Channel Compression of Channel Feedback Reports - Patent application

Abstract

Methods, systems, and devices for wireless communication are described. For example, a user equipment (UE) may receive one or more reference signals from a base station. In some examples, the UE may receive one or more reference signals over a channel for communication between the UE and the base station. The UE may measure a response of the channel based on the one or more reference signals received over the channel. In some examples, the UE may transmit a message indicating a set of channel coefficients. The set of channel coefficients may correspond to a two-dimensional (2D) model representing the response. In some examples, the 2D model may include a spatial model of the channel and a time domain response.

Description

[Technical field]

[0001] cross reference

[0001] This patent application claims the benefit of U.S. patent application Ser. No. 17 / 534,290 by BAR-OR TILLINGER et al., entitled "CHANNEL COMPRESSION FOR CHANNEL FEEDBACK REPORTING," filed on November 23, 2021, which is assigned to the assignee of this application and expressly incorporated by reference into this specification.

[0002] The following relates to wireless communications, including channel compression of channel feedback reports. [Background technology]

[0003]

[0003] Wireless communication systems are widely deployed to provide various types of communication content, such as voice, video, packet data, messaging, broadcasts, and the like. These systems may be capable of supporting communication with multiple users by sharing available system resources (e.g., time, frequency, and power). Examples of such multiple-access systems include fourth generation (4G) systems, such as Long Term Evolution (LTE) systems, LTE-Advanced (LTE-A) systems, or LTE-A Pro systems, and fifth generation (5G) systems, sometimes referred to as New Radio (NR) systems. These systems may employ techniques such as code division multiple access (CDMA), time division multiple access (TDMA), frequency division multiple access (FDMA), orthogonal FDMA (OFDMA), or discrete Fourier transform spread orthogonal frequency division multiplexing (DFT-S-OFDM).

[0004]

[0004] A wireless multiple-access communication system may include one or more base stations or one or more network access nodes, each simultaneously supporting communication for multiple communication devices, sometimes known as User Equipment (UE). In some multiple-access communication systems, the UE may perform channel estimation and report parameters associated with the estimated channel to the base station. The base station may use the reported parameters to improve the capacity of the channel through adaptive techniques such as channel precoding, interference mitigation, and signal rank determination. However, the parameters associated with the estimated channel may not capture all characteristics of the channel, and thus the channel knowledge acquired by the base station may be insufficient. Summary of the Invention

[0005]

[0005] The described techniques relate to improved methods, systems, devices, and apparatuses that support channel compression of channel feedback reports. In general, a device (e.g., a user equipment (UE)) may receive one or more reference signals from a base station. In some examples, the UE may receive one or more reference signals over a channel for communication between the UE and the base station. The UE may measure a response of the channel based on the one or more reference signals received over the channel. In some examples, the UE may transmit a message indicating a set of channel coefficients. The set of channel coefficients may correspond to a two-dimensional (2D) model that represents the response. In some examples, the 2D model may include a spatial model of the channel and a time domain response.

[0006] A method for wireless communication in a user equipment (UE) is described. The method may include receiving at least one reference signal from the base station over a communication channel for wireless communication between the UE and the base station, determining a response of the communication channel based on the at least one reference signal received over the communication channel, and transmitting a message to the base station indicating a set of channel coefficients corresponding to a two-dimensional model representing the response, the two-dimensional model including a spatial model and a time domain response of the communication channel.

[0007]

[0007] An apparatus for wireless communication in a UE is described. The apparatus may include a processor, a memory coupled to the processor, and instructions stored in the memory. The instructions may be executable by the processor to cause the apparatus to receive at least one reference signal from the base station over a communication channel for wireless communication between the UE and the base station, determine a response of the communication channel based on the at least one reference signal received over the communication channel, and transmit a message to the base station indicating a set of channel coefficients corresponding to a two-dimensional model representing the response, the two-dimensional model including a spatial model and a time domain response of the communication channel.

[0008] Another apparatus for wireless communication in a UE is described, which may include: means for receiving at least one reference signal from a base station over a communication channel for wireless communication between the UE and the base station, means for determining a response of the communication channel based on the at least one reference signal received over the communication channel, and means for transmitting a message to the base station indicative of a set of channel coefficients corresponding to a two-dimensional model representing the response, the two-dimensional model including a spatial model and a time domain response of the communication channel.

[0009] A non-transitory computer-readable medium storing code for wireless communication in a UE is described. The code may include instructions executable by a processor to receive at least one reference signal from a base station over a communication channel for wireless communication between the UE and the base station, determine a response of the communication channel based on the at least one reference signal received over the communication channel, and send a message to the base station indicating a set of channel coefficients corresponding to a two-dimensional model representing the response, the two-dimensional model including a spatial model and a time domain response of the communication channel.

[0010]

[0010] Some examples of the methods, apparatus, and non-transitory computer-readable media described in this specification may further include operations, features, means, or instructions for determining a frequency domain response of the communication channel as part of determining the response, and generating a time domain response based on the frequency domain response of the communication channel.

[0011]

[0011] Some examples of the methods, apparatus, and non-transitory computer-readable media described in this specification may further include operations, features, means, or instructions for generating a spatial model based on the time domain or frequency domain response of the communication channel.

[0012]

[0012] In some examples of the methods, apparatus, and non-transitory computer-readable media described herein, the two-dimensional model may be a Kronecker product of a matrix representation of the spatial model and a matrix representation of the time-domain response of the communication channel.

[0013]

[0013] Some examples of the methods, apparatus, and non-transitory computer-readable media described in this specification may further include operations, features, means, or instructions for generating a set of channel coefficients based on a minimum mean squared error solution between the determined response and the two-dimensional model.

[0014]

[0014] In some examples of the methods, apparatus, and non-transitory computer-readable media described herein, the set of channel coefficients includes a set of quantized coefficients.

[0015]

[0015] Some examples of the methods, apparatus, and non-transitory computer-readable media described in this specification may further include operations, features, means, or instructions for generating a two-dimensional model based on one or more antennas at the UE, one or more antennas at the base station, or both.

[0016]

[0016] In some examples of the methods, apparatus, and non-transitory computer-readable media described herein, transmitting a message may include an act, feature, means, or instruction of transmitting a set of bits indicating a set of channel coefficients to a base station via a control channel or a shared channel.

[0017]

[0017] Some examples of the methods, apparatus, and non-transitory computer-readable media described in this specification may further include an operation, feature, means, or instruction for sending an indication of a number of quantized bits for the message to a base station based on the mean squared error or signal-to-noise ratio of the communication channel.

[0018]

[0018] Some examples of the methods, apparatus, and non-transitory computer-readable media described herein may further include an operation, feature, means, or instruction to transmit a set of channel coefficients in a first slot and a set of differential channel coefficients in a second slot after the first slot, where each differential channel coefficient of the set of differential channel coefficients includes a channel coefficient difference relative to a respective channel coefficient of the set of channel coefficients.

[0019]

[0019] Some examples of the methods, apparatus, and non-transitory computer-readable media described in this specification may further include an operation, feature, means, or instruction for transmitting a second set of channel coefficients different from the set of channel coefficients in a third slot after the first slot, and the set of channel coefficients and the second set of channel coefficients may be transmitted according to the first period.

[0020]

[0020] Some examples of the methods, apparatus, and non-transitory computer-readable media described herein may further include an operation, feature, means, or instruction for transmitting, in a fourth slot after the second slot, a second set of differential channel coefficients, where each differential channel coefficient of the second set of differential channel coefficients includes a channel coefficient difference relative to a respective channel coefficient of the set of channel coefficients or a respective differential channel coefficient of the set of differential channel coefficients, and the set of differential channel coefficients and the second set of differential channel coefficients may be transmitted according to a second period different from the first period.

[0021]

[0021] Some examples of the methods, apparatus, and non-transitory computer-readable media described in this specification may further include an operation, feature, means, or instruction of receiving an instruction from a base station instructing the UE to enable transmission of the set of differential channel coefficients, and transmitting the set of differential channel coefficients may be based on receiving the instruction.

[0022]

[0022] Some examples of the methods, apparatus, and non-transitory computer-readable media described in this specification may further include an operation, feature, means, or instruction of receiving an instruction from a base station instructing the UE to use a differential encoding procedure based on the mobility of the UE or the time interval between the message indicating the set of channel coefficients and a previous message indicating the previous set of channel coefficients.

[0023]

[0023] Some examples of the methods, apparatus, and non-transitory computer-readable media described in this specification may further include an operation, feature, means, or instruction for receiving an indication of an ordering of the set of spatial domain basis functions from a base station and generating a spatial model based on the ordering of the set of spatial domain basis functions.

[0024]

[0024] In some examples of the methods, apparatus, and non-transitory computer-readable media described herein, the instructions include a configuration for a spatial model that includes a list of spatial domain basis functions, where the list of spatial domain basis functions corresponds to an ordering of the set of spatial domain basis functions.

[0025]

[0025] Some examples of the methods, apparatus, and non-transitory computer-readable media described herein may further include an operation, feature, means, or instruction for receiving an indication of an ordering of the set of time domain basis functions from a base station and generating a time domain response based on the ordering of the set of time domain basis functions.

[0026]

[0026] Some examples of the methods, apparatus, and non-transitory computer-readable media described in this specification may further include an operation, feature, means, or instruction for transmitting an indication of an ordering of the set of spatial domain basis functions, an ordering of the set of time domain basis functions, or both.

[0027]

[0027] Some examples of the methods, apparatus, and non-transitory computer-readable media described herein may further include operations, features, means, or instructions for determining a time domain response of the communication channel at a set of multiple timings for each of a set of multiple antenna port pairs as part of determining the response, selecting a set of time domain basis functions based on determining the time domain response of the communication channel at the set of multiple timings, and generating the time domain response based on the selected set of time domain basis functions.

[0028]

[0028] Some examples of the methods, apparatus, and non-transitory computer-readable media described herein may further include operations, features, means, or instructions for determining a cumulative energy of the time domain response across the set of multiple antenna port pairs for each timing of the set of multiple timings, and selecting a set of timings from the set of multiple timings based on determining the cumulative energy of the time domain response for each timing of the set of multiple timings, wherein selecting the set of time domain basis functions may be based on the selected set of timings.

[0029]

[0029] Some examples of the methods, apparatus, and non-transitory computer-readable media described in this specification may further include operations, features, means, or instructions for evaluating a mean squared error and a channel estimate of the determined response using a selected set of timings, and selecting a set of time-domain basis functions may be based on evaluating the mean squared error.

[0030]

[0030] Some examples of the methods, apparatus, and non-transitory computer-readable media described in this specification may further include an operation, feature, means, or instruction to receive a number of timing indications from a base station, and selecting a set of time-domain basis functions may be based on the indicated number of timings.

[0031]

[0031] Some examples of the methods, apparatus, and non-transitory computer-readable media described in this specification may further include an operation, feature, means, or instruction for transmitting an indication of some of the timings of the multiple timing sets to a base station.

[0032]

[0032] Some examples of the methods, apparatus, and non-transitory computer readable media described herein may further include operations, features, means, or instructions for receiving an indication of a set of antenna port pairs from a base station, determining a correlation between each antenna port pair in the set of antenna port pairs, which may be associated with a UE or a base station, as part of determining the response, selecting a set of spatial domain basis functions based on determining the correlation between each antenna port pair in the set of antenna port pairs, and generating a spatial model based on the selected set of spatial domain basis functions.

[0033]

[0033] Some examples of the methods, apparatus, and non-transitory computer-readable media described in this specification may further include an operation, feature, means, or instruction for selecting a set of spatial domain basis functions based on the lowest determined correlation for an antenna port pair of the set of antenna port pairs.

[0034]

[0034] Some examples of the methods, apparatus, and non-transitory computer-readable media described herein may further include an operation, feature, means, or instruction for evaluating a spatial autocorrelation matrix based on determining the correlation between each antenna port pair of the set of antenna port pairs, and selecting the set of spatial domain basis functions may be based on the spatial autocorrelation matrix.

[0035] A method for wireless communication in a base station is described, which may include transmitting at least one reference signal to a UE over a communication channel for wireless communication between the UE and the base station, and receiving a message from the UE indicating a set of channel coefficients corresponding to a two-dimensional model representing a response of the communication channel, the two-dimensional model including a spatial model and a time domain response of the communication channel.

[0036]

[0036] An apparatus for wireless communication in a base station is described. The apparatus may include a processor, a memory coupled to the processor, and instructions stored in the memory. The instructions may be executable by the processor to cause the apparatus to transmit at least one reference signal to the UE via a communication channel for wireless communication between the UE and the base station, and to receive from the UE a message indicating a set of channel coefficients corresponding to a two-dimensional model representing a response of the communication channel, the two-dimensional model including a spatial model and a time domain response of the communication channel.

[0037] Another apparatus for wireless communication in a base station is described, which may include means for transmitting at least one reference signal to a UE over a communication channel for wireless communication between the UE and the base station, and means for receiving from the UE a message indicating a set of channel coefficients corresponding to a two-dimensional model representing a response of the communication channel, the two-dimensional model including a spatial model and a time domain response of the communication channel.

[0038] A non-transitory computer-readable medium storing code for wireless communication in a base station is described, the code may include instructions executable by a processor to transmit at least one reference signal to a UE over a communication channel for wireless communication between the UE and the base station, and to receive from the UE a message indicating a set of channel coefficients corresponding to a two-dimensional model representing a response of the communication channel, the two-dimensional model including a spatial model and a time domain response of the communication channel.

[0039]

[0039] In some examples of the methods, apparatus, and non-transitory computer-readable media described herein, the two-dimensional model may be a Kronecker product of a matrix representation of the spatial model and a matrix representation of the time-domain response of the communication channel.

[0040]

[0040] In some examples of the methods, apparatus, and non-transitory computer-readable media described herein, the set of channel coefficients includes a set of quantized coefficients.

[0041]

[0041] In some examples of the methods, apparatus, and non-transitory computer-readable media described herein, receiving a message may include an act, feature, means, or instruction of receiving a set of bits from the UE via a control channel or a shared channel indicating a set of channel coefficients.

[0042]

[0042] Some examples of the methods, apparatus, and non-transitory computer-readable media described in this specification may further include an operation, feature, means, or instruction for receiving from the UE an indication of a number of quantization bits for the message based on a mean squared error or signal-to-noise ratio of the communication channel.

[0043]

[0043] Some examples of the methods, apparatus, and non-transitory computer-readable media described herein may further include an operation, feature, means, or instruction for receiving a set of channel coefficients in a first slot and receiving a set of differential channel coefficients in a second slot after the first slot, where each differential channel coefficient of the set of differential channel coefficients includes a channel coefficient difference relative to a respective channel coefficient of the set of channel coefficients.

[0044]

[0044] Some examples of the methods, apparatus, and non-transitory computer-readable media described herein may further include an operation, feature, means, or instruction for receiving a second set of channel coefficients different from the set of channel coefficients in a third slot after the first slot, and the set of channel coefficients and the second set of channel coefficients may be received according to the first period.

[0045]

[0045] Some examples of the methods, apparatus, and non-transitory computer-readable media described herein may further include an operation, feature, means, or instruction for receiving, in a fourth slot after the second slot, a second set of differential channel coefficients, where each differential channel coefficient of the second set of differential channel coefficients includes a channel coefficient difference relative to a respective channel coefficient of the set of channel coefficients or a respective differential channel coefficient of the set of differential channel coefficients, and the set of differential channel coefficients and the second set of differential channel coefficients may be transmitted according to a second period different from the first period.

[0046]

[0046] Some examples of the methods, apparatus, and non-transitory computer-readable media described in this specification may further include an operation, feature, means, or instruction of sending an instruction to the UE instructing the UE to enable transmission of the set of differential channel coefficients, and receiving the set of differential channel coefficients may be based on sending the instruction.

[0047]

[0047] Some examples of the methods, apparatus, and non-transitory computer-readable media described in this specification may further include an operation, feature, means, or instruction of sending an instruction to the UE instructing the UE to use a differential encoding procedure based on the mobility of the UE or the time interval between the message indicating the set of channel coefficients and a previous message indicating the previous set of channel coefficients.

[0048]

[0048] Some examples of the methods, apparatus, and non-transitory computer-readable media described in this specification may further include an operation, feature, means, or instruction for transmitting to a UE an indication of the ordering of the set of spatial domain basis functions for the two-dimensional model.

[0049]

[0049] In some examples of the methods, apparatus, and non-transitory computer-readable media described herein, the instructions include a configuration for a spatial model that includes a list of spatial domain basis functions, where the list of spatial domain basis functions corresponds to an ordering of the set of spatial domain basis functions.

[0050]

[0050] Some examples of the methods, apparatus, and non-transitory computer-readable media described in this specification may further include an operation, feature, means, or instruction for transmitting to a UE an indication of the ordering of the set of time-domain basis functions for the two-dimensional model.

[0051]

[0051] Some examples of the methods, apparatus, and non-transitory computer-readable media described in this specification may further include an operation, feature, means, or instruction for receiving instructions for ordering a set of spatial domain basis functions, ordering a set of time domain basis functions, or both, for a two-dimensional model.

[0052]

[0052] Some examples of the methods, apparatus, and non-transitory computer-readable media described in this specification may further include an operation, feature, means, or instruction for transmitting certain timing instructions for the two-dimensional model to the UE.

[0053]

[0053] Some examples of the methods, apparatus, and non-transitory computer-readable media described in this specification may further include an operation, feature, means, or instruction to receive from the UE an indication of some of the sets of timings for the two-dimensional model.

[0054]

[0054] Some examples of the methods, apparatus, and non-transitory computer-readable media described in this specification may further include an operation, feature, means, or instruction for transmitting to the UE an indication of a set of antenna port pairs, each antenna port pair being associated with a UE or a base station. [Brief description of the drawings]

[0055] [Figure 1]

[0055] Each illustrates an example of a wireless communication system supporting channel compression of channel feedback reports in accordance with an aspect of the present disclosure. [Diagram 2]Each illustrates an example of a wireless communication system that supports channel compression of channel feedback reports in accordance with an aspect of the present disclosure. [Diagram 3]

[0056] 1 illustrates an example of a channel compression procedure to support channel compression of channel feedback reports, according to an aspect of the present disclosure. [Figure 4A]

[0057] 11A-11C each illustrate an example of a performance response diagram supporting channel compression of channel feedback reports in accordance with an aspect of the present disclosure. [Figure 4B] 11A-11C each illustrate an example of a performance response diagram supporting channel compression of channel feedback reports in accordance with an aspect of the present disclosure. [Diagram 5]

[0058] 1 illustrates an example of a time domain channel response diagram supporting channel compression of channel feedback reports in accordance with an aspect of the present disclosure. [Figure 6A]

[0059] Each illustrates an example of a differential encoding scheme that supports channel compression of channel feedback reports in accordance with an aspect of the present disclosure. [Figure 6B] Each illustrates an example of a differential encoding scheme that supports channel compression of channel feedback reports in accordance with an aspect of the disclosure. [Figure 7]

[0060] 1 illustrates an example of a performance response diagram supporting channel compression of channel feedback reports in accordance with an aspect of the present disclosure. [Figure 8]

[0061] 1 illustrates an example of a process flow for supporting channel compression of channel feedback reports, according to an aspect of the disclosure. [Figure 9]

[0062] 1 illustrates a block diagram of a device that supports channel compression of channel feedback reports according to an aspect of the disclosure. [Figure 10] 1 illustrates a block diagram of a device that supports channel compression of channel feedback reports according to an aspect of the disclosure. [Figure 11]

[0063] 1 illustrates a block diagram of a communications manager supporting channel compression of channel feedback reports according to an aspect of the disclosure. [Figure 12]

[0064] 1 illustrates a diagram of a system including a device that supports channel compression of channel feedback reports in accordance with an aspect of the present disclosure. [Figure 13]

[0065] 1 illustrates a block diagram of a device that supports channel compression of channel feedback reports according to an aspect of the disclosure. [Figure 14] 1 illustrates a block diagram of a device that supports channel compression of channel feedback reports according to an aspect of the disclosure. [Figure 15]

[0066] 1 illustrates a block diagram of a communications manager supporting channel compression of channel feedback reports according to an aspect of the disclosure. [Figure 16]

[0067] 1 illustrates a diagram of a system including a device that supports channel compression of channel feedback reports in accordance with an aspect of the disclosure. [Figure 17]

[0068] 1 illustrates a flowchart illustrating a method for supporting channel compression of channel feedback reports according to an aspect of the disclosure. [Figure 18] 1 illustrates a flowchart illustrating a method for supporting channel compression of channel feedback reports according to an aspect of the disclosure. [Figure 19] 1 illustrates a flowchart illustrating a method for supporting channel compression of channel feedback reports according to an aspect of the disclosure. [Figure 20] 1 illustrates a flowchart illustrating a method for supporting channel compression of channel feedback reports according to an aspect of the disclosure. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0056]

[0069] A wireless multiple-access communication system may include several base stations or network access nodes, each simultaneously supporting communication for multiple communication devices, sometimes known as user equipments (UEs). For example, a wireless communication system may be configured to support multiple-input multiple-output (MIMO) in various frequency bands to enable increased throughput within the communication system. In some examples, MIMO communication may be performed via beamforming using multiple antennas at a transmitter (e.g., a base station or a UE) and multiple antennas at a receiver (e.g., a base station or a UE). In some cases, a UE and a base station may share information regarding the quality of a communication channel to improve signal reliability and efficiency for MIMO communication. For example, a communication system may support a format for reporting channel state feedback (CSF), in which a UE performs channel estimation and reports one or more parameters associated with the estimated communication channel to a base station. In some examples, the reported parameters may be referred to as channel state information (CSI), which may include a channel quality indicator (CQI), a precoding matrix indicator (PMI), or a rank indicator (RI), among others.

[0057]

[0070] In some examples, the base station may use the reported CSI to maximize the capacity of the communication channel through techniques (e.g., adaptation techniques) used to adapt the communication rate to the communication channel. Such adaptation techniques may include channel precoding, multi-user MIMO (MU-MIMO) scheduling, interference mitigation, and signal rank determination, among other examples. Although the CSI reported to the base station may include parameters associated with the estimated communication channel (e.g., a precoding matrix, a modulation and coding scheme (MCS), or a rank), the parameters may not capture all characteristics of the communication channel. That is, the reported CSI may not capture the entire response of the communication channel (e.g., a channel response), and thus the channel knowledge acquired by the base station may be insufficient. Thus, the efficiency of the adaptation techniques performed by the base station may be reduced. Furthermore, the overhead associated with CSI reporting may increase with the number of antenna ports used by a transmitting device (e.g., a base station). Thus, when a base station includes a large number of antennas, for example to support massive MIMO communication, the CSI may not be in a suitable format for reporting the CSF.

[0058]

[0071] Various aspects of the present disclosure relate to techniques for basis function selection for efficient CSF reporting. In general, the described techniques provide for reporting an estimated communication channel through channel compression. In some examples, a communication device may perform two-dimensional (2D) channel estimation using a time-frequency model (e.g., a time-domain response of the channel or a time-domain impulse response of the channel) and a time-spatial model (e.g., a spatial model representing the time-domain response of the channel across antenna ports at the transmitter and receiver) to obtain a set of channel coefficients representing an estimated communication channel. In some examples, the UE may compress the channel coefficients using quantization and entropy coding (e.g., lossless compression).

[0059]

[0072] The UE may indicate the set of coefficients to the base station. The base station may use the set of coefficients to obtain an estimated communication channel and determine parameters for adaptive techniques such as channel precoding, MU-MIMO scheduling, interference mitigation, and signal rank determination, among other examples. In some examples, the UE may obtain the set of channel coefficients using a joint (e.g., 2D) model expressed as a Kronecker product of a matrix representation of a spatial model and a matrix representation of a time-domain response of the communication channel. In some examples, the UE may indicate the set of coefficients obtained by finding a minimum mean square error (MMSE) solution to the joint model. That is, generation of the channel coefficients may be achieved by the UE finding an MMSE solution between a representation of the channel response using the 2D model and a measured channel response.

[0060]

[0073] In some examples, the time domain model (e.g., a time domain response of a communication channel or a time domain channel response) may include a set of time domain basis functions, each describing a time domain location of the time domain response of the channel. Additionally or alternatively, the spatial model may include one or more sets of spatial domain basis functions associated with spatial correlation between antennas at a base station (e.g., a transmitter) or between antennas at a UE (e.g., a receiver). That is, the spatial domain basis functions may relate to correlation between antennas at a base station or antennas at a UE, such that selecting a set of spatial domain basis functions may include selecting one or more eigenvectors (e.g., corresponding to the highest eigenvalues) of an autocorrelation matrix of the antennas at the base station or antennas at the UE. In some examples, the spatial domain basis functions may correspond to antennas at a base station or UE. For example, one set of spatial domain basis functions may relate to antennas at a base station and another set (e.g., a different set) of spatial domain basis functions may relate to antennas at a UE.

[0061]

[0074] In some examples, the UE may exploit channel sparsity to obtain time-domain and spatial-domain basis functions. For example, the UE may determine the time-domain basis functions based on the energy of the time-domain response of the channel at different time positions (e.g., delays or timings). In some examples, the UE may select some time delays (e.g., time-domain basis functions) for which the energy of the time-domain response is relatively high. In some other examples, the UE may iteratively evaluate different time delay combinations and select a time delay combination for which the expected mean square error (MSE) of the estimated channel is reduced.

[0062]

[0075] In some examples, the UE may determine the set of spatial domain basis functions by evaluating an autocorrelation matrix associated with a pair of antenna ports at the base station or a pair of antenna ports at the UE. For example, the UE may determine the autocorrelation matrix by measuring the correlation between one or more pairs of antenna ports (e.g., a pair of antenna ports at the UE or a pair of antenna ports at the base station) or by modeling the correlation between one or more pairs of antenna ports (e.g., at the UE or the base station) using a 2D topology of the antenna array at the UE and a 2D topology of the antenna array at the base station. The UE may determine the spatial domain basis functions by performing a singular value decomposition (SVD) on the autocorrelation matrix and selecting vectors (e.g., spatial domain basis functions) that have relatively large values ​​(e.g., eigenvalues). In some other examples, the UE may select the time domain basis functions and the spatial domain basis functions based on one or more instructions from the base station. For example, the base station may indicate the set of time domain basis functions and the spatial domain basis functions (e.g., in a given order) to the UE. The UE may select a subset of basis functions (e.g., according to an indicated ordering) for the time domain response and spatial model of the channel, respectively. In another example, the base station may indicate a list of configurations (e.g., sets) of time domain basis functions and spatial domain basis functions. The UE may select one or more sets of basis functions from the lists for the time domain response and spatial model, respectively. In some examples, the UE may transmit an indication of the selected time domain basis functions and spatial domain basis functions to the base station.

[0063]

[0076] In some examples, the UE may dynamically evaluate different combinations of channel compression parameters to determine a channel compression configuration that reduces an expected error (e.g., MSE). The channel compression parameters may include, among other examples, the number of time domain basis functions, the time domain position (e.g., the delay used to determine the time domain basis function), the number of spatial domain basis functions, the spatial domain basis function index (e.g., used to determine the spatial domain basis function), or the number of quantization bits (e.g., per channel coefficient). Additionally or alternatively, the base station may transmit one or more parameters to the UE to assist the UE in performing channel compression. For example, the base station may transmit one or more parameters for performing differential encoding, determining a channel compression configuration, or determining the time domain and spatial domain basis functions.

[0064]

[0077] Additionally or alternatively, the UE may use differential coding to increase the accuracy with which the set of coefficients represents the estimated channel (e.g., to further increase the tradeoff between accuracy and overhead). In some examples, using differential coding may increase the efficiency for transmitting reduced size messages to indicate changes in the channel (e.g., relatively small changes) when the channel estimate changes, compared to reporting one or more complete sets of coefficients representing the estimated channel. For example, the UE may use differential coding to determine changes in the values ​​of quantized channel coefficients between a first time slot and one or more other time slots that may occur after the first time slot. In some examples, the one or more other time slots (e.g., P slots) may be measured relative to an anchor (I slot), and in some other examples, the other one or more other time slots (P slots) may each be measured relative to a preceding time slot (e.g., P-1). For example, the first time slot may occur in the anchor slot (e.g., I) or a preceding time slot (e.g., P-1). The UE may encode the set of differential channel coefficients for transmission to the base station. In some cases, the set of differential channel coefficients may be transmitted to the base station at a periodicity lower than that at which the UE transmits the set of channel coefficients.

[0065]

[0078] In some examples, indicating a set of channel coefficients (e.g., or a set of differential channel coefficients) representing an estimated channel may increase the channel knowledge acquired by the base station and thus increase the efficiency of adaptation techniques performed by the base station. For example, the 2D model described herein may be used to compress channel responses across different antennas at a transmitter (e.g., a base station) or a receiver (e.g., a UE). The compression may take advantage of long-term spatial correlation (e.g., correlation between antennas at a base station or a UE) as well as the sparse nature of the channel in the time domain. Conventional techniques, such as those for PMI, may refer to a precoding matrix applied by a transmitter rather than a channel response. Furthermore, PMI may include or refer to coefficients per antenna port and therefore may not represent a channel response or a compressed channel response. The 2D model described herein represents a channel response (e.g., a compressed channel response) and may take into account long-term statistics, such as historical information or previous channel response information. PMI, on the other hand, does not take into account long-term statistics.

[0066]

[0079] Certain aspects of the subject matter described herein may be implemented to achieve one or more of the following potential advantages: Techniques employed by the described communications devices may provide benefits and enhancements to the operation of the communications devices, including increasing the efficiency of adaptation techniques performed by the communications devices. For example, the described techniques may support improvements and reliability of communications in wireless communications systems by increasing channel knowledge acquired by the communications devices. Furthermore, channel compression of channel feedback reports, as described herein, may reduce overhead, thereby improving latency and reliability. Thus, the described techniques may result in improved network operation and network operating efficiency, among other benefits.

[0067]

[0080] Aspects of the present disclosure are first described in the context of a wireless communication system. Aspects of the present disclosure are then described in the context of channel compression procedures, performance response diagrams, differential encoding schemes, and process flows. Aspects of the present disclosure are further illustrated by and described with reference to apparatus diagrams, system diagrams, and flow charts relating to channel compression of channel feedback reports.

[0068]

[0081] 1 illustrates an example of a wireless communication system 100 supporting channel compression of channel feedback reports according to aspects of the disclosure. The wireless communication system 100 may include one or more base stations 105, one or more UEs 115, and a core network 130. In some examples, the wireless communication system 100 may be a Long Term Evolution (LTE) network, a LTE-Advanced (LTE-A) network, a LTE-A Pro network, or a New Radio (NR) network. In some examples, the wireless communication system 100 may support enhanced broadband communications, ultra-reliable communications, low latency communications, communications with low-cost and low-complexity devices, or any combination thereof.

[0069]

[0082] The base stations 105 may be distributed throughout a geographic area to form the wireless communication system 100 and may be devices of different forms or with different capabilities. The base stations 105 and the UEs 115 may communicate wirelessly via one or more communication links 125. Each base station 105 may provide a coverage area 110 over which the UEs 115 and the base stations 105 may establish one or more communication links 125. The coverage area 110 may be an example of a geographic area over which the base stations 105 and the UEs 115 may support communication of signals according to one or more radio access technologies.

[0070]

[0083] The UEs 115 may be distributed throughout the coverage area 110 of the wireless communication system 100, and each UE 115 may be fixed or mobile or both at different times. The UEs 115 may be devices of different forms or with different capabilities. Some example UEs 115 are shown in FIG. 1. The UEs 115 described herein may be capable of communicating with various types of devices, such as other UEs 115, base stations 105, or network equipment (e.g., core network nodes, relay devices, integrated access and backhaul (IAB) nodes, or other network equipment) as shown in FIG. 1.

[0071]

[0084] The base stations 105 may communicate with the core network 130, or with each other, or both. For example, the base stations 105 may interface with the core network 130 through one or more backhaul links 120 (e.g., via an S1, N2, N3, or other interface). The base stations 105 may communicate with each other via the backhaul links 120 (e.g., via an X2, Xn, or other interface), either directly (e.g., between the base stations 105) or indirectly (e.g., via the core network 130), or both. In some examples, the backhaul links 120 may be or include one or more wireless links.

[0072]

[0085] One or more of the base stations 105 described herein may include or be referred to as a base transceiver station, wireless base station, access point, wireless transceiver, NodeB, eNodeB (eNB), next generation NodeB or giga-NodeB (any of which may be referred to as a gNB), Home NodeB, Home eNodeB, or other suitable terminology by one skilled in the art.

[0073]

[0086] The UE 115 may include or be referred to as a mobile device, a wireless device, a remote device, a handheld device, or a subscriber device, or any other suitable terminology, and a "device" may be referred to as a unit, a station, a terminal, or a client, among various examples. The UE 115 may also include or be referred to as a personal electronic device, such as a cellular phone, a personal digital assistant (PDA), a tablet computer, a laptop computer, or a personal computer. In some examples, the UE 115 may include or be referred to as a wireless local loop (WLL) station, an Internet of Things (IoT) device, an Internet of Everything (IoE) device, or a machine type communications (MTC) device, among various examples, which may be implemented in various items, such as an appliance, or a vehicle, a meter, among various examples.

[0074]

[0087] The UEs 115 described herein may be capable of communicating with various types of devices, such as other UEs 115, which may act as relays, as shown in FIG. 1, as well as base stations 105 and network equipment, including macro eNBs or gNBs, small cell eNBs or gNBs, or relay base stations, among various examples.

[0075]

[0088] The UE 115 and the base station 105 may wirelessly communicate with each other via one or more communication links 125 on one or more carriers. The term “carrier” may refer to a set of radio frequency spectrum resources having a defined physical layer structure to support the communication links 125. For example, a carrier used for the communication links 125 may include a portion (e.g., a bandwidth part (BWP)) of a radio frequency spectrum band that operates according to one or more physical layer channels for a given radio access technology (e.g., LTE, LTE-A, LTE-A Pro, NR). Each physical layer channel may carry collection signaling (e.g., synchronization signals, system information), control signaling to coordinate operation on the carrier, user data, or other signaling. The wireless communication system 100 may support communication with the UE 115 using carrier aggregation or multi-carrier operation. The UE 115 may be configured with multiple downlink component carriers and one or more uplink component carriers according to a carrier aggregation configuration. Carrier aggregation may be used with both frequency division duplexing (FDD) and time division duplexing (TDD) component carriers.

[0076]

[0089] A signal waveform transmitted on a carrier may be composed of multiple subcarriers (e.g., using a multi-carrier modulation (MCM) technique such as orthogonal frequency division multiplexing (OFDM) or discrete Fourier transform spread OFDM (DFT-S-OFDM)). In a system employing MCM techniques, a resource element may consist of one symbol period (e.g., the duration of one modulation symbol) and one subcarrier, where the symbol period and the subcarrier spacing are inversely related. The number of bits carried by each resource element may depend on the modulation scheme (e.g., the order of the modulation scheme, the coding rate of the modulation scheme, or both). Thus, the more resource elements the UE 115 receives and the higher the order of the modulation scheme, the higher the data rate may be for the UE 115. Wireless communication resources may refer to a combination of radio frequency spectrum resources, time resources, and spatial resources (e.g., spatial layers or beams), and the use of multiple spatial layers may further increase data rates or data integrity for communications with UE 115.

[0077]

[0090] The time interval for the base station 105 or the UE 115 is, for example, T s =1 / (Δf max N f )) seconds, where Δf max may represent the maximum supported subcarrier spacing, and N f may represent the maximum discrete Fourier transform (DFT) size supported. The communication resource time intervals may be organized according to radio frames, each having a specified duration (e.g., 10 milliseconds (ms)). Each radio frame may be identified by a system frame number (SFN) (e.g., ranging from 0 to 1023).

[0078]

[0091] Each frame may include multiple consecutively numbered subframes or slots, and each subframe or slot may have the same duration. In some examples, a frame may be divided (e.g., in the time domain) into subframes, and each subframe may be further divided into several slots. Alternatively, each frame may include a variable number of slots, and the number of slots may depend on the subcarrier spacing. Each slot may include several symbol periods (e.g., depending on the length of a cyclic prefix prepended to each symbol period). In some wireless communication systems, a slot may be further divided into multiple minislots that include one or more symbols. Excluding the cyclic prefix, each symbol period may include one or more (e.g., N f The duration of a symbol period may depend on the subcarrier spacing or the frequency band of operation.

[0079]

[0092] A subframe, slot, minislot, or symbol may be the smallest scheduling unit (e.g., in the time domain) of the wireless communications system 100 and may be referred to as a transmission time interval (TTI). In some examples, the TTI duration (e.g., the number of symbol periods in a TTI) may be variable. Additionally or alternatively, the smallest scheduling unit of the wireless communications system 100 may be dynamically selected (e.g., in a burst of shortened TTIs (sTTIs)).

[0080]

[0093] The physical channels may be multiplexed on the carriers according to various techniques. The physical control channels and the physical data channels may be multiplexed on the downlink carriers using, for example, one or more of a time division multiplexing (TDM), a frequency division multiplexing (FDM), or a hybrid TDM-FDM technique. A control region (e.g., a control resource set (CORESET)) for the physical control channels may be defined by a number of symbol periods and may extend across the system bandwidth of the carrier or a subset of the system bandwidth. One or more control regions (e.g., CORESETs) may be configured for a set of UEs 115. For example, one or more of the UEs 115 may monitor or search the control region for control information according to one or more search space sets, and each search space set may include one or more control channel candidates at one or more aggregation levels configured in a cascaded manner. The aggregation level for control channel candidates may refer to a number of control channel resources (e.g., control channel elements (CCEs)) associated with coded information for a control information format having a given payload size. The search space sets may include a common search space set configured for sending control information to multiple UEs 115 and a UE-specific search space set for sending control information to a specific UE 115.

[0081]

[0094] In some examples, the base stations 105 may be mobile and therefore may provide communication coverage to moving geographic coverage areas 110. In some examples, the different geographic coverage areas 110 associated with different technologies may overlap, but the different geographic coverage areas 110 may be supported by the same base station 105. In other examples, overlapping geographic coverage areas 110 associated with different technologies may be supported by different base stations 105. The wireless communication system 100 may include a heterogeneous network, for example, where different types of base stations 105 provide coverage to various geographic coverage areas 110 using the same or different radio access technologies.

[0082]

[0095] The wireless communication system 100 may be configured to support ultra-reliable or low latency communications, or various combinations thereof. For example, the wireless communication system 100 may be configured to support ultra-reliable low latency communications (URLLC). The UEs 115 may be designed to support ultra-reliable, low latency, or critical functionality. Ultra-reliable communications may include private or group communications and may be supported by one or more services such as push-to-talk, video, data, etc. Support for ultra-reliable, low latency functionality may include service prioritization, and such services may be used for public safety or general commercial applications. The terms ultra-reliable, low latency, and ultra-reliable low latency may be used interchangeably herein.

[0083]

[0096] In some examples, the UE 115 may also be able to communicate directly with other UEs 115 via a device-to-device (D2D) communication link 135 (e.g., using a peer-to-peer (P2P) protocol or a D2D protocol). One or more UEs 115 utilizing D2D communication may be within the geographic coverage area 110 of the base station 105. Other UEs 115 in such a group may be outside the geographic coverage area 110 of the base station 105 or may not be able to receive transmissions from the base station 105 in some cases. In some examples, a group of UEs 115 communicating via D2D communication may utilize a one-to-many (1:M) system, where each UE 115 transmits to every other UE 115 in the group. In some examples, the base station 105 facilitates scheduling of resources for D2D communication. In other cases, D2D communication is performed between UEs 115 without the involvement of the base station 105.

[0084]

[0097] The core network 130 may provide user authentication, access authorization, tracking, Internet Protocol (IP) connectivity, and other access, routing, or mobility functions. The core network 130 may be an evolved packet core (EPC) or a 5G core (5GC), which may include at least one control plane entity (e.g., a mobility management entity (MME), an access and mobility management function (AMF)) that manages access and mobility, and at least one user plane entity (e.g., a serving gateway (S-GW), a Packet Data Network (PDN) gateway (P-GW), or a user plane function (UPF)) that routes packets or interconnects to external networks. The control plane entity may manage non-access stratum (NAS) functions such as mobility, authentication, and bearer management for UEs 115 served by base stations 105 associated with the core network 130. User IP packets may be forwarded through a user plane entity, which may provide IP address allocation as well as other functions. The user plane entity may be connected to IP services 150 for one or more network operators. The IP services 150 may include access to the Internet, an intranet, IP Multimedia Subsystem (IMS), or packet-switched streaming services.

[0085]

[0098] Some of the network devices, such as the base stations 105, may include subcomponents, such as an access network entity 140, which may be an example of an access node controller (ANC). Each access network entity 140 may communicate with the UE 115 through one or more other access network transmitting entities 145, which may be referred to as radio heads, smart radio heads, or transmission / reception points (TRPs). Each access network transmitting entity 145 may include one or more antenna panels. In some configurations, various functions of each access network entity 140 or base station 105 may be distributed across various network devices (e.g., radio heads and ANCs) or integrated into a single network device (e.g., the base station 105).

[0086]

[0099] The wireless communication system 100 may operate using one or more frequency bands, typically in the range of 300 megahertz (MHz) to 300 gigahertz (GHz). The 300 MHz to 3 GHz region is commonly known as the ultra-high frequency (UHF) region or decimeter band because the wavelengths range from approximately 1 decimeter to 1 meter in length. Although UHF waves may be blocked or redirected by buildings and environmental features, the waves may penetrate structures well enough for a macrocell to serve UEs 115 located indoors. Transmission of UHF waves may be associated with smaller antennas and shorter distances (e.g., less than 100 kilometers) compared to transmissions using lower frequencies and longer waves in the shortwave (high frequency (HF)) or very high frequency (VHF) portions of the spectrum below 300 MHz.

[0087]

[0100] The wireless communication system 100 may utilize both licensed and unlicensed radio frequency spectrum bands. For example, the wireless communication system 100 may utilize License Assisted Access (LAA), LTE-Unlicensed (LTE-U) radio access technology, or NR technology in an unlicensed band, such as the 5 GHz industrial, scientific, and medical (ISM) band. When operating in an unlicensed radio frequency spectrum band, devices such as the base station 105 and the UE 115 may utilize carrier sensing for collision detection and avoidance. In some examples, operation in an unlicensed band may be based on a carrier aggregation configuration in conjunction with a component carrier operating in a licensed band (e.g., LAA). Operation in an unlicensed spectrum may include downlink transmissions, uplink transmissions, P2P transmissions, or D2D transmissions, among other examples.

[0088]

[0101] The base station 105 or UE 115 may be equipped with multiple antennas, which may be used to employ techniques such as transmit diversity, receive diversity, MIMO communications, or beamforming. The antennas of the base station 105 or UE 115 may be located in one or more antenna arrays or antenna panels that may support MIMO operations or transmit or receive beamforming. For example, one or more base station antennas or antenna arrays may be placed together in an antenna assembly, such as an antenna tower. In some examples, the antennas or antenna arrays associated with the base station 105 may be located in various geographic locations. The base station 105 may have an antenna array with several rows and columns of antenna ports that the base station 105 may use to support beamforming of communications with the UE 115. Similarly, the UE 115 may have one or more antenna arrays that may support various MIMO or beamforming operations. Additionally or alternatively, the antenna panel may support radio frequency beamforming for signals transmitted through the antenna ports.

[0089]

[0102] A base station 105 or a UE 115 may use MIMO communications to exploit multipath signal propagation and increase spectral efficiency by transmitting or receiving multiple signals via different spatial layers. Such techniques may be referred to as spatial multiplexing. Multiple signals may be transmitted by a transmitting device, for example, via different antennas or different combinations of antennas. Similarly, multiple signals may be received by a receiving device via different antennas or different combinations of antennas. Each of the multiple signals may be referred to as a separate spatial stream and may carry bits related to the same data stream (e.g., the same codeword) or different data streams (e.g., different codewords). Different spatial layers may be associated with different antenna ports used for channel measurement and reporting. MIMO techniques include single-user MIMO (SU-MIMO), in which multiple spatial layers are transmitted to the same receiving device, and MU-MIMO, in which multiple spatial layers are transmitted to multiple devices.

[0090]

[0103] Beamforming, sometimes referred to as spatial filtering, directional transmission, or directional reception, is a signal processing technique that may be used in a transmitting or receiving device (e.g., base station 105, UE 115) to shape or steer an antenna beam (e.g., transmit beam, receive beam) along a spatial path between the transmitting device and the receiving device. Beamforming may be achieved by combining signals communicated through multiple antenna elements of an antenna array such that some signals propagating in a particular orientation relative to the antenna array are subject to constructive interference, while other signals are subject to destructive interference. Adjustment of signals communicated through antenna elements may include a transmitting or receiving device applying an amplitude offset, a phase offset, or both to signals carried through an antenna element associated with the device. The adjustment associated with each of the antenna elements may be defined by a beamforming weight set associated with a particular orientation (e.g., relative to the transmitting or receiving device's antenna array, or to some other orientation).

[0091]

[0104] The base station 105 or the UE 115 may use beam sweeping techniques as part of a beamforming operation. For example, the base station 105 may use multiple antennas or antenna arrays (e.g., antenna panels) to perform a beamforming operation for directional communication with the UE 115. Some signals (e.g., synchronization signals, reference signals, beam selection signals, or other control signals) may be transmitted by the base station 105 multiple times in different directions. For example, the base station 105 may transmit signals according to different beamforming weight sets associated with different directions of transmission. The transmissions in different beam directions may be used (e.g., by a transmitting device such as the base station 105 or by a receiving device such as the UE 115) to identify beam directions for later transmission or reception by the base station 105.

[0092]

[0105] Some signals, such as data signals associated with a particular receiving device, may be transmitted by the base station 105 in a single beam direction (e.g., a direction associated with a receiving device, such as the UE 115). In some examples, the beam direction associated with a transmission along a single beam direction may be determined based on signals transmitted in one or more beam directions. For example, the UE 115 may receive one or more of the signals transmitted by the base station 105 in different directions and may report to the base station 105 an indication of the signal that the UE 115 received with the highest signal quality or possibly an acceptable signal quality.

[0093]

[0106] In some examples, transmission by a device (e.g., by the base station 105 or the UE 115) may be performed using multiple beam directions, and the device may use a combination of digital precoding or radio frequency beamforming to generate a combined beam for transmission (e.g., from the base station 105 to the UE 115). The UE 115 may report feedback indicating precoding weights for one or more beam directions, and the feedback may correspond to a configured number of beams across the system bandwidth or one or more subbands. The base station 105 may transmit a reference signal (e.g., cell-specific reference signal (CRS), channel state information reference signal (CSI-RS)) that may or may not be precoded. The UE 115 may provide feedback for beam selection, which may be PMI or codebook-based feedback (e.g., multi-panel type codebook, linear combination type codebook, port selection type codebook). Although these techniques are described with reference to signals transmitted by the base station 105 in one or more directions, the UE 115 may employ similar techniques to transmit a signal multiple times in different directions (e.g., to identify a beam direction for subsequent transmission or reception by the UE 115) or to transmit a signal in a single direction (e.g., to transmit data to a receiving device).

[0094]

[0107] A receiving device (e.g., UE 115) may attempt multiple receiving configurations (e.g., directional listening) when receiving various signals, such as synchronization signals, reference signals, beam selection signals, or other control signals, from the base station 105. For example, the receiving device may attempt multiple receiving directions by receiving via different antenna subarrays, by processing received signals according to different antenna subarrays, by receiving according to different receive beamforming weight sets (e.g., different directional listening weight sets) applied to signals received at multiple antenna elements of the antenna array, or by processing received signals according to different receive beamforming weight sets applied to signals received at multiple antenna elements of the antenna array, any of which may be referred to as "listening" with different receiving configurations or receiving directions. In some examples, the receiving device may use a single receiving configuration to receive along a single beam direction (e.g., when receiving a data signal). A single receiving configuration may be aligned to a beam direction determined based on listening through different receiving configuration directions (e.g., a beam direction determined to have the highest signal strength, highest signal to noise ratio (SNR), or possibly acceptable signal quality based on listening through multiple beam directions).

[0095]

[0108] The UE 115 and base station 105 may support retransmission of data to increase the likelihood of successful reception of the data. Hybrid automatic repeat request (HARQ) feedback is one technique for increasing the likelihood that data is correctly received on the communication link 125. HARQ may include a combination of error detection (e.g., using a cyclic redundancy check (CRC)), forward error correction (FEC), and retransmission (e.g., automatic repeat request (ARQ)). HARQ may improve throughput at the medium access control (MAC) layer in poor radio conditions (e.g., low signal-to-noise conditions). In some examples, a device may support same-slot HARQ feedback, in which the device may provide HARQ feedback in a particular slot for data received in a previous symbol in that slot. In other cases, the device may provide HARQ feedback in a subsequent slot or according to some other time interval.

[0096]

[0109] In some examples, the UE 115 may report an estimated communication channel through channel coefficient compression. For example, the UE 115 may perform 2D channel estimation and use a time-domain response and a spatial model to generate a set of channel coefficients representing the estimated channel. The set of channel coefficients may be quantized and encoded for transmission to the base station 105. In some examples, the time-domain response may be generated using time-domain basis functions that represent a time delay of the channel. The UE 115 may select a set of time-domain basis functions based on the energy of the time-domain response of the channel at different time delays. Additionally or alternatively, the spatial model may be based on the spatial-domain basis functions. The UE 115 may select a set of spatial domain basis functions based on a measured correlation between one or more pairs of antenna ports (e.g., a pair of antennas at the UE 115 or a pair of antennas at the base station 105) or based on modeling the correlation between one or more pairs of antenna ports (e.g., at the UE 115 or the base station 105) using a 2D topology of the antenna array at the UE 115 and a 2D topology of the antenna array at the base station 105.

[0097]

[0110] In some examples, the UE 115 may dynamically evaluate different combinations of channel coefficient compression, such as the number of basis functions or the number of quantization bits used per channel coefficient, to determine a channel compression configuration that reduces the prediction error. In some cases, the UE 115 may transmit an indication of one or more channel compression parameters to the base station. Additionally or alternatively, the base station 105 may indicate one or more channel compression parameters to the UE 115 to assist the UE 115 in generating a set of channel coefficients. Additionally or alternatively, to increase the accuracy with which the set of coefficients represents an estimated channel, the UE 115 may use differential coding to determine the change in values ​​of the quantized channel coefficients between different time slots. In some examples, indicating channel coefficients representing an estimated channel (e.g., rather than parameters associated with the estimated channel) may increase the channel knowledge acquired by the base station and thus increase the efficiency of adaptation techniques performed by the base station to increase the capacity of the channel.

[0098]

[0111] FIG. 2 illustrates an example of a wireless communication system 200 supporting channel compression of channel feedback reports according to aspects of the disclosure. In some examples, the wireless communication system 200 may implement aspects of the wireless communication system 100. For example, the wireless communication system 200 may include a base station 105-a and a UE 115-a, which may be examples of corresponding devices described with reference to FIG. 1. The base station 105-a and the UE 115-a may communicate within a geographic coverage area 110-a, which may be an example of the geographic coverage area 110 described with reference to FIG. 1. In some examples, the UE 115-a may communicate with the base station 105-a via a communication link 205 and a communication link 215. In the example of FIG. 2, the communication link 205 may be a downlink and the communication link 215 may be an uplink.

[0099]

[0112] In some examples, a transmitting device (e.g., base station 105-a) may obtain channel knowledge (e.g., knowledge of a communication channel) from a receiving device (e.g., UE 115-a), which may enable channel adaptation techniques at the transmitting device (e.g., base station 105-a). For example, a response of a communication channel (e.g., channel response) may refer to an impulse response function of the communication channel. That is, the channel may be characterized by a channel transfer function or a time-domain Fourier transform of the impulse response function of the communication channel. For example, a signal transmitted from a communication device may experience multipath propagation such that the transmitted signal may reach the receiving communication device by multiple (e.g., more than two) paths. Multipath propagation may result from atmospheric ducting, refraction, or reflection from objects in the surrounding area. In some examples, multipath propagation may result in interference and phase shifts (e.g., multipath interference or multipath distortion) of the transmitted signal, which may affect the signal before detection at the receiving communication device. That is, the signal at the time of reception may be altered relative to the signal at the time of transmission.

[0100]

[0113] In some examples, a received signal (e.g., a signal that has experienced multipath propagation through a communication channel) may be described by an impulse response function of the communication channel. The impulse response function may refer to the reaction (e.g., output) of a system in response to an external change (e.g., input). Thus, the impulse response function may take into account different impulses of a transmitted signal (e.g., a short input signal) that arrive at a receiver at different times (e.g., due to experiencing different paths). That is, the impulse response function of the communication channel may describe the behavior of a system (e.g., a communication channel) as a function of time. Thus, knowledge of the impulse response function of the communication channel (e.g., a response of the communication channel or a channel response) may aid channel adaptation techniques in a transmitting device.

[0101]

[0114] In some examples, channel adaptation techniques may be used by the base station 105-a to increase the capacity of the channel. For example, channel precoding, MU-MIMO scheduling, interference mitigation, etc., may be used by the transmitter to maximize system capacity. The base station 105-a may obtain channel knowledge in some examples via CSF reporting, and the UE 115-a performs channel estimation and reports one or more parameters (e.g., CSI parameters) associated with the estimated channel to the base station 105-a.

[0102]

[0115] However, in some examples, techniques for reporting channel knowledge to the base station 105-a may be insufficient. For example, using an uplink control channel (e.g., physical uplink control channel (PUCCH)) to report channel status (e.g., CSI parameters) may be inefficient in terms of overhead and accuracy. In some examples, the inefficiency in terms of overhead and accuracy may increase (e.g., may be more pronounced) with an increase in the number of antenna ports at the base station 105-a (e.g., for massive MIMO communication). For example, if the number of antenna ports used for transmission at the base station 105-a increases, the information transmitted over a given channel may increase (i.e., the communication channel may become richer), and thus the overhead used for CSF reporting of the channel may also increase. Thus, techniques (e.g., solutions) for reporting CSI parameters may not be suitable to capture additional or all channel characteristics and may therefore be a limited or inaccurate representation of the channel. Furthermore, techniques for reporting CSI parameters may not be well suited for massive MIMO communications, for example, when the reported CSI scales with the number of ports (e.g., antenna ports) at the transmitter, and may thus degrade system performance due to increased latency, inefficient use of network resources, etc.

[0103]

[0116] In some other examples, rather than reporting CSI parameters associated with the estimated channel, the UE 115-a may report the estimated channel itself through channel compression. For example, the UE 115-a may utilize techniques for efficient channel representation to balance the overhead used to report channel knowledge and the accuracy with which the channel is represented. In some examples, an efficient (e.g., compressed) channel representation may be used as a CSF format to achieve a desired overhead-accuracy tradeoff, as well as to enable a mechanism for adjusting the overhead-accuracy tradeoff using, for example, one or more parameters. In other words, a compressed representation of the channel response may be used as a basis for CSF reporting, e.g., with respect to overhead-accuracy tradeoff, allowing a mechanism to adjust such tradeoff according to system parameters. In some cases, a compressed representation of the channel response may be achieved using a 2D decomposition (e.g., a model) of the channel response. In some examples, using such a representation of the channel response may improve CSF reporting efficiency and enable channel adaptation techniques at the transmitting device (e.g., base station 105-a) that may use more accurate channel knowledge, increasing system capacity of the channel.

[0104]

[0117] As an illustrative example, the UE 115-a may receive one or more reference signals (e.g., reference signal 210) from the base station 105-a via the communication link 205. In some examples, the reference signal 210 may be transmitted over a channel for communication between the UE 115-a and the base station 105-a. The UE 115-a may measure a channel response of the channel based on the reference signal 210. In some examples, as part of measuring the channel response, the UE 115-a may measure a frequency domain response of the channel and generate a time domain response of the channel. The time domain response of the channel may be evaluated from the frequency domain response of the channel. Additionally or alternatively, the UE 115-a may generate a spatial model based on the time domain response of the channel or the frequency domain response of the channel. For example, the spatial model may be generated by evaluating the spatial behavior of the time domain response of the channel or the frequency domain channel response of the channel. That is, the UE 115-a may calculate a correlation between time-domain responses (e.g., or frequency-domain responses) of the channel from different antennas at the base station 105-a and determine a spatial model (e.g., a set of spatial-domain basis functions) based on the calculated correlation. In some examples, the UE 115-a may transmit a message 220 to the base station 105-a over the communication link 215. In some examples, the message 220 may indicate a set of channel coefficients corresponding to a 2D model representing the channel response. In some examples, the 2D model may include the time-domain response and the spatial model of the channel.

[0105]

[0118] 3 illustrates an example of a channel compression procedure 300 that supports channel compression of channel feedback reports in accordance with aspects of the present disclosure. In some examples, the channel compression procedure 300 may include aspects of the wireless communication systems 100 and 200 described with respect to Figures 1 and 2, respectively. For example, the channel compression procedure 300 may be implemented by a UE 115, which may be an example of a corresponding device described with reference to Figures 1 and 2.

[0106]

[0119] In some examples, a compact representation of the channel response may take advantage of the sparse nature (e.g., sparsity) of the communication channel in the spatial and time domains. For example, in the spatial domain, correlation between antenna ports at a transmitting device (e.g., a base station) or between antenna ports at a receiving device (e.g., a UE) may enable an accurate representation of the channel while using one or more eigenvectors of an autocorrelation matrix (e.g., a small number of eigenvectors compared to the number of antenna ports). In some examples, the spatial domain basis functions may be the eigenvectors of the autocorrelation matrix. In other words, antennas at the base station and the UE may be correlated such that a channel experienced by a first antenna may be correlated with a channel experienced by a second antenna located near the first antenna. Thus, collocated antennas may be correlated, and such antenna correlation may be exploited for channel compression. Additionally or alternatively, the channel between one transmitting antenna (e.g., an antenna at a base station) and a receiving antenna (e.g., an antenna at a UE) may also be sparse in the time domain. In some examples, the sparsity of the channel in the time domain (e.g., the sparsity of the time domain taps) may enable an accurate representation of the channel response using one or more time domain taps (e.g., time delays). In some examples, the time delays may be used as time domain basis functions of a time-frequency model (e.g., the time domain response of the channel).

[0107]

[0120] For example, as shown by FIG. 3, spatial domain basis functions 305 and time domain basis functions 310 may be combined (e.g., at 320 and 315, respectively) to generate a 2D (e.g., time and space) model (e.g., a compact representation of the channel response) that represents the channel response. In some examples, the 2D model may be used in channel compression 325, which may include 2D channel estimation 330, quantization 340, and encoding 350. For example, the 2D channel estimation 330 may be used to obtain a set of channel coefficients corresponding to the 2D model. Additionally or alternatively, quantization 340 and encoding 350 (e.g., entropy coding) of the channel coefficients may enable further compression of information (e.g., payload) reported to the base station. For example, the channel coefficients may be further compressed using quantization 340 and encoding 350 (e.g., at 335 and 345, respectively) and transmitted to the base station at 355.

[0108]

[0121] 4A and 4B each illustrate an example of a performance response diagram 400 supporting channel compression of channel feedback reports in accordance with aspects of the disclosure. In some examples, the performance response diagrams 400 (e.g., performance response diagrams 400-a and 400-b) may implement or be implemented by aspects of the wireless communications systems 100 and 200. For example, the performance response diagrams 400 may be associated with communications between a base station and a UE, which may be examples of corresponding devices described with reference to FIGS. 1 and 2.

[0109]

[0122] As shown in the example of FIG. 4A, the accuracy with which a channel estimation report (e.g., a set of channel coefficients indicated to a base station) represents an estimated channel may depend on the number of bits (e.g., the average number of bits per coefficient) used to represent the estimated channel. For example, performance response diagram 400-a shows the normalized mean square error (NMSE) (e.g., the error between the compressed channel response and the measured channel response) plotted as a function of bits, with each performance response (e.g., curve) representing a different technique for generating a set of spatial domain basis functions. In other words, performance response diagram 400-a shows the performance of different tradeoffs, for example, between signaling overhead in bits and accuracy of the channel estimation report. In the example of FIG. 4A, the performance shown in performance response diagram 400-a may be based on a 20 MHz channel bandwidth, 32 antenna ports at the transmitter (e.g., a base station), one antenna port at the receiver (e.g., a UE), and a UE speed of 3 kilometers per hour (kmph). However, different tradeoffs may be achieved using a different number of time domain basis functions, a different number of spatial domain basis functions, or a different number of quantization bits (eg, bits for quantization).

[0110]

[0123] In some examples, the performance responses (e.g., performance response 425-a, performance response 420-a, performance response 415-a, and performance response 410-a) may indicate that the NMSE of the compressed channel response (e.g., obtained from the MMSE solution of the 2D model) decreases as the number of bits used to represent the channel (e.g., the average number of bits used per coefficient) increases. In some examples, performance response 425-a may be achieved if the set of spatial domain basis functions is predefined (e.g., fixed), performance response 420-a may be achieved if the set of basis functions is updated (e.g., calculated using SVD) every 60 slots, performance response 415-a may be achieved if the spatial domain basis functions are updated (e.g., calculated using SVD) every 20 slots, and performance response 410-a may be achieved if the set of basis functions is updated instantaneously (e.g., performance response 410-a may correspond to the criteria for performance response 415-a, performance response 420-a, and performance response 425-a). In some examples, performance response diagram 400-a may show improvements (e.g., with respect to both signaling overhead and accuracy of channel response) achieved by the channel compression techniques described herein, for example, as compared to CSF ​​mechanisms that rely on CSI parameters. In some cases, the channel compression techniques described herein may have relatively low complexity at both the transmitter side (e.g., at a base station) and the receiver side (e.g., at a UE). Additionally or alternatively, the memory utilized may also be relatively small due to, for example, a reduced number of basis functions (e.g., less than 16) in the spatial or time domain (e.g., impulse response domain).

[0111]

[0124] In some examples, the speed of a receiving device (e.g., a UE) may affect how the accuracy of the set of channel coefficients depends on the spatial domain basis functions used to generate the set of channel coefficients. For example, the performance shown in performance response diagram 400-b may be based on a 20 MHz channel bandwidth, 32 antenna ports at the transmitter (e.g., a base station), 1 antenna port at the receiver (e.g., a UE), and a UE speed of 120 kmph. In some examples, performance response 425-b may be achieved if the set of spatial domain basis functions is predefined (e.g., fixed), performance response 420-b may be achieved if the set of basis functions is updated every 60 slots, performance response 415-b may be achieved if the set of basis functions is updated every 20 slots, and performance response 410-b may be achieved if the set of basis functions is updated instantaneously. In some cases, the performance responses of the set of channel coefficients (e.g., performance response 425-b, performance response 420-b, and performance response 415-b) may be less dependent on the set of spatial domain basis functions (e.g., the rate at which the spatial domain basis functions may be updated) compared to the performance responses (e.g., performance response 425-a, performance response 420-a, and performance response 415-a) shown in the example of FIG. 4A, which may be based on a UE speed of, for example, 3 kmph.

[0112]

[0125] In some examples, the average number of bits per message (e.g., the resulting compressed channel bits) is Z × M × B T ×B R where Z may represent the average number of bits per coefficient, M may represent the number of time-domain positions (e.g., time-domain basis functions), and B T may represent the number of spatial domain basis functions for determining (e.g., generating) a spatial model of a transmitting device (e.g., a base station), and B Rmay represent the number of spatial domain basis functions for determining (e.g., generating) a spatial model of a receiving device (e.g., UE). For example, the average number of bits per coefficient (e.g., Z) after quantization and encoding (e.g., entropy coding) may be communicated to the base station periodically or aperiodically (e.g., using a physical downlink control channel (PDCCH) or a physical uplink shared channel (PUSCH)). For example, the average number of bits per coefficient may be communicated according to scheduling by the base station (e.g., as may be performed according to one or more CSF mechanisms). Additionally or alternatively, the NMSE of the compressed channel response (e.g., obtained from an MMSE solution of the 2D model) may be communicated to the base station periodically or aperiodically (e.g., per CSF report).

[0113]

[0126] Additionally or alternatively, the number of bits used for quantization (e.g., the number of bits per real or imaginary component of the channel coefficient) may be adaptively selected (e.g., according to a parameter associated with the overhead-accuracy tradeoff) and communicated periodically or aperiodically. In some examples, the base station may indicate a desired number of bits for quantization to the UE. Additionally or alternatively, the base station may indicate a desired precision of the report (e.g., a desired NMSE or MSE of a set of channel coefficients) to the UE, and the UE may select a number of bits (e.g., for quantization) accordingly. For example, to transmit coefficients (which may represent, e.g., a compressed channel response) to the base station, the UE may convert the coefficients to a binary representation such that each coefficient component (e.g., real or imaginary) may be represented using a number (e.g., Z / 2) of bits. In some examples, the UE may increase the number of bits (Z) to increase the precision of the representation of the channel (e.g., the quantization error is reduced). In such examples, the message payload may also be increased. Therefore, a trade-off between accuracy and reduced reporting overhead can be achieved by adjusting the number of bits used for quantization.

[0114]

[0127] In some examples, the tradeoff between accuracy and overhead may be determined with respect to the channel condition. For example, if the SNR is relatively low, the accuracy of the CSF may also be low, and the UE may select (e.g., or may be instructed by the base station) to use fewer bits per coefficient. The UE may select the number of bits such that the quantization noise of the coefficients may not reduce (e.g., limit) the performance. For example, the number of bits may be determined such that the quantization noise may be lower for a given coefficient than the thermal noise. In another example (e.g., when the number of bits per coefficient is set to a certain value), the number of bits per coefficient may be adapted together with other parameters (e.g., the number of basis functions) to increase the accuracy of the compressed channel.

[0115]

[0128] In some examples, the UE may signal the selected number of bits for quantization to the base station. Additionally or alternatively, the UE may determine the number of bits for quantization with respect to the experienced MSE of the channel or with respect to the experienced SNR. In some examples, the UE may signal the selected number of bits for quantization to the base station. Additionally or alternatively, the UE may utilize a dictionary for compression of the coefficients, for example, using an entropy encoder. In some examples, the determination of the entropy encoder dictionary (e.g., dictionary symbols) may be performed to reduce an average message length (e.g., indicating a set of channel coefficients). Additionally or alternatively, the entropy encoder dictionary symbols may be predefined or communicated from the base station to the UE periodically or aperiodically. In some other examples, the UE may determine the entropy encoder dictionary using statistics of a previous transmission and indicate the determined entropy encoder dictionary to the base station. In other examples, the base station may determine the entropy encoder dictionary to be used (e.g., by the UE) and indicate the determined entropy encoder dictionary to the UE. In some cases, the base station may indicate the determined entropy encoder dictionary to the UE along with (eg, together with) other UEs to reduce complexity associated with operations at the base station.

[0116]

[0129] 5 illustrates an example of a time domain channel response diagram 500 supporting channel compression of channel feedback reports in accordance with aspects of the disclosure. In some examples, the time domain channel response diagram 500 may implement or be implemented by aspects of the wireless communications systems 100 and 200. For example, the time domain channel response diagram 500 may be associated with communications between a base station and a UE, which may be examples of corresponding devices described with reference to FIGS. 1 and 2.

[0117]

[0130] In some examples, the set of channel coefficients may be generated using a 2D (e.g., time-space) model that includes a spatial model and a time domain response of the channel. For example, the spatial model may be generated from spatial domain basis functions, and the time domain response of the channel may be generated based on the time domain basis functions. In some examples, the spatial domain basis functions and the time domain basis functions may be examples of corresponding basis functions described with reference to FIG. 3. For example, the spatial domain basis functions may reflect correlation between antenna ports at a transmitting device (e.g., a base station) or between antenna port pairs at a receiving device (e.g., a UE), and the time domain basis functions may reflect the time domain location of the channel response.

[0118]

[0131] In some examples, the time-domain response of the channel (e.g., a time-frequency model) may be represented by a time-domain transform of the frequency-domain response of the channel. In other words, the time-domain response of the channel may be evaluated from the frequency response of the channel. For example, the time-domain response of the channel may correspond to a Fourier transform of the measured frequency-domain response of the channel for each antenna port at the UE. That is, the frequency-domain response of the channel may be measured and transformed into a (e.g., sparse) time-domain response via a Fourier transform. For example, the time-domain response of the channel may be represented by the following equation:

[0119]

number

[0120] where

[0121]

number

[0122] is the frequency domain response (e.g., where

[0123]

number

[0124] may represent, where i ranges from 0 to Np-1, a vector containing a number (N) of frequency-domain coefficients of the channel measured at the (i-th) antenna port,

[0125]

number

[0126] is the time domain response (e.g., where

[0127]

number

[0128] may represent the time domain coefficients (e.g., the Fourier transform of the frequency domain response) of some (M) of the channels, and n may represent noise. c may represent a set of time-domain (e.g., impulse response domain) basis functions (e.g., where F c is a matrix with some (N) rows and some (M) columns), which may possibly be a sparse Fourier matrix truncated to some (N) selected time-domain basis function rows, each with some number (M) of coefficients.

[0129]

[0132] In some instances, the time-domain basis functions (e.g., F c) may be determined based on the energy of the time domain response of the channel at different time positions (e.g., delays). For example, the UE may select several (M) time delays (e.g., time domain basis functions) for which the energy of the time domain response is relatively high, e.g., as compared to the time domain response at other time delays. In some cases, the UE may determine (e.g., find) the time domain response of a communication channel at multiple transmit antenna ports (e.g., each antenna port used for uplink communication to a base station) and multiple receive antenna ports (e.g., each antenna port used for downlink communication from a base station) and accumulate the energy (e.g., across each of the transmit antenna ports and receive antenna ports) for several time delays (e.g., M time delays). For example, as shown in the example of FIG. 5, a time domain channel response diagram 500 illustrates a normalized time domain response of a communication channel (e.g., time domain channel response) at various time delays (e.g., τ0, τ1, τ2, τ3, τ4). In some cases, the UE may select the top M time delays (e.g., positions) as the time domain basis functions. As a specific example, if M is equal to 3, the time-domain positions may include τ0, τ1, and τ3.

[0130]

[0133] In some other examples, the UE may use an iterative approach (e.g., matching pursuit) to find the M time locations. For example, the UE may iteratively evaluate different time delay combinations and select a combination of time delays that reduces the expected mean square error (MSE) of the estimated channel. In some examples, during each iteration (e.g., in each round), the UE may loop over a configured or predefined number (m) of available time locations (e.g., τ0, τ1, τ2, τ3, τ4, where m is equal to 5) and evaluate, for example, the expected MSE if each of the available time locations is added to the subset of time locations. The UE may use the expected MSE to determine the time locations to be added (e.g., selected) during each iteration (e.g., round), and continue the iterations, for example, until a desired number (M) of locations are selected. In some examples, the UE may also perform a refinement phase. For example, the UE may loop over the M selected time positions and, during each iteration, remove one time position (e.g., from a set of M time positions) and search for another (e.g., not yet selected) time position among the number of available time positions (m) such that the MSE is improved. In some cases, if the MSE is (e.g., actually is) improved at the other time position, the UE may replace the removed time position with the other time position.

[0131]

[0134] In some examples, the UE may indicate to the base station the time positions selected as the time domain basis functions. In some examples, the indication may be direct or different (e.g., the indication may correspond to a difference from a previous state). In some examples, the base station may signal the number of time positions (M) to be used to the UE. In some other examples, the UE may report the number of time positions (M) to the base station. Furthermore, the base station may signal the time domain granularity to be used (e.g., to determine the time domain basis functions) to the UE or the UE may report the time domain granularity to the base station. Additionally or alternatively, the base station may signal a desired (e.g., target) accuracy of the report (e.g., a desired MSE of the compressed channel response), and the UE may determine a number of time positions or time domain granularity based on the desired MSE. In some examples, the UE may report the number of time positions or time domain granularity to the base station. In some examples, the number of time positions or time domain granularity may be used by the base station to reconstruct the time domain response of the channel. Additionally or alternatively, the base station may indicate a codebook of time-domain basis functions to the UE. In such an example, the UE may select a set of time-domain basis functions from the indicated codebook. Additionally or alternatively, the UE may report an index of the selected time-domain basis function in the codebook to the base station.

[0132]

[0135] In some cases, the UE may signal periodically updated basis functions (e.g., time domain basis functions or spatial domain basis functions), e.g., the update interval is based on a predefined value determined by both the base station and the UE (e.g., separately), a predefined value selected by the UE based on the UE's mobility state, the UE's velocity, or a value configured by the base station (e.g., via a radio resource control (RRC) message). In such cases, each indication may have a specific periodicity. In some other cases, the basis functions may be updated aperiodically, e.g., the UE or the base station may request aperiodic update of the basis vectors based on a change in communication bandwidth, or a reduced target accuracy of reporting, or a reduced MSE (e.g., a drop in the measured MSE). In such cases, each indication may be communicated using a downlink control information (DCI), MAC-CE, or RRC message.

[0133]

[0136] In some examples, the spatial model (e.g., a time-spatial model) may be evaluated using the time-domain response of the channel or the frequency-domain response of the channel. For example, the spatial model may be generated based on the spatial behavior of the time-domain response of the channel or the frequency-domain response of the channel. In some examples, the spatial model may correspond to (e.g., involve) each time-domain delay (e.g., tap) across space represented as a linear combination of spatial-domain basis functions. In some examples, the spatial model may be represented by the following equation:

[0134]

number

[0135] where

[0136]

number

[0137] may represent the time-domain response (e.g., time-domain taps) of the channel measured at the antenna port of the (i-th) UE (e.g., where i ranges from 0 to Np-1), c j [m] may represent the spatio-temporal response of the estimated communication channel (e.g., where j ranges from 0 to Br-1). Additionally or alternatively, each matrix U i,j may represent spatial-domain basis functions. Thus, each time-domain response across the antennas (e.g., spatial)

[0138] [Number]

[0139] can be represented using a few basis functions (e.g., Br) that are fewer than the number of frequency-domain coefficients (e.g., Br < Np). As shown by Equation 2, the Np values of the time-domain response may be described as a linear combination of Br basis functions, and the Br weights of the linear combination may be the vector c (e.g., c0[m] to c Br-1 [m]). In some examples, different time-domain responses

[0140] [Number]

[0141] can use the same basis functions (e.g., U matrix), but different c vectors (e.g., weights).

[0142]

[0137] In some examples, multiple techniques may be used to determine the spatial domain basis functions. Different techniques may be applied, for example, for the antenna port array at the transmitting device or base station and the antenna port array at the receiving device or UE, to select the spatial domain basis functions. In one example, the UE may select the spatial domain basis functions, for example, by evaluating an autocorrelation matrix of the UE antenna port array or the base station antenna port array. In some examples, the UE may evaluate the autocorrelation matrix by directly measuring the correlation between each pair of antenna ports (e.g., each pair of antenna ports at the UE, or each pair of antenna ports at the base station and the base station). In some other examples, the UE may measure the lowest correlation pair of antenna ports (e.g., from a set of correlation pairs of antenna ports) and evaluate the correlation between other correlation pairs of antenna ports (e.g., of the set of correlation pairs of antenna ports) using linear interpolation. For example, to select the spatial domain basis functions based on the lowest correlation antenna port, the base station may indicate some antenna ports (e.g., two) in the antenna array of the base station that have the lowest correlation (e.g., with respect to other antenna ports in the respective antenna arrays). In response, the UE may evaluate the correlation between the indicated antenna ports and determine the spatial domain basis functions based on the correlation values.

[0143] In yet some other examples, the UE may use the 2D topology of the antenna array (e.g., at the UE or at the base station) as a model of the autocorrelation matrix. In such examples, the UE may measure the correlation of one or more pairs of ports (e.g., at the base station) and extrapolate the correlation for other pairs of antenna ports (e.g., of a set of correlated pairs of antenna ports at the base station) assuming that the correlation is of the form:

[0144]

number

[0145] where f1 and f2 may correspond to parameters of a 2D topology model that may be adjusted to fit the model to the observations, and d may correspond to the distance between the (e.g., two) antenna ports that are correlated. In some examples, the correlation between antenna port pairs at the base station may be measured (e.g., by the UE) using some type of reference signal (e.g., CSI-RS) to determine the autocorrelation matrix of the base station. In some other examples, another type of reference signal (e.g., SRS) may be used (e.g., by the base station) to determine the autocorrelation matrix of the UE. In some other cases, any downlink reference signal may be used to determine the autocorrelation matrix of the base station, and any uplink reference signal may be used to determine the autocorrelation matrix of the UE.

[0146] In some other examples, the UE may determine the spatial domain basis functions by performing SVD on a spatial autocorrelation matrix. For example, the SVD may be expressed as: [U,S,V] = svd(R bs ) (3) where U, S, and V may each be an N×N matrix, and R bs may be the autocorrelation matrix at the base station.

[0147] In such an example, the UE may select the first B vectors (e.g., eigenvectors) corresponding to the largest B eigenvalues ​​(e.g., of a set of eigenvalues). For example, the UE may find an eigenvector corresponding to a linear combination of antenna ports that may experience a relatively large amount of variation (e.g., in the channel response) compared to the variation in the channel response for other linear combinations of antenna ports. In some examples, the selected eigenvectors (e.g., basis functions) may be expressed as follows:

[0148]

number

[0149]

[0141] In some examples, one or more signals may support the evaluation of the autocorrelation matrix. For example, the base station may indicate to the UE (e.g., or the UE may indicate to the base station) one or more antenna port pairs that have relatively low correlation. In some examples, the base station may indicate to the UE (e.g., or the UE may indicate to the base station) the 2D topology of the antenna array of the respective device. In other examples, the base station may indicate to the UE the UE autocorrelation matrix. In some cases, the indication may be direct or in a different manner (e.g., the indication may correspond to a difference from a previous state). In some examples, the base station may indicate which of the antenna port pairs at the UE corresponds to, for example, the lowest correlation antenna port pair of the set of antenna port pairs. In some other examples, the base station may indicate to the UE the 2D topology model (e.g., f1 and f2).

[0150] In some examples, one or more signals may support the selection of spatial domain basis functions. For example, the base station may select the spatial domain basis function (e.g., B T Or B R The base station can indicate to the UE the number of spatial domain basis functions (e.g., B T Or B R) to be used. In some cases, the UE may report the number of spatial domain basis functions to be used to the base station. In other cases, the base station may indicate the spatial domain basis function values ​​of the receive antennas or the index of a predefined set of basis functions to the UE. In further cases, the indication may be a direct manner or a different manner (e.g., the indication may correspond to a difference from a previous state). The UE may indicate the basis function values ​​of the transmit antennas or the index of a predefined set of basis functions to the base station. In some examples, the indication may be a direct manner or a different manner (e.g., the indication may correspond to a difference from a previous state). In some examples, each arbitrary indication may be transmitted periodically (e.g., with a dedicated periodicity for each indication type) or aperiodically. For example, the indication may be communicated using a DCI, a medium access control-control element (MAC-CE), or an RRC message.

[0151]

[0143] In some examples, the spatial model may be written separately from the perspective of a transmitting device (eg, a base station) as follows:

[0152]

number

[0153] From the perspective of the receiving device (e.g., UE):

[0154]

number

[0155] where

[0156]

number

[0157] may represent the time-domain response of the channel measured at the (i-th) antenna port of the base station and the UE, respectively (e.g., where i ranges from 0 to Np-1), and c i [m] represents the time-space response of the estimated channel.

[0158]

[0144] In such an example, the time domain response of the channel may be written as follows:

[0159]

number

[0160] A 2D model (e.g., a spatio-temporal model) may be expressed as a Kronecker product of the time-domain response of the channel and the spatial model. For example, the 2D model may be written as:

[0161]

number

[0162] where c may be a vector representing the channel coefficients, A may represent a 2D model, and σ 2 may represent the SNR, I may represent the identity matrix, and h FD may represent the measured frequency domain response of the channel. That is, Equation 8 expresses the measured frequency domain response of the channel (h FD ) and the channel coefficients (c) that represent the compressed channel response. In some examples, the values ​​of the channel coefficients (e.g., vector c) may be calculated using the linear minimum mean square error (LMMSE) of the following equation: c = (A H ·A+σ 2 I) -1 A H h FD (9)

[0163] Additionally or alternatively, the channel coefficients (c) may be calculated for each CSF report using an LMMSE solution (eg, an adaptive version of the SNR).

[0164] In some examples, the UE may dynamically evaluate different combinations of channel compression parameters to determine a channel compression configuration that may reduce an expected error (e.g., MSE). For example, dynamic configuration of channel compression may be used such that for a given report size, the UE may dynamically (e.g., for each report) evaluate one or more configuration options (e.g., having a report size equal to or smaller than a predetermined size), select an option with a desired performance (e.g., reduced MSE), and transmit a report (e.g., an indication of a set of channel coefficients) accordingly. In some examples, dynamically evaluating different combinations of channel compression parameters may improve performance, for example, by improving the trade-off between channel compression parameters (e.g., for each realized channel response). In some examples, parameters that may be considered for dynamic configuration may include some spatial domain basis functions, some spatial domain basis function indices (e.g., corresponding to one or more predefined spatial domain basis functions), some time domain basis functions, or some quantization bits.

[0165]

[0146] In some examples, one or more options may be considered to achieve reduced signaling overhead. For example, the time domain basis functions and the spatial domain basis functions may be ordered with respect to their expected contribution to performance. In some examples, as the number of basis functions increases, the accuracy of the compressed channel estimation also increases. However, the contribution of each basis function to the achieved accuracy may not be the same. Thus, the basis functions may be ordered according to expected contribution (e.g., according to the corresponding eigenvalue order) such that when the UE decides (e.g., dynamically) to reduce the number of basis functions to a certain number (K), the UE may select the top K basis functions from the ordered list. Thus, rather than reporting the selected basis function (e.g., K indices each corresponding to a selected basis function), the UE may report the value K, thereby reducing overhead.

[0166]

[0147] The number of time domain basis functions and the number of spatial domain basis functions may be dynamically signaled (e.g., to the UE) and selected according to an ordering. The UE may switch between one or more different configuration sets (e.g., sets of dynamic configuration parameters), e.g., using a dedicated set selection parameter. In some examples, each configuration option may be determined based on the number of time domain basis functions or the number of spatial domain basis functions. In some examples, the number of time domain basis functions or the number of spatial domain basis functions may be indicated together (e.g., together) with the number of quantization bits (e.g., the number of bits used for quantization). In some examples, one or more basis functions (e.g., spatial domain basis functions or time domain basis functions) may be replaced by the UE using one or more dedicated parameters.

[0167]

[0148] In some examples, the base station may indicate to the UE an ordering of spatial domain basis functions from which the UE may dynamically select one or more spatial domain basis functions to be used in the spatial model. In some examples, the UE may report to the base station the selected spatial domain basis functions or the ordering of the selected spatial domain basis functions (e.g., to reconstruct the spatial model). The base station may indicate an ordering of time domain basis functions from which the UE may dynamically select one or more time domain basis functions to be used in the time domain response of the channel. In some examples, the UE may report to the base station the selected time domain basis functions or the ordering of the selection of the time domain basis functions (e.g., to reconstruct the time domain response of the channel). The base station may indicate a list of configuration sets (e.g., one or more configurations including a set of spatial domain basis functions and a set of time domain basis functions) from which the UE may dynamically select a configuration to be used to determine the time domain response and spatial model of the channel. In some examples, the UE may report the selected configuration to the base station. Each configured set may include a number of spatial domain basis functions, a number of time domain basis functions, or a number of bits to use for quantization. In some examples, the UE may report the selected configuration to the base station. In some examples, the base station may indicate to the UE a number of time domain basis functions, a number of spatial domain basis functions, or a number of bits to use for quantization. In some other examples, the UE may report to the base station the number of time domain basis functions, the number of spatial domain basis functions, or the number of bits to use for quantization. In some examples, one or more of the indications may be indicated via a DCI, a MAC-CE, or an RRC message.

[0168] 6A and 6B each illustrate an example of a differential encoding scheme 600 supporting channel compression of channel feedback reports according to aspects of the present disclosure. In some examples, the differential encoding scheme 600 (e.g., the differential encoding scheme 600-a and the differential encoding scheme 600-b) may include aspects of the wireless communication systems 100 and 200 described with respect to Figures 1 and 2, respectively. For example, the differential encoding scheme 600 may be implemented by a UE 115, which may be an example of a corresponding device described with reference to Figures 1 and 2.

[0169] As shown in the example of FIG. 6A, the UE may use differential coding to increase the accuracy with which the set of channel coefficients represents the estimated channel. In some cases of differential coding, the UE may transmit (e.g., indicate) channel coefficients at a reduced periodicity, e.g., in an intra-coded slot (e.g., I slot 610), and transmit (e.g., indicate) changes in the set of channel coefficients at an inter-coded slot (e.g., P slot 615). In other words, differential coding may include transmitting channel coefficients at a low periodicity in an "intra-coded slot" ("I slot") and transmitting changes in the coefficients at other "inter-coded slots" ("P slots"). In an example of differential coding option 605-a, the changes in the channel coefficients indicated in a given P slot 615 (e.g., P slot 615-b) may be measured with respect to the value of the channel coefficient measured in an anchor slot (e.g., I slot 610-a). For example, the channel coefficients may be differential with respect to the anchor slot (I slot). In an example of differential encoding option 605-b, the change in the channel coefficients indicated in a given P slot 615 (e.g., P slot 615-e) may be measured relative to a previous slot (e.g., P slot 615-d). For example, the channel coefficients may be differential relative to the previous slot. In some cases, the change may be measured from a reconstructed channel at the receiver (e.g., from the perspective of the base station).

[0170] As shown in the example of FIG. 6B, the UE may perform 2D channel estimation 620 to obtain a set of channel coefficients. At 625, the UE may compress the set of channel coefficients using quantization 630. In some examples, the 2D channel estimation and quantization 630 may be examples of the corresponding processes described with reference to FIG. 3. In some examples, at 635, channel coefficients corresponding to a reconstructed channel (e.g., reconstructed channel coefficients) may be subtracted from the quantized set of channel coefficients to calculate a set of differential channel coefficients (e.g., via operator 645). In some examples, operator 645 may output the set of differential channel coefficients to differential information 685 transmitted on a P slot at 650. In some cases, the P slot may be an example of a P slot described with reference to FIG. 6A. Additionally or alternatively, at 655, the set of differential channel coefficients may be input to a differential decoder 660. For example, the set of differential channel coefficients may be input to a multiplexer 665. At 640, the set of channel coefficients generated from the 2D channel estimate 620 (e.g., the set of channel coefficients transmitted in an I slot) may be input to a differential decoder 660. In some cases, the I slot may be an example of an I slot described with reference to FIG. 6A. For example, the set of channel coefficients may be input to a multiplexer 665. In some cases, the set of channel coefficients may be multiplexed with the set of differential channel coefficients via the multiplexer 665. At 670, the output of the multiplexer 665 may be input (e.g., stored) to an accumulator 675. In some examples, the accumulator 675 may reset on the I slot (e.g., the anchor slot). At 680, the output of the accumulator 675 (e.g., the reconstructed channel coefficients) may be subtracted from the quantized set of channel coefficients via an operator 645, and the output may correspond to the set of differential channel coefficients measured for the previous P slot.

[0171] In some examples, an entropy encoder may be applied to the output of the differential encoder (e.g., differential decoder 660) to, for example, compress a transmitted message (e.g., an indication of a set of differential channel coefficients). In some examples, the entropy encoder may take advantage of the relatively high imbalance in the probabilities of the output values ​​of the differential decoder 660. In some examples, the dictionary of the entropy encoder (e.g., or entropy decoder) may have a different configuration. For example, the dictionary of the entropy encoder may be a predefined dictionary (e.g., in terms of the number of quantization bits), or the dictionary of the entropy encoder may be updated (e.g., over time) by collecting and analyzing statistics of the output values ​​of the differential decoder 660.

[0172] 7 illustrates an example of a performance response diagram 700 supporting channel compression of channel feedback reports in accordance with aspects of the present disclosure. In some examples, the performance response diagram 700 may implement or be implemented by aspects of the wireless communications systems 100 and 200. For example, the performance response diagram 700 may be associated with communications between a base station and a UE, which may be examples of corresponding devices described with reference to FIGS. 1 and 2.

[0173]

[0154] As shown in the example of Figure 7, the accuracy with which a channel estimation report (e.g., a set of channel coefficients indicated to a base station) represents an estimated channel may depend on the number of bits (e.g., the average number of bits per coefficient) used to represent the estimated channel. For example, performance response diagram 700 shows the NMSE of a compressed channel (e.g., obtained from an MMSE solution of a 2D model) plotted as a function of bits, where performance response 715 (e.g., performance response 715-a and performance response 715-b) represent a set of channel coefficients generated using a set of basis functions that may be updated every 60 slots, and performance response 710 (e.g., performance response 710-a and performance response 710-b) represent a set of channel coefficients generated using a set of basis functions that may be updated every 16 slots. In some examples, performance response 715-b and performance response 710-b may represent performance using differential decoding (e.g., encoding). For example, the respective sets of channel coefficients used to achieve performance response 715-b and performance response 710-b may be sets of differential channel coefficients generated using differential encoding as described throughout this disclosure, including with respect to Figures 6A and 6B.

[0174] In the example of FIG. 7, the performance of different tradeoffs between signaling overhead in bits and accuracy of channel estimation report (e.g., NMSE of compressed channel response) may be based on 20 MHz channel bandwidth, 32 antenna ports at the transmitting device (e.g., base station), and one antenna port at the receiving device (e.g., UE). In some examples, different tradeoffs (e.g., performance responses) may be achieved using different numbers of time domain basis functions, different numbers of spatial domain basis functions, or different numbers of quantization bits (e.g., bits used for quantization of the set of channel coefficients). As shown in the example of FIG. 7, applying a differential encoder may reduce signaling overhead. For example, arrow 725 indicates a reduction in signaling overhead (e.g., number of bits) between performance response 715-a and performance response 715-b, and arrow 720 indicates a reduction in signaling overhead (e.g., number of bits) between performance response 710-a and performance response 710-b.

[0175]

[0156] In some examples, the base station may indicate to the UE the number of bits for quantization used, or in some other examples, the UE may report to the base station the number of bits used for quantization by the UE. In some examples, the base station may send an instruction to the UE for the UE to enable or disable differential encoding. In some other examples, the UE may indicate to the base station whether differential encoding may be enabled or disabled. The base station may indicate to the UE a method for differential encoding. For example, the UE may indicate whether a set of differential channel coefficients may be measured for P slots or I slots. In some examples, the method for differential encoding may be based on the mobility of the UE and the time gap (e.g., interval) between CSF reports (e.g., successive CSF reports). The base station may indicate an I slot period to the UE, or the UE may indicate an I slot period to the base station. The base station may indicate a dictionary for the entropy encoder to the UE, or the UE may report a dictionary for the entropy encoder to the base station. In some examples, a dictionary for an entropy encoder may be indicated to multiple UEs (e.g., jointly) to reduce complexity associated with operations at the base station. In some examples, the base station may indicate a desired accuracy of the report (e.g., a desired NMSE or MSE of the compressed channel response), and the UE may determine a number of bits or I-slot periods for quantization to use based on the desired accuracy indicated to the UE.

[0176]

[0157] In some examples, one or more of the indications may be transmitted periodically or aperiodically. For example, the indications may be transmitted periodically based on a predefined value determined by the base station and the UE, a predefined value per UE speed, or a value updated by the base station (e.g., via an RRC message). In such an example, each indication may have a dedicated period. In another example, the basis functions may be updated aperiodically. For example, the UE or the base station may request aperiodically updating the basis vectors based on the UE's mobility or reduced MSE (e.g., a drop in the measured MSE). In such an example, each indication may be communicated using a DCI, a MAC-CE, or an RRC message.

[0177] FIG. 8 illustrates an example of a process flow 800 supporting channel compression of channel feedback reports according to aspects of the disclosure. In some examples, the process flow 800 may implement or be implemented by one or more aspects of the wireless communication systems 100 and 200. For example, the process flow 800 may be implemented by the base station 105-b and the UE 115-b, which may be examples of corresponding devices described with reference to FIG. 1 and FIG. 2. In the following description of the process flow 800, operations between the UE 115-b and the base station 105-b may be transmitted in a different order than the example order shown, or operations performed by the UE 115-b and the base station 105-b may be performed in a different order or at different times. Some operations may be omitted.

[0178]

[0159] As shown in the example of FIG. 8, the UE 115-b may receive one or more reference signals from the base station 105-b at 805. In some examples, the UE 115-b may receive one or more reference signals over a channel for communication between the UE 115-b and the base station 105-b. In some cases, the one or more reference signals may be reference signals (e.g., CSI-RSs) described with reference to FIG. 5. In 810, the UE 115-b may measure a response of the channel. In some examples, the UE 115-b may measure a response based on the one or more reference signals received over the channel. In 815, the UE 115-b may transmit a message indicating a set of channel coefficients. In some cases, the set of channel coefficients may correspond to a 2D model representing the response. In some examples, the 2D model may include a spatial model and a time domain response of the channel. In some cases, the spatial model and the time domain response of the channel may be examples of the spatial model and the time domain response of the channel described with reference to FIGS. 3-5.

[0179] 9 illustrates a block diagram 900 of a device 905 supporting channel compression of channel feedback reports according to aspects of the disclosure. The device 905 may be an example of an aspect of a UE 115 described herein. The device 905 may include a receiver 910, a transmitter 915, and a communications manager 920. The device 905 may also include a processor. Each of these components may be in communication with one another (e.g., via one or more buses).

[0180] The receiver 910 may provide a means for receiving information such as packets associated with various information channels (e.g., control channels, data channels, information channels for channel compression for channel feedback reports), user data, control information, or any combination thereof. The information may be passed to other components of the device 905. The receiver 910 may utilize a single antenna or a set of multiple antennas.

[0181] The transmitter 915 can provide a means for transmitting signals generated by other components of the device 905. For example, the transmitter 915 can transmit information such as packets associated with various information channels (e.g., control channels, data channels, information channels for channel compression for channel feedback reports), user data, control information, or any combination thereof. In some examples, the transmitter 915 can be collocated with the receiver 910 in a transceiver module. The transmitter 915 may utilize a single antenna or a set of multiple antennas.

[0182]

[0163] The communications manager 920, the receiver 910, the transmitter 915, or various combinations or components thereof may be examples of means for performing various aspects of channel compression of channel feedback reports described herein. For example, the communications manager 920, the receiver 910, the transmitter 915, or various combinations or components thereof may support a method for performing one or more of the functions described herein.

[0183] In some examples, the communications manager 920, the receiver 910, the transmitter 915, or various combinations or components thereof may be implemented in hardware (e.g., in a communications management circuit). The hardware may include a processor, a digital signal processor (DSP), an application-specific integrated circuit (ASIC), a field-programmable gate array (FPGA) or other programmable logic device, discrete gate or transistor logic, discrete hardware components, or any combination thereof configured as or otherwise supporting a means for performing the functions described in this disclosure. In some examples, the processor and a memory coupled to the processor may be configured to perform one or more of the functions described herein (e.g., by the processor executing instructions stored in the memory).

[0184] Additionally or alternatively, in some examples, the communications manager 920, the receiver 910, the transmitter 915, or various combinations or components thereof may be implemented in code executed by a processor (e.g., as communications management software or firmware). When implemented in code executed by a processor, the functions of the communications manager 920, the receiver 910, the transmitter 915, or various combinations or components thereof may be performed by a general purpose processor (e.g., configured as or otherwise supporting a means for performing the functions described in this disclosure), a DSP, a central processing unit (CPU), an ASIC, an FPGA, or any combination of these or other programmable logic devices.

[0185] In some examples, the communications manager 920 can be configured to perform various operations (e.g., receiving, monitoring, transmitting) using or otherwise cooperating with the receiver 910, the transmitter 915, or both. For example, the communications manager 920 may receive information from the receiver 910 and transmit information to the transmitter 915, or may be integrated in combination with the receiver 910, the transmitter 915, or both to receive information, transmit information, or perform various other operations described herein.

[0186]

[0167] The communications manager 920 may support wireless communications in the UE according to examples disclosed herein. For example, the communications manager 920 may be configured or otherwise support a means for receiving at least one reference signal from a base station over a communications channel for wireless communications between the UE and the base station. The communications manager 920 may be configured or otherwise support a means for determining a response of a communications channel based on at least one reference signal received over the communications channel. The communications manager 920 may be configured or otherwise support a means for transmitting a message to the base station indicating a set of channel coefficients corresponding to a 2D model representing the response, the 2D model including a spatial model and a time domain response of the communications channel.

[0187]

[0168] By including or configuring a communications manager 920 in accordance with the examples described herein, the device 905 (e.g., a processor controlling or otherwise coupled to the receiver 910, the transmitter 915, the communications manager 920, or a combination thereof) may support techniques for reducing processing and more efficient utilization of communications resources.

[0188] 10 illustrates a block diagram 1000 of a device 1005 supporting channel compression of channel feedback reports according to aspects of the disclosure. The device 1005 may be an example of an aspect of a device 905 or a UE 115 described herein. The device 1005 may include a receiver 1010, a transmitter 1015, and a communications manager 1020. The device 1005 may also include a processor. Each of these components may be in communication with each other (e.g., via one or more buses).

[0189] The receiver 1010 may provide a means for receiving information such as packets associated with various information channels (e.g., control channels, data channels, information channels for channel compression for channel feedback reports), user data, control information, or any combination thereof. The information may be passed to other components of the device 1005. The receiver 1010 may utilize a single antenna or a set of multiple antennas.

[0190] The transmitter 1015 may provide a means for transmitting signals generated by other components of the device 1005. For example, the transmitter 1015 may transmit information such as packets associated with various information channels (e.g., control channels, data channels, information channels for channel compression for channel feedback reports), user data, control information, or any combination thereof. In some examples, the transmitter 1015 may be collocated with the receiver 1010 in a transceiver module. The transmitter 1015 may utilize a single antenna or a set of multiple antennas.

[0191]

[0172] The device 1005 or various components thereof may be an example of a means for performing various aspects of channel compression of channel feedback reports described herein. For example, the communication manager 1020 may include a reference signal receiving component 1025, a channel response component 1030, a message sending component 1035, or any combination thereof. The communication manager 1020 may be an example of an aspect of the communication manager 920 described herein. In some examples, the communication manager 1020 or various components thereof may be configured to perform various operations (e.g., receiving, monitoring, transmitting) using or otherwise cooperating with the receiver 1010, the transmitter 1015, or both. For example, the communication manager 1020 may receive information from the receiver 1010 and transmit information to the transmitter 1015, or may be integrated in combination with the receiver 1010, the transmitter 1015, or both to receive information, transmit information, or perform various other operations described herein.

[0192]

[0173] The communications manager 1020 may support wireless communications in the UE according to examples disclosed herein. The reference signal receiving component 1025 may be configured or otherwise support a means for receiving at least one reference signal from a base station over a communications channel for wireless communications between the UE and the base station. The channel response component 1030 may be configured or otherwise support a means for determining a response of a communications channel based on at least one reference signal received over the communications channel. The message sending component 1035 may be configured or otherwise support a means for sending a message to the base station indicating a set of channel coefficients corresponding to a 2D model representing the response, the 2D model including a spatial model and a time domain response of the communications channel.

[0193] FIG. 11 illustrates a block diagram 1100 of a communications manager 1120 supporting channel compression of channel feedback reports according to aspects of the disclosure. The communications manager 1120 may be an example of aspects of the communications manager 920, the communications manager 1020, or both described herein. The communications manager 1120, or various components thereof, may be an example of a means for performing various aspects of the channel compression of channel feedback reports described herein. For example, the communications manager 1120 may include a reference signal receiving component 1125, a channel response component 1130, a message sending component 1135, a time domain response component 1140, a channel coefficient component 1145, a 2D model component 1150, a differential channel coefficient component 1155, an ordering component 1160, a spatial model component 1165, an antenna port pair component 1170, a differential encoding component 1175, a timing component 1180, or any combination thereof. Each of these components may communicate directly or indirectly with each other (e.g., via one or more buses).

[0194]

[0175] The communications manager 1120 may support wireless communications in the UE according to examples disclosed herein. The reference signal receiving component 1125 may be configured as or otherwise support a means for receiving at least one reference signal from a base station over a communication channel for wireless communications between the UE and the base station. The channel response component 1130 may be configured as or otherwise support a means for determining a response of a communication channel based on at least one reference signal received over the communication channel. The message sending component 1135 may be configured as or otherwise support a means for sending a message to the base station indicating a set of channel coefficients corresponding to a 2D model representing the response, the 2D model including a spatial model and a time domain response of the communication channel.

[0195] In some examples, the channel response component 1130 may be configured or otherwise support a means for determining a frequency domain response of the communication channel as part of determining the response, and in some examples, the time domain response component 1140 may be configured or otherwise support a means for generating a time domain response based on the frequency domain response of the communication channel.

[0196] In some examples, the spatial model component 1165 may be configured as or otherwise support a means for generating a spatial model based on a time-domain or frequency-domain response of the communication channel. In some examples, the two-dimensional model is a Kronecker product of a matrix representation of the spatial model and a matrix representation of the time-domain response of the communication channel.

[0197] In some examples, the channel coefficient component 1145 may be configured or otherwise support a means for generating a set of channel coefficients based on an MMSE solution between the determined response and the 2D model. In some examples, the set of channel coefficients includes a set of quantized coefficients. In some examples, the 2D model component 1150 may be configured or otherwise support a means for generating a 2D model based on one or more antennas at the UE, one or more antennas at the base station, or both.

[0198] In some examples, to support transmitting the message, the message transmitting component 1135 may be configured or otherwise support a means for transmitting a set of bits indicative of a set of channel coefficients to the base station over a control channel or a shared channel. In some examples, the message transmitting component 1135 may be configured or otherwise support a means for transmitting an indication of a number of quantization bits for the message to the base station based on a mean squared error or signal to noise ratio of the communication channel.

[0199] In some examples, the channel coefficient component 1145 may be configured or otherwise support a means for transmitting a set of channel coefficients in a first slot. In some examples, the differential channel coefficient component 1155 may be configured or otherwise support a means for transmitting a set of differential channel coefficients in a second slot after the first slot, the set of differential channel coefficients, each differential channel coefficient of the set of differential channel coefficients including a channel coefficient difference with respect to a respective channel coefficient of the set of channel coefficients.

[0200]

[0181] In some examples, the channel coefficient component 1145 may be configured or otherwise support a means for transmitting a second set of channel coefficients different from the set of channel coefficients in a third slot after the first slot, and the set of channel coefficients and the second set of channel coefficients are transmitted in accordance with the first period.

[0201]

[0182] In some examples, the differential channel coefficient component 1155 may be configured or otherwise support a means for transmitting, in a fourth slot after the second slot, a second set of differential channel coefficients, where each differential channel coefficient of the second set of differential channel coefficients includes a channel coefficient difference relative to a respective channel coefficient of the set of channel coefficients or a respective differential channel coefficient of the set of differential channel coefficients, and the set of differential channel coefficients and the second set of differential channel coefficients are transmitted according to a second periodicity different from the first periodicity.

[0202] In some examples, the differential channel coefficient component 1155 may be configured or otherwise support a means for receiving an instruction from a base station instructing the UE to enable transmission of a set of differential channel coefficients, and transmitting the set of differential channel coefficients is based on receiving the instruction. In some examples, the differential encoding component 1175 may be configured or otherwise support a means for receiving an instruction from a base station instructing the UE to use a differential encoding procedure based on the mobility of the UE or a time interval between a message indicating a set of channel coefficients and a previous message indicating a previous set of channel coefficients.

[0203] In some examples, the ordering component 1160 may be configured or otherwise support a means for receiving an indication of an ordering of the set of spatial domain basis functions from a base station. In some examples, the spatial model component 1165 may be configured or otherwise support a means for generating a spatial model based on an ordering of the set of spatial domain basis functions. In some examples, the indication includes a configuration of a spatial model that includes a list of spatial domain basis functions. In some examples, the list of spatial domain basis functions corresponds to an ordering of the set of spatial domain basis functions.

[0204] In some examples, the ordering component 1160 may be configured or otherwise support receiving an indication of an ordering of the set of time domain basis functions from a base station. In some examples, the time domain response component 1140 may be configured or otherwise support generating a time domain response based on an ordering of the set of time domain basis functions. In some examples, the ordering component 1160 may be configured or otherwise support transmitting an indication of an ordering of the set of spatial domain basis functions, an ordering of the set of time domain basis functions, or both.

[0205] In some examples, the channel response component 1130 may be configured or otherwise support a means for determining a time domain response of a communication channel at a set of multiple timings for each of a set of multiple antenna port pairs as part of determining the response. In some examples, the time domain response component 1140 may be configured or otherwise support a means for selecting a set of time domain basis functions based on determining the time domain response of the communication channel at a set of multiple timings. In some examples, the time domain response component 1140 may be configured or otherwise support a means for generating a time domain response based on a selected set of time domain basis functions.

[0206] In some examples, the time domain response component 1140 may be configured or otherwise support a means for determining an accumulated energy of a time domain response across a set of multiple antenna port pairs for each timing of the set of multiple timings. In some examples, the timing component 1180 may be configured or otherwise support a means for selecting a set of timings from the set of multiple timings based on determining an accumulated energy of a time domain response for each timing of the set of multiple timings, where selecting the set of time domain basis functions is based on the selected set of timings.

[0207] In some examples, the channel response component 1130 may be configured or otherwise support a means for evaluating a mean squared error of the determined response and a channel estimate using a selected set of timings, and selecting a set of time domain basis functions is based on evaluating the mean squared error. In some examples, the timing component 1180 may be configured or otherwise support a means for receiving an indication of a number of timings from a base station, and selecting a set of time domain basis functions is based on the indicated number of timings.

[0208]

[0189] In some examples, the timing component 1180 may be configured with or otherwise support a means for transmitting an indication of some of the timings of a plurality of timing sets to a base station.

[0209] In some examples, the antenna port pair component 1170 may be configured or otherwise support a means for receiving an indication of a set of antenna port pairs from a base station. In some examples, the channel response component 1130 may be configured or otherwise support a means for determining a correlation between each antenna port pair of the set of antenna port pairs, associated with a UE or a base station, as part of determining a response. In some examples, the antenna port pair component 1170 may be configured or otherwise support a means for selecting a set of spatial domain basis functions based on determining a correlation between each antenna port pair of the set of antenna port pairs. In some examples, the spatial model component 1165 may be configured or otherwise support a means for generating a spatial model based on a selected set of spatial domain basis functions.

[0210] In some examples, the antenna port pair component 1170 may be configured or otherwise support a means for selecting a set of spatial domain basis functions based on a lowest determined correlation for an antenna port pair of the set of antenna port pairs. In some examples, the antenna port pair component 1170 may be configured or otherwise support a means for evaluating a spatial autocorrelation matrix based on determining a correlation between each antenna port pair of the set of antenna port pairs, and selecting the set of spatial domain basis functions is based on the spatial autocorrelation matrix.

[0211] 12 illustrates a diagram of a system 1200 including a device 1205 supporting channel compression of channel feedback reports according to aspects of the disclosure. The device 1205 may be an example of or may include components of the device 905, device 1005, or UE 115 described herein. The device 1205 may wirelessly communicate with one or more base stations 105, UE 115, or any combination thereof. The device 1205 may include components for two-way voice and data communication, including components for transmitting and receiving communications, such as a communications manager 1220, an input / output (I / O) controller 1210, a transceiver 1215, an antenna 1225, a memory 1230, code 1235, and a processor 1240. These components may be in electronic communication or otherwise coupled (e.g., operatively, communicatively, functionally, electronically, electrically) via one or more buses (e.g., bus 1245).

[0212]

[0193] The I / O controller 1210 may manage input and output signals for the device 1205. The I / O controller 1210 may also manage peripheral devices that are not integrated with the device 1205. In some cases, the I / O controller 1210 may represent a physical connection or port to an external peripheral device. In some cases, the I / O controller 1210 may utilize an operating system such as iOS®, ANDROID®, MS-DOS®, MS-WINDOWS®, OS / 2®, UNIX®, LINUX®, or another known operating system. Additionally or alternatively, the I / O controller 1210 may represent or interact with a modem, keyboard, mouse, touch screen, or similar device. In some cases, the I / O controller 1210 may be implemented as part of a processor, such as the processor 1240. In some cases, a user may interact with the device 1205 through the I / O controller 1210 or through hardware components controlled by the I / O controller 1210 .

[0213] In some cases, the device 1205 may include a single antenna 1225. However, in some other cases, the device 1205 may have two or more antennas 1225, which may be capable of simultaneously transmitting or receiving multiple wireless transmissions. The transceiver 1215 may communicate bidirectionally via one or more antennas 1225, a wired link, or a wireless link, as described herein. For example, the transceiver 1215 may represent a wireless transceiver and may communicate bidirectionally with another wireless transceiver. The transceiver 1215 may also include a modem for modulating packets and providing the modulated packets to one or more antennas 1225 for transmission, and for demodulating packets received from the one or more antennas 1225. The transceiver 1215, or the transceiver 1215 and one or more antennas 1225, may be an example of the transmitter 915, the transmitter 1015, the receiver 910, the receiver 1010, or any combination or component thereof described herein.

[0214]

[0195] The memory 1230 may include random access memory (RAM) and read-only memory (ROM). The memory 1230 may store computer-readable computer-executable code 1235 including instructions that, when executed by the processor 1240, cause the device 1205 to perform various functions described herein. The code 1235 may be stored in a non-transitory computer-readable medium, such as a system memory or another type of memory. In some cases, the code 1235 may not be directly executable by the processor 1240, but may (e.g., when compiled and executed) cause a computer to perform functions described herein. In some cases, the memory 1230 may include a basic I / O system (BIOS) that may control basic hardware or software operations, such as interactions with peripheral components or devices, among others.

[0215]

[0196] The processor 1240 may include an intelligent hardware device (e.g., a general-purpose processor, a DSP, a CPU, a microcontroller, an ASIC, an FPGA, a programmable logic device, a discrete gate or transistor logic component, a discrete hardware component, or any combination thereof). In some cases, the processor 1240 may be configured to operate a memory array using a memory controller. In some other cases, the memory controller may be integrated with the processor 1240. The processor 1240 may be configured to execute computer-readable instructions stored in a memory (e.g., the memory 1230) to cause the device 1205 to perform various functions (e.g., functions or tasks supporting channel compression of channel feedback reports). For example, the device 1205, or a component of the device 1205, may include the processor 1240 and the memory 1230 coupled with the processor 1240, and the processor 1240 and the memory 1230 are configured to perform various functions described herein.

[0216]

[0197] The communications manager 1220 may support wireless communications in the UE according to examples disclosed herein. For example, the communications manager 1220 may be configured or otherwise support a means for receiving at least one reference signal from a base station over a communication channel for wireless communications between the UE and the base station. The communications manager 1220 may be configured or otherwise support a means for determining a response of a communication channel based on at least one reference signal received over the communication channel. The communications manager 1220 may be configured or otherwise support a means for transmitting a message to the base station indicating a set of channel coefficients corresponding to a 2D model representing the response, the 2D model including a spatial model and a time domain response of the communication channel.

[0217]

[0198] By including or configuring a communications manager 1220 in accordance with the examples described herein, the device 1205 may support techniques for improving communication reliability, reducing latency, improving user experience with reduced processing, more efficient use of communications resources, and improving utilization of processing power.

[0218] In some examples, the communications manager 1220 can be configured to perform various operations (e.g., receiving, monitoring, transmitting) using or otherwise cooperating with the transceiver 1215, the one or more antennas 1225, or any combination thereof. Although the communications manager 1220 is shown as a separate component, in some examples, one or more functions described with respect to the communications manager 1220 may be supported or performed by the processor 1240, the memory 1230, the code 1235, or any combination thereof. For example, the code 1235 may include instructions executable by the processor 1240 to cause the device 1205 to perform various aspects of channel compression of the channel feedback reports described herein, or the processor 1240 and the memory 1230 can be otherwise configured to perform or support such operations.

[0219] 13 illustrates a block diagram 1300 of a device 1305 supporting channel compression of channel feedback reports according to an aspect of the disclosure. The device 1305 may be an example of an aspect of a base station 105 described herein. The device 1305 may include a receiver 1310, a transmitter 1315, and a communications manager 1320. The device 1305 may also include a processor. Each of these components may be in communication with each other (e.g., via one or more buses).

[0220] The receiver 1310 may provide a means for receiving information such as packets associated with various information channels (e.g., control channels, data channels, information channels for channel compression for channel feedback reports), user data, control information, or any combination thereof. The information may be passed to other components of the device 1305. The receiver 1310 may utilize a single antenna or a set of multiple antennas.

[0221] The transmitter 1315 may provide a means for transmitting signals generated by other components of the device 1305. For example, the transmitter 1315 may transmit information such as packets associated with various information channels (e.g., control channels, data channels, information channels for channel compression for channel feedback reports), user data, control information, or any combination thereof. In some embodiments, the transmitter 1315 may be collocated with the receiver 1310 in a transceiver module. The transmitter 1315 may utilize a single antenna or a set of multiple antennas.

[0222]

[0203] The communications manager 1320, the receiver 1310, the transmitter 1315, or various combinations or components thereof may be examples of means for performing various aspects of channel compression of channel feedback reports described herein. For example, the communications manager 1320, the receiver 1310, the transmitter 1315, or various combinations or components thereof may support a method for performing one or more of the functions described herein.

[0223] In some examples, the communications manager 1320, the receiver 1310, the transmitter 1315, or various combinations or components thereof, may be implemented in hardware (e.g., in a communications management circuit). The hardware may include a processor, a DSP, an ASIC, an FPGA or other programmable logic device, discrete gate or transistor logic, discrete hardware components, or any combination thereof configured as or otherwise supporting a means for performing the functions described in this disclosure. In some examples, the processor and a memory coupled to the processor may be configured to perform one or more of the functions described herein (e.g., by the processor executing instructions stored in the memory).

[0224] Additionally or alternatively, in some examples, the communications manager 1320, the receiver 1310, the transmitter 1315, or various combinations or components thereof may be implemented in code executed by a processor (e.g., as communications management software or firmware). When implemented in code executed by a processor, the functions of the communications manager 1320, the receiver 1310, the transmitter 1315, or various combinations or components thereof may be performed by a general-purpose processor (e.g., configured as or otherwise supporting a means for performing the functions described in this disclosure), a DSP, a CPU, an ASIC, an FPGA, or any combination of these or other programmable logic devices.

[0225] In some examples, the communications manager 1320 can be configured to perform various operations (e.g., receiving, monitoring, transmitting) using or otherwise cooperating with the receiver 1310, the transmitter 1315, or both. For example, the communications manager 1320 may receive information from the receiver 1310 and transmit information to the transmitter 1315, or may be integrated in combination with the receiver 1310, the transmitter 1315, or both to receive information, transmit information, or perform various other operations described herein.

[0226]

[0207] The communications manager 1320 may support wireless communications in the base station according to examples disclosed herein. For example, the communications manager 1320 may be configured or otherwise support a means for transmitting at least one reference signal to the UE over a communications channel for wireless communications between the UE and the base station. The communications manager 1320 may be configured or otherwise support a means for receiving a message from the UE indicating a set of channel coefficients corresponding to a 2D model representing a response of the communications channel, the 2D model including a spatial model and a time domain response of the communications channel.

[0227]

[0208] By including or configuring a communications manager 1320 in accordance with the examples described herein, the device 1305 (e.g., a processor controlling or otherwise coupled to the receiver 1310, the transmitter 1315, the communications manager 1320, or a combination thereof) can support techniques for reducing processing and more efficient utilization of communications resources.

[0228] 14 illustrates a block diagram 1400 of a device 1405 supporting channel compression of channel feedback reports according to aspects of the disclosure. The device 1405 may be an example of an aspect of the device 1305 or base station 105 described herein. The device 1405 may include a receiver 1410, a transmitter 1415, and a communications manager 1420. The device 1405 may also include a processor. Each of these components may be in communication with each other (e.g., via one or more buses).

[0229] The receiver 1410 may provide a means for receiving information such as packets associated with various information channels (e.g., control channels, data channels, information channels for channel compression for channel feedback reports), user data, control information, or any combination thereof. The information may be passed to other components of the device 1405. The receiver 1410 may utilize a single antenna or a set of multiple antennas.

[0230] The transmitter 1415 can provide a means for transmitting signals generated by other components of the device 1405. For example, the transmitter 1415 can transmit information such as packets associated with various information channels (e.g., control channels, data channels, information channels for channel compression for channel feedback reports), user data, control information, or any combination thereof. In some examples, the transmitter 1415 can be collocated with the receiver 1410 in a transceiver module. The transmitter 1415 may utilize a single antenna or a set of multiple antennas.

[0231]

[0212] The device 1405 or various components thereof may be an example of a means for performing various aspects of channel compression of channel feedback reports described herein. For example, the communication manager 1420 may include a reference signal transmission component 1425, a message reception component 1430, or any combination thereof. The communication manager 1420 may be an example of an aspect of the communication manager 1320 described herein. In some examples, the communication manager 1420 or various components thereof may be configured to perform various operations (e.g., receiving, monitoring, transmitting) using or otherwise cooperating with the receiver 1410, the transmitter 1415, or both. For example, the communication manager 1420 may receive information from the receiver 1410 and transmit information to the transmitter 1415, or may be integrated in combination with the receiver 1410, the transmitter 1415, or both to receive information, transmit information, or perform various other operations described herein.

[0232]

[0213] The communications manager 1420 may support wireless communications in a base station according to examples disclosed herein. The reference signal transmitting component 1425 may be configured or otherwise support a means for transmitting at least one reference signal to the UE over a communications channel for wireless communications between the UE and the base station. The message receiving component 1430 may be configured or otherwise support a means for receiving a message from the UE indicating a set of channel coefficients corresponding to a 2D model representing a response of the communications channel, the 2D model including a spatial model and a time domain response of the communications channel.

[0233] FIG. 15 illustrates a block diagram 1500 of a communications manager 1520 supporting channel compression of channel feedback reports according to aspects of the disclosure. The communications manager 1520 may be an example of aspects of the communications manager 1320, the communications manager 1420, or both described herein. The communications manager 1520, or various components thereof, may be an example of a means for performing various aspects of the channel compression of channel feedback reports described herein. For example, the communications manager 1520 may include a reference signal transmitting component 1525, a message receiving component 1530, a coefficient receiving component 1535, a differential coefficient receiving component 1540, an ordering indicating component 1545, a timing indicating component 1550, an antenna port pair indicating component 1555, an instruction component 1560, or any combination thereof. Each of these components may communicate directly or indirectly with each other (e.g., via one or more buses).

[0234]

[0215] The communications manager 1520 may support wireless communications in the base station according to examples disclosed herein. The reference signal transmitting component 1525 may be configured or otherwise support a means for transmitting at least one reference signal to the UE over a communications channel for wireless communications between the UE and the base station. The message receiving component 1530 may be configured or otherwise support a means for receiving a message from the UE indicating a set of channel coefficients corresponding to a 2D model representing a response of the communications channel, the 2D model including a spatial model and a time domain response of the communications channel.

[0235]

[0216] In some examples, the 2D model is a Kronecker product of a matrix representation of the spatial model and a matrix representation of the time domain response of the communication channel. In some examples, the set of channel coefficients includes a set of quantized coefficients. In some examples, to support receiving the message, the message receiving component 1530 may be configured as or otherwise support receiving from the UE a set of bits indicating the set of channel coefficients via a control channel or a shared channel. In some examples, the message receiving component 1530 may be configured as or otherwise support receiving from the UE an indication of a number of quantization bits for the message based on a mean squared error or a signal to noise ratio of the communication channel.

[0236] In some examples, the coefficient receiving component 1535 may be configured or otherwise support a means for receiving a set of channel coefficients in a first slot. In some examples, the differential coefficient receiving component 1540 may be configured or otherwise support a means for receiving a set of differential channel coefficients in a second slot after the first slot, the set of differential channel coefficients, each differential channel coefficient of the set of differential channel coefficients including a channel coefficient difference with respect to a respective channel coefficient of the set of channel coefficients.

[0237]

[0218] In some examples, the coefficient receiving component 1535 may be configured or otherwise support means for receiving a second set of channel coefficients different from the set of channel coefficients in a third slot after the first slot, and the set of channel coefficients and the second set of channel coefficients are received according to the first period.

[0238]

[0219] In some examples, the differential coefficient receiving component 1540 may be configured or otherwise support a means for receiving, in a fourth slot after the second slot, a second set of differential channel coefficients, where each differential channel coefficient of the second set of differential channel coefficients includes a channel coefficient difference relative to a respective channel coefficient of the set of channel coefficients or a respective differential channel coefficient of the set of differential channel coefficients, and the set of differential channel coefficients and the second set of differential channel coefficients are transmitted according to a second period different from the first period.

[0239] In some examples, the instructions component 1560 may be configured or otherwise support a means for sending an instruction to the UE instructing the UE to enable transmission of a set of differential channel coefficients, and receiving the set of differential channel coefficients is based on sending the instruction. In some examples, the instructions component 1560 may be configured or otherwise support a means for sending an instruction to the UE instructing the UE to use a differential encoding procedure based on mobility of the UE or a time interval between a message indicating the set of channel coefficients and a previous message indicating the previous set of channel coefficients.

[0240] In some examples, the ordering instruction component 1545 may be configured or otherwise support a means for transmitting to the UE an instruction of an ordering of a set of spatial domain basis functions for a 2D model. In some examples, the instruction includes a configuration of a spatial model that includes a list of spatial domain basis functions. In some examples, the list of spatial domain basis functions corresponds to an ordering of the set of spatial domain basis functions.

[0241] In some examples, the ordering indication component 1545 may be configured or otherwise support a means for transmitting an indication of an ordering of a set of time-domain basis functions for a 2D model to a UE. In some examples, the ordering indication component 1545 may be configured or otherwise support a means for receiving an indication of an ordering of a set of spatial-domain basis functions, an ordering of a set of time-domain basis functions for a 2D model, or both.

[0242] In some examples, the timing indication component 1550 may be configured or otherwise support a means for transmitting an indication of some timings for the 2D model to the UE. In some examples, the timing indication component 1550 may be configured or otherwise support a means for receiving an indication of some timings of a set of timings for the 2D model from the UE. In some examples, the antenna port pair indication component 1555 may be configured or otherwise support a means for transmitting an indication of a set of antenna port pairs to the UE, where each antenna port pair is associated with a UE or a base station.

[0243] FIG. 16 illustrates a diagram of a system 1600 including a device 1605 supporting channel compression of channel feedback reports according to aspects of the disclosure. The device 1605 may be or include an example of a component of a device 1305, a device 1405, or a base station 105 described herein. The device 1605 may wirelessly communicate with one or more base stations 105, UEs 115, or any combination thereof. The device 1605 may include components for two-way voice and data communication, including components for transmitting and receiving communications, such as a communications manager 1620, a network communications manager 1610, a transceiver 1615, an antenna 1625, a memory 1630, code 1635, a processor 1640, and an inter-station communications manager 1645. These components may be in electronic communication or otherwise coupled (e.g., operatively, communicatively, functionally, electronically, electrically) via one or more buses (e.g., a bus 1650).

[0244] The network communications manager 1610 may manage communications with the core network 130 (e.g., via one or more wired backhaul links). For example, the network communications manager 1610 may manage the forwarding of data communications for client devices, such as one or more UEs 115.

[0245] In some cases, the device 1605 may include a single antenna 1625. However, in some other cases, the device 1605 may have two or more antennas 1625, which may be capable of simultaneously transmitting or receiving multiple wireless transmissions. The transceiver 1615 may communicate bidirectionally via one or more antennas 1625, wired links, or wireless links as described herein. For example, the transceiver 1615 may represent a wireless transceiver and may communicate bidirectionally with another wireless transceiver. The transceiver 1615 may also include a modem for modulating packets and providing the modulated packets to one or more antennas 1625 for transmission, and for demodulating packets received from the one or more antennas 1625. The transceiver 1615, or the transceiver 1615 and one or more antennas 1625, may be an example of the transmitter 1315, the transmitter 1415, the receiver 1310, the receiver 1410, or any combination or component thereof described herein.

[0246]

[0227] The memory 1630 may include RAM and ROM. The memory 1630 may store computer-readable computer-executable code 1635 including instructions that, when executed by the processor 1640, cause the device 1605 to perform various functions described herein. The code 1635 may be stored in a non-transitory computer-readable medium, such as a system memory or another type of memory. In some cases, the code 1635 may not be directly executable by the processor 1640, but may (e.g., when compiled and executed) cause a computer to perform functions described herein. In some cases, the memory 1630 may include a BIOS that may control basic hardware or software operations, such as interactions with peripheral components or devices, among others.

[0247]

[0228] The processor 1640 may include an intelligent hardware device (e.g., a general-purpose processor, a DSP, a CPU, a microcontroller, an ASIC, an FPGA, a programmable logic device, a discrete gate or transistor logic component, a discrete hardware component, or any combination thereof). In some cases, the processor 1640 may be configured to operate a memory array using a memory controller. In some other cases, the memory controller may be integrated with the processor 1640. The processor 1640 may be configured to execute computer-readable instructions stored in a memory (e.g., the memory 1630) to cause the device 1605 to perform various functions (e.g., functions or tasks supporting channel compression of channel feedback reports). For example, the device 1605, or a component of the device 1605, may include the processor 1640 and the memory 1630 coupled with the processor 1640, and the processor 1640 and the memory 1630 are configured to perform various functions described herein.

[0248] The inter-station communications manager 1645 may manage communications with other base stations 105 and may include a controller or scheduler for controlling communications with the UE 115 in cooperation with the other base stations 105. For example, the inter-station communications manager 1645 may coordinate scheduling for transmissions to the UE 115 for various interference mitigation techniques, such as beamforming or joint transmission. In some examples, the inter-station communications manager 1645 may provide an X2 interface in LTE / LTE-A wireless communications network technology to communicate between the base stations 105.

[0249]

[0230] The communications manager 1620 may support wireless communications in the base station according to examples disclosed herein. For example, the communications manager 1620 may be configured or otherwise support a means for transmitting at least one reference signal to the UE over a communications channel for wireless communications between the UE and the base station. The communications manager 1620 may be configured or otherwise support a means for receiving a message from the UE indicating a set of channel coefficients corresponding to a 2D model representing a response of the communications channel, the 2D model including a spatial model and a time domain response of the communications channel.

[0250]

[0231] By including or configuring a communications manager 1620 in accordance with the examples described herein, the device 1605 may support techniques for improving communication reliability, reducing latency, improving user experience with reduced processing, reducing power consumption, more efficient use of communications resources, and improving utilization of processing power.

[0251] In some examples, the communications manager 1620 can be configured to perform various operations (e.g., receiving, monitoring, transmitting) using or otherwise cooperating with the transceiver 1615, the one or more antennas 1625, or any combination thereof. Although the communications manager 1620 is shown as a separate component, in some examples, one or more functions described with respect to the communications manager 1620 may be supported or performed by the processor 1640, the memory 1630, the code 1635, or any combination thereof. For example, the code 1635 may include instructions executable by the processor 1640 to cause the device 1605 to perform various aspects of channel compression of the channel feedback reports described herein, or the processor 1640 and the memory 1630 can be otherwise configured to perform or support such operations.

[0252]

[0233] Figure 17 illustrates a flow chart illustrating a method 1700 for supporting channel compression of channel feedback reports according to aspects of the present disclosure. The operations of the method 1700 may be implemented by a UE or components thereof as described herein. For example, the operations of the method 1700 may be performed by the UE 115 as described with reference to Figures 1-12. In some examples, the UE may execute a set of instructions to control functional elements of the UE to perform the described functions. Additionally or alternatively, the UE may perform aspects of the described functions using dedicated hardware.

[0253] At 1705, the method may include receiving at least one reference signal from the base station via a communication channel for wireless communication between the UE and the base station. The operations of 1705 may be performed according to examples as disclosed herein. In some examples, aspects of the operations of 1705 may be performed by a reference signal receiving component 1125 as described with reference to FIG.

[0254] At 1710, the method may include determining a response of the communication channel based on at least one reference signal received over the communication channel. The operations of 1710 may be performed according to examples as disclosed herein. In some examples, aspects of the operations of 1710 may be performed by a channel response component 1130 as described with reference to FIG.

[0255] At 1715, the method may include transmitting a message to the base station indicating a set of channel coefficients corresponding to a 2D model representing the response, the 2D model including a spatial model and a time domain response of the communication channel. The operations of 1715 may be performed according to examples as disclosed herein. In some examples, aspects of the operations of 1715 may be performed by a message transmitting component 1135 as described with reference to FIG.

[0256]

[0237] Figure 18 illustrates a flow chart illustrating a method 1800 for supporting channel compression of channel feedback reports according to aspects of the present disclosure. The operations of the method 1800 may be implemented by a UE or components thereof as described herein. For example, the operations of the method 1800 may be performed by the UE 115 as described with reference to Figures 1-12. In some examples, the UE may execute a set of instructions to control functional elements of the UE to perform the described functions. Additionally or alternatively, the UE may perform aspects of the described functions using dedicated hardware.

[0257] At 1805, the method may include receiving at least one reference signal from the base station via a communication channel for wireless communication between the UE and the base station. The operations of 1805 may be performed according to examples as disclosed herein. In some examples, aspects of the operations of 1805 may be performed by a reference signal receiving component 1125 as described with reference to FIG.

[0258] At 1810, the method may include determining a frequency domain response of the communication channel as part of determining the response. The operations of 1810 may be performed according to examples as disclosed herein. In some examples, aspects of the operations of 1810 may be performed by channel response component 1130 as described with reference to FIG.

[0259] At 1815, the method may include generating a time domain response based on the frequency domain response of the communication channel. The operations of 1815 may be performed according to examples as disclosed herein. In some examples, aspects of the operations of 1815 may be performed by a time domain response component 1140, as described with reference to FIG.

[0260] At 1820, the method may include transmitting a message to the base station indicating a set of channel coefficients corresponding to a two-dimensional model representing the response, the two-dimensional model including a spatial model and a time domain response of the communication channel. The operations of 1820 may be performed according to examples as disclosed herein. In some examples, aspects of the operations of 1820 may be performed by a message transmitting component 1135 as described with reference to FIG.

[0261] FIG. 19 illustrates a flow chart illustrating a method 1900 for supporting channel compression of channel feedback reports according to aspects of the present disclosure. The operations of the method 1900 may be implemented by a base station or components thereof as described herein. For example, the operations of the method 1900 may be performed by a base station 105 as described with reference to FIGS. 1-8 and 13-16. In some examples, the base station may execute a set of instructions to control functional elements of the base station to perform the described functions. Additionally or alternatively, the base station may perform aspects of the described functions using dedicated hardware.

[0262] At 1905, the method may include transmitting at least one reference signal to the UE over a communication channel for wireless communication between the UE and the base station. The operations of 1905 may be performed according to examples as disclosed herein. In some examples, aspects of the operations of 1905 may be performed by a reference signal transmitting component 1525 described with reference to FIG. 15.

[0263] At 1910, the method may include receiving a message from the UE indicating a set of channel coefficients corresponding to a 2D model representing a response of a communication channel, the 2D model including a spatial model and a time domain response of the communication channel. The operations of 1910 may be performed according to examples as disclosed herein. In some examples, aspects of the operations of 1910 may be performed by a message receiving component 1530 as described with reference to FIG.

[0264]

[0245] Figure 20 illustrates a flow chart illustrating a method 2000 for supporting channel compression of channel feedback reports according to aspects of the present disclosure. The operations of the method 2000 may be implemented by a base station or components thereof as described herein. For example, the operations of the method 2000 may be performed by a base station 105 as described with reference to Figures 1-8 and 13-16. In some examples, the base station may execute a set of instructions to control functional elements of the base station to perform the described functions. Additionally or alternatively, the base station may perform aspects of the described functions using dedicated hardware.

[0265]

[0246] At 2005, the method may include transmitting at least one reference signal to the UE over a communication channel for wireless communication between the UE and the base station. The operations of 2005 may be performed according to examples as disclosed herein. In some examples, aspects of the operations of 2005 may be performed by a reference signal transmitting component 1525 as described with reference to FIG.

[0266]

[0247] At 2010, the method may include receiving a message from a UE indicating a set of channel coefficients corresponding to a two-dimensional model representing a response of a communication channel, the two-dimensional model being a Kronecker product of a matrix representation of the spatial model and a matrix representation of a time-domain response of the communication channel. The operations of 2010 may be performed according to examples as disclosed herein. In some examples, aspects of the operations of 2010 may be performed by a message receiving component 1530 as described with reference to FIG.

[0267]

[0248] The following provides an overview of aspects of the present disclosure.

[0268]

[0249] Aspect 1: A method for wireless communication in a UE, the method comprising: receiving at least one reference signal from a base station via a communication channel for wireless communication between the UE and the base station; determining a response of the communication channel based at least in part on the at least one reference signal received via the communication channel; and transmitting a message to the base station indicating a set of channel coefficients corresponding to a two-dimensional model representing the response, the two-dimensional model including a spatial model and a time domain response of the communication channel.

[0269]

[0250] Aspect 2: The method of aspect 1, further comprising determining a frequency domain response of the communication channel as part of determining the response, and generating a time domain response based at least in part on the frequency domain response of the communication channel.

[0270]

[0251] Aspect 3: The method of aspect 2, further comprising generating a spatial model based at least in part on a time domain response or a frequency domain response of the communication channel.

[0271]

[0252] Aspect 4: The method of any one of aspects 1 to 3, wherein the two-dimensional model is a Kronecker product of a matrix representation of the spatial model and a matrix representation of the time domain response of the communication channel.

[0272]

[0253] Aspect 5: The method of any of aspects 1 to 4, further comprising generating a set of channel coefficients based at least in part on a minimum mean squared error solution between the determined response and the two-dimensional model.

[0273]

[0254] Aspect 6: The method of any one of aspects 1 to 5, wherein the set of channel coefficients includes a set of quantized coefficients.

[0274]

[0255] Aspect 7: The method of any of aspects 1 to 6, further comprising generating a two-dimensional model based at least in part on one or more antennas at the UE, one or more antennas at the base station, or both.

[0275]

[0256] Aspect 8: The method of any one of aspects 1 to 7, wherein transmitting the message includes transmitting a set of bits indicating the set of channel coefficients to the base station via a control channel or a shared channel.

[0276]

[0257] Aspect 9: The method of aspect 8, further comprising: transmitting an indication of a number of quantization bits for the message to a base station based at least in part on a mean squared error or a signal-to-noise ratio of the communication channel.

[0277]

[0258] Aspect 10: A method according to any of aspects 1 to 9, further comprising: transmitting a set of channel coefficients in a first slot; and transmitting a set of differential channel coefficients in a second slot after the first slot, wherein each differential channel coefficient of the set of differential channel coefficients includes a channel coefficient difference with respect to a respective channel coefficient of the set of channel coefficients.

[0278]

[0259] Aspect 11: The method described in aspect 10, further comprising transmitting a second set of channel coefficients different from the set of channel coefficients in a third slot after the first slot, wherein the set of channel coefficients and the second set of channel coefficients are transmitted according to the first period.

[0279]

[0260] Aspect 12: The method of aspect 11, further comprising transmitting a second set of differential channel coefficients in a fourth slot after the second slot, wherein each differential channel coefficient of the second set of differential channel coefficients includes a channel coefficient difference relative to a respective channel coefficient of the set of channel coefficients or a respective differential channel coefficient of the set of differential channel coefficients, wherein the set of differential channel coefficients and the second set of differential channel coefficients are transmitted according to a second period different from the first period.

[0280]

[0261] Aspect 13: A method as described in any of aspects 10 to 12, further comprising receiving an instruction from a base station instructing the UE to enable transmission of a set of differential channel coefficients, wherein transmitting the set of differential channel coefficients is based at least in part on receiving the instruction.

[0281]

[0262] Aspect 14: A method according to any of aspects 10 to 13, further comprising receiving an instruction from a base station instructing the UE to use a differential encoding procedure based at least in part on the mobility of the UE or the time interval between a message indicating a set of channel coefficients and a previous message indicating a previous set of channel coefficients.

[0282]

[0263] Aspect 15: A method as described in any of aspects 1 to 14, further comprising receiving an indication of an ordering of the set of spatial domain basis functions from a base station, and generating a spatial model based at least in part on the ordering of the set of spatial domain basis functions.

[0283]

[0264] Aspect 16: The method of aspect 15, wherein the instructions include a configuration for the spatial model including a list of spatial domain basis functions, the list of spatial domain basis functions corresponding to an ordering of the set of spatial domain basis functions.

[0284]

[0265] Aspect 17: A method as described in any of aspects 1 to 16, further comprising receiving an indication of an ordering of the set of time domain basis functions from a base station, and generating a time domain response based at least in part on the ordering of the set of time domain basis functions.

[0285]

[0266] Aspect 18: The method of any of aspects 1-14, further comprising transmitting an indication of an ordering of the set of spatial domain basis functions, an ordering of the set of time domain basis functions, or both.

[0286]

[0267] Aspect 19: A method described in any of aspects 1 to 18, further comprising: determining a time domain response of a communication channel at multiple timings for each of multiple antenna port pairs as part of determining the response; selecting a set of time domain basis functions based at least in part on determining the time domain response of the communication channel at the multiple timings; and generating a time domain response based at least in part on the selected set of time domain basis functions.

[0287]

[0268] Aspect 20: The method of aspect 19, further comprising: for each timing of the plurality of timings, determining a cumulative energy of the time domain response across the plurality of antenna port pairs; and selecting a set of timings from the plurality of timings based at least in part on determining the cumulative energy of the time domain response for each timing of the plurality of timings, wherein selecting a set of time domain basis functions is based at least in part on the selected set of timings.

[0288]

[0269] Aspect 21: The method described in aspect 20, further comprising evaluating a mean squared error and a channel estimate of the determined response using a selected set of timings, wherein selecting a set of time-domain basis functions is based at least in part on evaluating the mean squared error.

[0289]

[0270] Aspect 22: A method as described in any of aspects 19 to 21, further comprising receiving an indication of a number of timings from a base station, wherein selecting a set of time-domain basis functions is based at least in part on the indicated number of timings.

[0290]

[0271] Aspect 23: The method of any one of aspects 19 to 21, further comprising transmitting, to a base station, an indication of some of the multiple timings.

[0291]

[0272] Aspect 24: A method described in any of aspects 1 to 23, further comprising receiving an indication of a set of antenna port pairs from a base station, determining a correlation between each antenna port pair in the set of antenna port pairs, the antenna port pair being associated with a UE or a base station, as part of determining the response, selecting a set of spatial domain basis functions based at least in part on determining the correlation between each antenna port pair in the set of antenna port pairs, and generating a spatial model based at least in part on the selected set of spatial domain basis functions.

[0292]

[0273] Aspect 25: The method of aspect 24, further comprising selecting a set of spatial domain basis functions based at least in part on a lowest determined correlation for an antenna port pair of the set of antenna port pairs.

[0293]

[0274] Aspect 26: The method described in aspect 24 or 25, further comprising evaluating a spatial autocorrelation matrix based at least in part on determining the correlation between each antenna port pair of the set of antenna port pairs, wherein selecting a set of spatial domain basis functions is based at least in part on the spatial autocorrelation matrix.

[0294]

[0275] Aspect 27: A method for wireless communication in a base station, the method comprising: transmitting at least one reference signal to the UE via a communication channel for wireless communication between the UE and the base station; and receiving a message from the UE indicating a set of channel coefficients corresponding to a two-dimensional model representing a response of the communication channel, the two-dimensional model including a spatial model and a time domain response of the communication channel.

[0295]

[0276] Aspect 28: The method of aspect 27, wherein the two-dimensional model is a Kronecker product of a matrix representation of the spatial model and a matrix representation of the time-domain response of the communication channel.

[0296]

[0277] Aspect 29: The method of aspect 27 or 28, wherein the set of channel coefficients includes a set of quantized coefficients.

[0297]

[0278] Aspect 30: The method of any of aspects 27 to 29, wherein receiving the message includes receiving a set of bits from the UE over a control channel or a shared channel, the set of channel coefficients being indicative of the set of channel coefficients.

[0298]

[0279] Aspect 31: The method of aspect 30, further comprising receiving from the UE an indication of a number of quantization bits for the message based at least in part on a mean squared error or a signal to noise ratio of the communication channel.

[0299]

[0280] Aspect 32: A method according to any of aspects 27 to 31, further comprising: receiving a set of channel coefficients in a first slot; and receiving a set of differential channel coefficients in a second slot after the first slot, wherein each differential channel coefficient of the set of differential channel coefficients includes a channel coefficient difference with respect to a respective channel coefficient of the set of channel coefficients.

[0300]

[0281] Aspect 33: The method described in aspect 32, further comprising receiving a second set of channel coefficients different from the set of channel coefficients at a third slot after the first slot, wherein the set of channel coefficients and the second set of channel coefficients are received according to the first period.

[0301]

[0282] Aspect 34: The method of aspect 33, further comprising receiving a second set of differential channel coefficients in a fourth slot after the second slot, wherein each differential channel coefficient of the second set of differential channel coefficients includes a channel coefficient difference relative to a respective channel coefficient of the set of channel coefficients or a respective differential channel coefficient of the set of differential channel coefficients, wherein the set of differential channel coefficients and the second set of differential channel coefficients are transmitted according to a second period different from the first period.

[0302]

[0283] Aspect 35: A method as described in any of aspects 32 to 34, further comprising sending an instruction to a UE instructing the UE to enable transmission of a set of differential channel coefficients, wherein receiving the set of differential channel coefficients is based at least in part on sending the instruction.

[0303]

[0284] Aspect 36: A method as described in any of aspects 32 to 35, further comprising sending an instruction to the UE instructing the UE to use a differential encoding procedure based at least in part on the mobility of the UE or the time interval between the message indicating the set of channel coefficients and a previous message indicating the previous set of channel coefficients.

[0304]

[0285] Example 37: The method of any one of examples 27 to 36, further comprising transmitting an indication of an ordering of the set of spatial domain basis functions for the two-dimensional model to the UE.

[0305]

[0286] Aspect 38: The method of aspect 37, wherein the instructions include a configuration for the spatial model including a list of spatial domain basis functions, the list of spatial domain basis functions corresponding to an ordering of the set of spatial domain basis functions.

[0306]

[0287] Example 39: The method of any one of examples 27 to 38, further comprising transmitting to the UE an indication of an ordering of the set of time-domain basis functions for the two-dimensional model.

[0307]

[0288] Aspect 40: A method according to any of aspects 27 to 35, further comprising receiving an indication of an ordering of a set of spatial domain basis functions, an ordering of a set of time domain basis functions, or both, for the two-dimensional model.

[0308]

[0289] Example 41: The method of any one of examples 27 to 40, further comprising transmitting, to the UE, some timing instructions for the two-dimensional model.

[0309]

[0290] Example 42: The method of any one of examples 27 to 40, further comprising receiving from the UE an indication of some of the timings for the two-dimensional model.

[0310]

[0291] Aspect 43: The method of any one of aspects 27 to 42, further comprising transmitting to the UE an indication of a set of antenna port pairs, each antenna port pair being associated with a UE or a base station.

[0311]

[0292] Aspect 44: An apparatus for wireless communication in a UE, comprising: a processor, a memory coupled to the processor, and instructions stored in the memory, the instructions being executable by the processor to cause the apparatus to perform a method described in any of aspects 1 to 26.

[0312]

[0293] Aspect 45: An apparatus for wireless communication in a UE, the apparatus including at least one means for performing a method according to any one of aspects 1 to 26.

[0313]

[0294] Aspect 46: A non-transitory computer-readable medium storing code for wireless communication in a UE, the code including instructions executable by a processor to perform a method described in any of aspects 1 to 26.

[0314]

[0295] Aspect 47: An apparatus for wireless communication in a base station, comprising: a processor, a memory coupled to the processor, and instructions stored in the memory, the instructions being executable by the processor to cause the apparatus to perform a method described in any of aspects 27 to 43.

[0315]

[0296] Aspect 48: An apparatus for wireless communication in a base station, comprising at least one means for performing the method according to any one of aspects 27 to 43.

[0316]

[0297] Aspect 49: A non-transitory computer-readable medium storing code for wireless communication in a base station, the code including instructions executable by a processor to perform a method described in any of aspects 27 to 43.

[0317]

[0298] It should be noted that the methods described herein are descriptions of possible implementations, that the acts and steps may be rearranged or otherwise modified, and that other implementations are possible. Furthermore, aspects from two or more of these methods may be combined.

[0318]

[0299] Although aspects of LTE, LTE-A, LTE-A Pro, or NR systems may be described as examples, and LTE, LTE-A, LTE-A Pro, or NR terminology may be used in much of the description, the techniques described herein may be applicable to other than LTE, LTE-A, LTE-A Pro, or NR networks. For example, the described techniques may be applicable to various other wireless communication systems, such as Ultra Mobile Broadband (UMB), Institute of Electrical and Electronics Engineers (IEEE) 802.11 (Wi-Fi), IEEE 802.16 (WiMAX), IEEE 802.20, Flash-OFDM, and other systems and radio technologies not explicitly mentioned herein.

[0319]

[0300] The information and signals described herein may be represented using any of a wide variety of technologies and techniques. For example, data, instructions, commands, information, signals, bits, symbols, and chips that may be referred to throughout the description may be represented by voltages, currents, electromagnetic waves, magnetic fields or particles, optical fields or particles, or any combination thereof.

[0320]

[0301] The various example blocks and components described with respect to the present disclosure herein may be implemented or performed using a general purpose processor, a DSP, an ASIC, a CPU, an FPGA or other programmable logic device, discrete gate or transistor logic, discrete hardware components, or any combination thereof designed to perform the functions described herein. A general purpose processor may be a microprocessor, but alternatively, the processor may be any processor, controller, microcontroller, or state machine. A processor may also be implemented as a combination of computing devices (e.g., a combination of a DSP and a microprocessor, multiple microprocessors, one or more microprocessors in conjunction with a DSP core, or any other such configuration).

[0321]

[0302] The functions described herein may be implemented in hardware, software executed by a processor, firmware, or any combination thereof. When implemented in software executed by a processor, the functions may be stored on or transmitted via a computer-readable medium as one or more instructions or codes. Other examples and implementations are within the scope of this disclosure and the appended claims. For example, due to the nature of software, the functions described herein may be implemented using software executed by a processor, hardware, firmware, hardwiring, or any combination thereof. Features implementing the functions may also be physically located in various locations, including being distributed such that parts of the functions are implemented in different physical locations.

[0322]

[0303] Computer-readable media includes both non-transitory computer storage media and communication media, including any medium that facilitates transfer of a computer program from one place to another. Non-transitory storage media may be any available medium that can be accessed by a general purpose or special purpose computer. By way of example and not limitation, non-transitory computer-readable media may include RAM, ROM, electrically erasable programmable ROM (EEPROM), flash memory, compact disk (CD) ROM or other optical disk storage, magnetic disk storage or other magnetic storage devices, or any other non-transitory medium that can be used to carry or store desired program code means in the form of instructions or data structures and that can be accessed by a general purpose or special purpose computer or a general purpose or special purpose processor. Also, any connection is properly termed a computer-readable medium. For example, if the software is transmitted from a website, server, or other remote source using coaxial cable, fiber optic cable, twisted pair, digital subscriber line (DSL), or wireless technologies such as infrared, radio, and microwave, the coaxial cable, fiber optic cable, twisted pair, DSL, or wireless technologies such as infrared, radio, and microwave are included within the definition of computer readable media. As used herein, disk and disc include CDs, laser discs, optical discs, digital versatile discs (DVDs), floppy disks, and Blu-ray discs, where disks typically reproduce data magnetically and discs reproduce data optically using lasers. Combinations of the above are also included within the scope of computer readable media.

[0323]

[0304] As used herein, including within the claims, "or" as used in a list of items (e.g., a list of items followed by a phrase such as "at least one of" or "one or more of") indicates an inclusive list, such as, for example, a list of at least one of A, B, or C means A or B or C or AB or AC or BC or ABC (i.e., A and B and C). Also, the phrase "based on" as used herein should not be construed as a reference to a closed set of conditions. For example, an exemplary step described as "based on condition A" may be based on both condition A and condition B without departing from the scope of the present disclosure. In other words, as used herein, the phrase "based on" is to be interpreted the same as the phrase "based at least in part on."

[0324]

[0305] The terms "determine" or "determining" encompass a wide variety of actions, and thus "determining" can include calculating, computing, processing, deriving, investigating, looking up (e.g., via a lookup in a table, database, or another data structure), ascertaining, and the like. "Determining" can also include receiving (e.g., receiving information), accessing (e.g., accessing data in a memory), and the like. "Determining" can also include resolving, selecting, choosing, establishing, and other similar acts.

[0325]

[0306] In the accompanying figures, similar components or features may have the same reference label. Furthermore, various components of the same type may be distinguished by following the reference label with a dash and a second label that distinguishes the similar components. If only a first reference label is used in this specification, the description is applicable to any of the similar components having the same first reference label, regardless of the second reference label, or any other subsequent reference label.

[0326]

[0307] The description given herein with respect to the attached drawings describes an exemplary configuration and does not necessarily represent all examples that may be implemented or fall within the scope of the claims. The term "example" as used herein means "serving as an example, instance, or illustration" and does not mean "preferred" or "advantageous over other examples." The detailed description includes specific details for the purposes of providing an understanding of the described techniques. However, these techniques may be practiced without these specific details. In some instances, known structures and devices are shown in block diagram form to avoid obscuring the concepts of the described examples.

[0327]

[0308] The description in this specification is provided to enable a person skilled in the art to make or use the present disclosure. Various modifications of the present disclosure will be apparent to those skilled in the art, and the general principles defined in this specification may be applied to other variations without departing from the scope of the present disclosure. Thus, the present disclosure is not limited to the examples and designs described in this specification, but should be accorded the widest scope consistent with the principles and novel features disclosed in this specification.

Claims

1. 1. A method for wireless communication in a user equipment (UE), comprising: receiving at least one reference signal from a base station over a communication channel for wireless communication between the UE and the base station; determining a response of the communication channel based at least in part on the at least one reference signal received over the communication channel; transmitting a message to the base station indicating a set of channel coefficients corresponding to a two-dimensional model representing the response, the two-dimensional model including a spatial model and a time domain response of the communication channel; wherein the two-dimensional model is a Kronecker product of a matrix representation of the spatial model and a matrix representation of the time-domain response of the communication channel.

2. determining a frequency domain response of the communication channel as part of determining the response; generating the time domain response based at least in part on the frequency domain response of the communication channel; The method of claim 1 further comprising:

3. generating the spatial model based at least in part on the time domain response or the frequency domain response of the communication channel; or The method of claim 2 , further comprising generating the set of channel coefficients based at least in part on a minimum mean square error solution between the determined response and the two-dimensional model.

4. the set of channel coefficients comprises a set of quantized coefficients; or The method of claim 1 , further comprising generating the two-dimensional model based at least in part on one or more antennas at the UE, one or more antennas at the base station, or both.

5. sending the message, transmitting a set of bits indicative of the set of channel coefficients to the base station over a control channel or a shared channel; 10. The method of claim 1, further comprising: transmitting to the base station an indication of a number of quantization bits for the message based at least in part on a mean squared error or a signal-to-noise ratio of the communication channel.

6. receiving an indication of an ordering of a set of spatial domain basis functions from the base station; generating the spatial model based at least in part on the ordering of the set of spatial domain basis functions; Further comprising: the instructions include a configuration for the spatial model including a list of spatial domain basis functions; the list of spatial domain basis functions corresponds to the ordering of the set of spatial domain basis functions. The method of claim 1.

7. receiving an indication of an ordering of a set of time-domain basis functions from the base station; generating the time-domain response based at least in part on the ordering of the set of time-domain basis functions; or The method of claim 1 , further comprising transmitting an indication of an ordering of the set of spatial domain basis functions, an ordering of the set of time domain basis functions, or both.

8. determining the time domain response of the communication channel at a plurality of times for each of a plurality of antenna port pairs as part of determining the response; selecting a set of time-domain basis functions based at least in part on determining the time-domain response of the communication channel at the plurality of times; generating the time-domain response based at least in part on the selected set of time-domain basis functions; or receiving an indication of a set of antenna port pairs from the base station; determining a correlation between each antenna port pair of the set of antenna port pairs, the antenna port pair associated with the UE or the base station, as part of determining the response; selecting a set of spatial domain basis functions based at least in part on determining the correlation between each antenna port pair of the set of antenna port pairs; generating the spatial model based at least in part on the selected set of spatial domain basis functions; The method of claim 1 further comprising:

9. 1. A method for wireless communication in a base station, comprising: transmitting at least one reference signal to a user equipment (UE) over a communication channel for wireless communication between the UE and the base station; receiving from the UE a message indicating a set of channel coefficients corresponding to a two-dimensional model representing a response of the communication channel, the two-dimensional model including a spatial model and a time domain response of the communication channel; wherein the two-dimensional model is a Kronecker product of a matrix representation of the spatial model and a matrix representation of the time-domain response of the communication channel.

10. the set of channel coefficients comprises a set of quantized coefficients; or receiving the message, receiving a set of bits from the UE over a control channel or a shared channel, the set of bits indicating the set of channel coefficients; 10. The method of claim 9, further comprising receiving from the UE an indication of a number of quantization bits for the message based at least in part on a mean squared error or signal to noise ratio of the communication channel.

11. transmitting to the UE an indication of an ordering of a set of spatial-domain basis functions for the two-dimensional model; the instructions include a configuration for the spatial model including a list of spatial domain basis functions; the list of spatial domain basis functions corresponds to the ordering of the set of spatial domain basis functions; or The method of claim 9 , further comprising: transmitting to the UE an indication of an ordering of a set of time-domain basis functions for the two-dimensional model.

12. receiving an indication of an ordering of a set of spatial domain basis functions, an ordering of a set of time domain basis functions, or both, for the two-dimensional model; or The method of claim 9 , further comprising transmitting to the UE certain timing instructions for the two-dimensional model.

13. receiving from the UE an indication of some of a plurality of timings for the two-dimensional model; or 10. The method of claim 9, further comprising: transmitting to the UE an indication of a set of antenna port pairs, each antenna port pair being associated with the UE or the base station.

14. A user equipment (UE), comprising: means for receiving at least one reference signal from the base station over a communication channel for wireless communication between the UE and the base station; means for determining a response of the communication channel based at least in part on the at least one reference signal received over the communication channel; means for transmitting to the base station a message indicating a set of channel coefficients corresponding to a two-dimensional model representing the response, the two-dimensional model including a spatial model and a time domain response of the communication channel; wherein the two-dimensional model is a Kronecker product of a matrix representation of the spatial model and a matrix representation of the time-domain response of the communication channel.

15. A base station, means for transmitting at least one reference signal to the UE over a communication channel for wireless communication between the UE and the base station; means for receiving from the UE a message indicating a set of channel coefficients corresponding to a two-dimensional model representing a response of the communication channel, the two-dimensional model including a spatial model and a time domain response of the communication channel; wherein the two-dimensional model is a Kronecker product of a matrix representation of the spatial model and a matrix representation of the time domain response of the communication channel.

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