WO2022104589A1

WO2022104589A1 - Method and apparatus for small data transmission

Info

Publication number: WO2022104589A1
Application number: PCT/CN2020/129755
Authority: WO
Inventors: Ran YUE; Lianhai WU; Jie Shi; Haiming Wang; Yu Zhang
Original assignee: Lenovo (Beijing) Limited
Priority date: 2020-11-18
Filing date: 2020-11-18
Publication date: 2022-05-27

Abstract

Embodiments of the present application are directed to a method and apparatus for small data transmission. In an embodiment of the present application, the method includes: receiving listen before talk (LBT) failure indications for small data transmission (SDT); triggering consistent LBT failure for a first uplink (UL) resource for SDT in response to a number of the LBT failure indications exceeding or being equal to a predetermined threshold within a predetermined time duration for the first UL resource for SDT; and performing a recovery procedure by switching the SDT from the first UL resource to a second UL resource in response to the consistent LBT failure for the first UL resource for SDT being triggered.

Description

METHOD AND APPARATUS FOR SMALL DATA TRANSMISSION

TECHNICAL FIELD

Embodiments of the present application generally relate to wireless communication technology, especially to a method and apparatus for small data transmission (SDT) , e.g., for 5G new radio on unlicensed spectrum (NR-U) uplink transmission.

BACKGROUND

A base station (BS) and a user equipment (UE) may operate in both licensed and unlicensed spectrum. Listen before talk (LBT) is a channel access technique used for transmission on an unlicensed spectrum. For transmission on unlicensed spectrum, in order to achieve fair coexistence with other wireless systems, a LBT procedure is required to be performed before a transmitter (e.g., a BS or a UE) can start a transmission on an unlicensed spectrum.

LBT is executed based on performing energy detection on a certain channel. Only when a LBT procedure generates a success result, the transmitter can start the transmission on the channel and occupy the channel up to a certain channel occupancy time; otherwise, the transmitter cannot start the transmission and continue performing LBT until a LBT procedure generates a successful result.

Small data transmission (SDT) may be performed when a UE is in radio resource control (RRC) _INACTIVE state or in idle state. However, there is no discussion on a mechanism for handling consistent LBT failure when SDT is performed.

SUMMARY OF THE APPLICATION

Embodiments of the present application provide a method and apparatus for data transmission, e.g., for 5G new radio on NR-U uplink transmission.

An embodiment of the present application provides a method. The method may include: receiving listen before talk (LBT) failure indications for small data transmission (SDT) ; triggering consistent LBT failure for a first uplink (UL) resource for SDT in response to a number of the LBT failure indications exceeding or being equal to a predetermined threshold within a predetermined time duration for the first UL resource for SDT; and performing a recovery procedure by switching the SDT from the first UL resource to a second UL resource in response to the consistent LBT failure for the first UL resource for SDT being triggered.

In an embodiment of the present application, performing the recovery procedure further comprises: initiating a random access channel (RACH) procedure if there is no UL resource available for the SDT or any UL transmission.

In an embodiment of the present application, the method may further include: receiving configuration information for the consistent LBT failure for SDT by a system broadcast message or radio resource control (RRC) signaling, wherein the configuration information indicates at least one of the predetermined threshold corresponding to a maximum number of the LBT failure indications received and the predetermined time duration corresponding to time duration for monitoring LBT failure for SDT.

In an embodiment of the present application, the first UL resource is one of the following: a UL pre-configured resource for SDT; a physical uplink shared channel (PUSCH) resource and PRACH resource during a random access channel (RACH) procedure for SDT; and any other UL resource for SDT.

In an embodiment of the present application, the method may further include at least one of: detecting the consistent LBT failure per UL pre-configured resource for SDT by counting the LBT failure indications for all UL transmissions; detecting the consistent LBT failure per UL bandwidth part (BWP) for SDT by counting the LBT failure indications for all UL transmissions; and detecting the consistent LBT failure per physical random access channel (PRACH) index, per MsgA PUSCH configuration, or Msg3 PUSCH configuration by counting the LBT failure indications for all UL transmissions.

In an embodiment of the present application, each of the LBT failure indications comprises information indicating the LBT failure indication is for which UL pre-configured resource, which UL BWP, which PRACH index, which MsgA PUSCH configuration, or which Msg3 PUSCH configuration.

In an embodiment of the present application, the consistent LBT failure is triggered for UL pre-configured resource for SDT, an UL BWP, PRACH index, MsgA PUSCH configuration, or Msg3 PUSCH configuration, when the counted number of the LBT failure indications exceeds or is equal to the predetermined threshold within the predetermined time duration for SDT.

In an embodiment of the present application, switching the SDT from the first UL resource to the second UL resource comprises: in the case of a plurality of UL resources for SDT being configured or available and information about which UL BWP the UL resources for SDT belong to being not configured, selecting the second UL resource for switching is in an order of priority for switching: each UL pre-configured resource for SDT which has not been indicated LBT failure, each MsgA resource including PRACH resource and MsgA PUSCH resource during a 2-step RACH procedure for SDT which has not been indicated LBT failure, each PRACH resource during a RACH procedure for SDT which has not been indicated LBT failure, and each PRACH resource during a RACH procedure not for SDT which has not been indicated LBT failure.

In an embodiment of the present application, switching the SDT from the first UL resource to the second UL resource comprises: in the case of a plurality of UL resources for SDT being configured or available and information about which UL BWP the UL resources for SDT belong to being configured, selecting the second UL resource for switching is in an order of priority for switching: each UL pre-configured resource for SDT on a same BWP as the first UL resource which has not been indicated LBT failure, each MsgA resource including PRACH resource and MsgA PUSCH resource during a 2-step RACH procedure for SDT on a same BWP as the first UL resource which has not been indicated LBT failure, each PRACH resource during a RACH procedure for SDT on a same BWP as the first UL resource which has not been indicated LBT failure, each UL pre-configured resource for SDT on another BWP which has not been indicated LBT failure, each MsgA resource including PRACH resource and MsgA PUSCH resource during a 2-step RACH procedure for SDT on another BWP which has not been indicated LBT failure, each PRACH resource during a RACH procedure for SDT on another BWP which has not been indicated LBT failure, each PRACH resource during a RACH procedure not for SDT on an BWP which has not been indicated LBT failure.

In an embodiment of the present application, the method may further include: in the case that only a first UL pre-configured resource on a first UL BWP is configured and activated for SDT and the consistent LBT failure for the first UL pre-configured resource for SDT is triggered, autonomously switching the SDT from the first UL pre-configured resource to a second UL pre-configured resource on a second UL BWP which has not been indicated LBT failure.

In an embodiment of the present application, the method may further include: in the case that there is no the second UL pre-configured resource on the second UL BWP, autonomously switching the SDT from the first UL pre-configured resource to a third UL BWP with random access (RA) configuration which has not been indicated LBT failure.

In an embodiment of the present application, the method may further include: in the case that a plurality of UL pre-configured resources on a first UL BWP are configured for SDT and at least one UL pre-configured resource of the plurality of UL pre-configured resources is activated and the consistent LBT failure for each of the plurality of UL pre-configured resources for SDT on the first BWP is triggered, autonomously switching the SDT to a second UL pre-configured resource on a second UL BWP with or without RA configuration which has not been indicated LBT failure. It could be up to the UE implementation to switch the SDT to the second UL pre-configured resource on the second UL BWP with or without RA configuration which has not been indicated LBT failure, or switch the SDT to the second UL pre-configured resource on the second UL BWP with RA configuration prior to the second UL BWP without RA configuration which has not been indicated LBT failure.

In an embodiment of the present application, the method may further include: in the case that there is no the second UL pre-configured resource on the second UL BWP, autonomously switching the SDT to a third UL BWP with RA configuration which has not been indicated LBT failure.

In an embodiment of the present application, the method may further include: initiating UL pre-configured resource based SDT or a RACH based SDT or a random access procedure.

In an embodiment of the present application, the method may further include: indicating a consistent LBT failure for SDT to upper layers when there is no the second UL resource for switching.

In an embodiment of the present application, the method may further include: canceling the triggered consistent LBT failure if a MAC PDU is transmitted and LBT failure indication is not received and this MAC PDU includes the LBT failure indication or this MAC PDU is transmitted on the second UL resource, or if consistent LBT failure is triggered and not cancelled and a random access procedure is considered successfully completed, or a preamble or a MAC PDU in a random access procedure is transmitted, or if configuration information for the consistent LBT failure for SDT is reconfigured by upper layers.

Another embodiment of the present application provides a method. The method may include: transmitting configuration information for monitoring consistent listen before talk (LBT) failure for small data transmission (SDT) ; and receiving uplink transmission for SDT; wherein the configuration information comprises at least one of a maximum number of LBT failure indications for SDT that may be received by a user equipment (UE) and time duration for monitoring LBT failure for SDT.

In an embodiment of the present application, the configuration information is transmitted via a system broadcast message or radio resource control (RRC) signaling.

Another embodiment of the present application provides an apparatus. The apparatus may include at least one non-transitory computer-readable medium having computer executable instructions stored therein; at least one receiver; at least one transmitter; and at least one processor coupled to the at least one non-transitory computer-readable medium, the at least one receiver and the at least one transmitter. The computer executable instructions are programmed to implement the above method with the at least one receiver, the at least one transmitter and the at least one processor.

Embodiments of the present application provide a mechanism for handling consistent LBT failure when SDT is performed which can detect consistent LBT failure and recovery from the consistent LBT failure in SDT case.

BRIEF DESCRIPTION OF THE DRAWINGS

In order to describe the manner in which advantages and features of the application can be obtained, a description of the application is rendered by reference to specific embodiments thereof, which are illustrated in the appended drawings. These drawings depict only example embodiments of the application and are not therefore to be considered limiting of its scope.

FIG. 1 illustrates a wireless communication system according to some embodiments of the present application;

FIG. 2 illustrates a flow chart of a method for handling consistent LBT failure during small data transmission according to some embodiments of the present application;

FIG. 3 illustrates an apparatus according to some embodiments of the present application; and

FIG. 4 illustrates another apparatus according to some other embodiments of the present application.

DETAILED DESCRIPTION

The detailed description of the appended drawings is intended as a description of preferred embodiments of the present application and is not intended to represent the only form in which the present application may be practiced. It should be understood that the same or equivalent functions may be accomplished by different embodiments that are intended to be encompassed within the spirit and scope of the present application.

Reference will now be made in detail to some embodiments of the present application, examples of which are illustrated in the accompanying drawings.

FIG. 1 illustrates a wireless communication system according to some embodiments of the present application.

As shown in FIG. 1, the wireless communication system can include at least one base station (BS) , at least one UE, and a core network (CN) node. Although a specific number of BSs and UEs, e.g., a BS (e.g., BS 102) and a UE (UE 101) are depicted in FIG. 1, one skilled in the art will recognize that any number of the BSs and UEs may be included in the wireless communication system. As shown in FIG. 1, the BS 102 may be distributed over a geographic region and may communicate with the CN node 103 via an interface.

The UE 101 may be a computing device, such as a desktop computer, a laptop computer, a personal digital assistant (PDA) , a tablet computer, a smart television (e.g., a television connected to the Internet) , a set-top box, a game console, a security system (including security cameras) , a vehicle on-board computer, a network device (e.g., router, switch, and modem) , or the like. According to an embodiment of the present application, the UE 101 may be a portable wireless communication device, a smart phone, a cellular telephone, a flip phone, a device having a subscriber identity module, a personal computer, a selective call receiver, or any other device that is capable of sending and receiving communication signals on a wireless network. In some embodiments of the present application, the UE 201 may be a wearable device, such as a smart watch, a fitness band, an optical head-mounted display, or the like. Moreover, the UE 101 may be referred to as a subscriber unit, a mobile, a mobile station, a user, a terminal, a mobile terminal, a wireless terminal, a fixed terminal, a subscriber station, a user terminal, or a device, or described using other terminology used in the art.

The BS 102 may communicate with a CN node 103 via an interface. In some embodiments of the present application, the BS 102 may also be referred to as an access point, an access terminal, a base, a base unit, a macro cell, a Node-B, an evolved Node B (eNB) , a gNB, a Home Node-B, a relay node, or a device, or described using other terminology used in the art. The BS 102 is generally part of a radio access network that may include one or more controllers communicably coupled to one or more corresponding BS (s) .

In an example, the CN node 103 can be a mobility management entity (MME) or a serving gateway (S-GW) . In another embodiment of the present application, the CN node 103 may include a mobility management function (AMF) or a user plane function (UPF) .

The wireless communication system may be compatible with any type of network that is capable of sending and receiving wireless communication signals. For example, the wireless communication system 100 is compatible with a wireless communication network, a cellular telephone network, a time division multiple access (TDMA) -based network, a code division multiple access (CDMA) -based network, an orthogonal frequency division multiple access (OFDMA) -based network, a LTE network, a 3rd generation partnership project (3GPP) -based network, a 3GPP 5G network, a satellite communications network, a high altitude platform network, and/or other communications networks.

In some embodiments of the present application, the wireless communication system is compatible with the 5G new radio of the 3GPP protocol, wherein BS 102 transmits data using an OFDM modulation scheme on the downlink (DL) and UE 101 transmit data on the uplink (UL) using a single-carrier frequency division multiple access (SC-FDMA) or OFDM scheme. More generally, however, the wireless communication system may implement some other open or proprietary communication protocols, for example, WiMAX, WiFi, among other protocols.

In some embodiments of the present application, the BS 102 may communicate using other communication protocols, such as the IEEE 802.11 family of wireless communication protocols. Further, in some embodiments of the present application, the BS 102 may communicate over licensed spectrums, whereas in other embodiments the BS 102 may communicate over unlicensed spectrums. Embodiments of the present application are not intended to be limited to the implementation of any particular wireless communication system architecture or protocol. In yet some embodiments of the present application, the BS 102 may communicate with UE 101 using the 3GPP 5G protocols.

In an example, the UE 101 is in RRC_IDLE mode or in RRC_INACTIVE state. When performing small data transmission, the UE 101 connects to the BS 102, and the BS 102 transmits the small data to the CN node 103 via the interface.

Herein, the data transmission or small data transmission (SDT) may mean that a UE in inactive mode or idle mode could transmit the data to the network side (or network) , or receive the data from the network side. The data transmission may include at least one of an uplink (UL) data transmission and downlink (DL) data transmission. After the completion of the data transmission, the inactive or idle UE may receive a suspend message or release message from the network and then go back to the inactive or idle mode. In some other embodiments of the present application, after the completion of the data transmission, the inactive or idle UE may receive a suspend message or release message from the network and the UE still stay in inactive or idle mode during the data transmission procedure. In some embodiments of the present application, the suspend message or release message is an RRC message. In some embodiments of the present application, the data size in such data transmission may be no larger than the maximum transport block (TB) size that can be applied in one transmission, as defined in standard (s) or protocol (s) . Small data transmission is one of such scenarios.

Currently, the work item (WID) on small data transmission (SDT) in RRC_INACTIVE state is as follows:

- For the RRC_INACTIVE state:

○ UL small data transmissions for RACH-based schemes (i.e. 2-step and 4-step RACH) :

■ General procedure to enable UP data transmission for small data packets from INACTIVE state (e.g. using MSGA or MSG3) [RAN2]

■ Enable flexible payload sizes larger than the Rel-16 CCCH message size that is possible currently for INACTIVE state for MSGA and MSG3 to support UP data transmission in UL (actual payload size can be up to network configuration) [RAN2]

■ Context fetch and data forwarding (with and without anchor relocation) in INACTIVE state for RACH-based solutions [RAN2, RAN3]

○ Transmission of UL data on pre-configured PUSCH resources (i.e. reusing the configured grant type 1) -when TA is valid

■ General procedure for small data transmission over configured grant type 1 resources from INACTIVE state [RAN2]

■ Configuration of the configured grant type1 resources for small data transmission in UL for INACTIVE state [RAN2]

No new RRC state should be introduced in this WID. Transmission of small data in UL, subsequent transmission of small data in UL and DL and the state transition decisions should be under network control. Focus of the WID should be on licensed carriers and the solutions can be reused for NR-U if applicable.

As illustrated in the WID, the solutions on licensed carriers can be reused for NR-U if applicable.

For the connected state UEs, it was decided to apply a separate mechanism ‘consistent LBT failure recovery’ to handle the case when UL LBT fails successively which is beneficial from the perspective of transmission performance. The LBT failure detection and recovery procedure of the mechanism ‘consistent LBT failure recovery’ is described in 3GPP TS 38.321 as follows:

...

For each activated Serving Cell configured with lbt-FailureRecoveryConfig, the MAC entity shall:

1> if LBT failure indication has been received from lower layers:

2> start or restart the lbt-FailureDetectionTimer;

2> increment LBT_COUNTER by 1;

2> if LBT_COUNTER >= lbt-FailureInstanceMaxCount:

3> trigger consistent LBT failure for the active UL BWP in this Serving Cell;

3> if this Serving Cell is the SpCell:

4> if consistent LBT failure has been triggered in all UL BWPs configured with PRACH occasions on same carrier in this Serving Cell:

5> indicate consistent LBT failure to upper layers.

4> else:

5> stop any ongoing Random Access procedure in this Serving Cell;

5> switch the active UL BWP to an UL BWP, on same carrier in this Serving Cell, configured with PRACH occasion and for which consistent LBT failure has not been triggered;

5> initiate a Random Access Procedure (as specified in clause 5.1.1) .

...

However, there is no related discussion on the SDT in RRC_INACTIVE state. A mechanism for handling consistent LBT failure when the SDT is performed will be discussed in the following description of the present application. For example, how to detect a (or consistent) LBT failure in SDT case in RRC_INACTIVE state and how to recover from the consistent LBT failure in SDT case.

In an aspect, as illustrated in the consistent LBT failure recovery in 3GPP TS 38.321, for the connected state UEs, the consistent LBT failure recovery is configured per serving cell and the consistent LBT failure is detected per UL BWP.

If the LBT failure recovery is not supported by SDT, the UL data will not be transmitted and the network cannot detect the problem of consistent LBT failure in time, then the potential reconfiguration to another resource will not be triggered when consistent LBT failure occurs. On the other hand, the SDT can only be performed on the pre-configured UL resource (s) or the granted RACH resource (in 2-step RACH procedure or 4-step RACH procedure) but not on the whole BWP, thus the LBT failure detection on the whole BWP seems not necessary during SDT. Therefore, it is necessary to optimize the procedure with a LBT failure recovery mechanism for SDT. Therefore, how to detect the LBT failure and configure the related parameters will be discussed in the following description.

In another aspect, the consistent LBT failure for all UL BWP (s) with random access (RA) configuration will lead to radio link failure (RLF) and RRC re-establishment eventually. It is beneficial to avoid data loss and latency introduced by RRC re-establishment if a LBT failure can be recovered before RLF. In the existing technique, the LBT failure is recovered by initializing a RACH or a PUSCH transmission.

There is the similar case to SDT. And considering the following multiple SDTs, the reconfiguration could be needed since the consistent LBT failure implies the resources which can do SDT are busy and potentially consistently busy. Therefore, it is necessary to optimize the recovery procedure from the LBT failure for SDT. Therefore, how to recover from the consistent LBT failure in SDT case will be also discussed in the following description of the present application.

FIG. 2 illustrates a flow chart of a method for handling consistent LBT failure during small data transmission according to some embodiments of the present application. The method in FIG. 2 is performed between a BS (e.g., BS 102 in FIG. 1) and a UE (e.g., UE 101 in FIG. 1) .

As shown in FIG. 2, in step 210, the BS may transmit configuration information for the consistent LBT failure for SDT.

For example, the configuration information for the consistent LBT failure for SDT (such as, lbt-FailureRecoveryConfig-SDT) may be transmitted by system broadcast message or RRC signaling. In an example, the configuration information for the consistent LBT failure for SDT may be configured with the SDT configuration. The configuration information may at least include the following parameters: the maximum number of LBT failure indications received from lower layers for consistent LBT failure detection when doing SDT (such as, lbt-FailureInstanceMaxCount-SDT) and the time duration for consistent LBT failure detection when doing SDT (such as, lbt-FailureDetectionTimer-SDT) . These parameters can be used for RACH based SDT and/or pre-configured UL resource based (configured grant (CG) type 1 based) SDT for the consistent LBT failure detection.

It should be understood that in some other embodiments of the present application, step 210 may not be performed if the configuration information has been transmitted to the UE in advance, or predefined in the specification.

In the embodiments of the present application, the consistent LBT failure for SDT may be detected per UL resource for SDT by counting LBT failure indications. In step 220, the UE may receive LBT failure indications for SDT. For example, the lower layer (such as physical layer) of the UE may detect a LBT failure for SDT and indicate the LBT failure for SDT to MAC layer of the UE.

In step 230, the UE may trigger the consistent LBT failure for the UL resource for SDT in response to a number of the LBT failure indications exceeding or being equal to a predetermined threshold within predetermined time duration for the UL resource for SDT. The predetermined threshold may correspond to the maximum number of the LBT failure indications (lbt-FailureInstanceMaxCount-SDT) and the predetermined time duration may correspond to time duration for monitoring LBT failure for SDT (lbt-FailureDetectionTimer-SDT) .

A counter for LBT failure indication for SDT (for example, LBT_COUNTER_SDT) may be configured to be set to 0 initially and to counter the number of the LBT failure indications. The counter can be configured per UL resource, per BWP, or per serving cell.

For example, when the UE receives the configured maximum number of LBT failure indications within the configured time duration for the UL resource, the consistent LBT failure is triggered for the UL resource for SDT. The maximum number of LBT failure indications and the time duration for the UL resource are configured in the configuration information for the consistent LBT failure for SDT, such as, by network (NW) via RRC layer.

The UL resource may be a UL pre-configured resource for SDT, a physical uplink shared channel (PUSCH) resource and PRACH resource during a RACH procedure for SDT, or any other UL resource for SDT. The RACH procedure for SDT may include 2-step RACH procedure or 4-step RACH procedure.

In the embodiments of the present application, the lower layer of the UE may detect LBT failure for all UL transmissions per UL pre-configured resource, per UL bandwidth part (BWP) , or per physical random access channel (PRACH) index, per MsgA PUSCH configuration, or Msg3 PUSCH configuration, and indicate each LBT failure to the MAC entity.

Accordingly, each of the LBT failure indications may include information indicating the LBT failure indication is for which UL pre-configured resource, which UL BWP, which PRACH index (or PRACH configuration index) , which MsgA PUSCH configuration, or which Msg3 PUSCH allocation. For example, if the LBT failure is indicated per UL pre-configured resource, the indication should include that the LBT failure indication is for which UL pre-configured resource. In another example, if the LBT failure is indicated as legacy (for example, by 1 bit) , a note may be added, for example, the LBT on multi-subband should base on the sequence of subband frequency from low to high, or some pre-configured sequence which can be mapped to the UL pre-configured resource, in order to indicate the LBT failure is for which subband , or the LBT failure is for which UL pre-configured resource. Thus, the note is to provide a specific indication to the counter of LBT failure.

After the lower layer of the UE indicates the LBT failure to the MAC entity, the MAC entity may detect the consistent LBT failure by counting the LBT failure indications for all UL transmissions. In particular, the MAC entity may detect the consistent LBT failure per UL pre-configured resource for SDT by counting the LBT failure indications for all UL transmissions; detect the consistent LBT failure per UL bandwidth part (BWP) for SDT by counting the LBT failure indications for all UL transmissions; or detect the consistent LBT failure per physical random access channel (PRACH) index, per MsgA PUSCH configuration, or Msg3 PUSCH configuration by counting the LBT failure indications for all UL transmissions.

For each activated serving cell configured with LBT failure recovery for SDT, if LBT failure indication has been received from lower layers, the MAC entity of the UE will start or restart the lbt-FailureDetectionTimer-SDT, increment LBT_COUNTER_SDT by 1, and if LBT_COUNTER_SDT >=lbt-FailureInstanceMaxCount-SDT, the MAC entity will trigger consistent LBT failure for the CG type1 resource configured for SDT, for active UL BWP, for PRACH configuration Index, or for MsgA PUSCH configuration in this serving cell. If the LBT failure indication corresponds to multiple UL transmission resources, the counter LBT_COUNTER_SDT for each of the resource may be increased by 1.

In step 240, the UE may perform a recovery procedure in response to the consistent LBT failure for the UL resource for SDT being triggered.

In some embodiments of the present application, the UE may perform a recovery procedure by switching the SDT from the UL resource to another UL resource. However, if there is no UL resource available for the SDT or any UL transmission, the UE may initiate a random access channel (RACH) procedure.

When the consistent LBT failure for SDT is triggered, the priority of the switching among the UL resources for SDT to recover from the consistent LBT failure will be described in the following:

In an embodiment, if there are a plurality of UL resources for SDT being configured or available and information about which UL BWP the UL resources for SDT belong to is not configured, the MAC entity of the UE may select the UL resource for switching is in an order of priority for switching: each UL pre-configured resource for SDT which has not been indicated LBT failure, each MsgA resource including PRACH resource and MsgA PUSCH resource during a 2-step RACH procedure for SDT which has not been indicated LBT failure, each PRACH resource during a RACH procedure (4-step RACH procedure) for SDT which has not been indicated LBT failure, and each PRACH resource during a RACH procedure not for SDT which has not been indicated LBT failure. The order of priority for switching can be specified by 3GPP specification or configured/broadcasted by the network (NW) .

In another embodiment, if there are a plurality of UL resources for SDT being configured or available and information about which UL BWP the UL resources for SDT belong to is not configured, the MAC entity of the UE may select the UL resource for SDT for switching from any one of the following UL resources: each UL pre-configured resource for SDT which has not been indicated LBT failure, each MsgA resource including PRACH resource and MsgA PUSCH resource during a 2-step RACH procedure for SDT which has not been indicated LBT failure, each PRACH resource during a RACH procedure (4-step RACH procedure) for SDT which has not been indicated LBT failure, and each PRACH resource during a RACH procedure not for SDT which has not been indicated LBT failure. That is, in this embodiment, the UL resources for SDT for switching do not need to be sorted.

In another embodiment, if there are a plurality of UL resources for SDT being configured or available and information about which UL BWP the UL resources for SDT belong to is configured, the MAC entity of the UE may select the second UL resource for switching is in an order of priority for switching: each UL pre-configured resource for SDT on the same BWP which has not been indicated LBT failure, each MsgA resource including PRACH resource and MsgA PUSCH resource during a 2-step RACH procedure for SDT on the same BWP which has not been indicated LBT failure, each PRACH resource during a RACH procedure (4-step RACH procedure) for SDT on the same BWP which has not been indicated LBT failure, each UL pre-configured resource for SDT on another BWP which has not been indicated LBT failure, each MsgA resource including PRACH resource and MsgA PUSCH resource during a 2-step RACH procedure for SDT on another BWP which has not been indicated LBT failure, each PRACH resource during a RACH procedure (4-step RACH procedure) for SDT on another BWP which has not been indicated LBT failure, each PRACH resource during a RACH procedure not for SDT on an BWP which has not been indicated LBT failure. The same switching priority can be repeated on another serving cell. The order of priority for switching can be specified by 3GPP specification or configured/broadcasted by the NW.

In another embodiment, if there are a plurality of UL resources for SDT being configured or available and information about which UL BWP the UL resources for SDT belong to is configured, the MAC entity of the UE may select the UL resource for SDT for switching from any one of the following UL resources: each UL pre-configured resource for SDT on the same BWP which has not been indicated LBT failure, each MsgA resource including PRACH resource and MsgA PUSCH resource during a 2-step RACH procedure for SDT on the same BWP which has not been indicated LBT failure, each PRACH resource during a RACH procedure (4-step RACH procedure) for SDT on the same BWP which has not been indicated LBT failure, each UL pre-configured resource for SDT on another BWP which has not been indicated LBT failure, each MsgA resource including PRACH resource and MsgA PUSCH resource during a 2-step RACH procedure for SDT on another BWP which has not been indicated LBT failure, each PRACH resource during a RACH procedure (4-step RACH procedure) for SDT on another BWP which has not been indicated LBT failure, each PRACH resource during a RACH procedure not for SDT on an BWP which has not been indicated LBT failure. That is, in this embodiment, the UL resources for SDT for switching do not need to be sorted.

For switching the SDT from the UL resource to another UL resource, some specific examples are described in the following for persons skilled in the art to understand the above embodiments of the present application more clearly.

For example, in the case that only a first UL pre-configured resource (e.g. pre-configured CG type1 resource) on a first UL BWP is configured and activated for SDT and the consistent LBT failure for the first UL pre-configured resource for SDT is triggered, the MAC entity of the UE autonomously switches the SDT from the first UL pre-configured resource to a second UL pre-configured resource on a second UL BWP which has not been indicated LBT failure. Furthermore, in the case that there is no the second UL pre-configured resource on the second UL BWP, the MAC entity of the UE autonomously switches the SDT from the first UL pre-configured resource to a third UL BWP with random access (RA) configuration which has not been indicated LBT failure. It could be up to the UE implementation to switch the SDT to the second UL pre-configured resource on the second UL BWP with or without RA configuration which has not been indicated LBT failure, or switch the SDT to the second UL pre-configured resource on the second UL BWP with RA configuration prior to the second UL BWP without RA configuration which has not been indicated LBT failure.

In another example, in the case that a plurality of UL pre-configured resources on a first UL BWP are configured for SDT and at least one UL pre-configured resource of the plurality of UL pre-configured resources is activated and the consistent LBT failure for each of the plurality of UL pre-configured resources for SDT on the first BWP is triggered, the MAC entity of the UE autonomously switches the SDT to a second UL pre-configured resource on a second UL BWP with or without RA configuration which has not been indicated LBT failure. Furthermore, in the case that there is no the second UL pre-configured resource on the second UL BWP, the MAC entity of the UE autonomously switches the SDT to a third UL BWP with RA configuration which has not been indicated LBT failure.

In another example, in the case that the consistent LBT failure for the pre-configured CG type1 resource is triggered, the MAC entity of the UE autonomously switches the SDT from the pre-configured CG type1 resource to another pre-configured CG type1 resource, if configured.

In another example, in the case that the consistent LBT failure for the pre-configured CG type1 resource is triggered, the MAC entity of the UE autonomously switches the SDT from the pre-configured CG type1 resource to an UL BWP, on same carrier in this serving cell, configured with PRACH occasion for SDT and for which consistent LBT failure has not been triggered.

In another example, in the case that the consistent LBT failure for the pre-configured CG type1 resource is triggered, the MAC entity of the UE autonomously switches the SDT from the pre-configured CG type1 resource to an UL BWP, on same carrier in this serving cell, configured with PRACH occasion and for which consistent LBT failure has not been triggered.

In another example, in the case that the consistent LBT failure for the PRACH configuration index and/or the MsgA PUSCH configuration is triggered, the MAC entity of the UE autonomously switches the SDT from the PRACH configuration index and/or the MsgA PUSCH configuration to an UL BWP, on same carrier in this serving cell, configured with PRACH occasion for SDT and for which consistent LBT failure has not been triggered.

In another example, in the case that the consistent LBT failure for the PRACH configuration index and/or the MsgA PUSCH configuration is triggered, the MAC entity of the UE autonomously switches the SDT from the PRACH configuration index and/or the MsgA PUSCH configuration to an UL BWP, on same carrier in this serving cell, configured with PRACH occasion and for which consistent LBT failure has not been triggered.

In another example, in the case that the consistent LBT failure for the active UL BWP for SDT is triggered, the MAC entity of the UE autonomously switches the SDT from the active UL BWP to an UL BWP, on same carrier in this serving cell, configured with PRACH occasion for SDT and for which consistent LBT failure has not been triggered, or to an UL BWP, on same carrier in this serving cell, configured with PRACH occasion and for which consistent LBT failure has not been triggered.

In another example, in the case that the consistent LBT failure for at least one MsgA resource including PRACH resource and MsgA PUSCH resource during a 2-step RACH procedure for SDT or PRACH resource during a RACH procedure for SDT on a first UL BWP or Msg3 PUSCH resource during a RACH procedure for SDT on a first UL BWP is triggered, the MAC entity of the UE autonomously switches the SDT to a UL pre-configured resource on a second UL BWP with or without RA configuration which has not been indicated LBT failure.

After selecting the UL resource for SDT for switching, the UE may initiate the corresponding UL transmission, for example, UL pre-configured resource based SDT or a RACH based SDT or a random access procedure, by switching the SDT from the UL resource to the selected UL resource. Accordingly, the BS may receive the UL transmission for SDT.

In another embodiment, when there is no the UL resource for switching SDT, the MAC entity of the UE may indicate a consistent LBT failure for SDT to upper layers (such as RRC layer) .

In another aspect, if a MAC PDU is transmitted and LBT failure indication is not received from lower layers and this MAC PDU includes the LBT failure indication or this MAC PDU is transmitted on the switched UL resource (and the switching is trigged by consistent LBT failure) , or if consistent LBT failure is triggered and not cancelled and a random access procedure is considered successfully completed, or a preamble or a MAC PDU in a random access procedure is transmitted, or if the configuration information for the consistent LBT failure for SDT (such as, lbt-FailureRecoveryConfig-SDT) is reconfigured by upper layers (such as, RRC layer) , the MAC entity of the UE may cancel the triggered consistent LBT failure.

Furthermore, if all triggered consistent LBT failures are cancelled in this serving cell or if the lbt-FailureDetectionTimer-SDT expires; or if lbt-FailureDetectionTimer-SDT or lbt-FailureInstanceMaxCount-SDT is reconfigured by upper layers, the MAC entity of the UE may set LBT_COUNTER_SDT to 0.

FIG. 3 illustrates an apparatus according to some embodiments of the present application. In some embodiments of the present application, the apparatus 300 may be the UE 101 as illustrated in FIG. 1 or other embodiments of the present application.

As shown in FIG. 3, the apparatus 300 may include a receiver 301, a transmitter 303, a processer 305, and a non-transitory computer-readable medium 307. The non-transitory computer-readable medium 307 has computer executable instructions stored therein. The processer 305 is configured to be coupled to the non-transitory computer readable medium 307, the receiver 301, and the transmitter 303. It is contemplated that the apparatus 300 may include more computer-readable mediums, receiver, transmitter and processors in some other embodiments of the present application according to practical requirements. In some embodiments of the present application, the receiver 301 and the transmitter 303 are integrated into a single device, such as a transceiver. In certain embodiments, the apparatus 300 may further include an input device, a memory, and/or other components.

In some embodiments of the present application, the non-transitory computer-readable medium 307 may have stored thereon computer-executable instructions to cause the apparatus 300 to implement the method according to embodiments of the present application.

FIG. 4 illustrates another apparatus according to some embodiments of the present application. In some embodiments of the present application, the apparatus 400 may be the BS 102 as illustrated in FIG. 1 or other embodiments of the present application.

As shown in FIG. 4, the apparatus 400 may include a receiver 401, a transmitter 403, a processer 405, and a non-transitory computer-readable medium 407. The non-transitory computer-readable medium 407 has computer executable instructions stored therein. The processer 405 is configured to be coupled to the non-transitory computer readable medium 407, the receiver 401, and the transmitter 403. It is contemplated that the apparatus 400 may include more computer-readable mediums, receiver, transmitter and processors in some other embodiments of the present application according to practical requirements. In some embodiments of the present application, the receiver 401 and the transmitter 403 are integrated into a single device, such as a transceiver. In certain embodiments, the apparatus 400 may further include an input device, a memory, and/or other components.

In some embodiments of the present application, the non-transitory computer-readable medium 407 may have stored thereon computer-executable instructions to cause the apparatus 400 to implement the method according to embodiments of the present application.

Persons skilled in the art should understand that as the technology develops and advances, the terminologies described in the present application may change, and should not affect or limit the principle and spirit of the present application.

Those having ordinary skill in the art would understand that the steps of a method described in connection with the aspects disclosed herein may be embodied directly in hardware, in a software module executed by a processor, or in a combination of the two. A software module may reside in RAM memory, flash memory, ROM memory, EPROM memory, EEPROM memory, registers, a hard disk, a removable disk, a CD-ROM, or any other form of storage medium known in the art. Additionally, in some aspects, the steps of a method may reside as one or any combination or set of codes and/or instructions on a non-transitory computer-readable medium, which may be incorporated into a computer program product.

While this disclosure has been described with specific embodiments thereof, it is evident that many alternatives, modifications, and variations may be apparent to those skilled in the art. For example, various components of the embodiments may be interchanged, added, or substituted in the other embodiments. Also, all of the elements of each figure are not necessary for operation of the disclosed embodiments. For example, one of ordinary skill in the art of the disclosed embodiments would be enabled to make and use the teachings of the disclosure by simply employing the elements of the independent claims. Accordingly, embodiments of the disclosure as set forth herein are intended to be illustrative, not limiting. Various changes may be made without departing from the spirit and scope of the disclosure.

In this document, the terms "comprises, " "comprising, " or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. An element proceeded by "a, " "an, " or the like does not, without more constraints, preclude the existence of additional identical elements in the process, method, article, or apparatus that comprises the element. Also, the term "another" is defined as at least a second or more. The terms "including, " "having, " and the like, as used herein, are defined as "comprising. "

Claims

A method, comprising:

receiving listen before talk (LBT) failure indications for small data transmission (SDT) ;

triggering consistent LBT failure for a first uplink (UL) resource for SDT in response to a number of the LBT failure indications exceeding or being equal to a predetermined threshold within a predetermined time duration for the first UL resource for SDT; and

performing a recovery procedure by switching the SDT from the first UL resource to a second UL resource in response to the consistent LBT failure for the first UL resource for SDT being triggered.
The method of Claim 1, wherein performing the recovery procedure further comprises: initiating a random access channel (RACH) procedure if there is no UL resource available for the SDT or any UL transmission.
The method of Claim 1, further comprising:

receiving configuration information for the consistent LBT failure for SDT by a system broadcast message or radio resource control (RRC) signaling,

wherein the configuration information indicates at least one of the predetermined threshold corresponding to a maximum number of the LBT failure indications received and the predetermined time duration corresponding to time duration for monitoring LBT failure for SDT.
The method of Claim 1, wherein the first UL resource is one of the following:

a UL pre-configured resource for SDT;

a physical uplink shared channel (PUSCH) resource and physical random access channel (PRACH) resource during a random access channel (RACH) procedure for SDT; and

any other UL resource for SDT.
The method of Claim 1, further comprising at least one of:

detecting the consistent LBT failure per UL pre-configured resource for SDT by counting the LBT failure indications for all UL transmissions;

detecting the consistent LBT failure per UL bandwidth part (BWP) for SDT by counting the LBT failure indications for all UL transmissions; and

detecting the consistent LBT failure per PRACH index, per MsgA PUSCH configuration, or Msg3 PUSCH configuration by counting the LBT failure indications for all UL transmissions.
The method of Claim 5, wherein each of the LBT failure indications comprises information indicating the LBT failure indication is for which UL pre-configured resource, which UL BWP, which PRACH index, which MsgA PUSCH configuration, or which Msg3 PUSCH configuration.
The method of Claim 5, wherein the consistent LBT failure is triggered for UL pre-configured resource for SDT, an UL BWP, PRACH index, MsgA PUSCH configuration, or Msg3 PUSCH configuration, when the counted number of the LBT failure indications exceeds or is equal to the predetermined threshold within the predetermined time duration for SDT.
The method of Claim 1, wherein switching the SDT from the first UL resource to the second UL resource comprises:

in the case of a plurality of UL resources for SDT being configured or available and information about which UL BWP the UL resources for SDT belong to being not configured, selecting the second UL resource for switching is in an order of priority for switching: each UL pre-configured resource for SDT which has not been indicated LBT failure, each MsgA resource including PRACH resource and MsgA PUSCH resource during a 2-step RACH procedure for SDT which has not been indicated LBT failure, each PRACH resource during a RACH procedure for SDT which has not been indicated LBT failure, and each PRACH resource during a RACH procedure not for SDT which has not been indicated LBT failure.
The method of Claim 1, wherein switching the SDT from the first UL resource to the second UL resource comprises:

in the case of a plurality of UL resources for SDT being configured or available and information about which UL BWP the UL resources for SDT belong to being configured, selecting the second UL resource for switching is in an order of priority for switching: each UL pre-configured resource for SDT on a same BWP as the first UL resource which has not been indicated LBT failure, each MsgA resource including PRACH resource and MsgA PUSCH resource during a 2-step RACH procedure for SDT on a same BWP as the first UL resource which has not been indicated LBT failure, each PRACH resource during a RACH procedure for SDT on a same BWP as the first UL resource which has not been indicated LBT failure, each UL pre-configured resource for SDT on another BWP which has not been indicated LBT failure, each MsgA resource including PRACH resource and MsgA PUSCH resource during a 2-step RACH procedure for SDT on another BWP which has not been indicated LBT failure, each PRACH resource during a RACH procedure for SDT on another BWP which has not been indicated LBT failure, each PRACH resource during a RACH procedure not for SDT on an BWP which has not been indicated LBT failure.
The method of Claim 9, further comprising: in the case that only a first UL pre-configured resource on a first UL BWP is configured and activated for SDT and the consistent LBT failure for the first UL pre-configured resource for SDT is triggered, autonomously switching the SDT from the first UL pre-configured resource to a second UL pre-configured resource on a second UL BWP which has not been indicated LBT failure.
The method of Claim 9, further comprising: in the case that a plurality of UL pre-configured resources on a first UL BWP are configured for SDT and at least one UL pre-configured resource of the plurality of UL pre-configured resources is activated and the consistent LBT failure for each of the plurality of UL pre-configured resources for SDT on the first BWP is triggered, autonomously switching the SDT to a second UL pre-configured resource on a second UL BWP with or without RA configuration which has not been indicated LBT failure.
The method of one of Claim 10 and Claim 11, further comprising: in the case that there is no the second UL pre-configured resource on the second UL BWP, autonomously switching the SDT to a third UL BWP with RA configuration which has not been indicated LBT failure.
The method of Claim 1, further comprising: initiating UL pre-configured resource based SDT or a RACH based SDT or a random access procedure.
The method of Claim 1, further comprising: indicating a consistent LBT failure for SDT to upper layers when there is no the second UL resource for switching.
The method of Claim 1, further comprising: canceling the triggered consistent LBT failure if a MAC PDU is transmitted and LBT failure indication is not received and this MAC PDU includes the LBT failure indication or this MAC PDU is transmitted on the second UL resource, or if consistent LBT failure is triggered and not cancelled and a random access procedure is considered successfully completed, or a preamble or a MAC PDU in a random access procedure is transmitted, or if configuration information for the consistent LBT failure for SDT is reconfigured by upper layers.