Quality indicator feedback

Abstract

Example embodiments of the present disclosure are directed to quality indicator feedback. A method comprises determining, at a terminal apparatus, a plurality of quality indicator values corresponding to a plurality of layers; compressing the plurality of quality indicator values based on layer distribution information and an order of the plurality of quality indicator values; and transmitting, to a network apparatus, information associated with the compression comprising the plurality of compressed quality indicator values corresponding to the plurality of layers.

Description

QUALITY INDICATOR FEEDBACKRELATED APPLICATION

[0001] This application claims priority to US provisional Application No. 63 / 733282 filed December 12, 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 telecommunication and in particular, to methods, devices, apparatuses and computer readable storage medium for quality indicator feedback.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. A communication device may be provided with a service by an application server.

[0004] The communication network may operate in accordance with standards such as those provided by Third Generation Partnership Project (3 GPP) 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

[0005] 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: determine a plurality of quality indicator values corresponding to a plurality of layers; compress the plurality of quality indicator values based on layer distribution information and an order of the plurality of quality indicator values; and transmit, to a network apparatus, information associated with the compression comprising the plurality of compressed quality indicator values corresponding to the plurality of layers.

[0006] 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: receive, from a terminal apparatus, information associated with compression comprising a plurality of compressed quality indicator values corresponding to a plurality of layers; and decompress, based on the information associated with the compression, the plurality of compressed quality indicator values to determine a plurality of quality indicator values corresponding to the plurality of layers.

[0007] In a third aspect of the present disclosure, there is provided a method. The method comprises: determining a plurality of quality indicator values corresponding to a plurality of layers; compressing the plurality of quality indicator values based on layer distribution information and an order of the plurality of quality indicator values; and transmitting, to a network apparatus, information associated with the compression comprising the plurality of compressed quality indicator values corresponding to the plurality of layers.

[0008] In a fourth aspect of the present disclosure, there is provided a method. The method comprises: receiving, from a terminal apparatus, information associated with compression comprising a plurality of compressed quality indicator values corresponding to a plurality of layers; and decompressing, based on the information associated with the compression, the plurality of compressed quality indicator values to determine a plurality of quality indicator values corresponding to the plurality of layers.

[0009] In a fifth aspect of the present disclosure, there is provided a terminal apparatus. The terminal apparatus comprises means for determining a plurality of quality indicator values corresponding to a plurality of layers; means for compressing the plurality of quality indicator values based on layer distribution information and an order of the plurality of quality indicator values; and means for transmitting, to a network apparatus, information associated with the compression comprising the plurality of compressed quality indicator values corresponding to the plurality of layers.

[0010] In a sixth aspect of the present disclosure, there is provided a network apparatus. The network apparatus comprises means for receiving, from a terminal apparatus, information associated with compression comprising a plurality of compressed qualityindicator values corresponding to a plurality of layers; and means for decompressing, based on the information associated with the compression, the plurality of compressed quality indicator values to determine a plurality of quality indicator values corresponding to the plurality of layers.

[0011] 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 or fourth aspect.

[0012] 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: determine a plurality of quality indicator values corresponding to a plurality of layers; compress the plurality of quality indicator values based on binning of the plurality of quality indicator values; and transmit, to a network apparatus, information associated with the compression comprising at least one of the plurality of compressed quality indicator values corresponding to the plurality of layers.

[0013] 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: receive, from a terminal apparatus, information associated with compression comprising at least one of a plurality of compressed quality indicator values corresponding to a plurality of layers; and decompress, based on the information associated with the compression, the plurality of compressed quality indicator values to determine a plurality of quality indicator values corresponding to the plurality of layers.

[0014] In a tenth aspect of the present disclosure, there is provided a method. The method comprises: determining a plurality of quality indicator values corresponding to a plurality of layers; compressing the plurality of quality indicator values based on binning of the plurality of quality indicator values; and transmitting, to a network apparatus, information associated with the compression comprising at least one of the plurality of compressed quality indicator values corresponding to the plurality of layers.

[0015] In an eleventh aspect of the present disclosure, there is provided a method. Themethod comprises: receiving, from a terminal apparatus, information associated with compression comprising at least one of a plurality of compressed quality indicator values corresponding to a plurality of layers; and decompressing, based on the information associated with the compression, the plurality of compressed quality indicator values to determine a plurality of quality indicator values corresponding to the plurality of layers.

[0016] In a twelfth aspect of the present disclosure, there is provided a terminal apparatus. The terminal apparatus comprises means for determining a plurality of quality indicator values corresponding to a plurality of layers; means for compressing the plurality of quality indicator values based on binning of the plurality of quality indicator values; and means for transmitting, to a network apparatus, information associated with the compression comprising at least one of the plurality of compressed quality indicator values corresponding to the plurality of layers.

[0017] In a thirteenth aspect of the present disclosure, there is provided a network apparatus. The network apparatus comprises means for receiving, from a terminal apparatus, information associated with compression comprising at least one of a plurality of compressed quality indicator values corresponding to a plurality of layers; and means for decompressing, based on the information associated with the compression, the plurality of compressed quality indicator values to determine a plurality of quality indicator values corresponding to the plurality of layers.

[0018] 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.

[0019] 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 will become easily comprehensible through the following description.BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Some example embodiments will now be described with reference to the accompanying drawings, where:

[0021] FIG. 1A illustrates a schematic graph of link performance in a case with a layer quality imbalance;

[0022] FIG. IB illustrates a schematic graph of different scenarios with increasing postequalizer layer imbalance between layers;

[0023] FIG. 2 illustrates an example communication environment in which example embodiments of the present disclosure can be implemented;

[0024] FIG. 3 illustrates a signaling flow of an example process for quality indicator feedback in accordance with some example embodiments of the present disclosure;

[0025] FIGS. 4 A, 4B and 4C illustrate schematic diagrams of example quality imbalance patterns in accordance with some example embodiments of the present disclosure;

[0026] FIGS. 5A, 5B and 5C illustrate example sets of numbers of bits for compressing the quality indicator values in accordance with some example embodiments of the present disclosure;

[0027] FIG. 6 illustrates example layer sorting information (LSI) for different numbers of layers in accordance with some example embodiments of the present disclosure;

[0028] FIG. 7 illustrates a signaling flow of an example process for CSI signaling in accordance with some example embodiments of the present disclosure;

[0029] FIG. 8 illustrates a signaling flow of another example process for quality indicator feedback in accordance with some example embodiments of the present disclosure;

[0030] FIG. 9 illustrates a schematic diagram of an example of binning of a reference range in accordance with some example embodiments of the present disclosure;

[0031] FIG. 10 illustrates schematic diagrams of other examples of binning of a reference range in accordance with some example embodiments of the present disclosure;

[0032] FIG. 11 illustrates a signaling flow of another example process for CSI signaling in accordance with some example embodiments of the present disclosure;

[0033] FIG. 12 illustrates schematic diagrams of examples of a CSI report quantity in accordance with some example embodiments of the present disclosure;

[0034] FIG. 13 illustrates a flowchart of a method implemented at a terminal apparatus in accordance with some example embodiments of the present disclosure;

[0035] FIG. 14 illustrates a flowchart of a method implemented at a network apparatus in accordance with some example embodiments of the present disclosure;

[0036] FIG. 15 illustrates a flowchart of a method implemented at a terminal apparatus in accordance with some example embodiments of the present disclosure;

[0037] FIG. 16 illustrates a flowchart of a method implemented at a network apparatus in accordance with some example embodiments of the present disclosure;

[0038] FIG. 17 illustrates a simplified block diagram of a device that is suitable for implementing example embodiments of the present disclosure; and

[0039] FIG. 18 illustrates a block diagram of an example computer readable medium in accordance with some example embodiments of the present disclosure.

[0040] Throughout the drawings, the same or similar reference numerals represent the same or similar element.DETAILED DESCRIPTION

[0041] 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.

[0042] 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.

[0043] 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 particularfeature, 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.

[0044] It shall be understood that although the terms “first,” “second,”..., etc. in front of noun(s) and the like may be used herein to describe various elements, these elements should not be limited by these terms. These terms are only used to distinguish one element from another and they do not limit the order of the noun(s). For example, a first element could be termed a second element, and similarly, a second element could be termed a first element, without departing from the scope of example embodiments. As used herein, the term “and / or” includes any and all combinations of one or more of the listed terms.

[0045] 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.

[0046] 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.

[0047] 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.

[0048] As used in this application, the term “circuitry” may refer to one or more or all of the following:(a) hardware-only circuit implementations (such as implementations in only analog and / or digital circuitry) and(b) combinations of hardware circuits and software, such as (as applicable):(i) a combination of analog and / or digital hardware circuit(s) with software / firmware and(ii) any portions of hardware processor(s) with software (including digital signal processor(s)), software, and memory(ies) that work together to cause an apparatus, such as a mobile phone or server, to perform various functions) and(c) hardware circuit(s) and or processor(s), such as a microprocessor(s) or a portion of a microprocessor(s), that requires software (e.g., firmware) for operation, but the software may not be present when it is not needed for operation.

[0049] 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.

[0050] 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 befuture 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.

[0051] As used herein, the term “network device” refers to a node in a communication network via which a terminal device accesses the network and receives services therefrom. The network device may refer to a base station (BS) or an access point (AP), for example, a node B (NodeB or NB), an evolved NodeB (eNodeB or eNB), an NR NB (also referred to as a gNB), a Remote Radio Unit (RRU), a radio header (RH), a remote radio head (RRH), a relay, an Integrated Access and Backhaul (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 Centralized Unit (CU) and a Distributed Unit (DU) at an IAB donor node. An IAB node comprises a Mobile Terminal (IAB-MT) part that behaves like a UE toward the parent node, and a DU part of an IAB node behaves like a base station toward the next-hop IAB node.

[0052] The term “terminal device” refers to any end device that may be capable of wireless communication. By way of example rather than limitation, a terminal device may also be referred to as a communication device, user equipment (UE), a Subscriber Station (SS), a Portable Subscriber Station, a Mobile Station (MS), or an Access Terminal (AT). The terminal device may include, but not limited to, a mobile phone, a cellular phone, a smart phone, voice over IP (VoIP) phones, wireless local loop phones, a tablet, a wearable terminal device, a personal digital assistant (PDA), portable computers, desktop computer, image capture terminal devices such as digital cameras, gaming terminal devices, music storage and playback appliances, vehicle-mounted wireless terminal devices, wireless endpoints, mobile stations, laptop-embedded equipment (LEE), laptop-mounted equipment (LME), USB dongles, smart devices, wireless customer-premises equipment (CPE), an Internet of Things (loT) device, a watch or other wearable, a head-mounted display (HMD), a vehicle, a drone, a medical device and applications (e.g., remote surgery), an industrial device and applications (e.g., a robot and / or other wireless devices operating in an industrial and / or an automated processing chain contexts), a consumerelectronics 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.

[0053] 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.

[0054] Currently, various schemes of codeword-to-layer mapping are under investigation. For example, nowadays 5G smartphones may support up to 4 layers in downlink (DL) multiple input multiple output (MIMO) communications, and the 3GPP specifications support up to 8 layers. Current 5G NR standard limits physical downlink shared channel (PDSCH) transmission with up to 4 layers to a single codeword and only applies 2 codewords in case of more than 4 (i.e. 5 to 8) layers although LTE supported the use of 2 codewords starting from 2 layers (up to 8 layers). That is, in current 5G NR standard, until 4 layers, only one codeword is supported, with all information bits equally distributed to all layers.

[0055] However, having a single codeword mapped to up to 4 layers may have a negative impact on throughput performance in scenarios where the propagation environment creates a large quality imbalance, e.g., a large signal-to-interference-plus-noise ratio (SINR) imbalance between MIMO layers. This imbalance may happen due to the radio channel or the UE antennas’ placement and directional nature, leading them to exhibit different gains towards the gNodeB antennas. In uplink this imbalance may be further aggravated by the user blocking some of the antennas while gripping the phone orchanging the phone’s orientation.

[0056] To reduce this negative impact, link adaptation may be employed. Specifically, the gNodeB may dynamically adjust the DL transmission based on the channel state information (CSI) measured and reported by the UE. For example, the gNodeB may first transmit DL reference signals (RS) such as non-zero power (NZP) CSI RS for the UE to measure the radio channel and the SINR. The UE may use these signals for CSI acquisition of parameters such as rank indicator (RI), precoder matrix indicator (PMI) and channel quality indicator (CQI). These parameters may be reported back to the gNodeB as the UE’s recommendation on the number of layers to transmit, precoder, and modulation and coding scheme (MCS) to maximize link capacity. The gNodeB may use this information to adapt the PDSCH transmission configuration, ensuring that the connection is maintained despite changes in the instantaneous link conditions.

[0057] When reporting these CSI parameters for quality indicator feedback, a reporting quantity “cri-RI-LI-PMI-CQ may be used. The UE may select a preferred CSI resource, typically based on the received signal strength of all the resources, indicated by CSI resource indicator (CRI). Using the NZP CSI-RS resource the UE may obtain the channel estimation and SINR levels and use these to select the best number of layers v to maximize link capacity, indicated by the rank indicator (RI). The UE may use the selected rank / number of layers v to choose the best precoder matrix, indicated by PMI, PG CWpxr, where Np is the total number of CSI-RS antenna ports and v is the number of layers indicated by RI. For a combination of CRI, RI and PMI, the UE may calculate the SINR level per MIMO layer and choose one CQI value (or index) to maximize capacity throughout the layers for a target block error rate (BLER), such as 0.1. Then this information may be used to select the column (i.e. layer) in the precoding matrix belonging to the strongest layer of the codeword, indicated by layer indicator (LI).

[0058] Then the gNodeB may use the CQI value to choose an appropriate MCS value for the codeword. For example, if the channel conditions are favorable, a higher CQI index may be selected by the UE and fed back to the gNodeB, which will likely lead to a higher MCS index being selected for the codeword by the gNodeB for the PDSCH MIMO transmission. Conversely, if the channel conditions deteriorate and the SINR levels drop, the reported CQI index may be lower, and the gNodeB may likely choose a lower MCSindex for that codeword as well.

[0059] Therefore, if only one codeword is mapped to up to 4 layers, the MCS selection during link adaptation will be the same for all those layers. In a layer imbalance scenario, the throughput performance may be limited by the post equalized SINR of the weakest link, since the higher SINR of the strongest link may not be fully exploited when a common MCS is selected. This may be illustrated by FIG. 1A and FIG. IB.

[0060] FIG. 1A illustrates a schematic graph of link performance in a case with a layer quality imbalance. FIG. 1A specifically illustrates the BLER performance of a rate-0.85 5G- low density parity check (LDPC) code with 16- quadrature amplitude modulation (QAM) in the presence of layer imbalance over an additive white gaussian noise (AWGN) channel (i.e., curve 101), where even bits are transmitted through a high-quality channel with Eb / No+y, and odd bits are transmitted through a low-quality channel with Eb / No- y, with their ratio being 32 (corresponding to 101og(32)= 15 dB imbalance). The horizontal axis is Eb / No in dB. The curve 102 and 103 illustrate the performance when all bits are transmitted through the low-quality and high-quality channels, respectively.

[0061] It can be seen from FIG. 1A that, the performance of the LDPC code in the presence of layer imbalance (curve 101) is significantly closer to the performance when all bits were transmitted through the lower-quality channel (curve 102) than to when all bits were sent through the higher-quality channel (curve 103). In other words, the link adaptation performance is negatively impacted by the SINR of the weakest link.

[0062] The reason may be that even if some of the MIMO layers could provide better performance, they will be transmitted with a common and lower MCS, decided based on the measured SINR of all the layers reported via single CQI feedback. The layer quality imbalance may be exemplified in FIG. IB, which illustrates a schematic graph of different scenarios with increasing post-equalizer layer imbalance between layers. The curves in FIG. IB may be determined based on field measurements of a single-codeword design. The field measurements show that for the single-codeword design, the SINR layer imbalance with 4-layer transmission may reach between 10 and 28 dB.

[0063] In this case, it is proposed in the present disclosure that, instead of having a common MCS for all the layers, having a codeword (with corresponding MCS) mapped to each or some of the layers may benefit the link performance, so as to unlock the truethroughput potential of MIMO transmissions. Alternatively or in addition, having different modulation orders for layers of one codeword could reduce the negative impact of the layer quality imbalance.

[0064] Thus, there is a need for the UE to report a quality indicator of each layer of one codeword to facilitate the gNB to for example, select different MCS values or modulation orders across layers of the codeword.

[0065] In accordance with some example embodiments of the present disclosure, serval solutions are provided for quality indicator feedback. In one solution, a terminal apparatus determines a plurality of quality indicator values corresponding to a plurality of layers. The terminal apparatus further compresses the plurality of quality indicator values based on layer distribution information and an order of the plurality of quality indicator values, and transmits, to a network apparatus, information associated with the compression comprising the plurality of compressed quality indicator values corresponding to the plurality of layers.

[0066] In another solution, a terminal apparatus determines a plurality of quality indicator values corresponding to a plurality of layers; compress the plurality of quality indicator values based on binning of the plurality of quality indicator values; and transmit, to a network apparatus, information associated with the compression comprising at least one of the plurality of compressed quality indicator values corresponding to the plurality of layers.

[0067] With these solutions, the terminal apparatus can report the quality indicator value per layer to the network apparatus, rather than reporting only one quality indicator value, e.g., CQI for all of the layers. Thus, an MCS value may be selected per layer to improve link adaptation. Moreover, the plurality of quality indicator values are compressed such that the signaling overhead is reduced.

[0068] Example embodiments of the present disclosure will be described in detail below with reference to the accompanying drawings.

[0069] Reference is now made to FIG. 2. FIG. 2 shows an example communication environment 200 in which example embodiments of the present disclosure may be implemented. The network communication 200 comprises one or more terminalapparatuses, such as a terminal apparatus 210, and one or more network apparatuses such as a network apparatus 220. As illustrated in FIG. 2, the terminal apparatus 210 may support four layers in MIMO communications and the four layers may be mapped to a single codeword (denoted as CW). The four layers may have different SINR levels. For example, layer 4 illustrated with shading may have the worst SINR level.

[0070] In some example embodiments, a communication direction from the network apparatus 220 to the terminal apparatus 210 is referred to as a downlink (DL), and a communication direction from the terminal apparatus 210 to the network apparatus 220 is referred to as an uplink (UL). In DL, the network apparatus 220 is a transmitting (TX) apparatus (or a transmitter) and the terminal apparatus 210 is a receiving (RX) apparatus (or a receiver). In UL, the terminal apparatus 210 is a TX apparatus (or a transmitter) and the network apparatus 220 is a RX apparatus (or a receiver).

[0071] Communications in the communication environment 200 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, the communication may utilize any proper wireless communication technology, comprising but not limited to: Code Division Multiple Access (CDMA), Frequency Division Multiple Access (FDMA), Time Division Multiple Access (TDMA), Frequency Division Duplex (FDD), Time Division Duplex (TDD), Multiple-Input Multiple-Output (MIMO), Orthogonal Frequency Division Multiple (OFDM), Discrete Fourier Transform spread OFDM (DFT-s-OFDM) and / or any other technologies currently known or to be developed in the future.

[0072] In the following, for the purpose of illustration, some example embodiments may be described with the terminal apparatus 210 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.

[0073] It is to be understood that the number of apparatuses and their connections shownin FIG. 2 are only for the purpose of illustration without suggesting any limitation. Although illustrated as a base station, the network apparatus 220 may be or may be comprised in any other suitable network device. Although illustrated as a UE, the terminal apparatus 210 may be or may be comprised in any other suitable terminal device. Moreover, the communication environment 200 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 200.

[0074] FIG. 3 illustrates a signaling flow of an example process 300 for quality indicator feedback in accordance with some example embodiments of the present disclosure. For the purpose of discussion, the process 300 will be described below with reference to the terminal apparatus 210 and network apparatus 220 in FIG. 2.

[0075] As illustrated in FIG. 3, in the process 300, the terminal apparatus 210 determines 310 a plurality of quality indicator values corresponding to a plurality of layers. In some embodiments, the plurality of quality indicator values may comprise at least one of a CQI value, a SINR value, a post-equalizer SINR value, or layer quality indicator (EQI) value. The EQI may be any suitable channel quality metric per layer, and the scope of the present disclosure is not limited in this regard.

[0076] The terminal apparatus 210 further compresses 312 the plurality of quality indicator values based on layer distribution information and an order of the plurality of quality indicator values. As discussed above, a layer quality imbalance may be present between multiple MIMO layers and cause negative impact to the link adaptation performance. In this disclosure, the term “layer distribution information” may be defined to indicate the layer quality imbalance between multiple layers for any suitable channel quality metric, for example, post-equalizer SINR or CQI.

[0077] The layer distribution information may further indicate a quality imbalance pattern of the plurality of layers. The pattern may refer to a distribution of layer quality values. The layer distribution information may be specific to a radio environment. For example, a plurality of layers mapped to a single codeword may be associated with one or more beams, and the layer quality imbalance may vary depending on the specific radio environment of the UE and the gNB .

[0078] It is recognized in the present disclosure that, field measurements strongly suggest a quality imbalance pattern of layers. FIGS. 4A, 4B and 4C illustrate schematic diagrams of example quality imbalance patterns in accordance with some example embodiments of the present disclosure. The example quality imbalance patterns in FIGS. 4A, 4B and 4B are determined based on field measurements using a dual-polarized beam setup, which means two independent layers can be sent with the same beam because they are made orthogonal through polarization.

[0079] In FIGS. 4 A, 4B and 4C, it is assumed that LI and L2 are sent in one beam and L3 and L4 are sent in another beam. As illustrated in these figures, layers sent from the same beam may experience similar propagation conditions and thus may exhibit a smaller imbalance (e.g., no higher than 12 dB) than the imbalance from sending layers in different beams (which may reach around 24 dB). For example, LI and L2 may have similar SINR values, L3 and L4 may have similar SINR values, but LI and L3 may have quite different SINR values. As illustrated in FIG. 4B, the imbalance between L2 and L3 may be mainly affected by the pathloss difference between the beam for LI and L2 and the beam for L3 and L4.

[0080] It will be appreciated that these quality imbalance patterns are illustrated only for examples. The layer distribution information may be a-priori layer distribution knowledge determined by UE(s) based on a plurality of past field measurements and may indicate any suitable quality imbalance pattern.

[0081] Based on the layer distribution information, efficient compression of the plurality of quality indicator values corresponding to the plurality of layer is proposed in the present disclosure. In some embodiments, the terminal apparatus 210 may determine, based on the layer distribution information and the order of the plurality of quality indicator values, a number of bits for compressing a specific quality indicator value of the plurality of quality indicator values. The terminal apparatus 210 may further determine, for the specific quality indicator value, a compressed value by quantizing the specific quality indicator value based on the number of bits. In other words, a specific layer quantization rule Q may be applied to each quality indicator value to obtain the corresponding compressed quality indicator value. Details of the compression will be described with reference to FIGS. 5 A, 5B and 5C in the following specification.

[0082] Then, the terminal apparatus 210 transmits 314, to the network apparatus 220, information associated with the compression comprising the plurality of compressed quality indicator values corresponding to the plurality of layers. At network side, the network apparatus 220 receives 316 the information associated with the compression and decompresses 318, based on the information associated with the compression, the plurality of compressed quality indicator values to determine a plurality of quality indicator values corresponding to the plurality of layers. In this way, per-layer quality indicator feedback may be achieved. Moreover, with the compressed quality indicator values, the signaling overhead can be reduced.

[0083] In some embodiments, the terminal apparatus 210 may compress the plurality of quality indicator values by determining a set of numbers of bits based on a number of the plurality of layers and the layer distribution information; and determining, from the set of numbers of bits, a specific number of bits for compressing a specific quality indicator value based on the order of the plurality of quality indicator values.

[0084] The set of numbers of bits may refer to a set of different bit lengths. For example, the bit length may be four bits, three bits, two bits, and one bit. It is worth mentioning that the number of bits may be chosen for each layer to maintain a reasonable granularity. For example, a 4-bit quantization may be selected for the absolute SINR span in the CQI reporting to achieve a quantization step size, in the case of 48 dB, 48 / 16 = 3dB.

[0085] The set of numbers of bits may vary depending on the a-priori layer distribution information and the number of plurality of layers. For example, 9 bits may be used for a 3-layer case and 11 bits may be used for a 4-layer case. The terminal apparatus 210 may select an appropriate bit-length from the set to compress, i.e., quantize a corresponding quality indicator value based on the order of the plurality of quality indicator values and the layer distribution information.

[0086] In some embodiments, the largest quality indicator value in each beam (e.g., LI value and L3 value) may be used as a reference and may be compressed with a larger number of bits, and a further quality indicator value in the respective beam (e.g., L2 value or L4 value) may be compressed by quantizing a difference to the reference value with a smaller number of bits. In this way, a small number of total bits may be required to keep the same quantization granularity.

[0087] FIGS. 5A, 5B and 5C illustrate example sets of numbers of bits for compressing the quality indicator values in accordance with some example embodiments of the present disclosure. As illustrated in FIG. 5A, in a two-layer case, the set of numbers of bits may be (4, 2), which means 4-bits may be used for compressing a first quality indicator value (i.e. LI value), and 2-bits may be used for compressing a second quality indicator value (i.e. L2 value). As discussed with reference to FIG. 4A, the LI and L2 may have similar quality values, i.e., a difference between LI and L2 is small, such that two bits may be enough to quantize the difference in a reasonable granularity. Thus, LI value may be quantized with 4 bits, which may cover a total absolute span of 48dB. L2 value may be compressed by quantizing a difference relative to LI value with 2 bits, which may cover a span of 12dB below the LI value.

[0088] As illustrated in FIG. 5B, in a three-layer case, the set of numbers of bits may be (4, 2, 3), which means 4-bits may be used for compressing a first quality indicator value (i.e. LI value), 2-bits may be used for compressing a second quality indicator value (i.e. L2 value), and 3-bits may be used for compressing a third quality indicator value (i.e. L3 value). As discussed with reference to FIG. 4B, LI and L3 may have quite different values, such that a larger number of bits (e.g., 3 bits covering a span of 24dB) may be required to compress the L3 value. Particularly, L3 value may be compressed by quantizing a difference relate to a value associated with the LI value. The value associated with the LI value may be determined based on a predetermined maximum difference value (also referred to as maximum delta) associated with the layer distribution information. For example, the layer distribution information may indicate a predetermined difference between layer qualities of two beams.

[0089] As illustrated in FIG. 5C, in a four-layer case, the set of numbers of bits may be (4, 2, 3, 2), which means 4-bits may be used for compressing a first quality indicator value (i.e. LI value), 2-bits may be used for compressing a second quality indicator value (i.e. L2 value), 3-bits may be used for compressing a third quality indicator value (i.e. L3 value), and 2-bits may be used for compressing a fourth quality indicator value (i.e. L4 value). As discussed with reference to FIG. 4C, L3 and L4 may have similar quality indicator values, such that two bits may be enough to compress the L4 value by quantizing a difference to L3 value in a reasonable granularity. In the example of FIG. 5C, 4+2+3+2 = 1 1 bits may be required in total, which is smaller than 16 bits used in a baseline casewhere 4 bits are required for each layer.

[0090] It will be appreciated that example numbers of bits in FIGS. 5 A, 5B and 5C are illustrated only for exemplary purposes without suggesting any limitation. Without loss of generality, several embodiments are described below with similar principles to the examples in FIGS. 5A, 5B and 5C. Repetitive description is omitted herein for simplicity.

[0091] In some embodiments, in accordance with a determination that a first quality indicator value is the largest value in the plurality of quality indicator values, the terminal apparatus 210 may determine, from the set of numbers of bits, a first number of bits for quantizing the first quality indicator value; and determine, from the set of numbers of bits, a second number of bits for quantizing a second quality indicator value of the plurality of quality indicator values, the second number of bits being smaller than the first number of bits. In some embodiments, the terminal apparatus 210 may determine the compressed second quality indicator value by quantizing a difference between the second quality indicator value and the first quality indicator value based on the second number of bits.

[0092] The embodiments may apply to any suitable case with two or more layers. In this way, the largest quality indicator value may be quantized with the largest number of bits and a smaller value may be compressed by quantizing a difference to the largest value with a smaller number of bits. Thus, a total number of bits for indicating the quality indicator values may be limited.

[0093] In some embodiments, the terminal apparatus 210 may determine, from the set of numbers of bits, a third number of bits for quantizing a third quality indicator value of the plurality of quality indicator values; and determine the compressed third quality indicator value by quantizing a difference between the third quality indicator value and a value associated with the first quality indicator value based on the third number of bits, wherein the value associated with the first quality indicator value is determined based on a predetermined maximum difference value associated with the layer distribution information.

[0094] The embodiments may apply to any suitable case with three or more layers. In this way, a quality indicator value with a relatively large difference to a reference quality indicator value (e.g., LI value) may be compressed by quantizing a difference to a maximum delta of the reference quality indicator value. Thus, a total number of bits forindicating the quality indicator values may be limited.

[0095] In some embodiments, determining the number of bits for compressing the quality indicator value based on the order of the plurality of quality indicator values further comprises: determining a fourth number of bits for quantizing a fourth quality indicator value of the plurality of quality indicator values; and determining the compressed fourth quality indicator value by quantizing a difference between the fourth quality indicator value and the third quality indicator value. The embodiments may apply to any suitable case with four or more layers. In this way, a total number of bits for indicating the quality indicator values may be limited.

[0096] In some embodiments, the third number of bits is larger than at least one of the second number of bits or the fourth number of bits. For example, in FIG. 5C, the third number of bits for compressing L3 value (i.e., 3 bits) is larger than the second number of bits for compressing L2 value (i.e., 2 bits) and the fourth number of bits for compressing L4 value (i.e., 2 bits).

[0097] In the following, example signaling flows for transmitting the compressed quality indicator values will be discussed.

[0098] In some embodiments, the terminal apparatus 210 may determine a compressed quality report parameter including a plurality of bits indicating the plurality of compressed quality indicator values corresponding to the plurality of layers. In this disclosure, a new CSI report quantity or parameter may be defined to indicate the compressed quality report parameter. For the purpose of discussion, the compressed quality report parameter may be referred to as compressed layer quality indicator (CLQI) in the following.

[0099] In some embodiments, the terminal apparatus 210 may transmit the compressed quality report parameter, i.e., CLQI in a CSI report, as a part of the information associated with the compression. In some embodiments, the information associated with the compression may further comprise a first indication of a format of the compressed quality report parameter. The indication of the format of the compressed quality report parameter may indicate the set of numbers of bits comprised in the compressed quality report parameter. Alternatively or additionally, the indication of format may indicate a total number of bits comprised in the compressed quality report parameter. The indication offormat may be also referred to as CLQI quantization. Example CLQI formats for different numbers of layers are shown below in Table 1.Table 1. Example CLQI formats for different numbers of layers

[0100] In some embodiments, the terminal apparatus 210 may transmit the CLQI in the CSI report along with the CRI, RI and PMI. As seen in Error! Reference source not found, the CLQI could occupy between 4 and 11 bits depending on the number of layers (i.e., the rank, denoted as v).

[0101] In some embodiments, the terminal apparatus 210 may transmit the CLQI quantization in a medium access control (MAC) control element (CE) message. The terminal apparatus 210 may transmit the CLQI quantization with a lower periodicity than the CLQI. This is because the field measurements indicate that the ordering and layer imbalance may not change that rapidly when compared to the periodicity of CSI reporting. Thus the information on CLQI quantization may be communicated less often in a new “CLQI quantization” MAC CE message sent from the UE to the gNB.

[0102] In some embodiments, the information associated with the compression may further comprise a second indication of an order of the plurality of layers corresponding to the plurality of quality indicator values. The second indication may be also referred to as layer sorting information (LSI). The LSI may be used by the network apparatus 220 to map a specific number of bits in the CLQI to a specific layer. The LQI may occupy between log2(2!) = 1 bits and [Iog2(4!)]= 5 bits, as exemplified in FIG. 6.

[0103] FIG. 6 illustrates example LSI for different numbers of layers in accordance with some example embodiments of the present disclosure. Specifically, FIG. 6 illustratesexample LSI 610 for a 2-layer case, example LSI 620 for a 3-layer case and example LSI 630 for a 4-layer case.

[0104] The terminal apparatus 210 may transmit the LSI with a lower periodicity than the CLQI. The terminal apparatus 210 may transmit the LSI in a CSI report comprising the plurality of compressed quality indicator values. That is, the LSI may be sent as a part of the regular CSI reporting along with the CRI, RI, PMI and CLQI. Alternatively or additionally, the terminal apparatus 210 may transmit the LSI in a MAC CE message. For example, a layer sorting report MAC CE may be sent by the UE.

[0105] In some embodiments, the terminal apparatus 210 may transmit the LSI in the CSI report based on receiving an activation of layer sorting. For example, a MAC CE message indicating LSI report deactivation or activation may be sent by the gNB, and the LSI may be omitted or included in the CSI report based on the received deactivation or activation. This indication of deactivation or activation may only occupy 1 bit, with 1 indicating the activation and 0 indicating the deactivation.

[0106] In some embodiments, the terminal apparatus 210 may transmit, to the network apparatus 220, capability information of per-layer quality reporting. In some embodiments, the terminal apparatus 210 may receive, from the network apparatus 220, a configuration for per-layer quality reporting. For example, the configuration for per- layer quality reporting may indicate the activation of LSI reporting.

[0107] At network side, based on received CLQI, the network apparatus 220 may determine, from the plurality of bits included in the CLQI, a plurality of subsets of bits corresponding to the plurality of layers; and determine, based on the plurality of subsets of bits, the plurality of quality indicator values corresponding to the plurality of layers. The network apparatus 220 may divide, based on the CLQI quantization, the plurality of bits into the plurality of subsets of bits corresponding to the plurality of layers. Then, the network apparatus 220 may map, based on the LSI, a specific subset of bits of the plurality of subsets of bits to a quality indicator value corresponding to a specific layer of the plurality of layers.

[0108] After decompressing the compressed quality indicator values corresponding the plurality of layers, the network apparatus 220 may use the quality indicator value per- layer to perform link adaptation, including e.g., selecting a precoder, and / or one or morelayers for transmission. That is, the network apparatus 220 may decide on how to adapt transmission, by selecting the number of layers, the best precoder and the best MCS for each layer, which can be, for example, pre-defined via optimized tables. In some embodiments, the network apparatus 220 may determine, based on the plurality of quality indicator values, one or more MCS indices and / or one or more modulation orders for the plurality of layers. For example, the network apparatus 220 may select a MCS index and / or a modulation order for each layer of the plurality of layers to reduce the negative impact of the layer quality imbalance.

[0109] FIG. 7 illustrates a signaling flow of an example process 700 for CSI signaling in accordance with some example embodiments of the present disclosure. As illustrated in FIG. 7, the process 700 involves a UE 710 and a gNodeB 720. The UE 710 may be an example of the terminal apparatus 210 in FIG. 2 and the gNodeB 720 may be an example of the network apparatus 220 in FIG. 2. The process 700 may be deemed as a detailed example of the process 300 in FIG. 3.

[0110] In the process 700, at Step 1, the UE 710 has established a radio resource control (RRC) connection with the gNodeB 720. At Step 2, upon the request of the gNodeB 720, the UE 710 sends an RRC message reporting its capabilities, such as supported bandwidth, subcarrier spacing, modulation schemes, MIMO layers and so on. This capability message may also include the information on the UE capability of per-layer quality reporting. At Step 3, the UE 710 shares its capability information which includes the capability of per- layer quality reporting.

[0111] At Step 4, the gNodeB 720 informs, via RRC signaling, the UE 710 of a CSI resource configuration for DL CSI signaling (e.g., ZP CSI-RS, NZP CSI-RS, interference measurement (IM) CSI-RS) for subsequent channel measurement.

[0112] At Step 5, the gNodeB 720 informs, via RRC signaling, the UE 710 of a CSI report configuration, including the settings chosen for CSI reporting, such as codebook configuration, frequency granularity for CQI and PMI, measurement restrictions and which CSI parameters (reporting quantities) to report. The CSI report configuration also requests for a new reporting quantity that includes per layer quality information. As discussed above, the new reporting quantity may be cri-RI-PMI-CLQI-LSI or cri-RI-PMI- CLQI.

[0113] At Step 6, the gNodeB 720 transmits DL reference signals to the UE 710 (e.g., NZP CSI-RS). At Step 7, the UE 710 performs CSI acquisition. Specially, at Step 7.1 the UE 710 select the CRI, v and PMI. At Step 7.2, the UE 710 obtains LQI per layer, e.g., LQIi, ..., LQL- At Step 7.3, the UE 710 sorts LQIs in increasing order to obtain LSI. At Step 7.4, the UE 710 employs the above compression solution for compressing the LQI per layer to obtain the CLQI per layer. Specially, at Step 7.4.1, the UE 710 applies layer quantization rule Q to each LQI value. At Step 7.4.2, the UE 710 obtains CLQI per layer, e.g.,CLQIv= { Q .LQI ... QCLQIV-)}.

[0114] At Step 8, the UE 710 reports this CLQI per layer along with the remaining CSI parameters configured to be reported. In some examples, the UE 710 performs 731 CSI reporting by reporting the CRI, RI, PMI and CLQI in a CSI report. The UE 710 further reports the CLQI quantization in a MAC CE message and reports LSI in a MAC CE message. Alternatively, the UE 710 performs 732 CSI reporting by reporting the CRI, RI, PMI, CLQI and LSI in a CSI report based on the activation of layer sorting. The activation of layer sorting is transmitted from the gNodeB in an LSI MAC CE message. The UE 710 further reports the CLQI quantization in a MAC CE message.

[0115] At Step 9, the gNodeB 720 uses the received information to perform link adaptation, for example, MCS selection only. Specifically, at Step 9.1, the gNodeB 720 recovers the LQI per layer using the CLQI quantization information (i.e., CLQI and CLQI quantization) and the LSI. At Step 9.2, the gNodeB 720 maps each LQI to an MCS table entry, i.e., select an MCS index for each layer.

[0116] At Step 10, the gNodeB 720 informs the UE 710 on decisions such as the number of transmitted layers, layer to codeword mapping, and MCS through the DCI, carried by physical downlink control channel (PDCCH), so that the UE 710 can properly decode the received signal. At Step 11, the gNodeB 720 transmits physical downlink shared channel (PDSCH) data to the UE 710 using the transmission parameters determined at Step 9.

[0117] FIG. 8 illustrates a signaling flow of another example process 800 for quality indicator feedback in accordance with some example embodiments of the present disclosure. For the purpose of discussion, the process 800 will be described below with reference to the terminal apparatus 210 and network apparatus 220 in FIG. 2.

[0118] As illustrated in FIG. 8, in the process 800, the terminal apparatus 210 determines810 a plurality of quality indicator values corresponding to a plurality of layers. The terminal apparatus 210 further compresses 812 the plurality of quality indicator values based on binning of the plurality of quality indicator values; and transmits 814, to the network apparatus 220, information associated with the compression comprising at least one of the plurality of compressed quality indicator values corresponding to the plurality of layers.

[0119] At network side, the network apparatus 220 receives 816 the information associated with the compression. In some embodiments, the network apparatus 220 may receive the compressed quality report parameter, i.e., CLQI, including a plurality of bits indicating the at least one of the plurality of compressed quality indicator values corresponding to the plurality of layers.

[0120] The network apparatus 220 decompresses 818, based on the information associated with the compression, the plurality of compressed quality indicator values to determine a plurality of quality indicator values corresponding to the plurality of layers. In this way, per-layer quality indicator feedback may be achieved. Moreover, with the compressed quality indicator values, the signaling overhead can be reduced.

[0121] Note that, the process 800 shares some similar steps with the process 300 in FIG. 3. For the purpose of simplicity, detailed description of similar steps is omitted in this specification.

[0122] In the process 800, compared to the process 300, the terminal apparatus 210 employs a different way of compressing the quality indicator values, i.e., compressing the quality indicator values based on the binning of the quality indicator values. Details of the binning of the quality indicator values will be described below.

[0123] In some embodiments, the terminal apparatus 210 may determine, from a plurality of bins in a reference range (also referred to as reference interval), a bin containing a quality indicator value of the plurality of quality indicator values; and determine the compressed quality indicator value by quantizing the quality indicator value based on an index corresponding to the bin of the plurality of bins.

[0124] In other words, a bin (also referred to as interval or quantization level) containing a specific quality indicator value may be identified and the index of the bin may be usedto indicate the compressed quality indicator value, such that the compression of the specific quality indicator value is achieved.

[0125] In some embodiments, the terminal apparatus 210 may determine a reference value for the plurality of quality indicator values; and divide the reference range into the plurality of bins based on the reference value and a number of the plurality of bins.

[0126] At network side, the network apparatus 220 may determine, from the plurality of bits included in the compressed quality report parameter, i.e., CLQI, index vectors of a plurality of indices corresponding to a plurality of bins; and determine, based on the plurality of indices, the plurality of quality indicator values. The network apparatus 220 may determine, for a specific layer of the plurality of layers, a quantized value for the layer based on an index corresponding the layer of the plurality of indices; and determine, based on the quantized value and a reference value, a quality indictor value corresponding to the layer.

[0127] In some embodiments, the reference value may be a statistic value of the plurality of quality indicator values, or a quality indicator value of the plurality of quality indicator values. For example, the reference value may be a mean value, a median value, maximum value, minimum value of the plurality of quality indicator values. As another example, the reference value may be a quality indicator value closer to the mean value, median value, maximum value, minimum value, or the like.

[0128] In some examples, the reference range may be denoted as [M — B', M + B'], as referred to as a typical set. M represents the mean value over the plurality of quality indicator values, e.g., LQI^ ... , LQlv. The value of B' may be an agreement between gNodeB and UE and it may be an indicator of maximum expected layer imbalance. The span of [2B'] for the reference range may be determined based on the span of [min { LQI- , ... ,LQIV}, max{ LQIlt... , LQIV}]. The span of [min { LQIlt... , LQIV}, max{L<2 / i, ..., LQIV}] may be limited since too weak layer (as compared to the best layer) may be not very useful (thus can be dropped or reported with very coarse granularity).

[0129] In some examples, a uniform quantizer with an odd number of T levels (i.e., the number of bins) may be considered within the interval [M — B' , M + B'] . Thus, the quantization step i

[0130] FIG. 9 illustrates a schematic diagram of an example of binning of a reference range in accordance with some example embodiments of the present disclosure. As illustrated in FIG. 9, the reference range may contain seven bins, and quality indicator values LQi, LQ2, LQ3 and LQ4 may be in different bins.

[0131] In some embodiments, index vectors of a plurality of indices corresponding to the plurality of bins may contain a same number of bits. For example, in the example of FIG. 9, the quantized value may be computed as mi = Quantized(LQIi — Mf for i G {1, ..., v} based on the mean value. The respective differences of the quality indicator values to the mean value M are similar, such that the same number of bits may be used as the index vectors of the indices corresponding to the bins. For example, each index vector may contain 2 bits to represent a corresponding index of the bin. The index may be used by the network apparatus 220 to determine the quantization based on the quantization step and hence to recover the quality indicator value.

[0132] At network side, the network apparatus 220 may determine a reference quantization step size of the plurality of bins; and determine the quantized value based on the reference quantization step size and the index. The network apparatus 220 may determine the reference quantization step size based on the reference range for the plurality of quality indicator values and the number of the plurality of bins.

[0133] In the case where the mean value is used, the network apparatus 220 may determine one of the plurality of quality indicator values based on a further quality indicator value of the plurality of quality indicator value and the mean value. For example, the gNodeB may estimate mvfollowing mv« M X v — mt— ••• — mv_j. For example, when v = 4, 2B' = 12, and I = 7, the overhead is 13 bits and the quantization step is 1.71 dB.

[0134] Similarly, in the signaling aspect, the compressed quality indicator parameter, i.e., CLQI may be used to indicate the index vectors of the plurality of compressed quality indicator values. In some embodiments, if the mean value is used, the terminal apparatus 210 may further transmit the mean value as part of the information associated with the compression, and transmit only a subset of the plurality of compressed quality indicator values. In some embodiments, the mean value may be transmitted in the CLQI. Alternatively or additionally, the mean value may be transmitted in a MAC CE message.Example CLQI formats for different numbers of layers are shown below in Table 2, Table 3 and Table 4.Table 2. Example CLQI formats for different numbers of layers

[0135] As illustrated in Table 2, the CLQI may consist of M with 4 bits, and nt!, ..., !!!,,-! via [(v — 1) log2T] bits. The CLQI may be reported in the CSI report along with the CRI, RI and PMI.Table 3. Example CLQI formats for different numbers of layers

[0136] As illustrated in Table 3, the CLQI may not consist of the mean value M. The CLQI may be reported in the CSI report along with CRI, RI and PMI. The mean value M may be transmitted in a MAC CE message as part of quantization information.

[0137] The quantization information may further comprise the reference range, indicated by B' , and the number of bins T. B' and T may be communicated less often through a new “CLQI quantization” MAC CE message sent from the UE to the gNodeB. In some examples, a few combinations of these two values (S', T) may be agreed upon in the specifications and expressed in 2 bits (considering there are, for example, 4 possibilities for = {(5,3), (6,5), (7,7), (8,9)}). In some embodiments, B' and T may be fixed and defined a-priori in the gNodeB and UE side. In some embodiments, the reference range, indicated by B', and the number of bins T may be transmitted in the CLQI, as illustrated in Table 4.Table 4. Example CLQI formats for different numbers of layers

[0138] In some embodiments, index vectors of at least two indices of a plurality of indices corresponding to the plurality of bins may contain different numbers of bits. That is, at least two bins may have bin identifiers with different lengths. In some embodiments, the at least two indices may comprise a first index corresponding to a bin containing the reference value and a second index corresponding to a bin not containing the reference value, and a first index vector of the first index contains less bits than a second index vector of the second index.

[0139] In other words, in some embodiments two bins may correspond to index vectors containing different numbers of bits. For example, the reference value and values closer to the reference value in the same bin may be quantized with more bits (i.e., have a longer bin identifier) whereas values far away from the reference value (i.e., these values and the reference value may be in different bins) may be quantized with less bits (i.e., have a shorter bin identifier) because these values appear less often, such that variable-length indices can be achieved to limit the total number of bits for indicating the compressed quality indicator values. That is, using a variable-length quantizer can assign shorter identifiers to more frequent patterns, thereby reducing the average overhead.

[0140] FIG. 10 illustrates schematic diagrams of other examples of binning of a reference range in accordance with some example embodiments of the present disclosure. As illustrated in FIG. 10, the reference range may contain three bins, and a quality indicator value closer to the statistic value is considered as the reference value, denoted as LQe.

[0141] In the example binning graph 1001, the highest / maximum value EQi is chosen as the statistic value and the reference value LQre. Each value contained in the same bin as the reference value LQref may be quantized as the index of “0”, each value containedin a bin below the reference value LQref may be quantized as the index “10”, each value contained in a bin which is two-level below the reference value LQref may be quantized as the index “11” .

[0142] Similarly, in the example binning graph 1002, the second highest / maximum value LQ2 or the value LQ2 closest to the median is chosen as the statistic value and the reference value LQref. Each value contained in the same bin as the reference value LQref may be quantized as the index of “0”, each value contained in a bin below the reference value LQref may be quantized as the index “10”, each value contained in a bin above the reference value LQref may be quantized as the index “11” .

[0143] Similarly, in the example binning graph 1003, the last value LQ4 is chosen as the statistic value and the reference value LQref. Each value contained in the same bin as the reference value LQref may be quantized as the index of “0”, each value contained in a bin which is one-level higher than the reference value LQref may be quantized as the index “11”, each value contained in a bin which is two-level higher than the reference value LQref may be quantized as the index “10” .

[0144] In some embodiments, index vectors of the plurality of indices may be associated with a number of the plurality of bins. The indices may be associated with some pre-fix free coding, where no index is a prefix of another index. This feature allows to have variable-length indexing, because it is possible to decode the indexing without knowing the length. For example, when T =3. when reading 011100, the gNodeB may know they correspond to 0, 11, 10, 0, because 0 cannot be followed by another bit(s) to form an index and it needs to be interpreted alone. For example, for the variable-length index vectors, a cyclic shift of the index vectors may be applied to create a new correspondence between the index vectors and the quantization bins. Some exemplary CLQI index vectors for the number of bins £-3, 4, 5, 7 are listed below for illustration purposes.CLQI index vectors for T=3: 0, 10, 11CLQI index vectors for =4: 00, 01, 10,11CLQI index vectors for T=5: 00, 01, 10, 110, 111CLQI index vectors for T=7: 00, 010, Oi l, 100, 101, 110, 111

[0145] Example CLQI formats for different numbers of layers are shown below in Table 5.Table 5. Example CLQI formats for different numbers of layers

[0146] In some embodiments, similarly, choices of B' and the number of bins T may be limited to some finite number of combinations, and the index of such choice could be communicated less often through a new “CLQI quantization” MAC CE message to the gNodeB.

[0147] The signaling flows for transmitting the compressed quality indicator values may be similar to those signaling flows as discussed above. In some embodiments, the terminal apparatus 210 may transmit the CLQI in a CSI report. In some embodiments, the terminal apparatus 210 may further transmit quantization information as part of the information associated with the compression. The quantization information may comprise at least one of: the reference value, the reference range, a number of the plurality of bins, an indication of a combination of the reference range and a number of the plurality of bins, a reference quantization step size of the plurality of bins, an indication of a combination of the reference quantization step size and the number of plurality of bins, or a format of the compressed quality report parameter.

[0148] In some embodiments, the plurality of bins may have a uniform quantization step size or non-uniform quantization step sizes, and the reference quantization step size may be uniform quantization step size or a reference step size of the non-uniform quantization step sizes. Depending on the span of the LQIs, LQI4, ..., LQIV, appropriate combinations of quantization step size A and the number of bins T, denoted as (A, T), may be selected for indicating a reporting range. Such a choice may be a part of the quantizationinformation and communicated less often through a new “CLQI quantization” MAC CE message sent from the UE to the gNodeB.

[0149] In a case where reporting range =A::T for uniform quantization, 2 bits may be used to indicate the number of bins T and 1 bit may be used for indicating the quantization step size A. See Error! Reference source not found.Error! Reference source not found, below for more details.Table 6. Example reporting ranges for different numbers of layers

[0150] Table 6 illustrates an example of mapping between quantization step size A (3dB as default, 6dB as an alternative, thus requiring 1 bit) and the number of bins T (showing four different choices, thus requiring 2 bits). The corresponding reporting range is A * T. The choice of quantization steps may be expanded beyond the 3dB choice as shown in the embodiment.

[0151] In some embodiments, non-uniform quantization step sizes may be applied. For example, the quantization step size may be as a function of distance from reference. For illustration purpose, the quantization step size of the zth bin may be set as A; = A +(i — 1), for i = 1,The corresponding reporting range is therefore J^ Aj = A * T + T * (T — l) / 2, as shown in Error! Reference source not found.Table 7. Example reporting ranges for different numbers of layers

[0152] Table 7 illustrates an example of non-uniform mapping between the quantizationstep size A (3dB as default, 6dB as an alternative) and the number of bins £ (showing four different choices). The corresponding reporting range for non-uniform quantization bins

[0153] In some embodiments, the terminal apparatus 210 may transmit the quantization information with a lower periodicity than the compressed quality report parameter. In some embodiments, the terminal apparatus 210 may transmit the quantization information in a MAC CE message. In some embodiments, at least one of the reference value, the reference range, or a number of the plurality of bins is indicated by the plurality of bits included in the CLQI. It will be appreciated that various implementations of the signaling of the CLQI and quantization information may be suitable. Repetitive description is omitted for the purpose of simplicity.

[0154] In some embodiments, the association between the variable length indices and the quantization bins may be unique for each combination of (A, T) or (B’, T) and may be predetermined and agreed by gNodeB and UE.

[0155] In some embodiments, the combination of the reference range and the number of the plurality of bins (B’, T) may be associated with a maximum number of the plurality of bits included in the compressed quality report parameter. For example, for each combination of (B’, T), a lookup table may be defined (deterministic and known to both gNodeB and UE) to indicate the maximum number of bitsused for reporting these CLQI indices. In some examplesmay be set as the mean of required bits, rounded up to the nearest integer, shown in Error! Reference source not found, for reporting CLQI. Examples of the maximum number of bits for CLQI reporting are shown in the following Table 8.Table 8. Examples of the maximum number of bits for CLQI reporting

[0156] In some embodiments, the terminal apparatus 210 may further determine a number of bits needed to indicate the at least one of the plurality of compressed quality indicator values; and decrease, based on a comparison between the needed number of bits and the maximum number of the plurality of bits, the needed number of bits by decreasing the number of the plurality of bins. In other words, for each realization of LQIs {LQI , ..., LQlv} observed / measured by the UE, if the needed number of bits for reporting CLQI index vectors given current choice of (B' , ) is larger than the maximum number of bits N(B',£), the UE could may decrease the needed number of bits by decreasing the number of the plurality of bins.

[0157] In some embodiments, the terminal apparatus 210 may combine, in the plurality of bins, two or more bins into a new bin. For example, the terminal apparatus 210 may combine the lowest two bins (whose index vectors only differ by the last bit) and use the common part of their index vectors as a new index vector for their CLQI reporting. For example, the bin with the index vector of “110” and the bin with the index vector of “111” are now both labeled by “11”, which is not a legitimate index vector.

[0158] Since the gNB will either recover fewer legitimate index vectors (0-11-11-11 to 0-111-111) than expected (PMI has already indicated how many layers) or encounter illegitimate codeword (11-0-10-11 to 110-10-11), gNB will detect this fallback solution and recover the CLQI index vectors successfully. The penalty is increased quantization error for the lowest two bins (weakest channels), which have the least impact to overall throughput. Note that this creates a non-uniform quantization bin, which is different from the case with coarser quantization bins having the uniform step size.

[0159] Alternatively or additionally, the terminal apparatus 210 may increase a quantization step size for at least one of the plurality of bins. For example, the UE may choose a smaller number of quantization levels for reporting. The choice is made such that there is no ambiguity of reporting, or the ambiguity is resolvable following the above solution of combining two or more bins. This will result in less bits but at the cost of increased quantization errors. This may also require an update of T.

[0160] FIG. 11 illustrates a signaling flow of an example process 1100 for CSI signalingin accordance with some example embodiments of the present disclosure. The process 1100 may be deemed as a detailed example of the process 800 in FIG. 8. For the purpose of simplicity, the process 1100 will be described with reference to the process 700 and the UE 710 and gNodeB 720 in FIG. 7. Description of similar steps will be omitted.

[0161] In the process 1100, at Step 5, the gNodeB 720 informs, via RRC signaling, the UE 710 of a CSI report configuration 1110. The CSI report configuration also requests for a new reporting quantity that includes per layer quality information. The new reporting quantity may be cri-RI-PMI-CLQI.

[0162] At Step 7, the UE 710 performs CSI acquisition 1120. Specially, at Step 7.1 the UE 710 select the CRI, v and PMI. At Step 7.2, the UE 710 obtains LQI per layer, e.g., LQIi, ..., LQIV. At Step 7.3, the UE 710 defines uniform or non-uniform quantizer within post-equalizer SINR range with I levels. In other words, the UE 710 defines bins with the uniform quantization step size or non-uniform quantization step sizes in the reference range with the number of bins I. At Step 7.4, the UE 710 employs the above compression solution for compressing the LQI per layer based on binning to obtain the CLQI per layer. Specially, at Step 7.4.1, the UE 710 computes quantized level of each layer’s LQI, i.e., determining a bin containing each layer’s LQI. At Step 7.4.2, the UE 710 obtains CLQI per layer, e.g.,CLQIv= { Q LQI^ ... Q^LQI^}.

[0163] At Step 8, the UE 710 reports this CLQI per layer along with the remaining CSI parameters configured to be reported in a CSI report. The UE 710 may further report the quantization information such as the reference range B' and the number of bins Z in a MAC CE message.

[0164] At Step 9, the gNodeB 720 uses the received information to perform link adaptation, for example, MCS selection only. Specifically, at Step 9.1, the gNodeB 720 recovers the LQI per layer using the CLQI quantization information (i.e., CLQI and quantization information such as B' and Z). At Step 9.2, the gNodeB 720 maps each LQI to an MCS table entry, i.e., select an MCS index for each layer.

[0165] FIG. 12 illustrates schematic diagrams of examples of a CSI report quantity in accordance with some example embodiments of the present disclosure. Corresponding examples of the signaling overhead is shown in Table 9 as below.

[0166] The diagram 1210 illustrates an example CSI report quantity cri-RI-LI-PMI-CQI. This is one of the current CSI reporting quantities supported in 5G NR. It includes CRI, RI, LI, PMI and CQI feedback. Only one CQI value is reported for all layers. This would be considered as a lower bound of CSI overhead, and this method is referred to as the legacy method in Table 9.

[0167] The diagram 1220 illustrates an example CSI report quantity cri-RI-PMI-LQI. This reporting quantity is currently not part of the current standard. It is used as a baseline and an upper bound of CSI overhead, with a straightforward approach of reporting one CQI per layer. The same CRI, RI and PMI feedback would be kept, with a CQI / SINR value per layer reported with LQI. This would be considered as an upper bound of CSI overhead, and this method is referred to as the baseline method in Table 9.

[0168] The diagram 1230 illustrates an example CSI report quantity cri-RI-PMI-CLQI- LSI. This reporting quantity is currently not part of the current standard. This proposed reporting quantity follows the same principle of the baseline but would transmit instead a compressed LQI per layer. This compression would require the gNodeB to be informed of the SINR-based layer sorting (LSI) on the UE side. This method is referred to as method 1.1 in Table 9.

[0169] The diagram 1240 illustrates an example CSI report quantity cri-RI-PMI-CLQI. This reporting quantity is currently not part of the current standard. This new proposed reporting quantity is similar to the one in the diagram 1230, but the compression of the per layer LQI information follows instead the same ordering as dictated by the PMI, to prevent having to report the SINR-based layer sorting. This CSI report quantity may refer to Method 2.1 when a mean value is used for the compression and refer to Method 2.2 when a reference value is used for the compression in Table 9.

[0170] To demonstrate the overhead advantage of the solutions proposed in the present disclosure, a comparison is done among the above CSI reporting quantities under the following assumptions: 1) considering v = 4 and assuming that 2B = 48 dB; 2) since the CRI, RI and PMI overhead is common to all the methods, omitting their overhead contribution and only considering the overhead required to report CLQI reporting and MAC CE CLQI quantization reporting; 3) assuming a periodic CSI report with periodicity T ms (can usually be configured to be between 4 and 640 slots, which for a 30 KHzsubcarrier spacing would be between 0.5 ms and 80 ms); 4) given how short the max CSI periodicity can be, assuming a change in the layer imbalance behavior caused by the environment or the user is not expected more often than every 3xT, as an example; 5) for a v = 4, considering an imbalance between the max and min layer no larger than 2B’ = 10 dB (otherwise the UE would most likely opt for a drop of rank); and 6) assuming T is selected so that the quantization step is similar for all the methods, to rule out any precision concerns.

[0171] Error! Reference source not found, displays the overhead results over a period of 3xT ms. Results show that the UE, under this example, would be able to communicate LQI to the gNodeB with an improved precision when compared to legacy (since it offers a 3dB quantization step per layer, instead of 3dB quantization step for the average of the layers) using considerably less bits (between 27 bits and 40 bits) than the ones required to hit the same precision using the baseline solution.Table 9. Overhead and quantization step comparison

[0172] FIG. 13 shows a flowchart of an example method 1300 implemented at a terminal 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 terminal apparatus 210 in FIG. 2.

[0173] At block 1310, the terminal apparatus 210 determines a plurality of quality indicator values corresponding to a plurality of layers.

[0174] At block 1320, the terminal apparatus 210 compresses the plurality of quality indicator values based on layer distribution information and an order of the plurality of quality indicator values.

[0175] At block 1330, the terminal apparatus 210 transmits, to a network apparatus, information associated with the compression comprising the plurality of compressed quality indicator values corresponding to the plurality of layers.

[0176] In some example embodiments, compressing the plurality of quality indicator values based on the order of the plurality of quality indicator values and the layer distribution information comprises: determining, based on the order and the layerdistribution information, a number of bits for compressing a quality indicator value of the plurality of quality indicator values; and determining the compressed quality indicator value by quantizing the quality indicator value based on the number of bits.

[0177] In some example embodiments, determining, based on the order and the layer distribution information, the number of bits for compressing the quality indicator value of the plurality of quality indicator values comprises: determining, a set of numbers of bits based on a number of the plurality of layers and the layer distribution information; and determining, from the set of numbers of bits, the number of bits for compressing the quality indicator value based on the order of the plurality of quality indicator values.

[0178] In some example embodiments, determining the number of bits for compressing the quality indicator value based on the order of the plurality of quality indicator values comprises: in accordance with a determination that a first quality indicator value is the largest value in the plurality of quality indicator values, determining, from the set of numbers of bits, a first number of bits for quantizing the first quality indicator value; and determining, from the set of numbers of bits, a second number of bits for quantizing a second quality indicator value of the plurality of quality indicator values, the second number of bits being smaller than the first number of bits.

[0179] In some example embodiments, determining the compressed quality indicator value by quantizing the quality indicator value based on the number of bits comprises: determining the compressed second quality indicator value by quantizing a difference between the second quality indicator value and the first quality indicator value based on the second number of bits.

[0180] In some example embodiments, determining the number of bits for compressing the quality indicator value based on the order of the plurality of quality indicator values further comprises: determining, from the set of numbers of bits, a third number of bits for quantizing a third quality indicator value of the plurality of quality indicator values; and determining the compressed third quality indicator value by quantizing a difference between the third quality indicator value and a value associated with the first quality indicator value based on the third number of bits, wherein the value associated with the first quality indicator value is determined based on a predetermined maximum difference value associated with the layer distribution information.

[0181] In some example embodiments, determining the number of bits for compressing the quality indicator value based on the order of the plurality of quality indicator values further comprises: determining a fourth number of bits for quantizing a fourth quality indicator value of the plurality of quality indicator values; and determining the compressed fourth quality indicator value by quantizing a difference between the fourth quality indicator value and the third quality indicator value.

[0182] In some example embodiments, the third number of bits is larger than at least one of the second number of bits or the fourth number of bits.

[0183] In some example embodiments, the method 1300 further comprises: determining a compressed quality report parameter including a plurality of bits indicating the plurality of compressed quality indicator values corresponding to the plurality of layers.

[0184] In some example embodiments, transmitting to the network apparatus the information associated with the compression comprises: transmitting the compressed quality report parameter in a channel state information (CSI) report.

[0185] In some example embodiments, the information associated with the compression further comprises a first indication of a format of the compressed quality report parameter.

[0186] In some example embodiments, transmitting, to the network apparatus, the information associated with the compression comprises transmitting the first indication in a medium access control (MAC) control element (CE) message.

[0187] In some example embodiments, transmitting the first indication comprises: transmitting the first indication with a lower periodicity than the compressed quality report parameter.

[0188] In some example embodiments, the information associated with the compression further comprises a second indication of an order of the plurality of layers corresponding to the plurality of quality indicator values.

[0189] In some example embodiments, transmitting, to the network apparatus, the information associated with the compression comprises transmitting the second indication in at least one of: a CSI report comprising the plurality of compressed quality indicator values, or a medium access control (MAC) control element (CE) message.

[0190] In some example embodiments, transmitting the second indication comprises: transmitting the second indication in the CSI report based on receiving an activation of layer sorting.

[0191] In some example embodiments, transmitting the second indication comprises: transmitting the second indication with a lower periodicity than the compressed quality report parameter.

[0192] In some example embodiments, the method 1300 further comprises: transmitting, to the network apparatus, capability information of per-layer quality reporting.

[0193] In some example embodiments, the method 1300 further comprises: receiving, from the network apparatus, a configuration for per-layer quality reporting.

[0194] In some example embodiments, the layer distribution information is a-priori layer distribution knowledge determined by the terminal apparatus based on a plurality of past field measurements.

[0195] In some example embodiments, the layer distribution information indicates a quality imbalance pattern of layers associated with one or more beams.

[0196] In some example embodiments, the plurality of quality indicator values comprise at least one of a channel quality indicator (CQI) value, post-equalizer signal-to- interference-plus-noise ratio (SINR) value, or layer quality indicator (LQI) value.

[0197] In some example embodiments, a single codeword is mapped to the plurality of layers.

[0198] FIG. 14 shows a flowchart of an example method 1400 implemented at a network apparatus in accordance with some example embodiments of the present disclosure. For the purpose of discussion, the method 1400 will be described from the perspective of the network apparatus 220 in FIG. 2.

[0199] At block 1410, the network apparatus 220 receives, from a terminal apparatus, information associated with compression comprising a plurality of compressed quality indicator values corresponding to a plurality of layers.

[0200] At block 1420, the network apparatus 220 decompresses, based on the information associated with the compression, the plurality of compressed qualityindicator values to determine a plurality of quality indicator values corresponding to the plurality of layers.

[0201] In some example embodiments, receiving from the terminal apparatus the information associated with the compression comprises: receiving a compressed quality report parameter in a channel state information (CSI) report, the compressed quality report parameter including a plurality of bits indicating the plurality of compressed quality indicator values corresponding to the plurality of layers.

[0202] In some example embodiments, decompressing, based on the information associated with the compression, the plurality of compressed quality indicator values to determine the plurality of quality indicator values corresponding to the plurality of layers comprises: determining, from the plurality of bits included in the compressed quality report parameter, a plurality of subsets of bits corresponding to the plurality of layers; and determining, based on the plurality of subsets of bits, the plurality of quality indicator values corresponding to the plurality of layers.

[0203] In some example embodiments, determining, from the plurality of bits included in the compressed quality report parameter, the plurality of subsets of bits corresponding to the plurality of layers comprises: dividing, based on a format of compressed quality report parameter, the plurality of bits into the plurality of subsets of bits corresponding to the plurality of layers.

[0204] In some example embodiments, determining, based on the plurality of subsets of bits, the plurality of quality indicator values corresponding to the plurality of layers comprises: mapping, based on an order of the plurality of layers, a subset of bits of the plurality of subsets of bits to a quality indicator value corresponding to a respective layer of the plurality of layers.

[0205] In some example embodiments, the information associated with the compression further comprises a first indication of the format of the compressed quality report parameter.

[0206] In some example embodiments, receiving, from the terminal apparatus, the information associated with the compression comprises receiving the first indication in a medium access control (MAC) control element (CE) message.

[0207] In some example embodiments, receiving the first indication comprises: receiving the first indication with a lower periodicity than the compressed quality report parameter.

[0208] In some example embodiments, the information associated with the compression further comprises a second indication of the order of the plurality of layers.

[0209] In some example embodiments, receiving, from the terminal apparatus, the information associated with the compression comprises receiving the second indication in at least one of: a CSI report comprising the plurality of compressed quality indicator values, or a medium access control (MAC) control element (CE) message.

[0210] In some example embodiments, receiving the second indication comprises: receiving the second indication with a lower periodicity than the compressed quality report parameter.

[0211] In some example embodiments, the method 1400 further comprises: transmitting, to the terminal apparatus, an activation of layer sorting.

[0212] In some example embodiments, the network apparatus is further caused to determine at least one of the following for the plurality of layers based on the plurality of quality indicator values corresponding to the plurality of layers: one or more modulation and coding scheme (MCS) indices, one or more modulation orders, a selection of one or more layers, or a precoder.

[0213] In some example embodiments, the method 1400 further comprises: receiving, from the terminal apparatus, capability information of per-layer quality reporting.

[0214] In some example embodiments, the method 1400 further comprises: transmitting, to the terminal apparatus, a configuration for per-layer quality reporting.

[0215] In some example embodiments, the plurality of quality indicator values comprise at least one of a channel quality indicator (CQI) value, post-equalizer signal-to- interference-plus-noise ratio (SINR) value, or layer quality indicator (LQI) value.

[0216] In some example embodiments, a single codeword is mapped to the plurality of layers.

[0217] In some example embodiments, a terminal apparatus capable of performing anyof the method 1300 (for example, the terminal apparatus 210 in FIG. 2) 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 terminal apparatus may be implemented as or included in the terminal apparatus 210 in FIG. 2.

[0218] In some example embodiments, the terminal apparatus comprises means for determining a plurality of quality indicator values corresponding to a plurality of layers; means for compressing the plurality of quality indicator values based on layer distribution information and an order of the plurality of quality indicator values; and means for transmitting, to a network apparatus, information associated with the compression comprising the plurality of compressed quality indicator values corresponding to the plurality of layers.

[0219] In some example embodiments, the means for compressing the plurality of quality indicator values based on the order of the plurality of quality indicator values and the layer distribution information comprises: means for determining, based on the order and the layer distribution information, a number of bits for compressing a quality indicator value of the plurality of quality indicator values; and means for determining the compressed quality indicator value by quantizing the quality indicator value based on the number of bits.

[0220] In some example embodiments, the means for determining, based on the order and the layer distribution information, the number of bits for compressing the quality indicator value of the plurality of quality indicator values comprises means for: determining, a set of numbers of bits based on a number of the plurality of layers and the layer distribution information; and means for determining, from the set of numbers of bits, the number of bits for compressing the quality indicator value based on the order of the plurality of quality indicator values.

[0221] In some example embodiments, the means for determining the number of bits for compressing the quality indicator value based on the order of the plurality of quality indicator values comprises: means for in accordance with a determination that a first quality indicator value is the largest value in the plurality of quality indicator values, determining, from the set of numbers of bits, a first number of bits for quantizing the firstquality indicator value; and means for determining, from the set of numbers of bits, a second number of bits for quantizing a second quality indicator value of the plurality of quality indicator values, the second number of bits being smaller than the first number of bits.

[0222] In some example embodiments, the means for determining the compressed quality indicator value by quantizing the quality indicator value based on the number of bits comprises: means for determining the compressed second quality indicator value by quantizing a difference between the second quality indicator value and the first quality indicator value based on the second number of bits.

[0223] In some example embodiments, the means for determining the number of bits for compressing the quality indicator value based on the order of the plurality of quality indicator values further comprises: means for determining, from the set of numbers of bits, a third number of bits for quantizing a third quality indicator value of the plurality of quality indicator values; and means for determining the compressed third quality indicator value by quantizing a difference between the third quality indicator value and a value associated with the first quality indicator value based on the third number of bits, wherein the value associated with the first quality indicator value is determined based on a predetermined maximum difference value associated with the layer distribution information.

[0224] In some example embodiments, the means for determining the number of bits for compressing the quality indicator value based on the order of the plurality of quality indicator values further comprises: means for determining a fourth number of bits for quantizing a fourth quality indicator value of the plurality of quality indicator values; and means for determining the compressed fourth quality indicator value by quantizing a difference between the fourth quality indicator value and the third quality indicator value.

[0225] In some example embodiments, the third number of bits is larger than at least one of the second number of bits or the fourth number of bits.

[0226] In some example embodiments, the terminal apparatus further comprises: means for determining a compressed quality report parameter including a plurality of bits indicating the plurality of compressed quality indicator values corresponding to the plurality of layers.

[0227] In some example embodiments, the means for transmitting to the network apparatus the information associated with the compression comprises: means for transmitting the compressed quality report parameter in a channel state information (CSI) report.

[0228] In some example embodiments, the information associated with the compression further comprises a first indication of a format of the compressed quality report parameter.

[0229] In some example embodiments, the means for transmitting, to the network apparatus, the information associated with the compression comprises means for transmitting the first indication in a medium access control (MAC) control element (CE) message.

[0230] In some example embodiments, the means for transmitting the first indication comprises: means for transmitting the first indication with a lower periodicity than the compressed quality report parameter.

[0231] In some example embodiments, the information associated with the compression further comprises a second indication of an order of the plurality of layers corresponding to the plurality of quality indicator values.

[0232] In some example embodiments, the means for transmitting, to the network apparatus, the information associated with the compression comprises means for transmitting the second indication in at least one of: a CSI report comprising the plurality of compressed quality indicator values, or a medium access control (MAC) control element (CE) message.

[0233] In some example embodiments, the means for transmitting the second indication comprises: means for transmitting the second indication in the CSI report based on receiving an activation of layer sorting.

[0234] In some example embodiments, the means for transmitting the second indication comprises: means for transmitting the second indication with a lower periodicity than the compressed quality report parameter.

[0235] In some example embodiments, the terminal apparatus further comprises: means for transmitting, to the network apparatus, capability information of per-layer quality reporting.

[0236] In some example embodiments, the terminal apparatus further comprises: means for receiving, from the network apparatus, a configuration for per-layer quality reporting.

[0237] In some example embodiments, the layer distribution information is a-priori layer distribution knowledge determined by the terminal apparatus based on a plurality of past field measurements.

[0238] In some example embodiments, the layer distribution information indicates a quality imbalance pattern of layers associated with one or more beams.

[0239] In some example embodiments, the plurality of quality indicator values comprise at least one of a channel quality indicator (CQI) value, post-equalizer signal-to- interference-plus-noise ratio (SINR) value, or layer quality indicator (LQI) value.

[0240] In some example embodiments, a single codeword is mapped to the plurality of layers.

[0241] In some example embodiments, a network apparatus capable of performing any of the method 1400 (for example, the network apparatus 220 in FIG. 2) may comprise means for performing the respective operations of the method 1400. 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 220 in FIG. 2.

[0242] In some example embodiments, the network apparatus comprises means for receiving, from a terminal apparatus, information associated with compression comprising a plurality of compressed quality indicator values corresponding to a plurality of layers; and means for decompressing, based on the information associated with the compression, the plurality of compressed quality indicator values to determine a plurality of quality indicator values corresponding to the plurality of layers.

[0243] In some example embodiments, the means for receiving from the terminal apparatus the information associated with the compression comprises: means for receiving a compressed quality report parameter in a channel state information (CSI) report, the compressed quality report parameter including a plurality of bits indicating the plurality of compressed quality indicator values corresponding to the plurality of layers.

[0244] In some example embodiments, the means for decompressing, based on theinformation associated with the compression, the plurality of compressed quality indicator values to determine the plurality of quality indicator values corresponding to the plurality of layers comprises: means for determining, from the plurality of bits included in the compressed quality report parameter, a plurality of subsets of bits corresponding to the plurality of layers; and means for determining, based on the plurality of subsets of bits, the plurality of quality indicator values corresponding to the plurality of layers.

[0245] In some example embodiments, the means for determining, from the plurality of bits included in the compressed quality report parameter, the plurality of subsets of bits corresponding to the plurality of layers comprises: means for dividing, based on a format of compressed quality report parameter, the plurality of bits into the plurality of subsets of bits corresponding to the plurality of layers.

[0246] In some example embodiments, the means for determining, based on the plurality of subsets of bits, the plurality of quality indicator values corresponding to the plurality of layers comprises: means for mapping, based on an order of the plurality of layers, a subset of bits of the plurality of subsets of bits to a quality indicator value corresponding to a respective layer of the plurality of layers.

[0247] In some example embodiments, the information associated with the compression further comprises a first indication of the format of the compressed quality report parameter.

[0248] In some example embodiments, the means for receiving, from the terminal apparatus, the information associated with the compression comprises means for receiving the first indication in a medium access control (MAC) control element (CE) message.

[0249] In some example embodiments, the means for receiving the first indication comprises: means for receiving the first indication with a lower periodicity than the compressed quality report parameter.

[0250] In some example embodiments, the information associated with the compression further comprises a second indication of the order of the plurality of layers.

[0251] In some example embodiments, the means for receiving, from the terminalapparatus, the information associated with the compression comprises means for receiving the second indication in at least one of: a CSI report comprising the plurality of compressed quality indicator values, or a medium access control (MAC) control element (CE) message.

[0252] In some example embodiments, the means for receiving the second indication comprises: receiving the second indication with a lower periodicity than the compressed quality report parameter.

[0253] In some example embodiments, the network apparatus further comprises: means for transmitting, to the terminal apparatus, an activation of layer sorting.

[0254] In some example embodiments, the network apparatus further comprise means for determining at least one of the following for the plurality of layers based on the plurality of quality indicator values corresponding to the plurality of layers: one or more modulation and coding scheme (MCS) indices, one or more modulation orders, a selection of one or more layers, or a precoder.

[0255] In some example embodiments, the network apparatus further comprises: means for receiving, from the terminal apparatus, capability information of per-layer quality reporting.

[0256] In some example embodiments, the network apparatus further comprises: means for transmitting, to the terminal apparatus, a configuration for per-layer quality reporting.

[0257] In some example embodiments, the plurality of quality indicator values comprise at least one of a channel quality indicator (CQI) value, post-equalizer signal-to- interference-plus-noise ratio (SINR) value, or layer quality indicator (LQI) value.

[0258] In some example embodiments, a single codeword is mapped to the plurality of layers.

[0259] FIG. 15 shows a flowchart of an example method 1500 implemented at a terminal apparatus in accordance with some example embodiments of the present disclosure. For the purpose of discussion, the method 1500 will be described from the perspective of the terminal apparatus 210 in FIG. 2.

[0260] At block 1510, the terminal apparatus 210 determines a plurality of qualityindicator values corresponding to a plurality of layers.

[0261] At block 1520, the terminal apparatus 210 compresses the plurality of quality indicator values based on binning of the plurality of quality indicator values.

[0262] At block 1530, the terminal apparatus 210 transmits, to a network apparatus, information associated with the compression comprising at least one of the plurality of compressed quality indicator values corresponding to the plurality of layers.

[0263] In some example embodiments, compressing the plurality of quality indicator values based on the binning of the plurality of quality indicator values comprises: determining, from a plurality of bins in a reference range, a bin containing a quality indicator value of the plurality of quality indicator values; and determining the compressed quality indicator value by quantizing the quality indicator value based on an index corresponding to the bin of the plurality of bins.

[0264] In some example embodiments, the method 1500 further comprises: determining a reference value for the plurality of quality indicator values; and dividing the reference range into the plurality of bins based on the reference value and a number of the plurality of bins.

[0265] In some example embodiments, the reference value is a statistic value of the plurality of quality indicator values, or a quality indicator value of the plurality of quality indicator values.

[0266] In some example embodiments, index vectors of a plurality of indices corresponding to the plurality of bins contain a same number of bits.

[0267] In some example embodiments, the statistic value is a mean value of the plurality of quality indicator values, and the information associated with the compression comprises a subset of the plurality of compressed quality indicator values.

[0268] In some example embodiments, the information associated with the compression further comprises the mean value.

[0269] In some example embodiments, index vectors of at least two indices of a plurality of indices corresponding to the plurality of bins contain different numbers of bits.

[0270] In some example embodiments, the at least two indices comprise a first indexcorresponding to a bin containing the reference value and a second index corresponding to a bin not containing the reference value, and a first index vector of the first index contains less bits than a second index vector of the second index.

[0271] In some example embodiments, index vectors of the plurality of indices are associated with a number of the plurality of bins.

[0272] In some example embodiments, the method 1500 further comprises: determining a compressed quality report parameter including a plurality of bits indicating the at least one of the plurality of compressed quality indicator values corresponding to the plurality of layers.

[0273] In some example embodiments, transmitting to the network apparatus the information associated with the compression comprises: transmitting the compressed quality report parameter in a channel state information (CSI) report.

[0274] In some example embodiments, the information associated with the compression further comprises quantization information comprising at least one of: the reference value, the reference range, a number of the plurality of bins, an indication of a combination of the reference range and a number of the plurality of bins, a reference quantization step size of the plurality of bins, an indication of a combination of the reference quantization step size and the number of plurality of bins, or a format of the compressed quality report parameter.

[0275] In some example embodiments, transmitting to the network apparatus the information associated with the compression comprises: transmitting the quantization information with a lower periodicity than the compressed quality report parameter.

[0276] In some example embodiments, transmitting the quantization information comprises: transmitting the quantization information in a medium access control (MAC) control element (CE) message.

[0277] In some example embodiments, at least one of the reference value, the reference range, or a number of the plurality of bins is indicated by the plurality of bits included in the compressed quality report parameter.

[0278] In some example embodiments, the combination of the reference range and the number of the plurality of bins is associated with a maximum number of the plurality ofbits included in the compressed quality report parameter.

[0279] In some example embodiments, the method 1500 further comprises: determining a number of bits needed to indicate the at least one of the plurality of compressed quality indicator values; and decreasing, based on a comparison between the needed number of bits and the maximum number of the plurality of bits, the needed number of bits by decreasing the number of the plurality of bins.

[0280] In some example embodiments, decreasing the number of the plurality of bins comprises: combining, in the plurality of bins, two or more bins into a new bin, or increasing a quantization step size for at least one of the plurality of bins.

[0281] In some example embodiments, the plurality of bins have a uniform quantization step size or non-uniform quantization step sizes, and the reference quantization step size is the uniform quantization step size or a reference step size of the non-uniform quantization step sizes.

[0282] In some example embodiments, the plurality of quality indicator values comprise at least one of a channel quality indicator (CQI) value, post-equalizer signal-to- interference-plus-noise ratio (SINR) value, or layer quality indicator (LQI) value.

[0283] In some example embodiments, the method 1500 further comprises: transmitting, to the network apparatus, capability information of per-layer quality reporting.

[0284] In some example embodiments, a single codeword is mapped to the plurality of layers.

[0285] FIG. 16 shows a flowchart of an example method 1600 implemented at a network apparatus in accordance with some example embodiments of the present disclosure. For the purpose of discussion, the method 1600 will be described from the perspective of the network apparatus 220 in FIG. 2.

[0286] At block 1610, the network apparatus 220 receives, from a terminal apparatus, information associated with compression comprising at least one of a plurality of compressed quality indicator values corresponding to a plurality of layers.

[0287] At block 1620, the network apparatus 220 decompresses, based on the information associated with the compression, the plurality of compressed qualityindicator values to determine a plurality of quality indicator values corresponding to the plurality of layers.

[0288] In some example embodiments, receiving from the terminal apparatus the information associated with the compression comprises: receiving a compressed quality report parameter in a channel state information (CSI) report, the compressed quality report parameter including a plurality of bits indicating the at least one of the plurality of compressed quality indicator values corresponding to the plurality of layers.

[0289] In some example embodiments, decompressing, based on the information associated with the compression, the plurality of compressed quality indicator values to determine the plurality of quality indicator values corresponding to the plurality of layers comprises: determining, from the plurality of bits included in the compressed quality report parameter, index vectors of a plurality of indices corresponding to a plurality of bins; and determining, based on the plurality of indices, the plurality of quality indicator values.

[0290] In some example embodiments, determining, based on the plurality of indices, the plurality of quality indicator values corresponding to the plurality of layers comprises: determining, for a layer of the plurality of layers, a quantized value for the layer based on an index corresponding the layer of the plurality of indices; and determining, based on the quantized value and a reference value, a quality indictor value corresponding to the layer.

[0291] In some example embodiments, determining the quantized value for the layer based on the index corresponding the layer of the plurality of indices comprises: determining a reference quantization step size of the plurality of bins; and determining the quantized value based on the reference quantization step size and the index.

[0292] In some example embodiments, the plurality of bins have a uniform quantization step size or non-uniform quantization step sizes, and the reference quantization step size is the uniform quantization step size or a reference step size of the non-uniform quantization step sizes.

[0293] In some example embodiments, the method 1600 further comprises: determining the reference quantization step size based on a reference range for the plurality of qualityindicator values and a number of the plurality of bins.

[0294] In some example embodiments, the reference value is a mean value, and determining, based on the plurality of indices, the plurality of quality indicator values comprises: determining one of the plurality of quality indicator values based on a further quality indicator value of the plurality of quality indicator value and the mean value.

[0295] In some example embodiments, the network apparatus is further caused to determine at least one of the following for the plurality of layers based on the plurality of quality indicator values corresponding to the plurality of layers: one or more modulation and coding scheme (MCS) indices, one or more modulation orders, a selection of one or more layers, or a precoder.

[0296] In some example embodiments, the information associated with the compression further comprises quantization information comprising at least one of: a reference value for the plurality of quality indicator values, a reference range for the plurality of quality indicator values, a number of a plurality of bins, an indication of a combination of the reference range and a number of the plurality of bins, a reference quantization step size of the plurality of bins, an indication of a combination of the reference quantization step size and the number of plurality of bins, or a format of the compressed quality report parameter.

[0297] In some example embodiments, receiving from the terminal apparatus the information associated with the compression comprises receiving the quantization information with a lower periodicity than the compressed quality report parameter.

[0298] In some example embodiments, receiving the quantization information comprises receiving the quantization information in a medium access control (MAC) control element (CE) message.

[0299] In some example embodiments, the method 1600 further comprises: receiving, from the terminal apparatus, capability information of per-layer quality reporting.

[0300] In some example embodiments, the method 1600 further comprises: transmitting, to the terminal apparatus, a request for per-layer quality reporting.

[0301] In some example embodiments, the plurality of quality indicator values comprise at least one of a channel quality indicator (CQI) value, post-equalizer signal-to-interference-plus-noise ratio (SINR) value, or layer quality indicator (LQI) value.

[0302] In some example embodiments, a terminal apparatus capable of performing any of the method 1500 (for example, the terminal apparatus 210 in FIG. 2) may comprise means for performing the respective operations of the method 1500. 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 210 in FIG. 2.

[0303] In some example embodiments, the terminal apparatus comprises means for determining a plurality of quality indicator values corresponding to a plurality of layers; means for compressing the plurality of quality indicator values based on binning of the plurality of quality indicator values; and means for transmitting, to a network apparatus, information associated with the compression comprising at least one of the plurality of compressed quality indicator values corresponding to the plurality of layers.

[0304] In some example embodiments, the means for compressing the plurality of quality indicator values based on the binning of the plurality of quality indicator values comprises: means for determining, from a plurality of bins in a reference range, a bin containing a quality indicator value of the plurality of quality indicator values; and means for determining the compressed quality indicator value by quantizing the quality indicator value based on an index corresponding to the bin of the plurality of bins.

[0305] In some example embodiments, the terminal apparatus further comprises: means for determining a reference value for the plurality of quality indicator values; and means for dividing the reference range into the plurality of bins based on the reference value and a number of the plurality of bins.

[0306] In some example embodiments, the reference value is a statistic value of the plurality of quality indicator values, or a quality indicator value of the plurality of quality indicator values.

[0307] In some example embodiments, index vectors of a plurality of indices corresponding to the plurality of bins contain a same number of bits.

[0308] In some example embodiments, the statistic value is a mean value of the plurality of quality indicator values, and the information associated with the compressioncomprises a subset of the plurality of compressed quality indicator values.

[0309] In some example embodiments, the information associated with the compression further comprises the mean value.

[0310] In some example embodiments, index vectors of at least two indices of a plurality of indices corresponding to the plurality of bins contain different numbers of bits.

[0311] In some example embodiments, the at least two indices comprise a first index corresponding to a bin containing the reference value and a second index corresponding to a bin not containing the reference value, and a first index vector of the first index contains less bits than a second index vector of the second index.

[0312] In some example embodiments, index vectors of the plurality of indices are associated with a number of the plurality of bins.

[0313] In some example embodiments, the terminal apparatus further comprises: means for determining a compressed quality report parameter including a plurality of bits indicating the at least one of the plurality of compressed quality indicator values corresponding to the plurality of layers.

[0314] In some example embodiments, the means for transmitting to the network apparatus the information associated with the compression comprises: means for transmitting the compressed quality report parameter in a channel state information (CSI) report.

[0315] In some example embodiments, the information associated with the compression further comprises quantization information comprising at least one of: the reference value, the reference range, a number of the plurality of bins, an indication of a combination of the reference range and a number of the plurality of bins, a reference quantization step size of the plurality of bins, an indication of a combination of the reference quantization step size and the number of plurality of bins, or a format of the compressed quality report parameter.

[0316] In some example embodiments, the means for transmitting to the network apparatus the information associated with the compression comprises: means for transmitting the quantization information with a lower periodicity than the compressed quality report parameter.

[0317] In some example embodiments, the means for transmitting the quantization information comprises: means for transmitting the quantization information in a medium access control (MAC) control element (CE) message.

[0318] In some example embodiments, at least one of the reference value, the reference range, or a number of the plurality of bins is indicated by the plurality of bits included in the compressed quality report parameter.

[0319] In some example embodiments, the combination of the reference range and the number of the plurality of bins is associated with a maximum number of the plurality of bits included in the compressed quality report parameter.

[0320] In some example embodiments, the terminal apparatus further comprises: means for determining a number of bits needed to indicate the at least one of the plurality of compressed quality indicator values; and means for decreasing, based on a comparison between the needed number of bits and the maximum number of the plurality of bits, the needed number of bits by decreasing the number of the plurality of bins.

[0321] In some example embodiments, the means for decreasing the number of the plurality of bins comprises: means for combining, in the plurality of bins, two or more bins into a new bin, or increasing a quantization step size for at least one of the plurality of bins.

[0322] In some example embodiments, the plurality of bins have a uniform quantization step size or non-uniform quantization step sizes, and the reference quantization step size is the uniform quantization step size or a reference step size of the non-uniform quantization step sizes.

[0323] In some example embodiments, the plurality of quality indicator values comprise at least one of a channel quality indicator (CQI) value, post-equalizer signal-to- interference-plus-noise ratio (SINR) value, or layer quality indicator (LQI) value.

[0324] In some example embodiments, the terminal apparatus further comprises: means for transmitting, to the network apparatus, capability information of per-layer quality reporting.

[0325] In some example embodiments, a single codeword is mapped to the plurality of layers.

[0326] In some example embodiments, a network apparatus capable of performing any of the method 1600 (for example, the network apparatus 220 in FIG.2) may comprise means for performing the respective operations of the method 1600. 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 220 in FIG. 2.

[0327] In some example embodiments, the network apparatus comprises means for receiving, from a terminal apparatus, information associated with compression comprising at least one of a plurality of compressed quality indicator values corresponding to a plurality of layers; and means for decompressing, based on the information associated with the compression, the plurality of compressed quality indicator values to determine a plurality of quality indicator values corresponding to the plurality of layers.

[0328] In some example embodiments, the means for receiving from the terminal apparatus the information associated with the compression comprises: means for receiving a compressed quality report parameter in a channel state information (CSI) report, the compressed quality report parameter including a plurality of bits indicating the at least one of the plurality of compressed quality indicator values corresponding to the plurality of layers.

[0329] In some example embodiments, the means for decompressing, based on the information associated with the compression, the plurality of compressed quality indicator values to determine the plurality of quality indicator values corresponding to the plurality of layers comprises: means for determining, from the plurality of bits included in the compressed quality report parameter, index vectors of a plurality of indices corresponding to a plurality of bins; and determining, based on the plurality of indices, the plurality of quality indicator values.

[0330] In some example embodiments, the means for determining, based on the plurality of indices, the plurality of quality indicator values corresponding to the plurality of layers comprises: means for determining, for a layer of the plurality of layers, a quantized value for the layer based on an index corresponding the layer of the plurality of indices; and means for determining, based on the quantized value and a reference value, a qualityindictor value corresponding to the layer.

[0331] In some example embodiments, the means for determining the quantized value for the layer based on the index corresponding the layer of the plurality of indices comprises: means for determining a reference quantization step size of the plurality of bins; and means for determining the quantized value based on the reference quantization step size and the index.

[0332] In some example embodiments, the plurality of bins have a uniform quantization step size or non-uniform quantization step sizes, and the reference quantization step size is the uniform quantization step size or a reference step size of the non-uniform quantization step sizes.

[0333] In some example embodiments, the network apparatus further comprises: means for determining the reference quantization step size based on a reference range for the plurality of quality indicator values and a number of the plurality of bins.

[0334] In some example embodiments, the reference value is a mean value, and determining, based on the plurality of indices, the plurality of quality indicator values comprises: determining one of the plurality of quality indicator values based on a further quality indicator value of the plurality of quality indicator value and the mean value.

[0335] In some example embodiments, the network apparatus further comprises means for determining at least one of the following for the plurality of layers based on the plurality of quality indicator values corresponding to the plurality of layers: one or more modulation and coding scheme (MCS) indices, one or more modulation orders, a selection of one or more layers, or a precoder.

[0336] In some example embodiments, the information associated with the compression further comprises quantization information comprising at least one of: a reference value for the plurality of quality indicator values, a reference range for the plurality of quality indicator values, a number of a plurality of bins, an indication of a combination of the reference range and a number of the plurality of bins, a reference quantization step size of the plurality of bins, an indication of a combination of the reference quantization step size and the number of plurality of bins, or a format of the compressed quality report parameter.

[0337] In some example embodiments, the means for receiving from the terminal apparatus the information associated with the compression comprises means for receiving the quantization information with a lower periodicity than the compressed quality report parameter.

[0338] In some example embodiments, the means for receiving the quantization information comprises means for receiving the quantization information in a medium access control (MAC) control element (CE) message.

[0339] In some example embodiments, the network apparatus further comprises: means for receiving, from the terminal apparatus, capability information of per-layer quality reporting.

[0340] In some example embodiments, the network apparatus further comprises: means for transmitting, to the terminal apparatus, a request for per-layer quality reporting.

[0341] In some example embodiments, the plurality of quality indicator values comprise at least one of a channel quality indicator (CQI) value, post-equalizer signal-to- interference-plus-noise ratio (SINR) value, or layer quality indicator (LQI) value.

[0342] FIG. 17 is a simplified block diagram of a device 1700 that is suitable for implementing example embodiments of the present disclosure. The device 1700 may be provided to implement a communication device, for example, the terminal apparatus 210 or the network apparatus 220 as shown in FIG. 2. As shown, the device 1700 includes one or more processors 1710, one or more memories 1720 coupled to the processor 1710, and one or more communication modules 1740 coupled to the processor 1710.

[0343] The communication module 1740 is for bidirectional communications. The communication module 1740 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 1740 may include at least one antenna.

[0344] The processor 1710 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 processorsbased on multicore processor architecture, as non-limiting examples. The device 1700 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.

[0345] The memory 1720 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) 1724, 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) 1722 and other volatile memories that will not last in the powerdown duration.

[0346] A computer program 1730 includes computer executable instructions that are executed by the associated processor 1710. The instructions of the program 1730 may include instructions for performing operations / acts of some example embodiments of the present disclosure. The program 1730 may be stored in the memory, e.g., the ROM 1724. The processor 1710 may perform any suitable actions and processing by loading the program 1730 into the RAM 1722.

[0347] The example embodiments of the present disclosure may be implemented by means of the program 1730 so that the device 1700 may perform any process of the disclosure as discussed with reference to FIG. 3 to FIG. 16. The example embodiments of the present disclosure may also be implemented by hardware or by a combination of software and hardware.

[0348] In some example embodiments, the program 1730 may be tangibly contained in a computer readable medium which may be included in the device 1700 (such as in the memory 1720) or other storage devices that are accessible by the device 1700. The device 1700 may load the program 1730 from the computer readable medium to the RAM 1722 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).

[0349] FIG. 18 shows an example of the computer readable medium 1800 which may be in form of CD, DVD or other optical storage disk. The computer readable medium 1800 has the program 1730 stored thereon.

[0350] 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.

[0351] Some example embodiments of the present disclosure also provide at least one computer program product tangibly stored on a computer readable medium, such as a non-transitory computer readable medium. The computer program product includes computer-executable instructions, such as those included in program modules, being executed in a device on a target physical or virtual processor, to carry out any of the methods as described above. Generally, program modules include routines, programs, libraries, objects, classes, components, data structures, or the like that perform particular tasks or implement particular abstract data types. The functionality of the program modules may be combined or split between program modules as desired in various embodiments. 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.

[0352] 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, partlyon the machine and partly on a remote machine or entirely on the remote machine or server.

[0353] 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.

[0354] 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.

[0355] Further, although operations are depicted in a particular order, this should not be understood as requiring that such operations be performed in the particular order shown or in sequential order, or that all illustrated operations be performed, to achieve desirable results. In certain circumstances, multitasking and parallel processing may be advantageous. Likewise, although several specific implementation details are contained in the above discussions, these should not be construed as limitations on the scope of the present disclosure, but rather as descriptions of features that may be specific to particular embodiments. Unless explicitly stated, certain features that are described in the context of separate embodiments may also be implemented in combination in a single embodiment. Conversely, unless explicitly stated, various features that are described in the context of a single embodiment may also be implemented in a plurality of embodiments separately or in any suitable sub-combination.

[0356] 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 specificfeatures 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: determine a plurality of quality indicator values corresponding to a plurality of layers; compress the plurality of quality indicator values based on layer distribution information and an order of the plurality of quality indicator values; and transmit, to a network apparatus, information associated with the compression comprising the plurality of compressed quality indicator values corresponding to the plurality of layers.

2. The terminal apparatus of claim 1, wherein compressing the plurality of quality indicator values based on the order of the plurality of quality indicator values and the layer distribution information comprises: determining, based on the order and the layer distribution information, a number of bits for compressing a quality indicator value of the plurality of quality indicator values; and determining the compressed quality indicator value by quantizing the quality indicator value based on the number of bits.

3. The terminal apparatus of claim 2, wherein determining, based on the order and the layer distribution information, the number of bits for compressing the quality indicator value of the plurality of quality indicator values comprises: determining, a set of numbers of bits based on a number of the plurality of layers and the layer distribution information; and determining, from the set of numbers of bits, the number of bits for compressing the quality indicator value based on the order of the plurality of quality indicator values.

4. The terminal apparatus of claim 3, wherein determining the number of bits forcompressing the quality indicator value based on the order of the plurality of quality indicator values comprises: in accordance with a determination that a first quality indicator value is the largest value in the plurality of quality indicator values, determining, from the set of numbers of bits, a first number of bits for quantizing the first quality indicator value; and determining, from the set of numbers of bits, a second number of bits for quantizing a second quality indicator value of the plurality of quality indicator values, the second number of bits being smaller than the first number of bits.

5. The terminal apparatus of claim 4, wherein determining the compressed quality indicator value by quantizing the quality indicator value based on the number of bits comprises: determining the compressed second quality indicator value by quantizing a difference between the second quality indicator value and the first quality indicator value based on the second number of bits.

6. The terminal apparatus of claim 5, wherein determining the number of bits for compressing the quality indicator value based on the order of the plurality of quality indicator values further comprises: determining, from the set of numbers of bits, a third number of bits for quantizing a third quality indicator value of the plurality of quality indicator values; and determining the compressed third quality indicator value by quantizing a difference between the third quality indicator value and a value associated with the first quality indicator value based on the third number of bits, wherein the value associated with the first quality indicator value is determined based on a predetermined maximum difference value associated with the layer distribution information.

7. The terminal apparatus of claim 6, wherein determining the number of bits for compressing the quality indicator value based on the order of the plurality of quality indicator values further comprises: determining a fourth number of bits for quantizing a fourth quality indicator value of the plurality of quality indicator values; anddetermining the compressed fourth quality indicator value by quantizing a difference between the fourth quality indicator value and the third quality indicator value.

8. The terminal apparatus of claim 7, wherein the third number of bits is larger than at least one of the second number of bits or the fourth number of bits.

9. The terminal apparatus of any of claims 1 to 8, wherein the terminal apparatus is further caused to: determine a compressed quality report parameter including a plurality of bits indicating the plurality of compressed quality indicator values corresponding to the plurality of layers.

10. The terminal apparatus of claim 9, wherein transmitting to the network apparatus the information associated with the compression comprises: transmitting the compressed quality report parameter in a channel state information (CSI) report.

11. The terminal apparatus of claim 9 or 10, wherein the information associated with the compression further comprises a first indication of a format of the compressed quality report parameter.

12. The terminal apparatus of claim 11, wherein transmitting, to the network apparatus, the information associated with the compression comprises transmitting the first indication in a medium access control (MAC) control element (CE) message.

13. The terminal apparatus of claim 12, wherein transmitting the first indication comprises: transmitting the first indication with a lower periodicity than the compressed quality report parameter.

14. The terminal apparatus of any of claims 1 to 13, wherein the information associated with the compression further comprises a second indication of an order of the plurality of layers corresponding to the plurality of quality indicator values.

15. The terminal apparatus of claim 14, wherein transmitting, to the network apparatus, the information associated with the compression comprises transmitting the second indication in at least one of: a CSI report comprising the plurality of compressed quality indicator values, or a medium access control (MAC) control element (CE) message.

16. The terminal apparatus of claim 15, wherein transmitting the second indication comprises: transmitting the second indication in the CSI report based on receiving an activation of layer sorting.

17. The terminal apparatus of claim 15, wherein transmitting the second indication comprises: transmitting the second indication with a lower periodicity than the compressed quality report parameter.

18. The terminal apparatus of any of claims 1 to 17, wherein the terminal apparatus is further caused to: transmit, to the network apparatus, capability information of per-layer quality reporting.

19. The terminal apparatus of any of claims 1 to 18, wherein the terminal apparatus is further caused to: receive, from the network apparatus, a configuration for per-layer quality reporting.

20. The terminal apparatus of any of claims 1 to 19, wherein the layer distribution information is a-priori layer distribution knowledge determined by the terminal apparatus based on a plurality of past field measurements.

21. The terminal apparatus of any of claims 1 to 20, wherein the layer distribution information indicates a quality imbalance pattern of layers associated with one or morebeams.

22. The terminal apparatus of any of claims 1 to 21, wherein the plurality of quality indicator values comprise at least one of a channel quality indicator (CQI) value, postequalizer signal-to-interference-plus-noise ratio (SINR) value, or layer quality indicator (LQI) value.

23. The terminal apparatus of any of claims 1 to 22, wherein a single codeword is mapped to the plurality of layers.

24. A network apparatus comprising: 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: receive, from a terminal apparatus, information associated with compression comprising a plurality of compressed quality indicator values corresponding to a plurality of layers; and decompress, based on the information associated with the compression, the plurality of compressed quality indicator values to determine a plurality of quality indicator values corresponding to the plurality of layers.

25. A method comprising: determining, at a terminal apparatus, a plurality of quality indicator values corresponding to a plurality of layers; compressing the plurality of quality indicator values based on layer distribution information and an order of the plurality of quality indicator values; and transmitting, to a network apparatus, information associated with the compression comprising the plurality of compressed quality indicator values corresponding to the plurality of layers.

26. A method comprising: receiving, at a network apparatus and from a terminal apparatus, information associated with compression comprising a plurality of compressed quality indicatorvalues corresponding to a plurality of layers; and decompressing, based on the information associated with the compression, the plurality of compressed quality indicator values to determine a plurality of quality indicator values corresponding to the plurality of layers.

27. A terminal apparatus comprising: means for determining a plurality of quality indicator values corresponding to a plurality of layers; means for compressing the plurality of quality indicator values based on layer distribution information and an order of the plurality of quality indicator values; and means for transmitting, to a network apparatus, information associated with the compression comprising the plurality of compressed quality indicator values corresponding to the plurality of layers.

28. A network apparatus comprising: means for receiving, from a terminal apparatus, information associated with compression comprising a plurality of compressed quality indicator values corresponding to a plurality of layers; and means for decompressing, based on the information associated with the compression, the plurality of compressed quality indicator values to determine a plurality of quality indicator values corresponding to the plurality of layers.

Images