PUSCH transmission based on srs triggered by cell change order

Abstract

Example embodiments of this disclosure relate to methods, apparatus, and computer-readable storage medium communication in a terminal device, comprising: at least one processor; and at least one memory storing instructions that, when executed by the at least one processor, cause the terminal device to at least: receive configuration from one or more network nodes, the configuration including at least configuration for transmitting a probe reference signal for mobility operations between a serving cell and one or more candidate cells; and, after receiving a cell handover command from one or more network nodes, transmit the probe reference signal toward one or more candidate cells (530) based on a trigger for transmitting the probe reference signal, the probe reference signal being received after the transmission of at least one first uplink message.

Description

Technical Field

[0001] Various exemplary embodiments of this disclosure are generally related to the telecommunications field, and more specifically to methods, apparatuses, devices, and computer-readable storage media for cell handover procedures. Background Technology

[0002] When the UE (User Equipment) is powered on, it selects a cell in the PLMN (Public Land Mobile Network) to camp on. After camping on that cell, the UE monitors system information, performs measurements on the serving cell and neighboring cells based on measurement rules, and selects a better cell to camp on based on cell reselection criteria.

[0003] L1 / L2 triggered mobility, or low-layer triggered mobility (LTM), is a cell handover procedure in which the serving cell (PCell or PSCell) of a UE (User Equipment) is handed over by the network by sending an LTM cell handover command. Currently, it is assumed that the LTM handover command is delivered using MAC (Media Scrambling Control) signaling via the MAC CE (Media Access Control Element). Therefore, not using RRC (Radio Resource Control) signaling for L3 (Layer 3) based handover is one of the current methods used for handover between cells. LTM cell handover decisions are based on L1 (Layer 1) measurements performed and reported by the UE using L1 measurement reports. Measurements and reports are based on the LTM candidate cell configuration provided by the network for one or more LTM candidate cells. LTM candidate cells can be neighboring cells or the UE's current serving cell (e.g., SCell).

[0004] To maintain high data transmission efficiency during cell handover, Rel-19 LTM has agreed to acquire CSI based on downlink reference signals for candidate cells. Summary of the Invention

[0005] In a first aspect of this disclosure, a terminal device (510) for wireless communication is provided, the terminal device including at least one processor (531); and at least one memory (532) storing instructions that, when executed by the at least one processor (531), cause the terminal device (510) to at least: receive (502) a configuration from one or more network nodes (515), the configuration including at least a configuration (503) for transmitting a probe reference signal (513b), the probe reference signal (513b) b) Mobility operations between the serving cell (520) and one or more candidate cells (530); and after receiving (540) a cell handover command (514b) from one or more network nodes (515), sending (566) a probe reference signal (513b) toward one or more candidate cells (530) based on a trigger (509b) for sending (566) a probe reference signal (513b), which is received after the transmission (564) of at least one first uplink message (563). In a second aspect of this disclosure, a terminal device (510) for wireless communication is provided, the terminal device (510) including: components for receiving (502) configuration from one or more network nodes (515), the configuration including at least configuration (503) for transmitting a probe reference signal (513b) for mobility operation between a serving cell (520) and one or more candidate cells (530);

[0006] The component is used to send a probe reference signal (513b) toward one or more candidate cells (530) based on a trigger (509b) for sending a probe reference signal (513b) after receiving a cell handover command (540) from one or more network nodes (515), the probe reference signal (513b) being received after the transmission (564) of at least one first uplink message (563).

[0007] In a third aspect of this disclosure, a method for wireless communication is provided, the method comprising: receiving (502) a configuration by a terminal device (510) from one or more network nodes (515), the configuration including at least a configuration (503) for transmitting a probe reference signal (513b) for mobility operations between a serving cell (520) and one or more candidate cells (530); and, after receiving (540) a cell handover command (514b) from one or more network nodes (515), transmitting (566) the probe reference signal (513b) toward one or more candidate cells (530) based on a trigger (509b) for transmitting (566) the probe reference signal (513b), the probe reference signal (513b) being received after the transmission (564) of at least one first uplink message (563).

[0008] In a fourth aspect of this disclosure, a computer-readable medium is provided. The computer-readable medium includes instructions stored thereon for causing a terminal device (510) for wireless communication to at least perform the method according to the third aspect.

[0009] It should be understood that the summary portion is not intended to identify key or essential features of the embodiments of this disclosure, nor is it intended to limit the scope of this disclosure. Other features of this disclosure will become readily apparent from the following description. Attached Figure Description

[0010] Some exemplary embodiments will now be described with reference to the accompanying drawings, in which:

[0011] Figure 1 The diagram illustrates the signal flow of the L1 / L2 triggered mobility (LTM) process based on TS 38.300;

[0012] Figure 2 The diagram illustrates the process of acquiring CSI (Channel State Information) before LTM cell handover;

[0013] Figure 3 The diagram illustrates the LTM cell handover command MAC CE (Media Access Control Unit).

[0014] Figures 4A to 4C The illustrations depict various MAC CE field formats according to some example embodiments of this disclosure;

[0015] Figures 4D to 4E The illustration shows the determination of LTM SRS transmission timing according to some example embodiments of the present disclosure;

[0016] Figure 5A and Figure 5BCell handover environments according to some example embodiments of this disclosure are described; and

[0017] Figure 5C The diagram illustrates a signal flow diagram of an L1 / L2 triggered mobility (LTM) detection reference signal process according to some example embodiments of the present disclosure.

[0018] Throughout the accompanying drawings, the same or similar reference numerals may denote the same or similar elements. Detailed Implementation

[0019] The principles of this disclosure will now be described with reference to some exemplary embodiments. It should be understood that these embodiments are described for illustrative purposes only and to assist those skilled in the art in understanding and implementing this disclosure, and do not imply any limitation on the scope of this disclosure. The disclosure described herein can be implemented in various ways other than those described below. Where applicable, reference numerals may be used in multiple figures to illustrate different embodiments or implementations.

[0020] In the following description and claims, unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure pertains.

[0021] In this disclosure, references to "an embodiment," "an embodiment," "an example embodiment," etc., indicate that the described embodiments may include specific features, structures, or characteristics, but not every embodiment necessarily includes that specific feature, structure, or characteristic. Furthermore, such phrases do not necessarily refer to the same embodiment. Additionally, when a specific feature, structure, or characteristic is described in connection with an embodiment, those skilled in the art will recognize that, whether explicitly described or not, incorporating other embodiments to affect such a feature, structure, or characteristic is within their knowledge.

[0022] It should be understood that although the terms "first" and "second," etc., preceding the noun(s) may be used herein to describe various elements, these elements should not be limited by these terms. These terms are used only to distinguish one element from another, and they do not restrict the order of the noun(s). For example, without departing from the scope of the exemplary embodiments, a first element may be referred to as a second element, and similarly, a second element may be referred to as a first element. As used herein, the term "and / or" includes any and all combinations of one or more of the listed terms.

[0023] As used herein, “one or more of the following: ” and “<at least one of the two or more elements>” and similar wording (where the list of two or more elements is connected by “and” or “or”) means at least any one of these elements, or at least any two or more of these elements, or at least all of these elements.

[0024] As used herein, unless explicitly stated otherwise, “responding to A” does not mean that the step must be performed immediately after “A” occurs, but rather allows for one or more intermediate steps.

[0025] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments. As used herein, the singular forms “a,” “an,” and “the” are also intended to include the plural forms unless the context clearly indicates otherwise. It will also be understood that when the terms “comprising,” “including,” “having,” “having,” “including,” and / or “containing” are used herein, the presence of the stated features, elements, and / or components is specified, but the presence or addition of one or more other features, elements, components, and / or combinations thereof is not excluded.

[0026] As used in this application, the term "circuit system" may refer to one or more or all of the following: (a) Hardware circuit implementation only (such as implementation only in analog and / or digital circuit systems); and (b) A combination of hardware circuitry and software, such as (if applicable): (i) A combination of (multiple) analog and / or digital hardware circuits having software / firmware, and (ii) Any part of a hardware processor(s) having software (including (multiple) digital signal processors, software, and (multiple) memories, which work together to enable a device (such as a mobile phone or server) to perform various functions); and (c) (multiple) hardware circuits and / or (multiple) processors, such as (multiple) microprocessors or a portion thereof, which require software (e.g., firmware) to operate, but may be absent when operation is not required.

[0027] This definition of circuit system applies to all uses of the term in this application (including in any claim). As another example, as used in this application, the term circuit system also covers only hardware circuitry or a processor (or multiple processors) or portions of hardware circuitry or a processor and its accompanying software and / or firmware implementation. For example, and if applicable to a particular claim element, the term circuit system also covers baseband integrated circuits or processor integrated circuits for mobile devices, or similar integrated circuits in servers, cellular network devices or other computing or network devices.

[0028] As used herein, the term "communication network" refers to a network that conforms to any suitable communication standard, such as New Radio (NR), Long Term Evolution (LTE), LTE-A Advanced (LTE-A), Wideband Code Division Multiple Access (WCDMA), High-Speed ​​Packet Access (HSPA), Narrowband Internet of Things (NB-IoT), etc. Furthermore, communication between terminal devices and network devices in the communication network can be performed according to any suitable intergenerational communication protocol, including but not limited to first-generation (1G), second-generation (2G), 2.5G, 2.75G, third-generation (3G), fourth-generation (4G), 4.5G, fifth-generation (5G), 5.5G, sixth-generation (6G) communication protocols, and / or any other currently known or to be developed in the future. Embodiments of this disclosure can be applied to various communication systems. Due to the rapid development of communication, there will naturally be future types of communication technologies and systems that can be utilized to implement this disclosure. The scope of this disclosure should not be considered limited to the systems described above.

[0029] As used herein, the term "network node" or "network device" refers to a node in a communication network through which terminal devices access the network and receive services. Network devices can refer to base stations (BS) or access points (APs), such as Node B (NodeB or NB), evolved Node B (eNodeB or eNB), NR NB (also known as gNB), Remote Radio Unit (RRU), Radio Header (RH), Remote Radio Header End (RRH), relay, Integrated Access and Backhaul (IAB) node, low-power node (such as femtoseconds, picoseconds), non-terrestrial network (NTN), or non-terrestrial network equipment (such as satellite network equipment, low Earth orbit (LEO) satellites and geostationary orbit (GEO) satellites, aircraft network equipment, etc.), depending on the terminology and technologies applied. In some example embodiments, the Radio Access Network (RAN) split architecture includes centralized units (CUs) and distributed units (DUs) at the IAB donor node. The IAB node consists of: the mobile terminal (IAB-MT) part, which behaves like a UE to the parent node, and the DU part of the IAB node, which behaves like a base station to the next-hop IAB node.

[0030] The term "serving cell" can refer to the "source cell".

[0031] The term "terminal device" refers to any terminal device capable of wireless communication. As an example and not a limitation, a terminal device may also be referred to as a communication device, user equipment (UE), subscriber station (SS), portable subscriber station, mobile station (MS), or access terminal (AT). Terminal devices may include, but are not limited to, mobile phones, cellular phones, smartphones, Voice over IP (VoIP) phones, wireless local loop phones, tablets, wearable terminal devices, personal digital assistants (PDAs), portable computers, desktop computers, image capture terminal devices (such as digital cameras), gaming terminal devices, music storage and playback devices, in-vehicle wireless terminal devices, wireless endpoints, mobile stations, laptop embedded devices (LEEs), laptop devices (LMEs), USB dongles, smart devices, wireless customer premises equipment (CPEs), Internet of Things (IoT) devices, watches or other wearable devices, head-mounted displays (HMDs), vehicles, drones, medical devices and applications (e.g., remote surgery), industrial devices and applications (e.g., robots and / or other wireless devices operating in industrial and / or automated processing chain environments), consumer electronic devices, devices operating on commercial and / or industrial wireless networks, etc. The terminal device may also correspond to the mobile terminal (MT) portion of an IAB node (e.g., a relay node). In the following description, the terms "terminal device," "communication device," "terminal," "user equipment," and "UE" are used interchangeably.

[0032] As used herein, the terms “resource,” “transmission resource,” “resource block,” “physical resource block” (PRB), “uplink resource,” or “downlink resource” can refer to any resource used to perform communication, such as communication between a terminal device and a network device, including time-domain resources, frequency-domain resources, spatial-domain resources, code-domain resources, or any other combination of time-domain resources, frequency-domain resources, spatial-domain resources, and / or code-domain resources used to enable communication. In the following, unless explicitly stated otherwise, resources in both the frequency and time domains will be used as examples of transmission resources to describe some exemplary embodiments of this disclosure. It should be noted that the exemplary embodiments of this disclosure are equally applicable to other resources in other domains.

[0033] Figure 1 The diagram illustrates the signal flow of the L1 / L2 triggered mobility (LTM) procedure based on TS 38.300. In version 18, LTM measurements for neighboring candidate cells can be performed using a synchronization signal block (SSB) sent by the candidate cell, for which the SSB configuration is provided to the user equipment (UE) (or terminal equipment) (110).

[0034] Before switching from the serving cell (120) to the target cell (130a), at least one network (115a, ..., 115n) (collectively referred to as network 115) may optionally activate one or more TCI states for one or more candidate cells (130a, ..., 130n) (see [link to TCI state]). Figure 1 (Step 4a). After the candidate cell TCI state is activated, the UE (110) can begin tracking time / frequency synchronization using reference signals associated with the activated TCI states(s). The UE can also perform early UL synchronization prior to cell handover if requested by a network node (see [link to relevant documentation]). Figure 1 (Step 4b).

[0035] The procedure for LTM is referenced below (step numbers in section 9.2.3.5.2 of TS 38.300):

[0036] The UE (110) can be in the RRC_connected state with the serving cell (120) via a network node or gNB (115a) (at the initial preparation step of LTM (140) before cell handover).

[0037] Step 1. The UE (110) can send a message to the gNB (115a) in the serving cell (120). L3 RRC Measurement Report Message (142). gNB (115a) (i.e., the serving cell (120)) can decide to configure LTM and initiate LTM preparation.

[0038] Step 2. The serving cell (120) may send the LTM candidate configuration (146) to the UE (110). RRCReconfiguration Message (144).

[0039] Step 3. The UE (110) can store the LTM candidate configuration and send it to the serving cell (120). RRCReconfigurationComplete information.

[0040] During LTM execution (150), the following steps may be performed.

[0041] Step 5. In the first option, the UE (110) can perform L1 measurements on (a plurality of) configured LTM candidate cells and send an L1 measurement report (L1 CSI report) (142) to the serving cell (120).

[0042] In another option, the UE (110) can perform L3 measurements on (multiple) configured LTM candidate cells (130a to 130n) and transmit another RRC Measurement Report (142) Initiate LTM execution.

[0043] Provided that RRC reconfiguration (step 2) applies, L1 and L3 (i.e., lower-level) measurements should be performed.

[0044] Step 4a. The UE (110) may perform early DL synchronization (152) with (multiple) LTM candidate cells (130a to 130n) before receiving the cell handover command (156). The UE (110) may activate and deactivate the TCI state of (multiple) LTM candidate cells, as triggered by the serving cell (120) via TCI state activation (MAC CE) (153).

[0045] Step 4b. After early DL synchronization (152) is completed, the UE may perform early UL synchronization (154) with (a plurality of) LTM candidate cells (130a to 130n) by using UE-based TA measurement (if configured) and / or by sending a preamble (310b) to candidate cells (130a to 130n), as triggered by network node 115a (i.e., or serving cell (120)). When UE-based TA measurement is configured, the UE (110) may acquire (a plurality of) TA values ​​of (a plurality of) candidate cells (130a to 130n) by measurement. Before receiving the cell handover command (156), the UE performs early TA acquisition for (a plurality of) candidate cells (130a to 130n) at the request of network node (115a), as specified in Clause 9.2.6 of TS 38.300. This is performed via a CFRA triggered by a PDCCH command downlink control information (DCI) from the source cell (120b), after which the UE (110) can send a preamble (310b) toward a designated candidate cell (130a) as the target cell. To minimize data interruption in the source cell (120b) due to CFRAs of the candidate cells (130a to 130n), the UE (110) can receive a random access response (RAR) from the network node (115a) for purposes other than TA value acquisition, and the TA value of the candidate cell is indicated as the target cell (130a) in the cell handover command. The UE does not maintain a TA timer for the candidate cell, but relies on the network implementation to ensure TA validity.

[0046] Step 6. The gNB (115a) decides to perform a cell handover to the target cell (130a) and sends an LTM cell handover command (MAC CE) (156) that triggers the handover, including a target configuration ID (302b) indicating the candidate configuration of the target cell, a beam indicated by the TCI state (306a), or a beam indicated by the DL and ULTCI states (308a), and a timing advance command (304a) for the target cell (130a) (if available). The UE (110) may handover to the target cell (130a) and apply the candidate configuration indicated by the target configuration ID (302a).

[0047] Step 7. If the UE (110) does not have a valid TA for the target cell (130a), the UE (110) may perform a random access procedure (158) to the target cell (130a) as specified in Clause 5.18.35 of TS 38.321.

[0048] Step 8. The UE (110) can send a message to the target cell (130a). RRCReconfigurationComplete The message completes the LTM cell handover process. If the UE (110) has already performed the Random Access Notice (RACH) procedure in step 7, the UE can consider the LTM cell handover to have been successfully completed when the random access procedure is successfully completed. For LTM without RACH, the UE considers the LTM cell handover to have been successfully completed when it determines that the network has successfully received its first UL data.

[0049] Steps 4-8 can be performed multiple times (i.e., repeated 314a) to allow subsequent LTM cell handover execution using the (multiple) LTM candidate configurations (146) provided in step 2.

[0050] The air interface (F1-C) procedures described in Figure 9.2.3.5.2-1 of TS 38.300 apply to both intra-gNB-DU LTM and inter-gNB-DU LTM. The overall LTM procedures on the F1-C interface are documented in TS 38.401.

[0051] Figure 2 The diagram illustrates the process of acquiring CSI (Channel State Information) before LTM cell handover.

[0052] Early TCI State Activation (Early DL Synchronization): When supported by the UE (110), it is possible to activate the TCI states of one or more LTM candidate cells (130a to 130n) before sending the cell handover command (156). This early TCI activation allows the UE (110) to perform DL synchronization (152) with the cell associated with the activated TCI state, thereby facilitating a faster handover to one of these cells when a cell handover is triggered. If the TCI state of a candidate cell is not activated before the cell handover, the TCI state activation will occur along with the cell handover command. Then, since the UE (110) may need time for fine-grained time tracking in the candidate cells, an additional delay is added to the handover delay.

[0053] Early CSI (Channel State Information) Acquisition in Rel-19 LTM. Rel-19 considers NR mobility enhancements. One topic discussed is the CSI acquisition process before / during LTM cell handover. Three alternatives are investigated: - Alt-1: CSI-RS (Channel State Information Reference Signal) Measurement - And the CSI report operation (151) is performed before the LTM cell handover command (CSC) MAC CE (156) is received. - The report (147A) is sent to the serving cell (120) and transmitted to (multiple) candidate / target cells (130) (see See Figure 2 ). - Alt-2 (see Alt-2) Figure 2 ): CSI-RS measurement (151) can begin before the LTM CSC MAC CE is received, and CSI report (147B) operation is performed after the LTM CSC MAC CE (156) is received. - The report (147B) was sent directly to the target cell (130a). - Alt-3: CSI-RS measurement (151) and CSI reporting operations are performed after the LTM CSC MAC CE (156) is received.

[0054] During RAN1#119, it was agreed to support the above alternatives 2 and 3, more specifically: as a baseline, CSI-RS measurements (151) and CSI reporting operations (147B) are performed after the receipt of LTM CSC MAC CE (156). - The report (147B) was sent directly to the target cell (130a). - The introduction of UE capability for CSI-RS measurement (151) can begin before the reception of LTM CSC MAC CE (156). ○ In addition to UE capabilities, avoid creating additional specification effects compared to the baseline (specify only one triggering mechanism).

[0055] Table 7.3.1.1.2-24 provides the SRS request in 38.212 for reference.

[0056] Table 7.3.1.1.2-24: SRS Request

[0057] The SRS configuration provided in 38.331 is for reference only: IE SRS-Config This configuration is used to configure the transmission of the probe reference signal. It defines the SRS-Resource list and the SRS-ResourceSet list. Each resource set defines an SRS resource set. The network uses the configured aperiodicSRS-ResourceTrigger (L1 DCI) to trigger the transmission of the SRS resource set.

[0058] Figure 3 The diagram illustrates the LTM cell handover command MAC CE (300) (Media Access Control Unit). Note 2: If the UE (110) receives the LTM cell handover command MAC CE, the LTM cell handover command MAC CE has a configuration that does not match any settings. ltm-CandidateId If the target configuration ID value (302b) is reduced by 1, as specified in TS 38.331[5], then the process of handling the LTM cell handover command MAC CE in Clause 5.18.35 is not applicable.

[0059] LTM cell handover command MAC CE (300A) The LTM cell handover command MAC CE is identified by a MAC subheader with eLCID, as shown in Table 6.2.1-1b. It has a variable size and contains the following fields (Figure 6.1.3.75-1): - R: Reserved bit, set to 0; - Target Configuration ID (302b): This field indicates the index of the candidate target configuration to be applied to LTM cell handover, corresponding to... ltm-CandidateId Subtract 1, as specified in TS 38.331[5]. The length of this field is 3 bits; - Timing Advance Command (304a): This field indicates whether the TA is valid for the LTM target cell (i.e., the SpCell corresponding to the target configuration indicated by the Target Configuration ID field). If the value of this field is set to FFF, this field indicates that there is no valid timing adjustment available for the LTM target cell's PTAG; otherwise, this field indicates the index value of the timing adjustment amount that the MAC entity must apply in TS38.213[6]. T A And the UE can skip the random access procedure for handover to that LTM cell. If tag-Id-ptr Configured for the TCI status indicated by the UL TCI status ID field (if present) or the TCI status ID field in the LTM target cell, and tag-Id-ptr Set as value n1 Then this field indicates the target cell of LTM. tag2-Id The field indicates the TA of the TAG; otherwise, it indicates the target cell's TA by LTM. tag-id The TA of the indicated TAG. This field is 12 bits long; - TCI Status ID (306a): This field indicates and activates the TCI status for the LTM target cell (i.e., the SpCell of the target configuration indicated by the Target Configuration ID field). The TCI status is determined by... ltm-DL-OrJointTCI- StateToAddModList In TCI-StateId The identifier, as specified in TS 38.331[5]. If the configuration is indicated by the target configuration ID field. ltm-TCI-Info In unifiedTCI-StateType The value is joint If the condition is met, this field is used for the joint TCI status; otherwise, this field is used for the downlink TCI status. This field is 7 bits long. - UL TCI Status ID (308a): This field indicates and activates the uplink TCI status for the LTM target cell (i.e., the SpCell of the target configuration indicated by the Target Configuration ID field). The UL TCI status is determined by... ltm-UL-TCI- StateToAddModList In TCI-UL-StateId The identifier, as specified in TS 38.331[5]. If the configuration is indicated by the target configuration ID field. ltm-TCI-Info In unifiedTCI-StateType The value is separate If so, then the octet containing the field (i.e., the field and two reserved bits in the same octet) is included. The field is 6 bits long; - C (302a): This field indicates the presence of the contention-free random access resource field. If the value of this field is set to 1, the following fields are present: random access preamble index field, S / U field, SS / PBCH index field, PRACH mask index field, repetition count field, and reserved bits in the same octet. If the value of this field is set to 0, these fields are not present. - S / U: This field indicates which UL carrier is used to transmit PRACH for contention-free random access resources. If the value of this field is set to 1, SUL is used; otherwise, NUL is used. This field is 1 bit long. - Random Access Preamble Index (310b): This field indicates the random access preamble index of a contention-free random access resource. This field should not be set to 0b000000. This field is 6 bits long. - SS / PBCH Index (312b): This field indicates the SS / PBCH that should be used to determine the timing of RACH transmissions for contention-free random access resources. This field is 6 bits long; - PRACH Mask Index (312a): This field indicates the timing of (multiple) RACHs associated with the SS / PBCH indicated by the 'SS / PBCH Index' for PRACH transmissions on contention-free random access resources. It indicates the origin of... rach- ConfigDedicated A subset of the (multiple) RACH timings for the UL carrier (indicated by the S / U field), (if provided, otherwise it indicates) firstActiveUplinkBWP-Id UL BWP configuration from rach-ConfigCommon A subset of the (multiple) RACH timings for the UL carrier (indicated by the S / N field, as specified in TS 38.331[5]). The UE ignores the repetition count field when it is not set to 0. The field is 4 bits long; - Repetition Count (314a): This field indicates the number of Msg1 repetitions applied to contention-free random access. If this field is set to 0, the Msg1 repetition count is not applied. If this field is set to 1, the Msg1 repetition count is 2. If this field is set to 2, the Msg1 repetition count is 4. If this field is set to 3, the Msg1 repetition count is 8. This field is 2 bits long. Note 1: When the LTM target cell is configured with contention-based random access resources, and FeatureCombinationPreambles Having the same Msg1 repetition count and featureCombination Only indicate Msg1 repeats msg1-Repetition At this time, non-zero Msg1 duplicate values ​​can only be included in the LTM cell handover command MAC CE.

[0060] The technical issues to be addressed will be discussed below. Since link adaptation is crucial for achieving good spectral efficiency, it is possible to determine the appropriate modulation and coding rates for the data channel, as well as the aggregation level for the control channel as the physical downlink control channel (PDCCH), based on channel parameters such as CRI, CQI, PMI, RI, also known as CSI acquisition.

[0061] For Rel-19 LTM, it has been agreed that CSI acquisition is based on downlink reference signals (e.g., CSI-RS) for candidate cells, whereby the terminal device or UE (510) can acquire and report CSI parameters for one or more candidate cells (530a to 530n). These parameters are used for transmission and reception in the target cell (530a) after cell handover, thereby reducing the need for additional channel quality information measurements in the target cell (530a) during initial transmission or reception.

[0062] To improve communication quality and avoid the need for the UE (510) to report any channel quality information measurements to one or more network nodes (515), a method for acquiring CSI based on sounding reference signal (SRS) transmission is proposed. This disclosure describes the reception of a cell handover command (514b) to enable SRS-based CSI acquisition for configuration, signaling, and UE procedures of (multiple) mobility candidate cells (530a to 530n).

[0063] This disclosure describes the configuration, signaling, and UE procedures for SRS-based CSI acquisition of (multiple) mobility candidate cells (530a to 530n) after the receipt of a cell handover command (514c). The technical problems to be solved include: (i) SRS transmissions by the UE triggered from the serving cell to the candidate cell; and (2) LTM-SRS transmissions to the target candidate cell triggered by a cell handover command (CSC).

[0064] The proposed solution addresses the aforementioned problem (i.e., reducing the need for additional channel quality information measurements in the target cell (530a) during initial transmission or reception) because the physical uplink scheduling channel (PUSCH) transmission based on SRS, through the proposed signaling, reflects the actual channel quality, thereby enabling higher communication quality (on the uplink, downlink, or both).

[0065] This disclosure proposes a framework (including configuration, signaling, and UE procedures) to enable SRS-based CSI acquisition for one or more mobility candidate cells (530a to 530n) prior to the receipt of a cell handover command (514b).

[0066] In one example embodiment, the UE can be configured to transmit a Sounding Reference Signal (SRS) for PUSCH transmissions associated with an LTM cell handover process: (i) wherein the Sounding Reference Signal (SRS) can be triggered by the serving cell in a cell handover command; (ii) after the cell handover, the SRS is associated with at least one (e.g., first / second, etc.) PUSCH on a candidate target cell; and (iii) wherein the SRS transmission parameters are determined based on information included in the cell handover command. The timing of the SRS transmission is determined by the UE after receiving the cell handover command (if the SRS transmission is triggered), and the PUSCH transmission to the candidate cell after the cell handover command is based on information indicated by the CSC, the SRS transmission, and the DCI for scheduling uplink grants (DCI scheduled by the target cell).

[0067] In one example embodiment, consider the following aspects:

[0068] Firstly, the SRS configuration used for LTM cell handover operations.

[0069] Secondly, LTM SRS triggering is performed by the cell handover command.

[0070] Thirdly, determine the transmission timing, timing advance (TA), and spatial relationships for LTM SRS.

[0071] Fourthly, the PUSCH transmission parameters are determined based on the SRS triggered (and transmitted) by the target cell and the DCI authorized by the UL of the target cell.

[0072] The first aspect relates to SRS configuration for LTM cell handover operations: In an example embodiment, the UE (510) is configured with an SRS configuration (503) associated with LTM cell handover / LTM operations. The SRS configuration (503) may be included in the LTM configuration (502). The SRS configuration for candidate cells may be provided in the LTM configuration (502) as part of the serving cell configuration or cell group configuration of the candidate cells. The SRS configuration may be provided as part of an LTM candidate configuration (candidate configuration IE, information element). In some examples, this configuration may be associated with an LTM (candidate) configuration, which may have common parameters for one or more candidate cells. The LTM candidate configuration may include RRC reconfiguration of the candidate cells. In some examples, the SRS configuration may be part of the serving cell configuration. In another example, the SRS configuration (503) may be part of a common configuration for one or more candidate cell configurations.

[0073] In any of the examples in this article, SRS or LTM-SRS can be used interchangeably.

[0074] In any of the examples in this article, SRS resources (sets) or LTM-SRS resources (sets) can be used interchangeably.

[0075] In any example in this document, SRS or LTM-SRS may refer to the SRS used interchangeably for mobility operations (e.g., L3 handover and / or LTM cell handover).

[0076] In any example in this document, SRS resource(set) or LTM-SRS resource(set) may refer to the SRS resource(set) used interchangeably for mobility operations (e.g., L3 handover and / or LTM cell handover).

[0077] In one example embodiment, the UE (510) can be configured to send an SRS (513b) to one or more candidate cells (530) for LTM cell handover purposes (this may be referred to as LTM-SRS). The SRS configuration may be associated with certain candidate IDs.

[0078] In one example, the SRS configuration can be common to all candidates; that is, the SRS resource set ID can be associated with an LTM transport to one or more candidate cells. For example, outside of any LTM candidate IE, the SRS configuration can be provided as an LTM-Config that is common to all candidate cells.

[0079] In one example, SRS can be configured such that in the target cell, one SRS transmission occurs before the cell handover command, and another SRS transmission occurs after the cell handover command. The SRS configuration before and after CSC can be the same, or they can have separate configurations for SRS characteristics, such as frequency hopping, SRS density, and the number of ports used by the SRS transmission. For example, the SRS configuration to be used before CSC can be given in the LTM configuration outside the candidate cell's RRC configuration (i.e., outside the candidate cell's serving cell configuration or cell group configuration), while the SRS configuration to be used after CSC can be given in the candidate cell's ltm-CandidateConfig (which contains the candidate cell's associated RRCReconfiguration).

[0080] The second aspect involves LTM SRS triggering via cell handover commands.

[0081] In one example, the UE may indicate its ability to support SRS transmissions toward the target cell based on the configuration provided for cell handover, either during or after receiving the cell handover command.

[0082] Alternatively or additionally, the UE may indicate its ability to support SRS transmissions triggered by the CSC. In one example embodiment, the CSC may include one or more fields that trigger / instruct / configure the UE to perform at least one SRS transmission for a candidate cell. In one example, the SRS is transmitted prior to cell handover.

[0083] Figures 4A to 4C Various MAC CE field formats according to some example embodiments of this disclosure are illustrated. Figures 4D to 4E The diagram illustrates the transmission timing of Cell Command Handover (CSC) (402, 412).

[0084] In any example herein, SRS or LTM-SRS may be used interchangeably. In any example herein, SRS or LTM-SRS may refer to the interchangeable SRS used for mobility operations (e.g., L3 handover and / or LTM cell handover). In any example herein, LTM-SRS may refer to SRS transmissions used for mobility operations. LTM-SRS transmissions may refer to SRS transmissions used for mobility purposes during cell handover (from source to at least one target candidate cell), before cell handover, and after cell handover.

[0085] In the example implementation, the fields in the CSC (402, 412) are associated with the LTM SRS (406, 416) configuration and / or an indication that the UE is requested to send LTM SRS. Fields in the CSC may point to an SRS resource set ID configured by the RRC in the LTM configuration / LTM candidate configuration. Fields in the CSC may point to an SRS resource set ID configured in the LTM configuration for a candidate cell ID. In one example, the code point in the CSC may refer to one or more SRS resource IDs (310f) for a specific candidate cell ID.

[0086] In one example, at least one field in the CSC (including the code point or identifier of the reference identifier) ​​may refer to an SRS resource set ID configured for LTM purposes. In one example, the SRS resource set ID may be indicated by a field in the MAC CE that refers to one or more configured SRS resource sets for LTM purposes. The target candidate cell (e.g., 530a) for SRS transmission may be indicated by the CSC, i.e., it may be determined based on the QCL source of the indicated TCI state for the candidate cell.

[0087] In one example embodiment, the CSC (402, 412) may include a field indicating a candidate cell for which the SRS resource set ID (310f) refers to a target candidate cell ID (e.g., target configuration ID) in the CSC that the UE can interpret as a relevant cell for the SRS resource set. In one example embodiment, at least one code point value may indicate that no SRS transmission was triggered by a cell handover command. Figures 4A to 4C A sample format for CSC that includes SRS-related information is described.

[0088] In one example, after receiving the CSC, the UE determines whether the SRS transmission is triggered / indicated by at least one field in the CSC. In one example, the field that triggers the SRS can be indicated by at least one other field S (302a). When S has a first value, S=1 indicates that the field / octet associated with the SRS transmission exists in the cell handover command. When S has a first value, S=1 indicates that the field / octet associated with the SRS transmission contains information indicating the SRS transmission.

[0089] S (302a) has a first value, S=0 indicating that the field / octet associated with the SRS transmission does not exist in the Cell Handover Command (CSC). If the field exists, the UE (510) can apply the indicated SRS Resource Set ID (310f) to the SRS transmission based on the Cell Handover Command. In an example embodiment, the LTM SRS request may be a code point mapping to a configured SRS Resource Set ID for an LTM candidate cell.

[0090] In one example embodiment, this field can be interpreted as a pointer to a configured SRS resource set for LTM (e.g., a configured SRS resource set ID or SRS configuration ID). In one example embodiment, this field can be interpreted as a pointer to a configured SRS resource for LTM candidate target cells. In some examples, this field has a non-zero value, which is a value requested by the SRS request.

[0091] In one example embodiment, the LTM SRS request may be a code point mapping to a configuration SRS resource set ID for an LTM candidate cell. In one example embodiment, this field may be interpreted as a pointer to all configuration SRS resource sets for LTM. In one example embodiment, this field may be interpreted as a pointer to the configuration SRS resource for LTM for the LTM candidate target cell, as indicated by a cell handover command.

[0092] In one example embodiment, the indication given in the above example for triggering / instructing / configuring the UE to perform at least one SRS transmission (402, 412) against a candidate cell (indicated in the CSC) can be provided in the DCI of the scheduling CSC.

[0093] In one example, an SRS request / trigger can be an indication used to trigger an LTM-SRS transmission. This indication can be a 1-bit indication. This indication can instruct the UE to trigger an LTM SRS transmission, where LTM-SRS is specific to the LTM candidate cell indicated by the CSC and any / all LTM candidate cells.

[0094] The indication may have a first value to instruct the UE to transmit LTM-SRS as part of LTM cell handover (i.e., before, after, or during LTM cell handover). The indication may have a second value to instruct the UE not to transmit LTM-SRS as part of LTM cell handover (i.e., before, after, or during LTM cell handover).

[0095] In one example embodiment, the timing advance (TA) value supplied in the CSC can be based on the SRS transmission performed by the UE.

[0096] The third aspect involves determining the transmission timing (TA) and spatial relationships for LTM SRS. In one example embodiment, the determination of LTM-SRS spatial relationships is as follows: the spatial relationship configuration for LTM-SRS can be determined based on one of the candidate TCI states indicated among the candidate cells(s) in the cell handover command. For example, this can be based on the joint / DL TCI state or UL TCI state given in the cell handover command (where TCI states are given separately for DL ​​and UL). For example, a reference signal (RS) of type QCL configured as 'typeD' in the indicated TCI state can be used to determine the spatial relationship information for SRS. Power control parameters for LTM SRS (e.g., Po value, alpha value, one or more of the downlink path loss estimates) can be determined based on one of the indicated TCI states.

[0097] In one example embodiment, the timing of LTM SRS transmission is determined as follows:

[0098] Figure 4D and Figure 4E An example is shown where the SRS transmission timing is determined by the slot offset K configuration provided in the SRS configuration.

[0099] In one example embodiment, the timing of the LTM SRS transmission is determined by the UE as at least one time slot (slot n) prior to the transmission of the first UL transmission to the target cell (530a). In another example embodiment, the timing of the LTM SRS transmission is determined by the UE as at least one time slot prior to the transmission of the RRC reconfiguration completion message to the target cell (e.g., transmitted during RACH-free cell handover using CG or RACH-free or RACH-based cell handover using DG).

[0100] In one example embodiment, the timing of LTM SRS transmission is determined by the UE as at least one slot / symbol before receiving the first DL message from the target cell (e.g., before monitoring DCI for a RACH-free cell handover based on dynamic grant).

[0101] In one example embodiment, if the first UL transmission following the cell handover command occurs before the time slot offset K, the UE can send the first UL transmission before the SRS transmission of the SRS. The UE can send (multiple) SRS transmissions after the first UL transmission.

[0102] In one example embodiment, the LTM-SRS transmission applies the TA value for signaling notification in the cell handover command. In one example embodiment, the UE may indicate in the first UL transmission (e.g., in the case of RACH-based LTM, RRC reconfiguration complete or message 3) whether the UE has performed an SRS transmission to the target.

[0103] The fourth aspect involves determining PUSCH transmission parameters based on the SRS triggered (and sent) by the cell handover command and the DCI authorized by the target cell scheduling UL.

[0104] In one example embodiment, the DCI sent by the target candidate cell includes the field LTM-SRI (SRS Resource Indicator), which refers to the SRS transmission from the UE to the candidate cell triggered by the cell handover command.

[0105] In one example embodiment, the LTM-SRI field refers to the latest SRS transmission from the UE to the candidate cell triggered by the cell handover command.

[0106] In one example embodiment, the LTM-SRI field refers to the latest SRS transmission from the UE to the candidate cell triggered by the cell handover command.

[0107] In one example embodiment, the DCI for scheduling PUSCH transmissions based on SRS transmissions may include a field indicating whether the SRI field indicates LTM-SRS or serving cell SRS resources. If the field indicates LTM-SRS resources, the UE interprets the SRI as an indicator of the SRS resources associated with the transmitted LTM-SRS resource set.

[0108] If the field indicates a serving cell SRS resource, the UE interprets the SRI as an indicator of the SRS resource associated with the transmitted (serving cell) SRS resource set. In one example embodiment, the PUSCH transmission to the target candidate cell can be dynamically authorized. The UE applies the PUSCH parameters indicated by the DCI and determines that the SRI refers to an LTM SRS transmission triggered by the CSC.

[0109] In one example, the UE application uses the SRI, TPMI-RI, and MCS of the dynamic authorization indication to determine that these fields refer to the LTM SRS transmission prior to the cell handover to the candidate cell (Option 1).

[0110] In one example, the UE application uses the SRI, TPMI-RI, and MCS of the dynamic authorization indication to determine that these fields refer to the LTM SRS transmission (e.g., 552) after the cell handover (option 2) to the aforementioned candidate cell (or target cell 530a).

[0111] In one example, the target cell's DCI (530a) can instruct the UE whether to apply the provided parameters to the PUSCH transmission based on the LTM SRS (or other SRS).

[0112] In one example, the target cell's DCI can instruct the UE whether to apply the provided DCI parameters to the PUSCH transmission.

[0113] The field in the DCI indicates whether the UE applies the SRI associated with the SRS triggered by the cell handover command to the scheduled PUSCH transmission.

[0114] In one example embodiment, the UE determines that the SRI field in the DCI scheduled by the target cell (current serving cell) refers to the (latest) LTM SRS transmission of the indicated SRI. This occurs before or during cell handover.

[0115] In one example embodiment, the UE determines that the SRI field in the DCI scheduled by the target cell (current serving cell) refers to the (latest) LTM SRS transmission of the indicated SRI until a new SRS is sent.

[0116] Figure 4D , Figure 4EThe proposed LTM-SRS transmission process and related PUSCH transmission are described in the paper.

[0117] In one example embodiment, the timing of LTM-SRS transmission triggered by the cell handover command is determined as follows:

[0118] Option 1: Before the transmission of the first uplink message (i.e., RRCreconfigcomplete).

[0119] Option 2: (First) Timing, after the transmission of the first uplink message.

[0120] These can be configurable options or defined in the specification, so there are two different options. The advantage of option 1 is that we can use a higher MCS from the first UL transmission, and the advantage of option 2 is that the downtime can be shorter, but at the cost of not being able to use a higher MCS before sending LTM SRS immediately after cell handover.

[0121] Figure 5A and Figure 5B Figure 5 depicts a cell handover environment according to some example embodiments of the present disclosure. The cell handover environment (500) may include at least a terminal device (510) communicating with at least one network node (515a to 515n), which may serve both a cell (520) and one or more candidate cells (530a to 530n). The one or more candidate cells (530a to 530n) may include at least a target cell (530a) and other candidate cells (530b to 530n). In one example, both the serving cell (520) and the target cell (530a) may be served by the same network node (515a) (see [link to documentation]). Figure 4A Alternatively, it can be served by different individual network nodes (515b) (see [link]). Figure 4B For the purposes of discussion, at least one network node (515a to 515n) may be collectively referred to as at least one network node (515).

[0122] Figure 5A and Figure 5BSimplified block diagrams of a terminal device (510) and a network node (515) suitable for implementing exemplary embodiments of the present disclosure are also disclosed. The terminal device (510) may include one or more processors (531), one or more memories (532) coupled to the one or more processors (531), and the one or more processors (531) may be coupled to a transceiver communication module (533) including at least one antenna for bidirectional communication. The network node (515) may include one or more processors (534), one or more memories (535) coupled to the one or more processors (534), and the one or more processors (531) may be coupled to the transceiver communication module (533) including at least one antenna for bidirectional communication.

[0123] The processor (531) can be of any type suitable for a local technology network, and by way of non-limiting example, can include one or more of the following: a general-purpose computer, a special-purpose computer, a microprocessor, a digital signal processor (DSP), and a processor based on a multi-core processor architecture. The device (510) can have multiple processors, such as application-specific integrated circuit chips that are time-dependent on a clock synchronized with the main processor.

[0124] The memory (532) may include one or more non-volatile memories and one or more volatile memories. Examples of non-volatile memories include, but are not limited to, read-only memory (ROM), electrically programmable read-only memory (EPROM), flash memory, hard disk, compact disc (CD), digital video disc (DVD), optical disc, laser disc, and other magnetic and / or optical storage devices. Examples of volatile memories include, but are not limited to, random access memory (RAM) and other volatile memories that do not persist during power outages.

[0125] A computer program may include computer-executable instructions that are executed by an associated processor (531). The instructions of the program may include instructions for performing operations / actions of some example embodiments of this disclosure. The program may be stored in memory, such as ROM (532). The processor (531) may perform any suitable actions and processes by loading the program into RAM.

[0126] The exemplary embodiments of this disclosure can be implemented by a program, enabling the terminal device (510) to execute the commands shown in FIG4 to... Figure 5C Any process discussed in this disclosure. Exemplary embodiments of this disclosure may also be implemented using hardware or a combination of software and hardware.

[0127] In some example embodiments, the program may be tangibly contained in a computer-readable medium, which may be included in a terminal device (510) (such as in a memory (532)) or in another storage device accessible by the terminal device (510). The terminal device (510) may load the program from the computer-readable medium into RAM for execution. In some example embodiments, the computer-readable medium may include any type of non-transitory storage medium, such as ROM, EPROM, flash memory, hard disk, CD, DVD, etc. The term “non-transitory” as used herein is a limitation on the medium itself (i.e., tangible, not tactile), rather than a limitation on the persistence of data storage (e.g., RAM and ROM).

[0128] Generally, the various embodiments of this disclosure can be implemented in hardware or dedicated circuitry, software, logic, or any combination thereof. Some aspects can be implemented in hardware, and others can be implemented using firmware or software that can be executed by a controller, microprocessor, or other computing device. Although various aspects of the embodiments of this disclosure are illustrated and described as block diagrams, flowcharts, or using some other graphical representation, it should be understood that, as non-limiting examples, the blocks, apparatuses, systems, techniques, or methods described herein can be implemented using hardware, software, firmware, dedicated circuitry or logic, general-purpose hardware or controllers or other computing devices, or some combination thereof.

[0129] Some exemplary embodiments of this disclosure also provide at least one computer program product tangibly stored on a computer-readable medium, such as a non-transitory computer-readable medium. The computer program product includes computer-executable instructions, such as instructions included in a program module, which execute in a device on a target physical or virtual processor to perform any of the methods described above. Typically, a program module includes routines, programs, libraries, objects, classes, components, data structures, etc., that perform a particular task or implement a particular abstract data type. In various embodiments, the functionality of a program module can be combined or split among program modules as needed. The machine-executable instructions of a program module can execute within a local or distributed device. In a distributed device, a program module can reside on both local and remote storage media.

[0130] Program code used to perform the methods of this disclosure may be written in any combination of one or more programming languages. This program code may be provided to a processor or controller of a general-purpose computer, special-purpose computer, or other programmable data processing apparatus, such that, when executed by the processor or controller, the program code causes the functions / operations specified in the flowcharts and / or block diagrams to be implemented. The program code may be executed entirely on a machine, partially on a machine, as a stand-alone software package, partially on a machine and partially on a remote machine, or entirely on a remote machine or server.

[0131] In the context of this disclosure, computer program code or related data may be carried by any suitable carrier to enable a device, apparatus, or processor to perform the various processes and operations described above. Examples of carriers include signals, computer-readable media, etc.

[0132] Computer-readable media can be computer-readable signal media or computer-readable storage media. Computer-readable media can include, but is not limited to, electronic, magnetic, optical, electromagnetic, infrared, or semiconductor systems, apparatuses, or devices, or any suitable combination of the foregoing. More specific examples of computer-readable storage media will include electrical connections having one or more wires, portable computer floppy disks, hard disks, random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM or flash memory), optical fibers, portable optical disc read-only memory (CD-ROM), optical storage devices, magnetic storage devices, or any suitable combination of the foregoing.

[0133] The proposed LTM-SRS transmission process illustrates various aspects of the solution disclosed in the flowchart of Figure 5, which shows examples of methods according to some embodiments of this disclosure. For the purposes of discussion, the method in Figure 5 will be described primarily from the perspective of the terminal device (510).

[0134] Figure 5C Some advantages of the solution implemented in this way include: (a) SRS-based PUSCH transmission enables higher communication quality after cell handover; (b) the method enables the network to indicate PUSCH parameters that reflect the actual channel quality; and (c) the network can avoid using conservative MCS / layer numbers for scheduling.

[0135] The various aspects of this method can be found Figure 5C The steps executed by the UE in the signal flow diagram are discussed.

[0136] The first aspect of the method relates to the configuration of the probe reference signal (SRS) for LTM cell handover operations.

[0137] The SRS configuration (503) may be included in the LTM configuration (502a). In some examples, the SRS configuration may be configured for mobility operations (i.e., for either or both of L3 / RRC level mobility or LTM). The SRS configuration for a candidate cell (any of 530a to 530n) may be provided in the LTM configuration (502a) as part of the serving cell configuration or cell group configuration of the candidate cell. The SRS configuration may be provided as part of an LTM candidate configuration (candidate configuration IE, information element). In some examples, this configuration may be associated with an LTM (candidate) configuration that may have common parameters for one or more candidate cells. The LTM candidate configuration may include the RRC reconfiguration of the candidate cell. In some examples, the SRS configuration may be part of the serving cell configuration. In another example, the SRS configuration (503) may be part of a common configuration for one or more candidate cell configurations.

[0138] In any of the examples in this article, SRS or LTM-SRS can be used interchangeably.

[0139] In any of the examples in this article, SRS resources (sets) or LTM-SRS resources (sets) can be used interchangeably.

[0140] In any example in this document, SRS or LTM-SRS can refer to the interchangeable SRS used for mobility operations (e.g., L3 handover and / or LTM cell handover).

[0141] In any example in this document, SRS resource(set) or LTM-SRS resource(set) can refer to interchangeably used SRS resource(set) for mobility operations (e.g., L3 handover and / or LTM cell handover).

[0142] In one example embodiment, the UE can be configured to send SRS to one or more candidate cells for LTM cell handover purposes (this may be referred to as LTM-SRS (513b)).

[0143] SRS configurations can be associated with certain candidate IDs.

[0144] In one example, the SRS configuration (503a) can be common to all candidates, meaning that the SRS resource set ID can be associated with an LTM transport to one or more candidate cells. For example, outside of any LTM candidate IE, the SRS configuration can be provided as an LTM-Config that is common to all candidate cells (530a to 530n).

[0145] In one example, SRS can be configured such that in the target cell (530a), one SRS transmission occurs before the cell handover command, while another SRS transmission (584, 594) occurs after the cell handover command (514c, 578). The SRS configuration (503) before and after the CSC (514c) can be the same, or they can have separate configurations for SRS characteristics, such as frequency hopping, SRS density, number of ports used by the SRS transmission, etc. For example, the SRS configuration to be used before the CSC can be given in the LTM configuration outside the candidate cell's RRC configuration (i.e., outside the candidate cell's serving cell configuration or cell group configuration), while the SRS configuration to be used after the CSC can be given in the candidate cell's ltm-CandidateConfig (which contains the candidate cell's associated RRCReconfiguration).

[0146] Referring to Figure 5, in step 502, the UE (510) may be configured with an SRS configuration (503) associated with LTM cell handover / LTM operation. In some examples, the SRS configuration may be configured for mobility operations (i.e., for either or both of L3 / RRC level mobility or LTM). More specifically, the SRS configuration (503) may be included in the LTM configuration (502a). In one example, the SRS configuration (503) for a candidate cell (one of 530a to 530n) may be provided in the LTM configuration (502a) as part of the serving cell configuration.

[0147] The SRS configuration can be provided as part of an LTM-candidate IE. In some examples, this configuration can be associated with an LTM (candidate) configuration, which may have common parameters for one or more candidate cells but is signaled in another information element. In another example, the SRS configuration (503) can be part of the serving cell (520) configuration. In yet another example, the SRS configuration (503) can be part of a common configuration for one or more candidate cell configurations.

[0148] In any example herein, SRS or LTM-SRS may be used interchangeably. In any example herein, SRS or LTM-SRS may refer to the SRS used interchangeably for mobility operations (e.g., L3 handover and / or LTM cell handover). In any example herein, LTM-SRS may refer to SRS transmissions used for mobility operations. LTM-SRS transmissions may refer to SRS transmissions used for mobility purposes during, before, and after cell handover (from source to at least one target candidate cell).

[0149] In step 504, the UE (510) may perform measurements and reports on at least one of the serving cell (520) and one or more candidate cells (530a to 530b).

[0150] In step 506, the UE (510) can receive candidate TCI state activation (511b) from the network node (515).

[0151] In step 538, the UE (510) may perform a timing advance (TA) acquisition for at least one candidate cell (e.g., 530a, 530b, etc.).

[0152] In step 540, the UE (510) may receive a cell handover command (514b), which includes an LTM-SRS trigger (509b). In step 542, the UE (510) may determine, based on the cell handover command (CSC) (514b), to hand over to a target candidate cell (530a). In step 548, the UE (510) may determine the spatial relationship (548a) and the indicated TCI state. In any example, the TCI state information (548b) signaled in the cell handover command may activate or indicate at least one TCI state (548b) (e.g., a combined TCI state for uplink and downlink, or a separate TCI state for uplink and downlink). In some examples, the activation and indication of at least one TCI state may be used interchangeably. The cell handover command may activate at least one TCI state or indicate at least one TCI state (which may have been activated earlier). In step 550, the UE (510) can determine the timing of the transmission for sending LTM-SRS (513b).

[0153] The UE may perform the steps in option 1 (551), which includes performing step 552, whereby the UE may send a cell handover command (514b) to one or more candidate cells (530) or target cells (530a) based on the determination of one or more parameters in the cell handover command (CSC) (514b).

[0154] In step 554, the UE may receive downlink control information (DCI) that schedules uplink (UL) grants for UL transmission. In one example, the DCI may include information relating to the transmitted LTM-SRS (513b). In step 556, the UE (510) may determine transmission parameters for the PUSCH (555) message (first UL message) based on the indications in the LTM-SRS (513b) and the DCI (554a). In step 558, the UE may transmit the PUSCH message (555) to the target cell (530a) according to the transmission parameters in the LTM-SRS.

[0155] Alternatively, the UE may perform the steps in Option 2, which include step 562, whereby the UE may determine a first transmission timing and parameters (562a) for the PUSCH (563) (first UL message) based on the indication (556b) in the LTM-SRS and the first DCI (560a). In step 564, the UE may send the PUSCH (first UL message) (563) according to the first transmission timing and parameters (562a). In one example, the first PUSCH message (563) may be a (RRCreconfiguration_complete) message scheduled to the target cell (530a) by the DCI.

[0156] In step 566, the UE may transmit LTM-SRS (513b) to one or more candidate cells (530) or a target cell (530a) based on the determined first transmission timing and parameters (562a). In step 568, the UE may receive a second DCI (568a) from the target cell (530a) or from one or more candidate cells (530), which schedules a second uplink grant (568b) for a second UL transmission (570), wherein the second DCI (568a) may include information (562) relating to the transmitted LTM-SRS.

[0157] In step 570, the UE may send a second PUSCH (second UL message (569)) to the target cell (530a) according to the second transmission timing parameter (570a) indicated by the second DCI (568a) and the LTR-SRS (513b) (568c) to complete the procedure. In one example, the second (additional) PUSCH message (570a) may be based on the indications in the LTM-SRS (513b) and DCI (568a).

[0158] The second aspect of the method involves LTM SRS triggering by the target cell DCI. In one example embodiment, the DCI format for triggering an SRS transmission to the target cell (530a) may include one or more fields associated with the LTM-SRS transmission or triggering the LTM-SRS transmission. As an example, the DCI format may be a format used for scheduling UL transmissions (e.g., PUSCH transmissions (558, 564, 570)).

[0159] In one example embodiment, fields in the DCI (554a, 568a) can be associated with an LTM SRS configuration. Fields in the DCI can point to an SRS resource set ID configured for mobility purposes. The SRS resource set ID configured for mobility purposes can be provided by the RRC in the LTM configuration / LTM candidate configuration. In one example, a DCI field (code point) can refer to one or more SRS resource set IDs for a specific candidate cell ID used for LTM purposes. In one example, a DCI field (code point) can refer to an SRS resource set ID configured for LTM purposes. In one example embodiment, the DCI may include fields indicating whether the SRS resource set ID refers to an LTM configuration or a serving cell configuration. In one example, one or more SRS resource sets or one or more SRS resources can be candidate cell specific. SRS resource sets used for mobility purposes can be referenced using fields / information in the DCI. A DCI referencing an SRS can be sent by the target candidate cell. The DCI can indicate the triggering of an SRS transmission or reference an earlier transmitted SRS.

[0160] In some examples, the DCI may include a field indicating how to interpret SRS-related information included in the DCI. When this field is set to a first value, it can indicate the serving cell configuration (i.e., the SRS associated with the serving cell). In one example, the UE interprets the SRS-related information to point to at least one SRS resource set ID in the serving cell configuration. When this field is set to a second value, the SRS-related information is mapped to an SRS resource set ID given in the LTM configuration. Fields in the DCI may point to an SRS resource set ID configured by the RRC in the LTM configuration / LTM candidate configuration. The SRS resource set ID may be associated with a candidate cell. SRS-related information may be provided in the form of code points.

[0161] The associated candidate cell for SRS transmission can be determined based on at least one of the following: the candidate cell ID based on the field that triggers SRS in the DCI, the active TCI state in the CSC, or the candidate identifier signaled in the cell handover command. The UE can determine the candidate cell ID based on the CSC (514c). In one example, the DCI may include a field indicating the candidate cell identifier. The candidate cell identifier indicates the target / candidate cell for SRS transmission. The candidate cell ID can be used to determine the spatial relationship for SRS transmission; that is, the UE can determine the spatial relationship based on the indicated / active TCI state for the candidate cell. In some examples, if the target cell is scheduled for triggering LTM SRS transmission, the candidate ID field or a field referencing the candidate ID is set to the candidate cell ID, or the candidate ID is implicitly determined based on the candidate cell handover scheduling DCI.

[0162] In one example, the UE may indicate its ability to support SRS transmissions toward the target cell (transmissions performed after receiving a cell handover command). In another example, the UE may indicate its ability to support PUSCH transmissions based on SRS transmissions toward the target cell (transmissions performed after receiving a cell handover command).

[0163] Alternatively or otherwise, the UE may indicate its ability to support LTM-SRS transmissions triggered by DCI.

[0164] The third aspect of this method relates to the timing advance (TA) value for LTM-SRS. In one example embodiment, the spatial relationship configuration for LTM-SRS can be determined based on the (candidate) TCI state indicated in the cell handover command.

[0165] In one example, if a separate TCI state is indicated, the UE applies the UL TCI state as the spatial relationship. In another example, if a combined TCI state is indicated, the UE applies the DL (or combined) TCI state as the spatial relationship. In yet another example, the DCI is triggered by LTM SRS scheduling.

[0166] The fourth aspect of this method relates to spatial relationships for LTM-SRS. In one example embodiment, the spatial relationship configuration for LTM-SRS can be determined based on the candidate TCI state indicated in the cell handover command. In one example, if a single TCI state is indicated, the UE applies the UL TCI state as the spatial relationship. In another example, if a combined TCI state is indicated, the UE applies the DL (or combined) TCI state as the spatial relationship.

[0167] In one example embodiment, the spatial relationships for LTM-SRS transmission can be determined based on the DCI triggered for LTM-SRS scheduling. Quasi-colocation information can be determined based on the DCI (e.g., determining the reference signal used as the QCL source for DCI transmission), and the QCL information RS is applied as the spatial relationships for LTM-SRS.

[0168] In any embodiment herein, spatial relation may refer to using a determined downlink reference signal as a reference for uplink transmission. In some examples, spatial relation RS may refer to the spatial relationship between a reference RS and a target SRS. The reference RS may be an SSB / CSI-RS or an SRS.

[0169] The fifth aspect of this method relates to the power control configuration for LTM-SRS.

[0170] In one example embodiment, the power control parameters for LTM SRS can be determined based on the indicated TCI state, such as one or more of the Po value, alpha value, and downlink path loss estimate. In another example embodiment, the power control parameters for LTM SRS (e.g., one or more of the Po value, alpha value, and downlink path loss estimate) can be determined based on the reference signal or quasi-parallel source RS included in the indicated TCI state. In one instance, the power control parameters are provided as multiple information elements in the DCI that triggers LTM-SRS. In another example, the power control parameters are provided in the TCI state provided in the DCI that triggers LTM-SRS. In yet another example, the power control parameters are provided via higher-layer signaling prior to the cell handover command that the UE will apply in the target cell.

[0171] The sixth aspect of the method relates to PUSCH transmissions based on LTM-SRS transmissions scheduled by the DCI. In one example embodiment, the DCI transmitted by the target candidate cell includes the field LTM-SRI (SRS Resource Indicator), which indicates an SRS transmission by the UE to the candidate cell triggered by the DCI transmitted by the candidate cell. In one example embodiment, the LTM-SRI field indicates the latest SRS transmission by the UE to the candidate cell, triggered by the DCI transmitted by the candidate cell. In one example embodiment, the LTM-SRI field indicates a transmission of an SRS resource within the LTM-SRS resource set. In one example embodiment, the LTM-SRI field indicates the latest transmission of an SRS resource (ID) within the LTM SRS resource set.

[0172] In one example embodiment, the DCI that schedules PUSCH transmissions based on SRS transmissions may include a field indicating whether the SRI field indicates LTM-SRS or serving cell SRS resources.

[0173] If the field indicates an LTM-SRS resource, the UE interprets the SRI as an indicator of the SRS resource associated with the LTM-SRS resource set being transmitted.

[0174] If the field indicates serving cell SRS resources, the UE interprets the SRI as an indicator of the SRS resources associated with the transmitted (serving cell) SRS resource set. In one example embodiment, the SRI (SRS Resource Indicator) field in the DCI refers to the latest SRS transmission made by the UE to the candidate cell.

[0175] If the latest transmission is LTM-SRS, then SRI refers to the most recently transmitted SRS associated with the LTM-SRS configuration. If the latest transmission is SRS (Serving Cell Configuration SRS), then SRI refers to the most recently transmitted SRS associated with the LTM-SRS configuration.

[0176] As an example, LTM SRS and SRS share the same SRI field.

[0177] In one example, PUSCH transmissions to candidate cells based on LTM-SRS can be scheduled using a dedicated DCI format. By receiving a DCI format specifically designed for LTM-related / mobility-related scheduling, the UE can interpret one or more fields in the DCI as being associated with mobility operations (associated with the target cell).

[0178] In one example, PUSCH transfers to the target candidate cell can be performed on dynamically authorized UL resources.

[0179] In one example embodiment, the UE applies the PUSCH parameter indicated by the DCI and determines that the SRI (SRI information in the DCI) refers to an SRS transmission triggered by the target cell DCI.

[0180] In one example, the applied PUSCH parameters may include one or more of the (LTM-)SRI, TPMI-RI, and MCS indicated by the target candidate cell DCI authorized by the scheduling uplink. The UE may also determine, based on the DCI sent by the target cell, that one or more fields refer to the LTM-SRS sent to the target candidate cell.

[0181] In one example, the target cell's DCI can instruct the UE whether to apply the provided parameters to the PUSCH transmission based on the LTM SRS (or other SRS, such as the serving cell-triggered SRS).

[0182] In one example embodiment, the UE determines that the SRI field in the DCI scheduled by the target cell (which becomes the new serving cell) is a (latest) LTM SRS resource transmission pointing to the target cell.

[0183] In one example embodiment, the UE determines that the SRI field in the DCI scheduled by the target cell (current serving cell) refers to the (latest) LTM SRS resource transmission to the target cell until a new SRS is sent.

[0184] In an example of a terminal device (510) for communication, the terminal device includes: at least one processor (531); and at least one memory (532) storing instructions that, when executed by the at least one processor (531), cause the terminal device (510) to at least: receive (502) a configuration from one or more network nodes (515), the configuration including at least a configuration (503) for transmitting (552) a probe reference signal (513b), the probe reference signal (513b) (5) is used for mobility operations between the serving cell (520) and one or more candidate cells (530); after receiving (540) a cell handover command (514b) from one or more network nodes (515), (566) a probe reference signal (513b) is sent toward one or more candidate cells (530) based on a trigger (509b) for sending (566) a probe reference signal (513b), which is received after the transmission (564) of at least one first uplink message (563).

[0185] In an example of a terminal device (510) used for communication, at least one of the following is performed in conjunction with the terminal device (510): the serving cell (520) and one or more candidate cells (530) are served by the same or different network nodes among one or more network nodes (515); and mobility operations include the terminal device (510) switching from the serving cell (520) to a target cell (530a), the target cell being one of the candidate cells (530).

[0186] In the example of the terminal device (510), the terminal device (510) is further configured to perform at least one of the following: before cell handover, receiving (506) a candidate transmission configuration indication (TCI) status activation (511b) for one or more candidate cells in a cell handover command (514b); and after receiving an uplink grant (554b) for a transmission (566) for scheduling at least one first uplink message (555), sending (564) a probe reference signal (513b).

[0187] In the example of terminal device (510), terminal device (510) is further configured to perform one or more of the following on the target cell (530a) indicated in the cell handover command (514b): determine (542) to hand over to the target cell (530a) based on the cell handover command (514b); determine (546) one or more parameters (546a) required to transmit (552) a probe reference signal (513b) based on the cell handover command (514b); and determine (548) the spatial relationship (548a) for the transmission of the probe reference signal (513b) based on at least one of the following: the Transmission Configuration Indicator Candidate Transmission Configuration Indicator (TCI) state is activated before the cell handover or when the cell handover command (548b) is received; and determine (550) the transmission timing (550a) for the transmission of the probe reference signal (513b).

[0188] In the example of terminal device (510), the terminal device is configured to receive (560) first downlink control information (DCI) (560a) from target cell (530a), the first DCI (560a) being used to schedule a first uplink grant (560b) for sending (564) at least one first uplink message (563) toward target cell (530a).

[0189] In the example of terminal device (510), the terminal device (510) is triggered to send (566) probe reference signal (513b) toward target cell (530a) based on at least one or two of the following: determination (562) of the first transmission timing and parameters (562a) of at least one first uplink message (563); or determination (562) of the first indication (556b) included in the first downlink control information (DCI) (560a) received from target cell (530a).

[0190] In the example of terminal device (510), wherein: terminal device (510) is configured to: send a probe reference signal (513b) toward target cell (530a) when terminal device (510) has been scheduled to send (564) at least one first uplink message (563) to target cell (530a) or has sent (564) at least one first uplink message (563) to target cell (530a); and the timing (564, 566) of transmitting the probe reference signal (513b) is based on the at least one first uplink message (563) sent.

[0191] In the example of terminal device (510), the terminal device (510) is further configured to receive (568) second downlink control information (DCI) (568a) and second uplink grant (568b) from the target cell (530a) for scheduling at least one second uplink message (569) to the target cell (530a) for transmission (570).

[0192] In an example of a terminal device (510) for communication, the transmission of at least one second uplink message (569) by the terminal device (520) is based on one or both of the following: a second transmission parameter (570a) indicated by a second downlink control information (DCI) (568a); and a probe reference signal (513b).

[0193] In an example of a terminal device (510) for communication, at least one second uplink message (569) includes at least one second physical uplink shared channel (PUSCH) message.

[0194] In an example of a terminal device (510) for communication, the terminal device (510) includes: a component for receiving (502) a configuration from one or more network nodes (515), the configuration including at least a configuration (503) for transmitting a probe reference signal (513b) for mobility operations between a serving cell (520) and one or more candidate cells (530); and a component for transmitting (566) a probe reference signal (513b) toward one or more candidate cells (530) based on a trigger (509b) for transmitting (566) the probe reference signal (513b) after receiving (540) a cell handover command (514b) from one or more network nodes (515), the probe reference signal (513b) being received after the transmission (564) of at least one first uplink message (563).

[0195] In an example of a method for communication, the method includes: receiving (502) a configuration by a terminal device (510) from one or more network nodes (515), the configuration including at least a configuration (503) for transmitting a probe reference signal (513b) for mobility operations between a serving cell (520) and one or more candidate cells (530); and, after receiving (540) a cell handover command (514b) from one or more network nodes (515), transmitting (566) a probe reference signal (513b) toward one or more candidate cells (530) based on a trigger (509b) for transmitting (566) the probe reference signal (513b), the probe reference signal (513b) being received after the transmission (564) of at least one first uplink message (563).

[0196] In an example of a terminal device (510), a computer-readable medium includes instructions stored thereon for causing the terminal device (510) for wireless communication to at least perform the methods of the terminal device (510).

[0197] Furthermore, although operations are described in a specific order, this should not be construed as requiring the operations to be performed in the specific order shown or sequentially, or to perform all of the shown operations to obtain the desired result. In some cases, multitasking and parallel processing may be advantageous. Similarly, while several specific implementation details are included in the foregoing discussion, these should not be construed as limiting the scope of this disclosure, but rather as descriptions of features that may be specific to particular embodiments. Unless explicitly stated otherwise, certain features described in the context of a single embodiment may also be implemented in combination in a single embodiment. Conversely, unless explicitly stated otherwise, various features described in the context of a single embodiment may also be implemented individually or in any suitable sub-combination in multiple embodiments.

[0198] Although this disclosure has been described in language specific to structural features and / or methodological actions, it should be understood that the disclosure as defined in the appended claims is not necessarily limited to the specific features or actions described above. Rather, the specific features or actions described above are disclosed as exemplary forms of implementing the claims.

Claims

1. A terminal device (510) for communication, comprising: At least one processor (531); as well as At least one memory (532) stores instructions that, when executed by the at least one processor (531), cause the terminal device (510) to at least: Receive (502) configuration from one or more network nodes (515), the configuration including at least configuration (503) for transmitting a probe reference signal (513b) for mobility operations between the serving cell (520) and one or more candidate cells (530); After receiving (540) a cell handover command (514b) from the one or more network nodes (515), the probe reference signal (513b) is sent (566) toward the one or more candidate cells (530) based on a trigger (509b) for sending (566) the probe reference signal (513b), which is received after the transmission (564) of at least one first uplink message (563).

2. The terminal device (510) according to claim 1, wherein at least one of the following is operated in conjunction with the terminal device (510): The serving cell (520) and the one or more candidate cells (530) are served by the same or different network nodes among the one or more network nodes (515); and The mobility operation includes the terminal device (510) switching from the serving cell (520) to a target cell (530a), the target cell being one of the one or more candidate cells (530).

3. The terminal device (510) according to claim 1, wherein the terminal device (510) is further configured to perform at least one of the following: Before cell handover, a candidate transmission configuration indication (TCI) state activation for the one or more candidate cells is received (506) in the cell handover command (514b). After receiving the uplink grant (554b) for the transmission (566) for scheduling at least one first uplink message (555), the probe reference signal (513b) is sent (564).

4. The terminal device (510) according to claim 2, wherein the terminal device (520) is further configured to perform one or more of the following on the target cell (530a) indicated in the cell handover command (514b): Based on the cell handover command (514b), determine (542) to hand over to the target cell (530a); Determine (546) one or more parameters (546a) required to send (552) the probe reference signal (513b) based on the cell handover command (514b); and The spatial relationship (548a) for the transmission of the probe reference signal (513b) is determined (548) based on at least one of the following: The transmission configuration indication candidate transmission configuration indication TCI state is activated before cell handover or when the cell handover command (548b) is received; and Determine (550) the transmission timing (550a) for the transmission of the detection reference signal (513b).

5. The terminal device (510) according to claim 4, wherein the terminal device (510) is configured to: receive (560) a first downlink control information (DCI) (560a) from the target cell (530a), the first DCI (560a) being used to schedule a first uplink grant (560b) for sending (564) at least one first uplink message (563) toward the target cell (530a).

6. The terminal device (510) according to claim 5, wherein the terminal device (510) is triggered to send (566) the detection reference signal (513b) toward the target cell (530a) based on at least one or both of the following: The determination (562) of the first transmission timing and parameters (562a) of at least one first uplink message (563); or Determination (562) of the first indication (556b) included in the first downlink control information (DCI) (560a) received from the target cell (530a).

7. The terminal device (510) according to claim 5, wherein: The terminal device (510) is configured to send the probe reference signal (513b) toward the target cell (530a) when the terminal device (510) has been scheduled to send (564) the at least one first uplink message (563) to the target cell (530a) or has sent (564) the at least one first uplink message (563) to the target cell (530a). The transmission timing (564, 566) of the probe reference signal (513b) is based on the transmission of the at least one first uplink message (563).

8. The terminal device (510) according to claim 5, wherein the terminal device (510) is further configured to: receive (568) second downlink control information DCI (568a) and second uplink grant (568b) from the target cell (530a) for scheduling at least one second uplink message (569) to the transmission (570) to the target cell (530a).

9. The terminal device (510) according to claim 8, wherein the transmission of the at least one second uplink message (569) by the terminal device (520) is based on one or both of the following: The second transmission parameters (570a) indicated by the second downlink control information DCI (568a); and The detection reference signal (513b).

10. The terminal device (510) according to claim 9, wherein the at least one second uplink message (569) includes at least one second physical uplink shared channel (PUSCH) message.

11. A terminal device (510) for communication, comprising: Components for receiving (502) a configuration from one or more network nodes (515), the configuration including at least a configuration (503) for transmitting a probe reference signal (513b) for mobility operations between the serving cell (520) and one or more candidate cells (530); A component for sending (566) the probe reference signal (513b) toward the one or more candidate cells (530) based on a trigger (509b) for sending (566) the probe reference signal (513b) after receiving (540) a cell handover command (514b) from the one or more network nodes (515), the probe reference signal (513b) being received after the transmission (564) of at least one first uplink message (563).

12. A method for communication, comprising: The terminal device (510) receives (502) a configuration from one or more network nodes (515), the configuration including at least a configuration (503) for transmitting a probe reference signal (513b) for mobility operations between the serving cell (520) and one or more candidate cells (530); After receiving (540) a cell handover command (514b) from one or more network nodes (515), the terminal device (510) sends (566) the probe reference signal (513b) toward one or more candidate cells (530) based on a trigger (509b) for sending (566) the probe reference signal (513b), which is received after the transmission (564) of at least one first uplink message (563).

13. A computer-readable medium comprising instructions stored thereon, the instructions being configured to cause a terminal device (510) for wireless communication to perform at least the method according to claim 12.

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