Method for small data transmission in power saving state and related devices

1 . A method for small data transmission (SDT) in a power saving state, performed by a user equipment (UE) in a network, the method comprising:

being configured with a SDT resource on a first SDT bandwidth part (BWP) in addition to an initial BWP, wherein the first BWP is a default BWP or an active BWP;

transmitting the SDT on the SDT resource of the first SDT BWP in the power saving state;

receiving a radio resource control (RRC) signaling with wait time;

receiving at least one of a system information (SI) change indication or a public warning system (PWS) indication; and

after a duration of the wait time, switching from the first SDT BWP to a second SDT BWP for receiving at least one of updated SI or PWS information based on the received indication.

2 . The method of claim 1 , wherein the transmitted SDT is random access (RA)-SDT, and the UE is configured by the network with at least one of multiple preamble groups corresponding to different payload sizes of small data on an associated SDT BWP.

3 . The method of claim 1 , wherein the transmitted SDT is configured grant (CG)-SDT, and the UE is configured by the network with at least one of multiple configurations corresponding to different payload sizes of small data for the CG-SDT.

4 . The method of claim 1 , wherein the SI change indication or PWS indication is received on a paging occasion of the first SDT BWP, and

wherein in response to the first SDT BWP being the default SDT BWP, the second SDT BWP is the initial BWP, and

wherein the default SDT BWP does not contain the initial BWP.

5 . The method of claim 1 , wherein the SI change indication or PWS indication is received on physical downlink control channel (PDCCH) or multicast control channel (MCCH) of the first SDT BWP, and

wherein in response to the first SDT BWP being the active SDT BWP, the second SDT BWP is the default SDT BWP,

wherein the active SDT BWP is a separate BWP other than the default SDT BWP; or the active SDT BWP is a wider BWP than the default SDT BWP and provides more SDT resources than the default SDT BWP.

6 . The method of claim 1 , wherein the SI change indication or the PWS indication is transmitted on multicast control channel (MCCH) if the UE has an ability to transmit UL small data and receive multicast service data during the SDT; or the SI change indication or the PWS indication is indicated by a BWP switching information element (IE) of the RRC signaling; or the SI change indication or the PWS indication is indicated by a suspend configuration IE of the RRC signaling.

7 . The method of claim 1 , further comprising:

if at least one SDT related timer is not running on the first SDT BWP, monitoring the at least one of the SI change indication or the PWS indication on a paging occasion.

8 . The method of claim 1 , further comprising:

if at least one SDT related timer is not running on the first SDT BWP, switching from the first SDT BWP to the second SDT BWP for receiving the at least one of the updated SI or the PWS information.

9 . The method of claim 8 , wherein the at least one SDT related timer comprises at least one of a SDT deactivity timer that is associated with SDT paging cycle or paging occasion, or a SDT inactivity timer that is associated with SDT characteristic in the power saving state.

10 . The method of claim 1 , wherein the RRC signaling with the wait time comprises a BWP switching IE or a suspend configuration IE for indicating the SI change indication or the PWS indication.

11 . The method of claim 1 , wherein further comprising:

transmitting an on-demand system information request, wherein the at least one of the updated SI or the PWS information is received via unicast or broadcast in response to the on-demand system information request.

12 . The method of claim 1 , further comprising:

restarting at least one SDT related timer upon reception of the wait time, wherein the updated SI or the PWS information is received based on the at least one SDT related timer.

13 . The method of claim 12 , wherein the updated SI or the PWS information is received on the second SDT BWP.

14 . The method of claim 3 , wherein the transmitted SDT is RA-SDT when CG-SDT resources for the CG-SDT are released.

15 . The method of claim 8 , wherein the at least one SDT related timer comprises a SDT deactivity timer that is associated with SDT paging cycle or paging occasion and a SDT inactivity timer that is associated with SDT characteristic in the power saving state, and wherein if the SDT deactivity timer is not running but the SDT inactivity timer is still running, upon reception of the updated SI or the PWS information, switching from the second SDT BWP back to the first SDT BWP for proceeding the SDT.

16 . The method of claim 9 , wherein the at least one SDT related timer is started on an associated SDT BWP upon an initiation of SDT procedure.

17 . The method of claim 1 , wherein the at least one of the SI change indication or the PWS indication is received by monitoring physical downlink control channel (PDCCH) scrambled by Inactive-RNTI (I-RNTI) or Paging-RNTI (P-RNTI).

18 . A method for small data transmission (SDT) in a power saving state, performed by a base station (BS) in a network, the method comprising:

configuring a user equipment (UE) with a SDT resource on a first SDT bandwidth part (BWP) in addition to an initial BWP, wherein the first BWP is a default BWP or an active BWP;

receiving from the UE in the power saving state the SDT on the SDT resource of the first SDT BWP;

transmitting a radio resource control (RRC) signaling with wait time;

transmitting at least one of a system information (SI) change indication or a public warning system (PWS) indication; and

expecting the UE to switch, after a duration of the wait time, from the first SDT BWP to a second SDT BWP for receiving at least one of updated SI or PWS information based on the transmitted indication.

19 . A user equipment (UE), comprising a memory, a transceiver and a processor coupled to the memory and the transceiver, the processor configured to call and run program instructions stored in a memory, to cooperate with the transceiver to execute the method of claim 1 .

20 . A base station (BS), comprising a memory, a transceiver and a processor coupled to the memory and the transceiver, the processor configured to call and run program instructions stored in a memory, to cooperate with the transceiver to execute the method of claim 18 .