Patent Description:
Document: <NPL>), relates to SCG deactivation. Document: <NPL> R2-<NUM> Discussion on UE behaviour when SCG is deactivated. docx, (<NUM>), also relates to SCG deactivation procedure. Document: <NPL> - Measurement while the SCG is deactivated. doc, (<NUM>), relates to measurements while SCG is deactivated.

In NR, Secondary Cell Group (SCG) activation and/or SCG deactivation may be supported. For example, a wireless device may deactivate and/or activate an SCG.

In addition, in order to activate a deactivated SCG, RACH-less activation may be applied. Since a wireless device could activate an SCG without a RACH procedure, the resources for activating the SCG could be saved.

Therefore, studies for RACH-less activation in a wireless communication system are required.

In an aspect, a method according to claim <NUM> is provided.

In other aspects, an apparatus for implementing the above method according to claim <NUM> and a computer readable medium according to claim <NUM> are provided.

The present disclosure can have various advantageous effects.

According to some embodiments of the present disclosure, a wireless device could efficiently activate an SCG without a RACH procedure by maintaining a valid TA timer.

In other words, the valid TA timer remaining upon SCG reactivation may be an important factor for RACH-less activation. The reason that the wireless device sends the SCG failure information message may be to obtain reconfiguration for RACH-less activation, so the TA timer should continue to run during the SCG failure information procedure. Therefore, according to the present disclosure, skipping MAC reset during SCG failure information procedure in SCG deactivated state could be beneficial for RACH-less activation, that is, fast SCG activation.

In the case of BF, since a TA timer could be maintained, RACH-less activation could be efficiently performed.

Advantageous effects which can be obtained through specific embodiments of the present disclosure are not limited to the advantageous effects listed above. For example, there may be a variety of technical effects that a person having ordinary skill in the related art can understand and/or derive from the present disclosure. Accordingly, the specific effects of the present disclosure are not limited to those explicitly described herein, but may include various effects that may be understood or derived from the technical features of the present disclosure.

Also, parentheses used in the present disclosure may mean "for example". In detail, when it is shown as "control information (PDCCH)", "PDCCH" may be proposed as an example of "control information". In other words, "control information" in the present disclosure is not limited to "PDCCH", and "PDCCH" may be proposed as an example of "control information". In addition, even when shown as "control information (i.e., PDCCH)", "PDCCH" may be proposed as an example of "control information".

In addition, one of the most expected <NUM> use cases relates a function capable of smoothly connecting embedded sensors in all fields, i.e., mMTC. It is expected that the number of potential Internet-of-things (IoT) devices will reach <NUM> hundred million up to the year of <NUM>. An industrial IoT is one of categories of performing a main role enabling a smart city, asset tracking, smart utility, agriculture, and security infrastructure through <NUM>.

Mission critical application (e.g., e-health) is one of <NUM> use scenarios. A health part contains many application programs capable of enjoying benefit of mobile communication. A communication system may support remote treatment that provides clinical treatment in a faraway place. Remote treatment may aid in reducing a barrier against distance and improve access to medical services that cannot be continuously available in a faraway rural area. Remote treatment is also used to perform important treatment and save lives in an emergency situation. The wireless sensor network based on mobile communication may provide remote monitoring and sensors for parameters such as heart rate and blood pressure.

Referring to <FIG>, a first wireless device <NUM> and a second wireless device <NUM> may transmit/receive radio signals to/from an external device through a variety of RATs (e.g., LTE and NR). In <FIG>, {the first wireless device <NUM> and the second wireless device <NUM>} may correspond to at least one of {the wireless device 100a to 100f and the BS <NUM>}, {the wireless device 100a to 100f and the wireless device 100a to 100f} and/or {the BS <NUM> and the BS <NUM>} of <FIG>.

The processor(s) <NUM> may control the memory(s) <NUM> and/or the transceiver(s) <NUM> and may be configured to implement the descriptions, functions, procedures, suggestions, methods and/or operational flowcharts described in the present disclosure. The processor(s) <NUM> may receive radio signals including second information/signals through the transceiver(s) <NUM> and then store information obtained by processing the second information/signals in the memory(s) <NUM>. For example, the memory(s) <NUM> may store software code including commands for performing a part or the entirety of processes controlled by the processor(s) <NUM> or for performing the descriptions, functions, procedures, suggestions, methods and/or operational flowcharts described in the present disclosure. The transceiver(s) <NUM> may be interchangeably used with radio frequency (RF) unit(s). In the present disclosure, the first wireless device <NUM> may represent a communication modem/circuit/chip.

The processor(s) <NUM> may control the memory(s) <NUM> and/or the transceiver(s) <NUM> and may be configured to implement the descriptions, functions, procedures, suggestions, methods and/or operational flowcharts described in the present disclosure. For example, the memory(s) <NUM> may store software code including commands for performing a part or the entirety of processes controlled by the processor(s) <NUM> or for performing the descriptions, functions, procedures, suggestions, methods and/or operational flowcharts described in the present disclosure. In the present disclosure, the second wireless device <NUM> may represent a communication modem/circuit/chip.

As an example, one or more application specific integrated circuits (ASICs), one or more digital signal processors (DSPs), one or more digital signal processing devices (DSPDs), one or more programmable logic devices (PLDs), or one or more field programmable gate arrays (FPGAs) may be included in the one or more processors <NUM> and <NUM>. descriptions, functions, procedures, suggestions, methods and/or operational flowcharts disclosed in the present disclosure may be implemented using firmware or software and the firmware or software may be configured to include the modules, procedures, or functions. Firmware or software configured to perform the descriptions, functions, procedures, suggestions, methods and/or operational flowcharts disclosed in the present disclosure may be included in the one or more processors <NUM> and <NUM> or stored in the one or more memories <NUM> and <NUM> so as to be driven by the one or more processors <NUM> and <NUM>. The descriptions, functions, procedures, suggestions, methods and/or operational flowcharts disclosed in the present disclosure may be implemented using firmware or software in the form of code, commands, and/or a set of commands.

The one or more transceivers <NUM> and <NUM> may be connected to the one or more antennas <NUM> and <NUM> and the one or more transceivers <NUM> and <NUM> may be configured to transmit and receive user data, control information, and/or radio signals/channels, mentioned in the descriptions, functions, procedures, suggestions, methods and/or operational flowcharts disclosed in the present disclosure, through the one or more antennas <NUM> and <NUM>. In the present disclosure, the one or more antennas may be a plurality of physical antennas or a plurality of logical antennas (e.g., antenna ports).

The one or more transceivers <NUM> and <NUM> may convert received radio signals/channels, etc., from RF band signals into baseband signals in order to process received user data, control information, radio signals/channels, etc., using the one or more processors <NUM> and <NUM>. The one or more transceivers <NUM> and <NUM> may convert the user data, control information, radio signals/channels, etc., processed using the one or more processors <NUM> and <NUM> from the base band signals into the RF band signals. For example, the transceivers <NUM> and <NUM> can up-convert OFDM baseband signals to a carrier frequency by their (analog) oscillators and/or filters under the control of the processors <NUM> and <NUM> and transmit the up-converted OFDM signals at the carrier frequency. The transceivers <NUM> and <NUM> may receive OFDM signals at a carrier frequency and down-convert the OFDM signals into OFDM baseband signals by their (analog) oscillators and/or filters under the control of the transceivers <NUM> and <NUM>.

In the implementations of the present disclosure, a UE may operate as a transmitting device in uplink (UL) and as a receiving device in downlink (DL). In the implementations of the present disclosure, a BS may operate as a receiving device in UL and as a transmitting device in DL. Hereinafter, for convenience of description, it is mainly assumed that the first wireless device <NUM> acts as the UE, and the second wireless device <NUM> acts as the BS. For example, the processor(s) <NUM> connected to, mounted on or launched in the first wireless device <NUM> may be configured to perform the UE behavior according to an implementation of the present disclosure or control the transceiver(s) <NUM> to perform the UE behavior according to an implementation of the present disclosure. The processor(s) <NUM> connected to, mounted on or launched in the second wireless device <NUM> may be configured to perform the BS behavior according to an implementation of the present disclosure or control the transceiver(s) <NUM> to perform the BS behavior according to an implementation of the present disclosure.

The communication unit <NUM> may include a communication circuit <NUM> and transceiver(s) <NUM>. For example, the communication circuit <NUM> may include the one or more processors <NUM> and <NUM> of <FIG> and/or the one or more memories <NUM> and <NUM> of <FIG>. For example, the transceiver(s) <NUM> may include the one or more transceivers <NUM> and <NUM> of <FIG> and/or the one or more antennas <NUM> and <NUM> of <FIG>. The control unit <NUM> is electrically connected to the communication unit <NUM>, the memory <NUM>, and the additional components <NUM> and controls overall operation of each of the wireless devices <NUM> and <NUM>. For example, the control unit <NUM> may control an electric/mechanical operation of each of the wireless devices <NUM> and <NUM> based on programs/code/commands/information stored in the memory unit <NUM>.

As an example, the control unit <NUM> may be configured by a set of a communication control processor, an application processor (AP), an electronic control unit (ECU), a graphical processing unit, and a memory control processor. As another example, the memory <NUM> may be configured by a RAM, a DRAM, a ROM, a flash memory, a volatile memory, a non-volatile memory, and/or a combination thereof.

<FIG> shows another example of wireless devices to which implementations of the present disclosure is applied.

The first wireless device <NUM> may include at least one transceiver, such as a transceiver <NUM>, and at least one processing chip, such as a processing chip <NUM>. The processing chip <NUM> may include at least one processor, such a processor <NUM>, and at least one memory, such as a memory <NUM>. The memory <NUM> may be operably connectable to the processor <NUM>. The memory <NUM> may store various types of information and/or instructions. The memory <NUM> may store a software code <NUM> which implements instructions that, when executed by the processor <NUM>, perform the descriptions, functions, procedures, suggestions, methods and/or operational flowcharts disclosed in the present disclosure. For example, the software code <NUM> may implement instructions that, when executed by the processor <NUM>, perform the descriptions, functions, procedures, suggestions, methods and/or operational flowcharts disclosed in the present disclosure. For example, the software code <NUM> may control the processor <NUM> to perform one or more protocols. For example, the software code <NUM> may control the processor <NUM> may perform one or more layers of the radio interface protocol.

The second wireless device <NUM> may include at least one transceiver, such as a transceiver <NUM>, and at least one processing chip, such as a processing chip <NUM>. The processing chip <NUM> may include at least one processor, such a processor <NUM>, and at least one memory, such as a memory <NUM>. The memory <NUM> may be operably connectable to the processor <NUM>. The memory <NUM> may store various types of information and/or instructions. The memory <NUM> may store a software code <NUM> which implements instructions that, when executed by the processor <NUM>, perform the descriptions, functions, procedures, suggestions, methods and/or operational flowcharts disclosed in the present disclosure. For example, the software code <NUM> may implement instructions that, when executed by the processor <NUM>, perform the descriptions, functions, procedures, suggestions, methods and/or operational flowcharts disclosed in the present disclosure. For example, the software code <NUM> may control the processor <NUM> to perform one or more protocols. For example, the software code <NUM> may control the processor <NUM> may perform one or more layers of the radio interface protocol.

Referring to <FIG>, a UE <NUM> may correspond to the first wireless device <NUM> of <FIG> and/or the first wireless device <NUM> of <FIG>.

The processor <NUM> may be configured to implement the descriptions, functions, procedures, suggestions, methods and/or operational flowcharts disclosed in the present disclosure. The processor <NUM> may be configured to control one or more other components of the UE <NUM> to implement the descriptions, functions, procedures, suggestions, methods and/or operational flowcharts disclosed in the present disclosure. Layers of the radio interface protocol may be implemented in the processor <NUM>. The processor <NUM> may include ASIC, other chipset, logic circuit and/or data processing device. The processor <NUM> may be an application processor. The processor <NUM> may include at least one of a digital signal processor (DSP), a central processing unit (CPU), a graphics processing unit (GPU), a modem (modulator and demodulator). An example of the processor <NUM> may be found in SNAPDRAGON™ series of processors made by Qualcomm®, EXYNOS™ series of processors made by Samsung®, A series of processors made by Apple®, HELIO™ series of processors made by MediaTek®, ATOM™ series of processors made by Intel® or a corresponding next generation processor.

<FIG> and <FIG> show an example of protocol stacks in a 3GPP based wireless communication system to which implementations of the present disclosure is applied.

In particular, <FIG> illustrates an example of a radio interface user plane protocol stack between a UE and a BS and <FIG> illustrates an example of a radio interface control plane protocol stack between a UE and a BS. The control plane refers to a path through which control messages used to manage call by a UE and a network are transported. The user plane refers to a path through which data generated in an application layer, for example, voice data or Internet packet data are transported. Referring to <FIG>, the user plane protocol stack may be divided into Layer <NUM> (i.e., a PHY layer) and Layer <NUM>. Referring to <FIG>, the control plane protocol stack may be divided into Layer <NUM> (i.e., a PHY layer), Layer <NUM>, Layer <NUM> (e.g., an RRC layer), and a non-access stratum (NAS) layer. Layer <NUM>, Layer <NUM> and Layer <NUM> are referred to as an access stratum (AS).

In the 3GPP LTE system, the Layer <NUM> is split into the following sublayers: MAC, RLC, and PDCP. In the 3GPP NR system, the Layer <NUM> is split into the following sublayers: MAC, RLC, PDCP and SDAP. The PHY layer offers to the MAC sublayer transport channels, the MAC sublayer offers to the RLC sublayer logical channels, the RLC sublayer offers to the PDCP sublayer RLC channels, the PDCP sublayer offers to the SDAP sublayer radio bearers. The SDAP sublayer offers to <NUM> core network quality of service (QoS) flows.

In the 3GPP NR system, the main services and functions of the MAC sublayer include: mapping between logical channels and transport channels; multiplexing/de-multiplexing of MAC SDUs belonging to one or different logical channels into/from transport blocks (TB) delivered to/from the physical layer on transport channels; scheduling information reporting; error correction through hybrid automatic repeat request (HARQ) (one HARQ entity per cell in case of carrier aggregation (CA)); priority handling between UEs by means of dynamic scheduling; priority handling between logical channels of one UE by means of logical channel prioritization; padding. A single MAC entity may support multiple numerologies, transmission timings and cells. Mapping restrictions in logical channel prioritization control which numerology(ies), cell(s), and transmission timing(s) a logical channel can use.

Different kinds of data transfer services are offered by MAC. To accommodate different kinds of data transfer services, multiple types of logical channels are defined, i.e., each supporting transfer of a particular type of information. Each logical channel type is defined by what type of information is transferred. Logical channels are classified into two groups: control channels and traffic channels. Control channels are used for the transfer of control plane information only, and traffic channels are used for the transfer of user plane information only. Broadcast control channel (BCCH) is a downlink logical channel for broadcasting system control information, paging control channel (PCCH) is a downlink logical channel that transfers paging information, system information change notifications and indications of ongoing public warning service (PWS) broadcasts, common control channel (CCCH) is a logical channel for transmitting control information between UEs and network and used for UEs having no RRC connection with the network, and dedicated control channel (DCCH) is a point-to-point bi-directional logical channel that transmits dedicated control information between a UE and the network and used by UEs having an RRC connection. Dedicated traffic channel (DTCH) is a point-to-point logical channel, dedicated to one UE, for the transfer of user information. A DTCH can exist in both uplink and downlink. In downlink, the following connections between logical channels and transport channels exist: BCCH can be mapped to broadcast channel (BCH); BCCH can be mapped to downlink shared channel (DL-SCH); PCCH can be mapped to paging channel (PCH); CCCH can be mapped to DL-SCH; DCCH can be mapped to DL-SCH; and DTCH can be mapped to DL-SCH. In uplink, the following connections between logical channels and transport channels exist: CCCH can be mapped to uplink shared channel (UL-SCH); DCCH can be mapped to UL-SCH; and DTCH can be mapped to UL-SCH.

The RLC sublayer supports three transmission modes: transparent mode (TM), unacknowledged mode (UM), and acknowledged node (AM). The RLC configuration is per logical channel with no dependency on numerologies and/or transmission durations. In the 3GPP NR system, the main services and functions of the RLC sublayer depend on the transmission mode and include: transfer of upper layer PDUs; sequence numbering independent of the one in PDCP (UM and AM); error correction through ARQ (AM only); segmentation (AM and UM) and re-segmentation (AM only) of RLC SDUs; reassembly of SDU (AM and UM); duplicate detection (AM only); RLC SDU discard (AM and UM); RLC re-establishment; protocol error detection (AM only).

In the 3GPP NR system, the main services and functions of the PDCP sublayer for the user plane include: sequence numbering; header compression and decompression using robust header compression (ROHC); transfer of user data; reordering and duplicate detection; in-order delivery; PDCP PDU routing (in case of split bearers); retransmission of PDCP SDUs; ciphering, deciphering and integrity protection; PDCP SDU discard; PDCP re-establishment and data recovery for RLC AM; PDCP status reporting for RLC AM; duplication of PDCP PDUs and duplicate discard indication to lower layers. The main services and functions of the PDCP sublayer for the control plane include: sequence numbering; ciphering, deciphering and integrity protection; transfer of control plane data; reordering and duplicate detection; in-order delivery; duplication of PDCP PDUs and duplicate discard indication to lower layers.

In the 3GPP NR system, the main services and functions of the RRC sublayer include: broadcast of system information related to AS and NAS; paging initiated by 5GC or NG-RAN; establishment, maintenance and release of an RRC connection between the UE and NG-RAN; security functions including key management; establishment, configuration, maintenance and release of signaling radio bearers (SRBs) and data radio bearers (DRBs); mobility functions (including: handover and context transfer, UE cell selection and reselection and control of cell selection and reselection, inter-RAT mobility); QoS management functions; UE measurement reporting and control of the reporting; detection of and recovery from radio link failure; NAS message transfer to/from NAS from/to UE.

<FIG> shows a frame structure in a 3GPP based wireless communication system to which implementations of the present disclosure is applied.

The frame structure shown in <FIG> is purely exemplary and the number of subframes, the number of slots, and/or the number of symbols in a frame may be variously changed. In the 3GPP based wireless communication system, OFDM numerologies (e.g., subcarrier spacing (SCS), transmission time interval (TTI) duration) may be differently configured between a plurality of cells aggregated for one UE. For example, if a UE is configured with different SCSs for cells aggregated for the cell, an (absolute time) duration of a time resource (e.g., a subframe, a slot, or a TTI) including the same number of symbols may be different among the aggregated cells. Herein, symbols may include OFDM symbols (or CP-OFDM symbols), SC-FDMA symbols (or discrete Fourier transform-spread-OFDM (DFT-s-OFDM) symbols).

Referring to <FIG>, downlink and uplink transmissions are organized into frames. Each frame has Tf = <NUM> duration. Each frame is divided into two half-frames, where each of the half-frames has <NUM> duration. Each half-frame consists of <NUM> subframes, where the duration Tsf per subframe is <NUM>. Each subframe is divided into slots and the number of slots in a subframe depends on a subcarrier spacing. Each slot includes <NUM> or <NUM> OFDM symbols based on a cyclic prefix (CP). In a normal CP, each slot includes <NUM> OFDM symbols and, in an extended CP, each slot includes <NUM> OFDM symbols. The numerology is based on exponentially scalable subcarrier spacing Δf = <NUM>u*<NUM>.

Table <NUM> shows the number of OFDM symbols per slot Nslotsymb, the number of slots per frame Nframe,uslot, and the number of slots per subframe Nsubframe,uslot for the normal CP, according to the subcarrier spacing Δf = <NUM>u*<NUM>.

Table <NUM> shows the number of OFDM symbols per slot Nslotsymb, the number of slots per frame Nframe,uslot, and the number of slots per subframe Nsubframe,uslot for the extended CP, according to the subcarrier spacing Δf = <NUM>u*<NUM>.

A slot includes plural symbols (e.g., <NUM> or <NUM> symbols) in the time domain. For each numerology (e.g., subcarrier spacing) and carrier, a resource grid of Nsize,ugrid,x*NRBsc subcarriers and Nsubframe,usymb OFDM symbols is defined, starting at common resource block (CRB) Nstart,ugrid indicated by higher-layer signaling (e.g., RRC signaling), where Nsize,ugrid,x is the number of resource blocks (RBs) in the resource grid and the subscript x is DL for downlink and UL for uplink. NRBsc is the number of subcarriers per RB. In the 3GPP based wireless communication system, NRBsc is <NUM> generally. There is one resource grid for a given antenna port p, subcarrier spacing configuration u, and transmission direction (DL or UL). The carrier bandwidth Nsize,ugrid for subcarrier spacing configuration u is given by the higher-layer parameter (e.g., RRC parameter). Each element in the resource grid for the antenna port p and the subcarrier spacing configuration u is referred to as a resource element (RE) and one complex symbol may be mapped to each RE. Each RE in the resource grid is uniquely identified by an index k in the frequency domain and an index l representing a symbol location relative to a reference point in the time domain. In the 3GPP based wireless communication system, an RB is defined by <NUM> consecutive subcarriers in the frequency domain.

In the 3GPP NR system, RBs are classified into CRBs and physical resource blocks (PRBs). CRBs are numbered from <NUM> and upwards in the frequency domain for subcarrier spacing configuration u. The center of subcarrier <NUM> of CRB <NUM> for subcarrier spacing configuration u coincides with 'point A' which serves as a common reference point for resource block grids. In the 3GPP NR system, PRBs are defined within a bandwidth part (BWP) and numbered from <NUM> to NsizeBWP,i-<NUM>, where i is the number of the bandwidth part. The relation between the physical resource block nPRB in the bandwidth part i and the common resource block nCRB is as follows: nPRB = nCRB + NsizeBWP,i, where NsizeBWP,i is the common resource block where bandwidth part starts relative to CRB <NUM>. The BWP includes a plurality of consecutive RBs. A carrier may include a maximum of N (e.g., <NUM>) BWPs. A UE may be configured with one or more BWPs on a given component carrier. Only one BWP among BWPs configured to the UE can active at a time. The active BWP defines the UE's operating bandwidth within the cell's operating bandwidth.

In the present disclosure, the term "cell" may refer to a geographic area to which one or more nodes provide a communication system, or refer to radio resources. A "cell" as a geographic area may be understood as coverage within which a node can provide service using a carrier and a "cell" as radio resources (e.g., time-frequency resources) is associated with bandwidth which is a frequency range configured by the carrier. The "cell" associated with the radio resources is defined by a combination of downlink resources and uplink resources, for example, a combination of a DL component carrier (CC) and a UL CC. The cell may be configured by downlink resources only, or may be configured by downlink resources and uplink resources. Since DL coverage, which is a range within which the node is capable of transmitting a valid signal, and UL coverage, which is a range within which the node is capable of receiving the valid signal from the UE, depends upon a carrier carrying the signal, the coverage of the node may be associated with coverage of the "cell" of radio resources used by the node. Accordingly, the term "cell" may be used to represent service coverage of the node sometimes, radio resources at other times, or a range that signals using the radio resources can reach with valid strength at other times.

In CA, two or more CCs are aggregated. A UE may simultaneously receive or transmit on one or multiple CCs depending on its capabilities. CA is supported for both contiguous and non-contiguous CCs. When CA is configured, the UE only has one RRC connection with the network. At RRC connection establishment/re-establishment/handover, one serving cell provides the NAS mobility information, and at RRC connection re-establishment/handover, one serving cell provides the security input. This cell is referred to as the primary cell (PCell). The PCell is a cell, operating on the primary frequency, in which the UE either performs the initial connection establishment procedure or initiates the connection re-establishment procedure. Depending on UE capabilities, secondary cells (SCells) can be configured to form together with the PCell a set of serving cells. An SCell is a cell providing additional radio resources on top of special cell (SpCell). The configured set of serving cells for a UE therefore always consists of one PCell and one or more SCells. For dual connectivity (DC) operation, the term SpCell refers to the PCell of the master cell group (MCG) or the primary SCell (PSCell) of the secondary cell group (SCG). An SpCell supports PUCCH transmission and contention-based random access, and is always activated. The MCG is a group of serving cells associated with a master node, comprised of the SpCell (PCell) and optionally one or more SCells. The SCG is the subset of serving cells associated with a secondary node, comprised of the PSCell and zero or more SCells, for a UE configured with DC. For a UE in RRC_CONNECTED not configured with CA/DC, there is only one serving cell comprised of the PCell. For a UE in RRC_CONNECTED configured with CA/DC, the term "serving cells" is used to denote the set of cells comprised of the SpCell(s) and all SCells. In DC, two MAC entities are configured in a UE: one for the MCG and one for the SCG.

<FIG> shows a data flow example in the 3GPP NR system to which implementations of the present disclosure is applied.

Referring to <FIG>, "RB" denotes a radio bearer, and "H" denotes a header. Radio bearers are categorized into two groups: DRBs for user plane data and SRBs for control plane data. The MAC PDU is transmitted/received using radio resources through the PHY layer to/from an external device. The MAC PDU arrives to the PHY layer in the form of a transport block.

In the PHY layer, the uplink transport channels UL-SCH and RACH are mapped to their physical channels PUSCH and PRACH, respectively, and the downlink transport channels DL-SCH, BCH and PCH are mapped to PDSCH, PBCH and PDSCH, respectively. In the PHY layer, uplink control information (UCI) is mapped to PUCCH, and downlink control information (DCI) is mapped to PDCCH. A MAC PDU related to UL-SCH is transmitted by a UE via a PUSCH based on an UL grant, and a MAC PDU related to DL-SCH is transmitted by a BS via a PDSCH based on a DL assignment.

Hereinafter, technical features related to SCG failure information are described. Section <NUM>. <NUM> of 3GPP TS <NUM> v16. <NUM> may be referred.

<FIG> shows an example of an SCG failure information procedure.

Referring to <FIG>, the network may provide an RRC reconfiguration to the UE. The UE may transmit an SCG Failure Information to the network.

The purpose of this procedure is to inform E-UTRAN or NR MN about an SCG failure the UE has experienced i.e. SCG radio link failure, failure of SCG reconfiguration with sync, SCG configuration failure for RRC message on SRB3, SCG integrity check failure, and consistent uplink LBT failures on PSCell for operation with shared spectrum channel access.

A UE initiates the procedure to report SCG failures when neither MCG nor SCG transmission is suspended and when one of the following conditions is met:.

Upon initiating the procedure, the UE shall:.

Hereinafter, technical features related to MAC Reset are described. Section <NUM> of 3GPP TS <NUM> v16. <NUM> may be referred.

If a reset of the MAC entity is requested by upper layers, the MAC entity shall:.

If a Sidelink specific reset of the MAC entity is requested for a PC5-RRC connection by upper layers, the MAC entity shall:.

Hereinafter, technical features related to Beam Failure Detection and Recovery procedure are described. Section <NUM> of 3GPP TS <NUM> v16. <NUM> may be referred.

The MAC entity may be configured by RRC per Serving Cell with a beam failure recovery procedure which is used for indicating to the serving gNB of a new SSB or CSI-RS when beam failure is detected on the serving SSB(s)/CSI-RS(s). Beam failure is detected by counting beam failure instance indication from the lower layers to the MAC entity. If beamFailureRecoveryConfig is reconfigured by upper layers during an ongoing Random Access procedure for beam failure recovery for SpCell, the MAC entity shall stop the ongoing Random Access procedure and initiate a Random Access procedure using the new configuration.

RRC configures the following parameters in the BeamFailureRecoveryConfig, BeamFailureRecoverySCellConfig, and the RadioLinkMonitoringConfig for the Beam Failure Detection and Recovery procedure:.

The following UE variables are used for the beam failure detection procedure:.

The MAC entity shall for each Serving Cell configured for beam failure detection:.

All BFRs triggered for an SCell shall be cancelled when a MAC PDU is transmitted and this PDU includes a BFR MAC CE or Truncated BFR MAC CE which contains beam failure information of that SCell.

Hereinafter, technical features related to Activation/Deactivation of SCells are described. Section <NUM> of 3GPP TS <NUM> v16. <NUM> may be referred.

If the MAC entity is configured with one or more SCells, the network may activate and deactivate the configured SCells. Upon configuration of an SCell, the SCell is deactivated unless the parameter sCellState is set to activated for the SCell by upper layers.

The configured SCell(s) is activated and deactivated by:.

The MAC entity shall for each configured SCell:.

HARQ feedback for the MAC PDU containing SCell Activation/Deactivation MAC CE shall not be impacted by PCell, PSCell and PUCCH SCell interruptions due to SCell activation/deactivation.

When SCell is deactivated, the ongoing Random Access procedure on the SCell, if any, is aborted.

Hereinafter, technical features related to SCG activation in NR are described.

For example, when the SCG activation is indicated to the UE via the MCG, the UE behaviour may include one or more of the following options.

Related to option <NUM>, for example, the UE may decide not to perform random access (one option to be selected):.

In addition, for option 2a): in the SCG deactivated state, the UE may monitor some DL beams (if the same as BFD or RLM) and, if the UE sees that the beams are not good enough, the UE either (one of the options to be selected): (<NUM>) will perform random access upon reception of the next SCG activation indication from the MCG, and (<NUM>) will report measurement results via the MCG and wait for reconfiguration.

For example, the UE may not perform RACH after TAT expires while the SCG is deactivated.

At PSCell addition/change/HO/RRC resume, in case the SCG state is configured as deactivated, the UE may not perform random access. If the network wants the UE to perform random access, it can indicate the SCG as activated and deactivate it after the random access by RRC or MAC CE if supported.

Network should ensure PDCP entity and RLC entity are "cleaned" when doing SCG (de)activation, e.g. using PDCP data recovery and RLC re-establishment or RLC entity release.

For example, upon SCG deactivation, UE may instruct the SCG MAC entity to perform partial MAC reset.

For example, upon SCG deactivation, UE may keep all timeAlignmentTimers (e.g. associated with the PTAG and STAG) running, if configured.

For example, UE implementation may ensure that data loss for pre-processed data of UM DRB inside UE (e.g. due to RLC/PDCP re-establishment) is avoided upon SCG activation.

For example, upon SCG deactivation, the reordering delay for UM DRB can be resolved by UE implementation.

For example, UE may not suspend SRB3 upon SCG deactivation.

For example, the old RRC message for SRB3 may be discarded upon SCG deactivation (i.e. trigger the PDCP entity to perform SDU discard and re-establish the RLC entity for SRB3).

For example, upon BF while the SCG is deactivated: UE may indicate BF to NW via RRC (e.g. so the network can reconfigure the UE to keep the PSCell and allow RACH-less activation (by changing BFD RS), or change the PSCell or release the SCG). If the network does not reconfigure the UE and activates the SCG, RACH will be used.

For example, UE may stop (if running) all timers except beamFailureDetectionTimer associated with PSCell and timeAlignmentTimers upon SCG deactivation as a part of partial MAC reset.

For example, if BFD is not configured for deactivated SCG, UE may stop (if running) beamFailureDetectionTimer associated with PSCell upon SCG deactivation as a part of partial MAC reset.

As described above, in NR, Secondary Cell Group (SCG) activation and/or SCG deactivation may be supported. For example, a wireless device may deactivate and/or activate an SCG.

Hereinafter, a method for RACH-less activation in a wireless communication system, according to some embodiments of the present disclosure, will be described with reference to the following drawings.

The following drawings are created to explain specific embodiments of the present disclosure. The names of the specific devices or the names of the specific signals/messages/fields shown in the drawings are provided by way of example, and thus the technical features of the present disclosure are not limited to the specific names used in the following drawings. Herein, a wireless device may be referred to as a user equipment (UE).

<FIG> shows an example of a method for RACH-less activation in a wireless communication system, according to some embodiments of the present disclosure.

In particular, <FIG> shows an example of a method performed by a wireless device in a wireless communication system.

In step S1101, a wireless device deactivates a Secondary Cell Group (SCG).

For example, the wireless device may receive, from a network, a configuration for beam failure detection for the SCG. For example, the configuration for beam failure detection may be received before deactivating the SCG.

For example, the wireless device may keep the time alignment timer (TAT) running, upon deactivating the SCG. In other words, even though deactivating the SCG, the wireless device may not stop the TAT, since the beam failure detection is configured.

For example, Physical Downlink Control Channel (PDCCH) monitoring and/or Physical Uplink Shared Channel (PUSCH) transmission for the SCG may be not performed by the wireless device, while the SCG is deactivated.

In step S1102, a wireless device detects a beam failure of a Primary SCell (PSCell) in the SCG.

For example, the lower layers (for example, physical layer) of the wireless device may detect a beam failure instance of the PSCell and indicate the beam failure instance to the upper layers (For example, a MAC layer).

In step S1103, a wireless device initiates a SCG failure information procedure to report the SCG failure.

That is, the wireless device initiates the SCG failure information procedure upon detecting the beam failure.

In step S1104, a wireless device skips a Media Access Control (MAC) reset procedure. The MAC reset procedure includes stopping a Time Alignment Timer (TAT) for the SCG.

In other words, in the SCG failure information procedure, the wireless device may not perform the MAC reset.

If the wireless device perform the MAC reset in the SCG failure information procedure, the TAT may be expired. Since the MAC reset procedure, which is not for the SCG deactivation, includes a step of stopping the TAT for the SCG. However, according to step S1104, since the wireless device skips the MAC reset procedure, the TAT could be maintained.

In step S1105, a wireless device transmits SCG failure information.

For example, a wireless device may transmit SCG failure information via a Master Cell Group (MCG).

In other words, in the SCG failure information procedure, the wireless device may transmit SCG failure information via the Master Cell Group (MCG) to the network.

In step S1106, a wireless device determines that a random access procedure is not needed for activation of the SCG, based on the TAT being not expired.

For example, the wireless device activates the SCG based on the TAT without performing a random access procedure.

In other words, the wireless device performs the RACH-less activation while the TAT is running.

According to some embodiments of the present disclosure, the wireless device may configure a beam failure instance counter and a beam failure detection timer. The wireless device may increment the beam failure instance counter by <NUM>, when the lower layers of the wireless device detects a beam failure instance for the PSCell. For example, the wireless device may perform the RACH-less activation for the PSCell, when (<NUM>) the value of the beam failure instance counter for the PSCell is less than a maximum value and (<NUM>) the TAT associated with a Primary Timing Advance Group (PTAG) related to the PSCell is running.

For other example, when (<NUM>) the value of the beam failure instance counter for the PSCell is greater than or equal to a maximum value, or (<NUM>) the TAT associated with a PTAG related to the PSCell is not running, the wireless device may not perform the RACH-less activation for the PSCell and determine that the random access procedure is needed for SCG activation.

According to some embodiments of the present disclosure, the wireless device may receive, from a network, a configuration for radio link failure detection for the SCG. For example, the configuration for radio link failure detection may be received before deactivating the SCG, as in step S1101.

The wireless device may detect a radio link failure of the PSCell in the SCG.

The wireless device may initiate a SCG failure information procedure to report the SCG failure, as in step S1103.

The wireless device may perform a MAC reset procedure including the step of stopping a TAT for the SCG. That is, the wireless device may perform the MAC reset procedure in the SCG failure information procedure. Then, the TAT for the SCG may be expired upon performing the MAC reset procedure.

In this example, the wireless device may determine that a random access procedure is needed for activation of the SCG, based on the TAT is expired.

The wireless device may activate the SCG by performing a random access procedure. In other words, the random access procedure may be needed for activation of the SCG, after detecting the radio link failure.

According to some embodiments of the present disclosure, a wireless device may receive, from a network, (<NUM>) a radio resource control (RRC) Reconfiguration message and/or (<NUM>) an RRC Resume message including the RRC Reconfiguration message. The wireless device may perform the activation of the SCG.

For example, upon receiving the RRC Reconfiguration message, the wireless device may initiate the activation of the SCG.

For example, the wireless device may skip to perform the random access procedure for the activation of the SCG, based on the RRC Reconfiguration message not including a reconfigurationWithSync.

For example, the RRC Reconfiguration message may include cell group configuration (for example, cell group configuration for the SCG). The cell group configuration may include special cell (spCell) configuration (for example the spCell configuration for the PSCell). The spCell configuration may or may not include the reconfigurationWithSync.

For example, the wireless device may skip to perform the random access procedure for the activation of the SCG, based on (<NUM>) beam failure detection (BFD) and radio link monitoring (RLM) being configured before reception of the RRC Reconfiguration message, and (<NUM>) determining that the random access procedure is not needed for activation of the SCG.

For other example, the wireless device may skip to perform the random access procedure for the activation of the SCG, based on (<NUM>) the RRC Reconfiguration message not including a reconfigurationWithSync, (<NUM>) beam failure detection (BFD) and radio link monitoring (RLM) being configured before reception of the RRC Reconfiguration message, and (<NUM>) the determination that a random access procedure is not needed for activation of the SCG, as in step S1106.

According to some embodiments of the present disclosure, the wireless device may be in communication with at least one of a user equipment, a network, or an autonomous vehicle other than the wireless device.

Hereinafter, embodiments of a method for skipping MAC reset during SCG failure information procedure in a wireless communication system are described.

For example, when a UE is configured for NR-DC operation, an SCG could be deactivated for power saving. In SCG deactivated state, there may be no PDCCH monitoring and PUSCH transmission in SCG. However, for the RACH-less activation, the UE may keep all SCG timeAlignmentTimers (TAT) running upon SCG deactivation and may perform Radio Link Monitoring (RLM)/Beam Failure Detection (BFD)/Radio Resource Management (RRM) in SCG. When SCG is activated, if neither Radio Link Failure (RLF) nor Beam Failure (BF) occurs while SCG is deactivated, and if the TA timer is running, the UE may perform RACH-less activation.

If BF occurs while the SCG is deactivated, the UE may indicate BF to NW via SCG failure information message, so that the network can reconfigure the UE to keep the PSCell and allow RACH-less activation by changing BFD RS.

However, since the SCG failure information message procedure has a MAC reset procedure, which includes the expiration of the TA timer, the UE cannot perform RACH-less activation without a valid TA timer. Therefore, skipping SCG MAC reset in SCG deactivated state may be beneficial for RACH-less activation, that is, fast SCG activation.

According to some embodiments of the present disclosure, in order to reduce UE power consumption in NR-DC operation, the UE may be configured to deactivate SCG. For the fast SCG re-activation, the UE may be configured to perform RLM or BFD in deactivated SCG. When the UE sends SCG failure information message via MCG due to RLF or BF, the UE may check the SCG state to determine whether to skip SCG MAC reset.

When the UE sends SCG failure information message via MCG due to RLF or BF, it checks the SCG state. If the SCG is in the deactivated state, MAC (that is, a MAC entity or a MAC layer of the UE) related to the SCG may be not reset. Otherwise, MAC related to the SCG may be reset. For example, the MAC related to the SCG may be referred as SCG MAC (that is, SCG MAC entity).

For example, upon RLF occurring in SCG, the UE may initiate SCG failure information procedure.

If the SCG is in the deactivated state, MAC related to the SCG may be not reset.

If the SCG is in the activated state, MAC related to the SCG may be reset.

For example, upon BF occurring in SCG, the UE may initiate SCG failure information procedure.

For example, upon BF occurring in SCG, the UE may determine whether to initiate SCG failure information procedure based on the SCG state.

If the SCG is in the deactivated state, the UE may initiate SCG failure information procedure, and MAC related to the SCG may be not reset.

If the SCG is in the activated state, the UE may not initiate SCG failure information procedure.

When the UE sends SCG failure information message via MCG due to BF, it may check the SCG state. If the SCG is in the deactivated state, MAC related to the SCG may be not reset. Otherwise, MAC related to the SCG may be reset.

For example, upon BF occurring in SCG, the may UE determine whether to initiate SCG failure information procedure based on the SCG state.

If the SCG is in the deactivated state, the UE may initiate SCG failure information procedure. MAC related to the SCG may be not reset.

When the UE sends SCG failure information message via MCG due to RLF, it may check the SCG state. If the SCG is in the deactivated state, MAC related to the SCG may be not reset. Otherwise, MAC related to the SCG may be reset.

<FIG> shows an example of a method for skipping MAC reset during SCG failure information procedure in a wireless communication system, according to some embodiments of the present disclosure.

In step S1201, UE may detect a failure in SCG while the SCG is in deactivated state;.

In step S1202, UE may initiating SCG failure information procedure.

In step S1203, UE may suspend transmission in the SCG.

In step S1204, UE may transmit SCG failure information on MCG.

In step S1205, UE may keep TA timer based on the SCG being in the deactivate state.

In other words, the SCG failure information procedure may include (<NUM>) suspending transmission in the SCG; (<NUM>) transmitting SCG failure information on MCG; and (<NUM>) keeping TA timer based on the SCG being in the deactivate state.

For example, MAC related to the SCG (that is, an SCG MAC entity or an SCG MAC layer) may be not reset based on the SCG being in the deactivated state.

<FIG> shows an example of UE operations for RACH-less activation in a wireless communication system are described.

In step S1301, UE may perform operations related to deactivation of SCG.

For example, the network may deactivate the configured SCG.

The MAC entity (that is, the MAC entity of the UE) shall for the configured SCG:.

That is, UE may reset MAC upon deactivation of SCG. In other words, UE may initiate MAC reset procedure based on the deactivation of SCG.

For example, the MAC reset procedure for SCG deactivation is as below. In other words, UE may perform the following operation in the MAC reset procedure for SCG deactivation.

For example, an example of a MAC Reset procedure is as below.

That is, in the MAC reset procedure for SCG deactivation, if beam failure detection is configured for the UE, the UE may stop all timers except beamFailureDetectionTimer associated with PSCell and timeAlignmentTimers. In other words, in the MAC reset procedure for SCG deactivation, the UE may maintain the timeAlignmentTimers (TATs).

In step S <NUM>, UE may initiate an SCG failure information procedure, while the SCG is deactivated.

For example, UE may initiate the SCG failure information procedure based on detecting a beam failure.

In step S <NUM>, the UE may skip a MAC reset procedure in the SCG failure information procedure. For example, the MAC reset procedure, which is not initiated upon deactivation of the SCG, may include stopping a TAT for the SCG.

For example, when the UE initiate the SCG failure information procedure based on detecting beam failure of the SCG, the UE may skip the MAC reset procedure, which includes stopping a TAT for the SCG in the SCG failure information procedure.

For example, the purpose of the SCG failure information procedure procedure is to inform E-UTRAN or NR MN about an SCG failure the UE has experienced i.e. SCG radio link failure, failure of SCG reconfiguration with sync, SCG configuration failure for RRC message on SRB3, SCG integrity check failure, and consistent uplink LBT failures on PSCell for operation with shared spectrum channel access.

In step S1304, UE may perform operations related to activation of SCG. For example, the UE may perform the RACH-less activation for the deactivated SCG, since the TAT is not expired. In other words, the UE may activate the SCG according to the timing for direct SCG activation without a Random Access Procedure.

For example, the network may activate the configured SCG.

According to some embodiments of the present disclosure, the upper layers of the UE may indicate that SCG is activated upon receiving an RRC Reconfiguration.

For example, the UE shall perform the following actions upon reception of the RRCReconfiguration, or upon execution of the conditional reconfiguration (CHO, CPA or CPC):.

For example, Upon initiating the SCG activation as described above, the UE shall:.

<FIG> shows an example of Base Station (BS) operations for RACH-less activation in a wireless communication system, according to some embodiments of the present disclosure.

In step S1401, aBS may transmit, to a wireless device, a configuration for beam failure detection for a SCG.

In step S1402, a BS may deactivate the SCG.

In step S1403, a BS may receive, from the wireless device, SCG Failure Information for the SCG via a Master Cell Group (MCG).

In step S1404, a BS may activate the SCG without a random access procedure.

Some of the detailed steps shown in the examples of <FIG>, <FIG>, <FIG>, and <FIG> may not be essential steps and may be omitted. In addition to the steps shown in <FIG>, <FIG>, <FIG>, and <FIG>, other steps may be added, and the order of the steps may vary. Some of the above steps may have their own technical meaning.

Hereinafter, an apparatus for RACH-less activation in a wireless communication system, according to some embodiments of the present disclosure, will be described. Herein, the apparatus may be a wireless device (<NUM> or <NUM>) in <FIG>, <FIG>, and <FIG>.

For example, a wireless device may perform the methods described above. The detailed description overlapping with the above-described contents could be simplified or omitted.

Referring to <FIG>, a wireless device <NUM> may include a processor <NUM>, a memory <NUM>, and a transceiver <NUM>.

According to some embodiments of the present disclosure, the processor <NUM> may be configured to be coupled operably with the memory <NUM> and the transceiver <NUM>.

The processor <NUM> may be configured to deactivate a Secondary Cell Group (SCG). The processor <NUM> may be configured to detect a beam failure of a Primary SCell (PSCell) in the SCG. The processor <NUM> may be configured to initiate a SCG failure information procedure to report the SCG failure. The processor <NUM> may be configured to skip a Media Access Control (MAC) reset procedure. For example, the MAC reset procedure may include stopping a Time Alignment Timer (TAT) for the SCG. The processor <NUM> may be configured to control the transceiver <NUM> to transmit SCG failure information via a Master Cell Group (MCG). The processor <NUM> may be configured to determine that a random access procedure is not needed for activation of the SCG, based on the TAT being not expired.

For example, the processor <NUM> may be configured to keep the TAT running, upon deactivating the SCG.

For example, the processor <NUM> may be configured to activate the SCG based on the TAT without performing a random access procedure.

For example, the processor <NUM> may be configured to control the transceiver <NUM> to receive, from a network, a configuration for beam failure detection.

According to some embodiments of the present disclosure, the processor <NUM> may be configured to detect a radio link failure of the PSCell in the SCG, initiate a SCG failure information procedure to report the SCG failure, and perform a MAC reset procedure, wherein the MAC reset procedure includes stopping a TAT for the SCG.

The processor <NUM> may be configured to determine that a random access procedure is needed for activation of the SCG, based on the TAT is expired.

The processor <NUM> may be configured to activate the SCG by performing a random access procedure.

For example, the processor <NUM> may be configured to control the transceiver <NUM> to receive, from a network, a configuration for radio link failure detection.

For example, the TAT may include a Time Alignment Timer associated with a Primary Timing Advance Group (PTAG).

For example, the processor <NUM> may be configured to configure a beam failure instance counter for the PSCell. The processor <NUM> may be configured to increment the beam failure instance counter based on detecting a beam failure instance for the PSCell. In this case, it may be determined that the random access procedure is not needed for activation of the SCG, based on the value of the beam failure instance counter for the PSCell being less than a maximum value.

For example, the processor <NUM> may be configured to control the transceiver <NUM> to receive, from a network, (<NUM>) a radio resource control (RRC) Reconfiguration message and/or (<NUM>) an RRC Resume message including the RRC Reconfiguration message. The processor <NUM> may be configured to perform the activation of the SCG.

For example, the processor <NUM> may be configured to skip to perform the random access procedure for the activation of the SCG, based on the RRC Reconfiguration message not including a reconfigurationWithSync.

For example, the processor <NUM> may be configured to skip to perform the random access procedure for the activation of the SCG, based on (<NUM>) beam failure detection (BFD) and radio link monitoring (RLM) being configured before reception of the RRC Reconfiguration message, and (<NUM>) determining that the random access procedure is not needed for activation of the SCG.

For example, the processor <NUM> may be configured to control the transceiver <NUM> to be in communication with at least one of a user equipment, a network, or an autonomous vehicle other than the wireless device.

Hereinafter, a processor for a wireless device for RACH-less activation in a wireless communication system, according to some embodiments of the present disclosure, will be described.

The processor may be configured to control the wireless device to deactivate a Secondary Cell Group (SCG). The processor may be configured to control the wireless device to detect a beam failure of a Primary SCell (PSCell) in the SCG. The processor may be configured to control the wireless device to initiate a SCG failure information procedure to report the SCG failure. The processor may be configured to control the wireless device to skip a Media Access Control (MAC) reset procedure. For example, the MAC reset procedure may include stopping a Time Alignment Timer (TAT) for the SCG. The processor may be configured to control the wireless device to transmit SCG failure information via a Master Cell Group (MCG). The processor may be configured to control the wireless device to determine that a random access procedure is not needed for activation of the SCG, based on the TAT being not expired.

For example, the processor may be configured to control the wireless device to keep the TAT running, upon deactivating the SCG.

For example, the processor may be configured to control the wireless device to activate the SCG based on the TAT without performing a random access procedure.

For example, the processor may be configured to control the wireless device to receive, from a network, a configuration for beam failure detection.

According to some embodiments of the present disclosure, the processor may be configured to control the wireless device to detect a radio link failure of the PSCell in the SCG, initiate a SCG failure information procedure to report the SCG failure, and perform a MAC reset procedure, wherein the MAC reset procedure includes stopping a TAT for the SCG.

The processor may be configured to control the wireless device to determine that a random access procedure is needed for activation of the SCG, based on the TAT is expired.

The processor may be configured to control the wireless device to activate the SCG by performing a random access procedure.

For example, the processor may be configured to control the wireless device to receive, from a network, a configuration for radio link failure detection.

For example, the processor may be configured to control the wireless device to configure a beam failure instance counter for the PSCell. The processor may be configured to control the wireless device to increment the beam failure instance counter based on detecting a beam failure instance for the PSCell. In this case, it may be determined that the random access procedure is not needed for activation of the SCG, based on the value of the beam failure instance counter for the PSCell being less than a maximum value.

For example, the processor may be configured to control the wireless device to receive, from a network, (<NUM>) a radio resource control (RRC) Reconfiguration message and/or (<NUM>) an RRC Resume message including the RRC Reconfiguration message. The processor may be configured to control the wireless device to perform the activation of the SCG.

For example, the processor may be configured to control the wireless device to skip to perform the random access procedure for the activation of the SCG, based on the RRC Reconfiguration message not including a reconfigurationWithSync.

For example, the processor may be configured to control the wireless device to skip to perform the random access procedure for the activation of the SCG, based on (<NUM>) beam failure detection (BFD) and radio link monitoring (RLM) being configured before reception of the RRC Reconfiguration message, and (<NUM>) determining that the random access procedure is not needed for activation of the SCG.

For example, the processor may be configured to control the wireless device to be in communication with at least one of a user equipment, a network, or an autonomous vehicle other than the wireless device.

Hereinafter, a non-transitory computer-readable medium has stored thereon a plurality of instructions for RACH-less activation in a wireless communication system, according to some embodiments of the present disclosure, will be described.

According to some embodiment of the present disclosure, the technical features of the present disclosure could be embodied directly in hardware, in a software executed by a processor, or in a combination of the two. For example, a method performed by a wireless device in a wireless communication may be implemented in hardware, software, firmware, or any combination thereof. For example, a software may reside in RAM memory, flash memory, ROM memory, EPROM memory, EEPROM memory, registers, hard disk, a removable disk, a CD-ROM, or any other storage medium.

Some example of storage medium is coupled to the processor such that the processor can read information from the storage medium. For other example, the processor and the storage medium may reside as discrete components.

The computer-readable medium may include a tangible and non-transitory computer-readable storage medium.

For example, non-transitory computer-readable media may include random access memory (RAM) such as synchronous dynamic random access memory (SDRAM), read-only memory (ROM), non-volatile random access memory (NVRAM), electrically erasable programmable read-only memory (EEPROM), FLASH memory, magnetic or optical data storage media, or any other medium that can be used to store instructions or data structures. Non-transitory computer-readable media may also include combinations of the above.

In addition, the method described herein may be realized at least in part by a computer-readable communication medium that carries or communicates code in the form of instructions or data structures and that can be accessed, read, and/or executed by a computer.

According to some embodiment of the present disclosure, a non-transitory computer-readable medium has stored thereon a plurality of instructions. The stored a plurality of instructions may be executed by a processor of a wireless device.

The stored a plurality of instructions may cause the wireless device to deactivate a Secondary Cell Group (SCG). The stored a plurality of instructions may cause the wireless device to detect a beam failure of a Primary SCell (PSCell) in the SCG. The stored a plurality of instructions may cause the wireless device to initiate a SCG failure information procedure to report the SCG failure. The stored a plurality of instructions may cause the wireless device to skip a Media Access Control (MAC) reset procedure. For example, the MAC reset procedure may include stopping a Time Alignment Timer (TAT) for the SCG. The stored a plurality of instructions may cause the wireless device to transmit SCG failure information via a Master Cell Group (MCG). The stored a plurality of instructions may cause the wireless device to determine that a random access procedure is not needed for activation of the SCG, based on the TAT being not expired.

For example, the stored a plurality of instructions may cause the wireless device to keep the TAT running, upon deactivating the SCG.

For example, the stored a plurality of instructions may cause the wireless device to activate the SCG based on the TAT without performing a random access procedure.

For example, the stored a plurality of instructions may cause the wireless device to receive, from a network, a configuration for beam failure detection.

According to some embodiments of the present disclosure, the stored a plurality of instructions may cause the wireless device to detect a radio link failure of the PSCell in the SCG, initiate a SCG failure information procedure to report the SCG failure, and perform a MAC reset procedure, wherein the MAC reset procedure includes stopping a TAT for the SCG.

The stored a plurality of instructions may cause the wireless device to determine that a random access procedure is needed for activation of the SCG, based on the TAT is expired.

The stored a plurality of instructions may cause the wireless device to activate the SCG by performing a random access procedure.

For example, the stored a plurality of instructions may cause the wireless device to receive, from a network, a configuration for radio link failure detection.

For example, the stored a plurality of instructions may cause the wireless device to configure a beam failure instance counter for the PSCell. The stored a plurality of instructions may cause the wireless device to increment the beam failure instance counter based on detecting a beam failure instance for the PSCell. In this case, it may be determined that the random access procedure is not needed for activation of the SCG, based on the value of the beam failure instance counter for the PSCell being less than a maximum value.

For example, the stored a plurality of instructions may cause the wireless device to receive, from a network, (<NUM>) a radio resource control (RRC) Reconfiguration message and/or (<NUM>) an RRC Resume message including the RRC Reconfiguration message. The stored a plurality of instructions may cause the wireless device to perform the activation of the SCG.

For example, the stored a plurality of instructions may cause the wireless device to skip to perform the random access procedure for the activation of the SCG, based on the RRC Reconfiguration message not including a reconfigurationWithSync.

For example, the stored a plurality of instructions may cause the wireless device to skip to perform the random access procedure for the activation of the SCG, based on (<NUM>) beam failure detection (BFD) and radio link monitoring (RLM) being configured before reception of the RRC Reconfiguration message, and (<NUM>) determining that the random access procedure is not needed for activation of the SCG.

According to some embodiments of the present disclosure, the stored a plurality of instructions may cause the wireless device to be in communication with at least one of a user equipment, a network, or an autonomous vehicle other than the wireless device.

Hereinafter, a base station (BS) for RACH-less activation in a wireless communication system, according to some embodiments of the present disclosure, will be described.

The BS may include a transceiver, a memory, and a processor operatively coupled to the transceiver and the memory.

The processor may be configured to control the transceiver to transmit, to a wireless device, a configuration for beam failure detection for a SCG. The processor may be configured to deactivate the SCG for the wireless device. The processor may be configured to receive, from the wireless device, SCG Failure Information for the SCG via a Master Cell Group (MCG).

The processor may be configured to activate the SCG for the wireless device without a random access procedure.

For example, in the case of BF, since a TA timer could be maintained, RACH-less activation could be efficiently performed.

According to some embodiments of the present disclosure, a wireless network system could provide an efficient solution for the RACH-less activation procedure by considering a TA timer.

Claim 1:
A method performed by a User Equipment, UE, for a wireless communication system, the method comprising:
deactivating (S1101) a Secondary Cell Group, SCG;
detecting (S1102) a beam failure of a Primary SCell, PSCell, in the SCG;
initiating (S1103) a SCG failure information procedure upon detecting the beam failure of the PSCell in the SCG while the SCG is deactivated;
skipping (S1104) a Media Access Control, MAC, reset procedure, wherein the MAC reset procedure includes (i) stopping a Time Alignment Timer, TAT, for the SCG and (ii) considering the TAT for the SCG as expired;
transmitting (S1105) SCG failure information message;
determining (S1106) that a random access procedure is not needed for activation of the SCG, based on the TAT being not expired; and
activating the SCG based on the determination.