Requirements for known transmission configuration indicator state in asymmetric downlink / uplink transmission-reception point

Abstract

Example embodiments of the present disclosure are directed to known Transmission Configuration Indicator (TCI) state in asymmetric Downlink (DL) / Uplink (UL) Transmission-Reception Point (TRP) A method comprises receiving, from a second apparatus, a TCI state switch command; in accordance with a determination that the TCI state switch command indicates a TCI state switching from a first TCI state to a second TCI state, determining based on a validity timer associated with an uplink reference signal transmission corresponding to the second TCI state or with a reception of an indication of a pathloss offset corresponding to the second TCI state, the second TCI state to be known or unknown.

Description

REQUIREMENTS FOR KNOWN TRANSMISSION CONFIGURATION INDICATOR STATE IN ASYMMETRIC DOWN LIN K / U PLINK TRANSMISSION-RECEPTION POINTCROSS-REFERENCE TO RELATED APPLICATION

[0001] This application claims priority from, and the benefit of, India Provisional Application No. 202441075206, filed October 4, 2024, which is hereby incorporated by reference in its entirety.FIELD

[0002] Various example embodiments of the present disclosure generally relate to the field of telecommunication and in particular, to methods, devices, apparatuses and computer readable storage medium for requirements for known Transmission Configuration Indicator (TCI) state in asymmetric Downlink (DL) / Uplink (UL) Transmission-Reception Point (TRP).BACKGROUND

[0003] The requirements for unified TCI state switch delay are defined in Radio Resource Management (RRM) requirements for a TRP with symmetric uplink and downlink. All of these switching delay requirements are defined based on a TCI state being known or unknown. For a TCI state to be considered as known there are set of conditions defined which are primarily centered around a downlink reference signal being transmitted by the TRP.SUMMARY

[0004] In a first aspect of the present disclosure, there is provided a first apparatus. The first apparatus comprises at least one processor; and at least one memory storing instructions that, when executed by the at least one processor, cause the first apparatus at least to: receive, from a second apparatus, a transmission configuration indicator, TCI, state switch command; in accordance with a determination that the TCI state switch command indicates a TCI state switching from a first TCI state to a second TCI state, determine, based on a validity timer associated with an uplink reference signal transmission corresponding to the second TCI state or with a reception of an indication of a pathloss offset corresponding to the second TCI state, the second TCI state to be known or unknown.

[0005] In a second aspect of the present disclosure, there is provided a second apparatus. The second apparatus comprises at least one processor; and at least one memory storing instructions that, when executed by the at least one processor, cause the second apparatus at least to: configure, to a first apparatus, a second transmission configuration indicator, TCI, state associated with an uplink reference signal transmission; configure, to the first apparatus, a validity timer associated with determining whether the TCI state is considered as being known or unknown after a reception of a TCI state switch command indicating a TCI state switching from a first TCI state to the second TCIstate; and transmit the TCI state switch command to the first apparatus.

[0006] In a third aspect of the present disclosure, there is provided a method. The method comprises: receiving, from a second apparatus, a transmission configuration indicator, TCI, state switch command; in accordance with a determination that the TCI state switch command indicates a TCI state switching from a first TCI state to a second TCI state, determining based on a validity timer associated with an uplink reference signal transmission corresponding to the second TCI state or with a reception of an indication of a pathloss offset corresponding to the second TCI state, the second TCI state to be known or unknown.

[0007] In a fourth aspect of the present disclosure, there is provided a method. The method comprises: configuring, to a first apparatus, a second transmission configuration indicator, TCI, state associated with an uplink reference signal transmission; configuring, to the first apparatus, a validity timer associated with determining whether the TCI state is considered as being known or unknown after a reception of a TCI state switch command indicating a TCI state switching from a first TCI state to the second TCI state; and transmitting the TCI state switch command to the first apparatus.

[0008] In a fifth aspect of the present disclosure, there is provided a first apparatus. The first apparatus comprises means for receiving, from a second apparatus, a transmission configuration indicator, TCI, state switch command; means for in accordance with a determination that the TCI state switch command indicates a TCI state switching from a first TCI state to a second TCI state, determining based on a validity timer associated with an uplink reference signal transmission corresponding to the second TCI state or with a reception of an indication of a pathloss offset corresponding to the second TCI state, the second TCI state to be known or unknown.

[0009] In a sixth aspect of the present disclosure, there is provided a second apparatus. The second apparatus comprises means for configuring, to a first apparatus, a second transmission configuration indicator, TCI, state associated with an uplink reference signal transmission; means for configuring, to the first apparatus, a validity timer associated with determining whether the TCI state is considered as being known or unknown after a reception of a TCI state switch command indicating a TCI state switching from a first TCI state to the second TCI state; and means for transmitting the TCI state switch command to the first apparatus.

[0010] In a seventh aspect of the present disclosure, there is provided a computer readable medium. The computer readable medium comprises instructions stored thereon for causing an apparatus to perform at least the method according to the third aspect.

[0011] In an eighth aspect of the present disclosure, there is provided a computer readable medium. The computer readable medium comprises instructions stored thereon for causing an apparatus to perform at least the method according to the fourth aspect.

[0012] It is to be understood that the Summary section is not intended to identify key or essentialfeatures of embodiments of the present disclosure, nor is it intended to be used to limit the scope of the present disclosure. Other features of the present disclosure will become easily comprehensible through the following description.BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Some example embodiments will now be described with reference to the accompanying drawings, where:

[0014] FIG. 1 illustrates an example communication environment in which example embodiments of the present disclosure can be implemented;

[0015] FIG. 2 illustrates a schematic diagram of Quasi Co-Location (QCL) and TCI chains according to a previously discussed scheme;

[0016] FIG. 3 illustrates a signaling chart of communication according to some example embodiments of the present disclosure;

[0017] FIG. 4 illustrates a flowchart of a method implemented at a first apparatus in accordance with some example embodiments of the present disclosure;

[0018] FIG. 5 illustrates a flowchart of a method implemented at a second apparatus in accordance with some example embodiments of the present disclosure;

[0019] FIG. 6 illustrates a simplified block diagram of a device that is suitable for implementing example embodiments of the present disclosure; and

[0020] FIG. 7 illustrates a block diagram of an example computer readable medium in accordance with some example embodiments of the present disclosure.

[0021] Throughout the drawings, the same or similar reference numerals represent the same or similar element.DETAILED DESCRIPTION

[0022] Principle of the present disclosure will now be described with reference to some example embodiments. It is to be understood that these embodiments are described only for the purpose of illustration and help those skilled in the art to understand and implement the present disclosure, without suggesting any limitation as to the scope of the disclosure. Embodiments described herein can be implemented in various manners other than the ones described below.

[0023] In the following description and claims, unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skills in the art to which this disclosure belongs.

[0024] References in the present disclosure to “one embodiment,” “an embodiment,” “an example embodiment,” and the like indicate that the embodiment described may include a particular feature, structure, or characteristic, but it is not necessary that every embodiment includes the particularfeature, structure, or characteristic. Moreover, such phrases are not necessarily referring to the same embodiment. Further, when a particular feature, structure, or characteristic is described in connection with an embodiment, it is submitted that it is within the knowledge of one skilled in the art to affect such feature, structure, or characteristic in connection with other embodiments whether or not explicitly described.

[0025] It shall be understood that although the terms “first,” “second,”..., etc. in front of noun(s) and the like may be used herein to describe various elements, these elements should not be limited by these terms. These terms are only used to distinguish one element from another and they do not limit the order of the noun(s). For example, a first element could be termed a second element, and similarly, a second element could be termed a first element, without departing from the scope of example embodiments. As used herein, the term “and / or” includes any and all combinations of one or more of the listed terms.

[0026] As used herein, “at least one of the following: ” and “at least one of ” and similar wording, where the list of two or more elements are joined by “and” or “or”, mean at least any one of the elements, or at least any two or more of the elements, or at least all the elements.

[0027] As used herein, unless stated explicitly, performing a step “in response to A” does not indicate that the step is performed immediately after “A” occurs and one or more intervening steps may be included.

[0028] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of example embodiments. As used herein, the singular forms “a”, “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “comprises”, “comprising”, “has”, “having”, “includes” and / or “including”, when used herein, specify the presence of stated features, elements, and / or components etc., but do not preclude the presence or addition of one or more other features, elements, components and / or combinations thereof.

[0029] As used in this application, the term “circuitry” may refer to one or more or all of the following:(a) hardware-only circuit implementations (such as implementations in only analog and / or digital circuitry) and(b) combinations of hardware circuits and software, such as (as applicable):(i) a combination of analog and / or digital hardware circuit(s) with software / firmware and(ii) any portions of hardware processor(s) with software (including digital signal processor(s)), software, and memory(ies) that work together to cause an apparatus, such as a mobile phone or server, to perform various functions) and(c) hardware circuit(s) and or processor(s), such as a microprocessor(s) or a portion of a microprocessor(s), that requires software (e.g., firmware) for operation, but the software may not be present when it is not needed for operation.

[0030] This definition of circuitry applies to all uses of this term in this application, including in any claims. As a further example, as used in this application, the term circuitry also covers an implementation of merely a hardware circuit or processor (or multiple processors) or portion of a hardware circuit or processor and its (or their) accompanying software and / or firmware. The term circuitry also covers, for example and if applicable to the particular claim element, a baseband integrated circuit or processor integrated circuit for a mobile device or a similar integrated circuit in server, a cellular network device, or other computing or network device.

[0031] As used herein, the term “communication network” refers to a network following any suitable communication standards, such as New Radio (NR), Long Term Evolution (LTE), LTE-Advanced (LTE- A), Wideband Code Division Multiple Access (WCDMA), High-Speed Packet Access (HSPA), Narrow Band Internet of Things (NB-loT) and so on. Furthermore, the communications between a terminal device and a network device in the communication network may be performed according to any suitable generation communication protocols, including, but not limited to, the first generation (1 G), the second generation (2G), 2.5G, 2.75G, the third generation (3G), the fourth generation (4G), 4.5G, the fifth generation (5G), 5.5G, the sixth generation (6G) communication protocols, and / or any other protocols either currently known or to be developed in the future. Embodiments of the present disclosure may be applied in various communication systems. Given the rapid development in communications, there will of course also be future types of communication technologies and systems with which the present disclosure may be embodied. It should not be seen as limiting the scope of the present disclosure to only the aforementioned system.

[0032] As used herein, the term “network device” refers to a node in a communication network via which a terminal device accesses the network and receives services therefrom. The network device may refer to a base station (BS) or an access point (AP), for example, a node B (NodeB or NB), an evolved NodeB (eNodeB or eNB), an NR NB (also referred to as a gNB), a Remote Radio Unit (RRU), a radio header (RH), a remote radio head (RRH), a relay, an Integrated Access and Backhaul (I AB) node, a low power node such as a femto, a pico, a non-terrestrial network (NTN) or non-ground network device such as a satellite network device, a low earth orbit (LEO) satellite and a geosynchronous earth orbit (GEO) satellite, an aircraft network device, and so forth, depending on the applied terminology and technology. In some example embodiments, radio access network (RAN) split architecture comprises a Centralized Unit (CU) and a Distributed Unit (DU) at an IAB donor node. An IAB node comprises a Mobile Terminal (IAB-MT) part that behaves like a UE toward the parent node, and a DU part of an IAB node behaves like a base station toward the next-hop IAB node.

[0033] The term “terminal device” refers to any end device that may be capable of wireless communication. By way of example rather than limitation, a terminal device may also be referred to as a communication device, user equipment (UE), a Subscriber Station (SS), a Portable Subscriber Station, a Mobile Station (MS), or an Access Terminal (AT). The terminal device may include, but not limited to, a mobile phone, a cellular phone, a smart phone, voice over IP (VoIP) phones, wireless local loop phones, a tablet, a wearable terminal device, a personal digital assistant (PDA), portable computers, desktop computer, image capture terminal devices such as digital cameras, gaming terminal devices, music storage and playback appliances, vehicle-mounted wireless terminal devices, wireless endpoints, mobile stations, laptop-embedded equipment (LEE), laptop-mounted equipment (LME), USB dongles, smart devices, wireless customer-premises equipment (CPE), an Internet of Things (loT) device, a watch or other wearable, a head-mounted display (HMD), a vehicle, a drone, a medical device and applications (e.g., remote surgery), an industrial device and applications (e.g., a robot and / or other wireless devices operating in an industrial and / or an automated processing chain contexts), a consumer electronics device, a device operating on commercial and / or industrial wireless networks, and the like. The terminal device may also correspond to a Mobile Termination (MT) part of an IAB node (e.g., a relay node). In the following description, the terms “terminal device”, “communication device”, “terminal”, “user equipment” and “UE” may be used interchangeably.

[0034] As used herein, the term “resource,” “transmission resource,” “resource block,” “physical resource block” (PRB), “uplink resource,” or “downlink resource” may refer to any resource for performing a communication, for example, a communication between a terminal device and a network device, such as a resource in time domain, a resource in frequency domain, a resource in space domain, a resource in code domain, or any other combination of the time, frequency, space and / or code domain resource enabling a communication, and the like. In the following, unless explicitly stated, a resource in both frequency domain and time domain will be used as an example of a transmission resource for describing some example embodiments of the present disclosure. It is noted that example embodiments of the present disclosure are equally applicable to other resources in other domains.

[0035] The term “transmission configuration indication (TCI)” used herein may refer to a parameter used in telecommunications systems to indicate the configuration and characteristics of a transmission link or channel. It provides information about the transmission medium, allowing the receiving equipment to properly interpret and process the transmitted data. One TCI may correspond to one beam.

[0036] As used herein, the term “transmission reception point (TRP)” may refer to an antenna port or an antenna array (with one or more antenna elements) available to the network device located at a specific geographical location. For example, a network device may be coupled with multiple TRPs in different geographical locations to achieve better coverage. Alternatively, or in addition, multipleTRPs may be incorporated into a network device, or in other words, the network device may comprise the multiple TRPs. The term “TRP” may be also referred to as a cell, such as a macro-cell, a small cell, a p ico-cel I, a femto-cel I, a remote radio head, a relay node, etc. It is to be understood that the term “TRP” may refer to a logical concept which may be physically implemented by various manner. For example, a TRP may refer to or correspond to a physical cell identity (PCI) or control resource set (CORESET) Pool Index (i.e., CORESETPoollndex).

[0037] FIG. 1 illustrates an example communication environment 100 in which example embodiments of the present disclosure can be implemented. The communication environment 100 may comprise a first apparatus 110, e.g., a UE, which may be referred to as a terminal device, a second apparatus 120-1 and a third apparatus 120-2, e.g., gNBs, which may be referred to as a network device collectively.

[0038] The first apparatus 110 may be served by a cell 101 managed by the second apparatus 120- 1 and a cell 102 managed by the third apparatus 120-2. That is, the first apparatus 110 may communicate with the second apparatus 120-1 within the cell 101 and communicate with third apparatus 120-2 within the cell 102.

[0039] In some scenarios, the second apparatus 120-1 may be considered as a first TRP and the third apparatus 120-2 may be considered as a second TRP. The first apparatus 110 may connect to both first and second TRPs.

[0040] In some example embodiments, a link from the second apparatus 120-1 to the first apparatus 110 is referred to as a downlink (DL), while a link from the first apparatus 110 to the second apparatus 120-1 is referred to as an uplink (UL). In DL, the second apparatus 120-1 is a transmitting (TX) apparatus (or a transmitter) and the first apparatus 110 is a receiving (RX) apparatus (or a receiver). In UL, the first apparatus 110 is a TX apparatus (or a transmitter) and the second apparatus 120-1 is a RX apparatus (or a receiver).

[0041] Meanwhile, for the third apparatus 120-2, there is only an UL between the first apparatus 110 and the third apparatus 120-2, that is, during a communication between the first apparatus 110 and the third apparatus 120-2, the first apparatus 110 is always a TX apparatus and the third apparatus 120-2 is always a RX apparatus.

[0042] It is to be understood that the number of devices and their connections shown in FIG. 1 are only for the purpose of illustration without suggesting any limitation. The communication environment 100 may include any suitable number of devices configured to implement example embodiments of the present disclosure.

[0043] Communications in the communication environment 100 may be implemented according to any proper communication protocol(s), comprising, but not limited to, cellular communication protocols of the first generation (1G), the second generation (2G), the third generation (3G), the fourthgeneration (4G), the fifth generation (5G), 5.5G, the sixth generation (6G), and the like, wireless local network communication protocols such as Institute for Electrical and Electronics Engineers (IEEE) 802.11 and the like, and / or any other protocols currently known or to be developed in the future. Moreover, the communication may utilize any proper wireless communication technology, comprising but not limited to: Code Division Multiple Access (CDMA), Frequency Division Multiple Access (FDMA), Time Division Multiple Access (TDMA), Frequency Division Duplex (FDD), Time Division Duplex (TDD), Multiple-Input Multiple-Output (MIMO), Orthogonal Frequency Division Multiple (OFDM), Discrete Fourier Transform spread OFDM (DFT-s-OFDM) and / or any other technologies currently known or to be developed in the future.

[0044] Referring to FIG.1 , the second apparatus 120-2 may be referred to as TRP 1 and the third apparatus may be referred to as TRP 2. The situation shown in FIG. 1 where there are both UL and DL between the TRP 1 and the first apparatus 110, while there is only UL exist between the TRP 2 and the first apparatus 110 can be referred to as “asymmetric DL / UL TRP”.

[0045] Enhancements for asymmetric DL single TRP (sTRP) / UL multi-TRP (mTRP) deployment scenarios were specified in New Radio (NR) Multiple Input Multiple Output (MIMO), assuming intraband intra-distributed unit (DU) non-co-located mTRP scenarios, without changing existing cell definition or defining a new cell (e.g. UL-only cell), assuming the unified TCI framework and fully reusing the legacy QCL / UL spatial relation rules, targeting Frequency Range 1 (FR1) and Frequency Range 2 (FR2).

[0046] An asymmetric DL / UL TRP is essentially a heterogeneous Network (hetnet) which will comprise of a macro gNB (having both DL and UL) and a micro gNB having UL only.

[0047] This kind of deployment can be used in urban scenarios to improve the UE uplink throughput. Since the macro gNB and micro nodes differ in power rating, a UE may receive DL transmission from the macro gNB but transmit UL to either the macro gNB or non-co-located micro nodes in order to maximize UL throughput.

[0048] In some discussed schemes, unified TCI / lnter-Cell Beam Management (ICBM) and unified TCI framework were agreed to be reused, the conclusion of the agreements is shown in the following Table 1 : Table 1 :_0049] Similarly, in some discussed scheme, it was agreed to study and if required, specify :heRadio Resource Management (RRM) requirements for TCI state switching requirements. Some enhancement for asymmetric DL sTRP / UL mTRP scenarios is shown in the following Table 2.Table 2:_ _ 0050] Since the PL offset value is used for the UL TCI state in the UL only TRP, this will have a bearing on the TCI uplink switching delay requirements.

[0051] NR cell may comprise one or multiple TRPs. TRPs of the same cell have a common Synchronization Signal / Physical Broadcast Channel (SS / PBCH) block which is cell specific. In Multiple Transmit / Receive Point (multi-TRP) operation, a serving cell can schedule the UE from two TRPs, providing better coverage, reliability and / or data rates for Physical Downlink Shared Channel (PDSCH), Physical Downlink Control Channel (PDCCH), Physical Uplink Shared Channel (PUSCH), and Physical Uplink Control Channel (PUCCH).

[0052] There are two different operation modes to schedule multi-TRP transmissions: singledownlink control information (DCI) and multi-DCI. For both modes, control of uplink and downlink operation can be done by physical layer and MAC layer, within the configuration provided by the Radio Resource Control (RRC) layer. In single-DCI mode, only one TRP is responsible for the transmission of control data (via PDCCH) to the UE. As a result, the UE is scheduled by the same PDCCH containing a DCI for both TRPs. On the other hand, in multi-DCI mode two TRPs are responsible for the transmission of control data to the UE. As a result, the UE is scheduled by independent DCIs from each TRP. With reference to the asymmetric DL / UL mTRP scenario, since there will only be a single downlink to the UE, it will a be s-DCI mode of operation.

[0053] The reference is now made to FIG. 2. The FIG. 2 illustrates a schematic diagram of QCL and TCI chains according to a previously discussed scheme.

[0054] QCL framework is used for beam indication. The gNB provided beam indication information is used to configure the UE with the information of which transmit (Tx) beam is to be used for downlink DL (and the UE can select proper Receive Rx beam) and which Tx beam is to be used for UL (so that UE’s Tx is “directed” towards used RX beam at gNB).

[0055] The UE can be configured with a list of up to M TCI-State configurations within the higherlayer parameter PDSCH Configuration to decode PDSCH according to a detected PDCCH with DCI intended for the UE and the given serving cell, where M depends on the UE capability “maxNumberConfiguredTCIstatesPerCC”.

[0056] Each TCI-State contains parameters for configuring a quasi-co-location relationship between one or two downlink RS and the Demodulation-Reference Signal (DM-RS) ports of the PDSCH, the DM-RS port of PDCCH or the Channel State Information-Reference Signal (CSI-RS) port(s) of a CSI- RS resource. The quasi-co-location relationship is configured by the higher layer parameter qcl-Type1 for the first DL RS, and qcl-Type2 for the second DL RS (if configured). For the case of two DL RSs, the QCL types shall not be the same, regardless of whether the references are to the same DL RS or different DL RSs.

[0057] The quasi-co-location types corresponding to each DL RS are given by the higher layer parameter QCL-Type in QCL-Info and may take one of the following values:• QCL types A: Doppler shift, Doppler spread, average delay, delay spread• QCL types B: Doppler shift, Doppler spread• QCL types C: average delay, Doppler shift• QCL types D: Spatial Rx

[0058] The main tool for beam indication for downlink is a TCI framework. A UE can be configured with up to 128 TCI states. The gNB configures the UE via RRC signaling with TCI states where each TCI states may have one or two source RSs that provide QCL parameters for the target RS - only one RS providing QCL type D per TCI state. A DL TCI chain consists of a Synchronization Signal Block (SSB), and one or more CSI-RS resources, and the TCI state of each Reference Signal includes another Reference Signal in the same TCI chain, where the SSB can be associated with serving cell Physical-layer Cell Identity (PCID) or associated with a PCID different from serving cell PCID.

[0059] DM-RS of PDCCH or PDSCH is QCLed with the reference signal in its active TCI state and any other reference signal that is QCLed, based on the criteria for DL TCI chain, with the reference signal in the active TCI state.

[0060] TCI state switching delay requirements have been defined in some discussed schemes for unified TCI and the same is expected to be used as a baseline while defining requirements for TCI state switching in the asymmetric DL / UL context. The defined TCI state switching delay requirements in some discussed schemes are dependent on the target TCI state being known or unknown.

[0061] Conditions for the TCI state to be considered as known are shown in the following Table 3: Table 3:_0062] When a TCI state is unknown, MAC-CE based switching delay (in case of FR2) is longer as compared to when a TCI state is known as the UE has to send an additional L1 -RSRP report before it can transmit with the target TCI state. When the TCI state is unknown or known, the UE may take the following actions as shown in Table 4:Table 4:0063] In case of DCI based TCI state switch, the switching requirements will apply only if a set of conditions are fulfilled, one of which is the target TCI state being known in the following Table 5:Table 5:0064] The TCI state switching delay requirements in some discussed schemes have been defined for m-TRP scenarios with symmetric uplink and downlink.

[0065] TCI state switch delay requirements for asymmetric UL / DL m-TRP scenario will be defined in some future schemes.

[0066] As described above, the requirements for unified TCI state switch delay are defined in RRM requirements in some discussed schemes for a TRP with symmetric uplink and downlink. All of these switching delay requirements are defined based on a TCI state being known or unknown. For a TCI state to be considered as known there are set of conditions defined which are primarily centered around a downlink reference signal being transmitted by the TRP.

[0067] For example, for the TCI state to be considered known, the UE should have transmitted a L1 -RSRP report for the target UL TCI state and the UL TCI state switch command should be received within 1280 ms of the last transmission of the reference signal.

[0068] Both these conditions imply that there is a reference signal transmitted in the downlink by the TRP.

[0069] However, in case of an asymmetric DL / UL TRP, the uplink only TRP does not transmit any reference signal. This then implies that the conditions defined in some discussed schemes for an uplink TCI state to be known cannot be used in the context of an asymmetric DL / UL TRP.

[0070] Without defining applicability / known conditions for TCI state switching delay requirements specific to asymmetric DL / UL TRP, it will not be possible to define reasonable TCI state switch delay requirements (i.e. when can the UE and the network expect longer TCI state switch delay and when can the UE and the network expect a relatively shorter TCI state switch delay).

[0071] The problem in some discussed schemes is that how to define applicability / known conditionsfor a target TCI state associated with a TRP which does not transmit any downlink reference signal.

[0072] In accordance with some example embodiments of the present disclosure, there is provided a solution for requirements for known TCI state in asymmetric DL / UL TRP. In this solution, the first apparatus 110 receives a TCI state switch command indicating a TCI state switching from a first TCI state to a second TCI state, and determine the second TCI state to be known and unknown based on a validity timer.

[0073] Based on the validity timer, if the first apparatus 110 determines second TCI state to be unknown, the first apparatus 110 may complete the TCI state switching to the second TCI state within a first time period, and if the first apparatus 110 determines that second TCI state to be known, the first apparatus 110 may complete the TCI state switching to the second TCI state within a second time period. In this way, target uplink TCI state switching time can be reduced if a UE has transmitted an uplink reference signal which is Quasi Co-Located to the target uplink TCI state.

[0074] Example embodiments of the present disclosure will be described in detail below with reference to the accompanying drawings.

[0075] Reference is now made to FIG. 3, which shows a signaling chart 300 for communication according to some example embodiments of the present disclosure. As shown in FIG. 3, the signaling chart 300 involves a first apparatus 110, a second apparatus 120-1 and a third apparatus 120-2. For the purpose of discussion, reference is made to FIG. 1 to describe the signaling chart 300.

[0076] The applicability conditions for uplink TCI state switch for an uplink-only TRP is shown in the following Table 6:Table 6:0077] The condition shown in Table 6 will be described in detail below in connection with FIG. 3.

[0078] As shown in FIG. 3, the second apparatus 120-1 configure (310) the first apparatus 110 with a single DCI (sDCI) multi-TRP (mTRP) state, wherein the second apparatus 120-1 is the DL / UL capable TRP and the third apparatus 120-2 is the UL-only TRP.

[0079] In some embodiments, the second apparatus 120-1 also configure (315) the first apparatus 110 with a separate DL TCI state (which may be referred as TCI#1 as well) and a separate UL TCI state (which may be referred as TCI#2 as well) having a Sounding Reference Signal#2 (SRS#2) as Reference Signal (RS). After the configuration of the TCI state is finished, the second apparatus 120- 1 may perform (320) the DL transmission from the second apparatus 120-1 to the first apparatus 110 based on the configuration of TCI#1, and the first apparatus 110 may perform (325) the UL transmission from the first apparatus 110 to the third apparatus 120-2.

[0080] In particular, these two TCI states (TCI#1 and TIC#2) at step 320 and 325 are also activated / indicated, and the TCI#1 and the TCI#2 are the only TCI states that are configured at step 315.

[0081] In some embodiments, the second apparatus 120-1 may configure (330) the first apparatus 110 with another UL TCI state (which may be referred to as TCI#3 as well). It should be noted that in the scenario shown in FIG. 3 the TCI#3 may be a new TCI state to be switch to. Moreover, the RS associated to the TCI#3 is the SRS#3, which is different from the TCI#2 that is associated to another SRS, i.e., SRS#2.

[0082] In some embodiments, the second apparatus 120-1 configure (335) the first apparatus 110 to perform a transmission of the SRS#3. Then, the first apparatus 110 perform (340) the transmission of the SRS#3 based on the configuration. Specifically, the transmission of the SRS#3may also happen before step 330 in some other embodiments.

[0083] In some embodiments, uplink reference signal transmission (i.e., SRS#3) may comprise a sounding reference signal transmission or a demodulation reference signal transmission or a phase tracking reference signal transmission. For example, this uplink reference signal may be an SRS, while in some other embodiments this uplink reference signal may also be a Demodulation Reference Signal (DMRS) or a Phase Tracking Reference Signal (PTRS).

[0084] In some embodiments, the first apparatus 110 may receive (345), from a second apparatus 120-1 , a TCI state switch command.

[0085] For example, the network (i.e., the second apparatus 120-1) may send a TCI switching command to the UE (i.e., the first apparatus 110) to switch the UL TCI state from TCI#2 to TCI#3.

[0086] It should be noted that, since the intent described herein is to switch the TCI state of TCI#2 to the TCI state of TCI#3, the TCI#2 herein may also be referred to as a first TCI state, and the TCI#3 may also be referred to as the second TCI state or a target TCI state.

[0087] In some embodiments, the second TCI state indicated in the TCI state switch command is an uplink TCI state to be applied for a TRP that supports an uplink transmission and does not support a downlink transmission. Specifically, such TRP may be the third apparatus 120-2 that supports a UL transmission only.

[0088] According to the solution proposed in the present disclosure, known / applicability conditions for a target TCI state in case of an uplink only TRP, or a TCI state that corresponds to an UL-only TRP / node, shall be based on the UE having transmitted an uplink reference signal prior to the TCI state switch, that is, a time point when the uplink reference signal transmission corresponding to the second TCI state is transmitted by the first apparatus 110. This reference signal shall either be a reference signal in the target uplink TCI state configuration or shall have a QCL relation to the target uplink TCI state.

[0089] Furthermore, the known / applicability conditions may further be determined by the first apparatus 110 based on a validity timer, which may be configured by the second apparatus 120-1 , and the validity timer may be transmitted to the first apparatus 110 via an RRC message.

[0090] In the solution proposed by the present disclosure, the first apparatus 110 (i.e., the UE) need to determine whether the TCI switching is a “fast” TCI switching or a “slow” TCI switching based on the known / applicability conditions. Specifically, the TCI switching is a “fast / short” TCI switching when the TCI state is considered as “known”, and the TCI switching is a “slow / long” TCI switching when the TCI state is considered as “unknown”.

[0091] In some embodiments, as the first option, the validity timer may correspond to an offset relative to a time point when the uplink reference signal transmission corresponding to the second TCI state is transmitted by the first apparatus.

[0092] For example, the known / applicability conditions, including the validity timer, for a target TCI state, or the switching delay for the TCI state (where this switching may be via DCI or MAC CE etc.), may be based on a time offset from / after the time of transmission of the SRS corresponding to the target TCI state.

[0093] In some cases, the offset may be a fixed value, e.g., 500 ms or 1280 ms.

[0094] In some other options the offset could be a variable value, and the determination of the offset may be different in different cases:

[0095] In some cases, the offset may be dependent on other parameters. In some embodiments, the offset may be determined based on a periodicity of an uplink reference signal, e.g., as a fraction of the SRS periodicity (in one example the offset could be defined as 50% of the SRS periodicity, so if the SRS periodicity is 320 ms then the offset is 160 ms, whereas if the SRS periodicity is 160 ms then the offset is 80 ms).

[0096] In another embodiment, the offset may be determined based on the time period within which a TCI state is to be considered as being known after sending an uplink reference signal associated with the TCI state. For example, when the SRS transmissions are aperiodic and triggered by the network, and the time offset is used to determine how long after the SRS transmission the gNB may send the TCI switch command while the TCI state is still known

[0097] In yet another embodiment, the offset may also be configured by the network, e.g., via RRC.

[0098] In some embodiments, as the second option, the validity timer may correspond to an offset relative to a time point when the indication of the pathloss offset corresponding to the second TCI state is received by the first apparatus or when the first apparatus is indicated with the pathloss offset corresponding to the second TCI state.

[0099] In some embodiments, the indication of the pathloss offset refers to a configuration of the pathloss offset or an update of the pathloss offset.

[0100] For example, the known / applicability conditions, including the validity timer, for a target TCI state, or the switching delay for the TCI state (where this switching may be via DCI or MAC CE etc.), may be based on (i) the UE receiving configuration or indication or update of a pathloss offset associated with the TCI state or (ii) a pathloss offset value being indicated or updated which is associated to the TCI state.

[0101] It should be noted that, the offset mentioned above may also be regarded as a time offset or offset “W” in the following discussion.

[0102] In some embodiments, if the first apparatus 110 determines that the TCI state switch command indicates a TCI state switching from a first TCI state to a second TCI state, the first apparatus 110 may determine, based on a validity timer associated with an uplink reference signal transmission corresponding to the second TCI state or with a reception of an indication of a pathloss offset corresponding to the second TCI state, the second TCI state to be known or unknown.

[0103] In some embodiments, in order to determine the second TCI state to be known and unknown, at block 350, the first apparatus 110 may determine whether a time window between the time point and the reception of the TCI state switch command does not exceed the offset. For example, the UE determines the time T (i.e. , the time window) between the TCI switching command (at step 345) and the last transmission of SRS#3 (at step 340).

[0104] In some embodiment, at block 355, if the first apparatus 110 determines that the time window is larger than the offset, the first apparatus 110 may determine the second TCI state to be unknown. Then the first apparatus 110 may complete the TCI state switching to the second TCI state within a first time period. Specifically, the first time period may be a time period corresponding to the “slow / long” TCI switch.

[0105] For example, if T is greater than the specified time offset W (block 355), then the TCI#3 (i.e., the target TCI state to be switched to) is determined to be unknown, and slow / long TCI switching requirements apply.

[0106] In some embodiment, at block 360, if the first apparatus 110 determines that the time window does not exceed the offset, the first apparatus 110 may determine the second TCI state to be known. Then the first apparatus 110 may complete the TCI state switching to the second TCI state within asecond time period, wherein the second time period is shorter than the first time period. Specifically, the second time period may be a time period corresponding to the “fast / short” TCI switch.

[0107] For example, if T is smaller or equal to the specified time offset W (block 360), then the TCI#3 is determined to be known, and fast / short TCI switching requirements apply, so UL transmission on target TCI#3 can start sooner when compared to the unknown case.

[0108] Finally, upon determining whether the target TCI state is known or unknown, and applying the corresponding TCI switching requirements, the first apparatus may perform (365) the UL transmission to the third apparatus 120-2 based on the configured TCI#3.

[0109] The solutions proposed in the present disclosure can reduce the target uplink TCI state switching time if a UE has transmitted an uplink reference signal which is Quasi Co-Located (i.e., known) to the target uplink TCI state.

[0110] FIG. 4 shows a flowchart of an example method 400 implemented at a first apparatus in accordance with some example embodiments of the present disclosure. For the purpose of discussion, the method 400 will be described from the perspective of the first apparatus 110 in FIG. 1.

[0111] At block 410, the first apparatus receives, from a second apparatus, a transmission configuration indicator, TCI, state switch command.

[0112] At block 420, in accordance with a determination that the TCI state switch command indicates a TCI state switching from a first TCI state to a second TCI state, at block 430, the first apparatus determines, based on a validity timer associated with an uplink reference signal transmission corresponding to the second TCI state or with a reception of an indication of a pathloss offset corresponding to the second TCI state, the second TCI state to be known or unknown.

[0113] In some example embodiments, the validity timer corresponds to an offset relative to a time point when the uplink reference signal transmission corresponding to the second TCI state is transmitted by the first apparatus.

[0114] In some example embodiments, the method 400 further comprises: determining whether a time window between the time point and the reception of the TCI state switch command does not exceed the offset; and in accordance with a determination that the time window is larger than the offset, determining the second TCI state to be unknown; and completing the TCI state switching to the second TCI state within a first time period.

[0115] In some example embodiments, the method 400 further comprises: in accordance with a determination that the time window does not exceed the offset, determining the second TCI state to be known; and completing the TCI state switching to the second TCI state within a second time period, wherein the second time period is shorter than the first time period.

[0116] In some example embodiments, the validity timer corresponds to an offset relative to a time point when the indication of the pathloss offset corresponding to the second TCI state is received bythe first apparatus or when the first apparatus is indicated with the pathloss offset corresponding to the second TCI state.

[0117] In some example embodiments, the method 400 further comprises: determining whether a time window between the time point and the reception of the TCI state switch command does not exceed the offset; and in accordance with a determination that the time window is larger than the offset, determining the second TCI state to be unknown; and completing the TCI state switching to the second TCI state within a first time period.

[0118] In some example embodiments, the method 400 further comprises: in accordance with a determination that the time window does not exceed the offset, determining the second TCI state to be known; and completing the TCI state switching to the second TCI state within a second time period, wherein the second time period is shorter than the first time period.

[0119] In some example embodiments, the offset is set to a fixed value.

[0120] In some example embodiments, the offset is a variable value.

[0121] In some example embodiments, the offset is determined based on one of the following: a periodicity of an uplink reference signal, or a time period within which a TCI state is to be considered as being known after sending an uplink reference signal associated with the TCI state.

[0122] In some example embodiments, the offset is indicated by the second apparatus via a radio resource control signaling.

[0123] In some example embodiments, the second TCI state indicated in the TCI state switch command is an uplink TCI state to be applied for a transmission reception point, TRP, that supports an uplink transmission and does not support a downlink transmission.

[0124] In some example embodiments, the indication of the pathloss offset refers to a configuration of the pathloss offset or an update of the pathloss offset.

[0125] In some example embodiments, the uplink reference signal transmission comprises at least one of the following: a sounding reference signal transmission, a demodulation reference signal transmission, or a phase tracking reference signal transmission.

[0126] In some example embodiments, the first apparatus comprises a terminal device and the second apparatus comprises a network device.

[0127] FIG. 5 shows a flowchart of an example method 500 implemented at a second apparatus in accordance with some example embodiments of the present disclosure. For the purpose of discussion, the method 500 will be described from the perspective of the second apparatus 120 in FIG. 1.

[0128] At block 510, the second apparatus configures, to a first apparatus, a second transmission configuration indicator, TCI, state associated with an uplink reference signal transmission.

[0129] At block 520, the second apparatus configures, to the first apparatus, a validity timer associated with determining whether the TCI state is considered as being known or unknown after areception of a TCI state switch command indicating a TCI state switching from a first TCI state to the second TCI state.

[0130] At block 530, the second apparatus transmits the TCI state switch command to the first apparatus.

[0131] In some example embodiments, the validity timer corresponds to an offset relative to a time point when the uplink reference signal transmission corresponding to the second TCI state is transmitted by the first apparatus.

[0132] In some example embodiments, the validity timer corresponds to an offset relative to a time point when an indication of a pathloss offset corresponding to the second TCI state is received by the first apparatus or when the first apparatus is indicated with the pathloss offset corresponding to the second TCI state.

[0133] In some example embodiments, the offset is set to a fixed value.

[0134] In some example embodiments, the offset is indicated by the second apparatus via a radio resource control signaling.

[0135] In some example embodiments, the second TCI state indicated in the TCI state switch command is an uplink TCI state to be applied for a transmission reception point, TRP, that supports an uplink transmission and does not support a downlink transmission.

[0136] In some example embodiments, the indication of the pathloss offset refers to a configuration of the pathloss offset or an update of the pathloss offset.

[0137] In some example embodiments, the uplink reference signal transmission comprises at least one of the following: a sounding reference signal transmission, a demodulation reference signal transmission, or a phase tracking reference signal transmission.

[0138] In some example embodiments, the first apparatus comprises a terminal device and the second apparatus comprises a network device.

[0139] In some example embodiments, a first apparatus capable of performing any of the method 400 (for example, the first apparatus 110 in FIG. 1 ) may comprise means for performing the respective operations of the method 400. The means may be implemented in any suitable form. For example, the means may be implemented in a circuitry or software module. The first apparatus may be implemented as or included in the first apparatus in FIG. 1 .

[0140] In some example embodiments, the first apparatus comprises means for receiving, from a second apparatus, a transmission configuration indicator, TCI, state switch command; means for in accordance with a determination that the TCI state switch command indicates a TCI state switching from a first TCI state to a second TCI state, determining based on a validity timer associated with an uplink reference signal transmission corresponding to the second TCI state or with a reception of an indication of a pathloss offset corresponding to the second TCI state, the second TCI state to beknown or unknown.

[0141] In some example embodiments, the validity timer corresponds to an offset relative to a time point when the uplink reference signal transmission corresponding to the second TCI state is transmitted by the first apparatus.

[0142] In some example embodiments, the first apparatus further comprises: means for determining whether a time window between the time point and the reception of the TCI state switch command does not exceed the offset; and means for in accordance with a determination that the time window is larger than the offset, determining the second TCI state to be unknown; and means for completing the TCI state switching to the second TCI state within a first time period.

[0143] In some example embodiments, the first apparatus further comprises: means for in accordance with a determination that the time window does not exceed the offset, determining the second TCI state to be known; and means for completing the TCI state switching to the second TCI state within a second time period, wherein the second time period is shorter than the first time period.

[0144] In some example embodiments, the validity timer corresponds to an offset relative to a time point when the indication of the pathloss offset corresponding to the second TCI state is received by the first apparatus or when the first apparatus is indicated with the pathloss offset corresponding to the second TCI state.

[0145] In some example embodiments, the first apparatus further comprises: means for determining whether a time window between the time point and the reception of the TCI state switch command does not exceed the offset; and means for in accordance with a determination that the time window is larger than the offset, determining the second TCI state to be unknown; and means for completing the TCI state switching to the second TCI state within a first time period.

[0146] In some example embodiments, the first apparatus further comprises: means for in accordance with a determination that the time window does not exceed the offset, determining the second TCI state to be known; and means for completing the TCI state switching to the second TCI state within a second time period, wherein the second time period is shorter than the first time period.

[0147] In some example embodiments, the offset is set to a fixed value.

[0148] In some example embodiments, the offset is a variable value.

[0149] In some example embodiments, the offset is determined based on one of the following: a periodicity of an uplink reference signal, or a time period within which a TCI state is to be considered as being known after sending an uplink reference signal associated with the TCI state.

[0150] In some example embodiments, the offset is indicated by the second apparatus via a radio resource control signaling.

[0151] In some example embodiments, the second TCI state indicated in the TCI state switch command is an uplink TCI state to be applied for a transmission reception point, TRP, that supportsan uplink transmission and does not support a downlink transmission.

[0152] In some example embodiments, the indication of the pathloss offset refers to a configuration of the pathloss offset or an update of the pathloss offset.

[0153] In some example embodiments, the uplink reference signal transmission comprises at least one of the following: a sounding reference signal transmission, a demodulation reference signal transmission, or a phase tracking reference signal transmission.

[0154] In some example embodiments, the first apparatus comprises a terminal device and the second apparatus comprises a network device.

[0155] In some example embodiments, a second apparatus capable of performing any of the method 500 (for example, the second apparatus 120 in FIG. 1 ) may comprise means for performing the respective operations of the method 500. The means may be implemented in any suitable form. For example, the means may be implemented in a circuitry or software module. The second apparatus may be implemented as or included in the second apparatus 120 in FIG. 1.

[0156] In some example embodiments, the second apparatus comprises means for configuring, to a first apparatus, a second transmission configuration indicator, TCI, state associated with an uplink reference signal transmission; means for configuring, to the first apparatus, a validity timer associated with determining whether the TCI state is considered as being known or unknown after a reception of a TCI state switch command indicating a TCI state switching from a first TCI state to the second TCI state; and means for transmitting the TCI state switch command to the first apparatus.

[0157] In some example embodiments, the validity timer corresponds to an offset relative to a time point when the uplink reference signal transmission corresponding to the second TCI state is transmitted by the first apparatus.

[0158] In some example embodiments, the validity timer corresponds to an offset relative to a time point when an indication of a pathloss offset corresponding to the second TCI state is received by the first apparatus or when the first apparatus is indicated with the pathloss offset corresponding to the second TCI state.

[0159] In some example embodiments, the offset is set to a fixed value.

[0160] In some example embodiments, the offset is indicated by the second apparatus via a radio resource control signaling.

[0161] In some example embodiments, the second TCI state indicated in the TCI state switch command is an uplink TCI state to be applied for a transmission reception point, TRP, that supports an uplink transmission and does not support a downlink transmission.

[0162] In some example embodiments, the indication of the pathloss offset refers to a configuration of the pathloss offset or an update of the pathloss offset.

[0163] In some example embodiments, the uplink reference signal transmission comprises at leastone of the following: a sounding reference signal transmission, a demodulation reference signal transmission, or a phase tracking reference signal transmission.

[0164] In some example embodiments, the first apparatus comprises a terminal device and the second apparatus comprises a network device.

[0165] FIG. 6 is a simplified block diagram of a device 600 that is suitable for implementing example embodiments of the present disclosure. The device 600 may be provided to implement a communication device, for example, the first apapratus 110 or the second apparatus 120 as shown in FIG. 1. As shown, the device 600 includes one or more processors 610, one or more memories 620 coupled to the processor 610, and one or more communication modules 640 coupled to the processor 610.

[0166] The communication module 640 is for bidirectional communications. The communication module 640 has one or more communication interfaces to facilitate communication with one or more other modules or devices. The communication interfaces may represent any interface that is necessary for communication with other network elements. In some example embodiments, the communication module 640 may include at least one antenna.

[0167] The processor 610 may be of any type suitable to the local technical network and may include one or more of the following: general purpose computers, special purpose computers, microprocessors, digital signal processors (DSPs) and processors based on multicore processor architecture, as non-limiting examples. The device 600 may have multiple processors, such as an application specific integrated circuit chip that is slaved in time to a clock which synchronizes the main processor.

[0168] The memory 620 may include one or more non-volatile memories and one or more volatile memories. Examples of the non-volatile memories include, but are not limited to, a Read Only Memory (ROM) 624, an electrically programmable read only memory (EPROM), a flash memory, a hard disk, a compact disc (CD), a digital video disk (DVD), an optical disk, a laser disk, and other magnetic storage and / or optical storage. Examples of the volatile memories include, but are not limited to, a random-access memory (RAM) 622 and other volatile memories that will not last in the power-down duration.

[0169] A computer program 630 includes computer executable instructions that are executed by the associated processor 610. The instructions of the program 630 may include instructions for performing operations / acts of some example embodiments of the present disclosure. The program 630 may be stored in the memory, e.g., the ROM 624. The processor 610 may perform any suitable actions and processing by loading the program 630 into the RAM 622.

[0170] The example embodiments of the present disclosure may be implemented by means of the program 630 so that the device 600 may perform any process of the disclosure as discussed withreference to FIG. 2 to FIG. 5. The example embodiments of the present disclosure may also be implemented by hardware or by a combination of software and hardware.

[0171] In some example embodiments, the program 630 may be tangibly contained in a computer readable medium which may be included in the device 600 (such as in the memory 620) or other storage devices that are accessible by the device 600. The device 600 may load the program 630 from the computer readable medium to the RAM 622 for execution. In some example embodiments, the computer readable medium may include any types of non-transitory storage medium, such as ROM, EPROM, a flash memory, a hard disk, CD, DVD, and the like. The term “non-transitory,” as used herein, is a limitation of the medium itself (i.e. , tangible, not a signal) as opposed to a limitation on data storage persistency (e.g., RAM vs. ROM).

[0172] FIG. 7 shows an example of the computer readable medium 700 which may be in form of CD, DVD or other optical storage disk. The computer readable medium 700 has the program 630 stored thereon.

[0173] Generally, various embodiments of the present disclosure may be implemented in hardware or special purpose circuits, software, logic or any combination thereof. Some aspects may be implemented in hardware, and other aspects may be implemented in firmware or software which may be executed by a controller, microprocessor or other computing device. Although various aspects of embodiments of the present disclosure are illustrated and described as block diagrams, flowcharts, or using some other pictorial representations, it is to be understood that the block, apparatus, system, technique or method described herein may be implemented in, as non-limiting examples, hardware, software, firmware, special purpose circuits or logic, general purpose hardware or controller or other computing devices, or some combination thereof.

[0174] Some example embodiments of the present 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 those included in program modules, being executed in a device on a target physical or virtual processor, to carry out any of the methods as described above. Generally, program modules include routines, programs, libraries, objects, classes, components, data structures, or the like that perform particular tasks or implement particular abstract data types. The functionality of the program modules may be combined or split between program modules as desired in various embodiments. Machineexecutable instructions for program modules may be executed within a local or distributed device. In a distributed device, program modules may be located in both local and remote storage media.

[0175] Program code for carrying out methods of the present disclosure may be written in any combination of one or more programming languages. The program code may be provided to a processor or controller of a general-purpose computer, special purpose computer, or otherprogrammable data processing apparatus, such that the program code, when executed by the processor or controller, cause the functions / operations specified in the flowcharts and / or block diagrams to be implemented. The program code may execute entirely on a machine, partly on the machine, as a stand-alone software package, partly on the machine and partly on a remote machine or entirely on the remote machine or server.

[0176] In the context of the present disclosure, the computer program code or related data may be carried by any suitable carrier to enable the device, apparatus or processor to perform various processes and operations as described above. Examples of the carrier include a signal, computer readable medium, and the like.

[0177] The computer readable medium may be a computer readable signal medium or a computer readable storage medium. A computer readable medium may include but not limited to an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, or device, or any suitable combination of the foregoing. More specific examples of the computer readable storage medium would include an electrical connection having one or more wires, a portable computer diskette, a hard disk, a random-access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or Flash memory), an optical fiber, a portable compact disc read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination of the foregoing.

[0178] Further, although operations are depicted in a particular order, this should not be understood as requiring that such operations be performed in the particular order shown or in sequential order, or that all illustrated operations be performed, to achieve desirable results. In certain circumstances, multitasking and parallel processing may be advantageous. Likewise, although several specific implementation details are contained in the above discussions, these should not be construed as limitations on the scope of the present disclosure, but rather as descriptions of features that may be specific to particular embodiments. Unless explicitly stated, certain features that are described in the context of separate embodiments may also be implemented in combination in a single embodiment. Conversely, unless explicitly stated, various features that are described in the context of a single embodiment may also be implemented in a plurality of embodiments separately or in any suitable subcombination.

[0179] Although the present disclosure has been described in languages specific to structural features and / or methodological acts, it is to be understood that the present disclosure defined in the appended claims is not necessarily limited to the specific features or acts described above. Rather, the specific features and acts described above are disclosed as example forms of implementing the claims.

Claims

WHAT IS CLAIMED IS:1 . A first apparatus comprising: at least one processor; and at least one memory storing instructions that, when executed by the at least one processor, cause the first apparatus at least to: receive, from a second apparatus, a transmission configuration indicator, TCI, state switch command; in accordance with a determination that the TCI state switch command indicates a TCI state switching from a first TCI state to a second TCI state, determine, based on a validity timer associated with an uplink reference signal transmission corresponding to the second TCI state or with a reception of an indication of a pathloss offset corresponding to the second TCI state, the second TCI state to be known or unknown.

2. The first apparatus of claim 1 , wherein the validity timer corresponds to an offset relative to a time point when the uplink reference signal transmission corresponding to the second TCI state is transmitted by the first apparatus.

3. The first apparatus of claim 2, wherein the first apparatus is caused to: determine whether a time window between the time point and the reception of the TCI state switch command does not exceed the offset; and in accordance with a determination that the time window is larger than the offset, determine the second TCI state to be unknown; and complete the TCI state switching to the second TCI state within a first time period.

4. The first apparatus of claim 3, wherein the first apparatus is caused to: in accordance with a determination that the time window does not exceed the offset, determine the second TCI state to be known; and complete the TCI state switching to the second TCI state within a second time period, wherein the second time period is shorter than the first time period.

5. The first apparatus of claim 1 , wherein the validity timer corresponds to an offset relative to a time point when the indication of the pathloss offset corresponding to the second TCI state is received by the first apparatus or when the first apparatus is indicated with the pathloss offset corresponding to the second TCI state.

6. The first apparatus of claim 5, wherein the first apparatus is caused to: determine whether a time window between the time point and the reception of the TCI state switch command does not exceed the offset; and in accordance with a determination that the time window is larger than the offset, determine the second TCI state to be unknown; and complete the TCI state switching to the second TCI state within a first time period.

7. The first apparatus of claim 6, wherein the first apparatus is caused to: in accordance with a determination that the time window does not exceed the offset, determine the second TCI state to be known; and complete the TCI state switching to the second TCI state within a second time period, wherein the second time period is shorter than the first time period.

8. The first apparatus of any of claims 2-7, wherein the offset is set to a fixed value.

9. The first apparatus of any of claims 2-7, wherein the offset is a variable value.

10. The first apparatus of claim 9, wherein the offset is determined based on one of the following: a periodicity of an uplink reference signal, or a time period within which a TCI state is to be considered as being known after sending an uplink reference signal associated with the TCI state.11 . The first apparatus of any of claims 2-10, wherein the offset is indicated by the second apparatus via a radio resource control signaling.

12. The first apparatus of any of claims 1-11 , wherein the second TCI state indicated in the TCI state switch command is an uplink TCI state to be applied for a transmission reception point, TRP, that supports an uplink transmission and does not support a downlink transmission.

13. The first apparatus of any of claims 1 -12, wherein the indication of the pathloss offset refers to a configuration of the pathloss offset or an update of the pathloss offset.

14. The first apparatus of any of claims 1-13, the uplink reference signal transmission comprises at least one of the following: a sounding reference signal transmission,a demodulation reference signal transmission, or a phase tracking reference signal transmission.

15. A second apparatus comprising: at least one processor; and at least one memory storing instructions that, when executed by the at least one processor, cause the second apparatus at least to: configure, to a first apparatus, a second transmission configuration indicator, TCI, state associated with an uplink reference signal transmission; configure, to the first apparatus, a validity timer associated with determining whether the TCI state is considered as being known or unknown after a reception of a TCI state switch command indicating a TCI state switching from a first TCI state to the second TCI state; and transmit the TCI state switch command to the first apparatus.

16. The second apparatus of claim 15, wherein the validity timer corresponds to an offset relative to a time point when the uplink reference signal transmission corresponding to the second TCI state is transmitted by the first apparatus.

17. The second apparatus of claim 15, wherein the validity timer corresponds to an offset relative to a time point when an indication of a pathloss offset corresponding to the second TCI state is received by the first apparatus or when the first apparatus is indicated with the pathloss offset corresponding to the second TCI state.

18. The second apparatus of claim 16 or 17, wherein the offset is set to a fixed value.

19. The second apparatus of any of claims 16-18, wherein the offset is indicated by the second apparatus via a radio resource control signaling.

20. The second apparatus of any of claims 15-19, wherein the second TCI state indicated in the TCI state switch command is an uplink TCI state to be applied for a transmission reception point, TRP, that supports an uplink transmission and does not support a downlink transmission.

21. The second apparatus of claim 17, wherein the indication of the pathloss offset refers to a configuration of the pathloss offset or an update of the pathloss offset.

22. The second apparatus of any of claims 15-21 , the uplink reference signal transmission comprises at least one of the following: a sounding reference signal transmission, a demodulation reference signal transmission, or a phase tracking reference signal transmission.

23. A method comprising: receiving, from a second apparatus, a transmission configuration indicator, TCI, state switch command; and in accordance with a determination that the TCI state switch command indicates a TCI state switching from a first TCI state to a second TCI state, determining based on a validity timer associated with an uplink reference signal transmission corresponding to the second TCI state or with a reception of an indication of a pathloss offset corresponding to the second TCI state, the second TCI state to be known or unknown.

24. A method comprising: configuring, to a first apparatus, a second transmission configuration indicator, TCI, state associated with an uplink reference signal transmission; and configuring, to the first apparatus, a validity timer associated with determining whether the TCI state is considered as being known or unknown after a reception of a TCI state switch command indicating a TCI state switching from a first TCI state to the second TCI state. transmitting the TCI state switch command to the first apparatus.

25. A first apparatus comprising: means for receiving, from a second apparatus, a transmission configuration indicator, TCI, state switch command; means for in accordance with a determination that the TCI state switch command indicates a TCI state switching from a first TCI state to a second TCI state, determining based on a validity timer associated with an uplink reference signal transmission corresponding to the second TCI state or with a reception of an indication of a pathloss offset corresponding to the second TCI state, the second TCI state to be known or unknown.

26. A second apparatus comprising: means for configuring, to a first apparatus, a second transmission configuration indicator, TCI, state associated with an uplink reference signal transmission;means for configuring, to the first apparatus, a validity timer associated with determining whether the TCI state is considered as being known or unknown after a reception of a TCI state switch command indicating a TCI state switching from a first TCI state to the second TCI state; and means for transmitting the TCI state switch command to the first apparatus.

27. A computer readable medium comprising instructions stored thereon for causing an apparatus at least to perform the method of claim 25 or the method of claim 26.

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