CN112205049A

CN112205049A - Channel state information feedback

Info

Publication number: CN112205049A
Application number: CN201880094048.XA
Authority: CN
Inventors: 刘皓; 郝金平; R·阿梅德; K·S·J·拉杜; F·福克; W·J·希勒里; 毛小矛; E·维索特斯基
Original assignee: Nokia Shanghai Bell Co Ltd; Nokia Networks Oy
Current assignee: Nokia Shanghai Bell Co Ltd; Nokia Oyj
Priority date: 2018-05-31
Filing date: 2018-05-31
Publication date: 2021-01-08
Anticipated expiration: 2038-05-31
Also published as: WO2019227403A1; CN112205049B

Abstract

Various communication systems may benefit from channel state information feedback. For example, it may be helpful to use time or frequency compression to improve channel state information feedback. According to some embodiments, a method may comprise: determining, at the user equipment, a set of supported channels based on at least one of the first condition or the second condition. The first condition may include the selected channel support number being greater than or equal to the configured channel support number. The second condition may include a variance of the residual matrix being less than or equal to a threshold variance. The method may further comprise: after determining that at least one of the first condition or the second condition has been met, a channel state information report including a set of channel support indices is sent from the user equipment to the network entity based on the set of supported channels.

Description

Channel state information feedback

Technical Field

Various communication systems may benefit from channel state information feedback. For example, it may be helpful to use time or frequency compression to improve channel state information feedback.

Background

In third generation partnership project (3GPP) technologies, such as Long Term Evolution (LTE), fifth generation (5G), or New Radio (NR) technologies, Multiple Input Multiple Output (MIMO) may be utilized to help facilitate signaling. MIMO is used to increase the overall bit rate by transmitting two or more different data streams on two or more different antennas, using the same resources in frequency or time, and separating them only by using different reference signals. In NR techniques, the number of antennas and/or data streams will increase, thereby simultaneously increasing the importance of MIMO.

To allow MIMO to be used in NR techniques, channel state information feedback and compression schemes are used. For example, time, frequency, and/or spatial domain compression is used to compress the signal transmission. This may allow multiple signals to be transmitted on multiple antennas using the same frequency and/or time resources.

Disclosure of Invention

According to certain embodiments, an apparatus may include at least one memory including computer program code and at least one processor. The at least one memory and the computer program code may, with the at least one processor, be configured to cause the apparatus at least to: a set of supported channels is determined based on at least one of the first condition or the second condition. The first condition may include the selected channel support number being greater than or equal to the configured channel support number. The second condition may include a variance of the residual matrix being less than or equal to a threshold variance. The at least one memory and the computer program code may also be configured to, with the at least one processor, cause the apparatus at least to: after determining that at least one of the first condition or the second condition has been met, sending a channel state information report including a set of channel support indices to a network entity based on the set of supported channels.

According to some embodiments, a method may comprise: determining, at the user equipment, a set of supported channels based on at least one of the first condition or the second condition. The first condition may include the selected channel support number being greater than or equal to the configured channel support number. The second condition may include a variance of the residual matrix being less than or equal to a threshold variance. The method may further comprise: after determining that at least one of the first condition or the second condition has been met, a channel state information report including a set of channel support indices is sent from the user equipment to the network entity based on the set of supported channels.

In some embodiments, an apparatus may comprise: means for determining a set of supported channels based on at least one of the first condition or the second condition. The first condition may include the selected channel support number being greater than or equal to the configured channel support number. The second condition may include a variance of the residual matrix being less than or equal to a threshold variance. The apparatus may further comprise means for: after determining that at least one of the first condition or the second condition has been met, sending a channel state information report including a set of channel support indices to a network entity based on the set of supported channels.

According to certain embodiments, a non-transitory computer-readable medium encodes instructions that, when executed in hardware, perform a process. The process may include: determining, at the user equipment, a set of supported channels based on at least one of the first condition or the second condition. The first condition may include the selected channel support number being greater than or equal to the configured channel support number. The second condition may include a variance of the residual matrix being less than or equal to a threshold variance. The process may further include: after determining that at least one of the first condition or the second condition has been met, a channel state information report including a set of channel support indices is sent from the user equipment to the network entity based on the set of supported channels.

According to some other embodiments, a computer program product may encode instructions for performing a process. The process may include determining, at the user equipment, a set of supported channels based on at least one of the first condition or the second condition. The first condition may include the selected channel support number being greater than or equal to the configured channel support number. The second condition may include a variance of the residual matrix being less than or equal to a threshold variance. The process may further include: after determining that at least one of the first condition or the second condition has been met, a channel state information report including a set of channel support indices is sent from the user equipment to the network entity based on the set of supported channels.

According to some embodiments, an apparatus may comprise: circuitry for determining a set of supported channels based on at least one of a first condition and a second condition. The first condition may include the selected channel support number being greater than or equal to the configured channel support number. The second condition may include a variance of the residual matrix being less than or equal to a threshold variance. The apparatus may also include circuitry to: after determining that at least one of the first condition or the second condition has been met, sending a channel state information report including a set of channel support indices to a network entity based on the set of supported channels.

According to certain embodiments, an apparatus may include at least one memory including computer program code and at least one processor. The at least one memory and the computer program code may be configured to, with the at least one processor, cause the apparatus at least to: after determining that at least one of the first condition or the second condition is satisfied, receiving a channel state information report including a set of channel support indices from the user equipment based on the set of supported channels. The first condition may include the selected channel support number being greater than or equal to the configured channel support number. The second condition may include a variance of the residual matrix being less than or equal to a threshold variance. The at least one memory and the computer program code may also be configured to, with the at least one processor, cause the apparatus at least to: the channel state matrix is constructed based on a set of channel support indices included in the channel state information report.

According to some embodiments, a method may comprise: after at least one of the first condition or the second condition is satisfied, a channel state information report including a set of channel support indices is received at the network entity from the user equipment based on the set of supported channels. The first condition may include the selected channel support number being greater than or equal to the configured channel support number. The second condition may include a variance of the residual matrix being less than or equal to a threshold variance. The method may further comprise: the channel state matrix is constructed based on a set of channel support indices included in the channel state information report.

In certain embodiments, an apparatus may include means for: receiving a channel state information report including a set of channel support indices from the user equipment based on the set of supported channels after at least one of the first condition or the second condition is satisfied. The first condition may include the selected channel support number being greater than or equal to the configured channel support number. The second condition may include a variance of the residual matrix being less than or equal to a threshold variance. The apparatus may also include means for constructing a channel state matrix based on a set of channel support indices included in a channel state information report.

According to certain embodiments, a non-transitory computer-readable medium encodes instructions that, when executed in hardware, perform a process. The process may include: after at least one of the first condition or the second condition is satisfied, a channel state information report including a set of channel support indices is received at the network entity from the user equipment based on the set of supported channels. The first condition may include the selected channel support number being greater than or equal to the configured channel support number. The second condition may include a variance of the residual matrix being less than or equal to a threshold variance. The process may further include: the channel state matrix is constructed based on a set of channel support indices included in the channel state information report.

According to some other embodiments, a computer program product may encode instructions for performing a process. The process may include: after at least one of the first condition and the second condition is satisfied, a channel state information report including a set of channel support indices is received at the network entity from the user equipment based on the set of supported channels. The first condition may include the selected channel support number being greater than or equal to the configured channel support number. The second condition may include a variance of the residual matrix being less than or equal to a threshold variance. The process may further include: the channel state matrix is constructed based on a set of channel support indices included in the channel state information report.

According to some embodiments, an apparatus may include circuitry to: receiving a channel state information report including a set of channel support indices from the user equipment based on the set of supported channels after at least one of the first condition or the second condition is satisfied. The first condition may include the selected channel support number being greater than or equal to the configured channel support number. The second condition may include a variance of the residual matrix being less than or equal to a threshold variance. The apparatus may also include circuitry for constructing a channel state matrix based on a set of channel support indices included in a channel state information report.

Drawings

For a proper understanding of example embodiments of the present invention, reference should be made to the accompanying drawings, in which:

FIG. 1 illustrates an example of a table according to some embodiments.

FIG. 2 illustrates an example of a graph in accordance with certain embodiments.

FIG. 3 illustrates an example of a method according to some embodiments.

FIG. 4 illustrates an example of a method according to some embodiments.

FIG. 5 illustrates an example of a system according to some embodiments.

Detailed Description

Certain embodiments allow for reduced overhead by enhancing channel state information feedback. In particular, certain embodiments provide for using finer granularity and feedback. Feedback granularity and accuracy may allow, for example, improved channel state information feedback at the sub-band level. In addition, certain embodiments may help improve overall system or network performance, thereby reducing overhead associated with channel state information feedback.

Channel state information feedback may be sent from the user equipment to the network entity. The network entity may be, for example, a 5G or NR NodeB (gNB). Channel state information feedback may be based on an Orthogonal Matching Pursuit (OMP) algorithm of Compressed Sensing (CS), which may utilize time domain channel compression techniques. For example, the OMP algorithm may be a sparse approximation, involving finding the best matching projection of multidimensional data over a dictionary (dictionary) span. The dictionary may be a collection of unit norm basic building blocks of the signal space. The unit norm vector may be referred to as an atom (atom). A dictionary may be complete if its atoms span the entire signal space. When using OMP, the extracted coefficients can be updated by computing the orthogonal projection of the signal on the set of atoms.

In some embodiments, common channel support may speed up the convergence of OMP. The channel support may be a position of a time domain channel tap in a Channel Impulse Response (CIR) and may be related to a power delay profile (profile). In the 5G or NR technique, co-located transmit or receive antennas and/or transmit or receive beams formed by co-located transmit or receive antennas may share the same main tap. In some embodiments, the main tap may be referred to as a supported channel.

In some embodiments, the frequency domain channel matrix H may be obtained across channel state information reference signal measurements_FD。H_FDMay have N_fxN_pSize of (1), wherein N_fIs the number of active subcarriers, and N_pIs the number of transmit antenna ports multiplied by the number of receive antenna ports. Can be determined according to the following equation:

will be the frequency domain channel matrix H_FDCompressed into a new matrix H_TDReferred to as the compressed time domain channel matrix. H_TDMay have N_txN_pOf smaller size, wherein N_tMay be less than the number N of active subcarriers_f。

May be a linear transformation matrix comprising N_tA Discrete Fourier Transform (DFT) vector column of the individual main taps.

The main tap may be selected based on time domain compression, such as OMP. In some embodiments, the initial residual matrix R₀＝H_FDCan have a tap index set

DFT matrix including selected taps with iteration counter l equal to 0

And candidate set C₀＝{1，2，...，N_f}. The measurement matrix Φ may be defined to have, for example, a dimension N_f×N_fDimensioned to be built to size N using the available channel frequency response_fft×N_fftOf DFT matrix, where N_fftIs the number of whole sub-carriers. The rows of Φ may correspond to the locations of the active subcarriers, and the columns of Φ may correspond to the channel support ranges. Then, can be based onThe following equation:

increment l and find tap index lambda_lWherein

Is R_l-1Is the ith column and

is the DFT vector (one column in the measurement matrix Φ) for tap j. The following can then be done according to the equation: lambda_l＝Λ_l-1∪{λ_lAnd

to augment the set of tap indices and DFT matrix of the chosen taps. A new signal estimate X can be obtained_l＝Φ_l ^HH_FDAnd a new residual matrix R can be calculated_l＝H_FD-Φ_lX_l. Candidate set C_l＝C_l-1/{λ_lIt can be updated, where the operator "/" denotes the element λ_lFrom the set C_l-1Is removed. l may be incremented and at some criteria (such as l < N)_τOr a projected Mean Square Error (MSE) rule) is met, the tap index λ can be found_l。

The channel state information feedback signaling may be based on time domain compression (such as OMP). For example, the channel state information may include a selected set of tap indices Λ, where the set of tap indices may be channel support for a given transmission. Alternatively or additionally, the channel state information may comprise a compressed time domain channel matrix H_TDThe coefficient of (a). In some embodiments, one or more higher layer parameters may be configured using Radio Resource Control (RRC).

In some embodiments, the selection of the set of tap indices may be performed after at least one of two different conditions is met or satisfied. The taps may also be referred to as channel support. The first condition may be, for example, the selected supported tapsThe number is greater than or equal to the configured number of supported taps. For example, the number of supported taps configured may be the maximum. For example, the number of taps N selected_tapNot less than the number of taps N configured_t. The configured number of taps N may be received at the user equipment from a network entity_t. In some other embodiments, the number of taps N configured may be preconfigured based on the user equipment class_t. The second condition may be that the variance of the residual matrix is less than or equal to a threshold variance. For example, residual matrix R_lMay not be greater than a threshold variance, such as the channel matrix H_FDIs multiplied by a threshold factor alpha, where alpha ∈ [0, 1 ]]. The user equipment may receive the threshold factor a from the network entity. In other words, | R_l||²≤α||H_FD||². Using at least one of the above two conditions as a selection criterion may help to reduce feedback overhead while also ensuring that the main tap is selected for each user equipment.

In some embodiments, the number of channels selected to support (also referred to as N)_tap) May be less than the configured number of taps N for certain user equipments_t. For N_pA set of paired transmit and receive antenna ports, tap indices

May be public. The tap index set may be compared with

Joint coding of bits, from N_fSelecting N of candidate taps_tapA main tap. Accordingly, a channel state information report including a channel support index set may be transmitted with a longer feedback periodicity. In some embodiments, the set of channel support indices may have a feedback period longer than the coefficients of the compressed time domain channel. The set of channel support indices may be based on the selected channel support.

In some embodiments, a set of tap indices may be used

The bits are encoded separately. In some embodiments, joint coding may be used instead of separate coding in order to reduce feedback overhead. For example, assume N _f600 and N_tapJoint coding can reduce the channel state information payload by 26% compared to separate coding alone, 8.

In some embodiments, the feedback may include a time-compressed matrix H_TDOne or more coefficients of (a). Compressed matrix

Having N_tap×N_pA coefficient of, wherein

Can be selected from N_tap×N_pThe strongest coefficient is selected from the individual coefficients and its index can be quantized to

In other words, the strongest coefficients of the compressed time-domain channel matrix may be determined. The index of the strongest coefficient may then be quantized and the quantized index may be included in the transmitted channel state information report.

In some embodiments, the amplitude and/or phase of the strongest coefficient may be quantized. In some embodiments, the amplitude and phase of all other coefficients, except the strongest coefficient, may also be quantized. The quantized amplitude and phase may also be reported from the user equipment to a network entity, such as the gNB, as part of a channel state information report. The network entity may reconstruct the entire channel information using the quantized amplitude and phase. For example, the amplitude and phase may be used to reconstruct a channel matrix H that includes slow fading channel information and fast fading channel information_FD. Can also use H_TDAnd/or

To reconstruct the channel matrix.

In some embodiments, the magnitude value of the strongest coefficient may be quantized based on a Reference Signal Received Power (RSRP) of the user equipment. For example, the amplitude value may be 10 × log10 (Amp)²RSRP), where Amp may be the magnitude of the strongest coefficient and RSRP may be the RSRP value reported by the user equipment during a longer feedback duration or a longer feedback periodicity. In some embodiments, the ratio may be reported similar to a Channel Quality Indication (CQI) level with a 4-bit quantization level or any other value of quantization level. The magnitude of the strongest coefficients of different user equipment may have a very wide dynamic range. Therefore, direct quantization of the amplitude may cause a large feedback overhead. However, amplitude quantization using the above ratio may be an effective way to provide feedback for the strongest coefficients that minimize feedback overhead.

The compressed matrix H may be compressed_TDOther than the strongest coefficient (N)_tap×N_p-1) coefficients are divided by the strongest coefficients and then quantized separately according to amplitude and phase. In certain embodiments, the time-compressed matrix H_TDThe strongest coefficient of (N) and others_tap×N_p-1) coefficients can be reported separately. The user equipment may report the strongest coefficient or other coefficients to the network entity, e.g., on a Physical Uplink Shared Channel (PUSCH).

In some embodiments, the user equipment may receive a signal comprising one or more higher layer parameters from a network entity. One or more higher layer parameters may be configured in advance or statically or semi-statically before sending the channel state information report. The one or more higher layer parameters may include at least one of: number of main taps N_tThreshold factor a, and/or DFT matrix configuration with or without oversampling or subsampling. The DFT matrix may include N each_fA plurality of DFT column vectors of elements. Oversampling may mean that the number of DFT vectors is larger than the value N_fAnd subsampling may mean that the number of DFT vectors is less than the value N_fOtherwise the number may be equal to N_f. The quantization set and/or the quantization bits of amplitude and phase may be dividedConfigured as the strongest coefficient and other coefficients. Some embodiments described above may help improve system performance while also providing finer frequency granularity and higher feedback accuracy.

A network entity (such as a gNB) may receive a channel state information report from a user equipment. The channel state information may be received using the selected channel support number. The network entity may reconstruct or construct the channel state matrix based on the channel state information included in the channel state information report. In some embodiments, for example, the following equation may be used:

to recover the channel state matrix.

FIG. 1 illustrates an example of a table according to some embodiments. In particular, fig. 1 illustrates an example of payload statistics for channel state information feedback, in accordance with some embodiments. The number of transmit antenna ports may be 16, where (N)₁，N₂) (4, 2). For example, the number of receive antenna ports may be 2, and the number of active subcarriers may be N_fThe threshold factor may be α ═ 0.1, and the size of the DFT matrix may be 600 × 600. Compressed matrix H_TDMay have 4-bit phase quantization and 4-bit amplitude quantization, and a compressed matrix H_TDMay have 4-bit phase quantization and 3-bit amplitude quantization.

The number of main taps N, as shown in FIG. 1_t110 may be set to 2, 5, and 10. The number of taps N selected is based on the statistics shown in FIG. 1_tapMay be generally less than N_tWherein the mean or average number of selected taps is 1.9, 4.3, and 7.1 for different numbers of configured taps of 2, 5, and 10, respectively. Fig. 1 also shows tap feedback 120, including tap indication and tap selection, and strongest coefficients 130, including index, amplitude, and phase. In addition, fig. 1 shows the amplitude or phase of the other coefficients 140. The total payload for the configured

tap numbers

2, 5, and 10 may be equal to the total payload of 451, 1014, and 1662, respectively. Thus, in some implementationsIn an example, the total payload may increase as the number of taps configured increases. In other words, the channel state information feedback overhead increases as the number of channel supports increases.

FIG. 2 illustrates an example of a graph in accordance with certain embodiments. In particular, fig. 2 shows that the channel state information payload of XYZ type 210 may be 425 bits. On the other hand, explicit channel state information 220 may have total payloads configured with taps of 2 and 451 bits, while explicit channel state information 230 may have total payloads configured with taps of 5 and 1014 bits. The explicit channel state information 240 may have a total payload with taps configured of 10 and 1662 bits.

Certain embodiments utilizing explicit channel state information feedback and/or frequency compression may result in significant improvements in system performance when increasing the number of taps configured. In other words, using finer frequency granularity and higher feedback accuracy may help improve system performance.

In particular, as shown in fig. 1-2, some embodiments may have explicit channel state information with taps configured at 2, 5, and 10. The cell average Spectral Efficiency (SE) bits per second (bps)/hertz (Hz) may be 3.86, 4.38, and 4.50, corresponding to the number of taps configured, 2, 5, and 10. For the configured taps of 2, 5, and 10, the 5% cell edge SE may be 0.066bps/Hz, 0.071bps/Hz, and 0.072bps/Hz, respectively. Thus, the average cell SE percentage increase caused by some embodiments described above may be 12%, 27% and 31% for configured taps of 2, 5 and 10 on XYZ-type channel state information, respectively. On the other hand, the percentage increase in cell edge SE gain caused by some embodiments described above may be 5%, 13%, and 14%, respectively, for configured 2, 5, and 10 on XYZ-type channel state information.

FIG. 3 illustrates an example of a method according to some embodiments. In particular, fig. 3 illustrates a method performed by a user equipment. In step 310, the user equipment may receive a signal comprising one or more higher layer parameters from a network entity. The one or more higher layer parameters may be a configured number of channel supports, a threshold factor, a discrete fourier transform matrix configuration with or without oversampling or subsampling, a set of quantized indices, and/or quantized bits of the amplitude and phase of the strongest coefficient or other coefficients. The channels supported or channel support may be referred to as taps. In some embodiments, the signal may be an RRC signal. One or more layer parameters may be statically or semi-statically configured.

In step 320, the user equipment may determine a supported set of channels based on at least one of the first condition or the second condition. The first condition may include the selected channel support number being greater than or equal to the configured channel support number. The second condition may include a variance of the residual matrix being less than or equal to a threshold variance. For example, the configured number of supported channels may be received at the user equipment in step 310. For example, the threshold variance may depend on the variance of the channel matrix that may be received by the user equipment in step 310 and a threshold factor. In some embodiments, the selected number of channel supports may be greater than or equal to the configured number of channel supports, and at the same time the variance of the residual matrix may be less than or equal to the threshold variance.

In step 330, the user equipment may determine the strongest coefficients of the compressed time domain channel matrix. The user equipment may quantize the index of the strongest coefficient of the compressed time-domain channel matrix. The quantized index may be included in the transmitted channel state information report. Alternatively or additionally, the user equipment may quantize the amplitude and phase of at least one of the strongest coefficients or other coefficients of the compressed time domain channel matrix, as shown in step 340. The quantized amplitude and phase may be included in the transmitted channel state information report. For example, the magnitude of the strongest coefficient may be quantized based on a ratio of the magnitude to a reference signal received power of the user equipment.

In step 350, the user equipment may send a channel state information report including a set of channel support indices to the network entity based on the set of supported channels after determining that at least one of the first condition and the second condition has been satisfied. The set of channel support indices may be common to one or more pairs of transmit and receive antenna ports. In some other embodiments, the channel state information report may also include a quantized index of the strongest coefficient of the compressed time-domain channel matrix and/or a quantized amplitude and phase of the strongest coefficient or at least one of the other coefficients.

FIG. 4 illustrates an example of a method according to some embodiments. In particular, fig. 4 illustrates a method performed by a network entity (e.g., a gNB). The network entity shown in fig. 4 may communicate with the user equipment shown in fig. 3. In step 410, the network entity may send a signal including one or more higher layer parameters to the user equipment. The one or more higher layer parameters may include at least one of: the configured channel supports a number, a threshold factor, or a discrete fourier transform matrix configuration, a set of quantized indices, and/or quantized bits of the amplitude and phase of the strongest coefficient or other coefficients. The signal may be, for example, an RRC signal. One or more higher layer parameters may be statically or semi-statically configured.

In step 420, the network entity receives a channel state information report including a set of channel support indices from the user equipment based on the set of supported channels after at least one of the first condition or the second condition is satisfied. The first condition may include the selected channel support number being greater than or equal to the configured channel support number. The second condition may include a variance of the residual matrix being less than or equal to a threshold variance. In some embodiments, the set of channel support indices may be common to one or more pairs of transmit and receive antenna ports.

In step 430, the network entity may receive a quantized index of the strongest coefficient of the compressed time-domain channel matrix in the channel state information report from the user equipment. In step 440, the network entity may receive from the user equipment the quantized amplitude and phase of at least one of the strongest coefficient or other coefficients of the compressed time domain channel matrix in the channel state information report. In step 450, the network entity may reconstruct or construct a channel state matrix based on the set of channel support indices included in the channel state information report. In some other embodiments, the channel state matrix may be reconstructed or constructed based on at least one of: a quantized index of a strongest coefficient of the compressed time-domain channel matrix and/or a quantized amplitude and phase of the strongest coefficient or at least one of the other coefficients.

FIG. 5 illustrates a system according to some embodiments. It should be understood that each signal or block in fig. 1-4 may be implemented by various means, such as hardware, software, firmware, one or more processors, and/or circuitry, or a combination thereof. In one embodiment, the system may include a plurality of devices, such as, for example, a network entity 520 or a User Equipment (UE) 510. The system may include more than one UE 510 and more than one network entity 520. The network entity 520 may be a network node, base station, access point, access node, gNB, eNodeB (eNB), server, host, or any other network entity that may communicate with a UE.

Each of these devices may comprise at least one processor or control unit or module, denoted 511 and 521, respectively. At least one memory may be provided in each device and is denoted 512 and 522, respectively. The memory may include computer program instructions or computer code embodied therein. One or

more transceivers

513 and 523 may be provided, and each device may also include an antenna, shown as 514 and 524, respectively. Although only one antenna is shown for each, many antennas and multiple antenna elements may be provided for each device. For example, other configurations of these devices may be provided. For example, in addition to wireless communication, network entity 520 and UE 510 may additionally be configured for wired communication, and in

such cases antennas

514 and 524 may illustrate any form of communication hardware, and are not limited to only antennas.

The

transceivers

513 and 523 may each independently be a transmitter, a receiver, or both a transmitter and a receiver, or may be configured as a unit or device for transmission and reception. The transmitter and/or receiver (in the case of a radio) may also be implemented as a remote radio head, which is not located in the device itself, for example in the mast. Operations and functions may be performed in different entities, such as nodes, hosts or servers, in a flexible manner. In other words, the division of labor may vary from case to case. One possible use is for a network entity to deliver local content. One or more functions may also be implemented as virtual application(s) in software that may run on a server.

The user equipment or UE 510 may be a Mobile Station (MS), such as a mobile phone or smartphone or multimedia device, an IoT cellular device, a computer provided with wireless communication capabilities, such as a tablet, a personal data or digital assistant (PDA) provided with wireless communication capabilities, a portable media player, a digital camera, a camcorder, a navigation unit provided with wireless communication capabilities, or any combination thereof. In other embodiments, the user device may be replaced by a machine communication device (such as a sensor, meter, or robot) that does not require any human interaction.

In some embodiments, an apparatus (such as a user equipment or a network entity) may comprise means for performing the embodiments described above with respect to fig. 1-4. In certain embodiments, the at least one memory including the computer program code may be configured, with the at least one processor, to cause the apparatus at least to perform any of the processes described herein.

Processors

511 and 521 may be embodied by any computing or data processing device, such as a Central Processing Unit (CPU), Digital Signal Processor (DSP), Application Specific Integrated Circuit (ASIC), Programmable Logic Device (PLD), Field Programmable Gate Array (FPGA), digital enhancement circuitry, or the like, or a combination thereof. The processor may be implemented as a single controller, or as multiple controllers or processors.

For firmware or software, the implementation may include at least one module or unit (e.g., procedure, function, etc.) of a chipset.

Memories

512 and 522 may independently be any suitable storage device, such as a non-transitory computer-readable medium. A Hard Disk Drive (HDD), Random Access Memory (RAM), flash memory, or other suitable memory may be used. The memory may be combined on a single integrated circuit as the processor, or may be separate therefrom. Furthermore, the computer program instructions may be stored in a memory and processed by a processor, and may be in any suitable form of computer program code, such as a compiled or interpreted computer program written in any suitable programming language. The memory or data storage entity is typically internal, but may also be external or a combination thereof, such as in the case where additional storage capacity is obtained from a service provider. The memory may be fixed or removable.

The memory and computer program instructions may be configured, with the processor for a particular apparatus, to cause a hardware device, such as the network entity 520 or the UE 510, to perform any of the processes described above (e.g., see fig. 1-4). Thus, in certain embodiments, a non-transitory computer readable medium may be encoded with computer instructions or one or more computer programs (such as added or updated software routines, applets, or macros) that, when executed in hardware, may perform a process such as one of the processes described herein. The computer program may be coded by a programming language, which may be a high-level programming language, such as objective-C, C, C + +, C #, Java, etc., or a low-level programming language, such as a machine language or assembler. Alternatively, some embodiments may be implemented entirely in hardware.

In some embodiments, an apparatus may include circuitry configured to perform any of the processes or functions shown in fig. 1-4. In one example, the circuitry may be a purely hardware circuit implementation, such as analog and/or digital circuitry. In another example, the circuitry may be a combination of hardware circuitry and software, such as a combination of analog and/or digital hardware circuitry(s) and software or firmware, and/or any portion of hardware processor(s) with software (including digital signal processor (s)), software, and at least one memory that work together to cause the apparatus to perform various processes or functions. In yet another example, the circuitry may be hardware circuit(s) and/or processor(s), such as microprocessor(s) or a portion of microprocessor(s), including software, such as firmware for operation. Software in the circuitry may not be present when the hardware operation does not require software.

The above embodiments may be directed to computer-related techniques that provide significant improvements to the functionality of a network and/or the functionality of network entities within a network or the functionality of user equipment in communication with a network. For example, the above embodiments may help improve system or network performance while allowing finer frequency granularity and higher accuracy of channel state information feedback. Improving system or network performance may help reduce channel state information feedback overhead, thereby reducing network resource usage and/or resource usage at the user equipment.

The features, structures, or characteristics of some embodiments described throughout this specification may be combined in any suitable manner in one or more embodiments. For example, throughout the specification, use of the phrases "certain embodiments," "some embodiments," "other embodiments," or other similar language refers to the fact that: the particular features, structures, or characteristics described in connection with the embodiments may be included in at least one example embodiment of the invention. Thus, appearances of the phrases "in certain embodiments," "in some embodiments," "in other embodiments," or other similar language throughout this specification do not necessarily refer to the same group of embodiments, and the described features, structures, or characteristics may be combined in any suitable manner in one or more embodiments.

Those of ordinary skill in the art will readily appreciate that the exemplary embodiments of the invention, as described above, may be practiced with steps in a different order and/or with hardware elements in configurations that are different from those disclosed. Thus, while examples of the invention have been described based upon these preferred embodiments, it will be apparent to those skilled in the art that certain modifications, variations, and alternative constructions will be apparent, without departing from the spirit and scope of the invention. Although the above embodiments refer to 5G NR, the above embodiments may also be applied to any other current or future 3GPP technology, such as LTE, LTE-advanced (LTE-advanced), IoT technology, fourth generation (4G) technology, or any non-3 GPP technology.

Part of the vocabulary

3GPP third generation partnership project

CIR channel impulse response

CQI channel quality indication

CS compression sensing

CSI channel state information

DFT discrete Fourier transform

LTE Long term evolution

MIMO multiple input multiple output

MU-MIMO multiuser MIMO

NR new radio

OMP orthogonal matching pursuit

PUSCH physical uplink shared channel

RRC radio resource control

SB sub-band

SE spectral efficiency

ULA homogeneous linear array

WB broadband

Claims

1. An apparatus, comprising:

at least one processor; and

at least one memory and computer program code, wherein the at least one memory and the computer program code are configured, with the at least one processor, to cause the apparatus at least to:

determining a set of supported channels based on at least one of a first condition or a second condition, wherein the first condition includes the selected number of channel supports being greater than or equal to the configured number of channel supports, and wherein the second condition includes a variance of a residual matrix being less than or equal to a threshold variance; and

after determining that at least one of the first condition or the second condition has been met, sending a channel state information report including a set of channel support indices to a network entity based on the set of channels supported.

2. The apparatus of claim 1, wherein the set of channel support indices is common to one or more pairs of transmit and receive antenna ports.

3. The apparatus according to claim 1 or 2, wherein the selected channel support number is greater than or equal to the configured channel support number and at the same time the variance of the residual matrix is less than or equal to the threshold variance.

4. The apparatus according to any of claims 1 to 3, wherein the threshold variance depends on a variance of a time domain channel matrix and a threshold factor.

5. The apparatus of any of claims 1 to 4, wherein the at least one memory and the computer program code are configured to, with the at least one processor, cause the apparatus at least to:

the strongest coefficients of the compressed time domain channel matrix are determined.

6. The apparatus of claim 5, wherein the at least one memory and the computer program code are configured, with the at least one processor, to cause the apparatus at least to:

quantizing an index of the strongest coefficient of the compressed time-domain channel matrix, wherein the quantized index is included in the sent channel state information report.

7. The apparatus of claim 5 or 6, wherein the at least one memory and the computer program code are configured to, with the at least one processor, cause the apparatus at least to:

quantizing an amplitude and a phase of at least one of the strongest coefficient or other coefficients of the compressed time-domain channel matrix, wherein the quantized amplitude and phase are included in the transmitted channel state information.

8. The device of claim 7, wherein the magnitude of the strongest coefficient is quantized based on a ratio of the magnitude of the device to a reference signal received power.

9. The apparatus of any of claims 1 to 8, wherein the at least one memory and the computer program code are configured to, with the at least one processor, cause the apparatus at least to:

receiving a signal comprising one or more higher layer parameters from the network entity, wherein the one or more higher layer parameters comprise at least one of: the number of channel supports configured, the threshold factor, a discrete fourier transform matrix configuration, the set of indices quantized, or quantized bits of the amplitude and phase of the strongest or other coefficient.

10. The apparatus of claim 9, wherein the signal is a radio resource control signal.

11. The apparatus according to claim 9 or 10, wherein the one or more higher layer parameters are statically or semi-statically configured.

12. An apparatus, comprising:

at least one processor; and

receiving a channel state information report including a set of channel support indices from a user equipment based on a set of supported channels after at least one of a first condition or a second condition is satisfied, wherein the first condition includes a selected number of channel supports being greater than or equal to a configured number of channel supports, and wherein the second condition includes a variance of a residual matrix being less than or equal to a threshold variance; and

constructing a channel state matrix based on the set of channel support indices included in the channel state information report.

13. The apparatus of claim 12, wherein the set of channel support indices is common to one or more pairs of transmit and receive antenna ports.

14. The apparatus according to claim 12 or 13, wherein the at least one memory and the computer program code are configured to, with the at least one processor, cause the apparatus at least to:

receiving a quantized index of a strongest coefficient of a compressed time-domain channel matrix in the channel state information report, wherein the quantized index is used to construct the channel state matrix.

15. The apparatus of any of claims 12 to 14, wherein the at least one memory and the computer program code are configured, with the at least one processor, to cause the apparatus at least to:

receiving a quantized amplitude and phase of at least one of a strongest coefficient of the compressed time-domain channel matrix or other coefficients in the channel state information report, wherein the quantized amplitude and phase are used to construct the channel state matrix.

16. The apparatus of any of claims 12 to 15, wherein the at least one memory and the computer program code are configured, with the at least one processor, to cause the apparatus at least to:

transmitting a signal comprising one or more higher layer parameters to the user equipment, wherein the one or more higher layer parameters comprise at least one of: the number of channel supports configured, a threshold factor, a discrete fourier transform matrix configuration, the set of indices quantized, or quantized bits of the amplitude and phase of the strongest or other coefficient.

17. The apparatus of claim 16, wherein the signal is a radio resource control signal.

18. The apparatus according to claim 16 or 17, wherein the one or more higher layer parameters are statically or semi-statically configured.

19. An apparatus, comprising:

means for determining a set of supported channels based on at least one of a first condition or a second condition, wherein the first condition comprises the selected number of channel supports being greater than or equal to a configured number of channel supports, and wherein the second condition comprises a variance of a residual matrix being less than or equal to a threshold variance;

the components used for: after determining that at least one of the first or second conditions has been met, sending a channel state information report including a set of channel support indices to a network entity based on the set of channels supported.

20. An apparatus, comprising:

the components used for: receiving a channel state information report including a set of channel support indices from a user equipment based on a set of supported channels after at least one of a first condition or a second condition is satisfied, wherein the first condition includes a selected number of channel supports being greater than or equal to a configured number of channel supports, and wherein the second condition includes a variance of a residual matrix being less than or equal to a threshold variance; and

means for constructing a channel state matrix based on the set of channel support indices included in the channel state information report.

21. A method, comprising:

determining, at a user equipment, a set of supported channels based on at least one of a first condition or a second condition, wherein the first condition comprises the selected number of channel supports being greater than or equal to a configured number of channel supports, and wherein the second condition comprises a variance of a residual matrix being less than or equal to a threshold variance; and

after determining that at least one of the first condition or the second condition has been met, sending a channel state information report including a set of channel support indices from the user equipment to a network entity based on the set of channels supported.

22. The method of claim 21, wherein the set of channel support indices is common to one or more pairs of transmit and receive antenna ports.

23. The method of claim 21 or 22, wherein the selected channel support number is greater than or equal to the configured channel support number and at the same time the variance of the residual matrix is less than or equal to the threshold variance.

24. The method according to any of claims 21 to 23, wherein the threshold variance depends on a variance of a time domain channel matrix and a threshold factor.

25. The method of any of claims 21 to 24, further comprising:

26. The method of claim 25, further comprising:

27. The method of claim 25 or 26, further comprising:

28. The method of claim 27, wherein the amplitude of the strongest coefficient is quantized based on a ratio of the amplitude of the user equipment to a reference signal received power.

29. The method of any of claims 21 to 28, further comprising:

receiving, at a user equipment, a signal comprising one or more higher layer parameters from the network entity, wherein the one or more higher layer parameters comprise at least one of: the number of channel supports configured, the threshold factor, a discrete fourier transform matrix configuration, the set of indices quantized, or quantized bits of the amplitude and phase of the strongest or other coefficient.

30. The method of claim 29, wherein the signal is a radio resource control signal.

31. The method according to claim 29 or 30, wherein the one or more higher layer parameters are statically or semi-statically configured.

32. A method, comprising:

receiving, at a network entity, a channel state information report comprising a set of channel support indices based on a set of supported channels after at least one of a first condition or a second condition is satisfied, wherein the first condition comprises a selected number of channel supports being greater than or equal to a configured number of channel supports, and wherein the second condition comprises a variance of a residual matrix being less than or equal to a threshold variance; and

33. The method of claim 32, wherein the set of channel support indices is common to one or more pairs of transmit and receive antenna ports.

34. The method of claim 32 or 33, further comprising:

35. The method of any of claims 32 to 34, further comprising:

36. The method of any of claims 32 to 35, further comprising:

37. The method of claim 36, wherein the signal is a radio resource control signal.

38. The method according to claim 36 or 37, wherein the one or more higher layer parameters are statically or semi-statically configured.

39. A computer program product encoding instructions for performing a process, the process comprising:

40. A computer program product encoding instructions for performing a process, the process comprising: