Uplink signal transmission based on timing advance adjustment

1. An uplink signal transmission method, the method comprising:

sending, by a terminal device, an uplink signal to a network device in response to determining that a first variation meets a timing advance (TA) update condition, wherein the first variation indicates a strength change value of a downlink signal received by the terminal device;

receiving, by the terminal device, first information from the network device;

in response to determining that the first information comprises TA information, adjusting, by the terminal device, an uplink transmission time based on the TA information; and

in response to determining that the first variation does not meet the TA update condition and that a timer configured by the terminal device expires, sending, by the terminal device to the network device, a random access request that carries a first preamble, wherein the first preamble is a preamble configured by the network device for the terminal device.

2. The method according to claim 1 , wherein the sending, by the terminal device, the uplink signal to the network device comprises:

in response to determining that the first variation is greater than a third threshold, sending, by the terminal device, the random access request to the network device.

3. The method according to claim 2 , wherein the first information comprises indication information, the method further comprises:

determining, by the terminal device based on the indication information, that the terminal device does not send an uplink data signal on a resource preconfigured by the network device.

4. The method according to claim 1 , wherein the strength change value of the downlink signal comprises a change value of reference signal received power (RSRP) of the terminal device.

5. An uplink signal transmission method, the method comprising:

receiving, by a network device, an uplink signal from a terminal device in response to determining that a first variation meets a timing advance (TA) update condition, wherein the first variation indicates a strength change value of a downlink signal received by the terminal device;

generating, by the network device, first information based on the uplink signal, wherein in response to determining that TA information can be generated, the first information comprises the TA information, and the TA information indicates the terminal device to adjust an uplink transmission time;

sending, by the network device, the first information to the terminal device; and

receiving, by the network device, a random access request that carries a first preamble from the terminal device, wherein the first preamble is a preamble configured by the network device for the terminal device, and wherein the random access request is sent by the terminal device in response to determining that the first variation does not meet the TA update condition and that a timer configured by the terminal device expires.

6. The method according to claim 5 , wherein the receiving, by the network device, the uplink signal from the terminal device comprises:

receiving, by the network device, the random access request from the terminal device.

7. The method according to claim 5 , wherein in response to determining that the TA information cannot be generated, the first information comprises indication information, and the indication information indicates the terminal device not to send an uplink data signal on a resource preconfigured by the network device, indicates the terminal device to send the random access request, or indicates the terminal device to send an uplink data signal in an early data transmission manner.

8. The method according to claim 5 , wherein the strength change value of the downlink signal comprises a change value of reference signal received power (RSRP) of the terminal device.

9. A terminal device, the device comprising:

at least one processor; and

one or more memories coupled to the at least one processor and storing programming instructions for execution by the at least one processor to:

send an uplink signal to a network device in response to determining that a first variation meets a timing advance (TA) update condition, wherein the first variation indicates a strength change value of a downlink signal received by the terminal device;

receive first information from the network device;

in response to determining that the first information comprises TA information, adjust an uplink transmission time based on the TA information; and

in response to determining that the first variation does not meet the TA update condition and that a timer configured by the terminal device expires, send, to the network device, a random access request that carries a first preamble, wherein the first preamble is a preamble configured by the network device for the terminal device.

10. The terminal device according to claim 9 , wherein

that the first variation meets the timing advance (TA) update condition comprises that the first variation is greater than a third threshold; and

the uplink signal is a demodulation reference signal (DMRS) or the random access request.

11. The terminal device according to claim 10 , wherein the programming instructions further cause the at least one processor to: in response to determining that the first information comprises indication information, determine, based on the indication information, that the terminal device does not send an uplink data signal on a resource preconfigured by the network device.

12. The terminal device according to claim 9 , wherein the strength change value of the downlink signal comprises a change value of reference signal received power (RSRP) of the terminal device.

13. A network device, the device comprising:

at least one processor; and

one or more memories coupled to the at least one processor and storing programming instructions for execution by the at least one processor to:

receive an uplink signal from a terminal device in response to determining that a first variation meets a timing advance (TA) update condition, wherein the first variation indicates a strength change value of a downlink signal received by the terminal device;

generate first information based on the uplink signal, wherein in response to determining that TA information can be generated, the first information comprises the TA information, and the TA information indicates the terminal device to adjust an uplink transmission time;

send the first information to the terminal device; and

receive a random access request that carries a first preamble from the terminal device, wherein the first preamble is a preamble configured by the network device for the terminal device, and wherein the random access request is sent by the terminal device in response to determining that the first variation does not meet the TA update condition and that a timer configured by the terminal device expires.

14. The network device according to claim 13 , wherein the programming instructions further cause the at least one processor to: receive the random access request from the terminal device.

15. The network device according to claim 13 , wherein the programming instructions further cause the at least one processor to: in response to determining that the TA information cannot be generated, the first information comprises indication information, and the indication information indicates the terminal device not to send an uplink data signal on a resource preconfigured by the network device, indicates the terminal device to send the random access request, or indicates the terminal device to send an uplink data signal in an early data transmission manner.

16. The network device according to claim 13 , wherein the strength change value of the downlink signal comprises a change value of reference signal received power (RSRP) of the terminal device.