WO2025091275A1

WO2025091275A1 - Devices and methods of communication

Info

Publication number: WO2025091275A1
Application number: PCT/CN2023/128677
Authority: WO
Inventors: Da Wang; Lin Liang; Gang Wang
Original assignee: NEC Corp
Current assignee: NEC Corp
Priority date: 2023-10-31
Filing date: 2023-10-31
Publication date: 2025-05-08
Anticipated expiration: 2026-04-30

Abstract

Embodiments of the present disclosure relate to devices and methods of communication. In one aspect, upon determination that a terminal device is in a gap or is configured with a DRX configuration, the terminal device monitors a PDCCH if a condition comprising that a mobility procedure skipping a random access procedure is on-going is satisfied. In this way, PDCCH monitoring may be enhanced for a RACH-less mobility procedure and a latency of RACH-less mobility procedure may be shortened.

Description

DEVICES AND METHODS OF COMMUNICATION

TECHNICAL FIELD

Embodiments of the present disclosure generally relate to the field of telecommunication, and in particular, to devices and methods of communication for random access channel (RACH) -less mobility.

BACKGROUND

A RACH-less operation (i.e., skipping a random access (RA) procedure) may be supported in mobility procedures such as a layer 1 or layer 2 triggered mobility (LTM) cell switch, a handover and a primary secondary cell (PSCell) change. Skipping an RA procedure may bring benefits such as reduced mobility failure, reduced interruption time, and reduced signalling overhead. However, implementation of RACH-less mobility is still incomplete and needs to be further developed.

SUMMARY

In general, embodiments of the present disclosure provide methods, devices and computer storage media of communication for RACH-less mobility.

In a first aspect, there is provided a terminal device. The terminal device comprises a processor. The processor is configured to cause the terminal device to: determine that the terminal device is in a gap or is configured with a discontinuous reception (DRX) configuration; and in accordance with a determination that a condition is satisfied, monitor a physical downlink control channel (PDCCH) , the condition comprising that a mobility procedure skipping a random access procedure is on-going.

In a second aspect, there is provided a terminal device. The terminal device comprises a processor. The processor is configured to cause the terminal device to: determine that a mobility procedure skipping a random access procedure is on-going; and generate at least one of a medium access control (MAC) protocol data unit (PDU) or a cell-radio network temporary identifier (C-RNTI) MAC control element (CE) for an uplink grant for an initial uplink transmission to a target cell of the mobility procedure.

In a third aspect, there is provided a terminal device. The terminal device comprises a processor. The processor is configured to cause the terminal device to: determine that a timer of a configured grant for a mobility procedure skipping a random access procedure expires; and cancel using the configured grant for a transmission.

In a fourth aspect, there is provided a method of communication. The method comprises: determining, at a terminal device, that the terminal device is in a gap or is configured with a DRX configuration; and in accordance with a determination that a condition is satisfied, monitoring a PDCCH, the condition comprising that a mobility procedure skipping a random access procedure is on-going.

In a fifth aspect, there is provided a method of communication. The method comprises: determining, at a terminal device, that a mobility procedure skipping a random access procedure is on-going; and generating at least one of a MAC PDU or a C-RNTI MAC CE for an uplink grant for an initial uplink transmission to a target cell of the mobility procedure.

In a sixth aspect, there is provided a method of communication. The method comprises: determining, at a terminal device, that a timer of a configured grant for a mobility procedure skipping a random access procedure expires; and cancelling using the configured grant for a transmission.

In a seventh aspect, there is provided a computer readable medium having instructions stored thereon. The instructions, when executed on at least one processor, cause the at least one processor to perform the method according to any of the fourth to sixth aspects of the present disclosure.

Other features of the present disclosure will become easily comprehensible through the following description.

BRIEF DESCRIPTION OF THE DRAWINGS

Through the more detailed description of some embodiments of the present disclosure in the accompanying drawings, the above and other objects, features and advantages of the present disclosure will become more apparent, wherein:

FIG. 1 illustrates an example communication network in which some embodiments of the present disclosure can be implemented;

FIG. 2 illustrates a signaling chart illustrating an example process of communication according to embodiments of the present disclosure;

FIG. 3 illustrates a signaling chart illustrating another example process of communication according to embodiments of the present disclosure;

FIG. 4 illustrates a flowchart of an example method of communication implemented at a terminal device in accordance with some embodiments of the present disclosure;

FIG. 5 illustrates a flowchart of another example method of communication implemented at a terminal device in accordance with some embodiments of the present disclosure;

FIG. 6 illustrates a flowchart of another example method of communication implemented at a terminal device in accordance with some embodiments of the present disclosure; and

FIG. 7 is a simplified block diagram of a device that is suitable for implementing embodiments of the present disclosure.

Throughout the drawings, the same or similar reference numerals represent the same or similar element.

DETAILED DESCRIPTION

Principle of the present disclosure will now be described with reference to some embodiments. It is to be understood that these embodiments are described only for the purpose of illustration and help those skilled in the art to understand and implement the present disclosure, without suggesting any limitations as to the scope of the disclosure. The disclosure described herein can be implemented in various manners other than the ones described below.

In the following description and claims, unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skills in the art to which this disclosure belongs.

As used herein, the term ‘terminal device’ refers to any device having wireless or wired communication capabilities. Examples of the terminal device include, but not limited to, user equipment (UE) , personal computers, desktops, mobile phones, cellular phones, smart phones, personal digital assistants (PDAs) , portable computers, tablets, wearable devices, internet of things (IoT) devices, Ultra-reliable and Low Latency Communications (URLLC) devices, Internet of Everything (IoE) devices, machine type communication (MTC) devices, device on vehicle for V2X communication where X means pedestrian, vehicle, or infrastructure/network, devices for Integrated Access and Backhaul (IAB) , Space borne vehicles or Air borne vehicles in Non-terrestrial networks (NTN) including Satellites and High Altitude Platforms (HAPs) encompassing Unmanned Aircraft Systems (UAS) , eXtended Reality (XR) devices including different types of realities such as Augmented Reality (AR) , Mixed Reality (MR) and Virtual Reality (VR) , the unmanned aerial vehicle (UAV) commonly known as a drone which is an aircraft without any human pilot, devices on high speed train (HST) , or image capture devices such as digital cameras, sensors, gaming devices, music storage and playback appliances, or Internet appliances enabling wireless or wired Internet access and browsing and the like. The ‘terminal device’ can further has ‘multicast/broadcast’ feature, to support public safety and mission critical, V2X applications, transparent IPv4/IPv6 multicast delivery, IPTV, smart TV, radio services, software delivery over wireless, group communications and IoT applications. It may also incorporate one or multiple Subscriber Identity Module (SIM) as known as Multi-SIM. The term “terminal device” can be used interchangeably with a UE, a mobile station, a subscriber station, a mobile terminal, a user terminal or a wireless device.

The term “network device” refers to a device which is capable of providing or hosting a cell or coverage where terminal devices can communicate. Examples of a network device include, but not limited to, a Node B (NodeB or NB) , an evolved NodeB (eNodeB or eNB) , a next generation NodeB (gNB) , a transmission reception point (TRP) , a remote radio unit (RRU) , a radio head (RH) , a remote radio head (RRH) , an IAB node, a low power node such as a femto node, a pico node, a reconfigurable intelligent surface (RIS) , and the like.

The terminal device or the network device may have Artificial intelligence (AI) or Machine learning capability. It generally includes a model which has been trained from numerous collected data for a specific function, and can be used to predict some information.

The terminal or the network device may work on several frequency ranges, e.g. FR1 (410 MHz to 7125 MHz) , FR2 (24.25GHz to 71GHz) , frequency band larger than 100GHz as well as Tera Hertz (THz) . It can further work on licensed/unlicensed/shared spectrum. The terminal device may have more than one connections with the network devices under Multi-Radio Dual Connectivity (MR-DC) application scenario. The terminal device or the network device can work on full duplex, flexible duplex and cross division duplex modes.

The embodiments of the present disclosure may be performed in test equipment, e.g. signal generator, signal analyzer, spectrum analyzer, network analyzer, test terminal device, test network device, channel emulator.

In one embodiment, the terminal device may be connected with a first network device and a second network device. One of the first network device and the second network device may be a master node and the other one may be a secondary node. The first network device and the second network device may use different radio access technologies (RATs) . In one embodiment, the first network device may be a first RAT device and the second network device may be a second RAT device. In one embodiment, the first RAT device is eNB and the second RAT device is gNB. Information related with different RATs may be transmitted to the terminal device from at least one of the first network device or the second network device. In one embodiment, first information may be transmitted to the terminal device from the first network device and second information may be transmitted to the terminal device from the second network device directly or via the first network device. In one embodiment, information related with configuration for the terminal device configured by the second network device may be transmitted from the second network device via the first network device. Information related with reconfiguration for the terminal device configured by the second network device may be transmitted to the terminal device from the second network device directly or via the first network device.

As used herein, the singular forms ‘a’ , ‘an’a nd ‘the’a re intended to include the plural forms as well, unless the context clearly indicates otherwise. The term ‘includes’ and its variants are to be read as open terms that mean ‘includes, but is not limited to. ’ The term ‘based on’ is to be read as ‘at least in part based on. ’ The term ‘one embodiment’a nd ‘an embodiment’a re to be read as ‘at least one embodiment. ’ The term ‘another embodiment’ is to be read as ‘at least one other embodiment. ’ The terms ‘first, ’ ‘second, ’a nd the like may refer to different or same objects. Other definitions, explicit and implicit, may be included below.

In some examples, values, procedures, or apparatus are referred to as ‘best, ’ ‘lowest, ’ ‘highest, ’ ‘minimum, ’ ‘maximum, ’ or the like. It will be appreciated that such descriptions are intended to indicate that a selection among many used functional alternatives can be made, and such selections need not be better, smaller, higher, or otherwise preferable to other selections.

In the context of the present disclosure, the term “acell switch” may be interchangeably used with “reconfiguration with sync for secondary cell group (SCG) or master cell group (MCG) ” or “acell change” . The term “PSCell” refers to a SpCell of a SCG, the term “PCell” refers to a SpCell of a MCG, and the term “SpCell” refers to a primary cell of a SCG or MCG. The term “SCell” refers to a secondary cell. The term “radio resource control (RRC) reconfiguration” may be interchangeably used with “RRC reconfiguration message” . The term “initial uplink (UL) transmission” may be interchangeably used with “first physical uplink shared channel (PUSCH) transmission” .

As mentioned above, implementation of RACH-less mobility is still incomplete. Embodiments of the present disclosure provide solutions of communication for RACH-less mobility.

In one aspect, upon determination that a terminal device is in a gap or is configured with a DRX configuration, the terminal device monitors a PDCCH if a condition comprising that a mobility procedure skipping a random access procedure is on-going is satisfied. In this way, PDCCH monitoring may be enhanced for a RACH-less mobility procedure and a latency of RACH-less mobility procedure may be shortened.

In another aspect, upon determination that a mobility procedure skipping a random access procedure is on-going, a terminal device generates at least one of a MAC PDU or a C-RNTI MAC CE for an uplink grant for an initial uplink transmission to a target cell of the mobility procedure. In this way, an initial UL transmission may be performed for a RACH-less mobility procedure.

In still another aspect, upon determination that a timer of a configured grant for a mobility procedure skipping a random access procedure expires, a terminal device cancels using the configured grant for a transmission. In this way, handling of a configured grant for a RACH-less mobility procedure after expiry of a timer of the configuration grant is defined.

Principles and implementations of the present disclosure will be described in detail below with reference to the figures.

EXAMPLE OF COMMUNICATION NETWORK

FIG. 1 illustrates a schematic diagram of an example communication network 100 in which some embodiments of the present disclosure can be implemented. As shown in FIG. 1, the communication network 100 may include a terminal device 110 and a network device 120. The network device 120 provides a plurality of cells (cells 121, 122, 123 and 124 as shown) to serve one or more terminal devices.

It is to be understood that the number of devices or cells in FIG. 1 is given for the purpose of illustration without suggesting any limitations to the present disclosure. The communication network 100 may include any suitable number of network devices and/or terminal devices and/or cells adapted for implementing implementations of the present disclosure.

As shown in FIG. 1, the terminal device 110 may communicate with the network device 120 via a channel such as a wireless communication channel. The communications in the communication network 100 may conform to any suitable standards including, but not limited to, Global System for Mobile Communications (GSM) , Long Term Evolution (LTE) , LTE-Evolution, LTE-Advanced (LTE-A) , New Radio (NR) , Wideband Code Division Multiple Access (WCDMA) , Code Division Multiple Access (CDMA) , GSM EDGE Radio Access Network (GERAN) , Machine Type Communication (MTC) and the like. The embodiments of the present disclosure may be performed according to any generation communication protocols either currently known or to be developed in the future. Examples of the communication protocols include, but not limited to, the first generation (1G) , the second generation (2G) , 2.5G, 2.75G, the third generation (3G) , the fourth generation (4G) , 4.5G, the fifth generation (5G) communication protocols, 5.5G, 5G-Advanced networks, or the sixth generation (6G) networks.

Communication in a direction from the terminal device 110 towards the network device 120 is referred to as uplink (UL) communication, while communication in a reverse direction from the network device 120 towards the terminal device 110 is referred to as downlink (DL) communication. The terminal device 110 can move amongst the cells of the network device 120 and possibly other network devices. In UL communication, the terminal device 110 may transmit UL data and control information to the network device 120 via a UL channel. In DL communication, the network device 120 may transmit DL data and control information to the terminal device 110 via a DL channel.

In some embodiments, the terminal device 110 may be located within coverage of cell 121 of the network device 120, and the terminal device 110 may communicate with the network device 120 based on network configuration. In this case, the cell 121 may be referred to as a serving cell of the terminal device 110. Any of the cells 122, 123 and 124 may be referred to as a candidate cell of the terminal device 110.

In some embodiments, the terminal device 110 may establish a dual connection (i.e., simultaneous connection) with the network device 120 and another network device (not shown) . In some embodiments, the network device 120 may serve as a master node (MN) . In these embodiments, the terminal device 110 may communicate with the network device 120 via a set of serving cells. The set of serving cells form a MCG, and a primary cell in the MCG is called as PCell. In some scenarios, the PCell may be changed from the cell 121 to a candidate cell (also called as a target cell, e.g., the cell 122) . Such PCell change is called as a handover (HO) procedure.

In some embodiments, the network device 120 may serve as a secondary node (SN) . In these embodiments, the set of serving cells provided by the network device 120 form a SCG, and a primary cell in the SCG is called as PSCell. In some scenarios, the PSCell may be changed from the cell 121 to a candidate cell (also called as a target cell, e.g., the cell 122) . This procedure is called as a PSCell change procedure.

In some embodiments, the network device 120 may receive L1 measurement reports from the terminal device 110. Based on the L1 measurement reports, the network device 120 may change a serving cell (e.g., PCell or PSCell) of the terminal device 110 through a MAC CE. This procedure is called as an LTM procedure or an LTM cell switch procedure.

In the context of the present disclosure, the term “amobility procedure” may refer to a handover procedure, a PSCell change procedure, an LTM procedure, and any other cell change or switch procedures existing or to be developed.

For a RACH-less mobility procedure, a terminal device may access a target cell via a configured grant (CG) provided in a command for cell switch or change. The terminal device may also monitor a PDCCH for dynamic scheduling from the target cell upon the cell switch or change for an initial UL (e.g., PUSCH) transmission.

Embodiments of the present disclosure provide solutions of communication to enhance the RACH-less mobility procedure. These solutions will be described with reference to FIGs. 2 to 4 below.

EXAMPLE IMPLEMENTATION OF PDCCH MONITORING

Currently, if an RA procedure is skipped for a mobility procedure and a configured grant is not pre-configured for initial UL transmission, a terminal device needs to perform a PDCCH monitoring on a target cell for dynamic grant for the initial UL transmission upon performance of the mobility procedure.

However, in some scenarios, if the terminal device is configured with a DRX configuration, the terminal device may monitor the PDCCH discontinuously based on the DRX configuration. For example, the terminal device is unable to monitor the PDCCH if the terminal device is not in an active time. In some scenarios, if the terminal device is configured with a gap (e.g., a measurement gap or a multi-universal subscriber identity module (MUSIM) gap or a positioning reference signal (PRS) processing window (PPW) ) , the terminal device may monitor the PDCCH discontinuously based on the gap configuration. For example, the terminal device is unable to monitor the PDCCH if the terminal device is in the gap (in other words, during the gap) . In these scenarios, latency increment for the mobility procedure may be caused.

In view of this, embodiments of the present disclosure provide a solution of communication for PDCCH monitoring in RACH-less mobility. The solution will be described in connection with FIG. 2 below.

FIG. 2 illustrates a signaling chart illustrating an example process 200 of communication according to embodiments of the present disclosure. For the purpose of discussion, the process 200 will be described with reference to FIG. 1. The process 200 may involve the terminal device 110 and the network device 120 as illustrated in FIG. 1. In this example, the network device 120 provides a serving cell (e.g., the cell 121) for the terminal device 110 and also provides one or more candidate cells or target cells of the mobility procedure for the terminal device 110. The serving cell may be SpCell, PCell or PSCell of the terminal device 110.

As shown in FIG. 2, the terminal device 110 may determine 210 that the terminal device 110 is in a gap or is configured with a DRX configuration. In some embodiments, the DRX configuration may indicate an active time for serving cells in a DRX group. It is to be understood that the DRX configuration may comprise any other suitable DRX information, and the present disclosure does not limit this aspect.

In some embodiments, the gap may comprise a measurement gap during which the terminal device 110 is configured to perform measurements. In some embodiments, the gap may comprise a MUSIM gap during which the terminal device 110 is configured to perform a service on another USIM. In some embodiments, the gap may comprise a PRS processing window during which the terminal device 110 is configured to perform a PRS processing. It is to be understood that any other suitable time gaps existing or to be developed in future may also be feasible.

Continuing to refer to FIG. 2, the terminal device 110 may determine 220 whether a condition is satisfied. In some embodiments, the terminal device 110 may determine whether a mobility procedure skipping an RA procedure is on-going. In some embodiments, the terminal device 110 may determine whether a mobility procedure skipping an RA procedure is on-going and a PDCCH indicating a transmission addressed to a C-RNTI of a MAC entity of the terminal device 110 has not been received from a serving cell. For example, the transmission may be a new transmission. In some embodiments, the terminal device 110 may determine whether a mobility procedure skipping an RA procedure is on-going and a configured grant for an initial UL transmission is unavailable (e.g., not configured for a target cell of the mobility procedure) . It is to be understood that any combination of the above conditions may also be feasible.

Continuing to refer to FIG. 2, if the condition is satisfied, the terminal device 110 may monitor 230 the PDCCH.

In some embodiments, the terminal device 110 may be configured with the DRX configuration. In these embodiments, if the condition is satisfied, the terminal device 110 may determine that the terminal device 110 is in an active time for a DRX group, and the terminal device 110 may monitor the PDCCH in the active time. In other words, the active time for the serving cells (including the target cell of the mobility procedure) in a DRX group may include the time when the condition is satisfied. The terminal device 110 may monitor the PDCCH on the serving cells in active time of the DRX group.

For illustration, an example procedure may be described as below.

When DRX is configured, the Active Time for Serving Cells in a DRX group includes the time while:

- there is an ongoing RACH-less LTM cell switch or RACH-less handover (reconfiguration with sync for MCG) ; or

- there is an ongoing RACH-less LTM cell switch or RACH-less handover (reconfiguration with sync for MCG) , and an PDCCH indicating a new transmission addressed to the C-RNTI of the MAC entity has not been received; or

- there is an ongoing RACH-less LTM cell switch or RACH-less handover (reconfiguration with sync for MCG) , and configured grant for initial UL transmission is not available.

In some embodiments where the terminal device 110 is configured with the DRX configuration, if the condition is satisfied, the terminal device 110 may monitor the PDCCH regardless of the DRX configuration. For example, the terminal device 110 may monitor the PDCCH addressed to C-RNTI or a configured scheduling radio network temporary identifier (CS-RNTI) .

For illustration, an example procedure may be described as below.

When in RRC_CONNECTED, if DRX is configured, and RACH-less LTM cell switch or handover is not on-going, for all the activated Serving Cells, the MAC entity may monitor the PDCCH discontinuously using the DRX operation; otherwise the MAC entity shall monitor the PDCCH.

For illustration, another example procedure may be described as below.

When in RRC_CONNECTED, if DRX is configured, and RACH-less LTM cell switch or handover is not on-going, or RACH-less LTM cell switch or handover is on-going and an PDCCH indicating a new transmission addressed to the C-RNTI entity has been received, for all the activated Serving Cells, the MAC entity may monitor the PDCCH discontinuously using the DRX operation; otherwise the MAC entity shall monitor the PDCCH.

For illustration, still another example procedure may be described as below.

When in RRC_CONNECTED, if DRX is configured, and RACH-less LTM cell switch or handover is not on-going, or RACH-less LTM cell switch or handover is on-going and configured grant for initial UL transmission is available, for all the activated Serving Cells, the MAC entity may monitor the PDCCH discontinuously using the DRX operation; otherwise the MAC entity shall monitor the PDCCH.

In some embodiments, the terminal device 110 may be configured with the gap. In these embodiments, if the condition is satisfied, the terminal device 110 may monitor the PDCCH regardless of an occurrence of the gap. For example, the terminal device 110 may monitor the PDCCH addressed to C-RNTI or a CS-RNTI.

In some embodiments, the gap is a measurement gap. During an activated measurement gap, the terminal device 110 may monitor the PDCCH (e.g., addressed to C-RNTI and CS-RNTI) if the condition is satisfied.

For illustration, an example procedure of handling of a measurement gap may be described as below.

During an activated measurement gap, the MAC entity shall, on the Serving Cell (s) in the corresponding frequency range of the measurement gap configured by measGapConfig:

1> not perform the transmission of HARQ feedback, SR, and CSI;

1> not report SRS;

1> not transmit on UL-SCH except for Msg3 or the MSGA payload;

1> if the ra-ResponseWindow or the ra-ContentionResolutionTimer or the msgB-ResponseWindow is running; or

2> monitor the PDCCH.

1> else if there is an ongoing RACH-less LTM cell switch or handover, or

1> else if there is an ongoing RACH-less LTM cell switch or handover, and an PDCCH indicating a new transmission addressed to the C-RNTI of the MAC entity has not been received, or

1> else if there is an ongoing RACH-less mobility procedure, and configured grant for initial UL transmission is not available,

2> monitor the PDCCH;

1> else:

2> not monitor the PDCCH;

2> not receive on DL-SCH.

In this example, an information element (IE) “measGapConfig” denotes a measurement gap configuration, an IE “ra-ResponseWindow” denotes a random access response window, an IE “ra-ContentionResolutionTimer” denotes a random access contention resolution timer, and an IE “msgB-ResponseWindow” denotes a msgB response window.

In some embodiments, the gap is a PRS processing window. When the PRS processing window is activated and a PRS has a priority higher than a DL transmission (e.g., DL channel and signals) , the terminal device 110 may monitor the PDCCH (e.g., addressed to C-RNTI and CS-RNTI) if the condition is satisfied.

For illustration, an example procedure of handling of a PRS processing window may be described as below.

When PPW is activated and PRS has higher priority than DL channel and signals, for the affected symbols within the PPW, the MAC entity shall:

1> if the ra-ResponseWindow or the ra-ContentionResolutionTimer or the msgB-ResponseWindow is running: or

2> monitor the PDCCH.

1> else if there is an ongoing RACH-less LTM cell switch or handover, or

2> monitor the PDCCH;

1> else:

2> not receive DL-SCH;

2> not receive PDCCH.

With the process 200, PDCCH monitoring may be enhanced for a RACH-less mobility procedure and a latency of RACH-less mobility procedure may be shortened.

EXAMPLE IMPLEMENTATION OF INITIAL UL TRANSMISSION

For a mobility procedure such as an LTM cell switch, if an RA procedure is skipped, an initial UL transmission is required by a terminal device to indicate arrival to a target cell (e.g., a target SCG cell) of the mobility procedure. If signaling radio bearer (SRB3) is not configured, a RRCReconfigurationComplete message should be sent to MN/MCG using signaling radio bearer 1 (SRB1) . If the terminal device has no data to be transmitted, no MAC PDU would be generated if the terminal device is configured to skip an UL transmission. Thus, how to perform an initial UL transmission is unclear.

In view of this, embodiments of the present disclosure provide a solution of communication for an initial UL transmission in RACH-less mobility. The solution will be described below in connection with FIG. 3.

FIG. 3 illustrates a signaling chart illustrating another example process 300 of communication according to embodiments of the present disclosure. For the purpose of discussion, the process 300 will be described with reference to FIG. 1. The process 300 may involve the terminal device 110 and the network device 120 as illustrated in FIG. 1. In this example, the network device 120 provides a serving cell (e.g., the cell 121) for the terminal device 110 and also provides one or more candidate cells or target cells of the mobility procedure for the terminal device 110. The serving cell may be SpCell, PCell or PSCell of the terminal device 110.

As shown in FIG. 3, the terminal device 110 may determine 310 that a mobility procedure skipping an RA procedure is on-going. In this case, the terminal device 110 may generate and transmit 320 at least one of a MAC PDU or a C-RNTI MAC CE for an UL grant for an initial UL transmission to a target cell of the mobility procedure.

In some embodiments, when there is an on-going mobility procedure, the terminal device 110 may always generate the MAC PDU for the UL grant for the initial UL transmission to the target cell, even if the terminal device 110 is configured to skip an UL transmission.

In some embodiments, even if the terminal device 110 is configured with skip uplink transmission configuration (e.g., enhancedSkipUplinkTxDynamic, enhancedSkipUplinkTxConfigured, or skipUplinkTxDynamic) , and there is no uplink control information (UCI) to be multiplexed on this physical uplink shared channel (PUSCH) transmission) , there is no aperiodic channel status information (CSI) requested for this PUSCH transmission, the MAC PDU includes zero MAC SDUs, and the MAC PDU includes only a periodic buffer status report (BSR) and there is no data available for any logical channel group (LCG) , or the MAC PDU includes only a padding BSR, the terminal device 110 may still generate a MAC PDU if the UL grant is for initial UL transmission (i.e., first PUSCH transmission) of a RACH-less mobility procedure such as a RACH-less LTM cell switch procedure.

In some embodiments, if the terminal device 110 is configured with skip uplink transmission configuration, and if there is no UCI to be multiplexed on this PUSCH transmission, there is no aperiodic CSI requested for this PUSCH transmission, the MAC PDU includes zero MAC SDUs, and the MAC PDU includes only the periodic BSR and there is no data available for any LCG, or the MAC PDU includes only the padding BSR, the UE may not generate a MAC PDU only if the UL grant is not for an initial UL transmission (i.e., first PUSCH transmission) of a RACH-less LTM cell switch procedure.

For illustration, an example procedure may be described as below.

1> if the grant is not for first PUSCH transmission of RACH-less LTM cell switch, and if the MAC entity is configured with enhancedSkipUplinkTxDynamic with value true and the grant indicated to the HARQ entity was addressed to a C-RNTI, or if the MAC entity is configured

with enhancedSkipUplinkTxConfigured with value true and the grant indicated to the HARQ entity is a configured uplink grant:

2> if there is no UCI to be multiplexed on this PUSCH transmission;

and

2> if there is no aperiodic CSI requested for this PUSCH transmission;

and

2> if the MAC PDU includes zero MAC SDUs; and

2> if the MAC PDU includes only the periodic BSR and there is no data available for any LCG, or the MAC PDU includes only the padding BSR:

3> not generate a MAC PDU for the HARQ entity.

1> else if the grant is not for first PUSCH transmission of RACH-less LTM cell switch, and if the MAC entity is configured with skipUplinkTxDynamic with value true and the grant indicated to the HARQ entity was addressed to a C-RNTI, or the grant indicated to the HARQ entity is a configured uplink grant:

2> if there is no aperiodic CSI requested for this PUSCH transmission;

and

2> if the MAC PDU includes zero MAC SDUs; and

3> not generate a MAC PDU for the HARQ entity.

In this example, an IE “enhancedSkipUplinkTxDynamic” and “skipUplinkTxDynamic” denote configurations of skipping a dynamic uplink transmission, an IE “enhancedSkipUplinkTxConfigured” denotes a configuration of skipping a configured uplink transmission.

In some embodiments, when there is an on-going mobility procedure, the terminal device 110 may generate the C-RNTI MAC CE for the UL grant for the initial UL transmission to the target cell.

In some embodiments, if the UL grant is for the initial UL transmission to the target cell, the terminal device 110 may indicate a multiplexing and assembly entity of the terminal device 110 to include the C-RNTI MAC CE in a subsequent UL transmission. For example, upon allocation of resources, if the UL grant is for first PUSCH transmission of a RACH-less LTM cell switch procedure, the terminal device 110 may indicate to the multiplexing and assembly entity to include a C-RNTI MAC CE in the subsequent UL transmission.

In some embodiments, if the UL grant is for the initial UL transmission to the target cell and no UL data is to be transmitted, the terminal device 110 may indicate the multiplexing and assembly entity of the terminal device 110 to include the C-RNTI MAC CE in the subsequent UL transmission. For example, upon allocation of resources, if the UL grant is for first PUSCH transmission of a RACH-less LTM cell switch procedure, and there is no UL data to be transmitted (e.g., the MAC PDU includes zero MAC SDUs, there is no UCI to be multiplexed on this PUSCH transmission, there is no aperiodic CSI requested for this PUSCH transmission, and the MAC PDU includes only the periodic BSR and there is no data available for any LCG, or the MAC PDU includes only the padding BSR) , the terminal device 110 may indicate to the multiplexing and assembly entity to include a C-RNTI MAC CE in the subsequent UL transmission.

In some embodiments, if the UL grant is for the initial UL transmission to the target cell, no UL data is to be transmitted and the terminal device 110 is configured to skip a UL transmission, the terminal device 110 may indicate the multiplexing and assembly entity of the terminal device 110 to include the C-RNTI MAC CE in the subsequent UL transmission. For example, upon allocation of resources, if the terminal device 110 is configured to skip the UL TX transmission, and there is no UL data to be transmitted (e.g., the MAC PDU includes zero MAC SDUs, there is no UCI to be multiplexed on this PUSCH transmission, there is no aperiodic CSI requested for this PUSCH transmission, and the MAC PDU includes only the periodic BSR and there is no data available for any LCG, or the MAC PDU includes only the padding BSR) , if the UL grant is for first PUSCH transmission of a RACH-less LTM cell switch procedure, the terminal device 110 may indicate to the multiplexing and assembly entity to include a C-RNTI MAC CE in the subsequent UL transmission; else, the terminal device 110 may not generate a MAC PDU for the HARQ entity.

With the process 300, an initial UL transmission may be performed for a RACH-less mobility procedure.

EXAMPLE IMPLEMENTATION OF CG HANDLING

Currently, if a timer (e.g., configuredGrantTimer) of a configured grant for a RACH-less mobility expires, a terminal device does not consider a RACH-less mobility failure. Thus, how to handle the next CG resource after expiry of the timer is unclear.

In view of this, embodiments of the present disclosure provide a solution of communication for CG handling. In the solution, upon determination that a timer (e.g., configuredGrantTimer) of a CG for a mobility procedure skipping an RA procedure expires, the terminal device 110 may cancel using (i.e., not use) the CG for a transmission. In some embodiments, upon expiry of the timer, the terminal device 110 may not use the CG for a new transmission or retransmission.

In some embodiments, upon expiry of the timer, the terminal device 110 may clear the CG. In some embodiments, upon expiry of the timer, the terminal device 110 may suspend the CG. In some embodiments, upon expiry of the timer, the terminal device 110 may consider the CG as invalid. In some embodiments, upon expiry of the timer, the terminal device 110 may skip or ignore the CG. In some embodiments, upon expiry of the timer, the terminal device 110 may not deliver the CG and hybrid automatic repeat request (HARQ) information associated with the CG to a HARQ entity of the terminal device 110. In other words, during running of the timer, the terminal device 110 may deliver the CG and HARQ information associated with the CG to a HARQ entity of the terminal device 110.

In this way, handling of CG for RACH-less mobility after expiry of a CG timer may be defined.

EXAMPLE IMPLEMENTATION OF METHODS

Accordingly, embodiments of the present disclosure provide methods of communication implemented at a terminal device. These methods will be described below with reference to FIGs. 4 to 6.

FIG. 4 illustrates a flowchart of an example method 400 of communication implemented at a terminal device in accordance with some embodiments of the present disclosure. For example, the method 400 may be performed at the terminal device 110 as shown in FIG. 1. For the purpose of discussion, in the following, the method 400 will be described with reference to FIG. 1. It is to be understood that the method 400 may include additional blocks not shown and/or may omit some blocks as shown, and the scope of the present disclosure is not limited in this regard.

At block 410, the terminal device 110 determines that the terminal device 110 is in a gap or is configured with a DRX configuration. In some embodiments, the gap may comprise at least one of the following: a measurement gap, a MUSIM gap, or a PRS processing window.

At block 420, the terminal device 120 determines a condition is satisfied. The condition comprises that a mobility procedure skipping an RA procedure is on-going. In some embodiments, the condition may further comprise that a PDCCH indicating a transmission addressed to a C-RNTI of a MAC entity of the terminal device 110 has not been received from a serving cell. In some embodiments, the condition may further comprise that a CG for an initial UL transmission is unavailable.

In some embodiments, the mobility procedure may comprise an LTM procedure. In some embodiments, the mobility procedure may comprise a handover procedure. In some embodiments, the mobility procedure may comprise a PSCell change procedure.

At block 430, the terminal device 120 monitors a PDCCH.

In some embodiments where the terminal device 110 is configured with the DRX configuration, if the condition is satisfied, the terminal device 110 may determine that the terminal device 110 is in an active time for a DRX group, and monitor the PDCCH in the active time.

In some embodiments where the terminal device 110 is configured with the DRX configuration, the terminal device 110 may monitor the PDCCH regardless of the DRX configuration.

In some embodiments where the terminal device 110 is in the gap, the terminal device 110 may monitor the PDCCH regardless of an occurrence of the gap. In some embodiments where the gap is a measurement gap, the terminal device 110 may determine that the condition is satisfied during an activated measurement gap. In some embodiments where the gap is a PRS processing window, the terminal device 110 may determine that the condition is satisfied upon the PRS processing window is activated and a PRS has a priority higher than a DL transmission.

With the method 400, PDCCH monitoring may be carried out for a RACH-less mobility procedure and a latency of RACH-less mobility procedure may be shortened.

FIG. 5 illustrates a flowchart of another example method 500 of communication implemented at a terminal device in accordance with some embodiments of the present disclosure. For example, the method 500 may be performed at the terminal device 110 as shown in FIG. 1. For the purpose of discussion, in the following, the method 500 will be described with reference to FIG. 1. It is to be understood that the method 500 may include additional blocks not shown and/or may omit some blocks as shown, and the scope of the present disclosure is not limited in this regard.

At block 510, the terminal device 110 determines that a mobility procedure skipping an RA procedure is on-going. In some embodiments, the mobility procedure may comprise an LTM procedure. In some embodiments, the mobility procedure may comprise a handover procedure. In some embodiments, the mobility procedure may comprise a PSCell change procedure.

At block 520, the terminal device 110 generates at least one of a MAC PDU or a C-RNTI MAC CE for a UL grant for an initial UL transmission to a target cell of the mobility procedure.

In some embodiments for the MAC PDU, if the terminal device 110 is configured to skip an UL transmission, the terminal device 110 may generate the MAC PDU. In other words, the terminal device 110 may generate the MAC PDU even if the terminal device 110 is configured to skip an UL transmission.

In some embodiments for the C-RNTI MAC CE, if the UL grant is for the initial UL transmission to the target cell, the terminal device 110 may indicate a multiplexing and assembly entity of the terminal device 110 to include the C-RNTI MAC CE in a subsequent UL transmission.

In some embodiments for the C-RNTI MAC CE, if the UL grant is for the initial UL transmission to the target cell and no UL data is to be transmitted, the terminal device 110 may indicate the multiplexing and assembly entity of the terminal device 110 to include the C-RNTI MAC CE in the subsequent UL transmission.

In some embodiments for the C-RNTI MAC CE, if the UL grant is for the initial UL transmission to the target cell, no UL data is to be transmitted and the terminal device 110 is configured to skip an UL transmission, the terminal device 110 may indicate the multiplexing and assembly entity of the terminal device 110 to include the C-RNTI MAC CE in the subsequent UL transmission.

With the method 500, an initial UL transmission may be performed for a RACH-less mobility procedure.

FIG. 6 illustrates a flowchart of another example method 600 of communication implemented at a terminal device in accordance with some embodiments of the present disclosure. For example, the method 600 may be performed at the terminal device 110 as shown in FIG. 1. For the purpose of discussion, in the following, the method 600 will be described with reference to FIG. 1. It is to be understood that the method 600 may include additional blocks not shown and/or may omit some blocks as shown, and the scope of the present disclosure is not limited in this regard.

At block 610, the terminal device 110 determines that a timer of a CG for a mobility procedure skipping an RA procedure expires. In some embodiments, the mobility procedure may comprise an LTM procedure. In some embodiments, the mobility procedure may comprise a handover procedure. In some embodiments, the mobility procedure may comprise a PSCell change procedure.

At block 620, the terminal device 110 cancels using the CG for a transmission.

In some embodiments, the terminal device 110 may clear the CG. In some embodiments, the terminal device 110 may suspend the CG. In some embodiments, the terminal device 110 may consider the CG as invalid. In some embodiments, the terminal device 110 may skip or ignore the CG. In some embodiments, the terminal device 110 may not deliver the CG and HARQ information associated with the CG to a HARQ entity of the terminal device 110.

With the method 600, handling of a configured grant for a RACH-less mobility procedure after expiry of a timer of the configuration grant is defined.

It is to be understood that the operations of methods 400 to 600 correspond to that in the solutions described above, and thus other details are not repeated here for conciseness.

EXAMPLE IMPLEMENTATION OF DEVICES

FIG. 7 is a simplified block diagram of a device 700 that is suitable for implementing embodiments of the present disclosure. The device 700 can be considered as a further example implementation of the terminal device 110 or the network device 120 as shown in FIG. 1. Accordingly, the device 700 can be implemented at or as at least a part of the terminal device 110 or the network device 120.

As shown, the device 700 includes a processor 710, a memory 720 coupled to the processor 710, a suitable transceiver 740 coupled to the processor 710, and a communication interface coupled to the transceiver 740. The memory 710 stores at least a part of a program 730. The transceiver 740 may be for bidirectional communications or a unidirectional communication based on requirements. The transceiver 740 may include at least one of a transmitter 742 or a receiver 744. The transmitter 742 and the receiver 744 may be functional modules or physical entities. The transceiver 740 has at least one antenna to facilitate communication, though in practice an Access Node mentioned in this application may have several ones. The communication interface may represent any interface that is necessary for communication with other network elements, such as X2/Xn interface for bidirectional communications between eNBs/gNBs, S1/NG interface for communication between a Mobility Management Entity (MME) /Access and Mobility Management Function (AMF) /SGW/UPF and the eNB/gNB, Un interface for communication between the eNB/gNB and a relay node (RN) , or Uu interface for communication between the eNB/gNB and a terminal device.

The program 730 is assumed to include program instructions that, when executed by the associated processor 710, enable the device 700 to operate in accordance with the embodiments of the present disclosure, as discussed herein with reference to FIGs. 1 to 6. The embodiments herein may be implemented by computer software executable by the processor 710 of the device 700, or by hardware, or by a combination of software and hardware. The processor 710 may be configured to implement various embodiments of the present disclosure. Furthermore, a combination of the processor 710 and memory 720 may form processing means 750 adapted to implement various embodiments of the present disclosure.

The memory 720 may be of any type suitable to the local technical network and may be implemented using any suitable data storage technology, such as a non-transitory computer readable storage medium, semiconductor based memory devices, magnetic memory devices and systems, optical memory devices and systems, fixed memory and removable memory, as non-limiting examples. While only one memory 720 is shown in the device 700, there may be several physically distinct memory modules in the device 700. The processor 710 may be of any type suitable to the local technical network, and may include one or more of general purpose computers, special purpose computers, microprocessors, digital signal processors (DSPs) and processors based on multicore processor architecture, as non-limiting examples. The device 700 may have multiple processors, such as an application specific integrated circuit chip that is slaved in time to a clock which synchronizes the main processor.

In some embodiments, a terminal device comprises a circuitry configured to: determine that the terminal device is in a gap or is configured with a DRX configuration; and in accordance with a determination that a condition is satisfied, monitor a PDCCH, the condition comprising that a mobility procedure skipping a random access procedure is on-going.

In some embodiments, a terminal device comprises a circuitry configured to: determine that a mobility procedure skipping a random access procedure is on-going; and generate at least one of a MAC PDU or a C-RNTI MAC CE for an uplink grant for an initial uplink transmission to a target cell of the mobility procedure.

In some embodiments, a terminal device comprises a circuitry configured to: determine that a timer of a configured grant for a mobility procedure skipping a random access procedure expires; and cancel using the configured grant for a transmission.

The term “circuitry” used herein may refer to hardware circuits and/or combinations of hardware circuits and software. For example, the circuitry may be a combination of analog and/or digital hardware circuits with software/firmware. As a further example, the circuitry may be any portions of hardware processors with software including digital signal processor (s) , software, and memory (ies) that work together to cause an apparatus, such as a terminal device or a network device, to perform various functions. In a still further example, the circuitry may be hardware circuits and or processors, such as a microprocessor or a portion of a microprocessor, that requires software/firmware for operation, but the software may not be present when it is not needed for operation. As used herein, the term circuitry also covers an implementation of merely a hardware circuit or processor (s) or a portion of a hardware circuit or processor (s) and its (or their) accompanying software and/or firmware.

Generally, various embodiments of the present disclosure may be implemented in hardware or special purpose circuits, software, logic or any combination thereof. Some aspects may be implemented in hardware, while other aspects may be implemented in firmware or software which may be executed by a controller, microprocessor or other computing device. While various aspects of embodiments of the present disclosure are illustrated and described as block diagrams, flowcharts, or using some other pictorial representation, it will be appreciated that the blocks, apparatus, systems, techniques or methods described herein may be implemented in, as non-limiting examples, hardware, software, firmware, special purpose circuits or logic, general purpose hardware or controller or other computing devices, or some combination thereof.

The present disclosure also provides at least one computer program product tangibly stored on a non-transitory computer readable storage medium. The computer program product includes computer-executable instructions, such as those included in program modules, being executed in a device on a target real or virtual processor, to carry out the process or method as described above with reference to FIGs. 1 to 6. Generally, program modules include routines, programs, libraries, objects, classes, components, data structures, or the like that perform particular tasks or implement particular abstract data types. The functionality of the program modules may be combined or split between program modules as desired in various embodiments. Machine-executable instructions for program modules may be executed within a local or distributed device. In a distributed device, program modules may be located in both local and remote storage media.

Program code for carrying out methods of the present disclosure may be written in any combination of one or more programming languages. These program codes may be provided to a processor or controller of a general purpose computer, special purpose computer, or other programmable data processing apparatus, such that the program codes, when executed by the processor or controller, cause the functions/operations specified in the flowcharts and/or block diagrams to be implemented. The program code may execute entirely on a machine, partly on the machine, as a stand-alone software package, partly on the machine and partly on a remote machine or entirely on the remote machine or server.

The above program code may be embodied on a machine readable medium, which may be any tangible medium that may contain, or store a program for use by or in connection with an instruction execution system, apparatus, or device. The machine readable medium may be a machine readable signal medium or a machine readable storage medium. A machine readable medium may include but not limited to an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, or device, or any suitable combination of the foregoing. More specific examples of the machine readable storage medium would include an electrical connection having one or more wires, a portable computer diskette, a hard disk, a random access memory (RAM) , a read-only memory (ROM) , an erasable programmable read-only memory (EPROM or Flash memory) , an optical fiber, a portable compact disc read-only memory (CD-ROM) , an optical storage device, a magnetic storage device, or any suitable combination of the foregoing.

Further, while operations are depicted in a particular order, this should not be understood as requiring that such operations be performed in the particular order shown or in sequential order, or that all illustrated operations be performed, to achieve desirable results. In certain circumstances, multitasking and parallel processing may be advantageous. Likewise, while several specific implementation details are contained in the above discussions, these should not be construed as limitations on the scope of the present disclosure, but rather as descriptions of features that may be specific to particular embodiments. Certain features that are described in the context of separate embodiments may also be implemented in combination in a single embodiment. Conversely, various features that are described in the context of a single embodiment may also be implemented in multiple embodiments separately or in any suitable sub-combination.

Although the present disclosure has been described in language specific to structural features and/or methodological acts, it is to be understood that the present disclosure defined in the appended claims is not necessarily limited to the specific features or acts described above. Rather, the specific features and acts described above are disclosed as example forms of implementing the claims.

Claims

A terminal device, comprising:

a processor configured to cause the terminal device to:

determine that the terminal device is in a gap or is configured with a discontinuous reception (DRX) configuration; and

in accordance with a determination that a condition is satisfied, monitor a physical downlink control channel (PDCCH) , the condition comprising that a mobility procedure skipping a random access procedure is on-going.
The terminal device of claim 1, wherein the condition further comprises at least one of the following:

a PDCCH indicating a transmission addressed to a cell-radio network temporary identifier (C-RNTI) of a medium access control (MAC) entity of the terminal device has not been received from a serving cell; or

a configured grant for an initial uplink transmission is unavailable.
The terminal device of claim 1 or 2, wherein the terminal device is configured with the DRX configuration,

wherein the terminal device is further caused to: in accordance with a determination that the condition is satisfied, determine that the terminal device is in an active time for a DRX group, and

wherein the terminal device is caused to monitor the PDCCH by: monitoring the PDCCH in the active time.
The terminal device of claim 1 or 2, wherein the terminal device is configured with the DRX configuration, and the terminal device is caused to monitor the PDCCH by:

monitoring the PDCCH regardless of the DRX configuration.
The terminal device of claim 1 or 2, wherein the terminal device is in the gap, and the terminal device is caused to monitor the PDCCH by:

monitoring the PDCCH regardless of an occurrence of the gap, the gap comprising at least one of the following:

a measurement gap,

a multi-universal subscriber identity module (MUSIM) gap, or

a positioning reference signal (PRS) processing window.
The terminal device of claim 1 or 2, wherein the gap is a measurement gap, and the terminal device is further caused to determine that the condition is satisfied by:

determining that the condition is satisfied during an activated measurement gap.
The terminal device of claim 1 or 2, wherein the gap is a positioning reference signal (PRS) processing window, and the terminal device is further caused to determine that the condition is satisfied by:

determining that the condition is satisfied upon the PRS processing window is activated and a PRS has a priority higher than a downlink transmission.
A terminal device, comprising:

a processor configured to cause the terminal device to:

determine that a mobility procedure skipping a random access procedure is on-going; and

generate at least one of a medium access control (MAC) protocol data unit (PDU) or a cell-radio network temporary identifier (C-RNTI) MAC control element (CE) for an uplink grant for an initial uplink transmission to a target cell of the mobility procedure.
The terminal device of claim 8, wherein the terminal device is caused to generate the MAC PDU by:

in accordance with a determination that the terminal device is configured to skip an uplink transmission, generating the MAC PDU.
The terminal device of claim 8, wherein the terminal device is caused to generate the C-RNTI MAC CE by one of the following:

in accordance with a determination that the uplink grant is for the initial uplink transmission to the target cell, indicating a multiplexing and assembly entity of the terminal device to include the C-RNTI MAC CE in a subsequent uplink transmission;

in accordance with a determination that the uplink grant is for the initial uplink transmission to the target cell and no uplink data is to be transmitted, indicating the multiplexing and assembly entity of the terminal device to include the C-RNTI MAC CE in the subsequent uplink transmission; or

in accordance with a determination that the uplink grant is for the initial uplink transmission to the target cell, no uplink data is to be transmitted and the terminal device is configured to skip an uplink transmission, indicating the multiplexing and assembly entity of the terminal device to include the C-RNTI MAC CE in the subsequent uplink transmission.
A terminal device, comprising:

a processor configured to cause the terminal device to:

determine that a timer of a configured grant for a mobility procedure skipping a random access procedure expires; and

cancel using the configured grant for a transmission.
The terminal device of claim 11, wherein the terminal device is caused to cancel using the configured grant by at least one of the following:

clearing the configured grant;

suspending the configured grant;

considering the configured grant as invalid;

skipping or ignoring the configured grant; or

delivering no configured grant and hybrid automatic repeat request (HARQ) information associated with the configured grant to a HARQ entity of the terminal device.
The terminal device of claim 1 or 8 or 11, wherein the mobility procedure comprises at least one of the following:

a layer 1 or layer 2 triggered mobility (LTM) procedure;

a handover procedure; or

a primary secondary cell (PSCell) change procedure.