Channel state information enhancement

Abstract

Example embodiments of the present disclosure are directed to channel state information (CSI) enhancement. In a method, a terminal apparatus receives, from a network apparatus, a CSI report configuration indicating a role for CSI reporting. In accordance with a determination that the role is a cluster head for group CSI reporting, the terminal apparatus transmits a full CSI report to the network apparatus based on the CSI report configuration. In accordance with a determination that the role is a cluster member for group CSI reporting, the terminal apparatus transmits a partial CSI report or refrain from transmitting a CSI report to the network apparatus based on the CSI report configuration.

Description

CHANNEL STATE INFORMATION ENHANCEMENTRELATED APPLICATION

[0001] This application claims priority to US provisional Application No. 63 / 717575 filed November 7, 2024, which is incorporated herein by reference in its entirety.FIELD

[0002] Various example embodiments of the present disclosure generally relate to the field of telecommunications and in particular, to methods, devices, apparatuses and computer readable storage medium for channel state information (CSI) enhancement.BACKGROUND

[0003] A communication network may serve as a facility that enables communications between two or more communication devices or provides communication devices access to a data network. A mobile or wireless communication network is one example of a communication network. The communication network may operate in accordance with standards such as those provided by Third Generation Partnership Project (3GPP) or European Telecommunications Standards Institute (ETSI). Examples of standards provided by 3GPP are the so-called 3GPP standards for cellular technology generations, such as 3GPP standards for 4G technology, 5G technology, 6G technology etc.SUMMARY

[0004] In a first aspect of the present disclosure, there is provided a terminal apparatus. The terminal apparatus comprises at least one processor; and at least one memory storing instructions that, when executed by the at least one processor, cause the terminal apparatus to: receive, from a network apparatus, a channel state information (CSI) report configuration indicating a role for CSI reporting; in accordance with a determination that the role is a cluster head for group CSI reporting, transmit a full CSI report to the network apparatus based on the CSI report configuration; and in accordance with a determination that the role is a cluster member for group CSI reporting, transmit a partial CSI report or refrain from transmitting a CSI report to the network apparatus based on the CSI report configuration.

[0005] In a second aspect of the present disclosure, there is provided a network apparatus. The network apparatus comprises at least one processor; and at least one memory storing instructions that, when executed by the at least one processor, cause the network apparatus to: determine a CSI commonality level between a terminal apparatus and one or more further terminal apparatuses; determine, for the terminal apparatus, a role for CSI reporting based on the CSI commonality level; and transmit, to the terminal apparatus, a CSI report configuration indicating the role for CSI reporting.

[0006] In a third aspect of the present disclosure, there is provided a method. The method comprises: receiving, from a network apparatus, a channel state information (CSI) report configuration indicating a role for CSI reporting; in accordance with a determination that the role is a cluster head for group CSI reporting, transmitting a full CSI report to the network apparatus based on the CSI report configuration; and in accordance with a determination that the role is a cluster member for group CSI reporting, transmitting a partial CSI report or refrain from transmitting a CSI report to the network apparatus based on the CSI report configuration.

[0007] In a fourth aspect of the present disclosure, there is provided a method. The method comprises: determining a CSI commonality level between a terminal apparatus and one or more further terminal apparatuses; determining, for the terminal apparatus, a role for CSI reporting based on the CSI commonality level; and transmitting, to the terminal apparatus, a CSI report configuration indicating the role for CSI reporting.

[0008] In a fifth aspect of the present disclosure, there is provided a terminal apparatus. The terminal apparatus comprises means for receiving, from a network apparatus, a channel state information (CSI) report configuration indicating a role for CSI reporting; means for in accordance with a determination that the role is a cluster head for group CSI reporting, transmitting a full CSI report to the network apparatus based on the CSI report configuration; and means for in accordance with a determination that the role is a cluster member for group CSI reporting, transmitting a partial CSI report or refrain from transmitting a CSI report to the network apparatus based on the CSI report configuration.

[0009] In a sixth aspect of the present disclosure, there is provided a network apparatus. The network apparatus comprises means for determining a CSI commonality level between a terminal apparatus and one or more further terminal apparatuses; means for determining, for the terminal apparatus, a role for CSI reporting based on the CSIcommonality level; and means for transmitting, to the terminal apparatus, a CSI report configuration indicating the role for CSI reporting.

[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 or the fourth aspect.

[0011] In an eighth aspect of the present disclosure, there is provided a terminal apparatus. The terminal apparatus comprises at least one processor; and at least one memory storing instructions that, when executed by the at least one processor, cause the terminal apparatus to: receive, from a network apparatus, a channel state information (CSI) report configuration indicating at least one of a CSI parameter to be reported or a CSI parameter to be not reported; determine, based on the CSI report configuration, a first CSI parameter to be reported and a second CSI parameter to be not reported; determine, whether the second CSI parameter is associated with a determination of the first CSI parameter; in accordance with a determination that the second CSI parameter is associated with the determination of the first CSI parameter, determine the first CSI parameter based on a channel measurement by determining the second CSI parameter, or determine the first CSI parameter based on a CSI calculation capability of the terminal apparatus and a channel measurement without determining the second CSI parameter; and transmit, to the network apparatus, a CSI report including the first CSI parameter and not including the second CSI parameter.

[0012] In a ninth aspect of the present disclosure, there is provided a network apparatus. The network apparatus comprises at least one processor; and at least one memory storing instructions that, when executed by the at least one processor, cause the network apparatus to: determine, for a terminal apparatus, a channel state information (CSI) report configuration based on a CSI commonality level between the terminal apparatus and one or more further terminal apparatuses, the CSI report configuration indicating at least one of a CSI parameter to be reported or a CSI parameter to be not reported; transmit the CSI report configuration to the terminal apparatus; and receive a CSI report from the terminal apparatus.

[0013] In a tenth aspect of the present disclosure, there is provided a method. The method comprises: receiving, from a network apparatus, a channel state information (CSI)report configuration indicating at least one of a CSI parameter to be reported or a CSI parameter to be not reported; determining, based on the CSI report configuration, a first CSI parameter to be reported and a second CSI parameter to be not reported; determining, whether the second CSI parameter is associated with a determination of the first CSI parameter; in accordance with a determination that the second CSI parameter is associated with the determination of the first CSI parameter, determining the first CSI parameter based on a channel measurement by determining the second CSI parameter, or determining the first CSI parameter based on a CSI calculation capability of the terminal apparatus and a channel measurement without determining the second CSI parameter; and transmitting, to the network apparatus, a CSI report including the first CSI parameter and not including the second CSI parameter.

[0014] In an eleventh aspect of the present disclosure, there is provided a method. The method comprises: determining, for a terminal apparatus, a channel state information (CSI) report configuration based on a CSI commonality level between the terminal apparatus and one or more further terminal apparatuses, the CSI report configuration indicating at least one of a CSI parameter to be reported or a CSI parameter to be not reported; transmitting the CSI report configuration to the terminal apparatus; and receiving a CSI report from the terminal apparatus.

[0015] In a twelfth aspect of the present disclosure, there is provided a terminal apparatus. The terminal apparatus comprises means for receiving, from a network apparatus, a channel state information (CSI) report configuration indicating at least one of a CSI parameter to be reported or a CSI parameter to be not reported; means for determining, based on the CSI report configuration, a first CSI parameter to be reported and a second CSI parameter to be not reported; means for determining, whether the second CSI parameter is associated with a determination of the first CSI parameter; in accordance with a determination that the second CSI parameter is associated with the determination of the first CSI parameter, means for determining the first CSI parameter based on a channel measurement by determining the second CSI parameter, or means for determining the first CSI parameter based on a CSI calculation capability of the terminal apparatus and a channel measurement without determining the second CSI parameter; and means for transmitting, to the network apparatus, a CSI report including the first CSI parameter and not including the second CSI parameter.

[0016] In a thirteenth aspect of the present disclosure, there is provided a network apparatus. The network apparatus comprises means for determining, for a terminal apparatus, a channel state information (CSI) report configuration based on a CSI commonality level between the terminal apparatus and one or more further terminal apparatuses, the CSI report configuration indicating at least one of a CSI parameter to be reported or a CSI parameter to be not reported; means for transmitting the CSI report configuration to the terminal apparatus; and means for receiving a CSI report from the terminal apparatus.

[0017] In a fourteenth 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 tenth or eleventh aspect.

[0018] In a fifteenth aspect of the present disclosure, there is provided a terminal apparatus. The terminal apparatus comprises at least one processor; and at least one memory storing instructions that, when executed by the at least one processor, cause the terminal apparatus to: receive, from a network apparatus, a channel state information (CSI) report configuration indicating a reference CSI; determine, based on the CSI report configuration, a representation format of a CSI report, wherein the representation format indicates at least one CSI parameter to be reported and at least one format corresponding to the at least one parameter to be reported; generate the CSI report based on the determined representation format and a channel measurement; and transmit the CSI report to the network apparatus.

[0019] In a sixteenth aspect of the present disclosure, there is provided a network apparatus. The network apparatus comprises at least one processor; and at least one memory storing instructions that, when executed by the at least one processor, cause the network apparatus to: determine a channel state information (CSI) report configuration indicating a reference CSI; transmit the CSI report configuration to a terminal apparatus; and receive, from the terminal apparatus, a CSI report in a representation format associated with the CSI report configuration.

[0020] In a seventeenth aspect of the present disclosure, there is provided a method. The method comprises: receiving, from a network apparatus, a channel state information (CSI) report configuration indicating a reference CSI; determining, based on the CSIreport configuration, a representation format of a CSI report, wherein the representation format indicates at least one CSI parameter to be reported and at least one format corresponding to the at least one parameter to be reported; generating the CSI report based on the determined representation format and a channel measurement; and transmitting the CSI report to the network apparatus.

[0021] In an eighteenth aspect of the present disclosure, there is provided a method. The method comprises: determining a channel state information (CSI) report configuration indicating a reference CSI; transmitting the CSI report configuration to a terminal apparatus; and receiving, from the terminal apparatus, a CSI report in a representation format associated with the CSI report configuration.

[0022] In a nineteenth aspect of the present disclosure, there is provided a terminal apparatus. The terminal apparatus comprises means for receiving, from a network apparatus, a channel state information (CSI) report configuration indicating a reference CSI; means for determining, based on the CSI report configuration, a representation format of a CSI report, wherein the representation format indicates at least one CSI parameter to be reported and at least one format corresponding to the at least one parameter to be reported; means for generating the CSI report based on the determined representation format and a channel measurement; and means for transmitting the CSI report to the network apparatus.

[0023] In a twentieth aspect of the present disclosure, there is provided a network apparatus. The network apparatus comprises means for determining a channel state information (CSI) report configuration indicating a reference CSI; means for transmitting the CSI report configuration to a terminal apparatus; and means for receiving, from the terminal apparatus, a CSI report in a representation format associated with the CSI report configuration.

[0024] In a twenty-first 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 seventeenth or eighteenth aspect.

[0025] It is to be understood that the Summary section is not intended to identify key or essential features 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 willbecome easily comprehensible through the following description.BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Some example embodiments will now be described with reference to the accompanying drawings, where:

[0027] FIG. 1 illustrates example communication environment in which example embodiments of the present disclosure can be implemented;

[0028] FIG. 2 illustrates a signaling flow of an example process for CSI enhancement in accordance with some example embodiments of the present disclosure;

[0029] FIG. 3 illustrates a schematic diagram of an example process for CSI reporting clustering in accordance with some example embodiments of the present disclosure;

[0030] FIG. 4A, 4B and 4C illustrate examples of a CSI commonality in accordance with some example embodiments of the present disclosure;

[0031] FIG. 5 illustrates a signaling flow of an example process for group CSI reporting in accordance with some example embodiments of the present disclosure;

[0032] FIG. 6 illustrates a signaling flow of an example process for CSI reporting based on a reference CSI in accordance with some example embodiments of the present disclosure;

[0033] FIG. 7 illustrates a signaling flow of an example process for CSI reporting based on a specifically indicated CSI parameter in accordance with some example embodiments of the present disclosure;

[0034] FIG. 8 illustrates a flowchart of a method implemented at a terminal apparatus in accordance with some example embodiments of the present disclosure;

[0035] FIG. 9 illustrates a flowchart of a method implemented at a network apparatus in accordance with some example embodiments of the present disclosure;

[0036] FIG. 10 illustrates another flowchart of a method implemented at a terminal apparatus in accordance with some example embodiments of the present disclosure;

[0037] FIG. 11 illustrates another flowchart of a method implemented at a network apparatus in accordance with some example embodiments of the present disclosure;

[0038] FIG. 12 illustrates another flowchart of a method implemented at a terminal apparatus in accordance with some example embodiments of the present disclosure;

[0039] FIG. 13 illustrates another flowchart of a method implemented at a network apparatus in accordance with some example embodiments of the present disclosure;

[0040] FIG. 14 illustrates a simplified block diagram of a device that is suitable for implementing example embodiments of the present disclosure; and

[0041] FIG. 15 illustrates a block diagram of an example computer readable medium in accordance with some example embodiments of the present disclosure.

[0042] Throughout the drawings, the same or similar reference numerals represent the same or similar element.DETAILED DESCRIPTION

[0043] 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.

[0044] 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.

[0045] 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 particular feature, 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.

[0046] It shall be understood that although the terms “first,” “second,”..., etc. in frontof 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.

[0047] 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.

[0048] 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.

[0049] 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.

[0050] 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 variousfunctions) 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.

[0051] 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.

[0052] 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-IoT) 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 (1G), 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 type 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.

[0053] 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 referredto as a gNB), a Remote Radio Unit (RRU), a radio header (RH), a remote radio head (RRH), a relay, an Integrated Access and Backhaul (IAB) 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 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 nexthop IAB node.

[0054] As used herein, the term “core network function” may be implemented as a core network entity that includes a combination of hardware processing circuit and software and / or firmware comprising machine-readable instructions, or software comprising machine-readable instructions that are executable by at least one processor of hardware processing circuit of an apparatus. A hardware processing circuit includes at least one processor and at least one memory storing machine-readable instructions that are executable by the at least one processor of the hardware processing circuit. A processor includes any or some combination of an accelerator, a microprocessor, a core of a multicore microprocessor, a microcontroller, a programmable integrated circuit, a programmable gate array, a digital signal processor, a central processing unit, a graphic processing unit, a tensor processing unit. Memory includes any or some combination of volatile or non-volatile memory (e.g., a flash memory, cache, a random-access memory (RAM), and / or a read-only memory (ROM)). The memory stores the machine-readable instructions of the software and / or firmware for execution by the at least one processor of the hardware processing circuit. The machine-readable instructions are executable by the at least one processor of the hardware processing circuit cause the hardware processing circuit to perform the actions or operations of the methods described herein. For example, the session management function described herein may be implemented as a session management entity and the session management policy control function described herein may be implemented as a session management policy control entity, respectively.

[0055] 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 mayalso 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.

[0056] 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.

[0057] With the development of communication technologies, CSI enhancements, especially CSI feedback / reporting enhancements are under investigation. For example, 5G and beyond systems that support massive Multiple-Input Multiple- Output (MIMO) technology require carefully considering the mechanism and the quality of the CSIacquired at the UE or at the BS for determining the MIMO precoder to apply for transmitting in the downlink (DL) direction.

[0058] In Frequency Division Duplex (FDD) systems, the BS may receive a CSI report containing information about the downlink channel measured at the UE upon receiving DE CSI reference signals (RS). Based on the CSI feedback (report), the BS may determine from a predefined codebook a set of precoding matrices used for the DL transmission. In Time Division Duplex (TDD) systems, thanks to the reciprocity between DL and UL channels, the BS may estimate the downlink channel and acquire the CSI information based on its estimation of the uplink channel with the sounding reference signals (SRS) transmitted from the UE in the uplink direction. Then, the BS may autonomously calculate the precoding matrix to obtain eigenvector beamforming matrices.

[0059] The CSI report may include fields / parameters / reporting quantities such as, including but not limited to, a precoding matrix indicator (PMI), a channel quality indicator (CQI), a rank indicator (RI), time domain channel proprieties (TDCP), and / or a reference signal received power (RSRP). Brief introduction of some example CSI parameters is provided below for illustration only.

[0060] PMI may be the most important CSI quantity / parameter of the set of information components contained in the CSI report. It may help the BS to select appropriate precoding weights for data transmission. Briefly speaking, the UE may select the CSI-RS that gives the best signal-to-interference-plus-noise ratio (SINR), and then obtain a corresponding PMI from a codebook and report the PMI to the BS. The codebook may be a set of precoding matrices. In 5G, two types of codebooks are defined: Type I and Type II with different respective evolutions across the latest releases.

[0061] RI may be used to report the number of independent communication channels or spatially orthogonal streams, which may help the BS to assess how well multiple antennas work to transmit simultaneous data toward the UE.

[0062] CQI may be used to indicate channel quality to the BS. It may have a value between 0 to 15, indicating the signal-to-noise ratio (SNR) level related to the measured effective channel conditions. Based on the CQI, a modulation and coding scheme (MCS) may be selected during MIMO scheduling.

[0063] TDCP may be used to indicate channel variation over time, e.g., how fast thechannel varies. This may be of pivotal importance for the BS. In 3GPP Release-18 enhancements of 5G-advanced, TDCP feedback that indicates the degree of timevariability of the channel is being standardized. This may help the BS in many aspects, e.g., switching between Type-I and Type-II precoding at different UE speed conditions.

[0064] Recently, some solutions have been proposed to investigate coordination between the BS and UEs to improve the CSI feedback. For instance, in some solutions, exchange of CSI between UEs (e.g., via sidelink) is proposed to reduce CSI feedback overhead by letting one UE in the group of UEs to process the CSIs received from other UEs and report the processed CSI to the network (NW). However, it is unclear how the NW may be able to control the process of the UE responsible for receiving the CSIs from other UEs in the group. In addition, the NW may not be able to have control over the optimization of the UE feedback. In other words, signaling aspects are not properly considered, as the NW node is currently the one that configures the UE for CSI measurement and reporting.

[0065] In some other sidelink-based solutions, CSI summarization of the group of UEs is proposed to reduce the CSI feedback overhead. For example each UE within a coordination group may perform CSI measurement and one of the UEs, i.e., the Head UE, reports the CSI on behalf of each UE in the coordination group. Alternatively, only one UE performs CSI measurement and reports on behalf of UEs within a coordination group. In both cases, the only one to transmit for the coordination group is the head UE. However, it is unclear how a member UE or secondary UE reports its own CSI when partial CSI updates are needed without fully relying on the resources of the head UE and a proper coordination from the NW side.

[0066] In order to solve at least part of the above problems or other potential problems, several solutions for CSI enhancements according to embodiments of the present disclosure are proposed.

[0067] In one solution, a terminal apparatus receives, from a network apparatus, a CSI report configuration indicating a role for CSI reporting. If the role is a cluster head for group CSI reporting, the terminal apparatus transmits a full CSI report to the network apparatus based on the CSI report configuration. If the role is a cluster member for group CSI reporting, the terminal apparatus transmits a partial CSI report or refrains from transmitting a CSI report to the network apparatus based on the CSI report configuration.

[0068] With this solution, a NW / BS-driven CSI enhancement can be achieved based on the CSI report configuration indicating the role for CSI reporting. The network apparatus can control the optimization of the UE CSI feedback by indicating the role for CSI reporting to the terminal apparatus. Moreover, behaviors of both the head UE and the member UE can be configured based on the CSI report configuration.

[0069] In another solution, a terminal apparatus receives, from a network apparatus, a CSI report configuration indicating at least one of a CSI parameter to be reported or a CSI parameter to be not reported. Based on the CSI report configuration, the terminal apparatus determines a first CSI parameter to be reported and a second CSI parameter to be not reported and determines whether the second CSI parameter is associated with a determination of the first CSI parameter. If the second CSI parameter is associated with the determination of the first CSI parameter, the terminal apparatus determines the first CSI parameter based on a channel measurement by determining the second CSI parameter, or determines the first CSI parameter based on a CSI calculation capability of the terminal apparatus and a channel measurement without determining the second CSI parameter. The terminal apparatus further transmits to the network apparatus a CSI report including the first CSI parameter and not including the second CSI parameter.

[0070] With this solution, the NW / BS-driven CSI enhancement can also be achieved based on the CSI report configuration indicating the CSI parameter to be reported and / or the CSI parameter to be not reported. The network apparatus can control the optimization of the UE CSI feedback by indicating to the terminal apparatus a specific CSI parameter to be reported and / or a specific CSI parameter to be not reported.

[0071] In a further solution, a terminal apparatus receives, from a network apparatus, a CSI report configuration indicating a reference CSI. Based on the CSI report configuration, the terminal apparatus determines a representation format of a CSI report and the representation format indicates at least one CSI parameter to be reported and at least one format corresponding to the at least one parameter to be reported. The terminal apparatus further generates the CSI report based on the determined representation format and a channel measurement and transmits the CSI report to the network apparatus.

[0072] With this solution, the NW / BS-driven CSI enhancement can also be achieved based on the CSI report configuration indicating the reference CSI. The network apparatus can control the optimization of the UE CSI feedback by indicating the referenceCSI to the terminal apparatus for the terminal apparatus to generate a corresponding CSI report.

[0073] Several solutions of the present disclosure have been briefly described. Principle and implementations of the present disclosure will be described in detail below with reference to the accompany drawings. It will be appreciated that acts, steps, processes, and / or flowcharts illustrated in the drawings are only examples without suggesting any limitation. For example, the steps may be performed in any suitable manner. The steps as illustrated in one or more drawings may be selectively performed in an actual implementation. Moreover, example embodiments described with reference to the drawings may be implemented separately or combined in any suitable manner. For example, one or more example embodiments shown in a single drawing may be combined with one or more example embodiments shown in one or more other drawings.

[0074] Reference is first made to FIG. 1. FIG. 1 shows an example communication environment 100 in which example embodiments of the present disclosure may be implemented. The network communication 100 comprises one or more network apparatuses such as a network apparatus 110, and one or more terminal apparatuses, such as a terminal apparatus 120-1, a terminal apparatus 120-2 and a terminal apparatus 120- 3. For purpose of discussion, the terminal apparatus 120-1, terminal apparatus 120-2 and terminal apparatus 120-3 may be collectively referred to as the terminal apparatuses 120 or individually referred to as the terminal apparatus 120.

[0075] In some example embodiments, a communication direction from the network apparatus 110 to the terminal apparatus 120 is referred to as a downlink (DL), and a communication direction from the terminal apparatus 120 to the network apparatus 110 is referred to as an uplink (UL). In DL, the network apparatus 110 is a transmitting (TX) apparatus (or a transmitter) and the terminal apparatus 120 is a receiving (RX) apparatus (or a receiver). In UL, the terminal apparatus 120 is a TX apparatus (or a transmitter) and the network apparatus 110 is a RX apparatus (or a receiver).

[0076] Communications in the communication environment 100 may be implemented according to any proper communication protocol(s), comprising, but not limited to, cellular communication protocols, 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, thecommunication 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.

[0077] In the following, for the purpose of illustration, some example embodiments may be described with the terminal apparatus 120 operating as a terminal device. However, in some example embodiments, operations described in connection with a terminal device may be implemented at a network device or other device, and operations described in connection with a network device may be implemented at a terminal device or other device.

[0078] It is to be understood that the number of apparatuses 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 apparatuses configured to implement example embodiments of the present disclosure. Although not shown, it would be appreciated that one or more additional apparatuses may be deployed in the communication environment 100. Although illustrated as a base station, the network apparatus 110 may be or may be comprised in any other suitable network device. Although illustrated as a UE, the terminal apparatus 120 may be or may be comprised in any other suitable terminal device.

[0079] With reference to FIG. 1, in some embodiments of the present disclosure, the terminal apparatus 120 receives, from the network apparatus 110, a CSI report configuration indicating a role for CSI reporting. If the role is a cluster head for group CSI reporting, the terminal apparatus 120 transmits a full CSI report to the network apparatus based on the CSI report configuration. If the role is a cluster member for group CSI reporting, the terminal apparatus 120 transmits a partial CSI report or refrains from transmitting a CSI report to network apparatus 110 based on the CSI report configuration.

[0080] In some embodiments of the present disclosure, the terminal apparatus 120 receives, from the network apparatus 110, a CSI report configuration indicating at least one of a CSI parameter to be reported or a CSI parameter to be not reported. Based on theCSI report configuration, the terminal apparatus 120 determines a first CSI parameter to be reported and a second CSI parameter to be not reported and determines whether the second CSI parameter is associated with a determination of the first CSI parameter. If the second CSI parameter is associated with the determination of the first CSI parameter, the terminal apparatus 120 determines the first CSI parameter based on a channel measurement by determining the second CSI parameter, or determines the first CSI parameter based on a CSI calculation capability of the terminal apparatus and a channel measurement without determining the second CSI parameter. The terminal apparatus 120 further transmits to the network apparatus 110 a CSI report including the first CSI parameter and not including the second CSI parameter.

[0081] In some embodiments of the present disclosure, the terminal apparatus 120 receives, from the network apparatus 110, a CSI report configuration indicating a reference CSI. Based on the CSI report configuration, the terminal apparatus 120 determines a representation format of a CSI report and the representation format indicates at least one CSI parameter to be reported and at least one format corresponding to the at least one parameter to be reported. The terminal apparatus 120 further generates the CSI report based on the determined representation format and a channel measurement and transmits the CSI report to the network apparatus 110.

[0082] FIG. 2 illustrates a signaling flow of an example process 200 for CSI enhancement in accordance with some example embodiments of the present disclosure. As illustrated in FIG. 2, the process 200 involves a terminal apparatus 210 and a network apparatus 220. The terminal apparatus 210 may be an example of the terminal apparatus 120 in FIG. 1. The network apparatus 220 may be an example of the network apparatus 110 in FIG. 1.

[0083] In the process 200, the network apparatus 220 determines 250 a role for CSI reporting for the terminal apparatus 210. The network apparatus 220 transmits 252, to the terminal apparatus 210, a CSI report configuration indicating the role for CSI reporting. The terminal apparatus 210 receives 254 the CSI report configuration.

[0084] The role of CSI reporting indicated by the CSI report configuration may indicate at least two types of roles. The first type is a role for a cluster member (may be also referred to as a secondary UE) for group CSI reporting and the second type is a role for a cluster head for group CSI reporting. Example processes 260 and 270 are illustrated inFIG. 2 for further discussion.

[0085] In the example process 260, the terminal apparatus 210 determines 262 that the role is the cluster member for group CSI reporting. Based on this determination, the terminal apparatus 210 may transmit 264 a partial CSI report to the network apparatus 220 and the network apparatus 220 may receive 266 the partial CSI report. Alternatively, the terminal apparatus 210 may refrain 268 from transmitting a CSI report to the network apparatus 220.

[0086] In the example process 270, the terminal apparatus 210 determines 272 that the role is a cluster head for group CSI reporting. Based on this determination, the terminal apparatus 210 transmits 274 a full CSI report to the network apparatus 220 based on the CSI report configuration and the network apparatus 220 may receive 276 the full CSI report.

[0087] In some embodiments, the full CSI report or the partial CSI report comprises at least a part of one of: a precoding matrix indicator (PMI), a channel quality indicator (CQI), a rank indicator (RI), time domain channel proprieties (TDCP), or a reference signal received power (RSRP).

[0088] With the process 200, based on the indicated role for CSI reporting, the terminal apparatus 210 may transmit a full CSI report or a partial CSI report, or refrain from transmit a CSI report to the network apparatus 220, such that the CSI feedback overhead can be reduced.

[0089] In some embodiments, the terminal apparatus 210 may determine the partial CSI report by refraining from including a common CSI parameter between the terminal apparatus and a further terminal apparatus in a same cluster. In other words, the partial CSI report includes no common CSI parameter such that transmitting the partial CSI report can reduce the signaling overhead compared to transmitting the full CSI report.

[0090] The common CSI parameter between the terminal apparatus and the further terminal apparatus may be associated with a same CSI parameter value or different CSI parameter values satisfying a commonality condition. For example, the commonality condition may specify a range for a CSI parameter. If two terminal apparatuses have respective CSI parameter values of the CSI parameter and the two values are within the range, the CSI parameter may be considered as a common CSI parameter between the twoterminal apparatuses. The commonality condition may vary depending on the CSI parameter. For example, the CSI parameter may be a matrix, then the commonality condition may be associated with differences between element values of the matrix. The scope of the present disclosure is not limited in this regard.

[0091] If determining to transmit the partial CSI report including no common CSI parameter, i.e., determining that its role is the cluster member for group CSI reporting, the terminal apparatus 210 may generate / determine the partial CSI report in various ways.

[0092] In some embodiments, the terminal apparatus 210 may receive a reference CSI from the network apparatus 220 and determine the partial CSI report based on the reference CSI. The reference CSI may be received also in the CSI report configuration or received in a different message. The reference CSI may indicate information on how to report a CSI and / or what to report. The terminal apparatus 210 may generate the partial CSI report by using the reference CSI as a reference. Details of CSI reporting based on the reference CSI (also referred to as a soft mode) will be described with reference to FIG. 6.

[0093] In some embodiments, the reference CSI may comprise a reference CSI parameter. Alternatively or additionally, the reference CSI may comprise information to be reported in association with a CSI parameter. For example, the reference CSI may indicate indexes of a set of beams, a set of sub-bands, and / or a set of delay taps. Then, the partial CSI report may include coefficients corresponding to these indexes. Alternatively or additionally, the reference CSI may comprise a part of a CSI parameter. For example, the CSI parameter PMI may be split into beams, delay taps and spacefrequency coefficients, and the reference CSI may include part(s) of them. Alternatively or additionally, the reference CSI may comprise a full CSI report. As an example, the full CSI report may be a CSI report that a cluster head transmits to the network apparatus 220 and the network apparatus 220 transmits to the terminal apparatus 210. The cluster head and the terminal apparatus 210 may belong to a same cluster and the terminal apparatus 210 may be a cluster member. As another example, the full CSI report may be a predefined or standardized CSI report, or a NW configured CSI report.

[0094] Additionally or alternative to the reference CSI, the terminal apparatus 210 may receive, from the network apparatus 220, a CSI parameter to be reported and / or a CSI parameter to be not reported. The CSI parameter to be reported and / or the CSI parameterto be not reported is also referred to as the specifically indicated CSI parameter in the present disclosure. Then the terminal apparatus 210 may determine the partial CSI report based on the CSI parameter to be reported and / or the CSI parameter to be not reported. The specifically indicated CSI parameter to be reported or to be not reported may be any CSI parameter (may be also referred to as CSI reporting quantity) or a part of CSI parameter / reporting quantity. The specifically indicated CSI parameter may be received also in the CSI report configuration or received in a different message.

[0095] Based on the specifically indicated CSI parameter to be reported and / or the CSI parameter to be not reported, the terminal apparatus 210 may determine what CSI parameter(s) to be reported in the partial CSI report. As an example, the CSI parameter indicated to be not reported may be removed from a default list of CSI parameters to be reported in the full CSI report. As another example, only the CSI parameter(s) indicated to be reported is included in the partial CSI report. Further details of CSI reporting based on a specifically indicated CSI parameter (also referred to as a hard mode herein) will be described with reference to FIG. 7 in the following description.

[0096] In some embodiments, the terminal apparatus 210 may further receive, from the network apparatus 220, a cluster indication of a cluster which the terminal apparatus 210 belongs to. The cluster indication may indicate a cluster type and / or a cluster identifier. The cluster indication may indicate that the cluster which the terminal apparatus 210 belongs to is a fully common cluster, a partially common cluster, or a fully non-common cluster. The cluster indication may be received also in the CSI report configuration or received in a different message. In some embodiments, the cluster indication may be indicated in association with the role indicated in the CSI report configuration. Alternatively, the cluster indication may be explicitly or implicitly indicated by the role. For example, the role may be a cluster member in a fully common cluster.

[0097] The fully common cluster may refer to a cluster where a terminal apparatus shares a fully common CSI with a further terminal apparatus, i.e., each CSI parameter is the common CSI parameter between the terminal apparatuses. The fully non-common cluster may refer to a cluster where a terminal apparatus shares no common CSI parameter with a further terminal apparatus. The partially common cluster may refer to a cluster where a terminal apparatus shares one or more common CSI parameters with a further terminal apparatus and also has one or more non-common CSI parameters relative to the furtherterminal apparatus. In other words, a portion of CSI parameters of the terminal apparatus is common between the terminal apparatus and a further terminal apparatus.

[0098] Based on the cluster indication and the role, the terminal apparatus 210 may determine what to report, i.e., to transmit the full CSI report, partial CSI report or avoid transmitting a CSI report.

[0099] In some embodiments, if determining that the cluster is the fully common cluster and the role is the cluster member for group CSI reporting, the terminal apparatus 210 may determine to refrain from transmitting a CSI report to the network apparatus 220. In this case, the cluster head in the fully common cluster may transmit a full CSI report for the cluster member such that the CSI feedback overhead can be reduced.

[0100] In some embodiments, if determining that the cluster is the partially common cluster and the role is the cluster member for group CSI reporting, the terminal apparatus 210 may determine to transmit the partial CSI report to the network apparatus 220. In this case, one or more common CSI parameters between the terminal apparatus 210 and the cluster head may be prevented from being reported, such that the CSI feedback overhead can be reduced.

[0101] In some embodiments, if determining that the cluster is the fully non-common cluster and the role is for non-common CSI reporting, the terminal apparatus 210 may determine to transmit a full CSI report to the network apparatus.

[0102] It is to be noted that, the role of the terminal apparatus 210 (and the cluster indication) may change. As an example, the role may be reconfigured based on a trigger, timer, and / or periodicity. As another example, the role may change due to a change of the terminal apparatus 210.

[0103] In some embodiments, in each cluster the head UE may be re-selected, and the UE group may be redefined if needed. This is useful in order to better select the best representative head UE for the cluster and to update the secondary UEs configurations according to the ever changing channel conditions.

[0104] In some embodiments, the role of the terminal apparatus 210 may change from a cluster head to a cluster member or a cluster member to a cluster head. The cluster head and the cluster member may be associated with a same cluster or different clusters. As an example, in a same fully common cluster, the terminal apparatus 210 may serve as acluster member for a time period and then switch to serving as a cluster head for a time period. As another example, the terminal apparatus 210 may serve as a cluster head of a first cluster and then switch to serving as a cluster member of a different cluster. In some embodiments, the role may change from a first cluster head to a second cluster head or change from a first cluster member to a second cluster member.

[0105] In some embodiments, the terminal apparatus 210 may receive a role change indication of a change of the role from a first cluster head of a first cluster to a first cluster member. The first cluster member may be associated with the first cluster or a further cluster different from the first cluster. Alternatively, the terminal apparatus 210 may receive the role change indication of a change of the role from the first cluster head to a second cluster head associated with a second cluster different from the first cluster.

[0106] In some embodiments, the terminal apparatus 210 may receive a role change indication of a change of the role from a first cluster member of a first cluster to a second cluster member associated with a second cluster different from the first cluster. Alternatively, the terminal apparatus 210 may receive a role change indication of a change of the role from the first cluster member to a cluster head associated with the first cluster or a second cluster different from the first cluster.

[0107] As discussed above, the role of the terminal apparatus 210 is determined by the network apparatus 220. At network side (not illustrated in FIG. 1), the network apparatus 220 may determine a CSI commonality level between the terminal apparatus 210 and one or more further terminal apparatuses and determine a role for CSI reporting for the terminal apparatus 210 based on the CSI commonality level. The CSI commonality level may indicate that various terminal apparatuses share an at least partially common CSI or share no common CSI.

[0108] In some embodiments, if determining that no common CSI parameter is present between the terminal apparatus and the one or more further terminal apparatuses, the network apparatus 220 may determine that the terminal apparatus and the one or more further terminal apparatuses share no common CSI. In this case, the network apparatus 220 may determine that the role for the terminal apparatus 210 is a role for non-common CSI reporting configured to transmit a full CSI report.

[0109] In some embodiments, if determining that a common CSI parameter is present between the terminal apparatus and the one or more further terminal apparatuses, thenetwork apparatus 220 may determine that the terminal apparatus and the one or more further terminal apparatuses share an at least partially common CSI. In this case, the network apparatus 220 may determine that the role for the terminal apparatus 210 is one of: a cluster head for group CSI reporting configured to transmit a full CSI report, a cluster member for group CSI reporting configured to transmit a partial CSI report, or a cluster member for group CSI reporting configured to refrain from transmitting a CSI report.

[0110] The network apparatus 220 may determine whether the terminal apparatus 210 is the cluster head or the cluster member based on at least one of: RSRP values of the terminal apparatus 210 and the one or more further terminal apparatuses, distances between the terminal apparatus 210 and the one or more further terminal apparatuses, distances between the terminal apparatus 210 and the network apparatus 220, or a rotation rule for a cluster.

[0111] The terminal apparatus 210 role could be also selected based on predefined UE capabilities or characteristics, for example, UE power status or processing units occupation for CSI. The scope of the present disclosure is not limited in this regard.

[0112] As an example, a cluster head may be identified based on the RSRP that is reported to the network apparatus 220. The network apparatus 220 may select the terminal apparatus with the highest RSRP as the cluster head because this will reduce the energy consumed in transmitting the CSI feedback in the uplink. In addition, this will increase the possibility of avoiding any feedback transmission errors due to a reduced coverage.

[0113] As another example, a terminal apparatus closest to a cluster’s centroid may be selected as the cluster head, e.g., in a case where a specific clustering algorithm (e.g., k- means) is applied for clustering the terminal apparatuses. Similarly, the cluster head may be selected based on the closest Euclidean distance from the network apparatus 220.

[0114] As yet another example, the network apparatus 220 may schedule the UEs to report in a round-robin fashion. For example, within a cluster, at each round a new UE can send the CSI report. Assume a number of N UEs in a group, then the first selected UE may re-transmit the CSI report after N CSI-RS occasions.

[0115] In some embodiments, the network apparatus 220 may determine the CSI commonality level based on at least one of: historical CSIs reported from the terminalapparatus and the one or more further terminal apparatuses, instantaneous CSIs reported from the terminal apparatus and the one or more further terminal apparatuses, channel characteristics of the terminal apparatus and the one or more further terminal apparatuses, locations of the terminal apparatus and the one or more further terminal apparatuses, or mobility of the terminal apparatus and the one or more further terminal apparatuses.

[0116] As an example, received historical CSIs or instantaneous CSIs may be used to test the correlation between the channel of two or more UEs. For example, PMI / CQI values of two or more UEs may be compared by means of the cosine similarity or mean- squared-error (MSE) metric applied in the channel or resulting precoding matrices. UEs in close spatial proximity may show a high correlation between the channel of UE1 and the channel of UE2. Therefore, UE1 and UE2 may be determined as sharing one or more common CSI parameters and added to a same CSI reporting group. In some examples, more than two UEs may be evaluated, and one or more UE groups may be formed based on the correlation values between pair of UEs.

[0117] Channel characteristics to determine the CSI commonality level can be determined from the CSI feedback but also from other sources, for example, information obtained from other reference signals like SRS from uplink sent by each UE, if some degree of channel reciprocity is assumed.

[0118] Further details of determining the CSI commonality level and the clustering process will be described with reference to FIG. 3 and FIG. 4A, 4B and 4C.

[0119] FIG. 3 illustrates a schematic diagram of an example process 300 for CSI reporting clustering in accordance with some example embodiments of the present disclosure. The process 300 may be implemented at the network apparatus 110 in FIG. 1. For the purpose of discussion, the process 300 will be described with reference to FIG. 1.

[0120] As illustrated in FIG. 3, at a time instance 1=1, the process 300 starts. At step 310, the NW (e.g., the network apparatus 110) receives CSIs (e.g., PMI, CQI and so on) from K UEs (e.g., the terminal apparatuses 120) present in the network. At step 315, the NW then compares the CSIs from the K UEs. For example, for an z'-th UE and a j-th UE in the K UEs, the NW determines whether CSI (fa) is equal to CSI (fa).

[0121] If so, the NW may select the UEs that share “a common CSI” and adds them in one cluster p G P (C.l). The number of the selected UEs share the common CSI isdenoted as Jp< K. In some embodiments, the NW receives the CSIs (PMI, CQI, RI, TDCP, etc.) from each UE present in the network. The NW determines the UEs that have same or similar CSI parameters with some tolerance threshold or some conditions of similarity to be met. For example, the NW may compare the CQIs, PMIs of each UE with other UEs. Then UEs that have similar CSI parameters can be put in one cluster with a cluster head which transmits a common CSI part.

[0122] The NW may select the others with non-common CSIs in a cluster denoted as “cluster zero” (C.2). The number of the selected UEs share no common CSI is denoted as Jo < Sp Jp-

[0123] At step 320, in cluster p G P (C.l), the NW may select a cluster head for the cluster p, denoted as CH p at periodic intervals. For example, the cluster head of UEs sharing “a common CSI” into a cluster, C.l, may be re-selected in specified periodical time windows depending on the network capabilities or UE dynamics into the cell. Then, at step 325, the NW may configure the cluster head to report “common” CSI for all of the JpUEs and get the “common” CSI from the cluster head CH p.

[0124] At step 330, in cluster zero (C.2), the NW may get the “non-common” CSI from all of the JoUEs. That is, the UEs in cluster zero sharing no common CSI with the cluster head(s) may report their CSI individually to the NW.

[0125] Also, it is possible that some of the UEs in cluster zero (C.2) might share at least partially some common parts with the cluster head(s), e.g., have similar CQI levels or RI or TDCP values, but having different PMIs. Therefore, they may be informed in a reconfiguration message by the NW to not report those common parts of CSI in order to reduce the overhead. This may require at NW level to keep a linkage between UEs with common, non-common and partially common CSIs with respective cluster identifiers (IDs). In this case, if a partial commonality is allowed for the UEs in each cluster, a cluster for UEs with fully non-common CSI (i.e., C.2) may be avoided and all clusters allow the partial commonality.

[0126] At step 340, the NW may check whether a reconfiguration of clusters is triggered. For example, the NW may check whether the time instance t-nT or whether an activation signal is received. If so, the NW may start to determine a new configuration of clusters. The process 300 may return to the step 310. If not, the NW may wait until a next periodic or triggered activation.

[0127] With the process 300, the NW may only inform the UEs in the cell about their role in the cluster, i.e. cluster head / cluster member with a respective configuration for the role, the cluster type, i.e. cluster for UEs with non-common CSI or cluster with common CSI characteristics and the respective cluster ID. From that information, the UEs can understand whether to transmit a full CSI report or partial CSI report, or not to report to the NW. In some examples, the cluster type and / or cluster ID may further indicate a specific CSI parameter to be reported or not reported. In this case, the UEs can further understand what CSI parameter to be reported or not to be reported.

[0128] It will be appreciated that the process 300 is provided only as an example without suggesting any limitation. The clustering / grouping of UEs based on the CSI commonality may be implemented in any suitable way. For example, in some cases, UEs may be split into a fully common cluster containing UEs sharing the fully common CSI and a cluster containing all other UEs. In some other cases, the UEs may be split into a partially common cluster containing UE sharing at least one common CSI parameter with a further UE and a cluster containing all other UEs. Moreover, the clustering may be based on one or more (specific) CSI parameters or the entire CSI. As an example, if two UEs share at least X common CSI parameters, the two UEs may be clustered into a partially common cluster. As another example, if two UEs share a common PMI, the two UEs may be clustered into a partially common cluster associated with the PMI.

[0129] As discussed with reference to FIG. 2 and FIG. 3, embodiments of the present disclosure provide enhancements to CSI feedback by grouping two or more UEs based on their channel characteristics to limit the CSI feedback overhead. It is recognized in the present disclosure that, two or more UEs having common channel characteristics can be configured to report their CSI feedback jointly by means of different CSI configurations and coordination through a BS driven approach. At the same time, the non-common CSI can still be reported by classifying UEs as requiring special UE individual CSI reporting and / or reporting the partial CSI based on the reference CSI or the specifically indicated CSI parameter set by the NW.

[0130] FIG. 4A, 4B and 4C illustrate examples of a CSI commonality in accordance with some example embodiments of the present disclosure. The CSI commonality between UEs may be identified in various ways depending on the characteristics of CSI parameters.

[0131] As an example, as illustrated in FIG. 4A, UEs inside a vehicle are very close toeach other. In this situation, all UEs are moving at the same speed so probably the TDCP reported values at least regarding the first-time correlation lag would be very similar. Similarly, the RSRP values would be close to each other, which leads that at least certain commonality on the CQI values would exist, at least for a wideband CQI value. Finally, PMI would share at least similar W1 wideband beam properties that might be common.

[0132] As another example, in a line-of-sight (LoS) scenario where UEs close to each other, both long-term and short-term channel conditions may be the same between UEs in a group. Therefore, mostly common CSI feedback may be observed. As illustrated in FIG. 4B, UEs packed in a low mobility cluster might experience similar LoS and / or Multipath transmission characteristics. In this case, a commonality of the different CSI reports may be present. Detecting such a correlation of the different CSIs may require some comparison to determine to which extent the commonality of the different CSI reports is and then to determine whether the group CSI reporting is available, e.g., whether a consolidated CSI can be generated.

[0133] If it is determined that the CSI reports can be consolidated, for instance, as the reports have some commonality, as illustrated in FIG. 4C, the commonly selected IV 1 and / or Wf codebook selections may be considered as common and can be reused. However, the IV 2 coefficients may need to be determined and reported separately. In some examples, the IV2. 1 coefficients from UE 1 may be taken as a reference and then, the UE 2 may report IV2. 2 based on a differential CSI quantization with respect to the CSI from UE 1.

[0134] In some examples, for UEs in a non-line-of-sight (nLoS) scenario with many scattering paths, the wideband channel information may be common between the UEs as it captures the long-term frequency-independent characteristics of the propagation channel. However, the sub-band channel information may vary between the UEs as the short-term frequency-dependent characteristics may be different due to the multipath propagation channel. In this case, the commonality shared between the UEs may contain the wideband part of the CSI feedback, while the sub-band part of the CSI feedback may be reported by the individual UEs. This could be exemplified based on FIG. 4C in which the W1 for wideband is common, and W2 is different for UE 1 and UE 2.

[0135] It will be appreciated that the commonality between CSI feedback may be determined in any suitable way, for example, based on historic CSIs, instantaneous CSIs,channel characteristics, spatial locations, mobility and so on. The scope of the present disclosure is not limited in this regard.

[0136] FIG. 5 illustrates a signaling flow of an example process 500 for group CSI reporting in accordance with some example embodiments of the present disclosure. As illustrated in FIG. 5, the process 500 involves a NW device 510, a UE1 520 and a UE2 522. The NW device 510 may be an example of the network apparatus 110 in FIG. 1. The UE1 520 may be an example of the terminal apparatus 120-1 in FIG. 1. The UE2 522 may be an example of the terminal apparatus 120-2 in FIG. 1. The process 500 may be a detailed example of the process 200 in FIG. 2.

[0137] In the process 500, at Step 1, the NW device 510 requests the UE1 520 and the UE2 522 for their UE capabilities. Then the NW device 510 obtains UE capabilities for UE grouping / clustering for partial CSI reporting, e.g., the confirmation from the UEs in the network that the CSI grouping for partial CSI reporting (with common / non-common CSI differentiation) and clustering is supported in the UE capability.

[0138] At Step 2, the NW device 510 transmits a given CSI codebook configuration to the UEs in the network and a CSI-RS to the UEs in order to receive a first CSI report.

[0139] At Step 3, the NW device 510 receives CSI report(s) from the UE1 520 and UE2 522. Based on the received CSI reports received by all the UEs, the NW device 510 determines the CSI commonality across the different UEs in the network.

[0140] In some examples, the received CSI (e.g., PMI / CQI) of UE2 522 may be compared to the received CSI of UE1 520 at the NW device 510. If a match is found (for example, with a certain accuracy threshold), the NW device 510 may determine the CSI reported by the UE1 520 or UE2 522 as a common CSI part. The common CSI part may be used later, for example, to be included in the reference CSI.

[0141] In some examples, the received CSI of UE2 522 may be subtracted from the received CSI of UE1 520. The NW device 510 may determine UEl's CSI feedback as a common CSI part, and determine the difference in CSI feedback between the UE1 520 and UE2 522 as a non-common CSI part. In another example, the non-common CSI part may be used later, for example, to determine the specifically indicated CSI parameter to be reported.

[0142] In some examples, in a case where each UE reports a difference between the CSIprediction and the estimation of a channel at the UE, if the NW device 510 determines that the differences of the two UEs are the same, the NW device 510 may determine the difference as a common CSI part. In this case, one of the UEs may later report such a difference to NW device 510 as the common CSI part, and each UE still sends its own CSI estimation without the prediction (i.e., non-common CSI). This example is particularly applicable when UEs are equipped with a channel predictor.

[0143] Based on the reported CSIs, the NW device 510 determines clusters / groups of the UEs and determines one or more cluster heads. The NW device 510 further determines a reference CSI for one or more clusters. For example, a reference CSI may be determined per cluster.

[0144] At Step 4, the NW device 510 determines information messages for the CSI report configuration and transmits the information messages to the UE1 520 and UE2522. For example, the determined clusters / groups and the cluster head for CSI grouping along with the required CSI reconfigurations and the reference CSI are fed back to the UEs.

[0145] In some embodiments, the NW device 510 may determine and configure how the non-common CSI part is going to be reported. For example, the NW device 510 may determine whether to use a reference CSI or a specifically indicated CSI parameter to indicate the UEs for partial CSI reporting. The NW device 510 may further determine whether reporting of full or partial of the non-common CSI part is needed.

[0146] As illustrated in FIG. 5, the NW device 510 transmits CSI reconfiguration messages to the UE1 520 and UE2 522. The specific CSI reconfiguration messages and assignation of cluster roles, i.e., cluster head or cluster member (secondary UEs) in the cluster, are notified to the different UEs in the network. In the example of FIG. 5, the UE1 520 receives the cluster head assignation and a corresponding CSI configuration. The UE2 522 receives the secondary UE assignation (cluster member) and a corresponding CSI configuration. The CSI configuration in FIG. 5 may be an interchangeable term for the CSI report configuration as described above in FIG. 2.

[0147] For secondary UEs (e.g., UE2 522) in a cluster, the reference CSI is provided. Note that in alternative cases (not shown) an actual reference CSI may not be given, but an indication of a specified part(s) of the CSI to be reported (or not) is given. That is, the reconfiguration of the hard mode or soft mode may be given.

[0148] At Step 5, the NW device 510 transmits a CSI-RS to the UE1 520 and UE2 522 and each of the UEs reports the CSI depending on their roles. As the cluster head, the UE1 520 transmits a full CSI report, i.e., reports full CSI information. As the secondary UE, the UE2 522 transmits its CSI report based on the reference CSI and the corresponding secondary UE configuration provided by the NW device 510. This includes but not limited to, reporting the CSI with respect to the given CSI reference, adding additional non-common CSI information outside the reference CSI, using an absolute or differential CSI representation format, or also acknowledging with one or more Boolean flags the parts of the CSI which are highly correlated to the reference CSI (e.g. CQI, RI, TDCP), thus avoiding a full CSI report. Further details of CSI reporting based on the reference CSI will be described with reference to FIG. 6 in the following.

[0149] At Step 6, the NW device 510 may trigger the reconfiguration of these clusters based on a timer or any other type of network event. In this re-exploration phase, all UEs may report full CSI reports again for the NW device 510 to carry out comparisons again (as in Step 3).

[0150] With the process 500, the role for CSI reporting is indicated to the UE, such that the UE may transmit the full CSI report or the partial CSI report based on the reference CSI to the NW, thereby reducing the CSI feedback signaling overhead.

[0151] FIG. 6 illustrates a signaling flow of an example process 600 for CSI reporting based on a reference CSI (i.e., a soft mode) in accordance with some example embodiments of the present disclosure. In the soft mode, the reference CSI is required for the UEs (e.g., secondary UE) to report the CSI with respect to the reference CSI by e.g., using a differential or absolute representation format. Thus, partial CSI updates can be achieved based on the reference CSI.

[0152] Although the reference CSI is mostly discussed above with reference to the group CSI reporting, it will be appreciated that the reference CSI may be used in any other suitable CSI reporting scenario. For example, a cluster head may report its full CSI report based on a standardized reference CSI reporting mode. In some other examples, the reference CSI may be used in a scenario where, for instance, the reference CSI is not obtained from the cluster head but a different source. Other possible scenario is a case with no group clustering with several UE groups formed by two or more UEs is performed. For instance, we may have have all UEs in the BS coverage may have at least a commonCSI parameter which would be equivalent to create only a “single cluster”. Also the reference CSI may be UE specific and one or more terminal apparatuses receive this reference CSI separately, which contrasts to another case in which the reference CSI is common across secondary UEs in the same cluster group. For the purpose of discussion, the process 600 will be described with the network apparatus 110 and the terminal apparatus 120 in FIG. 1.

[0153] As illustrated in FIG. 6, in the process 600, the network apparatus 110 transmits 610 to the terminal apparatus 120, a CSI report configuration indicating a reference CSI. The network apparatus 110 may use any suitable message with a low bit overhead to transmit the CSI report configuration in DE to provide this reference CSI to UEs. The terminal apparatus 120 receives the CSI report configuration.

[0154] As discussed with reference to FIG. 2, the reference CSI may comprise a reference CSI parameter, information to be reported in association with a CSI parameter, a part of a CSI parameter, and / or a full CSI report. The reference CSI may be determined based on a historic CSI, an instantaneous CSI, a predefined CSI, or a CSI commonality level between the terminal apparatus 120 and one or more further terminal apparatuses. For example, a common CSI parameter between various UEs may be included in the reference CSI. It will be appreciated that the reference CSI is not limited to information obtained from the head UE in the cluster, but may be related to other type of information, for example, historical CSI statistics collected by the NW in the past.

[0155] Based on the CSI report configuration, the terminal apparatus 120 determines 614 a representation format of a CSI report. The representation format indicates at least one CSI parameter to be reported and at least one format corresponding to the at least one parameter to be reported. The at least one format may comprise one of: a differential value, an absolute value, an absolute coefficient, a differential coefficient, or a flag. For example, the terminal apparatus 120 may determine to generate the CSI report in a differential format with respect to the reference CSI or in an absolute format based on the reference CSI.

[0156] In some embodiments, the terminal apparatus 120 may determine the representation format of the CSI report based on the reference CSI. As an example, if determining that the reference CSI is a full CSI report, the terminal apparatus 120 may determine that the representation format of the CSI report is a differential CSI report withrespect to the full CSI report; and determine the CSI parameter(s) to be reported and the corresponding format(s) based on CSI parameters and formats of the CSI parameters in the full CSI report. As another example, if a reference value of a CSI parameter is indicated in the reference CSI, the terminal apparatus 120 may determine to report the CSI parameter in a differential value or with a flag to indicate that its own CSI value is the same or similar to the reference value.

[0157] Alternatively or additionally, the terminal apparatus 120 may determine the representation format of the CSI report based on information other than the reference CSI indicated in the CSI report configuration. For example, a field in the CSI report configuration may be used to indicate the representation format of the CSI report.

[0158] Based on the determined representation format and a channel measurement, the terminal apparatus 120 generates 616 the CSI report. The terminal apparatus 120 then transmits 618 the CSI report to the network apparatus 110. The network apparatus 110 receives 620 the CSI report.

[0159] In some embodiments, the reference CSI may comprise a reference CSI parameter, the terminal apparatus 120 may determine, based on the channel measurement, a differential value with respect to the reference CSI parameter and generate the CSI report based on the differential value.

[0160] As an example, the reference CSI may include a reference TDCP value or a wideband CQI provided by the NW. In this case, the terminal apparatus 120 may report its TDCP value or sub-band CQI differentially with respect to the reference TDCP value or wideband CQI provided by the NW.

[0161] In some embodiments, the reference CSI may comprise information to be reported in association with a CSI parameter, for example, a set of beams, a set of subbands, and / or a set of delay taps, the terminal apparatus 120 may determine, based on the channel measurement and the information, a differential or absolute set of one or more coefficients of the CSI parameter associated with the information; and generate the CSI report based on the differential or absolute coefficient of the CSI parameter.

[0162] As an example, the reference CSI may include indexes of a set of beams and delay taps reported by the cluster head. In this case, the terminal apparatus 120, as a secondary UE, may report its coefficients referred to the cluster head codebook choices(i.e., the beam and / or delay indexes). As another example, if the reference CSI includes both the indexes of the set of beams and coefficients of the set of beams, the terminal apparatus 120 may report its coefficients in the differential format.

[0163] In some examples, depending on the difference with respect to the reference CSI, the terminal apparatus 120, e.g., as a secondary UE, may decide to report or not report some parts like CQI or TDCP (if they are very close) by just reporting a flag to report that its own measurement is similar to the reference CSI (e.g., from the cluster head). For example, if values of the CSI parameter from various UEs are similar with respect to a threshold or a similarity condition, the flag may be set with a value ‘1 ’, or vice versa. In some examples, if beams in the reference CSI are reported like in Type I CSI (with a fixed amplitude), the terminal apparatus 120 may also send this flag and only provide the cophasing coefficient associated with the beam or beams reported by the cluster head. Notice that in the case that a flag value is ‘O’, the terminal apparatus might send in a second part of the CSI report, the absolute value associated with the CSI parameter. The flags indication with ‘0’ can also be used as statistical indication for the NW to reconfigure the clustering and re-determine the associated reference CSI per cluster.

[0164] Note that in some cases the differential reporting might be more adequate but in some other cases absolute coefficients reporting with respect to the reference CSI may be a better choice. For instance, if the reference CSI comprises information of the cluster head UE regarding selected beam indexes, delay tap indexes or even a set of sub-bands accompanied (or not) by a set of space-frequency coefficients, the secondary UE may be enabled to send the non-common CSI, e.g., in an absolute coefficient representation format if no reference coefficients are given. Moreover, the secondary UE may send the non-common CSI in an absolute coefficient representation format if additional beam indexes, delay tap indexes or sub-bands need to be reported as part of the non-common CSI information. Otherwise, when reference coefficients are present, the differential coefficient representation may be used.

[0165] With the process 600, the reference CSI can be used for the UEs to report differentially with respect to the reference CSI (e.g., in a differential value) or report a part of the CSI with respect to the reference CSI (e.g., only coefficients associated with a set of beams), such that the CSI feedback signaling overhead can be reduced.

[0166] Although transmitting the reference CSI (especially the full CSI report) maycause some overhead, a trade-off of bit overhead in downlink direction can be beneficial for the overall CSI feedback signaling. For instance, the NW may afford to send the complete CSI report from the cluster head toward the secondary UEs, thus enabling the secondary UEs in the cluster to send a fully differential CSI report with respect to this CSI reference, thereby reducing the CSI feedback signaling overhead of the secondary UEs.

[0167] FIG. 7 illustrates a signaling flow of an example process 700 for CSI reporting based on a specifically indicated CSI parameter (i.e., a hard mode) in accordance with some example embodiments of the present disclosure. In the hard mode, the UE (e.g., a secondary UE) may only provide updates of one or more specifically indicated CSI parameters.

[0168] Similarly, although the hard mode is mostly discussed above with reference to the group CSI reporting, it will be appreciated that the hard mode may be used in any other suitable CSI reporting scenario. For example, the specifically indicated CSI parameter to be reported and / or to be not reported may be used in a scenario where no group clustering with several UE groups formed by two or more UEs is performed. For instance, all UEs in the BS coverage may have at least a common CSI parameter to be reported and / or not reported, which is equivalent to creating a single cluster. Another possibility is that one or more UEs may have a separate and fully specific CSI report configuration comprising the CSI parameters to be reported and / or not reported, which contrast to the case in which secondary UEs in the same cluster may share the same CSI reporting configuration. For the purpose of discussion, the process 700 will be described with the network apparatus 110 and the terminal apparatus 120 in FIG. 1.

[0169] As illustrated in FIG. 7, in the process 700, the network apparatus 110 transmits 710, to the terminal apparatus 120, a CSI report configuration indicating a CSI parameter to be reported and / or a CSI parameter to be not reported, i.e., at least one specifically CSI parameter to be reported or not. The terminal apparatus 120 receives 712 the CSI report configuration.

[0170] This configuration mode is also referred to as “hard mode” because it works like ON / OFF. This configuration specifically indicates what to report and / or what not to report. The restriction of what to report and / or what not to report may be fixed or predefined in the CSI report configuration.

[0171] In an exemplary implementation, the network apparatus 110 may configure the terminal apparatus 120 (e.g., as a secondary UE) to perform partial updates of certain CSI quantities (PMI, CQI, RI, TDCP, and / or RSRP) and not reporting others. The specifically indicated parameter may be obtained based on the CSI commonality between the various UEs in the clustering group. For example, a common CSI parameter may be specifically indicated as to be not reported.

[0172] It will be appreciated that the specifically indicated CSI parameter may be determined in any suitable way. For example, the NW may specify one or more specific CSI parameters to be reported for a specific UE. The scope of the present disclosure is not limited in this regard.

[0173] In some embodiments, the specifically indicated CSI parameter may be a part of a CSI parameter and / or information to be reported in association with a CSI parameter. For example, the CSI parameter PMI may be split into beams, delay taps and spacefrequency coefficients, and a set of beams indexes, a set of delay indexes, and / or spacefrequency coefficients constrained to a given set space-frequency components / indexes, etc., which may be specifically indicated to be reported or to be not reported.

[0174] Based on the CSI report configuration, the terminal apparatus 120 determines 714 a first CSI parameter to be reported and a second CSI parameter to be not reported. As an example, the CSI parameter indicated to be not reported may be removed from a default list of CSI parameters to be reported and the remaining CSI parameters may be considered as the CSI parameters to be reported. As another example, only the CSI parameter(s) indicated to be reported is considered to be reported to the network apparatus 110 and other CSI parameters may be considered unnecessary to be reported.

[0175] The terminal apparatus 120 further determines 716 whether the second CSI parameter to be not reported is associated with a determination of the first CSI parameter to be reported. For example, the terminal apparatus 120 may check whether the second CSI parameter needs to be determined / calculated first such that the first CSI parameter can be determined / calculated.

[0176] In accordance with a determination 718 that the second CSI parameter is associated with the determination of the first CSI parameter, the terminal apparatus 120 may determine 720 the first CSI parameter based on a channel measurement by determining the second CSI parameter. In other words, if the parameter to be not reportedis associated with the determination of the first CSI parameter, the terminal apparatus 120 may determine the second CSI parameter first and then determine the first CSI parameter, although the second CSI parameter is not to be reported.

[0177] In some embodiments, the terminal apparatus 120 may determine the second CSI parameter by using a complexity-reduced calculation method associated with a CSI calculation capability of the terminal apparatus. In this way, calculation resources for the second CSI parameter can be saved. For example, PMI calculation complexity may be lowered for instance by using a simpler or customized numerical method for Discrete Fourier Transform (DFT) or using a low complexity Single or Eigenvalue Decomposition (SVD / EVD).

[0178] Alternatively, in accordance with a determination 718 that the second CSI parameter is associated with the determination of the first CSI parameter, the terminal apparatus 120 may determine 722 the first CSI parameter based on the CSI calculation capability of the terminal apparatus 120 and a channel measurement without determining the second CSI parameter. In other words, if the parameter to be not reported is associated with the determination of the first CSI parameter, the terminal apparatus 120 may determine, based on its capability, the first CSI parameter without determining the second CSI parameter first. As an example, the terminal apparatus 120 may be enabled with a specific computation method to calculate the first CSI parameter. As another example, a predefined value of the second CSI parameter may be used as a reference for the actual value, such that the terminal apparatus 120 may determine the first CSI parameter based on the reference value.

[0179] In some embodiments, the terminal apparatus 120 may transmit its CSI calculation capability to the network apparatus 110. The network apparatus 110 may determine the specifically indicated CSI parameter for the terminal apparatus 120 based on the CSI calculation capability and provide a customized CSI configuration accordingly to the capability. It may be discretionary for the network apparatus 110 to request the terminal apparatus 120 to use this low resource computation feature, as the network apparatus 110 may prefer high accuracy CSI computations.

[0180] In some embodiments, if determining that the CSI calculation capability indicates that the terminal apparatus 120 is capable of determining the first CSI parameter without determining the second CSI parameter, the network apparatus 110 may determine that theCSI report configuration for the terminal apparatus 120 indicates that there is no need to report the second CSI parameter.

[0181] In some embodiments, if determining that the CSI calculation capability indicates that the terminal apparatus 120 is capable of determining the first CSI parameter by determining the second CSI parameter using a complexity-reduced calculation method, the network apparatus 110 may determine that the CSI report configuration for the terminal apparatus 120 indicates that there is no need to report the second CSI parameter.

[0182] If the feature is enabled, the terminal apparatus 120 during the CSI computation may determine if a certain computation is possible to derive the first CSI parameter without calculating the second CSI parameter or whether there is an alternative possibility to run a low complexity algorithm to calculate the second CSI parameter so as to determine the first CSI parameter to be reported. For instance, the CQI and RI may both depend on the PMI calculation, if the PMI is indicated to be not reported, the PMI may be calculated using a complexity-reduced calculation method and then the CQI and RI may be determined based on the calculated PMI and reported to the network apparatus 110.

[0183] The terminal apparatus 120 further transmits 724, to the network apparatus 110, a CSI report including the first CSI parameter and not including the second CSI parameter. The network apparatus 110 receives the CSI report from the terminal apparatus 120.

[0184] In other cases, the terminal apparatus 120 may not have the possibility to flexibly tune the calculation algorithms, e.g., the UE does not have the low resource computation capability. In such case, the terminal apparatus 120 may prevent from performing a certain operation if it cannot proceed because, for example, the accuracy might be not good enough or the resources are insufficient for using the low resource computation. The terminal apparatus 120 may inform the NW in the CSI report about the impossibility to perform such a complexity-reduced or relaxed calculation method.

[0185] With the process 700, the UEs can be indicated specifically of what to report and / or what to not report. The UEs can further determine the CSI parameter to be reported in an efficient way, for example, using a complexity-reduced calculation method to determine the associated CSI parameter to be not reported.

[0186] Several example embodiments for CSI enhancements have been described withrespect to FIG. 2 to FIG. 7. It is to be understood that the processes 200, 300, 500, 600 and 700 described above may be applied separately or in combinations in any suitable way. For example, the reference CSI and / or the specifically indicated CSI parameter to be reported or to be not reported may be applied in the group CSI reporting scenario, such that the secondary UEs can report the partial CSI report based on the reference CSI and / or the specifically indicated CSI parameter. In some other examples, the reference CSI and / or the specifically indicated CSI parameter may be applied in other CSI reporting scenarios. The scope of the present disclosure is not limited here.

[0187] In summary, embodiments of the present disclosure are related to CSI feedback enhancements, and provide solutions for the scenario where multiple UEs are reporting similar CSI parameters to the NW. For example, considering that the small distance between UEs may yield spatially consistent channel characteristics (large-channel scale channel characteristics and in certain cases also small-scale channel characteristics), the proposed solutions of CSI enhancements can be applied, e.g., for MIMO-CSI feedback.

[0188] In some embodiments, the proposed solutions can reduce the CSI feedback overhead when two or more UEs share spatially consistent channel characteristics, for example, by clustering / grouping UEs that fully or partially share a common CSI feedback part (e.g., RI, PMI, CQI or TDCP). The proposed solutions further provide a way to split the CSI feedback into a common part for the UE cluster / group and a UE-specific CSI feedback part that is reported with dedicated CSI feedback. Moreover, the proposed solutions provide a mechanism to select a UE as a group “head” responsible for reporting the common part of the CSI feedback.

[0189] In some examples, the NW may compare the CSI of each UE and combine the UEs into a plurality of clusters that have similar CSI reporting quantities. Within the cluster, the NW may select the head UE that reports some representative CSI of the whole group (i.e. common CSI). The head UE may report the common CSI representing the group for a given time window. This common CSI may be the full CSI report of the head UE. At the same time, other secondary UEs within the cluster may report non-common CSI parts which may be expressed with respect to reference CSI values, which might be related to the cluster head UE CSI or other predefined values. In some examples, a special cluster for UEs with fully non-common CSI to other clusters may also be created and these UEs must transmit the full CSI individually.

[0190] A more general case in which partial commonality of CSI values per cluster may be enabled. In some examples, secondary UEs belonging to a certain cluster may transmit the non-common part of the CSI fully individually, whereas the part defined as common is transmitted by cluster head UE. In other words, all UEs in the cluster, secondary UE and cluster head UE transmit either a partial CSI update or full CSI respectively with a reasonable bit overhead reduction and UE computational resource utilization.

[0191] This contrasts with the currently used solutions in which the head UE has a significant computational / energy consumption burden to aggregate the CSI of the cluster (with sidelink communication to neighbor UEs) and takes the full responsibility of transmitting the consolidated cluster CSI to the NW. This type of scheme may carry a number of issues related to the UE functionality including computing capabilities and energy consumption.Example Method

[0192] FIG. 8 shows a flowchart of an example method 800 implemented at a terminal apparatus in accordance with some example embodiments of the present disclosure. For the purpose of discussion, the method 800 will be described from the perspective of the terminal apparatus 120 in FIG. 1.

[0193] At block 810, the terminal apparatus 120 receives, from a network apparatus, a channel state information (CSI) report configuration indicating a role for CSI reporting.

[0194] At block 820, in accordance with a determination that the role is a cluster head for group CSI reporting, the terminal apparatus 120 transmits a full CSI report to the network apparatus based on the CSI report configuration.

[0195] At block 830, in accordance with a determination that the role is a cluster member for group CSI reporting, the terminal apparatus 120 transmits a partial CSI report or refrain from transmitting a CSI report to the network apparatus based on the CSI report configuration.

[0196] In some example embodiments, the terminal apparatus 120 is further caused to: determine the partial CSI report by refraining from including a common CSI parameter between the terminal apparatus and a further terminal apparatus in a same cluster.

[0197] In some example embodiments, the common CSI parameter between the terminal apparatus and the further terminal apparatus is associated with a same CSI parameter value or different CSI parameter values satisfying a commonality condition.

[0198] In some example embodiments, the terminal apparatus 120 is further caused to: receive a reference CSI from the network apparatus; and in accordance with the determination that the role is the cluster member for group CSI reporting, determine the partial CSI report based on the reference CSI.

[0199] In some example embodiments, the reference CSI comprises at least one of: a reference CSI parameter, information to be reported in association with a CSI parameter, a part of a CSI parameter, or a full CSI report.

[0200] In some example embodiments, the information to be reported in association with the CSI parameter comprises an indication of at least one of: a set of beams, a set of subbands, or a set of delay taps.

[0201] In some example embodiments, the terminal apparatus 120 is further caused to: receive, from the network apparatus, at least one of a CSI parameter to be reported or a CSI parameter to be not reported; and in accordance with the determination that the role is the cluster member for group CSI reporting, determine the partial CSI report based on the at least one of the CSI parameter to be reported or the CSI parameter to be not reported.

[0202] In some example embodiments, the terminal apparatus 120 is further caused to: receive, from the network apparatus, a cluster indication of a cluster which the terminal apparatus belongs to, and the cluster indication indicates at least one of a cluster type or a cluster identifier.

[0203] In some example embodiments, the cluster indication indicates that the cluster which the terminal apparatus belongs to is a fully common cluster, a partially common cluster, or a fully non-common cluster.

[0204] In some example embodiments, the terminal apparatus 120 is further caused to: in accordance with a determination that the cluster is the fully common cluster and the role is the cluster member for group CSI reporting, determine to refrain from transmitting a CSI report to the network apparatus; in accordance with a determination that the cluster is the partially common cluster and the role is the cluster member for group CSI reporting, determine to transmit the partial CSI report to the network apparatus; and in accordancewith a determination that the cluster is the fully non-common cluster and the role is for non-common CSI reporting, determine to transmit a full CSI report to the network apparatus.

[0205] In some example embodiments, the cluster head and the cluster member are associated with a same cluster or different clusters.

[0206] In some example embodiments, the cluster head is a first cluster head associated with a first cluster, and the terminal apparatus is further caused to: receive a role change indication of: a change of the role from the first cluster head to a first cluster member, the first cluster member being associated with the first cluster or a further cluster different from the first cluster, or a change of the role from the first cluster head to a second cluster head associated with a second cluster different from the first cluster.

[0207] In some example embodiments, the cluster member is a first cluster member associated with a first cluster and the terminal apparatus is further caused to: receive a role change indicating one of: a change of the role from the first cluster member to a second cluster member associated with a second cluster different from the first cluster, or a change of the role from the first cluster member to a cluster head associated with the first cluster or a second cluster different from the first cluster.

[0208] In some example embodiments, the full CSI report or the partial CSI report comprises at least a part of one of: a precoding matrix indicator (PMI), a channel quality indicator (CQI), a rank indicator (RI), time domain channel proprieties (TDCP), or a reference signal received power (RSRP).

[0209] FIG. 9 shows a flowchart of an example method 900 implemented at a network apparatus in accordance with some example embodiments of the present disclosure. For the purpose of discussion, the method 900 will be described from the perspective of the network apparatus 110 in FIG. 1.

[0210] At block 910, the network apparatus 110 determines a CSI commonality level between a terminal apparatus and one or more further terminal apparatuses.

[0211] At block 920, the network apparatus 110 determines, for the terminal apparatus, a role for CSI reporting based on the CSI commonality level.

[0212] At block 930, the network apparatus 110 transmits, to the terminal apparatus, a CSI report configuration indicating the role for CSI reporting.

[0213] In some example embodiments, determining the CSI commonality level between the terminal apparatus and the one or more further terminal apparatuses comprises: in accordance with a determination that a common CSI parameter is present between the terminal apparatus and the one or more further terminal apparatuses, determining that the terminal apparatus and the one or more further terminal apparatuses share an at least partially common CSI; and in accordance with a determination that no common CSI parameter is present between the terminal apparatus and the one or more further terminal apparatuses, determining that the terminal apparatus and the one or more further terminal apparatuses share no common CSI.

[0214] In some example embodiments, the common CSI parameter between the terminal apparatus and the one or more terminal apparatus is associated with a same CSI parameter value or different CSI parameter values satisfying a commonality condition.

[0215] In some example embodiments, determining, for the terminal apparatus, the role for CSI reporting based on the CSI commonality level comprises: in accordance with a determination that the terminal apparatus and the one or more further terminal apparatuses share the at least partially common CSI, determining that the role for the terminal apparatus is one of: a cluster head for group CSI reporting configured to transmit a full CSI report, a cluster member for group CSI reporting configured to transmit a partial CSI report, or a cluster member for group CSI reporting configured to refrain from transmitting a CSI report.

[0216] In some example embodiments, determining the role for the terminal apparatus comprises determining whether the terminal apparatus is the cluster head or the cluster member based on at least one of: RSRP values of the terminal apparatus and the one or more further terminal apparatuses, distances between the terminal apparatus and the one or more further terminal apparatuses, distances between the terminal apparatus and the network apparatus, a rotation rule for a cluster or a predefined characteristic or capability of the terminal apparatus and the one or more further terminal apparatuses.

[0217] In some example embodiments, determining, for the terminal apparatus, the role for CSI reporting based on the CSI commonality level comprises: in accordance with a determination that the terminal apparatus and the one or more further terminal apparatuses share no common CSI, determining that the role for the terminal apparatus is a role for non-common CSI reporting configured to transmit a full CSI report.

[0218] In some example embodiments, determining the CSI commonality level between the terminal apparatus and the one or more further terminal apparatuses comprises determining the CSI commonality level based on at least one of: historical CSIs reported from the terminal apparatus and the one or more further terminal apparatuses, instantaneous CSIs reported from the terminal apparatus and the one or more further terminal apparatuses, channel characteristics of the terminal apparatus and the one or more further terminal apparatuses, locations of the terminal apparatus and the one or more further terminal apparatuses, or mobility of the terminal apparatus and the one or more further terminal apparatuses.

[0219] In some example embodiments, the network apparatus 110 is further caused to transmit to the terminal apparatus an indication of a change of the role for CSI reporting.

[0220] In some example embodiments, the network apparatus 110 is further caused to: transmitting to the terminal apparatus, a cluster indication of a cluster which the terminal apparatus belongs to, and the cluster indication indicates at least one of a cluster type or a cluster identifier.

[0221] In some example embodiments, the cluster indication indicates that the cluster which the terminal apparatus belongs to is one of a fully common cluster, a partially common cluster, or a fully non-common cluster.

[0222] In some example embodiments, the network apparatus 110 is further caused to transmit, to the terminal apparatus, at least one of: a reference CSI, or at least one of a CSI parameter to be reported or a CSI parameter to be not reported.

[0223] In some example embodiments, a terminal apparatus capable of performing any of the method 800 (for example, the terminal apparatus 120 in FIG. 1) may comprise means for performing the respective operations of the method 800. The means may be implemented in any suitable form. For example, the means may be implemented in a circuitry or software module. The terminal apparatus may be implemented as or included in the terminal apparatus 120 in FIG. 1.

[0224] In some example embodiments, the terminal apparatus 120 comprises means for receiving, from a network apparatus, a channel state information (CSI) report configuration indicating a role for CSI reporting; means for in accordance with a determination that the role is a cluster head for group CSI reporting, transmitting a fullCSI report to the network apparatus based on the CSI report configuration; and means for in accordance with a determination that the role is a cluster member for group CSI reporting, transmitting a partial CSI report or refrain from transmitting a CSI report to the network apparatus based on the CSI report configuration.

[0225] In some example embodiments, the terminal apparatus 120 may further comprise: means for determining the partial CSI report by refraining from including a common CSI parameter between the terminal apparatus and a further terminal apparatus in a same cluster.

[0226] In some example embodiments, the common CSI parameter between the terminal apparatus and the further terminal apparatus is associated with a same CSI parameter value or different CSI parameter values satisfying a commonality condition.

[0227] In some example embodiments, the terminal apparatus 120 may further comprise: means for receiving a reference CSI from the network apparatus; and means for in accordance with the determination that the role is the cluster member for group CSI reporting, determining the partial CSI report based on the reference CSI.

[0228] In some example embodiments, the reference CSI comprises at least one of: a reference CSI parameter, information to be reported in association with a CSI parameter, a part of a CSI parameter, or a full CSI report.

[0229] In some example embodiments, the information to be reported in association with the CSI parameter comprises an indication of at least one of: a set of beams, a set of subbands, or a set of delay taps.

[0230] In some example embodiments, the terminal apparatus is further caused to: means for receiving, from the network apparatus, at least one of a CSI parameter to be reported or a CSI parameter to be not reported; and means for in accordance with the determination that the role is the cluster member for group CSI reporting, determining the partial CSI report based on the at least one of the CSI parameter to be reported or the CSI parameter to be not reported.

[0231] In some example embodiments, the terminal apparatus 120 may further comprise: means for receiving, from the network apparatus, a cluster indication of a cluster which the terminal apparatus belongs to, and the cluster indication indicates at least one of a cluster type or a cluster identifier.

[0232] In some example embodiments, the cluster indication indicates that the cluster which the terminal apparatus belongs to is a fully common cluster, a partially common cluster, or a fully non-common cluster.

[0233] In some example embodiments, the terminal apparatus 120 may further comprise: means for in accordance with a determination that the cluster is the fully common cluster and the role is the cluster member for group CSI reporting, determining to refrain from transmitting a CSI report to the network apparatus; means for in accordance with a determination that the cluster is the partially common cluster and the role is the cluster member for group CSI reporting, determining to transmit the partial CSI report to the network apparatus; and means for in accordance with a determination that the cluster is the fully non-common cluster and the role is for non-common CSI reporting, determining to transmit a full CSI report to the network apparatus.

[0234] In some example embodiments, the cluster head and the cluster member are associated with a same cluster or different clusters.

[0235] In some example embodiments, the cluster head is a first cluster head associated with a first cluster, and the terminal apparatus is further caused to: means for receiving a role change indication of: means for a change of the role from the first cluster head to a first cluster member, the first cluster member being associated with the first cluster or a further cluster different from the first cluster, or means for a change of the role from the first cluster head to a second cluster head associated with a second cluster different from the first cluster.

[0236] In some example embodiments, the cluster member is a first cluster member associated with a first cluster and the terminal apparatus is further caused to: means for receiving a role change indicating one of: means for a change of the role from the first cluster member to a second cluster member associated with a second cluster different from the first cluster, or means for a change of the role from the first cluster member to a cluster head associated with the first cluster or a second cluster different from the first cluster.

[0237] In some example embodiments, the full CSI report or the partial CSI report comprises at least a part of one of: a precoding matrix indicator (PMI), a channel quality indicator (CQI), a rank indicator (RI), time domain channel proprieties (TDCP), or a reference signal received power (RSRP).

[0238] In some example embodiments, a network apparatus capable of performing any of the method 900 (for example, the network apparatus 110 in FIG. 1) may comprise means for performing the respective operations of the method 900. The means may be implemented in any suitable form. For example, the means may be implemented in a circuitry or software module. The network apparatus may be implemented as or included in the network apparatus 110 in FIG. 1.

[0239] In some example embodiments, the network apparatus 110 comprises means for determining a CSI commonality level between a terminal apparatus and one or more further terminal apparatuses; means for determining, for the terminal apparatus, a role for CSI reporting based on the CSI commonality level; and means for transmitting, to the terminal apparatus, a CSI report configuration indicating the role for CSI reporting.

[0240] In some example embodiments, the means for determining the CSI commonality level between the terminal apparatus and the one or more further terminal apparatuses comprises: means for in accordance with a determination that a common CSI parameter is present between the terminal apparatus and the one or more further terminal apparatuses, determining that the terminal apparatus and the one or more further terminal apparatuses share an at least partially common CSI; and in accordance with a determination that no common CSI parameter is present between the terminal apparatus and the one or more further terminal apparatuses, determining that the terminal apparatus and the one or more further terminal apparatuses share no common CSI.

[0241] In some example embodiments, the common CSI parameter between the terminal apparatus and the one or more terminal apparatus is associated with a same CSI parameter value or different CSI parameter values satisfying a commonality condition.

[0242] In some example embodiments, the means for determining, for the terminal apparatus, the role for CSI reporting based on the CSI commonality level comprises: means for in accordance with a determination that the terminal apparatus and the one or more further terminal apparatuses share the at least partially common CSI, determining that the role for the terminal apparatus is one of: a cluster head for group CSI reporting configured to transmit a full CSI report, a cluster member for group CSI reporting configured to transmit a partial CSI report, or a cluster member for group CSI reporting configured to refrain from transmitting a CSI report.

[0243] In some example embodiments, the means for determining the role for theterminal apparatus comprises: means for determining whether the terminal apparatus is the cluster head or the cluster member based on at least one of: RSRP values of the terminal apparatus and the one or more further terminal apparatuses, distances between the terminal apparatus and the one or more further terminal apparatuses, distances between the terminal apparatus and the network apparatus, a rotation rule for a cluster or a predefined characteristic or capability of the terminal apparatus and the one or more further terminal apparatuses.

[0244] In some example embodiments, the means for determining, for the terminal apparatus, the role for CSI reporting based on the CSI commonality level comprises: means for in accordance with a determination that the terminal apparatus and the one or more further terminal apparatuses share no common CSI, determining that the role for the terminal apparatus is a role for non-common CSI reporting configured to transmit a full CSI report.

[0245] In some example embodiments, the means for determining the CSI commonality level between the terminal apparatus and the one or more further terminal apparatuses comprises: means for determining the CSI commonality level based on at least one of: historical CSIs reported from the terminal apparatus and the one or more further terminal apparatuses, instantaneous CSIs reported from the terminal apparatus and the one or more further terminal apparatuses, channel characteristics of the terminal apparatus and the one or more further terminal apparatuses, locations of the terminal apparatus and the one or more further terminal apparatuses, or mobility of the terminal apparatus and the one or more further terminal apparatuses.

[0246] In some example embodiments, the network apparatus 110 may further comprise: means for transmitting to the terminal apparatus an indication of a change of the role for CSI reporting.

[0247] In some example embodiments, the network apparatus 110 may further comprise: means for transmitting to the terminal apparatus, a cluster indication of a cluster which the terminal apparatus belongs to, and the cluster indication indicates at least one of a cluster type or a cluster identifier.

[0248] In some example embodiments, the cluster indication indicates that the cluster which the terminal apparatus belongs to is one of a fully common cluster, a partially common cluster, or a fully non-common cluster.

[0249] In some example embodiments, the network apparatus 110 may further comprise: means for transmitting, to the terminal apparatus, at least one of: a reference CSI, or at least one of a CSI parameter to be reported or a CSI parameter to be not reported.

[0250] FIG. 10 shows a flowchart of an example method 1000 implemented at a terminal apparatus in accordance with some example embodiments of the present disclosure. For the purpose of discussion, the method 1000 will be described from the perspective of the terminal apparatus 120 in FIG. 1.

[0251] At block 1010, the terminal apparatus 120 receives, from a network apparatus, a channel state information (CSI) report configuration indicating at least one of a CSI parameter to be reported or a CSI parameter to be not reported.

[0252] At block 1020, the terminal apparatus 120 determines, based on the CSI report configuration, a first CSI parameter to be reported and a second CSI parameter to be not reported.

[0253] At block 1030, the terminal apparatus 120 determines, whether the second CSI parameter is associated with a determination of the first CSI parameter.

[0254] At block 1040, in accordance with a determination that the second CSI parameter is associated with the determination of the first CSI parameter,

[0255] At block 1050, the terminal apparatus 120 determines the first CSI parameter based on a channel measurement by determining the second CSI parameter, or

[0256] At block 1060, the terminal apparatus 120 determines the first CSI parameter based on a CSI calculation capability of the terminal apparatus and a channel measurement without determining the second CSI parameter.

[0257] At block 1070, the terminal apparatus 120 transmits, to the network apparatus, a CSI report including the first CSI parameter and not including the second CSI parameter.

[0258] In some example embodiments, the terminal apparatus 120 is further caused to transmit the CSI calculation capability to the network apparatus, and the CSI report configuration is received from the network apparatus based on the CSI calculation capability.

[0259] In some example embodiments, determining the first CSI parameter based on the channel measurement by determining the second CSI parameter comprises: determiningthe second CSI parameter by using a complexity-reduced calculation method associated with the CSI calculation capability of the terminal apparatus.

[0260] In some example embodiments, the first CSI parameter or the second CSI parameter comprises at least a part of one of: a precoding matrix indicator (PMI), a channel quality indicator (CQI), a rank indicator (RI), time domain channel properties (TDCP), or a reference signal received power (RSRP).

[0261] In some example embodiments, at least the part of the PMI comprises at least one of: a set of beam indexes, a set of delay tap indexes, or a set of space-frequency coefficients constrained to a set of space-frequency indexes.

[0262] In some example embodiments, the terminal apparatus 120 is further caused to: receiving, from the network apparatus, an indication of a role for CSI reporting.

[0263] In some example embodiments, the terminal apparatus 120 is further caused to: receiving, from the network apparatus, a cluster indication of a cluster which the terminal apparatus belongs to, and the cluster indication indicates at least one of a cluster type or a cluster identifier.

[0264] In some example embodiments, the cluster indication indicates that the cluster which the terminal apparatus belongs to is a fully common cluster, a partially common cluster, or a fully non-common cluster.

[0265] In some example embodiments, the terminal apparatus 120 is further caused to: in accordance with a determination that the cluster is the partially common cluster and the role is a cluster member for group CSI reporting, determining to transmit a partial CSI report to the network apparatus based on the at least one of the CSI parameter to be reported or the CSI parameter to be not reported.

[0266] In some example embodiments, the terminal apparatus 120 is further caused to receive, from the network apparatus, a role change indication of: a change of the role from a first cluster head to a first cluster member, or a change of the role from a first cluster member to a second cluster member or a second cluster head.

[0267] FIG. 11 shows a flowchart of an example method 1100 implemented at a network apparatus in accordance with some example embodiments of the present disclosure. For the purpose of discussion, the method 1100 will be described from the perspective of the network apparatus 110 in FIG. 1.

[0268] At block 1110, the network apparatus 110 determines, for a terminal apparatus, a channel state information (CSI) report configuration based on a CSI commonality level between the terminal apparatus and one or more further terminal apparatuses, the CSI report configuration indicating at least one of a CSI parameter to be reported or a CSI parameter to be not reported.

[0269] At block 1120, the network apparatus 110 transmits the CSI report configuration to the terminal apparatus.

[0270] At block 1130, the network apparatus 110 receives a CSI report from the terminal apparatus.

[0271] In some example embodiments, the network apparatus 110 is further caused to receive a CSI calculation capability from the terminal apparatus, and determining the CSI report configuration based on the CSI commonality level comprises: determining, for the terminal apparatus, a first CSI parameter to be reported and a second CSI parameter to be not reported based on the CSI commonality level; and determining the at least one of the CSI parameter to be reported or the CSI parameter to be not reported based on the CSI calculation capability and the first CSI parameter to be reported and the second CSI parameter to be not reported.

[0272] In some example embodiments, determining the at least one of the CSI parameter to be reported or the CSI parameter to be not reported based on the CSI calculation capability and the first CSI parameter to be reported and the second CSI parameter to be not reported comprises: in accordance with a determination that the CSI calculation capability indicates that the terminal apparatus is capable of determining the first CSI parameter without determining the second CSI parameter, determining that the CSI report configuration indicates there is no need to report the second CSI parameter.

[0273] In some example embodiments, determining the at least one of the CSI parameter to be reported or the CSI parameter to be not reported based on the CSI calculation capability and the first CSI parameter to be reported and the second CSI parameter to be not reported comprises: in accordance with a determination that the second CSI parameter is associated with a determination of the first CSI parameter, and the CSI calculation capability indicates that the terminal apparatus is capable of determining the first CSI parameter by determining the second CSI parameter using a complexity-reduced calculation method, determining that the CSI report configuration indicates there is noneed to report the second CSI parameter.

[0274] In some example embodiments, the at least one of the CSI parameter to be reported or the CSI parameter to be not reported comprises at least a part of one of: a precoding matrix indicator (PMI), a channel quality indicator (CQI), a rank indicator (RI), time domain channel properties (TDCP), or a reference signal received power (RSRP).

[0275] In some example embodiments, at least the part of the PMI comprises at least one of: a set of beam indexes, a set of delay tap indexes, or a set of space-frequency coefficients constrained to a set of space-frequency indexes.

[0276] In some example embodiments, the network apparatus 110 is further caused to determine the CSI commonality level between the terminal apparatus and the one or more further terminal apparatuses based on at least one of: historical CSIs reported from the terminal apparatus and the one or more further terminal apparatuses, instantaneous CSIs reported from the terminal apparatus and the one or more further terminal apparatuses, channel characteristics of the terminal apparatus and the one or more further terminal apparatuses, locations of the terminal apparatus and the one or more further terminal apparatuses, or mobility of the terminal apparatus and the one or more further terminal apparatuses.

[0277] In some example embodiments, determining the CSI commonality level comprises: determining that the terminal apparatus and the one or more further terminal apparatuses share an at least partially common CSI based on determining that the terminal apparatus and the one or more further terminal apparatuses share a same CSI parameter value or different CSI parameter values satisfying a commonality condition.

[0278] In some example embodiments, the network apparatus 110 is further caused to: in accordance with a determination that the terminal apparatus and the one or more further terminal apparatuses share the at least partially common CSI, transmit to the terminal apparatus, an indication of a role for CSI reporting, the role being a cluster member for group CSI reporting.

[0279] In some example embodiments, the network apparatus 110 is further caused to: transmit, to the terminal apparatus, a cluster indication of a cluster which the terminal apparatus belongs to, and the cluster indication indicates at least one of a cluster type or a cluster identifier.

[0280] In some example embodiments, the network apparatus is further caused to transmit, to the terminal apparatus, a role change indication of: a change of the role from a first cluster head to the cluster member, or a change of the role from the cluster member to a second cluster member or a second cluster head.

[0281] In some example embodiments, a terminal apparatus capable of performing any of the method 1000 (for example, the terminal apparatus 120 in FIG. 1) may comprise means for performing the respective operations of the method 1000. The means may be implemented in any suitable form. For example, the means may be implemented in a circuitry or software module. The terminal apparatus may be implemented as or included in the terminal apparatus 120 in FIG. 1.

[0282] In some example embodiments, the terminal apparatus 120 comprises means for receiving, from a network apparatus, a channel state information (CSI) report configuration indicating at least one of a CSI parameter to be reported or a CSI parameter to be not reported; means for determining, based on the CSI report configuration, a first CSI parameter to be reported and a second CSI parameter to be not reported; means for determining, whether the second CSI parameter is associated with a determination of the first CSI parameter; in accordance with a determination that the second CSI parameter is associated with the determination of the first CSI parameter, means for determining the first CSI parameter based on a channel measurement by determining the second CSI parameter, or means for determining the first CSI parameter based on a CSI calculation capability of the terminal apparatus and a channel measurement without determining the second CSI parameter; and means for transmitting, to the network apparatus, a CSI report including the first CSI parameter and not including the second CSI parameter.

[0283] In some example embodiments, the terminal apparatus 120 may further comprise means for transmitting the CSI calculation capability to the network apparatus, and the CSI report configuration is received from the network apparatus based on the CSI calculation capability.

[0284] In some example embodiments, the means for determining the first CSI parameter based on the channel measurement by determining the second CSI parameter comprises: means for determining the second CSI parameter by using a complexity- reduced calculation method associated with the CSI calculation capability of the terminal apparatus.

[0285] In some example embodiments, the first CSI parameter or the second CSI parameter comprises at least a part of one of: a precoding matrix indicator (PMI), a channel quality indicator (CQI), a rank indicator (RI), time domain channel properties (TDCP), or a reference signal received power (RSRP).

[0286] In some example embodiments, at least the part of the PMI comprises at least one of: a set of beam indexes, a set of delay tap indexes, or a set of space-frequency coefficients constrained to a set of space-frequency indexes.

[0287] In some example embodiments, the terminal apparatus is further caused to: means for receiving, from the network apparatus, an indication of a role for CSI reporting.

[0288] In some example embodiments, the terminal apparatus is further caused to: means for receiving, from the network apparatus, a cluster indication of a cluster which the terminal apparatus belongs to, and the cluster indication indicates at least one of a cluster type or a cluster identifier.

[0289] In some example embodiments, the cluster indication indicates that the cluster which the terminal apparatus belongs to is a fully common cluster, a partially common cluster, or a fully non-common cluster.

[0290] In some example embodiments, the terminal apparatus 120 may further comprise: means for in accordance with a determination that the cluster is the partially common cluster and the role is a cluster member for group CSI reporting, determining to transmit a partial CSI report to the network apparatus based on the at least one of the CSI parameter to be reported or the CSI parameter to be not reported.

[0291] In some example embodiments, the terminal apparatus 120 may further comprise: means for receiving, from the network apparatus, a role change indication of: a change of the role from a first cluster head to a first cluster member, or a change of the role from a first cluster member to a second cluster member or a second cluster head.

[0292] In some example embodiments, a network apparatus capable of performing any of the method 1100 (for example, the network apparatus 110 in FIG. 1) may comprise means for performing the respective operations of the method 1100. The means may be implemented in any suitable form. For example, the means may be implemented in a circuitry or software module. The network apparatus may be implemented as or included in the network apparatus 110 in FIG. 1.

[0293] In some example embodiments, the network apparatus 110 comprises means for determining, for a terminal apparatus, a channel state information (CSI) report configuration based on a CSI commonality level between the terminal apparatus and one or more further terminal apparatuses, the CSI report configuration indicating at least one of a CSI parameter to be reported or a CSI parameter to be not reported; means for transmitting the CSI report configuration to the terminal apparatus; and means for receiving a CSI report from the terminal apparatus.

[0294] In some example embodiments, the network apparatus 110 may further comprise: means for receiving a CSI calculation capability from the terminal apparatus, and the means for determining the CSI report configuration based on the CSI commonality level comprises: means for determining, for the terminal apparatus, a first CSI parameter to be reported and a second CSI parameter to be not reported based on the CSI commonality level; and means for determining the at least one of the CSI parameter to be reported or the CSI parameter to be not reported based on the CSI calculation capability and the first CSI parameter to be reported and the second CSI parameter to be not reported.

[0295] In some example embodiments, the means for determining the at least one of the CSI parameter to be reported or the CSI parameter to be not reported based on the CSI calculation capability and the first CSI parameter to be reported and the second CSI parameter to be not reported comprises: means for in accordance with a determination that the CSI calculation capability indicates that the terminal apparatus is capable of determining the first CSI parameter without determining the second CSI parameter, determining that the CSI report configuration indicates there is no need to report the second CSI parameter.

[0296] In some example embodiments, the means for determining the at least one of the CSI parameter to be reported or the CSI parameter to be not reported based on the CSI calculation capability and the first CSI parameter to be reported and the second CSI parameter to be not reported comprises: means for in accordance with a determination that the second CSI parameter is associated with a determination of the first CSI parameter, and the CSI calculation capability indicates that the terminal apparatus is capable of determining the first CSI parameter by determining the second CSI parameter using a complexity-reduced calculation method, determining that the CSI report configuration indicates there is no need to report the second CSI parameter.

[0297] In some example embodiments, the at least one of the CSI parameter to be reported or the CSI parameter to be not reported comprises at least a part of one of: a precoding matrix indicator (PMI), a channel quality indicator (CQI), a rank indicator (RI), time domain channel properties (TDCP), or a reference signal received power (RSRP).

[0298] In some example embodiments, at least the part of the PMI comprises at least one of: a set of beam indexes, a set of delay tap indexes, or a set of space-frequency coefficients constrained to a set of space-frequency indexes.

[0299] In some example embodiments, the network apparatus 110 may further comprise: means for determining the CSI commonality level between the terminal apparatus and the one or more further terminal apparatuses based on at least one of: historical CSIs reported from the terminal apparatus and the one or more further terminal apparatuses, instantaneous CSIs reported from the terminal apparatus and the one or more further terminal apparatuses, channel characteristics of the terminal apparatus and the one or more further terminal apparatuses, locations of the terminal apparatus and the one or more further terminal apparatuses, or mobility of the terminal apparatus and the one or more further terminal apparatuses.

[0300] In some example embodiments, the means for determining the CSI commonality level comprises: means for determining that the terminal apparatus and the one or more further terminal apparatuses share an at least partially common CSI based on determining that the terminal apparatus and the one or more further terminal apparatuses share a same CSI parameter value or different CSI parameter values satisfying a commonality condition.

[0301] In some example embodiments, the network apparatus 110 may further comprise: means for in accordance with a determination that the terminal apparatus and the one or more further terminal apparatuses share the at least partially common CSI, transmitting to the terminal apparatus, an indication of a role for CSI reporting, the role being a cluster member for group CSI reporting.

[0302] In some example embodiments, the network apparatus 110 may further comprise: means for transmitting, to the terminal apparatus, a cluster indication of a cluster which the terminal apparatus belongs to, and the cluster indication indicates at least one of a cluster type or a cluster identifier.

[0303] In some example embodiments, the network apparatus 110 may further comprise: means for transmitting, to the terminal apparatus, a role change indication of: a change of the role from a first cluster head to the cluster member, or a change of the role from the cluster member to a second cluster member or a second cluster head.

[0304] FIG. 12 shows a flowchart of an example method 1200 implemented at a terminal apparatus in accordance with some example embodiments of the present disclosure. For the purpose of discussion, the method 1200 will be described from the perspective of the terminal apparatus 120 in FIG. 1.

[0305] At block 1210, the terminal apparatus 120 receives, from a network apparatus, a channel state information (CSI) report configuration indicating a reference CSI.

[0306] At block 1220, the terminal apparatus 120 determines, based on the CSI report configuration, a representation format of a CSI report, wherein the representation format indicates at least one CSI parameter to be reported and at least one format corresponding to the at least one parameter to be reported.

[0307] At block 1230, the terminal apparatus 120 generates the CSI report based on the determined representation format and a channel measurement.

[0308] At block 1240, the terminal apparatus 120 transmits the CSI report to the network apparatus.

[0309] In some example embodiments, the reference CSI comprises at least one of: a reference CSI parameter, information to be reported in association with a CSI parameter, a part of a CSI parameter, or a full CSI report.

[0310] In some example embodiments, the at least one format comprises one of: a differential value, an absolute value, an absolute coefficient, a differential coefficient, or a flag.

[0311] In some example embodiments, determining, based on the CSI report configuration, the representation format of the CSI report comprises: determining the representation format of the CSI report based on at least one of the reference CSI or information other than the reference CSI indicated in the CSI report configuration.

[0312] In some example embodiments, the reference CSI comprises a reference CSI parameter, and generating the CSI report based on the determined representation formatand the channel measurement comprises: determining, based on the channel measurement, a differential value with respect to the reference CSI parameter; and generating the CSI report based on the differential value.

[0313] In some example embodiments, the reference CSI comprises information to be reported in association with a CSI parameter, and generating the CSI report based on the determined representation format and the channel measurement comprises: determining, based on the channel measurement and the information, a differential or absolute coefficient of the CSI parameter associated with the information; and generating the CSI report based on the differential or absolute coefficient of the CSI parameter.

[0314] In some example embodiments, the information to be reported in association with the CSI parameter comprises an indication of at least one of: a set of beams, a set of subbands, or a set of delay taps.

[0315] In some example embodiments, determining, based on the CSI report configuration, the representation format of the CSI report comprises: in accordance with a determination that the reference CSI is a full CSI report, determining that the representation format of the CSI report is a differential CSI report with respect to the full CSI report; and determining the at least one CSI parameter to be reported and the at least one format corresponding to the at least one parameter to be reported based on CSI parameters and formats of the CSI parameters in the full CSI report.

[0316] In some example embodiments, the reference CSI is determined based on at least one of: a historic CSI, an instantaneous CSI, a predefined CSI, or a CSI commonality level between the terminal apparatus and one or more further terminal apparatuses.

[0317] In some example embodiments, the terminal apparatus is further caused to: receiving, from the network apparatus, an indication of a role for CSI reporting.

[0318] In some example embodiments, the terminal apparatus is further caused to: receiving, from the network apparatus, a cluster indication of a cluster which the terminal apparatus belongs to, and the cluster indication indicates at least one of a cluster type or a cluster identifier.

[0319] In some example embodiments, the cluster indication indicates that the cluster which the terminal apparatus belongs to is a fully common cluster, a partially common cluster, or a fully non-common cluster.

[0320] In some example embodiments, the terminal apparatus is further caused to: in accordance with a determination that the cluster is the partially common cluster and the role is a cluster member for group CSI reporting, determining to transmit a partial CSI report to the network apparatus based on the reference CSI.

[0321] In some example embodiments, the terminal apparatus is further caused to receive a role change indication of: a change of the role from a first cluster head to a first cluster member, or a change of the role from a first cluster member to a second cluster member or a second cluster head.

[0322] FIG. 13 shows a flowchart of an example method 1300 implemented at a network apparatus in accordance with some example embodiments of the present disclosure. For the purpose of discussion, the method 1300 will be described from the perspective of the network apparatus 110 in FIG. 1.

[0323] At block 1310, the network apparatus 110 determines a channel state information (CSI) report configuration indicating a reference CSI.

[0324] At block 1320, the network apparatus 110 transmits the CSI report configuration to a terminal apparatus.

[0325] At block 1330, the network apparatus 110 receives, from the terminal apparatus, a CSI report in a representation format associated with the CSI report configuration.

[0326] In some example embodiments, the reference CSI comprises at least one of: a reference CSI parameter, information to be reported in association with a CSI parameter, a part of a CSI parameter, or a full CSI report.

[0327] In some example embodiments, the information to be reported in association with the CSI parameter comprises an indication of at least one of: a set of beams, a set of subbands, or a set of delay taps.

[0328] In some example embodiments, the CSI report in the representation format comprises a CSI parameter represented in a format of a differential value, an absolute value, an absolute coefficient, a differential coefficient, or a flag.

[0329] In some example embodiments, determining the CSI report configuration indicating the reference CSI comprises: determining the reference CSI based on at least one of a historic CSI, an instantaneous CSI, a predefined CSI, or a CSI commonality levelbetween the terminal apparatus and one or more further terminal apparatuses.

[0330] In some example embodiments, the network apparatus 110 is further caused to determine the CSI commonality level between the terminal apparatus and the one or more further terminal apparatuses based on at least one of: historical CSIs reported from the terminal apparatus and the one or more further terminal apparatuses, instantaneous CSIs reported from the terminal apparatus and the one or more further terminal apparatuses, channel characteristics of the terminal apparatus and the one or more further terminal apparatuses, locations of the terminal apparatus and the one or more further terminal apparatuses, or mobility of the terminal apparatus and the one or more further terminal apparatuses.

[0331] In some example embodiments, determining the CSI commonality level comprises: determining that the terminal apparatus and the one or more further terminal apparatuses share an at least partially common CSI based on determining that the terminal apparatus and the one or more further terminal apparatuses share a same CSI parameter value or different CSI parameter values satisfying a commonality condition.

[0332] In some example embodiments, the network apparatus 110 is further caused to: in accordance with a determination that the terminal apparatus and the one or more further terminal apparatuses share the at least partially common CSI, transmitting to the terminal apparatus, an indication of a role for CSI reporting, the role being a cluster member for group CSI reporting.

[0333] In some example embodiments, determining the CSI report configuration indicating the reference CSI comprises: determining the reference CSI based on a full CSI report of a further terminal apparatus being a cluster head corresponding to the cluster member for group CSI reporting.

[0334] In some example embodiments, the network apparatus 110 is further caused to: transmitting, to the terminal apparatus, a cluster indication of a cluster which the terminal apparatus belongs to, and the cluster indication indicates at least one of a cluster type or a cluster identifier.

[0335] In some example embodiments, the network apparatus is further caused to transmit, to the terminal apparatus, a role change indication of: a change of the role from a first cluster head to the cluster member, or a change of the role from the cluster memberto a second cluster member or a second cluster head.

[0336] In some example embodiments, a terminal apparatus capable of performing any of the method 1200 (for example, the terminal apparatus 120 in FIG. 1) may comprise means for performing the respective operations of the method 1200. The means may be implemented in any suitable form. For example, the means may be implemented in a circuitry or software module. The terminal apparatus may be implemented as or included in the terminal apparatus 120 in FIG. 1.

[0337] In some example embodiments, the terminal apparatus 120 comprises means for receiving, from a network apparatus, a channel state information (CSI) report configuration indicating a reference CSI; means for determining, based on the CSI report configuration, a representation format of a CSI report, wherein the representation format indicates at least one CSI parameter to be reported and at least one format corresponding to the at least one parameter to be reported; means for generating the CSI report based on the determined representation format and a channel measurement; and means for transmitting the CSI report to the network apparatus.

[0338] In some example embodiments, the reference CSI comprises at least one of: a reference CSI parameter, information to be reported in association with a CSI parameter, a part of a CSI parameter, or a full CSI report.

[0339] In some example embodiments, the at least one format comprises one of: a differential value, an absolute value, an absolute coefficient, a differential coefficient, or a flag.

[0340] In some example embodiments, the means for determining, based on the CSI report configuration, the representation format of the CSI report comprises: means for determining the representation format of the CSI report based on at least one of the reference CSI or information other than the reference CSI indicated in the CSI report configuration.

[0341] In some example embodiments, the reference CSI comprises a reference CSI parameter, and the means for generating the CSI report based on the determined representation format and the channel measurement comprises: means for determining, based on the channel measurement, a differential value with respect to the reference CSI parameter; and generating the CSI report based on the differential value.

[0342] In some example embodiments, the reference CSI comprises information to be reported in association with a CSI parameter, and the means for generating the CSI report based on the determined representation format and the channel measurement comprises: means for determining, based on the channel measurement and the information, a differential or absolute coefficient of the CSI parameter associated with the information; and means for generating the CSI report based on the differential or absolute coefficient of the CSI parameter.

[0343] In some example embodiments, the information to be reported in association with the CSI parameter comprises an indication of at least one of: a set of beams, a set of subbands, or a set of delay taps.

[0344] In some example embodiments, the means for determining, based on the CSI report configuration, the representation format of the CSI report comprises: means for in accordance with a determination that the reference CSI is a full CSI report, determining that the representation format of the CSI report is a differential CSI report with respect to the full CSI report; and means for determining the at least one CSI parameter to be reported and the at least one format corresponding to the at least one parameter to be reported based on CSI parameters and formats of the CSI parameters in the full CSI report.

[0345] In some example embodiments, the reference CSI is determined based on at least one of: a historic CSI, an instantaneous CSI, a predefined CSI, or a CSI commonality level between the terminal apparatus and one or more further terminal apparatuses.

[0346] In some example embodiments, the terminal apparatus 120 may further comprise: means for receiving, from the network apparatus, an indication of a role for CSI reporting.

[0347] In some example embodiments, the terminal apparatus 120 may further comprise: means for receiving, from the network apparatus, a cluster indication of a cluster which the terminal apparatus belongs to, and the cluster indication indicates at least one of a cluster type or a cluster identifier.

[0348] In some example embodiments, the cluster indication indicates that the cluster which the terminal apparatus belongs to is a fully common cluster, a partially common cluster, or a fully non-common cluster.

[0349] In some example embodiments, the terminal apparatus 120 may further comprise: means for in accordance with a determination that the cluster is the partially commoncluster and the role is a cluster member for group CSI reporting, determining to transmit a partial CSI report to the network apparatus based on the reference CSI.

[0350] In some example embodiments, the terminal apparatus 120 may further comprise: means for receiving a role change indication of: a change of the role from a first cluster head to a first cluster member, or a change of the role from a first cluster member to a second cluster member or a second cluster head.

[0351] In some example embodiments, a network apparatus capable of performing any of the method 1300 (for example, the network apparatus 110 in FIG. 1) may comprise means for performing the respective operations of the method 1300. The means may be implemented in any suitable form. For example, the means may be implemented in a circuitry or software module. The network apparatus may be implemented as or included in the network apparatus 110 in FIG. 1.

[0352] In some example embodiments, the network apparatus 110 comprises means for determining a channel state information (CSI) report configuration indicating a reference CSI; means for transmitting the CSI report configuration to a terminal apparatus; and means for receiving, from the terminal apparatus, a CSI report in a representation format associated with the CSI report configuration.

[0353] In some example embodiments, the reference CSI comprises at least one of: a reference CSI parameter, information to be reported in association with a CSI parameter, a part of a CSI parameter, or a full CSI report.

[0354] In some example embodiments, the information to be reported in association with the CSI parameter comprises an indication of at least one of: a set of beams, a set of subbands, or a set of delay taps.

[0355] In some example embodiments, the CSI report in the representation format comprises a CSI parameter represented in a format of a differential value, an absolute value, an absolute coefficient, a differential coefficient, or a flag.

[0356] In some example embodiments, the means for determining the CSI report configuration indicating the reference CSI comprises: means for determining the reference CSI based on at least one of a historic CSI, an instantaneous CSI, a predefined CSI, or a CSI commonality level between the terminal apparatus and one or more further terminal apparatuses.

[0357] In some example embodiments, the network apparatus 110 may further comprise: means for determining the CSI commonality level between the terminal apparatus and the one or more further terminal apparatuses based on at least one of: historical CSIs reported from the terminal apparatus and the one or more further terminal apparatuses, instantaneous CSIs reported from the terminal apparatus and the one or more further terminal apparatuses, channel characteristics of the terminal apparatus and the one or more further terminal apparatuses, locations of the terminal apparatus and the one or more further terminal apparatuses, or mobility of the terminal apparatus and the one or more further terminal apparatuses.

[0358] In some example embodiments, the means for determining the CSI commonality level comprises: means for determining that the terminal apparatus and the one or more further terminal apparatuses share an at least partially common CSI based on determining that the terminal apparatus and the one or more further terminal apparatuses share a same CSI parameter value or different CSI parameter values satisfying a commonality condition.

[0359] In some example embodiments, the network apparatus 110 may further comprise: means for in accordance with a determination that the terminal apparatus and the one or more further terminal apparatuses share the at least partially common CSI, transmitting to the terminal apparatus, an indication of a role for CSI reporting, the role being a cluster member for group CSI reporting.

[0360] In some example embodiments, the means for determining the CSI report configuration indicating the reference CSI comprises: means for determining the reference CSI based on a full CSI report of a further terminal apparatus being a cluster head corresponding to the cluster member for group CSI reporting.

[0361] In some example embodiments, the network apparatus 110 may further comprise: means for transmitting, to the terminal apparatus, a cluster indication of a cluster which the terminal apparatus belongs to, and the cluster indication indicates at least one of a cluster type or a cluster identifier.

[0362] In some example embodiments, the network apparatus 110 may further comprise: means for transmitting, to the terminal apparatus, a role change indication of: a change of the role from a first cluster head to the cluster member, or a change of the role from the cluster member to a second cluster member or a second cluster head.

[0363] FIG. 14 is a simplified block diagram of a device 1400 that is suitable for implementing example embodiments of the present disclosure. The device 1400 may be provided to implement a communication device, for example, the terminal apparatus 120 or the network apparatus 110 as shown in FIG. 1. As shown, the device 1400 includes one or more processors 1410, one or more memories 1420 coupled to the processor 1410, and one or more communication modules 1440 coupled to the processor 1410.

[0364] The communication module 1440 is for bidirectional communications. The communication module 1440 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 1440 may include at least one antenna.

[0365] The processor 1410 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 1400 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.

[0366] The memory 1420 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) 1424, 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 randomaccess memory (RAM) 1422 and other volatile memories that will not last in the powerdown duration.

[0367] A computer program 1430 includes computer executable instructions that are executed by the associated processor 1410. The instructions of the program 1430 may include instructions for performing operations / acts of some example embodiments of the present disclosure. The program 1430 may be stored in the memory, e.g., the ROM 1424. The processor 1410 may perform any suitable actions and processing by loading the program 1430 into the RAM 1422.

[0368] The example embodiments of the present disclosure may be implemented by means of the program 1430 so that the device 1400 may perform any process of the disclosure as discussed with reference to FIG. 2 to FIG. 13. The example embodiments of the present disclosure may also be implemented by hardware or by a combination of software and hardware.

[0369] In some example embodiments, the program 1430 may be tangibly contained in a computer readable medium which may be included in the device 1400 (such as in the memory 1420) or other storage devices that are accessible by the device 1400. The device 1400 may load the program 1430 from the computer readable medium to the RAM 1422 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).

[0370] FIG. 15 shows an example of the computer readable medium 1500 which may be in form of CD, DVD or other optical storage disk. The computer readable medium 1500 has the program 1430 stored thereon.

[0371] 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.

[0372] 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 themethods 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. Machine-executable instructions for program modules may be executed within a local or distributed device. In a distributed device, program modules may be located in both local and remote storage media.

[0373] 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 other programmable 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.

[0374] 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.

[0375] 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 randomaccess memory (RAM), a read-only memory (ROM), an erasable programmable readonly memory (EPROM or Flash memory), an optical fiber, a portable compact disc readonly memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination of the foregoing.

[0376] 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 shownor 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 sub-combination.

[0377] 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 terminal apparatus comprising: at least one processor; and at least one memory storing instructions that, when executed by the at least one processor, cause the terminal apparatus to: receive, from a network apparatus, a channel state information (CSI) report configuration indicating a role for CSI reporting; in accordance with a determination that the role is a cluster head for group CSI reporting, transmit a full CSI report to the network apparatus based on the CSI report configuration; and in accordance with a determination that the role is a cluster member for group CSI reporting, transmit a partial CSI report or refrain from transmitting a CSI report to the network apparatus based on the CSI report configuration.

2. The terminal apparatus of claim 1, wherein the terminal apparatus is further caused to: determine the partial CSI report by refraining from including a common CSI parameter between the terminal apparatus and a further terminal apparatus in a same cluster.

3. The terminal apparatus of claim 2, wherein the common CSI parameter between the terminal apparatus and the further terminal apparatus is associated with a same CSI parameter value or different CSI parameter values satisfying a commonality condition.

4. The terminal apparatus of any of claims 1 to 3, wherein the terminal apparatus is further caused to: receive a reference CSI from the network apparatus; and in accordance with the determination that the role is the cluster member for group CSI reporting, determine the partial CSI report based on the reference CSI.

5. The terminal apparatus of claim 4, wherein the reference CSI comprises at least one of: a reference CSI parameter,information to be reported in association with a CSI parameter, a part of a CSI parameter, or a full CSI report.

6. The terminal apparatus of claim 5, wherein the information to be reported in association with the CSI parameter comprises an indication of at least one of: a set of beams, a set of sub-bands, or a set of delay taps.

7. The terminal apparatus of any of claims 1 to 3, wherein the terminal apparatus is further caused to: receive, from the network apparatus, at least one of a CSI parameter to be reported or a CSI parameter to be not reported; and in accordance with the determination that the role is the cluster member for group CSI reporting, determine the partial CSI report based on the at least one of the CSI parameter to be reported or the CSI parameter to be not reported.

8. The terminal apparatus of any of claims 1 to 7, wherein the terminal apparatus is further caused to: receive, from the network apparatus, a cluster indication of a cluster which the terminal apparatus belongs to, and the cluster indication indicates at least one of a cluster type or a cluster identifier.

9. The terminal apparatus of claim 8, wherein the cluster indication indicates that the cluster which the terminal apparatus belongs to is a fully common cluster, a partially common cluster, or a fully non-common cluster.

10. The terminal apparatus of claim 9, wherein the terminal apparatus is further caused to: in accordance with a determination that the cluster is the fully common cluster and the role is the cluster member for group CSI reporting, determine to refrain from transmitting a CSI report to the network apparatus; in accordance with a determination that the cluster is the partially common cluster and the role is the cluster member for group CSI reporting, determine to transmit the partial CSI report to the network apparatus; andin accordance with a determination that the cluster is the fully non-common cluster and the role is for non-common CSI reporting, determine to transmit a full CSI report to the network apparatus.

11. The terminal apparatus of any of claims 1 to 10, wherein the cluster head and the cluster member are associated with a same cluster or different clusters.

12. The terminal apparatus of any of claims 1 to 11, wherein the cluster head is a first cluster head associated with a first cluster, and the terminal apparatus is further caused to: receive a role change indication of: a change of the role from the first cluster head to a first cluster member, the first cluster member being associated with the first cluster or a further cluster different from the first cluster, or a change of the role from the first cluster head to a second cluster head associated with a second cluster different from the first cluster.

13. The terminal apparatus of any of claims 1 to 11, wherein the cluster member is a first cluster member associated with a first cluster and the terminal apparatus is further caused to: receive a role change indicating one of: a change of the role from the first cluster member to a second cluster member associated with a second cluster different from the first cluster, or a change of the role from the first cluster member to a cluster head associated with the first cluster or a second cluster different from the first cluster.

14. The terminal apparatus of any of claims 1 to 13, wherein the full CSI report or the partial CSI report comprises at least a part of one of: a precoding matrix indicator (PMI), a channel quality indicator (CQI), a rank indicator (RI), time domain channel proprieties (TDCP), or a reference signal received power (RSRP).

15. A network apparatus comprising: at least one processor; andat least one memory storing instructions that, when executed by the at least one processor, cause the network apparatus to: determine a CSI commonality level between a terminal apparatus and one or more further terminal apparatuses; determine, for the terminal apparatus, a role for CSI reporting based on the CSI commonality level; and transmit, to the terminal apparatus, a CSI report configuration indicating the role for CSI reporting.

16. The network apparatus of claim 15, wherein determining the CSI commonality level between the terminal apparatus and the one or more further terminal apparatuses comprises: in accordance with a determination that a common CSI parameter is present between the terminal apparatus and the one or more further terminal apparatuses, determining that the terminal apparatus and the one or more further terminal apparatuses share an at least partially common CSI; and in accordance with a determination that no common CSI parameter is present between the terminal apparatus and the one or more further terminal apparatuses, determining that the terminal apparatus and the one or more further terminal apparatuses share no common CSI.

17. The network apparatus of claim 16, wherein the common CSI parameter between the terminal apparatus and the one or more terminal apparatus is associated with a same CSI parameter value or different CSI parameter values satisfying a commonality condition.

18. The network apparatus of any of claims 17 to 18, wherein determining, for the terminal apparatus, the role for CSI reporting based on the CSI commonality level comprises: in accordance with a determination that the terminal apparatus and the one or more further terminal apparatuses share the at least partially common CSI, determining that the role for the terminal apparatus is one of: a cluster head for group CSI reporting configured to transmit a full CSI report, a cluster member for group CSI reporting configured to transmit a partial CSIreport, or a cluster member for group CSI reporting configured to refrain from transmitting a CSI report.

19. The network apparatus of claim 18, wherein determining the role for the terminal apparatus comprises determining whether the terminal apparatus is the cluster head or the cluster member based on at least one of:RSRP values of the terminal apparatus and the one or more further terminal apparatuses, distances between the terminal apparatus and the one or more further terminal apparatuses, distances between the terminal apparatus and the network apparatus, a rotation rule for a cluster, or a predefined characteristic or capability of the terminal apparatus and the one or more further terminal apparatuses20. The network apparatus of claim 16, wherein determining, for the terminal apparatus, the role for CSI reporting based on the CSI commonality level comprises: in accordance with a determination that the terminal apparatus and the one or more further terminal apparatuses share no common CSI, determining that the role for the terminal apparatus is a role for non-common CSI reporting configured to transmit a full CSI report.

21. The network apparatus of any of claims 15 to 20, wherein determining the CSI commonality level between the terminal apparatus and the one or more further terminal apparatuses comprises determining the CSI commonality level based on at least one of: historical CSIs reported from the terminal apparatus and the one or more further terminal apparatuses, instantaneous CSIs reported from the terminal apparatus and the one or more further terminal apparatuses, channel characteristics of the terminal apparatus and the one or more further terminal apparatuses, locations of the terminal apparatus and the one or more further terminal apparatuses, ormobility of the terminal apparatus and the one or more further terminal apparatuses.

22. The network apparatus of any of claims 15 to 21, wherein the network apparatus is further caused to transmit to the terminal apparatus an indication of a change of the role for CSI reporting.

23. The network apparatus of any of claims 15 to 22, wherein the network apparatus is further caused to: transmit to the terminal apparatus, a cluster indication of a cluster which the terminal apparatus belongs to, and the cluster indication indicates at least one of a cluster type or a cluster identifier.

24. The network apparatus of claim 23, wherein the cluster indication indicates that the cluster which the terminal apparatus belongs to is one of a fully common cluster, a partially common cluster, or a fully non-common cluster.

25. The network apparatus of any of claims 15 to 24, wherein the network apparatus is further caused to transmit, to the terminal apparatus, at least one of: a reference CSI, or at least one of a CSI parameter to be reported or a CSI parameter to be not reported.

26. A method comprising: receiving, at a terminal apparatus and from a network apparatus, a channel state information (CSI) report configuration indicating a role for CSI reporting; in accordance with a determination that the role is a cluster head for group CSI reporting, transmitting a full CSI report to the network apparatus based on the CSI report configuration; and in accordance with a determination that the role is a cluster member for group CSI reporting, transmitting a partial CSI report or refrain from transmitting a CSI report to the network apparatus based on the CSI report configuration.

27. A method comprising: determining, at a network apparatus, a CSI commonality level between a terminalapparatus and one or more further terminal apparatuses; determining, for the terminal apparatus, a role for CSI reporting based on the CSI commonality level; and transmitting, to the terminal apparatus, a CSI report configuration indicating the role for CSI reporting.

28. A terminal apparatus comprising: means for receiving, from a network apparatus, a channel state information (CSI) report configuration indicating a role for CSI reporting; means for in accordance with a determination that the role is a cluster head for group CSI reporting, transmitting a full CSI report to the network apparatus based on the CSI report configuration; and means for in accordance with a determination that the role is a cluster member for group CSI reporting, transmitting a partial CSI report or refrain from transmitting a CSI report to the network apparatus based on the CSI report configuration.

29. A network apparatus comprising: means for determining a CSI commonality level between a terminal apparatus and one or more further terminal apparatuses; means for determining, for the terminal apparatus, a role for CSI reporting based on the CSI commonality level; and means for transmitting, to the terminal apparatus, a CSI report configuration indicating the role for CSI reporting.

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

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