum transmission unit (MTU) size to be used for communications in a packet data network (PDN);

indicating one or more per-flow MTU sizes, different than the default MTU size, to be used by the UE for communications in the PDN;

receiving an indication of the one or more per-flow MTU sizes from a network function in the PDN via explicit network signaling, wherein the indication comprises an indication of a smaller of the default MTU size, an MTU size supported by the network functions in the PDN, and an MTU size supported by a destination server; and

communicating in the PDN according to the indicated per-flow MTU sizes.

13. The method of claim 12 , wherein the default MTU size is configured during establishment of a PDN connection or a protocol data unit (PDU) session with the UE.

14. The method of claim 12 , wherein at least one of the one or more per-flow MTU sizes is greater than 1500 bytes.

15. The method of claim 12 , wherein the network entity is an access and mobility management function (AMF).

16. The method of claim 12 , wherein the indication is provided via access stratum (AS) signaling.

17. A method for wireless communications by a network function, comprising:

determining a default maximum transmission unit (MTU) size to be used for communications in a packet data network (PDN);

detecting an MTU size supported by a destination server associated with the flow, wherein the indication comprises an indication of a smaller of the default MTU size, an MTU size supported by the network functions in the PDN, and the MTU size supported by the destination server; and

providing an indication to another network function of one or more per-flow MTU sizes, different than the default MTU size, to be used for communications in the PDN.

18. The method of claim 17 , wherein at least one of the one or more per-flow MTU sizes is greater than 1500 bytes.

19. The method of claim 17 , wherein the network function is a user plane function (UPF).

20. The method of claim 17 , wherein the other network function is a session management function (SMF).

21. The method of claim 17 , wherein the destination server comprises an edge caching server.

22. The method of claim 17 , wherein detecting the MTU size supported by the destination server comprises:

pinging the destination server to discover the MTU size supported by the destination server.

23. The method of claim 17 , wherein pinging the destination server comprises:

sending the destination server a packet larger than the default MTU size; and

determining if the destination server successfully receives the packet.

24. The method of claim 17 , wherein detecting the MTU size supported by the destination server comprises:

receiving a packet from the destination server; and

determining the MTU size supported by the destination server based on a size of the received packet.

25. The method of claim 17 , further comprising:

receiving a packet from the destination server; and

indicating to the destination server that the packet size is not supported if the size of the packet is larger than the per-flow MTU size associated with the flow.