Communication method and communications apparatus for determining latency of transmission between network elements

1. A method, comprising:

receiving, by a user equipment (UE), first latency information of a flow from a session management function (SMF) network element or a user plane function (UPF) network element, wherein the first latency information indicates a first latency of transmitting the flow from a flow service provider in a time sensitive network (TSN) to the UE;

determining, by the UE, a second latency based on the first latency and a first target latency, wherein the first target latency is a latency of transmitting the flow from the UE to a target network element that is in the TSN network and that is used as a next hop of the UE, and the second latency is a latency of transmitting the flow from the flow service provider to the target network element; and

sending, by the UE, second latency information to the target network element, wherein the second latency information indicates the second latency.

2. The method according to claim 1 , wherein the first latency information is received by the UE from the SMF network element.

3. The method according to claim 1 , wherein the first latency information is received by the UE from the UPF network element.

4. The method according to claim 1 , wherein determining, by the UE, the second latency based on the first latency and the first target latency comprises:

determining, by the UE, the second latency by adding the first latency and the first target latency.

5. The method according to claim 1 , further comprising:

obtaining, by the UE, the first target latency from the target network element.

6. The method according to claim 1 , wherein the first latency information is received by the UE in a flow service provider broadcast declaration message.

7. A method, comprising:

receiving, by a user equipment (UE), first latency information of a flow, wherein the first latency information indicates a first latency of transmitting the flow from a flow service provider in a time sensitive network (TSN) to a first communications device;

sending, by the UE, information about the flow to a session management function (SMF) network element, wherein the information about the flow is used to determine a quality of service parameter corresponding to the flow;

receiving, by the UE, the quality of service parameter corresponding to the flow from the SMF network element;

determining, by the UE, a first target latency based on the quality of service parameter corresponding to the flow, wherein the first target latency is a latency of transmitting the flow between the UE and a user plane function (UPF) network element;

determining, by the UE, a third latency based on the first latency, the first target latency, and a second target latency, wherein the second target latency is a latency of transmitting the flow from a second communications device to a target network element that is in the TSN network and that is used as a next hop of the second communications device, and the third latency is a latency of transmitting the flow from the flow service provider to the target network element; and

sending, by the UE, third latency information, wherein the third latency information indicates the third latency.

8. The method according to claim 7 , wherein the first communications device is the UPF network element, and the second communications device is the UE.

9. The method according to claim 7 , wherein the first communications device is the UE, and the second communications device is the UPF network element.

10. The method according to claim 7 , wherein the information about the flow comprises a destination address, a source address, a maximum frame size, a maximum frame interval, a priority of the frame, a maximum allowable latency of transmitting a single frame of the flow, a reliability requirement of the flow, a resource reservation failure cause, or an identifier of the flow.

11. The method according to claim 7 , wherein receiving, by the UE, the first latency information of a flow comprises:

receiving, by the UE, the first latency information of the flow and the information of the flow from the UPF network element in a flow service provider broadcast declaration message.

12. The method according to claim 11 , wherein sending, by the UE, the information about the flow to the SMF network element comprises:

forwarding, by the UE, the flow service provider broadcast declaration message to the SMF network element.

13. The method according to claim 7 , wherein the information about the flow comprises a destination address or a source address.

14. The method according to claim 7 , wherein the information about the flow comprises a maximum frame size or a maximum frame interval.

15. A user equipment (UE), comprising:

a processor;

a non-transitory computer-readable storage medium storing a program that is executable by the processor;

a receiver, configured to receive first latency information of a flow, wherein the first latency information indicates a first latency of transmitting the flow from a flow service provider in a time sensitive network (TSN) to a first communications device; and

a transmitter, configured to send information about the flow to a session management function (SMF) network element, wherein the information about the flow is used to determine a quality of service parameter corresponding to the flow;

wherein the receiver is further configured to receive the quality of service parameter corresponding to the flow from the SMF network element;

wherein the program includes instructions for:

determining a first target latency based on the quality of service parameter corresponding to the flow, wherein the first target latency is a latency of transmitting the flow between the UE and a user plane function (UPF) network element;

determining a third latency based on the first latency, the first target latency, and a second target latency, wherein the second target latency is a latency of transmitting the flow from a second communications device to a target network element that is in the TSN network and that is used as a next hop of the second communications device, and the third latency is a latency of transmitting the flow from the flow service provider to the target network element; and

wherein the transmitter is further configured to send third latency information, wherein the third latency information indicates the third latency.

16. The UE according to claim 15 , wherein the first communications device is the UPF network element, and the second communications device is the UE.

17. The UE according to claim 15 , wherein the first communications device is the UE, and the second communications device is the UPF network element.

18. The UE according to claim 15 , wherein the information about the flow comprises a destination address, a source address, a maximum frame size, a maximum frame interval, a priority of the frame, a maximum allowable latency of transmitting a single frame of the flow, a reliability requirement of the flow, a resource reservation failure cause, or an identifier of the flow.

19. The UE according to claim 15 , wherein the receiver being configured to receive the first latency information of the flow comprises the receiver being configured to:

receive the first latency information of the flow and the information of the flow from the UPF network element in a flow service provider broadcast declaration message.

20. The UE according to claim 19 , wherein the transmitter being configured to send the information about the flow to the SMF network element comprises the transmitter being configured to:

send the received flow service provider broadcast declaration message to the SMF network element.