Methods and apparatus of timing/frequency tracking for receiving paging

1. A method, comprising:

performing a timing and frequency tracking based on a first timing/frequency tracking reference signal (RS) at a user equipment (UE) in a beam formed wireless communication system, wherein the first timing/frequency tracking RS is one of a sequence of timing/frequency tracking RSs each transmitted on a beam, and is associated with a beam index;

determining a timing of a paging occasion (PO) window according to an identifier (ID) of the UE, the PO window including a sequence of POs each transmitted on a beam, a same paging downlink control information (DCI) being transmitted multiple times in each of the sequence of POs, the sequence of POs as a whole not overlapping the sequence of timing/frequency tracking RSs as a whole in time domain, each of the sequence of POs being associated with a beam index of the respective beam;

determining, by the UE, a timing for monitoring a first PO within the sequence of POs included in the PO window according to the timing of the PO window and the beam index associated with the first timing/frequency tracking RS, the first PO being associated with the same beam index as the first timing/frequency tracking RS; and

performing a paging monitoring at the first PO that is quasi-co-located (QCLed) with the first timing/frequency tracking RS based on the timing for monitoring the first PO within the sequence of POs included in the PO window.

2. The method of claim 1 , wherein the first timing/frequency tracking RS is a signal synchronization block (SS block).

3. The method of claim 1 , wherein the first timing/frequency tracking RS is an SS block, multiple paging bands are configured for paging transmissions of the same UE and the method further comprises:

determining one of the multiple paging bands configured for paging transmissions of the same UE to be a paging band of the first PO according to an ID of the UE.

4. The method of claim 1 , wherein the first timing/frequency tracking RS is a tracking RS (TRS), the TRS has one of a low-mobility TRS pattern and a high-mobility TRS pattern, the low-mobility TRS pattern and the high-mobility TRS pattern each including RSs distributed over multiple consecutive orthogonal frequency division multiplexing (OFDM) symbols, and the method further comprise:

determining to use the high-mobility TRS pattern when an indication of a high-mobility scenario is received from a BS.

5. The method of claim 4 , wherein the low-mobility TRS pattern includes at least two OFDM symbols, the high-mobility TRS pattern includes at least three OFDM symbols, and the high-mobility scenario corresponds to a high-speed rail in a cell coverage.

6. The method of claim 1 , further comprising:

determining a presence or absence of a paging DCI according to a paging indication carried by the first PO, the first PO and the respective paging DCI being located in different slots.

7. The method of claim 1 , further comprising:

determining an RS source for performing the timing and frequency tracking, the RS source being SS blocks, tracking RSs (TRSs), or a combination of SS blocks and TRSs.

8. The method of claim 7 , further comprising:

determining the RS source to be the SS blocks when a period for transmitting the SS blocks is below a threshold value; and

determining the RS source to be the TRSs when the period for transmitting the SS blocks is above the threshold value.

9. The method of claim 7 , further comprising:

determining the RS source to be the SS blocks when an interval between the first PO and an adjacent SS block is below a threshold value, the adjacent SS block associated with the same beam index as the first PO; and

determining the RS source to be the TRSs when a gap between the first PO and the adjacent SS block is above the threshold value.

10. The method of claim 1 , further comprising:

selecting the first timing/frequency RS from the sequence of timing/frequency RSs according to measurement results, the first timing/frequency RS having a highest quality.

11. A mobile device, comprising circuitry configured to:

perform a timing and frequency tracking based on a first timing/frequency tracking reference signal (RS) in a beam formed wireless communication system, wherein the first timing/frequency tracking RS is one of a sequence of timing/frequency tracking RSs each transmitted on a beam, and is associated with a beam index;

determine a timing of a paging occasion (PO) window according to an identifier (ID) of the mobile device, the PO window including a sequence of POs each transmitted on a beam, a same paging downlink control information (DCI) being transmitted multiple times in each of the sequence of POs, the sequence of POs as a whole not overlapping the sequence of timing/frequency tracking RSs as a whole in time domain, each of the sequence of POs being associated with a beam index of the respective beam;

determine a timing for monitoring a first PO within the sequence of POs included in the PO window according to the timing of the PO window and the beam index associated with the first timing/frequency tracking RS, the first PO being associated with the same beam index as the first timing/frequency tracking RS; and

perform a paging monitoring at the first PO that is quasi-co-located (QCLed) with the first timing/frequency tracking RS based on the timing for monitoring the first PO within the sequence of POs included in the PO window.

12. A non-transitory computer-readable medium storing instructions, when executed by a processor, cause the processor to perform a method, the method comprising:

performing a timing and frequency tracking based on a first timing/frequency tracking reference signal (RS) at a user equipment (UE) in a beam formed wireless communication system, wherein the first timing/frequency tracking RS is one of a sequence of timing/frequency tracking RSs each transmitted on a beam, and is associated with a beam index;

determining a timing of a paging occasion (PO) window according to an identifier (ID) of the UE, the PO window including a sequence of POs each transmitted on a beam, a same paging downlink control information (DCI) being transmitted multiple times in each of the sequence of POs, the sequence of POs as a whole not overlapping the sequence of timing/frequency tracking RSs as a whole in time domain, each of the sequence of POs being associated with a beam index of the respective beam;

determining, at the UE, a timing for monitoring a first PO within the sequence of POs included in the PO window according to the timing of the PO window and the beam index associated with the first timing/frequency tracking RS, the first PO being associated with the same beam index as the first timing/frequency tracking RS; and

performing a paging monitoring at the first PO that is quasi-co-located (QCLed) with the first timing/frequency tracking RS based on the timing for monitoring the first PO within the sequence of POs included in the PO window.

13. The non-transitory computer-readable medium of claim 12 , wherein the first timing/frequency tracking RS is a signal synchronization block (SS block).

14. The non-transitory computer-readable medium of claim 12 , wherein the first timing/frequency tracking RS is an SS block, multiple paging bands are configured for paging transmissions of the same UE, and the method further comprises:

determining one of the multiple paging bands configured for paging transmissions of the same UE to be a paging band of the first PO according to an ID of the UE.

15. The non-transitory computer-readable medium of claim 12 , wherein the first timing/frequency tracking RS is a tracking RS (TRS), the TRS has one of a low-mobility TRS pattern and a high-mobility TRS pattern, the low-mobility TRS pattern and the high-mobility TRS pattern each including RSs distributed over multiple consecutive orthogonal frequency division multiplexing (OFDM) symbols, and the method further comprise:

determining to use the high-mobility TRS pattern when an indication of a high-mobility scenario is received from a BS.

16. The non-transitory computer-readable medium of claim 15 , wherein the low-mobility TRS pattern includes at least two OFDM symbols, the high-mobility TRS pattern includes at least three OFDM symbols, and the high-mobility scenario corresponds to a high-speed rail in a cell coverage.

17. The non-transitory computer-readable medium of claim 12 , wherein the method further comprises:

determining a presence or absence of a paging DCI according to a paging indication carried by the first PO, the first PO and the respective paging DCI being located in different slots.

18. The non-transitory computer-readable medium of claim 12 , wherein the method further comprises:

determining an RS source for performing the timing and frequency tracking, the RS source being SS blocks, tracking RSs (TRSs), or a combination of SS blocks and TRSs.

19. The non-transitory computer-readable medium of claim 18 , wherein the method further comprises:

determining the RS source to be the SS blocks when a period for transmitting the SS blocks is below a threshold value; and

determining the RS source to be the TRSs when the period for transmitting the SS blocks is above the threshold value.

20. The non-transitory computer-readable medium of claim 18 , wherein the method further comprises:

determining the RS source to be the SS blocks when an interval between the first PO and an adjacent SS block is below a threshold value, the adjacent SS block associated with the same beam index as the first PO; and

determining the RS source to be the TRSs when a gap between the first PO and the adjacent SS block is above the threshold value.