Multilayer reception based on downlink channel estimation

Abstract

The invention relates to multi-layer reception based on downlink channel estimation. The invention relates to a UE with reduced complexity. In one example, the UE includes a plurality of receiving ports to support downlink multiple input multiple output (MIMO) operation. The sets may be six or more to support six or more layers for downlink MIMO operation. A first set of the receiving ports is logically grouped into a first group, and a second set of the receiving ports is logically grouped into a second group. Channel state information (CSI) transmitted by the UE to a base station may indicate a mapping of the layers (or the receiving ports) to codewords that the base station is to transmit to the UE. Additionally or alternatively, SRS transmission by the UE is associated with a particular group of the receiving ports.

Description

[0001] This application claims priority to U.S. Provisional Application No. 63 / 604,849, filed on November 30, 2023, entitled "MULTI-LAYER RECEPTION BASED ON DOWNLINK CHANNEL ESTIMATIONS", which is hereby incorporated by reference in its entirety for all purposes.

[0002] The fifth generation mobile network (5G) is a wireless standard designed to improve data transmission speed, reliability, availability, etc. Although still under development, this standard includes many details related to, for example, communication between a user equipment (UE) and a transmission and reception point (TRP) of a network to transmit and receive data. In one example, multiple-input multiple-output (MIMO) communication is used. BRIEF DESCRIPTION OF THE DRAWINGS

[0003] Figure 1 An example of a network environment according to some embodiments is illustrated.

[0004] Figure 2 An example of multi-layer reception in a user equipment (UE) with reduced complexity according to some embodiments is illustrated.

[0005] Figure 3 An example of a channel state information (CSI) report indicating codeword-to-layer mapping according to some embodiments is illustrated.

[0006] Figure 4 An example of a sequence diagram supporting a CSI report indicating codeword-to-layer mapping between a UE and a base station according to some embodiments is illustrated.

[0007] Figure 5 An example of a packet of sounding reference signal (SRS) elements and transmission chains supporting SRS transmission for downlink channel estimation associated with a receive chain group according to some embodiments is illustrated.

[0008] Figure 6 An example of a sequence diagram supporting SRS transmission for downlink channel estimation associated with a receive chain group between a UE and a base station according to some embodiments is illustrated.

[0009] Figure 7 An example of an operation flow / algorithm structure for a UE with reduced complexity to support downlink channel estimation according to some embodiments is illustrated.

[0010] Figure 8 An example of an operation flow / algorithm structure for a base station to support downlink channel estimation for communication with a UE with reduced complexity according to some embodiments is illustrated.

[0011] Figure 9 Illustrates an example of a receiving component according to some embodiments.

[0012] Figure 10 Illustrates an example of a UE according to some embodiments.

[0013] Figure 11 Illustrates an example of a base station according to some embodiments. Detailed Description

[0014] The following detailed description refers to the accompanying drawings. The same reference numerals may be used in different drawings to identify the same or similar elements. In the following description, for purposes of illustration and not limitation, specific details are set forth, such as particular structures, architectures, interfaces, techniques, etc., in order to provide a thorough understanding of various aspects of the embodiments. However, it will be apparent to those skilled in the art who benefit from the present disclosure that various aspects of the embodiments may be practiced in other examples that depart from these specific details. In some instances, descriptions of well-known devices, circuits, and methods are omitted so as not to obscure the description of the various embodiments with unnecessary detail. For the purposes of this document, the phrase "A or B" means (A), (B), or (A and B).

[0015] Generally speaking, a user equipment (UE) may communicate with a network, such as with a base station of the network. To increase data throughput, multiple-input multiple-output (MIMO) implementations may be used, where the UE may include multiple transmit chains and / or receive chains. When multiple receive chains (also referred to as receive chains or Rx chains) are implemented, downlink MIMO may be supported. Specifically, multiple downlink channels may be used to simultaneously transmit data to the UE, where these channels correspond to different receive chains. However, the quality of the downlink channels needs to be estimated before such transmission in order to apply the correct decoding to the data. One approach involves the UE estimating the quality by performing measurements on at least channel state information reference signals (CSI-RS) transmitted on such channels and transmitting a channel state information (CSI) report indicating information related to these measurements (such as a pre-coder selected or preferred by the UE) to the base station. Another method involves the base station estimating the quality, where the UE transmits sounding reference signals (SRS) and the base station performs measurements on such signals. The former method may be more suitable when reciprocity between the uplink and downlink channels is unlikely. In contrast, when such reciprocity is likely, the second method may be more suitable.

[0016] In both cases, the UE may support a large number of RF chains (e.g., six or eight). This large number creates complexity challenges related at least to the processing and / or overhead associated with determining the downlink channel quality. To address such challenges, reduced complexity may be implemented for the UE (in which case the UE may be referred to as a reduced-complexity UE). Specifically, the RF channels may be grouped together (e.g., logically) such that CSI-RS or SRS is processed based on the grouping (e.g., logical grouping) rather than individual receive chains, thereby reducing the overall complexity.

[0017] Embodiments of the present disclosure describe different techniques for configuring a reduced-complexity UE to enable downlink channel estimation to support downlink MIMO for physical downlink shared channel (PDSCH) reception. In one example related to CSI reporting, the UE may report a codeword-to-layer mapping, where each layer corresponds to one of the receive chains in the receive chain. For example, when the UE supports eight layers, the UE may include in its CSI report a mapping of a first codeword (e.g., "CW 0") to the first four layers (e.g., "layers 0, 1, 2, and 3") and a second codeword (e.g., "CW 1") to the last four layers (e.g., "layers 4, 5, 6, and 7"). In one example related to SRS, the UE may determine the number "x" of transmit ports for transmitting SRS resources and the number "y" of receive ports for receiving downlink data. Based on these two numbers, the UE may determine a mapping of the SRS resources to its receive ports. Similarly, the base station may determine this mapping. Thus, when the SRS resources are transmitted, the UE and the base station may associate the subsequent data received on that subset with the channel estimate determined according to the SRS transmission. These and other features are described further below.

[0018] The following is a glossary of terms that may be used in the present disclosure.

[0019] As used herein, the term "circuit" refers to, is part of, or includes the following: hardware components such as electronic circuits, logic circuits, processors (shared, dedicated, or groups thereof) or memories (shared, dedicated, or groups thereof) configured to provide the functionality, application specific integrated circuits (ASICs), field programmable devices (FPDs) (e.g., field programmable gate arrays (FPGAs), programmable logic devices (PLDs), complex PLDs (CPLDs), high capacity PLDs (HCPLDs), structured ASICs, or programmable systems on a chip (SoCs)), or digital signal processors (DSPs). In some embodiments, the circuit may execute one or more software or firmware programs to provide at least some of the functionality. The term "circuit" may also refer to a combination of one or more hardware elements and program code for performing the functionality of the program code (or a combination of circuits used in an electrical or electronic system). In these embodiments, the combination of the hardware element and the program code may be referred to as a particular type of circuit.

[0020] As used herein, the term "processor circuit" refers to, is part of, or includes the following: a circuit capable of sequentially and automatically performing a series of arithmetic or logical operations or recording, storing, or transmitting digital data. The term "processor circuit" may refer to an application processor, a baseband processor, a central processing unit (CPU), a graphics processing unit, a single-core processor, a dual-core processor, a triple-core processor, a quad-core processor, or any other device capable of executing or otherwise operating on computer-executable instructions such as program code, software modules, and / or functional processes.

[0021] As used herein, the term "interface circuit" refers to, is part of, or includes a circuit that enables information exchange between two or more components or devices. The term "interface circuit" may refer to one or more hardware interfaces, such as a bus, an I / O interface, a peripheral component interface, a network interface card, etc.

[0022] As used herein, the term "user equipment" or "UE" refers to a device of a remote user having radio communication capabilities and capable of describing network resources in a communication network. Additionally, the terms "user equipment" or "UE" may be considered synonymous and may be referred to as a client, a mobile phone, a mobile device, a mobile terminal, a user terminal, a mobile unit, a mobile station, a mobile user, a subscriber, a user, a remote station, an access agent, a user agent, a receiver, a radio device, a reconfigurable radio device, a reconfigurable mobile device, etc. Further, the term "user equipment" or "UE" may include any type of wireless / wired device or any computing device including a wireless communication interface.

[0023] As used herein, the term "TRP" refers to a device with radio communication capabilities, which is a network node (or more simply, a network) of a communication network and can be configured as an access node in the communication network. The access of the UE to the communication network can be at least partially managed by the TRP, whereby the UE is connected to the TRP to access the communication network. Depending on the radio access technology (RAT), the TRP may have multiple transmit and receive antenna elements for generating directional beams.

[0024] As used herein, the term "computer system" refers to any type of interconnected electronic device, computer device, or components thereof. Additionally, the term "computer system" or "system" may refer to various components of a computer that are communicatively coupled to each other. Further, the term "computer system" or "system" may refer to multiple computer devices or multiple computing systems that are communicatively coupled to each other and are configured to share computing resources or networking resources.

[0025] As used herein, the term "resource" refers to a physical or virtual device, a physical or virtual component within a computing environment, or a physical or virtual component within a particular device, such as a computer device, a mechanical device, memory space, processor / CPU time, processor / CPU utilization, processor and accelerator load, hardware time or utilization, power, input / output operations, ports or network sockets, channel / link allocation, throughput, memory utilization, storage, network, database and applications, workload units, etc. "Hardware resources" may refer to computing, storage, or networking resources provided by physical hardware elements. "Virtualized resources" may refer to computing, storage, or networking resources provided by a virtualization infrastructure to applications, devices, systems, etc. The term "network resource" or "communication resource" may refer to resources that a computer device / system can access via a communication network. The term "system resource" may refer to any kind of shared entity that provides services and may include computing resources or networking resources. System resources may be regarded as a set of coherent functions, network data objects, or services that can be accessed through a server, where such system resources reside on a single host or multiple hosts and can be clearly identified.

[0026] As used herein, the term "channel" refers to any tangible or intangible transmission medium used to convey data or a data stream. The term "channel" may be synonymous or equivalent to "communication channel", "data communication channel", "transmission channel", "data transmission channel", "access channel", "data access channel", "link", "data link", "carrier", "radio frequency carrier", or any other similar term that represents a path or medium through which data is transmitted. Additionally, as used herein, the term "link" refers to a connection established between two devices for sending and receiving information.

[0027] As used herein, the terms "instantiate", "instantiation", etc. refer to the creation of an instance. An "instance" also refers to a specific occurrence of an object, which may occur, for example, during the execution of program code.

[0028] The term "connected" may mean that two or more elements at a common communication protocol layer have an established signaling relationship with each other via a communication channel, link, interface, or reference point.

[0029] As used herein, the term "network element" refers to physical or virtualized equipment or infrastructure for providing wired or wireless communication network services. The term "network element" may be considered synonymous with or referred to as a networked computer, networked hardware, network equipment, network node, virtualized network function, etc.

[0030] The term "information element" refers to a structural element that contains one or more fields. The term "field" refers to a single content of an information element or a data element containing content. An information element may include one or more additional information elements.

[0031] Figure 1 A network environment 100 is shown according to some embodiments. The network environment 100 may include a UE 104 and a gNB 108. The gNB 108 may be a base station that provides a radio access cell. For example, the UE 104 may communicate with the gNB 108 through a 3rd Generation Partnership Project (3GPP) New Radio (NR) cell. The UE 104 and the gNB 108 may communicate through an air interface compatible with 3GPP technical specifications, such as the technical specifications that define the 5th Generation (5G) NR system standard. As further described in the figure below, the gNB 108 may be deployed as a transmission and reception point (TRP) in a cell that includes multiple TRPs.

[0032] The gNB 108 may send information (e.g., data and control signaling) in the downlink direction by mapping logical channels onto transport channels and mapping the transport channels onto physical channels. Logical channels may transfer data between the radio link control (RLC) and the MAC layer; transport channels may transfer data between the MAC and the PHY layer; and physical channels may transfer information across the air interface. Physical channels may include a physical broadcast channel (PBCH), a physical downlink control channel (PDCCH), and a physical downlink shared channel (PDSCH).

[0033] The PBCH may be used to broadcast system information that the UE 104 may use for initial access to the serving cell. The PBCH may be sent in the synchronization signal block (SSB) together with the primary synchronization signal (PSS) and the secondary synchronization signal (SSS). The SSB may be used by the UE 104 during the cell search process (including cell selection and reselection) and for beam selection.

[0034] The PDSCH can be used to transmit end-user application data, signaling radio bearer (SRB) messages, system information messages (except for example the MIB), and SI.

[0035] The PDCCH can transmit the DCI used by the scheduler of the gNB 108 to allocate both uplink and downlink resources. The DCI can also be used to provide uplink power control commands, configure the slot format, or indicate that preemption has occurred.

[0036] The gNB 108 can also send various reference signals to the UE 104. The reference signals can include demodulation reference signals (DMRS) for the PBCH, PDCCH, and PDSCH. The UE 104 can compare the received version of the DMRS with the known DMRS sequence that was sent to estimate the impact of the propagation channel. The UE 104 can then apply the inverse channel of the propagation channel during the demodulation process of the corresponding physical channel transmission.

[0037] The reference signals can also include channel state information reference signals (CSI-RS). The CSI-RS can be a multi-purpose downlink transmission signal that can be used for CSI reporting, beam management, connected-mode mobility, radio link failure detection, beam failure detection and recovery, and fine-tuning of time and frequency synchronization. Similarly, the UE can send reference signals to the gNB 108 for the gNB 108 to perform measurements (for example, in cases where reciprocity between the downlink channel and the uplink channel is not assumed). These reference signals can include, for example, sounding reference signals (SRS).

[0038] The reference signals and the information from the physical channels can be mapped to the resources of the resource grid. For a given antenna port, subcarrier spacing configuration, and transmission direction (for example, downlink or uplink), there is a resource grid. The basic unit of the NR downlink resource grid can be a resource element, which can be defined by one subcarrier in the frequency domain and one orthogonal frequency division multiplexing (OFDM) symbol in the time domain. Twelve consecutive subcarriers in the frequency domain can form a physical resource block (PRB). A resource element group (REG) can include one PRB in the frequency domain and one OFDM symbol in the time domain, for example, twelve resource elements. A control channel element (CCE) can represent a resource group for transmitting the PDCCH. One CCE can be mapped to multiple REGs, for example, six REGs.

[0039] UE 104 can use physical uplink channels to send data and control information to gNB 108. Different types of physical uplink channels are feasible, including for example the physical uplink control channel (PUCCH) and the physical uplink shared channel (PUSCH). Among them, the PUCCH carries control information from UE 104 to gNB 108, such as uplink control information (UCI), while the PUSCH carries data traffic (e.g., end-user application data) and can carry UCI.

[0040] UE 104 and gNB 108 can perform beam management operations to identify and maintain desired beams for transmissions in the uplink and downlink directions. Beam management can be applied to both the PDSCH and PDCCH in the downlink direction, and both the PUSCH and PUCCH in the uplink direction.

[0041] In one example, communication with gNB 108 and / or the base station can use channels in frequency range 1 (FR1), frequency range 2 (FR2) band, and / or higher frequency range (FRH). The FR1 band includes licensed bands and unlicensed bands. The NR unlicensed band (NR-U) includes spectrum shared with other types of radio access technologies (RATs) (e.g., LTE-LAA, WiFi, etc.). A listen-before-talk (LBT) process can be used to avoid or minimize collisions between different RATs in NR-U, whereby the device should apply a clear channel assessment (CCA) check before using the channel.

[0042] Figure 2 Example 200 of multi-layer reception in a UE with reduced complexity according to some embodiments is illustrated. As shown, gNB 208 (which is an example of gNB 108) and UE 204 (which is an example of UE 104) communicate using MIMO operations. On the downlink, UE 204 can include multiple receive chains such that multiple layers of PDSCH can be received simultaneously. UE 204 can be a UE with reduced complexity, where the receive chains (or at least the receive antennas) are logically grouped. As further described below, the signals received by the same group of receive chains are associated with the same codeword and / or correspond to channel estimates according to SRS resources and the same group of associated downlink channels for them. Figure 1 an example Figure 1 of UE 104) communicate using MIMO operations. On the downlink, UE 204 can include multiple receive chains such that multiple layers of PDSCH can be received simultaneously. UE 204 can be a UE with reduced complexity, where the receive chains (or at least the receive antennas) are logically grouped. As further described below, the signals received by the same group of receive chains are associated with the same codeword and / or correspond to channel estimates according to SRS resources and the same group of associated downlink channels for them.

[0043] For illustrative purposes, Figure 2Eight receive chains are shown (each pair of receive antennas is shown using an "X"), and the eight receive chains are grouped into two groups: a first receive chain 231 (a logical group of four receive chains) and a second receive chain 232 (another logical group of four receive chains). However, the embodiments are not limited to this. Instead, different numbers of receive chains are possible (e.g., six receive chains) and / or different numbers of groups are possible.

[0044] When the gNB 208 transmits downlink information to the UE 204, the information is decoded into codewords. Among other factors, the number of codewords can depend on the number of layers. The codewords can be scrambled, modulated, layer mapped, precoded, resource element mapped, and OFDM signal mapped before being transmitted by the gNB 208. Layer mapping can map the codewords to specific layers of the PDSCH. Each layer can be associated with a specific precoder. In the case where there is no reciprocity between the uplink and downlink channels (e.g., in the case of frequency division duplexing (FDD)), the precoder can be indicated by the UE 204 in the CSI report. In the case where there is reciprocity between the uplink and downlink channels (e.g., in the case of time division duplexing (TDD)), the gNB 208 can determine the precoder based on the uplink SRS transmission performed by the UE 204.

[0045] More specifically, there are different modes that support downlink MIMO operation. The first mode does not use downlink and uplink channel reciprocity (e.g., FDD band). Here, the UE 204 measures the CSI based on CSI-RS sent from the gNB 208 using multiple ports and reports the CSI. The CSI includes PMI (precoding matrix indicator), RI (rank indicator), CQI (channel quality indicator), CRI (CSI-RS resource indicator), LI (layer indicator), etc. There are also different types of CSI codebooks. Type I codebook represents low-resolution CSI feedback but supports up to, for example, eight layers. Type II codebook represents high-resolution CSI feedback but only supports up to 4 layers.

[0046] The second mode uses downlink and uplink channel reciprocity (e.g., TDD band). Here, the gNB 208 configures the UE 204 to transmit SRS using antenna switching, and the antenna switching is configured with an SRS-ResourceSet in which the usage is set to "antennaSwitching". The gNB 208 estimates the uplink channel based on the antenna-switching SRS sent from the UE 208 and obtains downlink channel information based on downlink and uplink channel reciprocity. The gNB 208 can determine the downlink precoder or use a downlink port selection codebook to refine the downlink precoder.

[0047] The layers used for simultaneous PDSCH transmission can be grouped (e.g., logically). Referring back to the exemplary usage of eight layers, Figure 2 two groups are shown: a first layer group 211 (a logical group of layers "0", "1", "2", and "3") and a second layer group 212 (a logical group of layers "4", "5", "6", and "7"). Of course, different groupings of the eight layers are possible and / or different numbers of layers and / or groups are possible. The first codeword is mapped to the first layer group 211, and the second codeword is mapped to the second layer group 212. The first layer group 211 can be associated with a first receive chain 231, and the second layer group 212 can be associated with a second receive chain 232. Thus, the first receive chain 231 is used to receive the first codeword, and the second receive chain 232 is used to receive the second codeword.

[0048] Thus, up to eight-layer PDSCH (more than four layers) is transmitted using two codewords (CWs). A UE 204 with six or eight receive antennas can distribute its receive antennas into two groups, with each group available for receiving one CW. When the gNB 208 transmits eight-layer PDSCH, each CW contains four layers. At the UE 204, each group of four receive antennas can be used to handle one of the CWs.

[0049] In the above example where four layers are grouped into two layer groups, eight receive antennas are also grouped into two antenna groups, and two codewords, the first codeword is associated with the first layer group and the first antenna group (e.g., the first layer group 211 and the first receive chain 231), and the second codeword is associated with the second layer group and the second antenna group (e.g., the second layer group 212 and the second receive chain 232). The first codeword is transmitted using four downlink channels between the gNB 208 and the UE 204. Similarly, the second codeword is transmitted using four other downlink channels between the gNB 208 and the UE 204.

[0050] Channel estimates for each downlink channel (or a set of four downlink channels) are needed to determine the precoding to be used for each of the two codewords. As explained above in this document, the UE 204 can determine the precoding based on the CSI reference signal and indicate the precoding to the gNB 208, or the gNB 208 can determine the precoding based on the SRS transmission from the UE 204. In both cases, the UE 204 and the gNB 208 can exchange information about the logical grouping to achieve channel estimation. For example, in the case of CSI reporting (or when reciprocity is not used), the UE 204 can indicate the codeword-to-layer mapping (or equivalently, layer-to-codeword mapping) to the gNB 208 such that the relevant precoding is applied to the codewords. In the case of SRS transmission on the uplink channel (or when reciprocity is used), the downlink channel is reciprocal to the uplink channel. A set of receive antennas receives the codewords transmitted on these downlink channels. The precoding associated with these downlink channels is applied to the codewords. A grouping needs to be determined such that the codewords can be processed correctly.

[0051] Figure 3 Example 300 illustrates a CSI report indicating a codeword-to-layer mapping according to some embodiments. The UE (e.g., Figure 2 the UE 204) includes multiple receive chains (or at least multiple receive antennas), which are grouped in a first receive chain group 350 (or at least a first receive antenna group) and a second receive chain group 360 (or at least a second receive antenna group). The UE can indicate the codeword-to-layer mapping (or equivalently, layer-to-codeword mapping) to the base station (e.g., Figure 2 the gNB 208). The mapping can be indicated in the CSI report 302 transmitted to the base station. In one example, the mapping indicates the layers on the UE side associated with the same codeword to be transmitted by the base station. These layers correspond to the receive chain groups (or receive antenna groups). Then, the base station can process the codewords by using the precoding information associated with these layers before transmitting the codewords to the UE.

[0052] In Figure 3 the illustration, the mapping indicates that the first codeword 310 (e.g., CW “0”) is associated with the first layer group 330. The mapping also indicates that the second codeword 320 (e.g., CW “1”) is associated with the second layer group 340. The first layer group 330 can include multiple layers, while the second layer group 340 can include multiple layers. The first layer group 330 is associated with a first receive chain group 350 (or a first receive antenna group) including multiple receive chains (or at least one receive antenna). The second layer group 340 is associated with a second receive chain group 360 (or a second receive antenna group) including multiple receive chains.

[0053] Returning to the example of eight layers, each receive group 350 and 360 includes four receive antennas. The first layer group 330 includes layers "0", "1", "2", and "3". The second layer group 340 includes layers "4", "5", "6", and "7". The first codeword 310 corresponds to any codeword to be transmitted by the base station and indexed by index "0" (e.g., CW "0"). The second codeword 310 corresponds to any codeword to be transmitted by the base station and indexed by index "1" (e.g., CW "1"). Thus, the mapping in the CSI report 302 indicates that CW "0" is associated with layers "0", "1", "2", and "3", while CW "1" is associated with layers "4", "5", "6", and "7". When processing CW "0" to be transmitted to the UE, the base station applies precoding information related to layers "0", "1", "2", and "3". When processing CW "1" to be transmitted to the UE, the base station applies precoding information related to layers "4", "5", "6", and "7".

[0054] Figure 4 An example of UE 204 ( Figure 2 example of UE 410) and base station 420 ( Figure 2 example of gNB 208) supporting a sequence diagram of a CSI report indicating codeword to layer mapping is illustrated in example 400. As shown, UE 410 transmits capability information to base station 420 (e.g., via radio resource control (RRC) signaling). This capability information reports the maximum number of layers supported by UE 410 for PDSCH reception. In one example, this number is greater than four (e.g., six, eight, or different positive integers greater than four). In one example, UE 410 reports the maximum number of spatial multiplexing layers supported by UE 410 for downlink reception by using RRC signaling including the maxNumberMIMO LayersPDSCH information element (IE). maxNumberMIMO LayersPDSCH indicates the maximum number as a value and is reported by UE 410 per component carrier per feature set (FSPC) (e.g., per band combination (BC) per band per component carrier). Candidate values for MIMO LayersDL can be six or eight (e.g., extended to include "sixLayers"). One example is as follows:

[0055] MIMO-LayersDL::=ENUMERATED{twoLayers,fourLayers,sixLayers,eightLayers}

[0056] FeatureSetDownlinkPerCC::=SEQUENCE{

[0057] supportedSubcarrierSpacingDL SubcarrierSpacing,

[0058] supportedBandwidthDL SupportedBandwidth,

[0059] channelBW-90mhz ENUMERATED{supported}

[0060] maxNumberMIMO-LayersPDSCH MIMO-LayersDL

[0061] supportedModulationOrderDL ModulationOrder

[0062] }

[0063] Next, the base station 420 transmits configuration information to the UE 410 based on this capability information. The configuration information can configure the UE 410 to use a specific number of layers (e.g., up to the maximum number supported by the UE) for PDSCH reception. The configuration information can indicate the maximum rank (e.g., the maximum number of layers) that the UE 410 needs to report. The maximum rank can be represented as D maxRank . There can be different options for indicating D maxRank to the UE410. In one example, D maxRank is indicated in a restricted configuration (e.g., in CodebookConfig). The rank restriction is a bitmap. D maxRank can be the maximum rank with the corresponding bit configured to "1". For example, the bitmap can include bits, each bit corresponding to a rank (e.g., the first bit corresponds to rank one, the second bit corresponds to rank two, etc.). One or more bits can be set to "1". Among all the bits set to "1", the bit corresponding to the maximum number of layers determines the maximum rank. For type I single-panel codebooks, D maxRank is configured as typeI-SinglePanel-ri-Restriction. For type I multi-panel codebooks, D maxRank is configured as ri-Restriction. For type II regular codebooks, D maxRank is configured as typeII-RI-Restriction. For type II port selection codebooks, D maxRank is configured as typeII-PortSelectionRI-Restriction. In a second example, the maximum rank (e.g., D maxRank) It can be configured separately from the rank restriction configuration, such as being included as its own IE in CodebookConfig or CSI-ReportConfig.

[0064] Once the UE 410 is configured, the base station 420 can transmit CSI-RS to the UE 410 to perform measurements thereon and generate a CSI report. For example, CSI-RS is transmitted by using CSI-RS resources on different downlink channels.

[0065] The UE 410 receives the CSI-RS and performs measurements thereon, then generates a CSI report and transmits it to the base station 420. In addition to including CSI such as PMI, RI, CQI, CRI, LI, etc., the CSI report may also include mapping information (e.g., layer to codeword mapping).

[0066] When the UE 410 reports that the UE 410 supports up to six or eight layers of PDSCH reception, for UEs with reduced complexity, the CSI report may contain additional layer to codeword mapping information, and one or more restrictions may be considered. Specifically, when the network (e.g., the base station 420) configures the maximum number of layers of the CSI report to be greater than four (e.g., “D maxRank >4”), the layer to codeword mapping report is enabled. Additionally or alternatively, when the UE 410 reports more than four layers of CSI (e.g., in the CSI report, the UE 410 includes CSI for more than four layers), the layer to codeword mapping report is enabled. In both cases, the UE 410 may report the number of layers of the CSI (e.g., the actual rank) in the RI of the reported CSI.

[0067] When the UE 410 reports that the UE 410 supports up to six or eight layers of PDSCH reception, for a UE with reduced complexity, and when the UE 410 can report additional layer-to-codeword mapping, a fixed number of layers can be mapped to codewords. Here, the mapping indicates the number of layers associated with a codeword (not necessarily identifying those layers). For example, the mapping indicates that the first codeword is to be processed based on a first subset of six or more layers, and the second codeword is to be processed based on a second subset of six or more layers, without necessarily identifying the layers in the two subsets. Consider an illustration where the UE 410 reports five, six, seven, or eight layers. In a five-layer CSI, the mapping is for "two layers to one codeword and three layers to another codeword": the first codeword contains two layers, and the second codeword contains three layers. In a six-layer CSI, the mapping is for "three layers to one codeword and three layers to another codeword": the first codeword contains three layers, and the second codeword contains three layers. In a seven-layer CSI, the mapping is for "three layers to one codeword and four layers to another codeword": the first codeword contains three layers, and the second codeword contains four layers. In an eight-layer CSI, the mapping is for "four layers to one codeword and four layers to another codeword": the first codeword contains four layers, and the second codeword contains four layers.

[0068] When the UE 410 reports that the UE 410 supports up to six or eight layers of PDSCH reception, for a UE with reduced complexity, and when the UE 410 can report additional layer-to-codeword mapping, the CSI can be partitioned to indicate the mapping in at least a portion thereof. The bit width and interpretation of the mapping report can depend on the assumption of the number of layers used for the PDSCH. For example, the CSI can be partitioned into multiple parts, including a first part (here called part "1") and a second part (here called part "2"). In one example, the first part has a fixed bit size, while the second part has a variable bit size and indicates the mapping. The first part indicates the rank (e.g., as RI). The variable bit size of the second part is based on that rank. Specifically, the bit width and interpretation of the mapping report depend on the rank (e.g., RI) reported in CSI part "1". The first part can include other CSI information (e.g., PMI, RI, CQI, CRI, LI, etc.). The larger the number of layers reported (e.g., the larger the rank indicated in the first part), the larger the bit size of the second part, such that the necessary bits are included in the second part to indicate the mapping. In another example, the two parts are used. But here, the first part (with a fixed bit size) indicates the mapping. In this example, the bit width and interpretation of the mapping in the first part are based on at least one of the following: the first maximum rank indicated by the configuration information (e.g., D maxRank) The second largest rank indicated by the capability information (e.g., maxNumberMIMO LayersPDSCH), or the third largest possible rank (e.g., assuming a maximum number of layers or a maximum rank, such as eight, and the number of bits required for mapping in the first part is set according to this maximum rank).

[0069] When the UE 410 reports that the UE 410 supports reception of up to six or eight layers of PDSCH, for a UE with reduced complexity, and when the UE 410 can report additional layer-to-codeword mapping, a specific layer associated with a specific codeword can be identified in the CSI report. In one example, the CSI report indicates the mapping by using a bitmap. Each bit of the bitmap corresponds to a layer, and the value of the bit indicates whether the layer is mapped to the first codeword or the second codeword. The layer with an associated bitmap entry equal to "1" is mapped to one CW, and the layer with a bitmap entry equal to "0" is mapped to the other CW. Consider an illustration where the UE 410 reports five, six, seven, or eight layers. In a five-layer CSI, the bitmap is set to "00101". Thus (from the least significant bit to the most significant bit), the first and third layers in the reported PMI are mapped to one CW, and the second, fourth, and fifth layers in the reported PMI are mapped to the other CW. In a six-layer CSI, the bitmap is set to "100101". Thus, the first, third, and sixth layers in the reported PMI are mapped to one CW, and the second, fourth, and fifth layers in the reported PMI are mapped to the other CW. In a seven-layer CSI, the bitmap is set to "0100101". Thus, the first, third, and sixth layers in the reported PMI are mapped to one CW, and the second, fourth, fifth, and seventh layers in the reported PMI are mapped to the other CW. In an eight-layer CSI, the bitmap mapping is set to "10100101". Thus, the first, third, sixth, and eighth layers in the reported PMI are mapped to one CW, and the second, fourth, fifth, and seventh layers in the reported PMI are mapped to the other CW. In another example, a bitmap is not used. Instead, the CSI report indicates the mapping by using multiple bits, where the total number of bits used is based on the number of layers associated with the CSI report. Specifically, the "combination coefficient C(R,k)" is used to determine the total number of bits, and the values of these bits are set to indicate a specific mapping. "C(R,k)" represents the number of possible selections of "k" layers from "R" layers. Here, an illustration where the UE 410 reports five, six, seven, or eight layers is also considered. In a five-layer CSI, a total of "C(5,2)=10" selections are possible. Thus, four bits are used to indicate the mapping. In a six-layer CSI, a total of "C(6,3)=20" selections are possible. Thus, five bits are used to indicate the mapping. In a seven-layer CSI, a total of "C(7,3)=35" selections are possible. Thus, six bits are used to indicate the mapping. In an eight-layer CSI, a total of "C(8,4)=70" selections are possible. Thus, seven bits are used to indicate the mapping. This example can reduce the total number of bits required compared to the bitmap example (e.g., reducing one bit in the case of each layer in different layers).

[0070] Figure 5 Example 500 illustrates an SRS element and a packet of transmit chains that support SRS transmission for downlink channel estimation associated with a receive chain group according to some embodiments. Generally, SRS antenna switching can be implemented so that a network (e.g., its base station) can estimate the channel quality of one or more downlink channels based on uplink channel estimation and based on downlink and uplink channel reciprocity. Antenna switching can be represented as xTyR, where "x" and "y" are positive integers and "y≥x". "x" represents the number of transmit ports (or transmit antennas or transmit chains) used on the uplink, and "y" represents the number of receive ports (or receive antennas or receive chains) used on the downlink that has reciprocity with the uplink. If "x" is one, the uplink includes one uplink channel. If "x" is greater than one, the uplink includes more than one uplink channel. Similarly, if "y" is one, the downlink includes one downlink channel (equivalently, one layer for PDSCH reception). If "y" is greater than one, the downlink includes more than one downlink channel (equivalently, more than one layer for PDSCH reception). Thus, for xTyR SRS with antenna switching, the UE uses "x" transmit ports to probe "y" receive ports. Specifically, the UE uses "x" transmit ports to transmit the SRS. These "x" transmit ports correspond to "x" uplink channels. The base station estimates the "x" uplink channels. The channel quality of the "y" reciprocal downlink channels is assumed to be the same as the uplink channel estimation. These "y" downlink channels correspond to the "y" receive ports of the UE.

[0071] For six-layer and eight-layer reception (6Rx and 8Rx), the following SRS antenna switching can be supported: 1T6R, 2T6R, 1T8R, 2T8R, 4T8R, and 8T8R. In the case of 1T6R, one transmit port can be used to sequentially transmit six SRS resources to probe six receive ports. In the case of 2T6R, three SRS resources can be sequentially transmitted to probe six receive ports, where each transmission uses two transmit ports. In the case of 1T8R, one transmit port can be used to sequentially transmit eight SRS resources to probe eight receive ports. In the case of 2T8R, four SRS resources can be sequentially transmitted to probe eight receive ports, where each transmission uses two transmit ports. In the case of 4T8R, two SRS resources can be sequentially transmitted to probe eight receive ports, where each transmission uses four transmit ports. In the case of 8T8R, one SRS resource can be transmitted to probe eight receive ports, where this transmission uses eight transmit ports.

[0072] In the case of a base station, the base station needs to determine the precoding of the codewords to be transmitted on the "y" downlink channels corresponding to the "y" receive ports of the UE, where these receive ports are associated with "x" transmit ports for the purpose of SRS sounding using antenna switching. Therefore, the base station needs to determine the SRS resource grouping indicating that the same SRS resource is associated with a set of different SRS ports. Similarly, the UE needs to determine such SRS resource grouping for its processing of the codeword when receiving the codeword. Information about the SRS resource grouping can be exchanged between the base station and the UE (e.g., via RRC signaling) or can be defined in the technical specifications followed by both the base station and the UE (e.g., in this case, information exchange may not be required).

[0073] When the UE reports that it supports up to six or eight layers of PDSCH reception, for reduced complexity, SRS enhancements can be considered to group different receive ports. Such grouping (referred to herein as SRS resource grouping) can be at different levels. In one example, the SRS resource grouping indicates that the same SRS resource is associated with a set of different SRS ports (e.g., in the same SRS-Resource, different SRS ports are grouped). In another example, the SRS resource grouping indicates that the same set of SRS resources is associated with a set of different SRS resources (e.g., in the same SRS-ResourceSet, different SRS-Resources are grouped). In another example, the SRS resource grouping indicates that a subset of six or more layers for PDSCH reception is associated with a set of different SRS resource sets (e.g., in the same layer subset, different SRS-ResourceSets are grouped).

[0074] As Figure 5 shown, the SRS resource grouping 502 associates the SRS element 510 with the "x" transmit ports 520 and the "y" receive ports 530 in the xTyR configuration 540 for SRS antenna switching. The SRS element 510 can be one or more transmit ports (in which case the SRS element 510 and the "x" transmit ports 520 are the same), one or more SRS resources, or one or more SRS resource sets.

[0075] Examples of 1T6R, 2T6R, 1T8R, 2T8R, 4T8R, and 8T8R are presented. The following information can be indicated by the SRS resource set 502. For 1T6R, six SRS resources are used to probe six receive ports. Two groups can be indicated, each corresponding to three SRS resources and three receive ports. For 2T6R, three SRS resources are used to probe six receive ports. Two groups can be indicated, one corresponding to three SRS resources and three receive ports, and the other corresponding to another three SRS resources and three receive ports. For 1T8R, eight SRS resources are used to probe eight receive ports. Two groups can be indicated, each corresponding to four SRS resources and four receive ports. For 2T8R, four SRS resources are used to probe eight receive ports. Two groups can be indicated, one corresponding to four SRS resources and four receive ports. For 4T8R, two SRS resources are used to probe eight receive ports. Two groups can be indicated, one corresponding to one SRS resource and four receive ports. For 8T8R, one SRS resource is used to probe eight receive ports. Two groups can be indicated, each corresponding to four receive ports.

[0076] Figure 6 Example 600 of a sequence diagram supporting SRS transmission for downlink channel estimation associated with a receive chain group between UE 610 and base station 620 according to some embodiments is illustrated. As shown, UE 610 transmits capability information (e.g., via radio resource control (RRC) signaling) to base station 620. Similar to Figure 4 Example 400, the capability information reports the maximum number of layers supported by UE 610 for PDSCH reception. In one example, this number is greater than four (e.g., six, eight, or a different positive integer greater than four). Next, base station 620 transmits configuration information to UE 610 based on this capability information. Similar to Figure 4 Example 400, this configuration information can configure UE 610 to use a specific number of layers (e.g., up to the maximum number supported by the UE) for PDSCH reception.

[0077] Given the number of configured layers or the number of layers to be used by UE 610, the UE may determine SRS packet information. This SRS packet information does not need to be signaled from the base station (e.g., via RRC signaling). Instead, the SRS packet information may be stored in the memory of UE 610, where the information is defined according to a technical specification followed by both UE 610 and base station 620 and may be looked up from the memory given the number of layers and / or the xTyR configuration of the UE. Based on the SRS packet information (e.g., a certain SRS resource is associated with a group of receive ports), UE 610 may transmit an SRS transmission to base station 620. Depending on the xTyR configuration of UE 610, the SRS transmission may include SRS resources on one or more uplink channels, where some or all of the "y" receive ports are grouped together by the packet information and associated with the SRS resource. Upon receiving the SRS transmission, base station 620 may process the SRS transmission by at least processing the SRS resource. To this end, base station 620 may also determine the SRS packet information. Here too, the SRS packet information may be stored in the memory of base station 620, where the information is defined according to the technical specification and may be looked up from the memory given the number of configured layers and / or the xTyR configuration of the UE. The SRS transmission processing may include performing different types of measurements (e.g., reference signal received power (RSRP), reference signal received quality (RSRQ), etc.) to determine the relevant precoding information for each group of layers (or, correspondingly, the "y" receive ports of UE 610). The precoding information is then used to process the codewords mapped to a group of layers.

[0078] In one example, when the UE 610 reports that it supports PDSCH reception of up to six or eight layers, for UEs with reduced complexity, SRS enhancement can be considered to group different receive ports of 1T6R. In one option, in an SRS-ResourceSet that is set to "antennaSwitching", six SRS-Resources are configured. Three of the six SRS-Resources are grouped together and can be associated with three of the six receive ports. Additionally, the last three SRS-Resources are grouped together and can be associated with the remaining three receive ports. In this option, the order of the SRS-Resources can be determined based on the SRS-ResourceId (e.g., the three SRS resources with the three smallest identifiers are associated with the first group), or the order of the SRS-Resources configured in the corresponding SRS-ResourceSet. In another option, in two SRS-ResourceSets that are set to "antennaSwitching", three SRS-Resources are configured in each SRS-ResourceSet. The first SRS-ResourceSet corresponds to the first group that can be associated with three of the six receive ports, and the second SRS-ResourceSet corresponds to the second group that can be associated with the remaining three receive ports.

[0079] In one example, when the UE 610 reports that it supports PDSCH reception of up to six or eight layers, for UEs with reduced complexity, SRS enhancement can be considered to group different receive ports for 2T6R. In one option, in an SRS-ResourceSet where the SRS is set to "antennaSwitching", three SRS-Resources are configured. These three SRS-Resources are grouped together and can be associated with three of the six receive ports. In another SRS-ResourceSet where the SRS is set to "antennaSwitching", three other SRS-Resources are configured. Again, these three SRS-Resources are grouped together and can be associated with the remaining three receive ports. In this option, the order of the SRS-Resources can be determined based on the SRS-ResourceId or the order of the SRS-Resources can be configured in the corresponding SRS-ResourceSet. In another option, the first SRS-ResourceSet corresponds to a first group that can be associated with three of the six receive ports, and the second SRS-ResourceSet corresponds to a second group that can be associated with the remaining three receive ports.

[0080] In one example, when the UE 610 reports that it supports PDSCH reception of up to six or eight layers, for UEs with reduced complexity, SRS enhancement can be considered to group different receive ports for 1TR8. In one option, in an SRS-ResourceSet where the SRS is set to "antennaSwitching", eight SRS-Resources are configured. Four of the eight SRS-Resources (e.g., the first four SRS-Resources) are grouped together, and this group can be associated with one set of receive ports. The remaining four SRS-Resources (e.g., the last four SRS-Resources) are grouped together, and this group can be associated with a different set of receive ports. In this option, the order of the SRS-Resources can be determined based on the SRS-ResourceId or the order of the SRS-Resources can be configured in the corresponding SRS-ResourceSet. In another option, in two SRS-ResourceSets where the SRS is set to "antennaSwitching", four SRS-Resources are configured in each SRS-ResourceSet. The first SRS-ResourceSet corresponds to the first group, and the second SRS-ResourceSet corresponds to the second group.

[0081] In one example, when the UE 610 reports that it supports up to six or eight layers of PDSCH reception, for UEs with reduced complexity, SRS enhancement can be considered to group different receiving ports of 2TR8. In one option, in an SRS-ResourceSet set to "antennaSwitching", four SRS-Resources are configured. Two SRS-Resources (e.g., the first two SRS-Resources) are grouped together and can be associated with a set of receiving ports. The other two SRS-Resources (e.g., the last two SRS-Resources) are grouped together and can be associated with a different set of receiving ports. In this option, the order of the SRS-Resources can be determined based on the SRS-ResourceId or the order of the SRS-Resources can be configured in the corresponding SRS-ResourceSet. In another option, in two SRS-ResourceSets set to "antennaSwitching", two SRS-Resources are configured in each SRS-ResourceSet. The first SRS-ResourceSet corresponds to the first group, and the second SRS-ResourceSet corresponds to the second group.

[0082] In one example, when the UE 610 reports that it supports up to six or eight layers of PDSCH reception, for UEs with reduced complexity, SRS enhancement can be considered to group different receiving ports of 4TR8. In one option, in an SRS-ResourceSet set to "antennaSwitching", two SRS-Resources are configured. One of the two SRS-Resources (e.g., the first SRS-Resource) is associated with a set of receiving ports. The other SRS resource (e.g., the last SRS-Resource) is associated with a different set of receiving ports. In this option, the order of the SRS-Resources can be determined based on the SRS-ResourceId or the order of the SRS-Resources can be configured in the corresponding SRS-ResourceSet. In another option, in two SRS-ResourceSets set to "antennaSwitching", one SRS-Resource is configured in each SRS-ResourceSet. The first SRS-ResourceSet corresponds to the first group, and the second SRS-ResourceSet corresponds to the second group.

[0083] In one example, when the UE 610 reports that it supports PDSCH reception with up to six or eight layers, for a UE with reduced complexity, SRS enhancement may be considered to group different reception ports of 8TR8. In one option, in an SRS-ResourceSet configured with "antennaSwitching", one SRS-Resource is configured with eight ports. Four SRS ports (e.g., the first four SRS ports) or equivalently four reception ports are grouped together. The other four SRS ports (e.g., the last four SRS ports) or equivalently the four remaining reception ports are grouped together.

[0084] Figure 7 An example of an operation flow / algorithm structure 700 for a UE with reduced complexity to support downlink channel estimation according to some embodiments is illustrated. The operation flow / algorithm structure 700 may be executed or implemented by a UE (such as any of the UEs described herein) or its components (e.g., the processor 1004).

[0085] The operation flow / algorithm structure 700 may include: at 702, generating capability information indicating that the UE supports six or more layers for physical downlink shared channel (PDSCH) reception, wherein a first subset of the six or more layers is associated with a first set of receive chains of the UE and a second subset of the six or more layers is associated with a second set of receive chains of the UE to support downlink multiple-input multiple-output (MIMO) operation. The capability information may include an IE indicating the number of layers supported by the UE. The IE may be axNumberMIMO LayersPDSCH reported per FSPC and include "sixLayers" as an explicit value when the UE supports six layers.

[0086] The operation flow / algorithm structure 700 may include: at 704, processing configuration information indicating a resource configuration for a reference signal, wherein the reference signal is one of a channel state information reference signal (CSI-RS) or a sounding reference signal (SRS). The configuration information may also configure the UE to use a specific number of layers (e.g., the maximum rank per FSPC). The maximum rank may be included in CodebookConfig or CSI-ReportConfig.

[0087] The operation flow / algorithm structure 700 may include: at 706, generating a channel state information (CSI) report that indicates a mapping of the six or more layers to two or more codewords such that a first codeword is mapped to a first subset of the six or more layers and a second codeword is mapped to a second subset of the six or more layers. For example, the UE receives CSI-RS from a base station and performs measurements thereon to generate the CSI report. The report may indicate the number of layers to be mapped to a codeword (without identifying the layers) and / or may identify the specific layers mapped to a codeword by using a bitmap or specific bits in a first part or a second part of the CSI report.

[0088] The operation flow / algorithm structure 700 may include: at 708, determining an SRS resource set based on a first number of transmit ports to be used by the UE for SRS transmission and a second number of receive ports to be used by the UE for PDSCH reception. For example, the set may be determined from the UE's memory and may be used to associate an uplink SRS transmission with a set of receive ports.

[0089] Operations 706 to 708 may be performed alternately with each other or in combination with each other (in which case they may be performed in parallel or sequentially).

[0090] Figure 8 An example of an operation flow / algorithm structure 800 for a base station to support downlink channel estimation for communication with a complexity-reduced UE according to some embodiments is illustrated. The operation flow / algorithm structure 800 may be executed or implemented by a base station (such as any of the base stations described herein) or its components (e.g., processor 1104).

[0091] The operation flow / algorithm structure 800 may include: at 802, receiving from the UE capability information indicating that the UE supports six or more layers for physical downlink shared channel (PDSCH) reception, wherein a first subset of the six or more layers is associated with a first set of receive chains of the UE and a second subset of the six or more layers is associated with a second set of receive chains of the UE to support downlink multiple-input multiple-output (MIMO) operation. The capability information may be received via RRC signaling and may include an IE indicating the number of layers supported by the UE. The IE may be axNumberMIMOLayersPDSCH reported per FSPC and includes "sixLayers" as an explicit value when the UE supports six layers.

[0092] The operation procedure / algorithm structure 800 may include: at 804, transmitting configuration information to the UE indicating a resource configuration for a reference signal, where the reference signal is one of a channel state information reference signal (CSI-RS) or a sounding reference signal (SRS). The configuration information may be transmitted via RRC signaling and configure the UE to use a specific number of layers (e.g., the maximum rank per FSPC). The maximum rank may be included in CodebookConfig or CSI-ReportConfig.

[0093] The operation procedure / algorithm structure 800 may include: at 806, receiving a channel state information (CSI) report from the UE, the channel state information (CSI) report indicating a mapping of the six or more layers to two or more codewords such that a first codeword is mapped to a first subset of the six or more layers and a second codeword is mapped to a second subset of the six or more layers. For example, the base station transmits CSI-RS to the UE, and the UE then performs measurements on it to generate a CSI report. The report is transmitted from the UE and may indicate the number of layers to be mapped to codewords (without identifying the layers) and / or may identify the specific layers mapped to codewords by using a bitmap or specific bits in the first or second part of the CSI report.

[0094] The operation procedure / algorithm structure 800 may include: at 808, determining an SRS resource grouping based on a first number of transmit ports to be used by the UE for SRS transmission and a second number of receive ports to be used by the UE for PDSCH reception. For example, the grouping may be determined from the memory of the base station and may be used to associate uplink SRS transmission with a set of receive ports of the UE (e.g., not necessarily identifying the ports, or equivalently associating with layers).

[0095] Operations 806 to 808 may be performed alternately with each other or in combination with each other (in which case they may be performed in parallel or sequentially).

[0096] Figure 9 Illustrated is a receiving component 900 of a UE 104 (e.g., Figure 1 the UE 104 and any other UE described herein). The receiving component 900 may include an antenna panel 904, which includes a plurality of antenna elements. Panel 904 is shown as having four antenna elements, but other embodiments may include other numbers. Multiple antenna panels may also be included.

[0097] The antenna panel 904 can be coupled to an analog beamforming (BF) component, which includes a plurality of phase shifters 908(1) to 908(4). The phase shifters 908(1) to 908(4) can be coupled to the radio frequency (RF) chain 909. The RF chain 909 can amplify the received analog RF signal, down-convert the RF signal to baseband, and convert the analog baseband signal to a digital baseband signal that can be provided to the baseband processor for further processing.

[0098] In various embodiments, control circuitry that may reside in the baseband processor can provide BF weights (e.g., W1 to W4) that can represent phase shift values to the phase shifters 908(1) to 908(4) to provide a receive beam at the antenna panel 904. These BF weights can be determined based on channel-based beamforming.

[0099] Figure 10 Illustrated is a UE 1000 according to some embodiments. The UE 1000 can be similar to Figure 1 the UE 104 and any other UE described herein and can be substantially interchangeable with them.

[0100] Similar to the description of the UE 104 above, the UE 1000 can be any movable or immovable computing device, such as a mobile phone, computer, tablet, industrial wireless sensor (e.g., microphone, carbon dioxide sensor, pressure sensor, humidity sensor, thermometer, motion sensor, accelerometer, laser scanner, fluid level sensor, inventory sensor, voltage / current meter, and actuator), video surveillance / monitoring device (e.g., camera and video camera), wearable device, or relaxation IoT device. In some embodiments, the UE can be a reduced-capacity UE or an NR-Light UE.

[0101] The UE 1000 can include a processor 1004, an RF interface circuit 1008, a memory / storage device 1009, a user interface 1016, sensors 1020, a driver circuit 1022, a power management integrated circuit (PMIC) 1024, and a battery 1028. The components of the UE 1000 can be implemented as integrated circuits (ICs), parts of integrated circuits, discrete electronic devices, or other modules, such as logic components, hardware, software, firmware, or combinations thereof. Figure 10 The block diagram is intended to show a high-level view of some of the components of the UE 1000. However, some of the components shown may be omitted, additional components may exist, and different arrangements of the shown components may occur in other specific implementations.

[0102] The components of the UE 1000 may be coupled to various other components via one or more interconnects 1032, which may represent any type of interface, input / output, bus (local, system, or expansion), transmission line, trace, optical interconnect, etc., that allows various circuit components (on common or different chips or chip sets) to interact with each other.

[0103] The processor 1004 may include processor circuitry such as baseband processor circuitry (BB) 1004A, central processing unit circuitry (CPU) 1004B, and graphics processing unit circuitry (GPU) 1004C. The processor 1004 may include any type of circuitry or processor circuitry that executes or otherwise operates computer-executable instructions (such as program code, software modules, or functional procedures from the memory / storage 1009) to cause the UE 1000 to perform the operations described herein.

[0104] In some embodiments, the baseband processor circuitry 1004A may access the communication protocol stack 1036 in the memory / storage 1009 to communicate via a 3GPP-compatible network. Generally, the baseband processor circuitry 1004A may access the communication protocol stack to: perform user plane functions at the PHY layer, MAC layer, RLC layer, PDCP layer, SDAP layer, and PDU layer; and perform control plane functions at the PHY layer, MAC layer, RLC layer, PDCP layer, RRC layer, and non-access stratum (NAS) layer. In some embodiments, the PHY layer operations may additionally / alternatively be performed by components of the RF interface circuitry 1008.

[0105] The baseband processor circuitry 1004A may generate or process baseband signals or waveforms that carry information in a 3GPP-compatible network. In some embodiments, the waveforms for NR may be based on cyclic prefix OFDM (CP-OFDM) in the uplink or downlink, and discrete Fourier transform spread OFDM (DFT-S-OFDM) in the uplink.

[0106] The baseband processor circuitry 1004A may also access the group information 1024 from the memory / storage 1009 to determine the multiple repeated search space groups in which the PDCCH may be transmitted.

[0107] Memory / storage device 1012 may include any type of volatile or non-volatile memory that may be distributed throughout the UE 1000. In some embodiments, some of the memory / storage devices in the memory / storage device 1012 may be located on the processor 1004 itself (e.g., L1 cache and L2 cache), while other memory / storage devices 1012 are located external to the processor 1004 but may be accessed via a memory interface. The memory / storage device 1012 may include any suitable volatile or non-volatile memory, such as but not limited to dynamic random access memory (DRAM), static random access memory (SRAM), erasable programmable read only memory (EPROM), electrically erasable programmable read only memory (EEPROM), flash memory, solid state memory, or any other type of memory device technology.

[0108] The RF interface circuit 1008 may include transceiver circuitry and a radio frequency front-end module (RFEM) that allows the UE 1000 to communicate with other devices via a radio access network. The RF interface circuit 1008 may include various elements arranged in a transmit path or a receive path. These elements may include switches, mixers, amplifiers, filters, synthesizer circuits, control circuits, etc.

[0109] In the receive path, the RFEM may receive a radiated signal from the air interface via the antenna 1024 and continue to filter and amplify the signal (using a low noise amplifier). The signal may be provided to the receiver of the transceiver, which down-converts the RF signal to a baseband signal that is provided to the baseband processor of the processor 1004.

[0110] In the transmit path, the transmitter of the transceiver up-converts the baseband signal received from the baseband processor and provides the RF signal to the RFEM. The RFEM may amplify the RF signal via a power amplifier before the signal is radiated across the air interface via the antenna 1024.

[0111] In various embodiments, the RF interface circuit 1008 may be configured to transmit / receive signals in a manner compatible with the NR access technology.

[0112] Antenna 1024 may include multiple antenna elements, each of which converts an electrical signal into a radio wave to travel through the air and converts the received radio wave into an electrical signal. These antenna elements may be arranged into one or more antenna panels. Antenna 1024 may have an antenna panel that is omnidirectional, directional, or a combination thereof to enable beamforming and multiple-input / multiple-output communication. Antenna 1024 may include a microstrip antenna, a printed antenna fabricated on the surface of one or more printed circuit boards, a patch antenna, a phased array antenna, etc. Antenna 1024 may have one or more panels that are designed for a specific frequency band including a frequency band in FR1 or FR2.

[0113] User interface circuit 1016 includes various input / output (I / O) devices that are designed to enable a user to interact with UE 1000. User interface 1016 includes input device circuitry and output device circuitry. Input device circuitry includes any physical or virtual component for accepting input, particularly including one or more physical or virtual buttons (e.g., a reset button), a physical keyboard, a keypad, a mouse, a touchpad, a touchscreen, a microphone, a scanner, a headset, etc. Output device circuitry includes any physical or virtual component for displaying information or otherwise communicating information such as sensor readings, actuator positions, or other similar information. Output device circuitry may include any number or combination of audio or visual displays, particularly including one or more simple visual outputs / indicators (e.g., binary state indicators such as light-emitting diodes (LEDs)) and multi-character visual outputs or more complex outputs such as a display device or a touchscreen (e.g., a liquid crystal display (LCD), an LED display, a quantum dot display, a projector, etc.), where the output of characters, graphics, multimedia objects, etc. is generated or produced by the operation of UE 1000.

[0114] Sensor 1020 may include a device, module, or subsystem aimed at detecting events or changes in its environment and sending information about the detected events (sensor data) to some other device, module, subsystem, etc. Examples of such sensors particularly include: an inertial measurement unit including an accelerometer; a gyroscope; or a magnetometer; a microelectromechanical system or a nanoelectromechanical system including: a three-axis accelerometer; a three-axis gyroscope; or a magnetometer; a liquid level sensor; a flow sensor; a temperature sensor (e.g., a thermistor); a pressure sensor; a barometric pressure sensor; a gravimeter; an altimeter; an image capture device (e.g., a camera or a lensless aperture); a light detection and ranging sensor; a proximity sensor (e.g., an infrared radiation detector, etc.); a depth sensor; an ambient light sensor; an ultrasonic transceiver; a microphone or other similar audio capture devices; and so on.

[0115] The drive circuit 1022 may include software elements and hardware elements for controlling specific devices embedded in, attached to, or otherwise communicatively coupled to the UE 1000. The drive circuit 1022 may include various drivers to allow other components to interact with or control various input / output (I / O) devices that may be present within or connected to the UE 1000. For example, the drive circuit 1022 may include: a display driver for controlling and allowing access to a display device, a touchscreen driver for controlling and allowing access to a touchscreen interface, a sensor driver for obtaining sensor readings from the sensor circuit 1020 and controlling and allowing access to the sensor circuit 1020, a driver for obtaining the actuator position of an electromechanical component or controlling and allowing access to an electromechanical component, a camera driver for controlling and allowing access to an embedded image capture device, and an audio driver for controlling and allowing access to one or more audio devices.

[0116] The PMIC 1024 may manage the power provided to various components of the UE 1000. Specifically, with respect to the processor 1004, the PMIC 1024 may control power selection, voltage scaling, battery charging, or DC-DC conversion.

[0117] In some embodiments, the PMIC 1024 may control or otherwise be part of various power saving mechanisms of the UE 1000. For example, if the platform UE is in the RRC_Connected state, in which the platform remains connected to the RAN node because it expects to receive traffic soon, then after a period of inactivity, the platform may enter a state called discontinuous reception mode (DRX). During this state, the UE 1000 may power down for short intervals, thus saving power. If there is no data traffic activity over an extended period of time, the UE 1000 may transition to the RRC_Idle state, in which the UE is disconnected from the network and does not perform operations such as channel quality feedback, handover, etc. The UE 1000 enters a very low power state and performs paging, in which the UE wakes up periodically again to listen for the network and then powers down again. The UE 1000 may not receive data in this state; to receive data, the platform must transition back to the RRC_Connected state. Additional power saving modes may render the device unable to use the network for periods of time (ranging from seconds to hours) beyond the paging interval. During this time, the device is completely unable to connect to the network and may be completely powered down. Any data sent during this time will incur a significant delay, and it is assumed that the delay is acceptable.

[0118] The battery 1028 can power the UE 1000, but in some examples, the UE 1000 can be installed in a fixed location and can have a power source coupled to the power grid. The battery 1028 can be a lithium-ion battery, a metal-air battery such as a zinc-air battery, an aluminum-air battery, a lithium-air battery, etc. In some specific implementations, such as in vehicle-based applications, the battery 1028 can be a typical lead-acid car battery.

[0119] Figure 11 A gNB 1100 according to some embodiments is illustrated. The gNB node 1100 may be similar to and substantially interchangeable with a base station (e.g., gNB 108), and / or components thereof may be included in a TRP.

[0120] gNB 1100 may include a processor 1104, an RF interface circuit 1108, a core network (CN) interface circuit 1112, and a memory / storage device circuit 1116.

[0121] Components of gNB 1100 may be coupled to various other components via one or more interconnects 1128.

[0122] The processor 1104, RF interface circuit 1108, memory / storage circuit 1116 (including communication protocol stack 1110), antenna 1124, and interconnect 1128 may be similar to those of reference Figure 9 and Figure 10 Like named elements are shown and described.

[0123] The CN interface circuitry 1112 may provide connectivity to a core network (e.g., a 5th Generation Core Network (5GC) using a 5GC compatible network interface protocol such as a Carrier Ethernet protocol or some other suitable protocol). Network connectivity may be provided to / from the gNB 1100 via optical fiber or wireless backhaul. The CN interface circuitry 1112 may include one or more dedicated processors or FPGAs for communicating using one or more of the aforementioned protocols. In some implementations, the CN interface circuitry 1112 may include multiple controllers for providing connectivity to other networks using the same or different protocols.

[0124] It is understood that the use of personally identifiable information should be subject to privacy policies and practices that are generally recognized to meet or exceed industry or government requirements for maintaining user privacy. Specifically, personally identifiable information data should be managed and processed to minimize the risk of unintentional or unauthorized access or use, and the nature of the authorized use should be clearly stated to users.

[0125] For one or more embodiments, at least one of the components shown in one or more of the foregoing figures may be configured to perform one or more of the operations, techniques, processes, or methods described in the Example section below. For example, the baseband circuitry described above in connection with one or more of the foregoing figures may be configured to operate in accordance with one or more of the following examples. As another example, circuitry associated with a UE, base station, network element, etc. described above in connection with one or more of the foregoing figures may be configured to operate in accordance with one or more of the embodiments described in the Embodiment section below.

[0126] Embodiment

[0127] In the following sections, additional exemplary embodiments are provided.

[0128] Embodiment 1 includes a method implemented by a user equipment (UE), the method including: generating capability information indicating that the UE supports six or more layers for physical downlink shared channel (PDSCH) reception, wherein a first subset of the six or more layers is associated with a first set of receive chains of the UE and a second subset of the six or more layers is associated with a second set of receive chains of the UE to support downlink multiple-input multiple-output (MIMO) operation; processing configuration information indicating a resource configuration for a reference signal, wherein the reference signal is one of a channel state information reference signal (CSI-RS) or a sounding reference signal (SRS); and performing at least one of the following: generating a channel state information (CSI) report that indicates a mapping of the six or more layers to two or more codewords such that a first codeword is mapped to the first subset of the six or more layers and a second codeword is mapped to the second subset of the six or more layers; or determining an SRS resource grouping based on a first number of transmit ports to be used by the UE for SRS transmission and a second number of receive ports to be used by the UE for PDSCH reception.

[0129] Embodiment 2 includes a method implemented by a base station, the method comprising: receiving, from a UE, capability information indicating that the UE supports six or more layers for physical downlink shared channel (PDSCH) reception, wherein a first subset of the six or more layers is associated with a first set of receive chains of the UE and a second subset of the six or more layers is associated with a second set of receive chains of the UE to support downlink multiple-input multiple-output (MIMO) operation; transmitting, to the UE, configuration information indicating a resource configuration for a reference signal, wherein the reference signal is one of a channel state information reference signal (CSI-RS) or a sounding reference signal (SRS); and performing at least one of the following: receiving, from the UE, a channel state information (CSI) report indicating a mapping of the six or more layers to two or more codewords such that a first codeword is mapped to the first subset of the six or more layers and a second codeword is mapped to the second subset of the six or more layers; or determining an SRS resource grouping based on a first number of transmit ports to be used by the UE for SRS transmission and a second number of receive ports to be used by the UE for PDSCH reception.

[0130] Embodiment 3 includes the method according to any one of the preceding embodiments, wherein the capability information includes an information element indicating that the UE supports six layers for the downlink MIMO operation.

[0131] Embodiment 4 includes the method according to any one of the preceding embodiments, wherein the configuration information indicates a maximum rank that the UE will use to generate the CSI report, wherein the maximum rank is indicated by a bitmap in a rank restriction information element or is indicated separately from the rank restriction information element.

[0132] Embodiment 5 includes the method according to any one of the preceding embodiments, wherein when it is determined that the configuration information indicates that the UE can have a maximum number of layers for the CSI report that is more than four layers or when it is determined that the UE reports more than four layers in the CSI report, the mapping is indicated in the CSI report.

[0133] Embodiment 6 includes the method according to any one of the preceding embodiments, wherein the mapping indicates that the first codeword is to be processed based on the first subset of the six or more layers and the second codeword is to be processed based on the second subset of the six or more layers.

[0134] Embodiment 7 includes the method according to any one of the preceding embodiments, wherein the CSI report includes a first part and a second part, wherein the first part has a fixed bit size and the second part has a variable bit size and indicates the mapping.

[0135] Example 8 includes the method according to Example 8, wherein the first part indicates a rank, and wherein the variable bit size is based on the rank.

[0136] Example 9 includes the method according to any one of the preceding Examples 1 to 6, wherein the CSI report includes a first part and a second part, wherein the first part has a fixed bit size and indicates the mapping.

[0137] Example 10 includes the method according to Example 9, wherein the bit width and interpretation of the mapping in the first part are based on at least one of the following: a first maximum rank indicated by the configuration information, a second maximum rank indicated by the capability information, or a third maximum possible rank.

[0138] Example 11 includes the method according to any one of the preceding examples, wherein the CSI report indicates the mapping by using a bitmap, wherein the bits of the bitmap correspond to layers, and the value of the bit indicates whether the layer is mapped to a first codeword or a second codeword.

[0139] Example 12 includes the method according to any one of the preceding Examples 1 to 10, wherein the CSI report indicates the mapping by using a plurality of bits, wherein the total number of the plurality of bits used is based on the number of layers associated with the CSI report.

[0140] Example 13 includes the method according to the example in any one of the preceding examples, wherein the SRS resource grouping indicates that the same SRS resource is associated with a plurality of groups, and each group in the plurality of groups corresponds to a different SRS port.

[0141] Example 14 includes the method according to any one of the preceding examples, wherein the SRS resource grouping includes a plurality of groups, and each group is associated with a different SRS resource.

[0142] Example 15 includes the method according to any one of the preceding examples, wherein the SRS resource grouping includes a plurality of groups, and each group is associated with a different set of SRS resources.

[0143] Example 16 includes the method according to any one of the preceding examples, wherein the first quantity is one and the second quantity is six, and wherein the SRS resource grouping indicates at least one of the following: a first plurality of three SRS resources are grouped together and a second plurality of three SRS resources are grouped together, or a first set of SRS resources including three SRS resources corresponds to a first group of three receiving ports and a second set of SRS resources including the other three SRS resources corresponds to a second group of three receiving ports.

[0144] Embodiment 17 includes the method according to any one of the foregoing Embodiments 1 to 15, wherein the first quantity is one and the second quantity is eight, and wherein the SRS resource grouping indicates at least one of the following: a first plurality of four SRS resources are grouped together and a second plurality of four SRS resources are grouped together, or a first SRS resource set including four SRS resources corresponds to a first group of four receiving ports and a second SRS resource set including the other four SRS resources corresponds to a second group of four receiving ports.

[0145] Embodiment 18 includes the method according to any one of the foregoing Embodiments 1 to 15, wherein the first quantity is two and the second quantity is eight, and wherein the SRS resource grouping indicates at least one of the following: a first plurality of two SRS resources are grouped together and a second plurality of two SRS resources are grouped together, or a first SRS resource set including two SRS resources corresponds to a first group of four receiving ports and a second SRS resource set including the other two SRS resources corresponds to a second group of four receiving ports.

[0146] Embodiment 19 includes the method according to any one of the foregoing Embodiments 1 to 15, wherein the first quantity is four and the second quantity is eight, and wherein the SRS resource grouping indicates at least one of the following: a first group of one SRS resource and a second group of SRS resources, or a first SRS resource set including one SRS corresponds to a first group of four receiving ports, and a second SRS resource set including another SRS resource corresponds to a second group of four receiving ports.

[0147] Embodiment 20 includes the method according to any one of the foregoing Embodiments 1 to 15, wherein the first quantity is eight and the second quantity is eight, and wherein the SRS resource grouping indicates that a first plurality of four SRS ports associated with the SRS resources are grouped together and a second plurality of four SRS ports also associated with the SRS resources are grouped together.

[0148] Embodiment 21 includes a user equipment (UE), the user equipment (UE) including: one or more processors; and one or more memories, the one or more memories storing instructions that, when executed by the one or more processors, configure the UE to perform the method according to any of the foregoing embodiments.

[0149] Embodiment 22 includes one or more computer-readable media storing instructions that, when executed on a user equipment (UE), cause the UE to perform operations including those operations of the method according to any of the foregoing embodiments.

[0150] Example 23 includes an apparatus that includes means for performing one or more elements of the method described in or associated with any one of the foregoing examples.

[0151] Example 24 includes one or more non-transitory computer-readable media that include instructions that, when executed by one or more processors of a device, cause the device to perform one or more elements of the method described in or associated with any one of the foregoing examples.

[0152] Example 25 includes an apparatus that includes logic, modules, or circuitry for performing one or more elements of the method described in or associated with any one of the foregoing examples.

[0153] Example 26 includes an apparatus that includes: one or more processors and one or more computer-readable media that include instructions that, when executed by the one or more processors, cause the one or more processors to perform one or more elements of the method described in or associated with any one of the foregoing examples.

[0154] Example 27 includes a system that includes means for performing one or more elements of the method described in or associated with any one of the foregoing examples.

[0155] Example 28 includes an apparatus that includes: processing circuitry for performing one or more elements of the method described in or associated with any one of the foregoing examples or any other method or process described herein; and interface circuitry coupled to the processing circuitry, the interface circuitry communicatively coupling the processing circuitry to one or more components of a computing platform.

[0156] Unless otherwise explicitly stated, any one of the above examples may be combined with any other example (or combination of examples). The foregoing description of one or more specific embodiments provides illustration and description, but is not intended to be exhaustive or to limit the scope of the embodiments to the precise forms disclosed. Modifications and variations are possible in light of the above teachings, or may be acquired from practice of various embodiments.

[0157] Although the above embodiments have been described in considerable detail, many variations and modifications will become apparent to those skilled in the art once the above disclosure is fully understood. It is intended that the following claims be interpreted to cover all such variations and modifications.

Claims

1. A device, comprising: A processing circuit, the processing circuit being configured to: determining capability information indicating support for six or more layers for physical downlink shared channel (PDSCH) reception, wherein a first subset of the six or more layers is associated with a first set of receive chains and a second subset of the six or more layers is associated with a second set of receive chains to support downlink multiple-input multiple-output (MIMO) operations; processing configuration information indicating a resource configuration for a reference signal, wherein the reference signal is one of a channel state information reference signal (CSI-RS) or a sounding reference signal (SRS); as well as Do at least one of the following: generating a channel state information (CSI) report indicating a mapping of the six or more layers to two or more codewords such that a first codeword is mapped to the first subset of the six or more layers and a second codeword is mapped to the second subset of the six or more layers, or SRS resource grouping is determined based on a first number of transmission ports to be used for SRS transmission and a second number of reception ports to be used for the PDSCH reception. 2 . The apparatus of claim 1 , wherein the capability information comprises an information element indicating support for six layers for the downlink MIMO operation.

3. The apparatus according to claim 1, wherein the configuration information indicates a maximum rank for generating the CSI report, wherein the maximum rank is indicated by a bitmap in a rank restriction information element or is indicated separately from the rank restriction information element. 4 . The apparatus according to claim 1 , wherein when it is determined that the configuration information indicates that the maximum number of layers that can be reported for CSI is more than four layers or when it is determined that more than four layers are reported in the CSI report, the mapping is indicated in the CSI report.

5. The apparatus of claim 1, wherein the mapping indicates that the first codeword is to be processed based on the first subset of the six or more layers, and the second codeword is to be processed based on the second subset of the six or more layers. 6 . The apparatus of claim 1 , wherein the CSI report comprises a first part and a second part, wherein the first part has a fixed bit size, wherein the second part has a variable bit size and indicates the mapping.

7. The apparatus of claim 6, wherein the first portion indicates a rank, and wherein the variable bit size is based on the rank.

8. The apparatus of claim 1, wherein the CSI report comprises a first part and a second part, wherein the first part has a fixed bit size and indicates the mapping.

9. The apparatus of claim 1, wherein the CSI report indicates the mapping by using a bitmap, wherein bits of the bitmap correspond to layers, and values ​​of the bits indicate whether the layer is mapped to the first codeword or the second codeword.

10. The apparatus of claim 1, wherein the CSI report indicates the mapping by using a plurality of bits, wherein a total number of the plurality of bits used is based on a number of layers associated with the CSI report.

11. One or more computer-readable storage media storing instructions that, when executed by one or more processors, cause the one or more processors to perform operations comprising: determining capability information indicating support for six or more layers for physical downlink shared channel (PDSCH) reception, wherein a first subset of the six or more layers is associated with a first set of receive chains and a second subset of the six or more layers is associated with a second set of receive chains to support downlink multiple-input multiple-output (MIMO) operations; processing configuration information indicating a resource configuration for a reference signal, wherein the reference signal is one of a channel state information reference signal (CSI-RS) or a sounding reference signal (SRS); as well as Do at least one of the following: generating a channel state information (CSI) report indicating a mapping of the six or more layers to two or more codewords such that a first codeword is mapped to the first subset of the six or more layers and a second codeword is mapped to the second subset of the six or more layers, or SRS resource grouping is determined based on a first number of transmission ports to be used for SRS transmission and a second number of reception ports to be used for the PDSCH reception.

12. The one or more computer-readable storage media of claim 11, wherein the SRS resource grouping indicates that the same SRS resource is associated with a plurality of groups, each of the plurality of groups corresponding to a different SRS port.

13. The one or more computer-readable storage media of claim 11, wherein the SRS resource grouping comprises a plurality of groups, each group being associated with a different SRS resource.

14. The one or more computer-readable storage media of claim 11, wherein the SRS resource grouping comprises a plurality of groups, each group being associated with a different set of SRS resources.

15. A method comprising: processing capability information received from a user equipment (UE) and indicating that the UE supports six or more layers for physical downlink shared channel (PDSCH) reception, wherein a first subset of the six or more layers is associated with a first set of receive chains of the UE and a second subset of the six or more layers is associated with a second set of receive chains of the UE to support downlink multiple-input multiple-output (MIMO) operations; generating configuration information indicating a resource configuration for a reference signal for sending to the UE, wherein the reference signal is one of a channel state information reference signal (CSI-RS) or a sounding reference signal (SRS); as well as Do at least one of the following: processing a channel state information (CSI) report received from the UE and indicating a mapping of the six or more layers to two or more codewords such that a first codeword is mapped to the first subset of the six or more layers and a second codeword is mapped to the second subset of the six or more layers, or SRS resource grouping is determined based on a first number of transmission ports to be used by the UE for SRS transmission and a second number of reception ports to be used by the UE for the PDSCH reception.

16. A method according to claim 15, wherein the first number is one and the second number is six, and wherein the SRS resource grouping indicates at least one of the following: a first plurality of three SRS resources are grouped together and a second plurality of three SRS resources are grouped together, or a first SRS resource set including three SRS resources corresponds to a first group of three receiving ports and a second SRS resource set including other three SRS resources corresponds to a second group of three receiving ports.

17. A method according to claim 15, wherein the first number is one and the second number is eight, and wherein the SRS resource grouping indicates at least one of the following: a first plurality of four SRS resources are grouped together and a second plurality of four SRS resources are grouped together, or a first SRS resource set including four SRS resources corresponds to a first group of four receiving ports and a second SRS resource set including other four SRS resources corresponds to a second group of four receiving ports.

18. The method of claim 15, wherein the first number is two and the second number is eight, and wherein the SRS resource grouping indicates at least one of the following: a first plurality of two SRS resources are grouped together and a second plurality of two SRS resources are grouped together, or a first SRS resource set including two SRS resources corresponds to a first group of four receiving ports and a second SRS resource set including the other two SRS resources corresponds to a second group of four receiving ports.

19. The method of claim 15, wherein the first number is four and the second number is eight, and wherein the SRS resource grouping indicates at least one of: a first group of one SRS resource and a second group of SRS resources, or a first SRS resource set including one SRS corresponds to a first group of four receiving ports and a second SRS resource set including another SRS resource corresponds to a second group of four receiving ports.

20. The method of claim 15, wherein the first number is eight and the second number is eight, and wherein the SRS resource grouping indicates that a first plurality of four SRS ports associated with SRS resources are grouped together and a second plurality of four SRS ports also associated with the SRS resources are grouped together.

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