Terminal, wireless communication method, and base station

Abstract

The present invention provides a wireless communication method, base station, and terminal that ensure proper communication even when cell switching occurs. [Solution] In a next-generation mobile communication system, a user terminal includes a receiving unit that receives a Medium Access Control Element (MAC CE) related to cell switching, and a control unit that controls the triggering of a random access channel (RACH) for a candidate cell based on the information contained in the MAC CE. The MAC CE includes a field for instructing a RACH for the designated candidate cell.

Description

[Technical Field]

[0001] This disclosure relates to terminals, wireless communication methods, and base stations in next-generation mobile communication systems. [Background technology]

[0002] Long Term Evolution (LTE) was specified for Universal Mobile Telecommunications System (UMTS) networks with the aim of achieving even higher data rates and lower latency (Non-Patent Literature 1). Furthermore, LTE-Advanced (3GPP Rel.10-14) was specified for the aim of further increasing capacity and sophistication of LTE (Third Generation Partnership Project (3GPP®) Release (Rel.) 8, 9).

[0003] Successor systems to LTE (for example, 5th generation mobile communication system (5G), 5G+ (plus), 6th generation mobile communication system (6G), New Radio (NR), 3GPP Rel.15 and later, etc.) are also being considered. [Prior art documents] [Non-patent literature]

[0004] [Non-Patent Document 1] 3GPP TS 36.300 V8.12.0 “Evolved Universal Terrestrial Radio Access (E-UTRA) and Evolved Universal Terrestrial Radio Access Network (E-UTRAN); Overall description; Stage 2 (Release 8)”, April 2010 [Overview of the Initiative] [Problems that the invention aims to solve]

[0005] Future wireless communication systems (e.g., wireless communication systems beyond Rel.17 / 5G) are expected to control communication using multiple transmit / receive points (e.g., Multi-TRP (MTRP)) in a serving cell, or to control communication based on inter-cell mobility / intra-cell mobility including non-serving cells.

[0006] During cell switching, it is expected that a random access procedure (e.g., RACH method) will be implemented for candidate cells (or timing advance settings will be configured). However, the question arises as to how the terminal (user terminal, User Equipment (UE)) will control UL transmission to candidate cells (such as the random access procedure and timing advance control mentioned above). If such UL transmission to candidate cells is not properly controlled, the quality of communication during cell switching may deteriorate.

[0007] This disclosure has been made in view of the above, and one of its purposes is to provide a terminal, a wireless communication method, and a base station that can properly perform communication even when cell switching occurs. [Means for solving the problem]

[0008] A terminal according to one aspect of the present disclosure includes a receiving unit that receives a Medium Access Control Element (MAC CE) relating to cell switching, and a control unit that controls the triggering of a random access channel (RACH) to a candidate cell based on the information contained in the MAC CE, wherein the MAC CE includes a field for instructing a RACH to the indicated candidate cell. [Effects of the Invention]

[0009] According to one aspect of the present disclosure, communication can be appropriately performed even when cell switching is performed.

Brief Description of the Drawings

[0010] [Figure 1] FIGS. 1A-1D are diagrams showing an example of multi-TRP. [Figure 2] FIGS. 2A and 2B are diagrams showing an example of inter-cell mobility. [Figure 3] FIGS. 3A and 3B are diagrams showing an example of switching between a serving cell and an additional cell by L1 / L2 signaling. [Figure 4] FIG. 4 is a diagram showing an example of Setting Examples 1-3 when a candidate cell is supported. [Figure 5] FIGS. 5A-5C are diagrams showing an example of a case where switching of a candidate cell / candidate cell group by L1 / L2 signaling is performed in Setting Examples 1-3 when a candidate cell is supported. [Figure 6] FIG. 6 is a diagram showing an example of a timing advance group (TAG) to which a cell included in a cell group belongs. [Figure 7] FIG. 7 is a diagram showing an example of a MAC CE for a timing advance command. [Figure 8] FIGS. 8A and 8B are diagrams showing an example of the timing of PDCCH monitoring. [Figure 9] FIG. 9 is a diagram showing an overview of L1L2-triggered mobility (LTM). [Figure 10] FIG. 10 is a diagram showing RACH (PDCCH ordered RACH) by PDCCH indication having random access response (RAR) monitoring for a serving cell. [Figure 11] FIG. 11 is a diagram showing RACH (PDCCH ordered RACH) by PDCCH indication not having random access response (RAR) monitoring for a candidate cell. [Figure 12] Figure 12 shows an example of the configuration of an existing RAR format (MAC RAR). [Figure 13] Figure 13 shows an example of switching from a serving cell to a candidate cell (target cell). [Figure 14] Figure 14 shows an example of the new RAR format (MAC RAR). [Figure 15] Figure 15 shows another example of the new RAR format (MAC RAR). [Figure 16] Figure 16 shows an example of a schematic configuration of a wireless communication system according to one embodiment. [Figure 17] Figure 17 shows an example of the configuration of a base station according to one embodiment. [Figure 18] Figure 18 shows an example of the configuration of a user terminal according to one embodiment. [Figure 19] Figure 19 shows an example of the hardware configuration of a base station and a user terminal according to one embodiment. [Figure 20] Figure 20 shows an example of a vehicle according to one embodiment. [Modes for carrying out the invention]

[0011] (TCI, spatial relations, QCL) In NR, it is being considered to control the receive processing (e.g., at least one of receive, demapping, demodulation, and decoding) and transmit processing (e.g., transmit, mapping, precoding, modulation, and encoding) of at least one of the signal and channel (referred to as signal / channel) at the UE based on the Transmission Configuration Indication state (TCI state).

[0012] The TCI state may represent the one applied to the downlink signal / channel. The equivalent of the TCI state applied to the uplink signal / channel may be expressed as a spatial relation.

[0013] TCI status refers to information about signal / channel quasi-co-location (QCL), and may also be called spatial reception parameters or spatial relation information. TCI status may be set for each channel or signal in the UE.

[0014] QCL is an index that indicates the statistical properties of a signal / channel. For example, if two signals / channels have a QCL relationship, it may mean that we can assume that at least one of the following is identical between these different signals / channels: Doppler shift, Doppler spread, average delay, delay spread, and spatial parameter (e.g., spatial Rx parameter).

[0015] The spatial reception parameters may correspond to the UE's received beam (e.g., the received analog beam), and the beam may be identified based on the spatial QCL. In this disclosure, QCL (or at least one element of QCL) may be interpreted as sQCL (spatial QCL).

[0016] QCL may have multiple types (QCL types). For example, there may be four QCL types A and D that differ in the parameters (or parameter sets) that can be assumed to be the same, and these parameters (which may also be called QCL parameters) are shown below: • QCL Type A (QCL-A): Doppler shift, Doppler spread, mean delay and delay spread, • QCL Type B (QCL-B): Doppler shift and Doppler spread, • QCL Type C (QCL-C): Doppler shift and mean delay, • QCL Type D (QCL-D): Spatial reception parameters.

[0017] The assumption by the UE that one control resource set (CORESET), channel, or reference signal is in a specific QCL (e.g., QCL type D) relationship with another CORESET, channel, or reference signal may be called a QCL assumption.

[0018] The UE may determine at least one of the transmit beam (Tx beam) and receive beam (Rx beam) of a signal / channel based on the TCI state or QCL assumption of the signal / channel.

[0019] The TCI state may, for example, be information regarding the QCL between the target channel (in other words, the reference signal (RS) for that channel) and another signal (e.g., another RS). The TCI state may be set (indicated) by upper-layer signaling, physical layer signaling, or a combination thereof.

[0020] The channel / signal to which the TCI status applies may also be called the target channel / reference signal (target channel / RS), or simply the target, while the other signal mentioned above may be called the reference signal (reference RS), source RS, or simply the reference.

[0021] The channel on which the TCI state or spatial relationship is set (specified) may be, for example, at least one of the following: Physical Downlink Shared Channel (PDSCH), Physical Downlink Control Channel (PDCCH), Physical Uplink Shared Channel (PUSCH), or Physical Uplink Control Channel (PUCCH).

[0022] Furthermore, the RS that has a QCL relationship with the channel may be at least one of the following: a Synchronization Signal Block (SSB), a Channel State Information Reference Signal (CSI-RS), a Sounding Reference Signal (SRS), a Tracking CSI-RS (also called a Tracking Reference Signal (TRS)), a QCL detection reference signal (also called a QRS), or a Demodulation Reference Signal (DMRS)).

[0023] An SSB is a signal block that includes at least one of a Primary Synchronization Signal (PSS), a Secondary Synchronization Signal (SSS), and a Physical Broadcast Channel (PBCH). An SSB may also be called an SS / PBCH block.

[0024] The RS of a QCL type X in a TCI state may also mean the RS in the relationship between a channel / signal (or its DMRS) and a QCL type X, and this RS may also be called the QCL source of the QCL type X in that TCI state.

[0025] (Initial access procedure) In the initial access procedure, the UE (RRC_IDLE mode) receives the SS / PBCH block (SSB), sends Msg.1 (PRACH / Random Access Preamble / Preamble), receives Msg.2 (PDCCH, PDSCH including Random Access Response (RAR)), sends Msg.3 (PUSCH scheduled by the RAR UL grant), and receives Msg.4 (PDCCH, PDSCH including UE contention resolution identity). Subsequently, when the base station (network) sends an ACK to Msg.4 from the UE, the RRC connection is established (RRC_CONNECTED mode).

[0026] SSB reception includes PSS detection, SSS detection, PBCH-DMRS detection, and PBCH reception. PSS detection involves detecting part of the physical cell ID (PCI), detecting (synchronizing) OFDM symbol timing, and (coarse) frequency synchronization. SSS detection includes detecting the physical cell ID. PBCH-DMRS detection includes detecting part of the SSB index within a half-radio frame (5ms). PBCH reception includes detecting the system frame number (SFN) and radio frame timing (SSB index), receiving configuration information for receiving remaining minimum system information (RMSI, SIB1), and determining whether the UE can camp in that cell (carrier).

[0027] SSB has a bandwidth of 20 RB and a duration of 4 symbols. The transmission period for SSB can be set from {5, 10, 20, 40, 80, 160} ms. Within a half frame, multiple symbol positions for SSB are defined based on the frequency range (FR1, FR2).

[0028] A PBCH has a 56-bit payload. N repetitions of the PBCH are transmitted within an 80ms period. N depends on the SSB transmission period.

[0029] System information consists of MIBs carried by PBCH, RMSI (SIB1), and other system information (OSI). SIB1 contains information for RACH configuration and RACH procedures. The time / frequency resource relationship between SSB and PDCCH monitoring resources for SIB1 is set by PBCH.

[0030] A base station using beam correspondence transmits multiple SSBs using multiple beams during each SSB transmission cycle. Each of the multiple SSBs has multiple SSB indices. When a UE detects one SSB, it transmits a PRACH in the RACH occasion associated with that SSB index and receives a RAR in the RAR window.

[0031] (Multi-TRP) In NR, it is being considered that one or more transmission / reception points (TRPs) (multi-TRPs) will use one or more panels (multi-panels) to perform DL transmissions to the UE. Furthermore, it is being considered that the UE will perform UL transmissions to one or more TRPs.

[0032] Multiple TRPs may correspond to the same cell identifier (Cell Identifier (ID)) or to different cell IDs. This cell ID may be a physical cell ID (e.g., PCI) or a virtual cell ID.

[0033] Figures 1A-1D illustrate examples of multi-TRP scenarios. In these examples, it is assumed, but not limited to, that each TRP can transmit four different beams.

[0034] Figure 1A shows an example of a case where only one TRP (TRP1 in this example) among the multi-TRPs transmits to the UE (this may also be called single-mode or single-TRP). In this case, TRP1 transmits both control signals (PDCCH) and data signals (PDSCH) to the UE.

[0035] In this disclosure, single TRP mode may mean the mode in which multi-TRP(mode) is not set.

[0036] Figure 1B shows an example of a case where only one of the multi-TRPs (TRP1 in this example) transmits control signals to the UE, and that multi-TRP transmits data signals (this may also be called single-master mode). The UE receives each PDSCH transmitted from the multi-TRP based on a single Downlink Control Information (DCI).

[0037] Figure 1C shows an example of a case where each of the multi-TRPs transmits a portion of the control signal to the UE, and the multi-TRP transmits the data signal (this may be called master-slave mode). Part 1 of the control signal (DCI) may be transmitted by TRP1, and part 2 of the control signal (DCI) may be transmitted by TRP2. Part 2 of the control signal may depend on part 1. The UE receives each PDSCH transmitted from the multi-TRP based on these parts of the DCI.

[0038] Figure 1D shows an example of a multi-TRP where each of the multi-TRPs transmits a separate control signal to the UE, and the multi-TRP transmits data signals (this may also be called multi-master mode). TRP1 may transmit a first control signal (DCI), and TRP2 may transmit a second control signal (DCI). The UE receives each PDSCH transmitted from the multi-TRP based on these DCIs.

[0039] When scheduling multiple PDSCHs from a multi-TRP (which may also be called multiple PDSCHs) as shown in Figure 1B using a single DCI, that DCI may be called a single DCI (S-DCI, single PDCCH). Similarly, when scheduling multiple PDSCHs from a multi-TRP (as shown in Figure 1D) using multiple DCIs, these multiple DCIs may be called multiple DCIs (M-DCI, multi-PDCCH (multiple PDCCH)).

[0040] Each TRP in a multi-TRP system may transmit different transport blocks (TBs), code words (CWs), and layers. Alternatively, each TRP in a multi-TRP system may transmit the same TB, CW, and layer.

[0041] Non-Coherent Joint Transmission (NCJT) is being considered as one form of multi-TRP transmission. In NCJT, for example, TRP1 modulates and layers a first codeword and transmits a first PDSCH using a first precode with a first number of layers (e.g., 2 layers). TRP2 modulates and layers a second codeword and transmits a second PDSCH using a second precode with a second number of layers (e.g., 2 layers).

[0042] Furthermore, multiple PDSCHs (Multi-PDSCHs) that are NCJTed may be defined as partially or completely overlapping with respect to at least one of the time and frequency domains. In other words, a first PDSCH from a first TRP and a second PDSCH from a second TRP may overlap in at least one of the time and frequency resources.

[0043] These first and second PDSCHs may be assumed not to be quasi-co-located. Reception of multiple PDSCHs may be reinterpreted as simultaneous reception of PDSCHs that are not of a certain QCL type (e.g., QCL type D).

[0044] In URLLC for multiple TRPs, support for PDSCH (Transport Block (TB) or Codeword (CW)) repetition spanning multiple TRPs is being considered. Support for repetition schemes (URLLC schemes, e.g., schemes 1, 2a, 2b, 3, 4) spanning multiple TRPs on the frequency domain, layer (spatial) domain, or time domain is being considered. In scheme 1, multiple PDSCHs from multiple TRPs are performed using space division multiplexing (SDM). In schemes 2a and 2b, PDSCHs from multiple TRPs are performed using frequency division multiplexing (FDM). In scheme 2a, the redundant version (RV) is the same for multiple TRPs. In scheme 2b, the RV may be the same or different for multiple TRPs. In schemes 3 and 4, multiple PDSCHs from multiple TRPs are performed using time division multiplexing (TDM). In Scheme 3, multi-PDSCH signals from multi-TRPs are transmitted within a single slot. In Scheme 4, multi-PDSCH signals from multi-TRPs are transmitted within different slots.

[0045] Such multi-TRP scenarios allow for more flexible transmission control using high-quality channels.

[0046] NCJT using multiple TRPs / panels may utilize high ranks. To support ideal and non-ideal backhauls between multiple TRPs, both single DCI (single PDCCH, e.g., Figure 1B) and multi-DCI (multi-PDCCH, e.g., Figure 1D) may be supported. For both single and multi-DCI, the maximum number of TRPs may be 2.

[0047] An extension of the TCI is being considered for single PDCCH designs (primarily for ideal backhaul). Each TCI code point within the DCI may correspond to one or two TCI states. The TCI field size may be the same as that of Rel. 15.

[0048] For PDCCH / CORESET as defined in Rel.15, one TCI state without a CORESET Pool Index (CORESETPoolIndex) (also known as TRP Info) is set for one CORESET.

[0049] Regarding the PDCCH / CORESET enhancements specified in Rel.16, in multi-TRP based on multi-DCI, a CORESET pool index is set for each CORESET.

[0050] (Inter-cell mobility) In NR, it is being considered that one or more transmission / reception points (TRPs) (multi-TRPs (MTRPs)) will perform DL transmissions to the UE. It is also being considered that the UE will perform UL transmissions to one or more TRPs.

[0051] In inter-cell mobility (e.g., L1 / L2 inter-cell mobility), the UE may receive channels / signals from multiple cells / TRPs (see Figures 2A and 2B).

[0052] Figure 2A shows an example of inter-cell mobility including non-serving cells (e.g., Single-TRP inter-cell mobility). The UE may configure one TRP (or single TRP) in each cell. Here, the UE receives channels / signals from the base station / TRP of cell #1, which is the serving cell, and from the base station / TRP of cell #3, which is not the serving cell (it becomes a non-serving cell). This corresponds, for example, to the UE switching from cell #1 to cell #3 (e.g., a fast cell switch).

[0053] In this case, the port (e.g., antenna port) / TRP selection may be performed dynamically. The port (e.g., antenna port) / TRP selection may be based on the TCI state indicated or updated by the DCI / MAC CE. Here, we show a case where different physical cell IDs (e.g., PCI) are supported for cell #1 and cell #3.

[0054] Figure 2B shows an example of a multi-TRP scenario (e.g., multi-TRP inter-cell mobility). The UE may have multiple (e.g., two) TRPs (or different CORESET pool indices) configured in each cell. Here, the UE receives channels / signals from TRP#1 and TRP2. Here, TRP#1 corresponds to physical cell ID (PCI)#1 and TRP#2 corresponds to PCI#2.

[0055] Multiple TRPs (TRP#1, #2) may be connected by an ideal / non-ideal backhaul, and information, data, etc., may be exchanged. Each TRP in a multi-TRP may transmit the same or different codewords (CW) and the same or different layers. As one form of multi-TRP transmission, Non-Coherent Joint Transmission (NCJT) may be used, as shown in Figure 2B. Here, we show the case where NCJT is performed between TPRs corresponding to different PCIs. Note that the same serving cell settings may be applied / configured for TRP#1 and TRP#2.

[0056] Multiple PDSCHs (Multi-PDSCHs) that are NCJTed may be defined as partially or completely overlapping with respect to at least one of the time and frequency domains. That is, a first PDSCH from TRP#1 and a second PDSCH from TRP#2 may overlap in at least one of the time and frequency resources. The first and second PDSCHs may be used for transmitting the same TB or for transmitting different TBs.

[0057] These first and second PDSCHs may be assumed not to be quasi-co-located. Reception of multiple PDSCHs may be reinterpreted as simultaneous reception of PDSCHs that are not of a certain QCL type (e.g., QCL type D).

[0058] Multiple PDSCHs from a multi-TRP (which may also be called multiple PDSCHs) may be scheduled using a single DCI (single DCI (S-DCI), single PDCCH) (single master mode). A single DCI may be transmitted from one TRP in the multi-TRP. A configuration using a single DCI in a multi-TRP may be called a single-DCI-based multi-TRP (mTRP / MTRP).

[0059] Multiple PDSCHs from a multi-TRP may be scheduled using multiple DCIs (multi-DCI (M-DCI), multi-PDCCH (multiple PDCCH)) (multi-master mode). Multiple DCIs may be transmitted from each of the multi-TRPs. A configuration that utilizes multiple DCIs in a multi-TRP may be called a multi-DCI-based multi-TRP (mTRP / MTRP).

[0060] A UE may assume that it sends separate CSI reports (CSI reports) for different TRPs, each for each TRP. Such CSI feedback may be called separate feedback, separate CSI feedback, etc. In this disclosure, “separate” may be interpreted as “independent.”

[0061] In inter-cell mobility, either Scenario 1 or Scenario 2 is possible. In this disclosure, "serving cell" may be interpreted as "TRP within a serving cell." Layer 1 / layer 2 (L1 / L2) and DCI / Medium Access Control Control Element (MAC CE) may be interpreted as mutually interchangeable. In this disclosure, a PCI different from the Physical Cell Identity (PCI) of the current serving cell may simply be referred to as "different PCI." Non-serving cells, cells with different PCIs, candidate cells, and additional cells may be interpreted as mutually interchangeable.

[0062] <Scenario 1> Scenario 1 corresponds to, for example, inter-cell mobility in a multi-TRP. However, Scenario 1 may also be a scenario that does not correspond to inter-cell mobility in a multi-TRP. In Scenario 1, for example, the following steps are taken.

[0063] (1) The UE receives from the serving cell the settings for the SSB for beam measurement of the TRP corresponding to a PCI different from that of the serving cell, and the settings necessary to use wireless resources for data transmission and reception, including resources for a different PCI. (2) The UE performs beam measurements of the TRP corresponding to the different PCIs and reports the beam measurement results to the serving cell. (3) Based on the above report, the Transmission Configuration Indication (TCI) status associated with the TRP corresponding to the different PCI is activated by L1 / L2 signaling from the serving cell. (4) UEs send and receive data using dedicated channels on the TRP that correspond to different PCIs. (5) The UE must always cover the serving cell, including in the case of multi-TRP. The UE must use common channels from the serving cell (such as the Broadcast Control Channel (BCCH) and the Paging Channel (PCH)), as in conventional systems.

[0064] In Scenario 1, when the UE sends and receives signals with the additional cell / TRP (the TRP corresponding to the PCI of the additional cell), the serving cell (the UE's assumption of the serving cell) does not change. In other words, L1 / L2 switching of the serving cell is not supported. The UE sets higher-layer parameters related to the PCI of the non-serving cell from the serving cell. Scenario 1 may be applied, for example, in Rel. 17.

[0065] Figure 3A shows an example of UE movement in Rel.17. It assumes that the UE moves from a PCI#1 cell (serving cell) to a PCI#3 cell (additional cell) (overlapping with the serving cell). In this case, Rel.17 does not support L1 / L2 switching of serving cells.

[0066] An additional cell is a cell with an additional PCI that is different from the PCI of the serving cell. UEs can receive / transmit UE-specific channels from the additional cell. UEs need to be within the serving cell's coverage to receive UE-common channels (e.g., system information / paging / short messages). If a UE moves outside the serving cell's coverage, a cell switch is required, such as through a handover (also called L3 mobility).

[0067] <Scenario 2> In Scenario 2, L1 / L2 cell mobility is applied. With L1 / L2 cell mobility, serving cells can be changed using functions such as beam control without RRC reconfiguration. In other words, transmission and reception with additional cells are possible without handover (or without performing the L3 mobility procedure). Since handover requires RRC reconnection and other factors, resulting in a period of no data communication, applying L1 / L2 cell mobility, which does not require handover, allows data communication to continue even when the serving cell is changed. In Scenario 2, for example, the following procedure is performed.

[0068] (1) The UE receives the SSB settings for a cell with a different PCI (additional cell) from the serving cell for beam measurement / serving cell changes. (2) The UE performs beam measurements of the cell using different PCIs and reports the measurement results to the serving cell. (3) The UE may receive the configuration of cells with different PCIs (serving cell configuration) through upper-layer signaling (e.g., RRC). In other words, pre-configuration regarding serving cell changes may be performed. This configuration may be performed together with the configuration in (1) or separately. (4) Based on the above report, the TCI status of cells with different PCIs may be activated by L1 / L2 signaling in accordance with the change in the serving cell. The activation of the TCI status and the change in the serving cell may be performed separately. (5) The UE changes the serving cell (assumed to be the serving cell) and starts receiving / transmitting using the pre-configured individual UE channel and TCI state.

[0069] In other words, in Scenario 2, the serving cell (the assumed serving cell in the UE) is updated by L1 / L2 signaling. Scenario 2 may be applied in Rel. 18 and later.

[0070] Figure 3B shows an example of UE migration in Rel.18. In Rel.18, serving cells are switched via L1 / L2. UEs can receive / transmit UE-dedicated / common channels to and from the new serving cell. UEs may be outside the coverage of the previous serving cell.

[0071] (Setting candidate cells) In L1 / L2 inter-cell mobility, candidate cells may be set in addition to serving cells. In this disclosure, candidate cells may be read as target cells, additional cells, or additional PCIs. One or more candidate cells (or groups of candidate cells) may be associated separately with each serving cell, or one or more candidate cells (or groups of candidate cells) may be commonly associated with multiple serving cells.

[0072] The configuration of candidate cells (or candidate cell groups) may be set using predetermined higher-layer parameters (e.g., ServingCellConfig) in the same way as the inter-cell beam management (inter-cell BM) of existing systems (e.g., Rel.17 and earlier). Alternatively, the configuration of candidate cells (or candidate cell groups) may reuse the framework for carrier aggregation configuration (e.g., CA configuration framework) or the framework for CHO (Conditional Handover) / CPC (Conditional PSCell Change) configuration.

[0073] Candidate cells (or groups of candidate cells) defined by higher-level layer parameters may be activated / deactivated by MAC CE / DCI instructing the UE.

[0074] For setting candidate cells (or associating them with serving cells), at least one of the following setting examples 1 to 3 may be applied. Here, SpCell#0, SCell#1, and SCell#2 are set as serving cells, and an example of candidate cells / candidate cell groups set separately from the serving cells is shown. Setting examples 1 to 3 below are just examples, and the number of serving cells / candidate cells / candidate cell groups, the association between serving cells and candidate cells, etc., are not limited to these and may be changed as appropriate. Alternatively, other setting examples may be supported / applied in addition to / instead of setting examples 1 to 3.

[0075] [Example Configuration 1] Configuration Example 1 shows that one or more candidate cells are associated with / configured for each serving cell (or the frequency domain corresponding to each serving cell) (see Figure 4). Here, candidate cells #0-1, #0-2, and #0-3 are associated with SpCell#0 (or the frequency domain corresponding to SpCell#0), candidate cell #1-1 is associated with SCell#1 (or the frequency domain corresponding to SCell#1), and candidate cells #2-1 and #2-2 are associated with SCell#2 (or the frequency domain corresponding to SpCell#2). Information regarding these associations may be set / instructed by the base station to the UE via RRC / MAC CE / DCI.

[0076] [Example Configuration 2] Configuration Example 2 shows that candidate cells are associated with / configured for MAC entities / MCG / SCG (see Figure 4). This example shows the case where candidate cells #3-#8 are associated with MAC entities / MCG / SCG. In this case, candidate cells are configured for MAC entities or cell groups (e.g., MCG / SCG), rather than being associated with each individual serving cell. Information regarding the candidate cells to be configured for each cell may be configured / instructed by the base station to the UE via RRC / MAC CE / DCI.

[0077] [Example 3] In Configuration Example 3, one or more candidate cell groups are configured (see Figure 4). Each candidate cell group has one or more candidate cells. This example shows the configuration of candidate cell group #1 having candidate cells #0-#2, candidate cell group #2 having candidate cells #0 and #1, and candidate cell group #3 having candidate cell #0. At least one piece of information regarding the configured candidate cell groups and information regarding the candidate cells included in each candidate cell group may be set / instructed by the base station to the UE via RRC / MAC CE / DCI.

[0078] [Switching serving cells] Existing systems (e.g., Rel.17) support L1 beam indication for the TCI status of additional PCIs (or additional cells) (e.g., indication by the TCI status field of the DCI).

[0079] From Rel.18 onward, it is expected that new L1 / L2 signals (e.g., DCI / MAC CE) will be supported to instruct serving cell switching (e.g., serving cell switch). It is also expected that at least one of implicit and explicit instructions will be supported for such instructions. An implicit instruction may mean, for example, that a CORESET is updated to a TCI state associated with an additional PCI by MAC CE. An explicit instruction may mean that the cell switching is directly instructed by DCI / MAC CE.

[0080] For example, in candidate cell setting example 1, a predetermined candidate cell may be designated as a serving cell (or instructed to switch to a serving cell) via L1 / L2 signaling. Figure 5A shows a case where candidate cells #0-2 become MCG / SCG SpCells via L1 / L2 signaling (SpCell #0 and candidate cells #0-2 are switched). It also shows a case where candidate cell #2-1 becomes MCG / SCG SCell (SCell #2 and candidate cell #2-1 are switched) via L1 / L2 signaling.

[0081] Alternatively, in candidate cell setting example 2, a predetermined candidate cell may be designated as a serving cell (or instructed to switch to a serving cell) via L1 / L2 signaling. Figure 5B shows a case where candidate cell #4 becomes an MCG / SCG SpCell (SpCell #0 and candidate cell #4 are switched) via L1 / L2 signaling.

[0082] Alternatively, in candidate cell setting example 3, a predetermined candidate cell group (or one or more candidate cells included in the predetermined candidate cell group) may be changed / updated to a serving cell group via L1 / L2 signaling. Figure 5C shows a case where candidate cell group #1 (or candidate cells #0-#2 included in candidate cell group #1) becomes a serving cell group (the serving cell group and candidate cell group #1 are switched) via L1 / L2 signaling. Among the candidate cells included in candidate cell group #1 (here, candidate cells #0-#2), a candidate cell associated with SpCell #0 or a candidate cell set in the same frequency domain as SpCell #0 (here, candidate cell #0) may be set as a new SpCell. Alternatively, the candidate cell that becomes an SpCell may be indicated by L1 / L2 signaling.

[0083] (Timing Advance Group) When using multiple TRPs, the distance between the UE and each TRP may differ. Multiple TRPs may be contained within the same cell (e.g., a serving cell). Alternatively, some TRPs may correspond to a serving cell, while others correspond to non-serving cells. In this case, it is conceivable that the distance between each TRP and the UE will differ.

[0084] In existing systems, the transmission timing of UL (Uplink) channels and / or UL signals (UL channels / signals) is adjusted by Timing Advance (TA). The reception timing of UL channels / signals from different user terminals (UEs) is adjusted at the base station (TRP: Transmission and Reception Point, also known as gNB: gNodeB, etc.).

[0085] The UE may control the timing of UL transmission by applying a timing advance (multiple timing advance) for each pre-configured Timing Advance Group (TAG).

[0086] When applying multiple timing advances, Timing Advance Groups (TAGs) are supported, categorized by transmission timing. The UE may control the UL transmission timing for each TAG, assuming that the same TA offset (or TA value) is applied to each TAG. In other words, the TA offset may be set independently for each TAG.

[0087] When applying Multiple Timing Advance, the UE can independently adjust the transmission timing of the cells belonging to each TAG, allowing the radio base station to synchronize the uplink signal reception timing from the UE, even when using multiple cells.

[0088] TAGs (for example, serving cells belonging to the same TAG) may be defined by higher-level parameters. The same timing advance value may be applied to serving cells belonging to the same TAG. The timing advance group containing a MAC entity's SpCell may be called the primary timing advance group (PTAG), and the other TAGs may be called secondary timing advance groups (STAG).

[0089] In existing systems (e.g., Rel.16 NR), the setting of up to four TAGs is supported per cell group (e.g., MCG / SCG) (see Figure 6). Figure 6 shows a case where three TAGs are set for a cell group containing SpCell and SCell#1~#4. Here, SpCell and SCell#1 belong to the first TAG (PTAG or TAG#0), SCell#2 and SCell#3 belong to the second TAG (TAG#1), and SCell#4 belong to the third TAG (TAG#2).

[0090] A timing advance command (TA command) may be communicated to the UE using a MAC control element (e.g., MAC CE). The TA command is a command indicating the transmission timing value for the uplink channel and is included in the MAC control element. The TA command is signaled to the UE from the radio base station at the MAC layer. The UE controls a predetermined timer (e.g., a TA timer) based on the reception of the TA command.

[0091] A MAC CE for timing advance commands (TAC MAC CE) may be configured to include a field for the timing advance group index (e.g., TAG ID) and a field for the timing advance command (see Figure 7).

[0092] On the other hand, future wireless communication systems are expected to have cases where one or more TRPs corresponding to a given cell (or CC) are assigned different TAGs (or TAG-IDs). For example, in multi-TRP operations using multi-DCI, it is expected that two TAs (or TAGs) will be supported for UL transmission.

[0093] Alternatively, different TRPs corresponding to a given cell may share a common TAG. Furthermore, a MAC CE for TA commands may apply to only one TRP, or to multiple TRPs.

[0094] Alternatively, different TRPs (Traffic Rate Programs) may use different TAGs for different cells, or they may share a common TAG. For example, in intercell mobility, it is conceivable that UL transmissions could be controlled based on common / different timing advances for serving cells (or serving cell TRPs) and non-serving cells (or non-serving cell TRPs).

[0095] Thus, MIMO versions Rel.18 and later are expected to support two timing advances (TAs) for two TRPs in multi-TRP operation using multi-DCI.

[0096] If TAGs are set / controlled on a TRP basis, a time alignment timer (e.g., timeAlignmentTimer) may be set for each TRP. The time alignment timer may control the time at which a MAC entity considers a serving cell belonging to an associated TAG to be uplink time aligned. For example, a time alignment timer may be set by the RRC to maintain UL time alignment.

[0097] A time alignment timer (e.g., timeAlignmentTimer) may be maintained for UL time alignment. In Rel.17, a time alignment timer (e.g., timeAlignmentTimer) corresponds to each TAG. When the UE receives a MAC CE for a timing advance command (e.g., TAC MAC CE), it starts or restarts the time alignment timer associated with the indicated timing advance group (e.g., TAG).

[0098] The MAC entity receives the TAC MAC CE and a predetermined value (N) between it and the indicated TAG. TA If the specified value (N) is maintained, apply the timing advance command to the specified TAG, or start or restart the time alignment timer associated with the specified TAG. TA ) may also be a timing advance between DL and UL.

[0099] The behavior when the time alignment timer expires may be defined separately for PTAG and STAG. Furthermore, the timing advance group (TAG) containing the MAC entity's SpCell may be called the primary timing advance group (PTAG), and the other TAGs may be called secondary timing advance groups (STAG).

[0100] For example, in Rel.17, it is supported that when the timing advance timer corresponding to PTAG expires, a predetermined operation for PTAG is applied, and when the timing advance timer corresponding to STAG expires, a predetermined operation for STAG is applied.

[0101] For example, if the time alignment timer expires, the following actions (e.g., a predetermined PTAG action / a predetermined STAG action) may be performed.

[0102] [Operation for specified PTAGs] If the time alignment timer is associated with the PTAG, • Flushes (discards) all HARQ buffers in all serving cells. • If configured, notify RRC to release PUCCH for all serving cells. • If configured, notify RRC to release the SRS. • Clear all configured DL (Download) and UL (Ultimate Load) allocations. Clear the PUSCH resources for semi-persistent CSI reporting. • Complete all time alignment timers during your run. • All TAGs N TA Maintain.

[0103] [Operation for specified STAG] If a time alignment timer is associated with a STAG, then for all serving cells belonging to that TAG, • Flushes (discards) all HARQ buffers. • If configured, notify RRC to release PUCCH. • If configured, notify RRC to release the SRS. • Clear all configured DL and UL assignments. Clear the PUSCH resources for semi-persistent CSI reporting. • N of the TAG TA Maintain.

[0104] If candidate cells are set / defined, it may be supported to control communication by taking into account the corresponding timing advance (TA) for each candidate cell. For example, as described above, each candidate cell may be associated with a TAG.

[0105] Furthermore, if candidate cells are configured / applied / supported, it is expected that different serving cells / different candidate cells may be associated with the same TAG. The candidate cell's TAG may be instructed by the base station or determined by the UE based on the candidate cell's TAG obtained.

[0106] It is also conceivable that the UE might consider the TA (Time Agent) corresponding to a candidate cell when sending a UL (Urgent Request) for a candidate cell (for example, a candidate cell that has been instructed to switch to a serving cell). If the TA of a candidate cell is considered, the UE will need to acquire the TA of the candidate cell (for example, TA acquisition of candidate cells).

[0107] Several methods for obtaining TA (Technical Analysis) of candidate cells are possible, including TA acquisition using RACH (e.g., RACH-based solutions) and TA acquisition without using RACH (RACH-less solutions). The TA acquisition method may also be interpreted as a TA acquisition scheme, TA acquisition type, or TA acquisition procedure. In this disclosure, TA acquisition, TA measurement, TA calculation, TA determination, and TA determination may be interpreted interchangeably.

[0108] For example, a UE may obtain the TA of a candidate cell by sending a RACH (e.g., PDCCH order RACH) instructed / triggered by a PDCCH to the candidate cell. Information about the candidate cell's TA (e.g., TA value) may be included in the RACH response signal (e.g., RAR). The RAR may be sent from the serving cell or from the candidate cell. Alternatively, the candidate cell's TA may be obtained using a RACH triggered by the UE or a RACH triggered at a higher layer in the network. The PDCCH order may be triggered by the source cell (or serving cell) alone.

[0109] Alternatively, the UE may obtain the candidate cell's TA by transmitting a signal other than RACH to the candidate cell. Information regarding the candidate cell's TA (e.g., TA value) may be provided to the UE by the base station. As a signal other than RACH, for example, SRS may be applied.

[0110] Alternatively, the UE may measure / calculate / acquire the TA for a candidate cell based on the DL signal (e.g., downlink reference signal) transmitted from each cell (e.g., candidate cell / serving cell). The method by which the UE acquires the TA for a candidate cell based on DL signals transmitted from one or more cells may be called UE-based TA measurement.

[0111] In UE-based TA measurement, the downlink reference signal may be a predetermined DL signal (e.g., a synchronization signal block (e.g., SSB) / CSI-RS, etc.). For example, the UE may measure the difference in reception timing of DL signals from multiple cells (or two cells) and obtain the TA of a candidate cell.

[0112] Multiple cells may include a reference cell (e.g., a serving cell). In this case, the UE may calculate the required TA for the candidate cell based on the reception timing of the reference cell (and the TA value of the reference cell) and the timing difference (e.g., T) between the reference cell and the candidate cell. The UE may also obtain the TA of the candidate cell using a timing advance command (TAC) sent from the serving cell.

[0113] (TA control per TRP / panel) As mentioned above, when using multiple transmission / reception points (e.g., TRPs) / panels for communication, it is also conceivable that timing advance (TA) may be controlled for each TRP / panel.

[0114] In NRs Rel.18 and later, for RACH triggered by PDCCH orders and RACH triggered by UEs, it is conceivable that contention-based random access (CBRA) and contention-free random access (CFRA) will be considered / determined on a TRP basis or a TRP TA (TA per TRP) basis.

[0115] If timing advances can be applied / configured for each TRP (or on a per-TRP basis), the UE controls UL transmissions (e.g., RACH transmissions, etc.) in each TRP based on the timing advance corresponding to each TRP (or the timing advance group to which each TRP belongs).

[0116] Information regarding the TRP corresponding to each serving cell (e.g., TRP index / TRP ID) may be set / instructed to the UE by the base station using RRC / MAC CE / downlink control information. The UE may also receive relevant information regarding the timing advance corresponding to each TRP (e.g., information regarding TA value / timing advance command / time alignment timer, etc.) from the base station.

[0117] Each embodiment of this disclosure may be applied to / supported in at least one of intra-cell multi-TRPs and inter-cell multi-TRPs.

[0118] In a multi-TRP within a cell, multiple TRPs (or the activated TCI states of multiple TRPs) may be associated with the same cell ID. The cell ID may be the physical cell ID (PCI).

[0119] In inter-cell multi-TRP, multiple TRPs (or the activated TCI states of multiple TRPs) may be associated with different cell IDs (e.g., PCIs). For example, in inter-cell multi-TRP, two TRPs may be interpreted as two TRPs each associated with two PCIs.

[0120] If the application / setting of timing advance is supported for each TRP (or per TRP), each TRP may belong to a different TAG. Multiple TRPs in a serving cell (e.g., two TRPs) may each belong to two TAGs. A TAG may contain multiple TRPs from multiple serving cells. All TRPs / serving cells within a TAG apply / maintain the same timing advance (TA) / same time alignment timer.

[0121] In this disclosure, a TAG may contain one or more sub-TAGs. For example, two TRPs of a serving cell may each belong to two sub-TAGs and also to one TAG. A sub-TAG may contain multiple TRPs from multiple serving cells. All TRPs / serving cells within a sub-TAG apply / maintain the same timing advance (TA) / same time alignment timer.

[0122] For example, a TA may be applied to each TRP (or instructions may be given on a TRP TA basis). For example, at least one of the following options may be applied.

[0123] [Option 1] A different TAG-ID may be set for each TRP, and a different MAC CE for TA commands may be set for each TRP. Each TAG may maintain a time alignment timer for UL time alignment.

[0124] [Option 2] Different TRPs may share a TAG. A MAC CE for a TA command may be applied to only one TRP. The UE applies different TAs to other TRPs. For example, the UE may adjust the TA value for other TRPs (e.g., TRP#1) by a TA offset (TA_TRP_offset) based on the TA for TRP#0 (TA_TRP#0).

[0125] In this case, only one time alignment timer may exist for the UL time alignment of multiple TRPs. This may mean that the UL time alignment of multiple TRPs may be maintained or lost simultaneously.

[0126] [Option 3] There may be only one TAG. The MAC CE for the TA command may be applied to multiple serving TRPs for the UE.

[0127] [Option 4] There may be only one TAG. MAC CEs for TA commands received on a TRP / CW / PDSCH / DMRS port group may be applied to the same TRP / CW / PDSCH / DMRS port group of the TAG. Each TRP / CW / PDSCH / DMRS port group of the TAG maintains a time alignment timer for UL time alignment.

[0128] Thus, in Rel.18 and later, it is anticipated that multiple timing advances will be supported in multi-TRP (e.g., multi-TRP using multi-DCI). For example, multiple (e.g., two) timing advances may be supported for multi-TRP using multi-DCI (e.g., two TRPs). Furthermore, the application of multiple timing advances to multi-TRP may be supported in intra-cell / inter-cell multi-DCI multi-TRP scenarios, or in multiple frequency ranges (e.g., FR1 and FR2).

[0129] (PDCCH order) DCI format 1_0 includes a DCI format identifier field, a bit field that is always set to 1, and a frequency domain resource assignment field. If the cyclic redundancy check (CRC) of DCI format 1_0 is scrambled by C-RNTI and the frequency domain resource assignment field is all 1, then that DCI format 1_0 is for a random access procedure initiated by a PDCCH order, and the remaining fields are the random access preamble, UL / supplementary Uplink (SUL) indicator, SS / PBCH index (SSB index), PRACH mask index, and reserved bits (12 bits).

[0130] For PRACH transmissions triggered by a PDCCH order, the PRACH mask index field indicates the PRACH occasion of the PRACH transmission associated with the SS / PBCH block index indicated by the SS / PBCH block index field of the PDCCH order, provided the value of the random access preamble index field is non-zero.

[0131] (RACH procedure triggered by PDCCH order) In existing systems (e.g., Rel.17 and earlier), for a RACH procedure for a specific cell (e.g., SpCell), the UE performs the RACH procedure assuming that the PDCCH order and the PDCCH for RAR have the same QCL characteristics. The PDCCH for RAR may be a PDCCH transmitted by the base station in response to a PRACH triggered to (or transmitted by) the UE by the PDCCH order. The PDSCH scheduled by the RAR PDCCH may include RAR. The QCL characteristics may be interpreted as DMRS QCL characteristics.

[0132] Specifically, if a UE detects DCI format 1_0 scrambled with CRC by the corresponding RA-RNTI in response to a PRACH transmission initiated by a PDCCH order that triggers a CFRA procedure for a SpCell, the UE may assume that the PDCCH containing DCI format 1_0 and the PDCCH order have the same DMRS antenna port pseudo-collocation characteristics.

[0133] In addition, in RAR monitoring that is not triggered by a PDCCH order, the QCL of the CORESET that transmits the RAR may be the same as the SSB / CSI-RS used for PRACH.

[0134] Furthermore, in existing systems (e.g., Rel.17 and earlier), there are no restrictions on RACH procedures for other cells (e.g., SCell) as there are for specific cells, and the UE is supported to use the QCL of a given CORESET for receiving PDCCH for RAR. The given CORESET may be a CORESET associated with a type 1 CSS set (e.g., type 1-PDCCH CSS set).

[0135] Specifically, if a UE performs detection of DCI format 1_0 scrambled with CRC by the corresponding RA-RNTI in response to a PRACH transmission initiated by a PDDCCH order that triggers a CFRA procedure for a SCell, the UE may assume a pseudo-collocation characteristic of the DMRS antenna port of the CORESET associated with a type 1-PDCCH CSS set for receiving PDCCHs containing DCI format 1_0.

[0136] Thus, in RAR monitoring for RACH of the PDCCH order for SCell, the QCL of the CORESET for RAR may be associated with the type 1-PDCCH CSS set.

[0137] By the way, in order to obtain TA for each TRP (or TA for serving and non-serving cells), a RACH may be triggered for each TRP (or for each serving / non-serving cell). For PDCCH orders that trigger a RACH procedure to a TRP (or serving / non-serving cell), there may be cases where the PDCCH order and the PDCCH for RAR are sent from different TRPs. In such cases, it is necessary to relax / change the restriction that the PDCCH order and the PDCCH for RAR must have the same DMRS QCL characteristics.

[0138] For example, it may be supported that a PDCCH order from TRP#1 triggers a RACH to TRP#2, and a RAR is sent from TRP#2. In this case, it becomes possible to trigger a RACH to any TRP via a PDCCH order from any TRP, increasing the flexibility of the RACH procedure.

[0139] As another example, it may be supported that a PDCCH order from TRP#2 triggers a RACH to TRP#2, and a RAR is sent from TRP#1. This example may occur in inter-cell multi-TRP (e.g., inter-cell M-TRP) cases when the UE is unable to receive a type 1CSS set from a non-serving cell's TRP.

[0140] Furthermore, in the RACH procedure triggered by the PDCCH order described above, the UE may be configured / instructed to receive RAR.

[0141] For example, if RAR reception is not configured / instructed, the timing advance (value) of the candidate cell may be instructed by the cell switching command.

[0142] The following are also being considered: If RAR reception is not configured / instructed, is it acceptable for the UE not to resend PRACH? How does the UE determine the transmit power of a subsequent PRACH triggered by a PDCCH order? If RAR reception is not configured / instructed, the UE does not know whether the RAR was received from the serving cell or the target cell (candidate cell). • If RAR reception from the target cell is configured for the UE, check whether the target cell's type 1-PDCCH CSS(set) is configured for the UE. • Specific details of RAR. • Signaling to configure / instruct whether or not RAR should be received. • Introduction of UE capabilities to support RAR inclusion / exclusion.

[0143] The UL's TA is expected to be obtained before receiving a cell switch command. If the TA is already indicated to the UE before receiving the cell switch command (for example, by the RAR (for PDCCH order RACH) mentioned above), then the TA does not need to be indicated by the MAC CE for the cell switch command. On the other hand, if the UE is configured not to require RAR, then the TA needs to be indicated by the MAC CE for the cell switch command.

[0144] (Random access procedure in MAC entities) Random access procedures are initiated by a PDCCH order, the MAC entity itself, or an RRC for a specification-compliant event. Within a MAC entity, there is only one random access procedure in progress at any given time. Random access procedures for SCells are initiated only by a PDCCH order with a ra-PreambleIndex different from 0b000000.

[0145] When a random access procedure is initiated on a serving cell, the MAC entity performs the following actions: If a random access procedure is initiated by a PDCCH order and the ra-PreambleIndex explicitly provided by the PDCCH is not 0b000000, or if a random access procedure is initiated for a reconfiguration with synchronization and a contention-free random access resource of type 4-step RA is explicitly provided by rach-ConfigDedicated for the BWP selected for the random access procedure, set RA_TYPE to 4-stepRA.

[0146] If the selected RA_TYPE is set to 4-stepRA, the MAC entity does the following: If ra-PreambleIndex is explicitly provided by PDCCH and ra-PreambleIndex is not 0b000000, set PREAMBLE_INDEX to the notified ra-PreambleIndex and select the SSB notified by PDCCH. • If an SSB is selected as described above, the MAC entity determines the next available PRACH occasion from the PRACH occasions corresponding to the selected SSB, permitted by the limitations given by ra-ssb-OccasionMaskIndex (the MAC entity randomly selects a PRACH occasion with equal probability from consecutive PRACH occasions corresponding to the selected SSB, in accordance with the specification. When determining the next available PRACH occasion corresponding to the selected SSB, the MAC entity may consider the possibility of a measurement gap occurring).

[0147] For example, if a new random access procedure is started while another random access procedure is already in progress within a MAC entity, it is up to the UE implementation to decide whether to continue the ongoing procedure or start the new procedure (such as an SI request).

[0148] If a UE receives another PDCCH order that exhibits the same random access preamble, PRACH mask index, and UL carrier, and there is an ongoing random access procedure triggered by that PDCCH order, that procedure will be considered the same random access procedure as the ongoing one and will not be reinitialized.

[0149] (SCell activation / deactivation) If one or more SCells are configured on a MAC entity, the network (NW) can activate / deactivate the configured SCells. After a SCell is configured, it remains deactivated unless a parameter (sCellState) is set to activate for the SCell by a higher layer.

[0150] One or more configured SCells may be activated / deactivated based on at least one of the following conditions: • Receives SCell Activation / Deactivation MAC CE. • Receives extended SCell Activation / Deactivation MAC CE. • Set a timer (sCellDeactivationTimer) for each SCell (excluding SCells with PUCCH enabled). When the timer expires, the associated SCell will be deactivated. • Set sCellState for each configured SCell. In this case, the associated SCell will be activated based on the SCell's settings.

[0151] If SCell is not activated, the UE may perform / expect the following actions: • Do not send SCell SRS. • Do not report SCell CSIs. • Do not send UL-SCH in SCell. • Do not send RACH in SCell. • Do not monitor PDCCH in SCell. Do not monitor PDCCH for SCell. • Do not send PUCCH in SCell.

[0152] HARQ feedback for MAC Protocol Data Units (PDUs), including SCell Activation / Deactivation MAC CEs or Enhanced SCell Activation / Deactivation MAC CEs, is unaffected by PCell / PSCell / PUCCH-SCell interruptions resulting from Scell ​​activation / deactivation. On the other hand, if an SCell is deactivated, any ongoing random access procedures in the SCell will be interrupted.

[0153] (Time between PDCCH order reception and PRACH transmission <timeline>) If a random access procedure is initiated by a PDCCH order, the UE will, if requested by a higher layer, transmit a PRACH within a selected PRACH occasion, provided that the time between the last symbol of the PDCCH order reception and the first symbol of the PRACH transmission is greater than or equal to N_(T,2)+Δ_BWPSwitching+Δ_Delay+T_switch[msec] (time condition), as described in the specification, where N_(T,2) is the duration of N_2 symbols corresponding to the PUSCH preparation time for UE processing capability 1. μ corresponds to the SCS setting for PRACH transmission. For example, assume that μ corresponds to the minimum SCS setting between the subcarrier spacing (SCS) setting of the PDCCH order and the corresponding SCS setting for PRACH transmission. If the active UL BWP does not change, Δ_BWPSwitching=0; otherwise, Δ_BWPSwitching is defined in the specification. Δ_delay = 0.5 msec in FR1 and Δ_delay = 0.25 msec in FR2. T_switch is the switching gap duration defined in the specification.

[0154] UE is determined by CellSpecific_Koffset K cell,offset If provided, the PRACH occasion is slot n+2 μ ·K cell,offset This follows. Here, n is T TA This is the UL BWP slot for a PRACH transmission that coincides with the end of a PDCCH order reception, assuming μ = 0. μ corresponds to the SCS setting for the PRACH transmission. If a PDCCH reception for a PDCCH order includes two PDCCH candidates from two linked searchspace sets based on searchSpaceLinkingId, the final symbol of the PDCCH reception is the final symbol of the later terminating PDCCH candidate. A PDCCH reception includes two PDCCH candidates even if the UE does not need to monitor either of the two PDCCH candidates.

[0155] If a UE responds to a PRACH transmission initiated by a PDCCH order that triggers a CFRA procedure for a SpCell and attempts to detect a DCI format 1_0 having a CRC scrambled by the corresponding RA-RNTI, the UE may assume that the PDCCH containing the DCI format 1_0 and the PDCCH order have the same DM-RS antenna port QCL characteristics.

[0156] If a UE attempts to detect a DCI format 1_0 with a CRC scrambled by the corresponding RA-RNTI in response to a PRACH transmission initiated by a PDDCCH order that triggers a CFRA procedure for a SCell, the UE may assume a DMRS antenna port QCL characteristic of the CORESET associated with a type 1-PDCCH CSS set configured for receiving PDCCHs containing DCI format 1_0.

[0157] Thus, the timing of PRACH occasions is related to μ and CellSpecific_Koffset.

[0158] (RACH procedure for non-serving cells for L1 / L2 centric inter-cell mobility) When RRC configures one or more non-serving cell information for UE, it may include RACH settings for the non-serving cell(s). Options 1-3 below illustrate cases where RACH is supported for candidate cells triggered by a PDCCH order.

[0159] <Option 1> The UE may determine the cell to which a PDCCH order (or a PRACH transmitted by a PDCCH order) corresponds based on predetermined parameters used in the PDCCH of the PDCCH order. The predetermined parameters may be, for example, the TCI status.

[0160] For example, if a base station sends a PDCCH order for PRACH and PDCCH (or DCI / CORESET) is associated with a TCI state from a non-serving cell, the PRACH requested by the PDCCH order may correspond to a non-serving cell. In this case, the UE may control the PRACH transmission based on the non-serving cell's PRACH setting. The UE may then determine the TA of the non-serving cell based on the DL transmission (e.g., RAR) that is fed back to the PRACH transmission.

[0161] If PDCCH (or DCI / CORESET) is associated with the TCI state from the serving cell, the PRACH requested by the PDCCH order may correspond to the serving cell. In this case, the UE may control the transmission of the PRACH based on the serving cell's PRACH setting. The UE may then determine the TA of the serving cell based on the DL transmission (e.g., RAR) that is fed back to the PRACH transmission.

[0162] <Option 2> The UE may determine the cell to which the PDCCH order (or the PRACH transmitted by the PDCCH order) corresponds based on the DCI (or CORESET) used for the PDCCH order.

[0163] For example, the DCI used in a PDCCH order may include identification information for the corresponding cell (e.g., cell index / cell type (e.g., serving cell / non-serving cell)) and notify the UE of this information. In a predetermined DCI format used in a PDCCH order (e.g., DCI format 1_0), X reserved bits of the DCI may be used to notify the cell in order for PRACH to explicitly indicate the corresponding serving cell / non-serving cell. These reserved bits may be those included in DCI format 1_0 in an existing system (e.g., Rel. 15 / 16).

[0164] The bit size of X may be set / determined / decided based on the number of non-serving cells set. For example, if one non-serving cell is set, X may be 1 bit. In this case, '0' may indicate a serving cell and '1' may indicate a non-serving cell. The field used to notify the cell identification information may be the most significant bit (MSB) or least significant bit (LSB) of the reserved bit.

[0165] Furthermore, if three non-serving cells are configured, X may be 2 bits. To indicate a non-serving cell, the re-indexed index of the non-serving cell may be applied. The association between the cell index and the bit value (or code point) may be defined in the specification or established by higher-layer signaling, etc. For example, the code point '0' or '00' may indicate a serving cell, and the remaining bits may be associated with the index order of the configured non-serving cells (e.g., ascending / descending).

[0166] Alternatively, the size of X may be fixed, and the number of bits may not change regardless of the number of non-serving cells set. In this case, unused bits / fields may be configured as reserved bits.

[0167] <Option 3> If the random access preamble index (e.g., ra-PreambleIndex) is within a predetermined range (e.g., 0-63), a portion of the preamble may be configured / activated by the RRC / MAC CE to relate to non-serving cells.

[0168] In this case, information about serving / non-serving cells may be indicated by a predetermined field in a predetermined DCI format (e.g., DCI format 1_0). The predetermined field may be, for example, a random access preamble index field. The preamble settings associated with non-serving cells may be configured to apply only to PRACH transmissions based on the PDCCH order (or not to collision-type PRACH transmissions).

[0169] If DCI specifies a preamble associated with a non-serving cell, the UE may control the PRACH transmission to have the specified preamble, according to the RACH settings of the non-serving cell.

[0170] The UE may adjust the TA of one or more indicated cells after a PRACH based on the PDCCH order. Information regarding the TA may be received by a response signal to the PRACH transmission (e.g., RAR).

[0171] (RACH procedure for each TRP in a multi-TRP environment) By the way, in the multi-TRP scenario described above, there has been insufficient consideration given to how to perform the RACH procedure for each TRP (or TRP TA).

[0172] For example, in a RACH procedure for a candidate cell triggered by a PDCCH order, it is unclear from which cell the candidate cell's PDCCH order is sent. Candidate cells are not limited to SpCell / PCell; SCells can also be candidate cells.

[0173] For example, it is unclear how to send PDCCH orders for inactive cells / candidate deactive cells. Note that in existing systems, the UE does not perform PDCCH monitoring for deactive cells.

[0174] Furthermore, if PDCCH orders are sent in each cell, the UE needs to monitor the PDCCH (at least the PDCCH orders) of multiple candidate cells. Moreover, the UE may not know which candidate cells' PDCCH orders it should monitor.

[0175] A network can send two PDCCH orders to two cells for PRACH, but since the preamble / mask (PRACH mask index) / UL carrier instructions are the same (common), existing rules are not appropriate (not applicable). For example, if a UE has an ongoing random access procedure triggered by one PDCCH order, and receives another PDCCH order indicating the same random access preamble / PRACH mask index / UL carrier, that procedure will be considered the same random access procedure as the one in progress and will not be reinitialized.

[0176] <Option 1> A PDCCH order sent to the UE in a cell #A may trigger a PRACH in that cell #A. For example, if the NW wants to trigger a RACH in candidate cell #A, the NW needs to send a PDCCH order in candidate cell #A.

[0177] In this disclosure, cells #A and #B are candidate cells and may be SpCell / PCell / SCell unless otherwise specified.

[0178] [Option 1-1] The network may support sending PDCCH orders, PDCCH monitoring, and PRACH transmissions for inactive (deactive) cells / deactive candidate cells. In this case, the network does not need to provide the candidate cell ID to the UE to trigger RACH.

[0179] [Options 1-2] The UE may determine which PDCCH cells need to be monitored / should be monitored based on at least one of the following options:

[0180] [Option 1-2-1] The network may define the candidate cells / TAGs / reference CCs / candidate cells per TAG that the UE needs to monitor for PDCCH (including at least PDCCH order / DCI format 1_0) by RRC / MAC CE. The UE may determine the candidate cells / TAGs / reference CCs / candidate cells per TAG that need to be monitored based on the RRC / MAC CE. Candidate cells may include deactive SCells.

[0181] For candidate cells (including deactive SCells) / TAGs / reference CCs per TAG shown in the network, the UE may monitor the PDCCH order. For other candidate cells, the UE does not need to monitor the PDCCH order. Here, reference CCs per TAG may mean that the network / UE only needs to obtain a TA based on this reference CC for all cells within the TAG.

[0182] [Option 1-2-2] A PDCCH order sent to the UE in a cell #A may trigger a PRACH in a different cell #B (details will be described later in the second embodiment).

[0183] [Options 1-2-3] The UE may determine candidate cells to be monitored via PDCCH based on certain (predetermined) rules. These rules may be at least one of the following: • Candidate cells for which L1 beam measurement / reporting has been set. • Candidate cells with active TCI status / TRS / CSI measurement / reporting configured. • The candidate cell (per TAG) with the smallest cell ID among the candidate cells listed above. In this case, the UE only needs to determine one candidate cell for each TAG that should be monitored via PDCCH.

[0184] [Variations] In options 1-1 and 1-2, the UE monitors a specific DCI format (e.g., DCI format 1_0 with CRC scrambled by the corresponding RA-RNTI / C-RNTI) in candidate cells (deactive cells / configured cells). This reduces the number of BDs and thus the UE load. However, it is not limited to this. For example, the UE may monitor any DCI format scrambled by any RNTI.

[0185] Figures 8A and 8B show examples of PDCCH monitoring timings related to Option 1. The UE may receive the PDCCH order transmitted in cell #A at the timing shown in either Figure 8A or Figure 8B.

[0186] For example, as shown in Figure 8A, the UE may receive a PDCCH order at any time. In this case, the UE must always monitor the PDCCH, even if the SCell is deactivated.

[0187] Furthermore, as shown in Figure 8B, the UE may receive a PDCCH order at a specific time. In this case, the UE only needs to monitor the PDCCH for a specific time duration. The monitoring / non-monitoring periods may be predetermined by specification or set / instructed by RRC / MAC CE / DCI. The specific duration may be the same as the DRX duration, a portion of the DRX duration, or a period including the DRX duration.

[0188] According to Option 1, the UE can appropriately determine in the RACH procedure which cell the candidate cell's PDCCH order will be sent from.

[0189] <Option 2> Option 2 concerns the case where a PDCCH order sent to the UE in cell #A triggers a PRACH in a different cell #B. Cells #A and #B may belong to the same MCG / SCG or to the same TAG.

[0190] [Option 2-0] In this option, the UE may trigger RACH based on at least one of the following options:

[0191] [Option 2-0-1] Any active serving cell (cell #A) may trigger RACH on a candidate cell (cell #B (which may be any other serving cell)).

[0192] [Option 2-0-2] Only cell #A, which is an SPCell, may trigger RACH on the candidate cell (cell #B).

[0193] [Option 2-0-3] Only an activated scheduling cell (cell #A) may trigger RACH on the scheduled cell (cell #B) associated with cell #A. The association between cells #A and #B (e.g., based on cross-carrier scheduling) may be set / instructed by RRC.

[0194] A maximum number of scheduling cells may be defined for a scheduling cell (cell #A).

[0195] Assuming that a scheduled cell ID is indicated by a new carrier indicator field (CIF) within a PDCCH order, the CIF value used for a single scheduled cell (cell #B) within the PDCCH order may be explicitly set via RRC, while the multiple CIF values ​​used for multiple scheduled cells within the PDCCH order may be implicitly determined based on the order of the cell indexes / PCIs of those multiple scheduled cells. In the implicit case, for example, a smaller cell index / PCI may map to a smaller CIF value.

[0196] [Option 2-0-4] Cell #A (the cell that can trigger RACH for each TAG) may be explicitly or implicitly set by the RRC / MAC CE, or it may be predefined in the specification. For example, the cell with the smallest cell ID for each TAG / CG (cell group), or the active cell with the smallest cell ID for each TAG / CG (cell group), may be cell #A (the cell that can trigger RACH).

[0197] According to Option 2-0, the UE does not need to monitor PDCCH orders in deactive cells / many cells. In this case, PRACH transmission in deactive cells / candidate deactive cells may be supported.

[0198] To indicate the target cell of PRACH, the target cell ID / BWP ID / frequency may be indicated by DCI including the PDCCH order.

[0199] The network can specify multiple target cells in a DCI that includes a PDCCH order. The user interface (UE) may select one cell to trigger RACH based on the DCI.

[0200] In this disclosure, the PDCCH order may be included (applied) not only to DCI format 1_0, but also to other DCI formats such as DCI format 1_1, 1_2, 2_X, etc.

[0201] [Option 2-1] If a UE has an ongoing random access procedure triggered by a PDCCH order, and it receives another PDCCH order indicating the same target cell ID / BWP ID / center frequency / random access preamble / PRACH mask index / UL carrier, the procedure will be considered the same random access procedure as the ongoing one and will not be reinitialized.

[0202] According to Option 2, the UE can appropriately determine whether a candidate cell's PDCCH order triggers RACH based on the new rules.

[0203] Furthermore, for example, to reduce handover delays / interruptions, it has been agreed that the UE will perform the following steps in candidate cells before receiving an L1 / L2 cell switching command: • DL synchronization for candidate cells • TRS tracking for candidate cells • Obtain CSI for candidate cells. • Activation / Selection of the TCI status for candidate cells.

[0204] Furthermore, it is being investigated whether the above procedure can be performed even when the candidate cell is a deactive SCell.

[0205] However, considering scenarios involving distributed nodes (Distribution Units: DUs), it is anticipated that certain procedures may not be possible to execute on a candidate cell before the UE receives a cell switch command. For example, certain procedures may only be possible after the UE receives a cell switch command. In this case, the challenge lies in how to notify and control the UE's behavior regarding these functions / procedures on the candidate cell.

[0206] Therefore, new parameters may be introduced regarding the execution of specific functions / procedures before the UE receives a cell switching command.

[0207] The new parameter may be a parameter indicating whether a particular function / procedure can be executed. This new parameter may be set for each candidate cell when settings for multiple candidate cells are provided to the UE in RRC signaling.

[0208] [Aspect 1] For example, a new parameter may be a single bit of information (0 or 1) indicating whether a particular function / procedure is executable (Option 1). If the field of the new parameter is set to "1", the UE may execute a predefined / configured set of functions / procedures before receiving the cell switch command (it may be assumed to be executable). If the field of the new parameter is set to "0", the UE does not have to execute a predefined / configured set of functions / procedures before receiving the cell switch command (it may be assumed to be unexecutable).

[0209] Additionally, other new parameters may be defined to indicate a different set of functions / procedures (Option 2). Defining other new parameters (to indicate a different function / procedure) requires different bits of information.

[0210] These other new parameters (which may simply be called parameters) may indicate whether each candidate cell and the current serving cell are located in (belong to) a distributed node (e.g., a Distributed Unit (DU)) / central unit (CU), or different DUs / CUs. These parameters allow the UE to be instructed whether to perform certain steps before receiving a cell switching command.

[0211] For example, if the parameter field "0" is set for a candidate cell, the UE does not need to anticipate that signaling from the NW will trigger an unexpected function / procedure for the candidate cell, or the UE may ignore the fact that it receives signaling from the NW and will not trigger those functions / procedures.

[0212] For example, the field "0" of the parameter may indicate (or mean) that "CSI acquisition for candidate cells is not permitted before receiving a cell switching command." In this case, if the RRC's CSI measurement settings include a candidate cell indicated by the field "0" of the parameter, the UE may ignore the CSI measurement / CSI report for that candidate cell.

[0213] Each set may have at least one predefined / preconfigured feature / procedure: • DL synchronization for candidate cells • TRS tracking for candidate cells • Acquisition of the L1 beam to the candidate cell, or acquisition of CSI (measurement results of periodic, semi-persistent, or aperiodic CSI-RS in the candidate cell). • Activation / Selection of TCI status for candidate cells. • PRACH transmission in candidate cells, • SRS transmission in candidate cells, • Monitoring of PDCCH (corresponding to a specific format or CORESET / SS) in candidate cells.

[0214] As a variation, the RRC / MAC CE may select at least one of the predefined / preconfigured functions / procedures. The DCI / MAC CE may also instruct / invoke whether the selected set of functions / procedures should be applied to each candidate cell. For example, a DCI containing a PDCCH order may be used for this instruction. Whether a candidate cell is explicitly indicated may be indicated by the RRC / MAC CE / DCI or implicitly associated with the candidate cell for the triggered PRACH.

[0215] [Aspect 2] When a UE receives a cell switching command using DCI / MAC CE, a predefined / preconfigured set of functions / procedures / RSs may be triggered or activated for the specified target cell. The target cell may also be a candidate cell.

[0216] For example, the functions / procedures / RS indicated by field "0" of the new parameter described above (however their configurations are provided by RRC) may be assumed by the UE to be triggered / activated on the target cell if the cell switching command is a command on the target cell. In this case, the configuration of the functions / procedures / RS indicated by field "0" of the new parameter may be provided by RRC.

[0217] When a cell switching command is sent from the network to the user interface (UE), the cell switching command may include explicit instructions to trigger / activate a set of functions / procedures / RSs.

[0218] For example, in order to reduce the latency of data transmission in the target cell after the UE receives a cell switch command, the functions / procedures required for data transmission must be executed as early as possible, if they are not performed before the cell switch command.

[0219] Existing MAC CE content may include at least one of the following as a new cell switching command to trigger several functions / procedures: • Activation / deactivation of SCell / candidate cells, • Aperiodic CSI trigger state for the target cell, • Activation of the non-periodic CSI-RS / Channel State Information-Interference Measurement (CSI-IM) resource set for the target cell. • Activation of the TCI state for PDCCH / PDSCH for the target cell. • Timing advance command (TA command) for the target cell.

[0220] Some existing DCI instructions may include at least one of the following as a new cell switching command to trigger some functions / procedures: • PDCCH order to trigger RACH on target cell, • An indication to trigger aperiodic CSI reporting for the target cell.

[0221] Other new instructions may include at least one of the following: • When CFRA / CBRA PRACH configuration is enabled, the upper layer from which RACH is triggered, • Activation of settings related to L1 / CSI measurement / reporting.

[0222] Thus, by using the new parameters, for example, before the UE receives a cell switching command, the UE can perform tracking of the TRS and activation / deactivation of the TCI state of the candidate cell.

[0223] (Overview of L1L2-triggered mobility (LTM)) FIG. 9 is a diagram showing an overview of L1L2-triggered mobility (LTM). LTM and L1 / L2 inter-cell mobility may be read as each other. The UE receives candidate cell configurations from the NW during UE reconfiguration. UE reconfiguration includes T RRC T proccesing1 / Tproccesing2 T includes. RRC (For example, up to 10 ms) is the processing time for RRC Reconfiguration carrying candidate cell configurations. T proccesing1 / Tproccesing2 (For example, up to 20 ms for the same FR and up to 40 ms for different FRs) is the time for UE processing before and after the cell switching command. This may include L2 / 3 reconfiguration, RF retuning, baseband retuning, and security update if necessary.

[0224] DL synchronization includes T search T Δ T margin T includes. search (For example, 0 ms if the cell is known and up to 60 ms if the cell is unknown) is the time required to search for the target cell. T Δ is the time for fine tracking and obtaining all timing information. T margin (For example, up to 2 ms) is the time for post-processing of SSB and CSI-RS.

[0225] L1 measurement is T meas(Includes SMTC period (e.g., 20ms)). meas This represents the measurement delay from when the target appears until the cell switching command is issued.

[0226] UL synchronization (UL storage) is T IU , T RAR , T cmd Includes. IU (For example, up to 15ms) is the uncertain interruption time when acquiring the first available PRACH opportunity in a new cell. RAR (For example, a maximum of 4ms) is the RAR delay time. cmd (For example, a maximum of 5ms) is the processing time for L1 / L2 commands (HARQ and paging).

[0227] T cmd T after first-data This is the time after RAR when the UE performs its first DL receive / UL transmit on the target cell's indicator beam.

[0228] Figure 10 shows a PDCCH-ordered RACH (PDCCH ordered RACH) with random access response (RAR) monitoring for a serving cell. In this disclosure, source cell and source cell group may be interpreted as interchangeable. Similarly, candidate cell and candidate cell group may be interpreted as interchangeable.

[0229] The source cell sends candidate cell settings to the UE. The source cell then sends a RACH instruction (PDCCH order) to the UE using PDCCH (e.g., including DCI format 1_0). Note that in this instruction, only one candidate cell is specified due to the complexity of parallel RAR. The UE then sends a PRACH in the RACH procedure to the candidate cell in order to obtain TAG / TA.

[0230] Next, the source cell transmits RAR (TA indication) to the UE. In this case, since only one common search space (CSS) is configured, the RAR is monitored in the SpCell (only within the Distributed Unit (DU)). And the UE may transmit and receive in the current serving cell. And in the source cell, TA adjustment is performed.

[0231] Next, the source cell transmits a cell switch command to the UE. At this time, TA information can be transferred from the source cell to the target cell. In this case, after the first cell switch, UL synchronization of all candidate cells may not be completed. The UE performs the first UL transmission using the initial TA.

[0232] FIG. 11 is a diagram showing PDCCH ordered RACH without random access response (RAR) monitoring for candidate cells. Only the differences from FIG. 10 will be described for FIG. 11. In the example of FIG. 11, in the RACH indication (PDCCH order) by the PDCCH, a plurality of candidate cells may be indicated. The UE may transmit the PRACH in the RACH procedure to the candidate cells for acquiring a plurality of TAG / TA. And the source cell does not transmit the RAR, and transmits a TA indication in the cell switch command.

[0233] In the present disclosure, RACH without RAR may be read as RACH without RAR monitoring (for example, RACH without RAR monitoring). The RACH may be read as a PRACH transmission triggered by a PDCCH order. The RACH procedure / PRACH transmission without RAR monitoring may be read as a RACH procedure / PRACH transmission for which RAR monitoring is unnecessary or a RACH procedure / PRACH transmission for which RAR monitoring is not required.

[0234] Regarding LTM, each candidate cell configuration may include at least the upper layer parameters CellGroupConfig and the configuration ID.

[0235] In LTM, candidate cell settings support the delta setting being the top-level setting in the baseline settings. Here, with respect to the delta setting, the UE stores the baseline settings as a separate setting. In other words, baseline settings may be managed separately. For example, a separate baseline setting may be provided for the candidate cell delta setting.

[0236] A MAC CE containing LTM-related information for cell switching may be used as a trigger for LTM cell switching. LTM cell switching may be monitored by a timer. A MAC CE for cell switching commands may be used to indicate a connection to the target cell.

[0237] In LTM, the target cell (PCell / SCell) may be the current SCell / PCell. That is, the current SCell / PCell (serving cell) may be set as the candidate cell.

[0238] (MAC CE for cell switching command) The MAC CE for the cell switching command may include at least one of the following pieces of information: • Information to identify target cells, • Information regarding TA, • Beam direction for target cell (SpCell) • ID of the active DL BWP / UL BWP for the target cell (SpCell) • Triggering of aperiodic TRS transmitted from the target cell, • Triggering CSI acquisition for target cells, reporting to target cells, • Triggering aperiodic SRS transmission to target cells, • Whether a field corresponding to the above information exists (e.g., always exists, or is configurable), • The bit size of each field.

[0239] (RAR format) Figure 12 shows an example of the configuration of an existing RAR format (MAC RAR). As shown in Figure 12, an existing MAC RAR may consist of, for example, 7 octets (= 56 bits). Specifically, a MAC RAR may include a 1-bit reserved (R) field, a 12-bit TAC field, a 27-bit UL grant field, and a 16-bit Temporary Cell Radio Network Temporary Identifier (TC-RNTI) field.

[0240] The TAC field may contain information for adjusting the timing of uplink transmission, and the TC-RNTI field may contain temporary information (temporary terminal identifier) ​​for identifying the terminal.

[0241] (analysis) <Analysis 1> As mentioned above, the UE's behavior before receiving the cell switching command is being considered. However, even if the UE performs UL synchronization before receiving the cell switching command, there is a risk that, due to some problem, the NW (base station) may not be able to obtain the TA of the target candidate cell when deciding to send the cell switching command MAC CE. Here, some examples of problems include cases where the PDCCH order has been sent but the NW has not yet decoded the PRACH, or cases where the quality of the serving cell suddenly deteriorates and the TA has not yet been obtained.

[0242] Therefore, it is necessary to support a cell switching command to trigger PRACH on the target candidate cell.

[0243] <Analysis 2> Furthermore, as mentioned above, a timeline is defined between PDCCH order reception and PRACH transmission. Here, if the candidate cell is also the currently active serving cell (case 0), the existing timeline can be applied.

[0244] However, if the candidate cell is currently a deactive serving cell (Case 1), or if the candidate cell is not the current serving cell (Case 2), then the candidate cell (in Case 1 / 2) is considered deactivated, and may have a different frequency than the current active CC. Therefore, in Case 1 / 2, the current timeline is not appropriate, and the concept of additional time (time axis / time series / timeline) is considered necessary.

[0245] <Analysis 3> Furthermore, there are limitations to the RF chain of a UE. Therefore, if a PDCCH order to trigger PRACH is sent to the UE from a candidate cell on a different frequency than the currently active CC, the UE needs to adjust the RF transmission (Tx) of one of its active serving cells to the candidate cell. In this case, a connection (communication) interruption may occur in the currently active serving cell. Here, it is necessary to clarify that the NW / UE have a common understanding / awareness of how the current serving cell will be interrupted and for how long (time) it will be interrupted.

[0246] <Analysis 4> Furthermore, the primary use of RAR in the candidate cell's LTM is considered to be sending TA to the UE. Therefore, when RAR is configured in the PDCCH order RACH for a candidate cell, it is necessary to consider whether to apply the existing RAR as is or to apply a new RAR format.

[0247] As these analyses show, several considerations arise regarding the cell switching command used to trigger RACH on candidate cells. If these are not clearly defined, cell switching may not be properly controlled, potentially leading to a degradation in communication quality.

[0248] Therefore, the inventors of the present invention focused on a cell switching command for triggering RACH for candidate cells and conceived of one aspect of the present embodiment.

[0249] Hereinafter, embodiments according to the present disclosure will be described in detail with reference to the drawings. The wireless communication methods according to each embodiment may be applied individually or in combination.

[0250] (Various read conversions, etc.) In the present disclosure, "A / B" and "at least one of A and B" may be read interchangeably. Also, in the present disclosure, "A / B / C" may mean "at least one of A, B, and C".

[0251] In the present disclosure, notification, activate, deactivate, instruct (or specify (indicate)), select, configure, update, determine, etc. may be read interchangeably. In the present disclosure, support, control, be able to control, operate, be able to operate, etc. may be read interchangeably.

[0252] In the present disclosure, Radio Resource Control (RRC), RRC parameters, RRC messages, upper layer parameters, fields, Information Elements (IEs), settings, etc. may be read interchangeably. In the present disclosure, Medium Access Control control elements (MAC Control Elements (CEs)), update commands, activation / deactivation commands, etc. may be read interchangeably.

[0253] In the present disclosure, upper layer signaling may be any one of, for example, Radio Resource Control (RRC) signaling, Medium Access Control (MAC) signaling, broadcast information, or a combination thereof.

[0254] In this disclosure, MAC signaling may include, for example, MAC Control Elements (MAC CEs) and MAC Protocol Data Units (PDUs). Broadcast information may include, for example, Master Information Blocks (MIBs), System Information Blocks (SIBs), Remaining Minimum System Information (RMSIs), and Other System Information (OSIs).

[0255] In this disclosure, physical layer signaling may include, for example, Downlink Control Information (DCI) and Uplink Control Information (UCI).

[0256] In this disclosure, terms such as index, identifier (ID), indicator, and resource ID may be interpreted interchangeably. In this disclosure, terms such as sequence, list, set, group, cluster, and subset may be interpreted interchangeably.

[0257] In this disclosure, the terms used include: panel, UE panel, panel group, beam, beam group, precoder, Uplink (UL) transmit entity, Transmission / Reception Point (TRP), base station, Spatial Relation Information (SRI), spatial relationship, SRS Resource Indicator (SRI), Control Resource Set (CORESET), Physical Downlink Shared Channel (PDSCH), Codeword (CW), Transport Block (TB), Reference Signal (RS), antenna port (e.g., Demodulation Reference Signal (DMRS) port), antenna port group (e.g., DMRS port group), group (e.g., spatial relationship group, Code Division Multiplexing (CDM) group, reference signal group, CORESET group, Physical Uplink Control Channel (PUCCH) groups, PUCCH resource groups, resources (e.g., reference signal resources, SRS resources), resource sets (e.g., reference signal resource sets), CORESET pools, downlink Transmission Configuration Indication state (TCI state) (DL TCI state), uplink TCI state (UL TCI state), unified TCI state, common TCI state, quasi-co-location (QCL), QCL assumptions, etc., may be interpreted interchangeably.

[0258] Furthermore, the spatial relationship information Identifier (ID) (TCI state ID) and spatial relationship information (TCI state) may be interpreted as mutually exclusive. "Spatial relationship information" may be interpreted as mutually exclusive as "a set of spatial relationship information," "one or more spatial relationship information," etc. TCI state and TCI may be interpreted as mutually exclusive.

[0259] In this disclosure, TRP, CORESETPoolIndex, TRP ID, ID related to TRP, TAG ID, TCI status group, spatial relationship group, QCL source RS group, DL RS group, path loss RS group, and PCI (for inter-cell multi-TRP) may be interpreted as one another.

[0260] In this disclosure, being associated with different TRPs, being associated with different CORESET Pool Indexes (CORESETPoolIndex), being associated with different TRP IDs, being associated with different TRP IDs, being associated with different TAG IDs, being associated with different TCI state groups, being associated with different spatial relationship groups, being associated with different QCL source RS groups, being associated with different DL RS groups, being associated with different path loss RS groups, and being associated with different PCIs (for inter-cell multi-TRPs) may be interpreted as being associated with each other.

[0261] Each embodiment of this disclosure may be applied to at least one of intra-cell multi-TRP and inter-cell multi-TRP.

[0262] In this disclosure, intra-cell multi-TRP may mean that the activated TCI states of multiple (e.g., two) TRPs are associated with the same PCI.

[0263] In this disclosure, inter-cell multi-TRP may mean that the activated TCI states of multiple (e.g., two) TRPs are associated with different PCIs.

[0264] In this disclosure, in the case of inter-cell multi-TRPs, multiple (e.g., two) TRPs may mean multiple (e.g., two) TRPs associated with multiple (e.g., two) PCIs.

[0265] In this disclosure, non-serving cell, additional cell, candidate cell, and target cell may be interpreted as interchangeable.

[0266] In this disclosure, L1 / L2 inter-cell mobility, L1 / L2 intra-cell mobility, and L1L2-triggered mobility (LTM) may be interpreted interchangeably.

[0267] The following embodiments may apply when a RACH procedure is configured / supported for each TRP (or for each serving cell / additional cell / non-serving cell). Alternatively, the following embodiments may apply when a timing advance / timing advance group is configured / supported for each TRP (or for each serving cell / additional cell / non-serving cell).

[0268] (Wireless communication method) <First Embodiment> The first embodiment corresponds to Analysis 1 described above and relates to the MAC CE (field) for the cell switching command.

[0269] The UE may receive a MAC CE for a cell switching command to trigger a RACH on a target candidate cell. The target candidate cell may simply be called a candidate cell. The MAC CE for the cell switching command may simply be called a MAC CE. The MAC CE is used to instruct the triggering of a RACH on the candidate cell and may include at least one of the following fields. Note that the fields shown below primarily refer to the fields for instructing the RACH as described above. The MAC CE may include fields for other purposes, not limited to those shown below.

[0270] Alt1: An explicit field for indicating RACH for the specified candidate cell. The field may consist of a 1-bit field (0 or 1) indicating whether RACH is triggered or not. If CBRA is set for a candidate cell by higher-layer signaling regarding candidate cell configuration, the UE can perform CBRA. Also, if CFRA is set for a candidate cell by higher-layer signaling regarding candidate cell configuration, the UE can also perform CFRA.

[0271] Alt1-1: A 2-bit field indicating one of the following: non-RACH (no RACH applied), CFRA, or CBRA.

[0272] Alt1-2: No explicit field is required. Other fields (e.g., existing fields) may be reused for RACH indication. For example, the TA field may be used. A special value in the TA field may be used to indicate RACH / CFRA / CBRA. For example, a field indicating the presence of the TA field may be used to additionally indicate a RACH trigger.

[0273] Alt1-3: After receiving the MAC CE, the UE may decide to trigger RACH based on certain conditions. These conditions include, for example, when the cell switching command does not specify a TA value (the NW assumes that a TA has been acquired and maintained for the candidate cell), when the UE determines that there are no SR resources configured for UL data transmission, or when the UE determines that UL synchronization with the candidate cell has been lost.

[0274] Alt2: An explicit field for indicating at least one of the following: PRACH preamble index, PRACH mask index (for indicating PRACH resource occasion), beam index (SSB / CSI-RS), UL / SUL indication. Here, the MAC CE may be used to trigger a PDCCH order RACH. In this case, an additional beam index field is not required, and other fields such as the beam index / TCI status field of the indicated candidate cell can be reused. The UL / SUL field may be indicated by presence or absence depending on whether the candidate cell can set SUL.

[0275] According to the first embodiment described above, the UE can appropriately control the triggering of RACH for candidate cells based on the MAC CE for the cell switching command.

[0276] <Second Embodiment> The second embodiment corresponds to Analysis 1 described above and relates to the reception of RAR for RACH triggered in the first embodiment.

[0277] If the UE triggers the RACH described above and sends a PRACH to a candidate cell, it may receive RAR from the cells shown below.

[0278] Opt1: The original SpCell. Opt2: The target candidate cell. Note that the Type 1-CSS (set) setting may be provided by higher-layer signaling related to the candidate cell setting. Cells that receive Opt3:RAR may be pre-configured by upper-layer signaling or indicated by MAC CE for cell switching commands. Opt4: Cells receiving RARs may follow predefined rules. For example, for RACH RARs triggered before a cell switch command, the RAR may be monitored on the original SpCell. Alternatively, for RACH RARs triggered upon or after the reception of a cell switch command, the RAR may be monitored on a candidate cell indicated by the MAC CE for the cell switch command.

[0279] Furthermore, the second embodiment can also be applied to the PDCCH order RACH for candidate cells.

[0280] According to the second embodiment described above, the UE can properly receive the RAR transmitted from a specific cell.

[0281] <Third Embodiment> The third embodiment corresponds to Analysis 2 described above and concerns the time (timeline) between PDCCH order reception and PRACH transmission.

[0282] In the above-described cases 1 (when the candidate cell is currently a deactive serving cell) and 2 (when the candidate cell is not the current serving cell) of Analysis 2, an additional time Δ (delta) T (one of the following options) based on the current timeline may be defined as the time (timeline) from the last symbol of PDCCH order reception to the first symbol of PRACH transmission.

[0283] Opt1: The same (common) ΔT for cases 1 and 2. Opt2: Different ΔT in case 1 / 2.

[0284] ΔT may include the time to change to a deactive candidate cell / the time to change to a frequency different from the current active CC. ΔT may be predefined in the specification or may be set for the candidate cell by upper-layer signaling.

[0285] Furthermore, the third embodiment is also applicable to PDCCH order RACH for candidate cells. It is also applicable to MAC CE that triggers PDCCH order-like RACH for candidate cells.

[0286] Variations: Case 1 described above may be treated the same as Case 0 (when the candidate cell is also the currently active serving cell). Only for Case 2 may a new (additional) timeline be defined.

[0287] According to the third embodiment described above, the UE can determine the timeline for PDCCH order reception and PRACH transmission depending on the application case.

[0288] <Fourth Embodiment> The fourth embodiment corresponds to Analysis 3 described above and relates to a new upper-layer parameter for instructing / setting communication interruption during cell switching.

[0289] The new upper-layer parameter may indicate, in the configuration of each candidate cell, which serving cell's UL transmission will be interrupted when a PRACH / SRS transmission is performed for a candidate cell, and may be at least one of the following indications. The new upper-layer parameter may be represented by SwitchFromServCellIndex.

[0290] Variation 1: When triggering PRACH on a candidate cell, SwitchFromServCellIndex may be instructed by the DCI of the PDCCH order.

[0291] Variation 2: For candidate cells with the same frequency as the serving cell, SwitchFromServCellIndex is predefined as a serving cell with the same frequency, and no explicit setting is required. SwitchFromServCellIndex should only be set / displayed for candidate cells with a different frequency than the serving cell.

[0292] A cell to which SwitchFromServCellIndex is set may be a serving cell in the CA that has PUCCH / PUSCH transmission configured. Such cells may be limited to active serving cells. In this way, the cells to which it applies may be restricted.

[0293] When the PDCCH order RACH is triggered in a candidate cell, the interruption time in the serving cell of SwitchFromServCellIndex may be defined as the N1 symbol before the first symbol of PRACH, the PRACH transmission period (duration), and the N2 symbol after the last symbol of PRACH.

[0294] If the candidate cell and the serving cell with SwitchFromServCellIndex set have the same frequency, it is possible to support N1=0, N2=0.

[0295] If the candidate cell and the serving cell for which SwitchFromServCellIndex is set have different frequencies, N1 / N2 can be defined to larger values ​​(these may be predefined in the specification or supported by UE capabilities).

[0296] Figure 13 shows an example of switching from a serving cell to a candidate cell (target cell). As shown in Figure 13, if the SwitchFromServCellIndex set for candidate cell #3 is the same as that for serving cell #1 (e.g., SCell#1), the interruption time in serving cell #1 may be {PRACH period}.

[0297] Furthermore, if the SwitchFromServCellIndex set for candidate cell #4 is the same as that for serving cell #1, the interruption time in serving cell #1 may be {PRACH time + N1 + N2}. Here, N1 and N2 may be introduced as the time required for antenna / RF switching.

[0298] According to the fourth embodiment described above, the UE can determine whether communication is interrupted during cell switching based on the new upper-layer parameters.

[0299] <Fifth Embodiment> The fifth embodiment corresponds to Analysis 4 described above and relates to a new RAR format. Figure 14 shows an example of the new RAR format (MAC RAR). Figure 15 shows another example of the new RAR format (MAC RAR). Note that the field types and number of bits are merely examples and can be changed as appropriate.

[0300] If a PDCCH order RACH is triggered in a candidate cell and RAR reception is configured, the applicable RAR format may be at least one of the following options:

[0301] Opt1: Existing RAR formats, including the TAC, UL grant, TC-RNTI, and R fields, may be reused (see, for example, Figure 12).

[0302] Opt2: A new RAR format may be defined (see, for example, Figure 14 or Figure 15).

[0303] Opt2-1: Based on the existing RAR format, the UL grant field does not need to be included (see Figure 14). In this case, the only fields included in the new RAR format may be TAC, TC-RNTI, and R.

[0304] Opt2-2: The new RAR format may omit the UL grant field and TC-RNTI field, and may include only TAC and R.

[0305] Opt2-3: The new RAR format may include cell IDs that indicate candidate cells to which TA should be applied.

[0306] Note that TC-RNTI may also be C-RNTI assigned to UE in the candidate cell.

[0307] Furthermore, whether a new RAR format or an existing RAR format is used may be determined by upper-layer signaling (for each candidate cell / cell group or for all candidate cells), or it may be predefined (for example, applying the existing RAR format to both serving cells and candidate cells, and applying the new RAR format to candidate cells that are not serving cells).

[0308] Furthermore, whether a new RAR format or an existing RAR format is used may be indicated by the first R field of the RAR format, the LCID of the MAC RAR, or the PDCCH order.

[0309] Variations: To represent the TA of multiple cells with a single new RAR format, the RAR may include multiple fields of the TAC and multiple fields of the cell ID. As shown in Figure 15, instead of the R field, a bit indicating whether it is a new RAR format or an existing RAR format, i.e., a field (P field) indicating the presence or absence of a UL grant field, may be included. The P field may indicate the presence of octets 3-5 in Figure 15, for example.

[0310] According to the fifth embodiment described above, the UE can appropriately control UL transmission (e.g., timing advance) based on the novel RAR format.

[0311] <Supplement> [Notification of information to UE] In the embodiments described above, notification of any information from a Network (NW) (e.g., a Base Station (BS)) to a UE (in other words, reception of any information from a BS at the UE) may be performed using physical layer signaling (e.g., DCI), higher layer signaling (e.g., RRC signaling, MAC CE), specific signals / channels (e.g., PDCCH, PDSCH, reference signal), or a combination thereof.

[0312] If the above notification is made by a MAC CE, the MAC CE may be identified by the inclusion of a new Logical Channel ID (LCID) not defined in existing standards in the MAC subheader.

[0313] If the above notification is made by a DCI, the notification may be made by a specific field of the DCI, a Radio Network Temporary Identifier (RNTI) used to scramble the Cyclic Redundancy Check (CRC) bits assigned to the DCI, or the format of the DCI.

[0314] Furthermore, the notification of any information to the UE in the above-described embodiment may be periodic, semi-persistent, or aperiodic.

[0315] [Notification of information from UE] In the embodiments described above, notification of any information from the UE (to the NW) (in other words, transmission / reporting of any information from the UE to the BS) may be performed using physical layer signaling (e.g., UCI), higher layer signaling (e.g., RRC signaling, MAC CE), specific signals / channels (e.g., PUCCH, PUSCH, PRACH, reference signals), or a combination thereof.

[0316] If the above notification is made by a MAC CE, the MAC CE may be identified by the inclusion of a new LCID, not specified in existing standards, in the MAC subheader.

[0317] If the above notice is issued by the UCI, the notice may be sent using PUCCH or PUSCH.

[0318] Furthermore, the notification of any information from the UE in the above-described embodiments may be periodic, semi-persistent, or aperiodic.

[0319] [Regarding the application of each embodiment] At least one of the embodiments described above may be applied if certain conditions are met. These conditions may be specified in a standard or notified to the UE / BS using upper-layer signaling / physical layer signaling.

[0320] At least one of the embodiments described above may apply only to a UE that has reported or supports a particular UE capability.

[0321] The specific UE capability may represent at least one of the following: • To support specific processing / operation / control / information for at least one of the above embodiments. • To support mobility within L1 / L2 cells and mobility between L1 / L2 cells. • Support for TA (Technical Action) per TRP in intra-cell / inter-cell multi-TRP (Track Relay Program) scenarios. • Support for configuring intra-cell multi-TRP / inter-cell multi-TRP for serving cells / non-serving cells. • Support for changing the frame timing of the reference cell. • Support PDCCH monitoring of candidate cells / deactivated candidate cells / deactivated SCells. • Support the maximum number of cells / TAGs / reference CCs that are subject to PDCCH monitoring. • To support cross-carrier (cross-CC) PDCCH orders. • Support monitoring of RAR for candidate cells in candidate cells / SpCell / SCell. • Support the maximum number of candidate cells / SpCells / SCells subject to PDCCH monitoring. • Support for the execution of a specific set of functions / procedures in candidate cells (or deactivated cells) before receiving an L1 / L2 cell switching command, and support for a maximum number of such cells. • Support for RACH triggers during cell switching. • In Case 1 / 2, support for the time (timeline) between PDCCH order reception and PRACH transmission. • Support for the number of TA values ​​that the UE can store for candidate cells / serving cells before receiving a cell switching command in LTM.

[0322] Furthermore, the above-mentioned specific UE capabilities may be capabilities that apply across all frequencies (commonly regardless of frequency), capabilities per frequency (e.g., one or a combination thereof, such as cell, band, band combination, BWP, component carrier, etc.), capabilities per frequency range (e.g., Frequency Range 1 (FR1), FR2, FR3, FR4, FR5, FR2-1, FR2-2), capabilities per subcarrier spacing (SCS), or capabilities per feature set (FS) or feature set per component-carrier (FSPC).

[0323] Furthermore, the specific UE capabilities described above may be capabilities that apply across all duplexing schemes (common to all duplexing schemes), or they may be capabilities specific to each duplexing scheme (e.g., Time Division Duplex (TDD), Frequency Division Duplex (FDD)).

[0324] Furthermore, at least one of the embodiments described above may be applied when the UE is configured / activated / triggered by upper-layer signaling / physical-layer signaling to configure / activate specific information related to the embodiments described above (or to perform the actions of the embodiments described above). For example, such specific information may be information indicating the activation of random access procedures / PRACH transmissions without RAR monitoring, or arbitrary RRC parameters for a particular release (e.g., Rel. 18 / 19).

[0325] If the UE does not support at least one of the above-mentioned specific UE capabilities or does not have the above-mentioned specific information configured, the behavior of, for example, Rel.15 / 16 may be applied.

[0326] (Note) The following invention is added with respect to one embodiment of this disclosure. [Note 1] A receiving unit that receives a Medium Access Control Control Element (MAC CE) related to cell switching, The system includes a control unit that controls the triggering of a random access channel (RACH) for a candidate cell based on the information contained in the MAC CE, The MAC CE is a terminal that includes a field for instructing a RACH for the designated candidate cell. [Note 2] The receiving unit receives a random access response (RAR) for the trigger of the RACH from a specific cell. The control unit determines the specific cell that is the source of the RAR based on upper-layer signaling, as described in Appendix 1. [Note 3] The control unit determines, based on upper-layer signaling, the timeline for receiving physical downlink channel (PDCCH) orders and transmitting physical random access channel (PRACH), or the interruption of communication during cell switching, as described in Appendix 1 or Appendix 2 of the terminal. [Note 4] The receiving unit receives the Random Access Response (RAR) format for the trigger of the RACH, The control unit controls the uplink (UL) transmission timing advance based on the RAR format, and is a terminal as described in any of Appendix 1 to Appendix 3.

[0327] (Wireless communication system) The configuration of a wireless communication system according to one embodiment of this disclosure will be described below. In this wireless communication system, communication is performed using any or a combination thereof of the wireless communication methods according to the above embodiments of this disclosure.

[0328] Figure 16 shows an example of a schematic configuration of a wireless communication system according to one embodiment. The wireless communication system 1 (which may also be simply called system 1) may be a system that realizes communication using Long Term Evolution (LTE), 5th generation mobile communication system New Radio (5G NR), etc., as specified by the Third Generation Partnership Project (3GPP).

[0329] Furthermore, the wireless communication system 1 may support dual connectivity between multiple Radio Access Technologies (RATs) (Multi-RAT Dual Connectivity (MR-DC)). MR-DC may include dual connectivity between LTE (Evolved Universal Terrestrial Radio Access (E-UTRA)) and NR (E-UTRA-NR Dual Connectivity (EN-DC)), dual connectivity between NR and LTE (NR-E-UTRA Dual Connectivity (NE-DC)), and so on.

[0330] In EN-DC, the LTE (E-UTRA) base station (eNB) is the Master Node (MN), and the NR base station (gNB) is the Secondary Node (SN). In NE-DC, the NR base station (gNB) is the MN, and the LTE (E-UTRA) base station (eNB) is the SN.

[0331] The wireless communication system 1 may support dual connectivity between multiple base stations within the same RAT (for example, dual connectivity where both MN and SN are NR base stations (gNB) (NR-NR Dual Connectivity (NN-DC))).

[0332] The wireless communication system 1 may include a base station 11 that forms a macrocell C1 with relatively wide coverage, and base stations 12 (12a-12c) located within the macrocell C1 that form a small cell C2 that is narrower than the macrocell C1. User terminals 20 may be located within at least one cell. The arrangement and number of each cell and user terminal 20 are not limited to the configuration shown in the figure. Hereinafter, when base stations 11 and 12 are not distinguished, they will be collectively referred to as base station 10.

[0333] The user terminal 20 may be connected to at least one of the multiple base stations 10. The user terminal 20 may utilize at least one of Carrier Aggregation (CA) using multiple Component Carriers (CC) and Dual Connectivity (DC).

[0334] Each CC may be included in at least one of the first frequency band (Frequency Range 1 (FR1)) and the second frequency band (Frequency Range 2 (FR2)). A macrocell C1 may be included in FR1, and a small cell C2 may be included in FR2. For example, FR1 may be a frequency band of 6 GHz or less (sub-6 GHz), and FR2 may be a frequency band above 24 GHz (above-24 GHz). Note that the frequency bands and definitions of FR1 and FR2 are not limited to these, and for example, FR1 may fall in a frequency band higher than FR2.

[0335] Furthermore, the user terminal 20 may communicate using at least one of the following methods at each CC: Time Division Duplex (TDD) and Frequency Division Duplex (FDD).

[0336] Multiple base stations 10 may be connected by wire (e.g., optical fiber compliant with Common Public Radio Interface (CPRI), X2 interface, etc.) or wireless (e.g., NR communication). For example, if NR communication is used as a backhaul between base stations 11 and 12, base station 11, which is the upstream station, may be called an Integrated Access Backhaul (IAB) donor, and base station 12, which is the relay station, may be called an IAB node.

[0337] Base station 10 may be connected to the core network 30 via other base stations 10 or directly. The core network 30 may include at least one of the following: Evolved Packet Core (EPC), 5G Core Network (5GCN), Next Generation Core (NGC), etc.

[0338] The core network 30 may include network functions (NF) such as User Plane Function (UPF), Access and Mobility Management Function (AMF), Session Management Function (SMF), Unified Data Management (UDM), Application Function (AF), Data Network (DN), Location Management Function (LMF), and Operation, Administration and Maintenance (Management) (OAM). Multiple functions may be provided by a single network node. Furthermore, communication with an external network (e.g., the Internet) may occur via the DN.

[0339] The user terminal 20 may be a terminal that supports at least one of the following communication methods: LTE, LTE-A, 5G, etc.

[0340] In the wireless communication system 1, an orthogonal frequency division multiplexing (OFDM)-based wireless access scheme may be used. For example, Cyclic Prefix OFDM (CP-OFDM), Discrete Fourier Transform Spread OFDM (DFT-s-OFDM), Orthogonal Frequency Division Multiple Access (OFDMA), Single Carrier Frequency Division Multiple Access (SC-FDMA), etc., may be used in at least one of the downlink (DL) and uplink (UL).

[0341] The wireless access method may also be called a waveform. In wireless communication system 1, other wireless access methods (for example, other single-carrier transmission methods, other multi-carrier transmission methods) may be used for the UL and DL wireless access methods.

[0342] In the wireless communication system 1, a Physical Downlink Shared Channel (PDSCH), a Broadcast Channel (PBCH), or a Physical Downlink Control Channel (PDCCH) may be used as the downlink channel, shared by each user terminal 20.

[0343] Furthermore, in the wireless communication system 1, the uplink channel may include a Physical Uplink Shared Channel (PUSCH), a Physical Uplink Control Channel (PUCCH), a Physical Random Access Channel (PRACH), etc., shared by each user terminal 20.

[0344] User data, higher-layer control information, and System Information Blocks (SIBs) are transmitted via PDSCH. User data and higher-layer control information may also be transmitted via PUSCH. Furthermore, Master Information Blocks (MIBs) may be transmitted via PBCH.

[0345] Lower-layer control information may be transmitted by PDCCH. The lower-layer control information may include, for example, Downlink Control Information (DCI) which includes scheduling information for at least one of PDSCH and PUSCH.

[0346] Furthermore, the DCI that schedules PDSCH may be called a DL assignment or DL ​​DCI, and the DCI that schedules PUSCH may be called a UL grant or UL DCI. Furthermore, PDSCH may be interpreted as DL data, and PUSCH may be interpreted as UL data.

[0347] PDCCH detection may utilize a Control Resource Set (CORESET) and a search space. A CORESET corresponds to the resources used to search for DCIs. A search space corresponds to the search area and search method for PDCCH candidates. A single CORESET may be associated with one or more search spaces. The UE may monitor CORESETs associated with a particular search space based on the search space configuration.

[0348] A single search space may correspond to one or more PDCCH candidates corresponding to aggregation levels. One or more search spaces may be referred to as a search space set. In this disclosure, "search space," "search space set," "search space configuration," "search space set configuration," "CORESET," and "CORESET configuration" may be interpreted interchangeably.

[0349] PUCCH may transmit uplink control information (UCI) which includes at least one of the following: channel state information (CSI), delivery acknowledgment (e.g., Hybrid Automatic Repeat reQuest ACKnowledgement (HARQ-ACK), ACK / NACK, etc.), and scheduling request (SR). PRACH may transmit a random access preamble for establishing a connection with the cell.

[0350] In this disclosure, downlinks, uplinks, etc., may be expressed without the prefix "link." Also, the prefix "physical" may be omitted when describing various channels.

[0351] In the wireless communication system 1, a synchronization signal (SS), a downlink reference signal (DL-RS), etc., may be transmitted. In the wireless communication system 1, as DL-RS, a cell-specific reference signal (CRS), a channel state information reference signal (CSI-RS), a demodulation reference signal (DMRS), a positioning reference signal (PRS), a phase tracking reference signal (PTRS), etc., may be transmitted.

[0352] The synchronization signal may be, for example, at least one of a Primary Synchronization Signal (PSS) and a Secondary Synchronization Signal (SSS). A signal block including SS (PSS, SSS) and PBCH (and DMRS for PBCH) may be called an SS / PBCH block, SS Block (SSB), etc. SS, SSB, etc., may also be called reference signals.

[0353] Furthermore, in the wireless communication system 1, the Uplink Reference Signal (UL-RS) may transmit the Sounding Reference Signal (SRS), Demodulation Reference Signal (DMRS), etc. The DMRS may also be called the User-Specific Reference Signal (UE-specific Reference Signal).

[0354] (base station) Figure 17 shows an example of the configuration of a base station according to one embodiment. The base station 10 includes a control unit 110, a transceiver unit 120, a transceiver antenna 130, and a transmission line interface 140. Note that one or more of the control unit 110, transceiver unit 120, transceiver antenna 130, and transmission line interface 140 may be provided.

[0355] In this example, the functional blocks of the characteristic parts of this embodiment are mainly shown, and it may be assumed that the base station 10 also has other functional blocks necessary for wireless communication. Some of the processing of each part described below may be omitted.

[0356] The control unit 110 controls the entire base station 10. The control unit 110 can be composed of a controller, control circuit, etc., as described based on common understanding in the art relating to this disclosure.

[0357] The control unit 110 may control signal generation, scheduling (e.g., resource allocation, mapping), etc. The control unit 110 may also control transmission and reception, measurement, etc., using the transceiver unit 120, the transceiver antenna 130, and the transmission path interface 140. The control unit 110 may generate data to be transmitted as signals, control information, sequences, etc., and transfer them to the transceiver unit 120. The control unit 110 may also perform call processing of communication channels (setting, releasing, etc.), status management of the base station 10, management of radio resources, etc.

[0358] The transmitting / receiving unit 120 may include a baseband unit 121, a radio frequency (RF) unit 122, and a measurement unit 123. The baseband unit 121 may include a transmission processing unit 1211 and a reception processing unit 1212. The transmitting / receiving unit 120 can be composed of a transmitter / receiver, RF circuit, baseband circuit, filter, phase shifter, measurement circuit, transmitting / receiving circuit, etc., as described based on common understanding in the art relating to this disclosure.

[0359] The transmitting / receiving unit 120 may be configured as an integrated transmitting / receiving unit, or it may be composed of a transmitting unit and a receiving unit. The transmitting unit may consist of a transmitting processing unit 1211 and an RF unit 122. The receiving unit may consist of a receiving processing unit 1212, an RF unit 122 and a measuring unit 123.

[0360] The transmitting and receiving antenna 130 can be composed of an antenna described based on common understanding in the art relating to this disclosure, such as an array antenna.

[0361] The transmitting / receiving unit 120 may transmit the downlink channel, synchronization signal, downlink reference signal, etc. The transmitting / receiving unit 120 may also receive the uplink channel, uplink reference signal, etc.

[0362] The transmitting / receiving unit 120 may form at least one of the transmitting beam and the receiving beam using digital beamforming (e.g., precoding), analog beamforming (e.g., phase rotation), or the like.

[0363] The transmitting / receiving unit 120 (transmission processing unit 1211) may perform processing on data and control information acquired from the control unit 110, for example, at the Packet Data Convergence Protocol (PDCP) layer, the Radio Link Control (RLC) layer (e.g., RLC retransmission control), the Medium Access Control (MAC) layer (e.g., HARQ retransmission control), etc., to generate a bit sequence to be transmitted.

[0364] The transmitting / receiving unit 120 (transmission processing unit 1211) may perform transmission processing on the bit sequence to be transmitted, such as channel coding (which may include error correction coding), modulation, mapping, filtering, discrete Fourier transform (DFT) processing (if necessary), inverse fast Fourier transform (IFFT) processing, precoding, and digital-to-analog conversion, and output a baseband signal.

[0365] The transmitting / receiving unit 120 (RF unit 122) may perform modulation, filtering, amplification, etc., of the baseband signal to the radio frequency band and transmit the signal in the radio frequency band via the transmitting / receiving antenna 130.

[0366] On the other hand, the transmitting / receiving unit 120 (RF unit 122) may perform amplification, filtering, demodulation to a baseband signal, etc., on the radio frequency band signal received by the transmitting / receiving antenna 130.

[0367] The transmitting / receiving unit 120 (receiving processing unit 1212) may apply reception processing to the acquired baseband signal, such as analog-to-digital conversion, Fast Fourier Transform (FFT) processing, Inverse Discrete Fourier Transform (IDFT) processing (if necessary), filtering, demapping, demodulation, decoding (may include error correction decoding), MAC layer processing, RLC layer processing, and PDCP layer processing, to acquire user data, etc.

[0368] The transmitting / receiving unit 120 (measurement unit 123) may perform measurements related to the received signal. For example, the measurement unit 123 may perform Radio Resource Management (RRM) measurements, Channel State Information (CSI) measurements, etc., based on the received signal. The measurement unit 123 may also measure received power (e.g., Reference Signal Received Power (RSRP)), reception quality (e.g., Reference Signal Received Quality (RSRQ), Signal to Interference plus Noise Ratio (SINR), Signal to Noise Ratio (SNR)), signal strength (e.g., Received Signal Strength Indicator (RSSI)), propagation path information (e.g., CSI), etc. The measurement results may be output to the control unit 110.

[0369] The transmission path interface 140 may send and receive signals (backhaul signaling) with devices included in the core network 30 (e.g., network nodes providing NF), other base stations 10, etc., and may acquire and transmit user data (user plane data), control plane data, etc. for the user terminal 20.

[0370] In this disclosure, the transmitting and receiving units of the base station 10 may consist of at least one of a transmitting / receiving unit 120, a transmitting / receiving antenna 130, and a transmission path interface 140.

[0371] The transmitting / receiving unit 120 may transmit a Medium Access Control Element (MAC CE) related to cell switching. Based on the information contained in the MAC CE, the transmitting / receiving unit 120 may receive a random access channel (RACH) triggered for a candidate cell from the terminal.

[0372] (User terminal) Figure 18 shows an example of the configuration of a user terminal according to one embodiment. The user terminal 20 includes a control unit 210, a transmitting / receiving unit 220, and a transmitting / receiving antenna 230. Note that one or more of the control unit 210, the transmitting / receiving unit 220, and the transmitting / receiving antenna 230 may be provided.

[0373] In this example, the functional blocks of the characteristic parts of this embodiment are mainly shown, and it may be assumed that the user terminal 20 also has other functional blocks necessary for wireless communication. Some of the processing of each part described below may be omitted.

[0374] The control unit 210 controls the entire user terminal 20. The control unit 210 can be composed of a controller, control circuit, etc., as described based on common understanding in the technical field related to this disclosure.

[0375] The control unit 210 may control signal generation, mapping, etc. The control unit 210 may also control transmission and reception, measurement, etc., using the transmitting / receiving unit 220 and the transmitting / receiving antenna 230. The control unit 210 may generate data to be transmitted as signals, control information, sequences, etc., and transfer them to the transmitting / receiving unit 220.

[0376] The transmitting / receiving unit 220 may include a baseband unit 221, an RF unit 222, and a measurement unit 223. The baseband unit 221 may include a transmission processing unit 2211 and a reception processing unit 2212. The transmitting / receiving unit 220 can be composed of a transmitter / receiver, RF circuit, baseband circuit, filter, phase shifter, measurement circuit, transmitting / receiving circuit, etc., as described based on common understanding in the art relating to this disclosure.

[0377] The transmitting / receiving unit 220 may be configured as an integrated transmitting / receiving unit, or it may be composed of a transmitting unit and a receiving unit. The transmitting unit may consist of a transmitting processing unit 2211 and an RF unit 222. The receiving unit may consist of a receiving processing unit 2212, an RF unit 222 and a measuring unit 223.

[0378] The transmitting and receiving antenna 230 can be composed of an antenna described based on common understanding in the art relating to this disclosure, such as an array antenna.

[0379] The transmitting / receiving unit 220 may receive the downlink channel, synchronization signal, downlink reference signal, etc. The transmitting / receiving unit 220 may also transmit the uplink channel, uplink reference signal, etc.

[0380] The transmitting / receiving unit 220 may form at least one of the transmitting beam and the receiving beam using digital beamforming (e.g., precoding), analog beamforming (e.g., phase rotation), or the like.

[0381] The transmitting / receiving unit 220 (transmission processing unit 2211) may perform PDCP layer processing, RLC layer processing (e.g., RLC retransmission control), MAC layer processing (e.g., HARQ retransmission control), etc., on data and control information acquired from the control unit 210, etc., to generate a bit sequence to be transmitted.

[0382] The transmitting / receiving unit 220 (transmission processing unit 2211) may perform transmission processing on the bit sequence to be transmitted, such as channel coding (which may include error correction coding), modulation, mapping, filtering, DFT processing (if necessary), IFFT processing, precoding, and digital-to-analog conversion, and output a baseband signal.

[0383] Whether or not to apply DFT processing may be based on the transform precoding settings. The transmitting / receiving unit 220 (transmission processing unit 2211) may perform DFT processing as part of the transmission process to transmit a channel (for example, PUSCH) using a DFT-s-OFDM waveform if transform precoding is enabled for that channel, or it may not perform DFT processing as part of the transmission process if transform precoding is not enabled for that channel.

[0384] The transmitting / receiving unit 220 (RF unit 222) may perform modulation, filtering, amplification, etc., of the baseband signal to the radio frequency band and transmit the signal in the radio frequency band via the transmitting / receiving antenna 230.

[0385] On the other hand, the transmitting / receiving unit 220 (RF unit 222) may perform amplification, filtering, demodulation to a baseband signal, etc., on the radio frequency band signal received by the transmitting / receiving antenna 230.

[0386] The transmitting / receiving unit 220 (receiving processing unit 2212) may apply reception processing such as analog-to-digital conversion, FFT processing, IDFT processing (if necessary), filtering, demapping, demodulation, decoding (may include error correction decoding), MAC layer processing, RLC layer processing, and PDCP layer processing to the acquired baseband signal to acquire user data, etc.

[0387] The transmitting / receiving unit 220 (measuring unit 223) may perform measurements related to the received signal. For example, the measuring unit 223 may perform RRM measurement, CSI measurement, etc., based on the received signal. The measuring unit 223 may also measure received power (e.g., RSRP), received quality (e.g., RSRQ, SINR, SNR), signal strength (e.g., RSSI), propagation path information (e.g., CSI), etc. The measurement results may be output to the control unit 210.

[0388] The measurement unit 223 may derive channel measurements for CSI calculation based on channel measurement resources. Channel measurement resources may be, for example, Non Zero Power (NZP) CSI-RS resources. The measurement unit 223 may also derive interference measurements for CSI calculation based on interference measurement resources. Interference measurement resources may be at least one of the following: an NZP CSI-RS resource for interference measurement, a CSI-Interference Measurement (IM) resource, etc. CSI-IM may also be called CSI-Interference Management (IM), and may be interpreted interchangeably with Zero Power (ZP) CSI-RS. In this disclosure, CSI-RS, NZP CSI-RS, ZP CSI-RS, CSI-IM, CSI-SSB, etc., may be interpreted interchangeably.

[0389] In this disclosure, the transmitting and receiving units of the user terminal 20 may consist of at least one of a transmitting / receiving unit 220 and a transmitting / receiving antenna 230.

[0390] The transmitting / receiving unit 220 may receive a Medium Access Control Element (MAC CE) related to cell switching. The MAC CE may include a field for instructing a RACH to a designated candidate cell. The transmitting / receiving unit 220 may receive a Random Access Response (RAR) from a specific cell for the trigger of the RACH. The transmitting / receiving unit 220 may receive a Random Access Response (RAR) format for the trigger of the RACH.

[0391] The control unit 210 may control the triggering of a Random Access Channel (RACH) for a candidate cell based on the information contained in the MAC CE. The control unit 210 may determine the specific cell that is the source of the RAR based on upper-layer signaling. The control unit 210 may determine the timeline for receiving physical downlink channel (PDCCH) orders and transmitting physical random access channel (PRACH), or the interruption of communication during cell switching, based on upper-layer signaling. The control unit 210 may control the uplink (UL) transmit timing advance based on the RAR format.

[0392] (Hardware configuration) The block diagrams used in the description of the above embodiments show functional units. These functional blocks (components) are realized by any combination of at least one of hardware and software. Furthermore, the method of realizing each functional block is not particularly limited. That is, each functional block may be realized using one device that is physically or logically coupled, or it may be realized using two or more physically or logically separated devices that are directly or indirectly connected (for example, using wired or wireless connections). A functional block may also be realized by combining the above one device or the above multiple devices with software.

[0393] Here, functions include, but are not limited to, judgment, decision, determination, calculation, calculation, processing, derivation, investigation, search, confirmation, reception, transmission, output, access, resolution, selection, selection, establishment, comparison, assumption, expectation, consideration, broadcasting, notifying, communicating, forwarding, configuring, reconfiguring, allocating (mapping), and assigning. For example, a functional block (configuration part) that enables transmission may be called a transmitting unit or transmitter. In all cases, as mentioned above, the method of implementation is not particularly limited.

[0394] For example, a base station, user terminal, etc. in one embodiment of the present disclosure may function as a computer that processes the wireless communication method of the present disclosure. Figure 19 is a diagram showing an example of the hardware configuration of a base station and user terminal according to one embodiment. The base station 10 and user terminal 20 described above may be physically configured as a computer device including a processor 1001, memory 1002, storage 1003, communication device 1004, input device 1005, output device 1006, bus 1007, etc.

[0395] In this disclosure, terms such as apparatus, circuit, device, section, and unit are interchangeable. The hardware configuration of the base station 10 and the user terminal 20 may include one or more of the devices shown in the figure, or it may be configured to omit some of the devices.

[0396] For example, although only one processor 1001 is shown in the diagram, there may be multiple processors. Furthermore, processing may be performed by one processor, or by two or more processors simultaneously, sequentially, or by other means. Note that processor 1001 may be implemented using one or more chips.

[0397] Each function in the base station 10 and the user terminal 20 is realized, for example, by loading predetermined software (programs) onto hardware such as the processor 1001 and memory 1002, which allows the processor 1001 to perform calculations and control communication via the communication device 1004, or to control at least one of the reading and writing of data in the memory 1002 and storage 1003.

[0398] The processor 1001 controls the entire computer, for example, by running an operating system. The processor 1001 may be composed of a central processing unit (CPU) that includes interfaces with peripheral devices, control units, arithmetic units, registers, etc. For example, at least a part of the control unit 110 (210) and the transmitting / receiving unit 120 (220) described above may be implemented by the processor 1001.

[0399] Furthermore, the processor 1001 reads programs (program code), software modules, data, etc., from at least one of the storage 1003 and the communication device 1004 into the memory 1002 and executes various processes accordingly. The program used is one that causes the computer to execute at least a part of the operations described in the above embodiment. For example, the control unit 110 (210) may be implemented by a control program stored in the memory 1002 and running on the processor 1001, and other functional blocks may be implemented similarly.

[0400] Memory 1002 is a computer-readable recording medium and may consist of at least one of the following: Read Only Memory (ROM), Erasable Programmable ROM (EPROM), Electrically EPROM (EEPROM), Random Access Memory (RAM), or other suitable storage medium. Memory 1002 may also be called a register, cache, or main memory. Memory 1002 can store executable programs (program code), software modules, etc., for carrying out a wireless communication method according to one embodiment of this disclosure.

[0401] Storage 1003 is a computer-readable recording medium and may consist of at least one of the following: a flexible disk, a floppy disk, a magneto-optical disk (e.g., a compact disk (Compact Disc ROM (CD-ROM)), a digital multipurpose disk, a Blu-ray disk), a removable disk, a hard disk drive, a smart card, a flash memory device (e.g., a card, stick, key drive), a magnetic stripe, a database, a server, or other suitable storage medium. Storage 1003 may also be called an auxiliary storage device.

[0402] The communication device 1004 is hardware (transmitting / receiving device) for communicating between computers via at least one of a wired network and a wireless network, and is also referred to as a network device, network controller, network card, communication module, etc. The communication device 1004 may be configured to include, for example, a high-frequency switch, duplexer, filter, frequency synthesizer, etc., in order to implement at least one of frequency division duplex (FDD) and time division duplex (TDD). For example, the above-mentioned transmitting / receiving unit 120 (220), transmitting / receiving antenna 130 (230), etc., may be implemented by the communication device 1004. The transmitting / receiving unit 120 (220) may be implemented with physically or logically separated implementations of a transmitting unit 120a (220a) and a receiving unit 120b (220b).

[0403] The input device 1005 is an input device that accepts input from an external source (e.g., a keyboard, mouse, microphone, switch, button, sensor, etc.). The output device 1006 is an output device that outputs to an external source (e.g., a display, speaker, light-emitting diode (LED) lamp, etc.). The input device 1005 and the output device 1006 may be configured as an integrated unit (e.g., a touch panel).

[0404] Furthermore, each device, such as the processor 1001 and memory 1002, is connected by a bus 1007 for communicating information. The bus 1007 may be configured using a single bus, or different buses may be configured for each device.

[0405] Furthermore, the base station 10 and the user terminal 20 may be configured to include hardware such as a microprocessor, a digital signal processor (DSP), an application-specific integrated circuit (ASIC), a programmable logic device (PLD), and a field programmable gate array (FPGA), and some or all of each functional block may be implemented using such hardware. For example, the processor 1001 may be implemented using at least one of these hardware components.

[0406] (modified version) In addition, terms used in this disclosure and terms necessary for understanding this disclosure may be replaced with terms having the same or similar meanings. For example, channel, symbol, and signal (signal or signaling) may be used interchangeably. Also, a signal may be a message. A reference signal may be abbreviated as RS and may be called a pilot, pilot signal, etc., depending on the applicable standard. Also, a component carrier (CC) may be called a cell, frequency carrier, carrier frequency, etc.

[0407] A wireless frame may consist of one or more periods (frames) in the time domain. Each of these periods (frames) constituting a wireless frame may be called a subframe. Furthermore, a subframe may consist of one or more slots in the time domain. A subframe may have a fixed time length (e.g., 1 ms) that is independent of numerology.

[0408] Here, the neuralelogy may be communication parameters applied to at least one of the transmission and reception of a signal or channel. The neuralelogy may be, for example, at least one of the following: subcarrier spacing (SCS), bandwidth, symbol length, cyclic prefix length, transmission time interval (TTI), number of symbols per TTI, radio frame configuration, specific filtering processes performed by the transceiver in the frequency domain, or specific windowing processes performed by the transceiver in the time domain.

[0409] A slot may consist of one or more symbols in the time domain (such as Orthogonal Frequency Division Multiplexing (OFDM) symbols or Single Carrier Frequency Division Multiple Access (SC-FDMA) symbols). Alternatively, a slot may be a time unit based on neurology.

[0410] A slot may include multiple mini-slots. Each mini-slot may consist of one or more symbols in the time domain. Mini-slots may also be called sub-slots. Mini-slots may consist of fewer symbols than a slot. A PDSCH (or PUSCH) transmitted in a time unit larger than a mini-slot may be called a PDSCH (PUSCH) mapping type A. A PDSCH (or PUSCH) transmitted using a mini-slot may be called a PDSCH (PUSCH) mapping type B.

[0411] Wireless frames, subframes, slots, minislots, and symbols all represent units of time when transmitting a signal. Wireless frames, subframes, slots, minislots, and symbols may each be referred to by different names. Furthermore, the units of time such as frames, subframes, slots, minislots, and symbols in this disclosure may be interpreted as interchangeable.

[0412] For example, one subframe may be called TTI, multiple consecutive subframes may be called TTI, or one slot or one mini-slot may be called TTI. In other words, at least one of the subframe and TTI may be a subframe (1ms) in existing LTE, a period shorter than 1ms (e.g., 1-13 symbols), or a period longer than 1ms. Note that the unit representing TTI may be called a slot, mini-slot, etc., instead of a subframe.

[0413] Here, TTI refers to, for example, the smallest unit of time for scheduling in wireless communication. For example, in an LTE system, the base station schedules each user terminal to allocate wireless resources (such as the frequency bandwidth and transmission power available to each user terminal) in TTI units. However, the definition of TTI is not limited to this.

[0414] TTI may be a transmission time unit for channel-encoded data packets (transport blocks), code blocks, code words, etc., or it may be a processing unit for scheduling, link adaptation, etc. Given a TTI, the actual time interval (e.g., number of symbols) to which the transport block, code block, code word, etc. are mapped may be shorter than the given TTI.

[0415] Furthermore, if one slot or one mini-slot is referred to as TTI, then one or more TTIs (i.e., one or more slots or one or more mini-slots) may constitute the minimum time unit of scheduling. In addition, the number of slots (number of mini-slots) that constitute the minimum time unit of scheduling may be controlled.

[0416] A TTI with a time length of 1 ms may also be called a normal TTI (TTI in 3GPP Rel.8-12), a long TTI, a normal subframe, a long subframe, or a slot. A TTI shorter than a normal TTI may also be called a shortened TTI, a short TTI, a partial or fractional TTI, a shortened subframe, a short subframe, a mini slot, a sub slot, or a slot.

[0417] Furthermore, long TTIs (e.g., normal TTIs, subframes, etc.) may be interpreted as TTIs with a time length exceeding 1 ms, and short TTIs (e.g., shortened TTIs, etc.) may be interpreted as TTIs with a TTI length less than that of a long TTI but 1 ms or more.

[0418] A Resource Block (RB) is a resource allocation unit in the time domain and frequency domain, and in the frequency domain, it may contain one or more consecutive subcarriers. The number of subcarriers in an RB may be the same regardless of the neurology, for example, 12. The number of subcarriers in an RB may be determined based on the neurology.

[0419] Furthermore, an RB may contain one or more symbols in the time domain and may have the length of one slot, one minislot, one subframe, or one TTI. Each TTI, subframe, etc., may consist of one or more resource blocks.

[0420] One or more RBs may also be called Physical RBs (PRBs), Sub-Carrier Groups (SCGs), Resource Element Groups (REGs), PRB pairs, RB pairs, etc.

[0421] Furthermore, a resource block may consist of one or more resource elements (REs). For example, one RE may be a radio resource area comprising one subcarrier and one symbol.

[0422] A Bandwidth Part (BWP) (also called a partial bandwidth) may represent a subset of consecutive common resource blocks (RBs) for a given neurology in a given carrier. Here, the common RBs may be identified by an index of the RBs relative to the carrier's common reference point. PRBs may be defined and numbered within a BWP.

[0423] A BWP may include UL BWPs (BWPs for UL) and DL BWPs (BWPs for DL). One or more BWPs may be configured within a single carrier for a UE.

[0424] At least one of the configured BWPs may be active, and the UE does not need to assume that it will send or receive a given signal / channel outside of the active BWP. In this disclosure, terms such as "cell" and "carrier" may be read as "BWP".

[0425] The structures described above, such as wireless frames, subframes, slots, minislots, and symbols, are merely illustrative examples. For instance, the number of subframes included in a wireless frame, the number of slots per subframe or wireless frame, the number of minislots within a slot, the number of symbols and RBs included in a slot or minislot, the number of subcarriers included in an RB, and the number of symbols, symbol length, and cyclic prefix (CP) length within a TTI can be varied in various ways.

[0426] Furthermore, the information, parameters, etc., described in this disclosure may be expressed using absolute values, relative values ​​from a predetermined value, or corresponding other information. For example, wireless resources may be indicated by a predetermined index.

[0427] The names used for parameters and other elements in this disclosure are not restrictive in any way. Furthermore, mathematical formulas and other elements that use these parameters may differ from those expressly disclosed in this disclosure. Various channels (PUCCH, PDCCH, etc.) and information elements can be identified by any suitable name, and therefore, the various names assigned to these various channels and information elements are not restrictive in any way.

[0428] The information, signals, etc. described in this disclosure may be represented using any of the various different techniques. For example, the data, instructions, commands, information, signals, bits, symbols, chips, etc. that may be referred to throughout the above description may be represented by voltage, current, electromagnetic waves, magnetic fields or magnetic particles, optical fields or photons, or any combination thereof.

[0429] Furthermore, information, signals, etc., can be output from upper layers to lower layers and from lower layers to upper layers, or to at least one of the two. Information, signals, etc., may also be input and output via multiple network nodes.

[0430] Input and output information and signals may be stored in a specific location (e.g., memory) or managed using a management table. Input and output information and signals may be overwritten, updated, or appended to. Output information and signals may be deleted. Input information and signals may be transmitted to other devices.

[0431] Information notification is not limited to the embodiments described herein and may be carried out by other means. For example, information notification in this disclosure may be carried out by physical layer signaling (e.g., Downlink Control Information (DCI), Uplink Control Information (UCI)), higher layer signaling (e.g., Radio Resource Control (RRC) signaling, broadcast information (Master Information Block (MIB), System Information Block (SIB)), Medium Access Control (MAC) signaling), other signals, or a combination thereof).

[0432] Physical layer signaling may also be called Layer 1 / Layer 2 (L1 / L2) control information (L1 / L2 control signals), L1 control information (L1 control signals), etc. RRC signaling may also be called RRC messages, for example, RRC Connection Setup messages, RRC Connection Reconfiguration messages, etc. MAC signaling may also be communicated using, for example, MAC Control Element (CE).

[0433] Furthermore, notification of the specified information (for example, notification that "X is the case") is not limited to explicit notification, but may also be made implicitly (for example, by not providing notification of the specified information or by providing notification of other information).

[0434] The determination may be made by a value represented by 1 bit (0 or 1), by a boolean value represented as true or false, or by a numerical comparison (for example, a comparison with a predetermined value).

[0435] Software should be broadly interpreted to mean instructions, instruction sets, code, code segments, program code, programs, subprograms, software modules, applications, software applications, software packages, routines, subroutines, objects, executable files, execution threads, procedures, functions, and so on, whether they are called software, firmware, middleware, microcode, hardware description languages, or by any other name.

[0436] Furthermore, software, instructions, information, etc., may be transmitted and received via a transmission medium. For example, if software is transmitted from a website, server, or other remote source using at least one of wired technology (such as coaxial cable, fiber optic cable, twisted pair, or Digital Subscriber Line (DSL)) and wireless technology (such as infrared or microwave), then at least one of these wired and wireless technologies is included in the definition of a transmission medium.

[0437] The terms “system” and “network” as used in this disclosure may be used interchangeably. “Network” may also mean the equipment included in the network (e.g., base stations).

[0438] In this disclosure, terms such as “precoding,” “precoder,” “weight (precoding weight),” “quasi-co-location (QCL),” “transmission configuration indication state (TCI state),” “spatial relation,” “spatial domain filter,” “transmit power,” “phase rotation,” “antenna port,” “layer,” “number of layers,” “rank,” “resource,” “resource set,” “beam,” “beam width,” “beam angle,” “antenna,” “antenna element,” “panel,” “UE panel,” “transmitting entity,” and “receiving entity” may be used interchangeably.

[0439] In this disclosure, "antenna port" may be interpreted interchangeably with "antenna port for any signal / channel" (e.g., a Demodulation Reference Signal (DMRS) port). In this disclosure, "resource" may be interpreted interchangeably with "resource for any signal / channel" (e.g., a reference signal resource, an SRS resource, etc.). Resources may include time / frequency / code / spatial / power resources. Furthermore, a spatial domain transmit filter may include at least one of a spatial domain transmit filter and a spatial domain receive filter.

[0440] The above group may include, for example, at least one of the following: a spatial relationship group, a code division multiplexing (CDM) group, a reference signal (RS) group, a control resource set (CORESET) group, a PUCCH group, an antenna port group (e.g., a DMRS port group), a layer group, a resource group, a beam group, an antenna group, or a panel group.

[0441] Furthermore, in this disclosure, beam, SRS Resource Indicator (SRI), CORESET, CORESET pool, PDSCH, PUSCH, Codeword (CW), Transport Block (TB), RS, etc., may be interpreted as being interchangeable.

[0442] Furthermore, in this disclosure, TCI state, downlink TCI state (DL TCI state), uplink TCI state (UL TCI state), unified TCI state, common TCI state, joint TCI state, etc., may be interpreted interchangeably.

[0443] Furthermore, in this disclosure, terms such as "QCL," "QCL assumption," "QCL relationship," "QCL type information," "QCL properties," "specific QCL type (e.g., type A, type D) properties," and "specific QCL type (e.g., type A, type D)" may be interpreted as interchangeable.

[0444] In this disclosure, terms such as index, identifier (ID), indicator, indication, and resource ID may be interpreted interchangeably. In this disclosure, terms such as sequence, list, set, group, cluster, subset, etc., may be interpreted interchangeably.

[0445] Furthermore, the spatial relationship information Identifier (ID) (TCI state ID) and spatial relationship information (TCI state) may be interpreted as mutually exclusive. "Spatial relationship information (TCI state)" may be interpreted as mutually exclusive as "a set of spatial relationship information (TCI state)," "one or more spatial relationship information," etc. TCI state and TCI may be interpreted as mutually exclusive. Spatial relationship information and spatial relationship may be interpreted as mutually exclusive.

[0446] In this disclosure, terms such as "Base Station (BS)", "wireless base station", "fixed station", "NodeB", "eNB (eNodeB)", "gNB (gNodeB)", "access point", "Transmission Point (TP)", "Reception Point (RP)", "Transmission / Reception Point (TRP)", "panel", "cell", "sector", "cell group", "carrier", and "component carrier" may be used interchangeably. Base stations may also be referred to by terms such as macrocell, small cell, femtocell, and picocell.

[0447] A base station can house one or more (e.g., three) cells. If a base station houses multiple cells, the entire coverage area of ​​the base station can be divided into several smaller areas, each of which may also be provided with communication services by a base station subsystem (e.g., a small indoor base station (Remote Radio Head (RRH))). The terms “cell” or “sector” refer to part or all of the coverage area of ​​at least one of the base station and / or base station subsystems that provide communication services in that coverage.

[0448] In this disclosure, the transmission of information by a base station to a terminal may be interpreted as the base station instructing the terminal to perform a control / operation based on said information.

[0449] In this disclosure, terms such as "Mobile Station (MS)," "user terminal," "User Equipment (UE)," and "terminal" may be used interchangeably.

[0450] A mobile station may also be called a subscriber station, mobile unit, subscriber unit, wireless unit, remote unit, mobile device, wireless device, wireless communication device, remote device, mobile subscriber station, access terminal, mobile terminal, wireless terminal, remote terminal, handset, user agent, mobile client, client, or some other appropriate term.

[0451] At least one of the base station and the mobile station may be called a transmitting device, a receiving device, a wireless communication device, etc. At least one of the base station and the mobile station may also be a device mounted on a moving object, the moving object itself, etc.

[0452] The term "mobile object" refers to any movable object, regardless of its speed, and naturally includes cases where the mobile object is stationary. Examples of such mobile objects include, but are not limited to, vehicles, transport vehicles, automobiles, motorcycles, bicycles, connected cars, excavators, bulldozers, wheel loaders, dump trucks, forklifts, trains, buses, handcarts, rickshaws, ships and other watercraft, airplanes, rockets, satellites, drones, multicopters, quadcopters, balloons, and items carried on them. Furthermore, such mobile objects may be autonomously driven objects operating based on operational commands.

[0453] The mobile entity may be a vehicle (e.g., a car, an airplane), an unmanned mobile entity (e.g., a drone, an autonomous vehicle), or a robot (manned or unmanned). At least one of the base station and the mobile station may be a device that does not necessarily move during communication operations. For example, at least one of the base station and the mobile station may be an Internet of Things (IoT) device such as a sensor.

[0454] Figure 20 shows an example of a vehicle according to one embodiment. The vehicle 40 includes a drive unit 41, a steering unit 42, an accelerator pedal 43, a brake pedal 44, a shift lever 45, left and right front wheels 46, left and right rear wheels 47, an axle 48, an electronic control unit 49, various sensors (including a current sensor 50, a rotation speed sensor 51, a pneumatic pressure sensor 52, a vehicle speed sensor 53, an acceleration sensor 54, an accelerator pedal sensor 55, a brake pedal sensor 56, a shift lever sensor 57, and an object detection sensor 58), an information service unit 59, and a communication module 60.

[0455] The drive unit 41 consists of, for example, at least one of an engine, a motor, or an engine-motor hybrid. The steering unit 42 includes at least a steering wheel (also called a handle) and is configured to steer at least one of the front wheels 46 and the rear wheels 47 based on the operation of the steering wheel operated by the user.

[0456] The electronic control unit 49 consists of a microprocessor 61, memory (ROM, RAM) 62, and communication ports (e.g., input / output (IO) ports) 63. Signals from various sensors 50-58 installed in the vehicle are input to the electronic control unit 49. The electronic control unit 49 may also be called an Electronic Control Unit (ECU).

[0457] Signals from various sensors 50-58 include current signals from current sensor 50 for sensing motor current, rotational speed signals of front wheels 46 / rear wheels 47 acquired by rotational speed sensor 51, air pressure signals of front wheels 46 / rear wheels 47 acquired by air pressure sensor 52, vehicle speed signals acquired by vehicle speed sensor 53, acceleration signals acquired by acceleration sensor 54, accelerator pedal depression signal of accelerator pedal 43 acquired by accelerator pedal sensor 55, brake pedal depression signal of brake pedal 44 acquired by brake pedal sensor 56, operation signals of shift lever 45 acquired by shift lever sensor 57, and detection signals for detecting obstacles, vehicles, pedestrians, etc., acquired by object detection sensor 58.

[0458] The information service unit 59 consists of various devices for providing (outputting) various types of information such as driving information, traffic information, and entertainment information, including a car navigation system, audio system, speakers, displays, television, and radio, and one or more ECUs that control these devices. The information service unit 59 uses information acquired from external devices via a communication module 60 or the like to provide various types of information / services (e.g., multimedia information / multimedia services) to the occupants of the vehicle 40.

[0459] The information service unit 59 may include input devices that accept input from the outside (e.g., keyboard, mouse, microphone, switch, button, sensor, touch panel, etc.) and output devices that perform output to the outside (e.g., display, speaker, LED lamp, touch panel, etc.).

[0460] The driver assistance system unit 64 consists of various devices that provide functions to prevent accidents or reduce the driver's workload, such as millimeter-wave radar, Light Detection and Ranging (LiDAR), cameras, positioning locators (e.g., Global Navigation Satellite System (GNSS)), map information (e.g., High Definition (HD) maps, Autonomous Vehicle (AV) maps), gyro systems (e.g., Inertial Measurement Unit (IMU), Inertial Navigation System (INS)), artificial intelligence (AI) chips, and AI processors, as well as one or more ECUs that control these devices. The driver assistance system unit 64 also transmits and receives various information via the communication module 60 to realize driver assistance functions or autonomous driving functions.

[0461] The communication module 60 can communicate with the microprocessor 61 and components of the vehicle 40 via the communication port 63. For example, the communication module 60 sends and receives data (information) via the communication port 63 to the drive unit 41, steering unit 42, accelerator pedal 43, brake pedal 44, shift lever 45, left and right front wheels 46, left and right rear wheels 47, axle 48, the microprocessor 61 and memory (ROM, RAM) 62 in the electronic control unit 49, and various sensors 50-58 provided in the vehicle 40.

[0462] The communication module 60 is a communication device that can be controlled by the microprocessor 61 of the electronic control unit 49 and can communicate with external devices. For example, it can send and receive various types of information to and from external devices via wireless communication. The communication module 60 may be located either inside or outside the electronic control unit 49. The external device may be, for example, the base station 10 or the user terminal 20 described above. Alternatively, the communication module 60 may be, for example, at least one of the base station 10 and the user terminal 20 (it may function as at least one of the base station 10 and the user terminal 20).

[0463] The communication module 60 may transmit at least one of the following to an external device via wireless communication: signals from the various sensors 50-58 input to the electronic control unit 49, information obtained based on said signals, and information based on input from an external source (user) obtained via the information service unit 59. The electronic control unit 49, the various sensors 50-58, the information service unit 59, etc., may also be called input units that accept input. For example, the PUSCH transmitted by the communication module 60 may include information based on the above input.

[0464] The communication module 60 receives various information (traffic information, signal information, inter-vehicle information, etc.) transmitted from an external device and displays it on the information service unit 59 installed in the vehicle. The information service unit 59 may also be called an output unit, which outputs information (for example, it outputs information to devices such as displays and speakers based on the PDSCH (or data / information decoded from the PDSCH) received by the communication module 60).

[0465] Furthermore, the communication module 60 stores various information received from external devices in a memory 62 that can be used by the microprocessor 61. Based on the information stored in the memory 62, the microprocessor 61 may control the drive unit 41, steering unit 42, accelerator pedal 43, brake pedal 44, shift lever 45, left and right front wheels 46, left and right rear wheels 47, axle 48, various sensors 50-58, etc., which are provided in the vehicle 40.

[0466] Furthermore, the term "base station" in this disclosure may be interpreted as "user terminal." For example, the various aspects / embodiments of this disclosure may be applied to a configuration in which communication between a base station and a user terminal is replaced with communication between multiple user terminals (which may be called, for example, Device-to-Device (D2D), Vehicle-to-Everything (V2X)). In this case, the user terminal 20 may have the functions that the base station 10 has. Also, terms such as "uplink" and "downlink" may be interpreted as terms corresponding to terminal-to-terminal communication (for example, "sidelink"). For example, uplink channel and downlink channel may be interpreted as sidelink channel.

[0467] Similarly, the term "user terminal" in this disclosure may be replaced with "base station." In this case, the base station 10 may be configured to have the same functions as the user terminal 20 described above.

[0468] In this disclosure, operations performed by a base station may, in some cases, be performed by its upper node. In a network including one or more network nodes with base stations, it is clear that various operations performed for communication with terminals may be performed by the base station, one or more network nodes other than the base station (for example, a Mobility Management Entity (MME), a Serving Gateway (S-GW), etc., but not limited to these), or a combination thereof.

[0469] Each aspect / embodiment described in this disclosure may be used individually, in combination, or switched between during execution. Furthermore, the processing procedures, sequences, flowcharts, etc., of each aspect / embodiment described in this disclosure may be rearranged in order, provided they are consistent. For example, the methods described in this disclosure present various step elements in an exemplary order and are not limited to that specific order.

[0470] Each aspect / embodiment described in this disclosure includes Long Term Evolution (LTE), LTE-Advanced (LTE-A), LTE-Beyond (LTE-B), SUPER 3G, IMT-Advanced, 4th generation mobile communication system (4G), 5th generation mobile communication system (5G), 6th generation mobile communication system (6G), xth generation mobile communication system (xG (where x is, for example, an integer or decimal)), Future Radio Access (FRA), New-Radio Access Technology (RAT), New Radio (NR), New radio access (NX), Future generation radio access (FX), Global System for Mobile communications (GSM®), CDMA2000, Ultra Mobile Broadband (UMB), IEEE 802.11 (Wi-Fi®), IEEE 802.16 (WiMAX®), and IEEE This may apply to systems utilizing 802.20, Ultra-WideBand (UWB), Bluetooth®, or other appropriate wireless communication methods, as well as next-generation systems that are extended, modified, created, or defined based on these. It may also apply to combinations of multiple systems (e.g., a combination of LTE or LTE-A and 5G).

[0471] In this disclosure, the phrase "based on" does not mean "based solely on" unless otherwise specified. In other words, the phrase "based on" means both "based solely on" and "based at least on."

[0472] Any reference to elements using the designations “first,” “second,” etc., as used in this disclosure does not generally limit the quantity or order of those elements. These designations may be used in this disclosure as a convenient way to distinguish between two or more elements. Accordingly, the references to the first and second elements do not imply that only two elements may be employed or that the first element must precede the second element in any way.

[0473] The term “determining” as used in this disclosure may encompass a wide variety of actions. For example, “determining” may be considered to include judging, calculating, computing, processing, deriving, investigating, looking up, searching, inquiry (e.g., searching in tables, databases, or other data structures), ascertaining, etc.

[0474] Furthermore, "judgment (decision)" may be considered as "judging (deciding)" things like receiving (e.g., receiving information), transmitting (e.g., sending information), input, output, accessing (e.g., accessing data in memory).

[0475] Furthermore, "judgment (decision)" may be considered as "judging (deciding)" something like resolving, selecting, choosing, establishing, comparing, etc. In other words, "judgment (decision)" may be considered as "judging (deciding)" something about an action. In this disclosure, "judgment (decision)" may be interpreted interchangeably with the actions described above.

[0476] Furthermore, in this disclosure, “determine / determining” may be interpreted as “assume / assuming,” “expect / expecting,” or “consider / considering.” In addition, in this disclosure, “not assuming that…” may be interpreted as “assuming that…”

[0477] In this disclosure, “expect” may be interpreted as “be expected.” For example, “expect(s) …” (where “...” may be expressed as a that clause, an infinitive, etc.) may be interpreted as “be expected ….” “does not expect …” may be interpreted as “be not expected ….” Furthermore, “An apparatus A is not expected …” may be interpreted as “An apparatus B other than apparatus A does not expect …” (for example, if apparatus A is a UE, apparatus B may be a base station).

[0478] The term "maximum transmit power" as used in this disclosure may mean the maximum transmit power, the nominal UE maximum transmit power, or the rated UE maximum transmit power.

[0479] As used in this disclosure, the terms “connected,” “coupled,” and any variations thereof mean any direct or indirect connection or coupling between two or more elements, and may include one or more intermediate elements between two elements that are “connected” or “coupled” with each other. The coupling or connection between elements may be physical, logical, or a combination thereof. For example, “connection” may be replaced with “access.”

[0480] In this disclosure, when two elements are connected, they can be considered to be “connected” or “coupled” to each other using one or more wires, cables, printed electrical connections, etc., and, in some non-exclusive and non-exclusive examples, electromagnetic energy having wavelengths in the radio frequency domain, microwave domain, or optical domain (both visible and invisible).

[0481] In this disclosure, the term "A and B are different" may mean "A and B are different from each other." The term may also mean "A and B are each different from C." Terms such as "separate" and "combine" may be interpreted similarly to "different."

[0482] Where the terms “include,” “including,” and variations thereof are used in this disclosure, these terms are intended to be inclusive, as is the term “comprising.” Furthermore, the term “or” as used in this disclosure is not intended to mean exclusive OR.

[0483] In this disclosure, if articles are added by translation, such as a, an, and the in English, this disclosure may include the fact that the noun following these articles is plural.

[0484] In this disclosure, terms such as "less than or equal to," "less than," "greater than or equal to," "more than," and "equal to" may be interpreted interchangeably. In addition, in this disclosure, terms meaning "good," "bad," "big," "small," "high," "low," "early," "slow," "wide," and "narrow" may be interpreted interchangeably, not limited to the positive, comparative, and superlative degrees. Furthermore, in this disclosure, terms meaning "good," "bad," "big," "small," "high," "low," "early," "slow," "wide," and "narrow" may be interpreted interchangeably, not limited to the positive, comparative, and superlative degrees, by adding "i-th" (where i is any integer) to the expression (for example, "highest" may be interpreted interchangeably with "i-th highest").

[0485] In this disclosure, "of," "for," "regarding," "related to," and "associated with" may be interpreted as being interchangeable.

[0486] In this disclosure, phrases such as "when A, B", "if A, then B", "B upon A", "B in response to A", "B based on A", "B during / while A", "B before A", "B at (the same time as) / on A", "B after A", "B since A", and "B until A" may be interchangeable. Furthermore, A, B, etc., may be replaced with appropriate expressions such as nouns, gerunds, or regular sentences depending on the context. The time difference between A and B may be approximately 0 (immediately after or immediately before). Additionally, a time offset may be applied to the time when A occurs. For example, "A" may be interpreted as "before / after the time offset when A occurs". The time offset (e.g., one or more symbols / slots) may be predetermined or determined by the UE based on the information provided.

[0487] In this disclosure, timing, time, duration, time instance, any unit of time (e.g., slot, subslot, symbol, subframe), period, occasion, resource, etc., may be interpreted interchangeably.

[0488] Although the invention described herein has been explained in detail above, it will be clear to those skilled in the art that the invention described herein is not limited to the embodiments described herein. The descriptions herein are illustrative and not intended to be restrictive in any way to the invention described herein.

Claims

1. A receiving unit that receives Medium Access Control Element (MAC CE) related to cell switching, The system includes a control unit that controls the triggering of a random access channel (RACH) for a candidate cell based on the information contained in the MAC CE, The MAC CE is a terminal that includes a field for instructing a RACH for the indicated candidate cell.

2. The receiving unit receives a random access response (RAR) to the trigger of the RACH from a specific cell. The terminal according to claim 1, wherein the control unit determines the specific cell that is the source of the RAR based on higher layer signaling.

3. The terminal according to claim 1, wherein the control unit determines, based on upper-layer signaling, the timeline for receiving physical downlink channel (PDCCH) orders and transmitting physical random access channel (PRACH), or the interruption of communication during cell switching.

4. The receiving unit receives the Random Access Response (RAR) format for the RACH trigger, The terminal according to claim 1, wherein the control unit controls the uplink (UL) transmission timing advance based on the RAR format.

5. The steps include receiving a Medium Access Control Element (MAC CE) related to cell switching, The step of controlling the triggering of a random access channel (RACH) for a candidate cell based on the information contained in the MAC CE, A wireless communication method for a terminal, wherein the MAC CE includes a field for indicating a RACH for an indicated candidate cell.

6. A transmission unit that sends a Medium Access Control Element (MAC CE) related to cell switching, The system includes a receiving unit that receives a random access channel (RACH) triggered for a candidate cell from a terminal based on the information contained in the MAC CE, The MAC CE is a base station that includes a field for indicating RACH for a designated candidate cell.

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