UE feedback of timing adjustment after a measurement gap

1. A method performed by a UE in a wireless network, comprising:

receiving, from a base station, timing advance parameter values which indicate a time difference measured by the base station between uplink and downlink for a band occupied by one or more serving cells;

calculating a timing advance feedback for the one or more serving cells based on the timing advance parameter values, a UE-controlled accumulated timing accuracy, and a beginning time for the timing advance feedback, wherein the UE-controlled accumulated timing accuracy indicates a difference between a network-requested timing advance and an actual timing advance that can be achieved by the UE; and

sending the timing advance feedback to the base station.

2. The method of claim 1 , wherein the timing advance feedback is a post-measurement gap (post-MG) time period after a measurement gap before uplink transmission, and the beginning time for the timing advance feedback is an ending time of the measurement gap.

3. The method of claim 2 , wherein, when no timing advance is applied to the measurement gap, the further comprises:

skipping uplink transmission of N slots, starting from a first one of the N slots that occurs immediately after the measurement gap and is fully non-overlapped with the measurement gap, wherein each of the N slots is defined with respect to a subcarrier spacing of an uplink carrier in the frequency layer.

4. The method of claim 2 , wherein, when a timing advance is applied to the measurement gap, the further comprises:

skipping uplink transmission of N slots, starting from a first one of the N slots occurring immediately after a given slot that is partially overlapped with the measurement gap, wherein each of the N slots and the given slot is defined with respect to a subcarrier spacing of an uplink carrier in the frequency layer.

5. The method of claim 2 , wherein, when no timing advance is applied to the measurement gap, the further comprises:

skipping uplink transmission of M symbols, starting from a first one of the M symbols that occurs immediately after the measurement gap and is fully non-overlapped with the measurement gap, wherein each of the M symbols is defined with respect to a subcarrier spacing of an uplink carrier in the frequency layer.

6. The method of claim 2 , wherein, when a timing advance is applied to the measurement gap, the further comprises:

skipping uplink transmission of M symbols, starting from a first one of the M symbols occurring immediately after a given symbol that is partially overlapped with the measurement gap, wherein each of the M symbols and the given symbol is defined with respect to a subcarrier spacing of an uplink carrier in the frequency layer.

7. The method of claim 1 , wherein sending the timing advance feedback further comprises:

calculating a number of slots impacted by the timing advance feedback based on a subcarrier spacing of an uplink carrier in a frequency layer; and

sending the number of slots as the timing advance feedback to the base station.

8. The method of claim 1 , wherein sending timing advance feedback further comprises:

calculating a number of symbols impacted by the timing advance feedback based on a subcarrier spacing of an uplink carrier in a frequency layer; and

sending the number of symbols as the timing advance feedback to the base station.

9. The method of claim 1 , wherein sending the timing advance feedback further comprises:

sending a time value indicating the length of the timing advance feedback to the base station.

10. The method of claim 1 , wherein sending the timing advance feedback further comprises:

sending the timing advance feedback in response to a command from the base station.

11. The method of claim 1 , wherein sending the timing advance feedback further comprises:

sending the timing advance feedback periodically according to a time period configuration.

12. The method of claim 1 , wherein the timing advance parameter values include an N TA value and an N TA_offset value used by the UE to compensate for the timing difference between the uplink and the downlink for a timing advance group (TAG) including the one or more serving cells.

13. The method of claim 12 , further comprising:

updating the N TA value from N TA_old to N TA_new by calculating:

N

T

⁢

A

-

⁢

n

⁢

e

⁢

w

=

N

T

⁢

A

-

⁢

o

⁢

l

⁢

d

+

(

T

A

-

31

)

×

1

⁢

6

×

6

⁢

4

2

⁢

μ

for a subcarrier spacing of 2 μ ·15 kHz, wherein T A is an index value provided by the base station; and

calculating a length of the timing advance feedback by evaluating: (N TA_new +N TA_offset )×Tc+ΔT AT , wherein Tc is a time unit value known to the UE and ΔT AT is the UE-controlled accumulated timing accuracy.

14. The method of claim 1 , further comprising:

calculating a respective timing advance feedback for each of a plurality of timing advance groups (TAGs) associated with the UE based on respective timing advance parameter values; and

sending the respective timing advance feedback for each TAG to the wireless network.

15. The method of claim 1 , wherein the wireless network is a Fifth Generation New Radio (5G NR) network.

16. An apparatus for wireless communication, the apparatus being a user equipment terminal (UE), comprising:

a memory; and

processing circuitry coupled to the memory and operative to:

receive, from a base station, timing advance parameter values which indicate a time difference measured by the base station between uplink and downlink for a band occupied by one or more serving cells;

calculate a timing advance feedback for the one or more serving cells based on the timing advance parameter values, a UE-controlled accumulated timing accuracy, and a beginning time for the timing advance feedback, wherein the UE-controlled accumulated timing accuracy indicates a difference between a network-requested timing advance and an actual timing advance that can be achieved by the UE; and

send the timing advance feedback to the base station.

17. The apparatus of claim 16 , wherein the processing circuitry is operative to:

calculate a number of slots impacted by the timing advance feedback based on a subcarrier spacing of an uplink carrier in a frequency layer; and

send the number of slots as the timing advance feedback to the base station.

18. The apparatus of claim 16 , wherein the processing circuitry is operative to:

calculate a number of symbols impacted by the timing advance feedback based on a subcarrier spacing of an uplink carrier in a frequency layer; and

send the number of symbols as the timing advance feedback to the base station.

19. The apparatus of claim 16 , wherein the timing advance feedback is a post-measurement gap (post-MG) time period after a measurement gap before uplink transmission, and the beginning time for the timing advance feedback is an ending time of the measurement gap.

20. A non-transitory computer-readable storage medium comprising instructions which, when executed by a machine, cause the machine to perform a method for wireless communication, the method comprising:

receiving, from a base station, timing advance parameter values which indicate a time difference measured by the base station between uplink and downlink for a band occupied by one or more serving cells;

calculating a timing advance feedback for the one or more serving cells based on the timing advance parameter values, a UE-controlled accumulated timing accuracy, and a beginning time for the timing advance feedback, wherein the UE-controlled accumulated timing accuracy indicates a difference between a network-requested timing advance and an actual timing advance that can be achieved by the UE; and

sending the timing advance feedback to the base station.