CN117914367A - Wireless communication apparatus and method employing channel state information compression - Google Patents
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Abstract
Disclosed are a wireless communication apparatus and a method employing channel state information compression, in particular, a method of operating a wireless communication apparatus, the method comprising: receiving a channel state information reference signal (CSI-RS) from a base station, generating channel information by estimating a channel between a wireless communication device and the base station based on the CSI-RS, and reporting the channel information to the base station, wherein generating the channel information comprises: generating first compressed data by compressing channel characteristic information of a sub-band receiving the CSI-RS in a spatial domain, generating second compressed data by compressing the first compressed data in a frequency domain using a first Discrete Fourier Transform (DFT) function, wherein the first DFT function has a size corresponding to the number of sub-bands receiving the CSI-RS in a bandwidth part (BWP) for communication with a base station, and generating the channel information based on the second compressed data.
Description
The present application is based on and claims priority of korean patent application No. 10-2022-0133617 filed by the korean intellectual property office at 10 month 17 of 2022 and korean patent application No. 10-2023-0018042 filed at 10 month 2 of 2023, the disclosures of which are incorporated herein by reference in their entireties.
Technical Field
The present disclosure relates to an apparatus for compressing channel state information in a wireless communication system and a method of operating the same.
Background
Wireless communication devices conforming to the recent third generation partnership project (3 GPP) standards (e.g., rel.16) may perform communication with a base station using an enhanced type II (ettypelii) codebook to reduce the overhead of Channel State Information (CSI) feedback. By using eTypeII codebook, overhead reduction can be achieved by feeding back channel information using correlation characteristics between space and frequency of CSI. For this purpose, the following process may be followed: 1) The base station transmits channel state information-resource signals (CSI-RS) to the wireless communication device using antenna ports and time/frequency Resource Elements (REs) defined in the standard. 2) The wireless communication device estimates a multiple-input multiple-output (MIMO) channel between the base station and the wireless communication device from the received CSI-RS signal and then generates CSI to be reported to the base station. In the CSI generation process of step 2), the wireless communication apparatus determines precoding (or beamforming) at the base station and transmits corresponding channel information (e.g., precoding Matrix Indicator (PMI)) in a compressed form according to eTypeII codebook in consideration of spatial/frequency domain characteristics of the precoding at the base station.
The channel information compression process advantageously enables the wireless communication device to transmit channel information using fewer wireless communication resources (e.g., time/frequency REs). The precoded spatial domain characteristics of the base station select a base with dominant values among the bases of the spatial domain in which the values corresponding to the antenna ports are re-expressed in the oversampled Discrete Fourier Transform (DFT) space. The frequency domain characteristics of precoding at the base station select a dominant basis among the basis of the frequency domain in which a value corresponding to the frequency of the channel information is re-expressed in the DFT space. Only precoding values for precoding at the base station are reported to the base station, wherein the precoding values are re-expressed in a small-Dimension (DFT) space determined by a compression process of channel information for selecting a space/frequency dimension as a base of the selected space/frequency domain.
Accordingly, in the process of compressing channel information, the compression of the space/frequency domain is performed in consideration of the space/frequency domain characteristics of the precoding at the base station, and a wireless communication apparatus that minimizes the loss of channel information in the compression process is desired.
Disclosure of Invention
Embodiments of the inventive concept provide a terminal apparatus to reduce overhead of Channel State Information (CSI) reporting and perform efficient CSI feedback through compression of channel information. When channel state information-reference signals (CSI-RS) are transmitted in at least some subbands of an entire bandwidth portion (BWP), compression may be based on information about the subbands in which the CSI-RS is received in the wireless communication system.
According to an aspect of the inventive concept, there is provided a method of operating a wireless communication device, the method comprising: receiving a channel state information reference signal (CSI-RS) from a base station, generating channel information by estimating a channel between a wireless communication device and the base station based on the CSI-RS, and reporting the channel information to the base station, wherein generating the channel information comprises: generating first compressed data by compressing channel characteristic information of a subband receiving the CSI-RS in a spatial domain, generating second compressed data by compressing the first compressed data in a frequency domain using a first Discrete Fourier Transform (DFT) function having a size corresponding to the number of subbands receiving the CSI-RS in a bandwidth part BWP for communication with a base station, and generating the channel information based on the second compressed data.
According to another aspect of the inventive concept, there is provided a method of operating a wireless communication device, the method comprising: receiving a CSI-RS from a base station, generating channel information by estimating a channel between a wireless communication device and the base station based on the CSI-RS, and reporting the channel information to the base station, wherein generating the channel information comprises: generating first compressed data by compressing channel characteristic information of a subband receiving the CSI-RS in a spatial domain, generating second compressed data by compressing the first compressed data in a frequency domain using a first partial DFT function, and generating the channel information based on the second compressed data, wherein the first partial DFT function is composed of a column domain corresponding to a subband constituting a BWP for communication with a base station and a row domain corresponding to the subband receiving the CSI-RS.
According to another aspect of the inventive concept, there is provided a method of operating a wireless communication device, the method comprising: receiving a CSI-RS from a base station, generating channel information by estimating a channel between a wireless communication device and the base station based on the CSI-RS, and reporting the channel information to the base station, wherein generating the channel information comprises: generating first compressed data by compressing channel characteristic information of a sub-band receiving the CSI-RS in a spatial domain, performing preprocessing on sub-bands not receiving the CSI-RS among sub-bands of BWP for communication with the base station according to a preset method, generating second compressed data by compressing the preprocessed first compressed data in a frequency domain using a DFT function having a size corresponding to the number of sub-bands constituting the BWP, and generating the channel information based on the second compressed data.
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The embodiments will be more clearly understood from the following detailed description taken in conjunction with the accompanying drawings in which:
fig. 1 illustrates an example of a wireless communication system according to an example embodiment;
fig. 2 is a block diagram illustrating a wireless communication device according to an example embodiment;
Fig. 3 is a block diagram illustrating an example of a particular implementation of the first Radio Frequency Integrated Circuit (RFIC) and first antenna module of fig. 2;
fig. 4 is a block diagram of a channel information compression circuit according to an example embodiment;
Fig. 5 is a flowchart illustrating a method of operation of a wireless communication device according to an example embodiment;
fig. 6A and 6B are diagrams for explaining a Frequency Domain (FD) compression operation by a first sub-transform block according to an example embodiment;
fig. 7 is a flowchart illustrating a method of operation of a wireless communication device according to an example embodiment;
fig. 8A, 8B, 8C, 8D, and 8E are diagrams for explaining an FD compression operation by a second sub-transform block according to an example embodiment;
Fig. 9 is a flowchart illustrating a method of operation of a wireless communication device according to an example embodiment;
fig. 10A, 10B, 10C, and 10D are diagrams for explaining an FD compression operation by a third sub-transform block according to an example embodiment;
fig. 11 is a flowchart illustrating a method of operation of a wireless communication device according to an example embodiment;
Fig. 12A, 12B, 12C, 12D, 12E, 12F, and 12G are diagrams for explaining an FD compression operation by a fourth sub-transform block according to an example embodiment; and
Fig. 13 is a block diagram illustrating an electronic device according to an example embodiment.
Detailed Description
Hereinafter, embodiments will be described in detail with reference to the accompanying drawings.
For ease of description, the description uses in part terms and names defined in the third generation partnership project long term evolution (3 GPP LTE) standard or the New Radio (NR) standard. However, the inventive concept is not limited by the above terms and names, and may be equally applied to systems conforming to other standards.
In this context, the word "index" may be understood to mean an "index value" (rather than a list of values) as is customary in modern wireless communication standards.
In this document, the word "FD column index" may be understood to mean "FD base (e.g., FD base index) or FD column vector".
Examples of entities that communicate with and allocate communication network resources to wireless communication devices according to embodiments include cells, base Stations (BSs), nodebs (NB), enodbs (enbs), next Generation Radio Access Networks (NGRAN), radio access units, base station controllers, nodes on the network, and gnodebs (gnbs).
A wireless communication apparatus is an entity that communicates with a base station or other wireless communication apparatus, examples of which include a node, a User Equipment (UE), a next generation UE (NG UE), a Mobile Station (MS), a Mobile Equipment (ME), an apparatus, and a terminal.
Other examples of wireless communication devices may include at least one of: smart phones, tablet Personal Computers (PCs), mobile phones, video phones, e-book readers, desktop PCs, laptop PCs, netbook computers, personal Digital Assistants (PDAs), portable Multimedia Players (PMPs), MP3 players, medical devices, cameras, and wearable devices. Further, the wireless communication device may include at least one of: televisions, digital Video Disc (DVD) players, audio devices, refrigerators, air conditioners, vacuum cleaners, ovens, microwave ovens, washing machines, air cleaners, set top boxes, home automation control panels, security control panels, media boxes (e.g., samsung HomeSync TM、Apple TVTM and Google TV TM), gaming machines (e.g., xbox TM and PlayStation TM), electronic dictionaries, electronic keys, cameras, and electronic photo frames. Other examples of wireless communication devices may include at least one of: various medical devices (e.g., various portable medical measurement devices such as blood glucose monitors, heart rate monitors, blood pressure monitors or body temperature monitors, magnetic Resonance Angiography (MRA), magnetic Resonance Imaging (MRI), computed Tomography (CT), imaging devices or ultrasound, etc.), navigation devices, global Navigation Satellite Systems (GNSS), event Data Recorders (EDR), flight Data Recorders (FDR), automotive infotainment devices, marine electronics (e.g., marine navigation systems, gyrocompass, etc.), avionics, security devices, vehicle host units, industrial or home robots, unmanned aerial vehicles, automated Teller Machines (ATM) at financial institutions, point of sale (POS) at stores, and internet of things (IoT) devices (e.g., light bulbs, various sensors, sprinkler devices, fire alarms, thermostats, street lamps, toasters, sports equipment, hot water boxes, heaters, boilers, etc.). Other examples may include various types of multimedia systems capable of performing communication functions.
Hereinafter, embodiments will be described in detail with reference to the accompanying drawings.
Fig. 1 is a block diagram illustrating a wireless communication system according to an embodiment.
Referring to fig. 1, a wireless communication system 10 may include a base station 200 and a wireless communication device 100. The wireless communication system 10 is shown to include only one base station 200 and one wireless communication apparatus 100, but this is merely an example for simplicity of illustration; the wireless communication system 10 may be implemented to include various numbers of base stations and wireless communication devices.
The base station 200 may be connected to the wireless communication device 100 through a radio channel to provide various communication services. The base station 200 may serve all user traffic through a shared channel and perform scheduling by collecting status information such as a buffer status, an available transmission power status, and a channel status of the wireless communication device 100. The wireless communication system 10 may support beamforming techniques using Orthogonal Frequency Division Multiplexing (OFDM) as a radio access technology. In addition, the wireless communication system 10 may support an Adaptive Modulation and Coding (AMC) method for determining a modulation scheme and a channel coding rate according to the channel condition of the wireless communication apparatus 100.
The wireless communication system 10 may transmit and receive signals using a wide frequency band existing in a frequency band of 6GHz or higher. For example, wireless communication system 10 may achieve high data transmission rates by using millimeter wave frequency bands, such as the 28GHz band or the 60GHz band. Now, since the millimeter wave band has a signal attenuation according to a relatively large distance, the wireless communication system 10 can support transmission and reception based on directional beams generated using a plurality of antennas to ensure coverage. The wireless communication system 10 may be a system supporting multiple-input multiple-output (MIMO), and thus the base station 200 and the wireless communication apparatus 100 may support beamforming techniques. Beamforming techniques may be classified as digital beamforming, analog beamforming, and hybrid beamforming. Hereinafter, the spirit of the present technology will be described in a wireless communication system based on an embodiment supporting a hybrid beamforming technique, but it will be fully understood that the present technology can be applied to other beamforming techniques.
As shown in fig. 1, the base station 200 may transmit channel state information-reference signals (CSI-RS) to the wireless communication device 100. The wireless communication device 100 may estimate the downlink channel using CSI-RS.
The wireless communication device 100 may utilize CSI compression techniques (e.g., spatial/frequency domain compression techniques) to accurately transmit channel state information to a base station using reduced uplink resources. As an example, the wireless communication apparatus 100 may generate first compressed data based on a subband pass receiving the CSI-RS and generate second compressed data by performing frequency domain compression on the first compressed data using various Discrete Fourier Transform (DFT) functions. The wireless communication device 100 may transmit channel information (e.g., CSI report) generated based on the second compressed data to the base station 200.
The inventive concept relates to a method for improving/maximizing compression performance of channel information by reporting the channel information through a frequency domain compression technique based on various DFT functions, as will be described in detail below.
Fig. 2 is a block diagram illustrating a wireless communication device 100 according to an example embodiment. The component may be part of a modem chip of the wireless communication device 100.
The wireless communication device 100 may include a baseband processor 110, a first RF integrated circuit (RFIC) 120, first to i-th antenna modules 130_1 to 130_i (i=two or more), a second RFIC 140, a plurality of antennas 150, and a memory 160.
The baseband processor 110 may control the overall operation of the wireless communication device 100. For example, baseband processor 110 may include channel quality measurement circuitry 112, switch control circuitry 114, and Channel State Information (CSI) compression circuitry 116.
Channel quality measurement circuitry 112, switch control circuitry 114, and CSI compression circuitry 116 may be implemented as hardware or through the use of software. The operation of channel quality measurement circuitry 112, switch control circuitry 114, and CSI compression circuitry 116, which will be described below, may be understood as the operation of baseband processor 110.
When communicating with the base station 200 or other devices, the channel quality measurement circuit 112 may measure the channel quality of the first to i-th antenna modules 130_1 to 130_i in order to identify whether the channel of the primary component carrier is degraded among the plurality of component carriers.
The channel quality measurement circuit 112 may measure a condition of a channel of a signal received through each of the first to i-th antenna modules 130_1 to 130_i and generate an indicator indicating a channel condition for each of the plurality of component carriers corresponding to the first to i-th antenna modules 130_1 to 130_i based on the measured channel condition.
For example, the channel quality measurement circuitry 112 may measure at least one of: rank Indicator (RI), channel Quality Indicator (CQI), reference Signal Received Power (RSRP), reference Signal Received Quality (RSRQ), signal to interference plus noise ratio (SINR), received Signal Strength Indicator (RSSI), reference signal related correlation, and variable gain index of the received signal.
The switch control circuit 114 may control the connection between the first to i-th antenna modules 130_1 to 130_i and the first RFIC 120 based on the received layer allocation information to perform communication with the base station 200 device or other devices. The first RFIC 120 may include first to kth RF chains 121_1 to 121—k corresponding to RF resources. Each of the first to i-th antenna modules 130_1 to 130_i (antenna-related circuit groups) may include first to m-th antenna arrays 130_11 to 130_1. Each of the first to mth antenna arrays 130_11 to 130_1 may include first to nth RF front ends 131_11 to 131_1n and first to nth antennas 132_11 to 132_1n. The switch control circuit 114 may control the connection between the first to kth RF chains 121_1 to 121—k and the first to mth antenna arrays 130_11 to 130_1 of the first to ith antenna modules 130_1 to 130_i according to the layer allocation information received from the base station 200 device.
The switch control circuit 114 may control the connection between the selected antenna module and the first RFIC 120 based on layer allocation information received from the base station 200 device. For example, the switch control circuit 114 may disconnect the selected antenna module from the first RFIC 120 based on layer allocation information received from the base station 200 apparatus and perform an antenna module switching operation by controlling the connection between another antenna module and the first RFIC 120.
For example, the first RFIC 120 may support communication in the millimeter wave band and the second RFIC 140 may support communication in a band below the millimeter wave band. The second RFIC 140 may be selectively connected to a plurality of antennas 150.
CSI compression circuitry 116 may perform spatial domain compression and frequency domain compression based on reference signals (e.g., CSI-RS) received from base station 200 and generate channel information for channel information reporting (e.g., cell Specific Reference (CSR) -Resource Signal (RS) reporting). The generated channel information may be stored in an Uplink Control Information (UCI) bit sequence and reported to the base station 200.
The memory 160 may store indicators of the first to i-th antenna modules 130_1 to 130_i. The memory 160 may store information required for connection control between the first RFIC 120 and the first to i-th antenna modules 130_1 to 130_i. In some embodiments, the channel quality measurement circuit 112 and the switch control circuit 114 may be implemented as software and stored in the memory 160 in code form. Switch history information may also be stored in memory 160.
For example, memory 160 may be implemented with volatile memory, such as Static Random Access Memory (SRAM). In some embodiments, memory 160 may be implemented as volatile memory, such as Dynamic Random Access Memory (DRAM), or non-volatile memory, such as ROM, flash memory, resistive random access memory (ReRAM), or Magnetic Random Access Memory (MRAM).
Fig. 3 is a block diagram illustrating an example of a specific implementation of the first RFIC and first antenna module of fig. 2.
In detail, in fig. 3, as the first RFIC and the first antenna module of the wireless communication apparatus 100, the wireless communication apparatus 100 of fig. 3 reports (or transmits) channel information compressed in the spatial/frequency domain by the CSI compression circuit 116 to the base station through the first RFIC 120a and the first antenna module 130_1a.
Referring to fig. 3, the first RFIC 120a of the wireless communication device 100 of fig. 3 may include first to kth RF chains 121_1a to 121_ka and a switch interface 122a. The embodiment example of the first antenna module 130_1a described in fig. 3 may also be applied to the second to i-th antenna modules 130_2 to 130_i of fig. 2. For example, in the wireless communication system, at an initial stage of access between the base station 200 and the wireless communication apparatus 100, connections between the first to kth RF chains 121_1a to 121_ka and the first antenna module 130_1a may be controlled based on layer allocation information set by the base station 200.
For example, when the channel state of the primary component carrier is deteriorated in the wireless communication system, the switching interface 122a may control the connection between the first to kth RF chains 121_1a to 121_ka and the first antenna module 130_1a based on the changed layer allocation information received from the base station 200.
Each of the first to kth RF chains 121_1a to 121_ka may include an analog-to-digital converter ADC, a mixer MX, and a variable gain amplifier VGA. The variable gain amplifier VGA may amplify the received signal based on the variable gain, the mixer MX may down-convert the amplified signal based on the frequency signal LO, and the analog-to-digital converter ADC may convert the converted signal into a digital signal. The digital signal output from the analog-to-digital converter ADC may be provided to the baseband processor 110 of fig. 2.
The analog-to-digital converter ADC, the mixer MX and the variable gain amplifier VGA form a path for a signal received by the wireless communication device 100, and the first to kth RF chains 121_1a to 121_ka of fig. 3 may further include components forming a path for a signal transmitted by the wireless communication device 100. The switching interface 122a may connect the first to kth RF chains 121_1a to 121_ka with the first antenna module 130_1a in response to the switching control signal.
The first antenna module 130_1a may include first to mth antenna arrays 130_11a to 130_1ma and first to mth combiners 133_1a to 133_ma. An embodiment example of the first antenna array 130_11a may be applied to the second antenna array 133_12a to the mth antenna array 130_1ma. Each of the first to mth antenna arrays 130_11a to 130_1ma may include first to nth RF front ends 131_1a to 131_1na and first to mth antennas 132_1a to 132_ma connected thereto. Each of the first to nth RF front ends 131_1a to 131_1na may include a phase shifter PS and a low noise amplifier LNA. By the phase adjustment of the plurality of phase shifters PS included in the first antenna module 130_1a, a plurality of reception beam direction patterns may be formed in the first antenna module 130_1a. The first to mth combiners 133_1a to 133_ma may combine the signals received from the connected first to mth antenna arrays 130_11a to 130_1ma and output the summed signals to the first RFIC 120a.
The implementation of the first RFIC 120a and the first antenna module 130_1a of fig. 3 is merely an example embodiment, but is not limited thereto, and various implementations suitable for communication in the millimeter wave band will be applicable.
Fig. 4 is a block diagram of a channel state information compression circuit according to an example embodiment. The block diagram shows the spatial domain compression process and the frequency domain compression process of the baseband processor 110 (specifically, the CSI compression circuit 116 of fig. 2).
As shown in fig. 4, CSI compression circuitry 116 may include a Spatial Domain (SD) compression block 410, a Frequency Domain (FD) compression block 420 (including a non-zero coefficient (NZC) selection and quantization block 427), and an Uplink Channel Information (UCI) bit sequence generation block 430.
Based on the received CSI-RS, SD compression block 410 may perform spatial domain compression by using a spatial codebook according to the spatial domain characteristics of the subbands of the received CSI-RS. For example, the SD compression block 410 may re-express a value corresponding to an antenna port of a base station in an oversampled Discrete Fourier Transform (DFT) space (interchangeably, "oversampled DFT space"), and then select an SD base (base) having a dominant value among candidate bases (e.g., column vectors).
FD compression block 420 may include DFT transform block 421, FD base selection block 426, NZC selection and quantization block 427, and bypass path 428. (note that when the number of subbands constituting BWPNumber of subbands with received CSI-RS/>Where the ratio of (a) is an integer, the bypass path 428 may be used).
The DFT transform block 421 may include a first sub-transform block 421, a second sub-transform block 422, a third sub-transform block 423, and a fourth sub-transform block 424. When the CSI-RS is received in some sub-bands of the entire BWP for communication between the base station and the wireless communication device, the DFT transform block 421 according to the embodiment may perform frequency domain compression using any one of the first sub-transform block 421, the second sub-transform block 422, the third sub-transform block 423, or the fourth sub-transform block 424. When the CSI-RS is received over the entire BWP, although not shown in fig. 4, frequency domain compression may be performed using a DFT function (e.g., a DFT function defined in 3gpp rel.16 or rel.17) corresponding to the entire BWP size.
In one embodiment, a matrix corresponding to an nth sub-band of the SD compressed first compressed data is defined as V n∈CL×Rank, and here, L may refer to a dimension reduced by SD compression, and Rank may refer to a total number of layers for MIMO communication between a base station and a terminal.
In one embodiment, the DFT transformed input matrixMay be a matrix generated by extracting the first layer of each subband of the received CSI-RS from the SD compressed first compressed dataForm of the invention. The/> can be expressed based on equation 1Where L may refer to the dimension reduced by SD compression.
[ Equation 1]
In one embodiment, the first sub-transform block 421 may generate the second compressed data by compressing the first compressed data in the frequency domain using a DFT function having a size corresponding to the number of subbands receiving the CSI-RS. A detailed description of this will be described later with reference to fig. 5 to 6B. The second sub-transform block 422 may generate second compressed data by compressing the first compressed data in the frequency domain using a DFT function that is oversampled according to the number of subbands receiving the CSI-RS. A detailed description of this will be described later with reference to fig. 7 to 8E. The third sub-transform block 423 may generate the second compressed data by compressing the first compressed data in the frequency domain using a partial DFT function in a form determined based on the number of subbands constituting the BWP and the number of subbands receiving the CSI-RS. A detailed description of this will be described later with reference to fig. 9 to 10D. The fourth sub-transform block 424 may perform preprocessing on subbands not receiving the CSI-RS among the subbands constituting the BWP and generate second compressed data by compressing the preprocessed first compressed data in the frequency domain using a DFT function. This will be described in detail later in fig. 11 to 12G.
The FD base selection block 426 may receive the second compressed data from the DFT transformation block 421 and select a dominant base of the second compressed data as an FD base. Here, the FD base may refer to an index of a column having a dominant value in the first compressed data re-expressed in the DFT space. For example, the FD base selection block 426 may calculate an average value of squares of components of each column of the second compressed data on which FD compression is performed, sort the average values according to the size, and then select and output a preset number of FD bases (for example, an order in which the magnitudes of the average values of squares of each column component are large).
The NZC selecting and quantizing block 427 may calculate absolute values of components included in the second compressed data in the form of "SD base×fd base", sort the absolute values according to the size, and then select a preset number of NZCs (e.g., select an order having a large absolute value). NZC selection and quantization block 427 may select NZC based on a matrix composed of column vectors corresponding to the first compressed data and FD column index (e.g., FD base (or FD base index)). Specifically, NZC is selected based on the absolute values of elements included in a matrix composed of column vectors corresponding to the first compressed data and FD column indexes (e.g., FD base (or FD base index)). The NZC selection and quantization block 427 may quantize the selected FD base and NZC into a form that may be represented in the UCI bit sequence.
However, UCI bit sequence generation block 430 may receive the quantized FD base and NZC from NZC selection and quantization block 427 and generate UCI bit sequences for CSI reporting to the base station.
According to the embodiments, when CSI-RS of BWP is transmitted from a base station through some subbands, a wireless communication apparatus in which compression performance of channel information is maximized by effectively performing frequency domain compression within a range where channel information of a subband transmitting the CSI-RS is not damaged may be provided.
By the processing of compressing channel information in the frequency domain according to the technical ideas of the present inventive concept, a wireless communication apparatus capable of preventing deformation and contamination (or distortion) of CSI report contents due to interference between channels can be provided.
Fig. 5 is a flowchart illustrating a method of operating a wireless communication device according to an example embodiment.
In detail, fig. 5 is a diagram for explaining an operation of performing CSI-RS dimensional FD compression on channel characteristic information by the baseband processor 110 (e.g., the first sub-transform block 422 of fig. 4) when CSI-RS is received in some subbands of the entire BWP in the baseband processor 110 of the wireless communication device 100 of fig. 2.
Herein, the "CSI-RS dimension" may refer to the number of some subbands (less than all subbands of BWP) of the BWP-based subbands that receive CSI-RSThe converted DFT space, and "BWP dimension" may refer to/>, based on the number of subbands included in BWPThe converted DFT space.
Referring to fig. 5, the operation of generating channel information by compressing channel characteristic information in the spatial and frequency domains may include operation S10, operation S20, operation S30, operation S40, operation S50, operation S60, and operation S70.
In operation S10, the baseband processor 110 may receive the CSI-RS from the base station. For example, the base station transmits CSI-RS to the terminal using predefined antenna ports and radio communication resources (e.g., time/frequency Resource Elements (REs)).
In operation S20, the baseband processor 110 may determine (or identify) whether the CSI-RS is received through less than all of the subbands of BWP or whether one or more subbands of interest are designated by the base station (when the CSI-RS is transmitted in all of the subbands of BWP). Since CSI-RS may be freely allocated within BWP by the base station, CSI-RS may be transmitted in all subbands of BWP or only in some subbands in BWP. Herein, when the CSI-RS is said to be received in "some subbands" within the BWP, this may cover 1) a case where the CSI-RS is received in less than all subbands within the BWP, and 2) a case where the CSI-RS is transmitted by the base station on the entire BWP, but the base station specifies at least one subband of interest through CSI reporting band information (e.g., bit sequence), and requests CSI reporting only for the corresponding at least one subband.
When the CSI-RS is received through some subbands of BWP, the baseband processor 110 may perform operation S30. When the CSI-RS is received through all the subbands of the BWP, the baseband processor 110 may generate channel information by estimating a channel based on the CSI-RS in operation S40.
In operation S30, the baseband processor 110 may compress channel characteristic information of a sub-band receiving the CSI-RS in a spatial domain (hereinafter, referred to as SD compression) to generate first compressed data. For example, the baseband processor 110 re-expresses spatial domain characteristics (e.g., values corresponding to antenna ports) of subbands receiving the CSI-RS as an oversampled Discrete Fourier Transform (DFT) space, and then selects a dominant SD basis among the SD bases. Wherein, the channel characteristic information of the subband receiving the CSI-RS may be understood to mean "spatial domain characteristics (e.g., dominant SD basis) of the subband receiving the CSI-RS". The baseband processor 110 may generate first compressed data composed of a selected SD base instead of a base constituting an existing BWP. That is, the first compressed data may be configured in the form of a matrix having a dimension reduced by the selected SD basis as compared to before compression.
In operation S50, the baseband processor 110 may generate second compressed data using a DFT function having a size corresponding to the number of subbands receiving the CSI-RS. That is, the baseband processor 110 may generate the second compressed data by compressing the first compressed data (hereinafter, referred to as FD compression) in the frequency domain using a DFT function. For example, the baseband processor 110 may select an FD base indicating an index of a column having a dominant value among second compressed data obtained by re-expressing the first compressed data in the DFT space. In addition, the baseband processor 110 may calculate absolute values of components included in second compressed data (e.g., matrix-form data) in the DFT conversion space, and select a preset number of NZCs according to the magnitude of the absolute values. The baseband processor 110 may quantize channel information including the selected FD base and NZC to display the channel information in a UCI bit sequence. A detailed description thereof will be described later with reference to fig. 6A and 6B.
In operation S60, the baseband processor 110 may generate channel information based on the second compressed data. For example, the baseband processor 110 may generate UCI bit sequences based on quantized channel information (e.g., information on the selected FD base and NZC).
In operation S70, the baseband processor 110 may report channel information to the base station. The base station may determine a precoder for downlink data transmission by receiving a report of spatial/frequency domain compressed channel information of the wireless communication device. Additionally, in an embodiment according to the inventive concept, the base station may perform CSI-RS configuration and CSI configuration again based on the channel information report of the wireless communication device. The base station may learn the information amount of the corresponding channel based on spatial/frequency domain compressed channel information reports of the wireless communication device. The information amount of the channel may be determined based on an energy distribution of the NZC corresponding to the reported FD base. For example, if the energy of the NZC is concentrated on a certain FD base, the base station may control the wireless communication device to increase the compression rate of channel information to minimize the amount of overhead generated by CSI reporting.
Therefore, according to the wireless communication system of the embodiment, by adjusting the size of the CSI-RS allocation region according to the amount of channel information by the base station, there is an effect of improving the spectrum efficiency by transmitting data only for specific wireless communication resources. In addition, the wireless communication apparatus according to the technical idea of the present inventive concept can prevent distortion and distortion of CSI report contents due to interference through compression processing in a Frequency Domain (FD).
Fig. 6A and 6B are diagrams for explaining an FD compression operation by the first sub-transform block according to an example embodiment.
In detail, fig. 6A and 6B show diagrams for explaining FD compression operations by the first sub-transform block 422 of fig. 4.
Fig. 6A illustrates a case in which the CSI-RS of the first case is received in some subbands within the BWP as in operation S20 of fig. 5, and fig. 6B illustrates a case in which CSI reporting band information (e.g., bit sequence) is requested from the base station for CSI reporting only for the subbands of interest as in the second case in operation S20 of fig. 5.
As described above, the "CSI-RS dimension" may refer to the number based on some subbands in BWP receiving CSI-RSThe converted DFT space, and the "BWP dimension" may refer to the number/>, based on the number of subbands included in BWPThe converted DFT space.
In fig. 6A and 6B, the baseband processor 110 generates second compressed data using a DFT function (e.g., a DFT function in a previously defined "CSI-RS dimension") set to correspond to the number of subbands receiving the CSI-RS for the size (e.g., K points) of the DFT transform.
Referring to fig. 6A, in the first case, a BWP 610 for communication between a base station and the wireless communication device 100 includes first to nth subbands SB 1 toFirst to nth subbands SB 1 to/>Including sub-band 620, which receives CSI-RS.
In one embodiment, in the first case, baseband processor 110 (e.g., CSI compression circuitry 116) uses a DFT function having a size corresponding to the number of subbands receiving CSI-RSCompressing the first compressed data (hereinafter referred to as FD compression) in the frequency domain (e.g., DFT function in CSI-RS dimension) to generate second compressed data/>(At this time, FD compression may be performed for each layer in the first compressed data). For example, second compressed data/>May be calculated based on equation 2.
[ Equation 2]
Here the number of the elements is the number,Is the DFT-transformed input matrix determined based on equation 1 in FIG. 4,/>Can refer to the size as/>/>Dot DFT matrix, and/>May refer to the number of subbands receiving CSI-RS.
Referring to fig. 6B, in the second case, the BWP 610 includes first to nth subbands SB 1 to SBFor example, the base station may indicate the sub-band 651 of interest as '1' (active) and transmit a bit sequence (e.g., CSI report band information) with the sub-band 652 of no interest indicated as '0' (inactive) to the wireless communication device 100.
In the second case, when there is an uninteresting subband among subbands receiving CSI-RS, baseband processor 110 (e.g., CSI compression circuit 116) may determine the DFT size for FD compression asIn this case, the baseband processor 110 may also generate second compressed data/>, based on equation 3 below(At this time, FD compression may be performed for each layer in the first compressed data).
[ Equation 3]
Here the number of the elements is the number,Is an input matrix for DFT transformation of the sub-band of interest and is determined based on equation 1 of fig. 4, and/>Can refer to being set to AND/>DFT functions of corresponding size (e.g., CSI-RS dimensional DFT functions).
After FD compression, baseband processor 110 may calculate and sort norms for each column of second compressed data to determine an index for (or select) columns with dominant values for the FD base.
Fig. 7 is a flowchart illustrating a method of operating a wireless communication device according to an example embodiment.
In detail, fig. 7 is a diagram for explaining an operation of performing FD compression by mapping to BWP-dimensional FD compression after CSI-RS-dimensional FD compression (e.g., application of oversampling DFT) is performed by baseband processor 110 (e.g., second sub-transform block 423 of fig. 4) and an operation of performing FD compression by mapping to BWP-dimensional FD compression when CSI-RS is received in some subbands of the entire BWP in baseband processor 110 of wireless communication device 100 of fig. 2.
Referring to fig. 7, the operation of performing FD compression by mapping to the (previously defined) BWP dimension after performing CSI-RS dimension FD compression may include operation S51, operation S53, and operation S55. Here reiterated, herein, the CSI-RS dimension may refer to the number based on some subbands in BWP receiving CSI-RSThe converted DFT space, and BWP dimension may refer to the number/>, based on the number of subbands included in BWPThe converted DFT space.
In operation S51, the baseband processor 110 may determine (or identify) the number of subbands constituting the BWPNumber of subbands with received CSI-RS/>Whether the ratio Z of (c) is an integer. Here, Z may refer to/>For example, when the number of subbands constituting BWP is '6' and the number of subbands through which CSI-RS is received is '2', Z is an integer '3'. For example, when the number of subbands constituting BWP is '7' and the number of subbands through which CSI-RS is received is '2', Z is '3.5' which is not an integer.
In operation S53, the baseband processor 110 may generate second compressed data of the CSI-RS dimension by using an oversampled DFT function (interchangeably referred to as an "oversampled DFT function") that it may generate. The oversampling factor may beFor example, baseband processor 110 may generate an oversampled DFT function (e.g., CSI-RS dimensional DFT function) by applying at least one of a rotation index or a position indication matrix of the CSI-RS. The baseband processor 110 may generate second compressed data by compressing the first compressed data in the frequency domain using an oversampled DFT function. A detailed description of this will be described later with reference to fig. 8A to 8E. /(I)
In operation S55, the baseband processor 110 may generate channel information by mapping the second compressed data of the CSI-RS dimension to the BWP dimension.
After applying the oversampling DFT, the baseband processor 110 may select the FD base and NZC based on the FD base and NZC selection methods described above in fig. 4.
Baseband processor 110 may map the FD group selected in the CSI-RS dimension to the FD group in the BWP dimension by multiplying the FD group selected in the CSI-RS dimension by a ratio Z, or baseband processor 110 may map the FD group selected in the CSI-RS dimension to the FD group in the BWP dimension by adding the rotation index to a value obtained by multiplying the FD group selected in the CSI-RS dimension by the ratio Z.
When the ratio of the number of subbands constituting the BWP to the number of subbands through which the CSI-RS is received is an integer, the operation in which the baseband processor 110 may generate channel information further includes: baseband processor 110 may select an FD base (e.g., FD column index) corresponding to a reception region of the CSI-RS based on the second compressed data; and mapping FD base (e.g., FD column index) to correspond to the BWP region. Baseband processor 110 may calculate a value by adding the rotation index to an FD base (e.g., FD column index) multiplied by a ratio of the number of subbands constituting BWP to the number of subbands through which CSI-RS is received, and map the value to an FD base (e.g., FD column index) corresponding to the BWP region. Wherein the word "FD column index" may be understood to mean "FD base (e.g., FD base index)".
When the ratio of the number of subbands constituting the BWP to the number of subbands through which the CSI-RS is received is an integer, the operation in which the baseband processor 110 may generate channel information further includes: the baseband processor 110 may select a non-zero coefficient (NZC) based on a matrix composed of column vectors corresponding to the first compressed data and FD base (e.g., FD column index); and mapping NZC to correspond to the BWP region. Wherein selecting NZC comprises: the baseband processor 110 may select NZC based on absolute values of elements included in a matrix composed of column vectors corresponding to the first compressed data and FD base (e.g., FD column index). Wherein the word "FD column index" may be understood to mean "FD base (e.g., FD base index)".
The baseband processor 110 may perform phase compensation on the NZCs selected in the CSI-RS dimension according to a preset method to map the NZCs selected in the CSI-RS dimension to the NZCs in the BWP dimension. A detailed description of this will be described later with reference to fig. 8A to 8E.
Fig. 7 has been described on the premise that FD compression in the CSI-RS dimension is performed based on the DFT function of fig. 5, but is not limited thereto. For example, the baseband processor 110 according to an embodiment may perform FD compression in the CSI-RS dimension using various types of DFT functions, and the result of the execution is mapped to FD compression in the BWP dimension. In addition, the FD compression operation of fig. 7 may be applied as an independent embodiment in which the wireless communication device 100 maps channel characteristic information to FD compression of a high dimension (e.g., BWP dimension) after FD compression of a low dimension (e.g., CSI-RS dimension).
Baseband processor 110 according to an embodiment may replace FD compression in the BWP dimension with FD compression in the CSI-RS dimension. This has the effect of reducing the amount of overhead generated in the FD compression process and reducing the power consumption. In addition, the wireless communication apparatus according to the technical concept of the present invention can prevent degradation and distortion of CSI report contents due to interference by compressing the processing of channel information in the frequency domain.
Fig. 8A to 8E are diagrams for explaining an FD compression operation by the second sub-transform block according to an example embodiment.
In detail, fig. 8A to 8E are diagrams for explaining FD compression operations (e.g., operations mapped to FD compression in BWP dimension after FD compression in CSI-RS dimension) of the second sub-transform block 423 of fig. 4.
As previously described, in this document, the CSI-RS dimension may refer to the number of some subbands based on receiving CSI-RS in BWPThe converted DFT space, and BWP dimension may refer to the number/>, based on the number of subbands included in BWPThe converted DFT space. Further, herein, "Z" may be expressed as the number of subbands included in BWP/>Number of subbands with received CSI-RS/>Is an integer of the ratio of (a).
Fig. 8A illustrates a wireless communication environment 800 for performing FD compression (e.g., as illustrated in fig. 8B-8E) by the second sub-transform block 423 of fig. 4. For example, the wireless communication environment 800 includes a case where CSI-RS is received in some consecutive subbands of BWP or a case where a CSI reporting band (e.g., a subband marked with "1" in a bit map of a channel state information reporting band (i.e., CSI reporting band) in fig. 8A) set as a subband of interest only for some consecutive subbands of BWP is received from a base station.
Referring to fig. 8A, the wireless communication environment 800 of fig. 8B to 8E assumes that the BWP 810 for communication between the base station and the wireless communication device 100 includes subbands (e.g., first to nth subbands SB 1 to) And some of the subbands 820 through which CSI-RS are received include/>Sub-bands (e.g., sub-band/>, where CSI-RS reception starts)Subband/>, to end of CSI-RS reception). In this case, some of the subbands 820 through which the CSI-RS is received may be consecutive subbands in the frequency domain.
Referring to fig. 8B and 8c, an example first oversampled DFT block (interchangeably, "oversampled DFT block") 830 in the bwp dimension and a second oversampled DFT block 840 in the CSI-RS dimension are shown.
In FIG. 8B, a first DFT input matrix of a first oversampled DFT block 830Can representA matrix of size, and input matrix/>, at a first DFTThe region 831 in which the CSI-RS is received can be defined byAnd (5) matrix representation.
The first oversampled DFT block 830 may use a first DFT functionTo perform BWP-dimensional FD compression. Here, the first DFT function/>A partial DFT function in BWP dimensions may be referred to.
First DFT functionCan represent/>A matrix of size (e.g., a partial DFT matrix). At the first DFT function/>The region 832 corresponding to the subband receiving the CSI-RS may include DFT columns rotated according to a preset period (e.g., a first DFT column 832-1, a second DFT column 832-2, … …, a z-th DFT column 832-z). In this case, the number of rotated DFT columns may be based on the number of subbands constituting BWP/>Number of subbands with which CSI-RS is receivedIs determined. After oversampling by the first oversampling DFT block 830, the FD base and NZC may be selected according to the method described in fig. 4.
In FIG. 8C, a second oversampled DFT block 840 may use a CSI-RS dimensional second DFT functionTo perform BWP-dimensional FD compression.
Second DFT input matrix of second oversampled DFT block 840841 Can be expressed asA matrix of size. Second DFT function/>, of second oversampled DFT block 840(E.g., first through z-th oversampled DFT functions 842-1 through 842-z) may represent/>A matrix of size. For example, each of the first through z-th oversampled DFT functions 842-1 through 842-z may includeOrthogonal matrices of size.
The second oversampled DFT block 840 may calculate the input matrix for the second DFT based on equation 4841 DFT transform results/>
[ Equation 4]
Here, R r is a matrix indicating a rotation index for each oversampled DFT function, and can be represented byDiagonal matrix of size. /(I)Is a matrix indicating a reception start position of the CSI-RS, and may be defined by a size/>Is comprised of a diagonal matrix of (a). For example, when/>BWP-dimensional DFT functions can be divided into/>When Z orthogonal matrices of size, this may refer to the method used to express each orthogonal matrix as/>Size/>Is used to rotate the matrix.
The rotation index and FD base selection block 843 may determine (or select) the rotation index and FD base of the CSI-RS dimension after DFT transform based on equation 5.
[ Equation 5]
The point DFT mapping block 845 may map the rotation index and FD base of the CSI-RS dimension to the BWP dimension based on equation 6.
[ Equation 6]
Here, Z means the number of subbands constituting BWPAnd the number of subbands over which the CSI-RS is receivedAnd r l may refer to the rotation index.
The NZC phase compensation block 847 may map NZCs of the selected CSI-RS dimension to the BWP dimension based on equation 7.
[ Equation 7]
When the number of subbands constituting BWPNumber of subbands with received CSI-RS/>When the ratio of (2) is an integer, from/>The second compressed data output by the point DFT mapping block 845 may skip the phase compensation process through the bypass path 848 (e.g., when the number of subbands making up BWP/>Number of subbands with received CSI-RS/>Where the ratio of (a) is an integer, bypass path 848 may be used) and generates channel information.
When performing FD compression based on a DFT transform block (e.g., the second oversampling DFT block 840) according to an embodiment, when preparing a DFT transform block (e.g., the first oversampling DFT block 830) according to a comparative embodiment, by performing low-dimensional FD compression, the efficiency of FD compression can be maximized by significantly reducing the overhead generated in FD compression processing.
Referring to fig. 8D, an embodiment of phase compensation of the start position of CSI-RS according to the second oversampling DFT block 840 of fig. 8C is shown. In fig. 8D, the configuration of fig. 8D (e.g., configurations 843, 845, 847, 848, 427) repeated with the previous figures may be replaced by the description of the previous figures.
In detail, the first case 853 and the second case 854 may be included as a method for phase compensation according to a start position of the CSI-RSAn example of an application time point.
The third oversampled DFT block 850 in the first case 853 may use a third DFT function of the CSI-RS dimensionTo perform BWP-dimensional FD compression. Here, the third DFT function/>May be referred to as an oversampled DFT function.
Third DFT input matrix for third oversampled DFT block 850851 Can be expressed as/> A matrix of size. Third DFT function/>, of third oversampled DFT block 850(E.g., first oversampled DFT function852-1 To z-th oversampled DFT function/>) Representation/>A matrix of size. For example, a first oversampled DFT function/>852-1 To z-th oversampled DFT function/>852-Z may each include/> Orthogonal matrices of size.
The third oversampled DFT block 850 may calculate an input matrix for the third DFT based on equation 8851 DFT conversion result/>
[ Equation 8]
Here, R r is a matrix indicating a rotation index for each oversampled DFT function, and can be represented byDiagonal matrix of size.
After the third oversampling DFT block 850, the rotation index and FD base may be selected according to the manner described in the second oversampling DFT block 840 of fig. 8C, and the rotation index and FD base of the CSI-RS dimension may be mapped to the BWP dimension.
NZC phase compensation block 847 is applicableThe starting position of the reception subband of the CSI-RS is indicated to compensate for the phase used to map NZC of CSI-RS dimension to BWP dimension. /(I)
Based on the method described above in fig. 4, the NZC selection and quantization block selects a dominant NZC among the NZCs mapped to the BWP dimension and performs quantization to generate channel information (e.g., UCI bit sequence). Here, in the first case 853, by applying before NZC selection and quantizationNZC may be selected based on DFT results mapped to BWP dimensions.
The oversampling DFT block 860 of the second case 854 is identical to the third oversampling DFT block 850, and rotates the index and FD base selection blocks andThe point DFT mapping blocks may be identical to those of the first case 853.
In the second case 854, however, unlike the first case 853,Can be applied after NZC selection and quantization. That is, in the second case 854, by applying after NZC selection and quantizationNZC may be selected based on DFT results in CSI-RS dimension, and mapping may be performed in BWP dimension.
The first case 853 and the second case 854 of fig. 8D haveBut the FD-group and NZC of the final chosen BWP dimension may be the same in each case.
Fig. 8E shows the number of subbands when BWP is constructedNumber of subbands with received CSI-RS/>When the ratio Z of (c) is not an integer, FD compression is performed by DFT without considering the influence of oversampling. In fig. 8E, the configuration of fig. 8E (e.g., configurations 845, 848, 426, 427) repeated with the previous figures may be replaced by the description of the previous figures.
The fourth oversampled DFT block 870 may use CSI-RS dimensional DFT functionsTo perform BWP-dimensional FD compression. Here, DFT function/>May refer to a function that does not consider the effects of the oversampling DFTs or that uses only some of the oversampling DFTs (e.g., r l is considered to be 1).
Fourth DFT input matrix for fourth oversampled DFT block 870871 May be expressed as/> A matrix of size.
The fourth oversampled DFT block 870 may calculate the input matrix for the fourth DFT based on equation 9871 DFT conversion result/>
[ Equation 9]
Here, DFT functionMay refer to a function that does not consider the effects of the oversampling DFTs or that uses only some of the oversampling DFTs (e.g., r l is considered to be 1).
In one embodiment, when the number of subbands making up BWPNumber of subbands with which CSI-RS is receivedWhere the ratio Z of (c) is not an integer, r l may be considered to be 1 (e.g., DFT function 872 of fig. 8E) without regard to the effect of the oversampling DFT. In this case, FD base in CSI-RS dimension after DFT transformation is removed/>, by removing from equation 5 of fig. 8C(I.e., not selecting a rotation index) is determined (or selected), and the FD base selected in the CSI-RS dimension may be mapped to the BWP dimension based on the above equation 6. In addition, the embodiment of phase compensation according to the start position of the CSI-RS of fig. 8D is applicable to the embodiment of fig. 8E.
Fig. 9 is a flowchart illustrating a method of operating a wireless communication device according to an example embodiment.
In detail, fig. 9 is a diagram for explaining an operation of performing BWP-dimensional FD compression (e.g., partial DFT application) by the baseband processor 110 (e.g., the third sub-transform block 424 of fig. 4) when the baseband processor 110 of the wireless communication device 100 of fig. 2 receives CSI-RS in some subbands of the entire BWP.
As previously defined, herein, the CSI-RS dimension may refer to DFT space based on a number conversion of some subbands in BWP receiving the CSI-RS, and the BWP dimension may refer to DFT space based on a number conversion of subbands included in BWP.
Referring to fig. 9, the operation of performing FD compression by applying the partial DFT may include operation S210, operation S220, operation S230, operation S240, operation S250, operation S260, and operation S270. Here, operation S210, operation S220, operation S230, operation S240, operation S260, and operation S270 correspond to operation S10, operation S20, operation S30, operation S40, operation S60, and operation S70 of fig. 4, respectively, and thus redundant descriptions thereof may be omitted.
In operation S250, the baseband processor 110 may generate second compressed data using a partial DFT function.
For example, the baseband processor 110 compresses SD-compressed first compressed data (hereinafter, FD compression) in the frequency domain using a partial DFT function to generate second compressed data. For example, the baseband processor 110 may select an FD base indicating an index of a column having a dominant value among second compressed data obtained by re-expressing the first compressed data in a partial DFT space. In addition, the baseband processor 110 may calculate absolute values of components included in second compressed data (e.g., matrix-form data) in the DFT conversion space, and select a preset number of NZCs according to the magnitude of the absolute values. The baseband processor 110 may quantize channel information including the selected FD base and NZC to display the channel information in a UCI bit sequence. A detailed description thereof will be described later with reference to fig. 10A and 10D.
In the wireless communication system according to the embodiment, the base station performs FD compression through the partial DFT according to the amount of channel information and adjusts the size of the CSI-RS allocation region so that there is an effect of improving resource efficiency by transmitting data only for specific wireless communication resources. In addition, the wireless communication apparatus according to the technical concept of the present invention can prevent degradation and distortion of CSI report contents due to interference through compression processing in a Frequency Domain (FD).
Fig. 10A to 10D are diagrams for explaining an FD compression operation by a third sub-transform block according to an example embodiment.
In detail, fig. 10A and 10D show diagrams for explaining FD compression operation by the third sub-conversion block 424 of the baseband processor 110 of fig. 4.
Fig. 10A shows a diagram for explaining a partial DFT function and a resulting DFT conversion result of operation S250 of fig. 9.
Referring to fig. 10A, a base station allocates to BWP 1001Sub-bands, and allocates/> to a region 1002 (e.g., some sub-band regions of BWP 1001) where CSI-RS is transmittedSub-bands (or frequency resources).
The baseband processor 110 may be based onGenerating partial DFT function/>, for FD compression, based on DFT basis of positions of subbands in a point DFT matrix (or DFT function) corresponding to a region where CSI-RS is receivedFor example, partial DFT function/>Can refer to having/>Partial DFT matrix of size. /(I)
Baseband processor 110 may calculate an input matrix for DFT based on equation 10Partial DFT conversion result of (2)
[ Equation 10]
The baseband processor 110 may be based on partial DFT conversion resultsIs based on equation 11 to calculate the optimized partial DFT transform result/>
[ Equation 11]
Here, the support (a) may point to a set of position indices of non-zero or significant coefficients of the quantity a. M may refer to parameters required for FD-base selection. For example, the baseband processor 110 may derive the partial DFT transform result based on equation 11 by an algorithm related to compressed sensing, sparse signal recovery, or sparse representationExamples of correlation algorithms may include a base tracking (BP) algorithm related to convex relaxation, a base tracking (BPIC) algorithm with inequality constraints, a base tracking denoising (BPDN) algorithm, and so on. Further, an Orthogonal Matching Pursuit (OMP) algorithm, a piecewise orthogonal matching pursuit (StOMP) algorithm, a regularized orthogonal matching pursuit (R-OMP) algorithm, a compressed sample matching pursuit (CoSaMP) algorithm, an Iterative Hard Threshold (IHT) algorithm, a two-phase threshold (TST) algorithm, a Subspace Pursuit (SP) algorithm, etc. associated with greedy pursuits may be used. Alternatively, a method of finding an optimized DFT result by replacing possible candidates from a violence point of view may be utilized.
FIG. 10B shows the partial DFT conversion result derived from equation 11 of FIG. 10A
Referring to fig. 10B, the baseband processor 110 matrix the DFT input based on equation 10 of fig. 101021 Execution is based on partial DFT function/>1022 To derive partial DFT transform result/>1023. For example, when DFT input matrix/>1021, When re-expressed as a partial DFT space, may appear as a column vector (or column index) 1024 with dominant values. Baseband processor 110 may determine (or select) column vector (or column index) 1024 as the FD base.
Fig. 10C illustrates a partial DFT function according to an embodiment when there are "inactive" subbands in the CSI reporting band received from the base station.
Referring to fig. 10c, dft input matrix1031 May be defined by/> Matrix composition of size, and partial DFT function/>1032 Can be made by/>Size DFT matrix.
Baseband processor 110 may calculate a partial DFT conversion result based on equation 12
[ Equation 12]
Baseband processor 110 may calculate an optimized partial DFT conversion result by an optimization equation similar to equation 11 of fig. 10B
Fig. 10D illustrates a partial DFT function according to another embodiment when there is an "inactive" subband in the CSI reporting band received from the base station.
If there are "inactive" subbands in the CSI reporting band received from the base station, baseband processor 110 may populate the DFT input matrix with particular values (e.g., "0")The "inactive" subbands 1043 of 1041 and derive optimized DFT transform results by re-expressing the padded results in DFT space in a manner similar to fig. 10B (e.g., equation 11).
Fig. 11 is a flowchart illustrating a method of operating a wireless communication device according to an example embodiment.
In detail, fig. 11 is a diagram for explaining an operation of performing BWP-dimensional FD compression (e.g., applying DFT after performing preprocessing) by the baseband processor 110 (e.g., the third sub-transform block 425 of fig. 4) when the baseband processor 110 of the wireless communication device 100 of fig. 2 receives CSI-RS in some subbands of the entire BWP.
As previously described, the "CSI-RS dimension" may refer to the number of some subbands based on which CSI-RS is received in BWPThe converted DFT space, and the "BWP dimension" may refer to the number/>, based on the number of subbands included in BWPThe converted DFT space.
Referring to fig. 11, the operation of performing FD compression by applying DFT after performing preprocessing may include operation S310, operation S320, operation S330, operation S340, operation S351, operation S352, operation S360, and operation S370. Here, operations S310 to S340 and operations S360 to S370 correspond to operations S10, S20, S30, S40, S60 and S70 of fig. 4, respectively, and thus redundant descriptions may be replaced with those of fig. 4.
In operation S351, the baseband processor 110 may perform preprocessing on the first compressed data according to a preset method. Here, the first compressed data may include a DFT input matrixAs a result of SD compression.
When the CSI-RS is received in some subbands of the entire BWP, baseband processor 110 may configure a BWP-dimensional DFT input matrix by performing preprocessing on the subbands not receiving the CSI-RSFor example, the preprocessing method may include a zero-padding method, a zero-interpolation method, a phase difference rotation method, a mirror image replication method, a repetition method, and the like. A detailed description of this will be described later in fig. 12A to 12G.
For example, baseband processor 110 may select an FD base that indicates that the first compressed data is to be re-expressed in DFT space (e.g., BWP-dimensional DFT input matrix) An index of a column having a dominant value therein. In addition, the baseband processor 110 may calculate absolute values of components included in second compressed data (e.g., matrix-form data) in the DFT conversion space, and select a preset number of NZCs according to the magnitude of the absolute values. The baseband processor 110 may quantize channel information including the selected FD base and NZC to display the channel information in UCI bit sequence.
In operation S352, the baseband processor 110 may generate second compressed data by using a DFT function having a size corresponding to the number of subbands constituting the BWP. For example, baseband processor 110 may input the matrix by a BWP-dimensional DFT configured via a preprocessing operation of operation 351The DFT transform is performed to perform BWP-dimensional FD compression.
The wireless communication apparatus according to the embodiment performs preprocessing on subbands not transmitting CSI-RS to configure a BWP-dimensional DFT input matrixSo that there is an effect of reducing overhead generated in FD compression through a preprocessing process while conforming to FD compression-related standards (e.g., performing FD compression through BWP-dimensional DFT transformation) of communication standards (e.g., 3gpp rel.16 to 17). In addition, the wireless communication apparatus according to the technical concept of the present invention can prevent distortion and distortion of CSI report contents due to interference through compression processing in a Frequency Domain (FD).
Fig. 12A to 12G are diagrams for explaining an FD compression operation by a fourth sub-transform block according to an exemplary example of the inventive concept.
In detail, fig. 12A and 12G show diagrams for explaining FD compression operation by the fourth sub-conversion block 425 of the baseband processor 110 of fig. 4. In fig. 12A and 12G, the horizontal axis may represent a subband region in the frequency domain, and the vertical axis may represent a precoding vector of the subband. For convenience of explanation, fig. 12A and 12G assume that CSI-RS is not allocated to a subband of a low frequency band, and the embodiments of fig. 12A and 12G are applicable even if the position of the subband to which CSI-RS is not allocated is changed.
Fig. 12A is a diagram for explaining a first preprocessing method and a second preprocessing method of operation S531 of fig. 11. In fig. 12A, it is assumed that a first region 1201 is a subband region to which CSI-RS is not allocated, and a second region 1202 is a subband region to which CSI-RS is allocated.
The first preprocessing method may include a linear interpolation method (e.g., a zero interpolation method).
For example, the baseband processor 110 may set the precoding vector 1203 of the first subband of the first region 1201 to a zero vector and configure the DFT input matrix by performing linear interpolation using the precoding vector 1204 of the first subband of the allocated CSI-RS of the second region 1202To this end, DFT input matrix/>Can be represented by equation 13.
[ Equation 13]
Here the number of the elements is the number,And N 1 may refer to the number of precoding vectors of the subbands to which the CSI-RS is not allocated, and N 1 (which is 0N 1＜N1) may refer to indexes of the subbands to which the CSI-RS is not allocated.
Although not shown in fig. 12A, the second preprocessing method may include a zero-padding method.
The baseband processor 110 may configure the DFT input matrix by filling the first region 1201 with a specific value (e.g., '0')With this approach, DFT input matrix/>May be represented by equation 14.
[ Equation 14]
Fig. 12B is a diagram for explaining a third preprocessing method of operation S531 of fig. 11. In fig. 12B, it is assumed that the first region 1211 is a subband region to which CSI-RS is not allocated, and the second region 1212 is a subband region to which CSI-RS is allocated.
The third preprocessing method may include a linear interpolation method using phase difference rotation (e.g., a zero interpolation method based on phase difference rotation).
For example, the baseband processor 110 may set the precoding vector 1213 of the first subband of the first region 1211 to a zero vector and configure the DFT input matrix by applying a phase difference rotation after performing linear interpolation using the precoding vector 1214 of the first subband of the allocated CSI-RS of the second region 1212In this regard, DFT input matrix/>Can be represented by equation 15.
[ Equation 15]
Here the number of the elements is the number,And N 1 refers to the number of precoding vectors of the subbands to which the CSI-RS is not allocated, and N 1 (which is 0.ltoreq.n 1＜N1) refers to the index of the subbands to which the CSI-RS is not allocated. R p (θ) may be defined as a phase difference rotation matrix based on equation 16, and R p (θ) a may be defined as a vector that increases the phase difference between the components of the a vector 1214 by θ based on equation 17.
[ Equation 16]
[ Equation 17]
In addition, equation 15The values are determined differently according to a phase difference rotation method, which may include 1) a random phase difference rotation method (e.g., a method of randomly selecting a value of θ), and 2) a phase difference cyclic shift method (e.g., application/>Θ 1＝(N1 -1) δ). Note that the baseband processor 110 according to the embodiment is not limited thereto; various alternative phase difference rotation schemes may be applied.
Fig. 12C is a diagram for explaining a fourth preprocessing method in operation S531 of fig. 11. In fig. 12C, it is assumed that the first region 1221 is a subband region to which CSI-RS is not allocated, and the second region 1222 is a subband region to which CSI-RS is allocated.
The fourth preprocessing method may include applying an average linear interpolation method.
For example, the baseband processor 110 calculates an average vector of precoding vectors of the subbands of the second region 1222And calculates a precoding vector of the first sub-band 1223 to which the CSI-RS is not allocated; baseband processor 110 may then configure the DFT input matrix by performing linear interpolation using the precoding vectors of the first sub-band 1224 of the allocated CSI-RS of the second region 1222In this case, DFT input matrix/>May be represented by equation 18 and although not shown, phase difference rotation may also be applied.
[ Equation 18]
Wherein v A = a-m
Here the number of the elements is the number,And N 1 may refer to the number of precoding vectors of the subbands to which the CSI-RS is not allocated, and N 1 (which is 0N 1＜N1) may refer to indexes of the subbands to which the CSI-RS is not allocated. Average vector/>May be calculated based on equation 19.
[ Equation 19]
Fig. 12D is a diagram for explaining a fifth preprocessing method of operation S531 of fig. 11. In fig. 12D, it is assumed that the first region 1231 is a subband region to which CSI-RS is not allocated, and the second region 1232 is a subband region to which CSI-RS is allocated.
The fifth preprocessing method may include a mirror copy method.
For example, the baseband processor 110 copies the precoding vector mirror image of the second region 1232 to the first region 1231 based on the first sub-band 1234 of the second region 1232 and configures the DFT input matrixAt this time, DFT input matrix/>May be represented by equation 20.
[ Equation 20]
Here the number of the elements is the number,And N 1 may refer to the number of precoding vectors of the subbands to which the CSI-RS is not allocated, and N and m (which is 0.ltoreq.n.ltoreq.m < N 1) may refer to indexes of the subbands to which the CSI-RS is not allocated.
Fig. 12E is a diagram for explaining a sixth preprocessing method of operation S531 of fig. 11. In fig. 12E, it is assumed that the first region 1241 is a subband region to which CSI-RS is not allocated, and the second region 1242 is a subband region to which CSI-RS is allocated.
The sixth pretreatment method may include a repeat method.
For example, the baseband processor 110 may configure the DFT input matrix by repeatedly applying the precoding vector of the second region 1232 to the first region 1231At this time, DFT input matrix/>Can be represented by equation 21.
[ Equation 21]
Here the number of the elements is the number,And N 1 refers to the number of precoding vectors of the subbands to which the CSI-RS is not allocated, and N may be defined as/>
Fig. 12F shows a diagram for explaining a seventh preprocessing method of operation S531 of fig. 11. In fig. 12F, it is assumed that the first region 1251 is a subband region to which CSI-RS is not allocated, and the second region 1252 is a subband region to which CSI-RS is allocated.
The seventh pretreatment method may include a repeat method.
For example, the baseband processor 110 may repeatedly apply precoding vectors of the second region 1252 to the first region 1251 and configure the DFT input matrix by filling a specific value (e.g., "0") into the remaining sub-band region 1253 of the first region 1251At this time, DFT input matrix/>May be represented by equation 22.
[ Equation 22]
Here the number of the elements is the number,And N 1 refers to the number of precoding vectors of the subbands to which the CSI-RS is not allocated, and N may be defined as/>
Fig. 12G shows a diagram for explaining an eighth preprocessing method of operation S531 of fig. 11. In fig. 12G, the configuration of fig. 12G (e.g., configurations 848, 410, 426, 427, 430) repeated with the above figures may be replaced by the description of the above figures.
The eighth pre-processing method may include a Wideband (WB) pre-coding method.
After SD compression, the baseband processor 110 may replace the matrix V n corresponding to the channel characteristic information of the nth sub-band with the wideband matrix V WB. For example, when the DFT block 1260 of the baseband processor 110 compresses the matrix of the first layer of the CSI-RS region in the frequency domainWhen, if the number of FD groups effectively representing the frequency domain characteristics (e.g., change in frequency, etc.) of the matrix is identified as insufficient, the matrix V WB,l of the first layer in the wideband view may be quantized and transmitted to the base station instead of compressing and transmitting the matrix/>, of the first layer of the CSI-RS regionHere, V WB,l may include all CSI-RS channel information matrices whose subband bit map is "active" or matrices after SD compression is performed by base station precoding determined by the terminal.
For example, the DFT block 1260 of the baseband processor 110 may determine (or select) a representative channel in a subband to which CSI-RS is allocated, and perform FD compression on the entire BWP subband after copying channel values of the representative channel to channel values of all subbands of the entire BWP. For another example, the average value of the precoding vectors of the second region may be copied to the first region.
Fig. 13 is a block diagram illustrating an electronic device according to an example embodiment.
The wireless communication device 1300 of fig. 13 may correspond to the wireless communication device 100 of fig. 1.
Referring to fig. 13, the electronic device may include a memory 1310, a processor unit 1320, an input/output control unit 1340, a display unit 1350, an input device 1360, and a communication processing unit 1390. Here, a plurality of memories 1310 may exist. A brief discussion of each component follows.
The memory 1310 may include a program storage unit 1311 for storing a program for controlling the operation of the electronic device and a data storage unit 1312 for storing data generated during program execution. Data storage unit 1312 may store data required for operation of application 1313 and CSI compression setup program 1314. Program storage unit 1311 may include application programs 1313 and CSI compression setup programs 1314. Here, the program included in the program storage unit 1311 may be represented as an instruction set.
The applications 1313 include applications operating in an electronic device. That is, the application programs 1313 may include instructions for an application driven by the processor 1322. According to example embodiments, when CSI-RS is allocated to only some subbands in the entire BWP, CSI compression configuration procedure 1314 may perform frequency domain compression using DFT functions (e.g., DFT functions in CSI-RS dimensions, partial DFT functions, oversampled DFT functions, etc.) based on channel characteristic information of the subbands to which CSI-RS is allocated.
Peripheral interface 1323 may control the connection between the input/output peripheral devices of the base station and processor 1322 and memory interface 1321. Processor 1322 controls the base station to provide the corresponding service using at least one software program. In this case, the processor 1322 may execute at least one program stored in the memory 1310 to provide a service corresponding to the program.
The input/output control unit 1340 may provide an interface between input/output devices (such as the display unit 1350 and the input device 1360) and the peripheral device interface 1323. The display unit 1350 displays status information, input characters, moving images, and still images. For example, the display unit 1350 may display application information driven by the processor 1322.
The input device 1360 may provide input data generated through selection of an electronic device to the processor unit 1320 through the input/output control unit 1340. In this case, the input device 1360 may include a keypad including at least one hardware button and a touch pad for sensing touch information. For example, the input device 1360 may provide touch information to the processor 1322 through the input/output controller 1340, such as touches sensed by a touch panel, touch movements, and touch releases. The electronic device may include a communication processing unit 1390 that performs communication functions for voice communication and data communication. According to an example embodiment, communication processing unit 1390 may include a plurality of antenna modules 1392 to support millimeter-wave band communications.
While the present inventive concept has been particularly shown and described with reference to embodiments thereof, it will be understood that various changes in form and details may be made therein without departing from the spirit and scope of the appended claims.
Claims (20)
1. A method of operation of a wireless communication device, the method comprising:
receiving a channel state information reference signal (CSI-RS) from a base station;
generating channel information by estimating a channel between the wireless communication apparatus and the base station based on the CSI-RS; and
The channel information is reported to the base station,
Wherein generating the channel information comprises:
generating first compressed data by compressing channel characteristic information of a subband receiving the CSI-RS in a spatial domain;
generating second compressed data by compressing the first compressed data in a frequency domain using a first discrete fourier transform, DFT, function, wherein the first DFT function has a size corresponding to a number of subbands for receiving CSI-RS in a bandwidth portion, BWP, for communication with the base station; and
The channel information is generated based on the second compressed data.
2. The method of claim 1, wherein generating second compressed data further comprises: when bit map information indicating subbands of interest of a base station is received from the base station, second compressed data is generated by compressing the first compressed data in a frequency domain using a second DFT function having a size corresponding to the number of subbands of interest.
3. The method of claim 1, wherein when a ratio of the number of subbands constituting the BWP to the number of subbands through which the CSI-RS is received is an integer, generating second compressed data further comprises:
Generating an oversampled DFT function by applying at least one of a rotation index and a position indication matrix of the CSI-RS to the first DFT function; and
The second compressed data is generated by compressing the first compressed data in the frequency domain using an oversampled DFT function.
4. A method according to claim 3, wherein the number of rotation indexes is determined based on a ratio of the number of subbands constituting the BWP to the number of subbands through which CSI-RS is received.
5. The method of claim 3, wherein when a ratio of the number of subbands constituting the BWP to the number of subbands through which the CSI-RS is received is an integer, generating the channel information further comprises:
Selecting a frequency domain FD base corresponding to a reception region of the CSI-RS based on the second compressed data; and
The FD base is mapped to correspond to the BWP region.
6. The method of claim 5, wherein mapping FD groups further comprises:
calculating a value by adding a rotation index to an FD base multiplied by a ratio of the number of subbands constituting the BWP to the number of subbands through which CSI-RS is received; and
The value is mapped to the FD base corresponding to the BWP region.
7. The method of claim 5, wherein when a ratio of the number of subbands constituting the BWP to the number of subbands through which CSI-RS is received is an integer, generating the channel information further comprises:
selecting a non-zero coefficient NZC based on a matrix composed of column vectors corresponding to the first compressed data and FD base; and
The NZC is mapped to correspond to a BWP region.
8. The method of claim 7, wherein selecting the NZC comprises: the NZC is selected based on absolute values of elements included in a matrix composed of column vectors corresponding to the first compressed data and the FD base.
9. The method of claim 1, wherein generating the second compressed data when a ratio of the number of subbands constituting the BWP to the number of subbands through which the CSI-RS is received is not an integer comprises:
generating a fourth DFT function by applying the position indication matrix of the CSI-RS to the first DFT function; and
The second compressed data is generated by compressing the first compressed data in the frequency domain using a fourth DFT function.
10. A method of operation of a wireless communication device, the method comprising:
receiving a channel state information reference signal (CSI-RS) from a base station;
generating channel information by estimating a channel between the wireless communication apparatus and the base station based on the CSI-RS; and
The channel information is reported to the base station,
Wherein generating the channel information comprises:
generating first compressed data by compressing channel characteristic information of a subband receiving the CSI-RS in a spatial domain;
generating second compressed data by compressing the first compressed data in a frequency domain using a first partial discrete fourier transform, DFT, function, wherein the first partial DFT function consists of a column domain corresponding to a subband constituting a bandwidth portion, BWP, for communication with the base station and a row domain corresponding to a subband receiving the CSI-RS; and
The channel information is generated based on the second compressed data.
11. The method of claim 10, wherein generating second compressed data comprises: when bit map information indicating a subband of interest of a base station is received from the base station, second compressed data is generated by compressing the first compressed data in a frequency domain using a second partial DFT function, wherein the second partial DFT function consists of a column domain corresponding to a region of the subband constituting the BWP and a row domain corresponding to the subband of interest.
12. A method of operation of a wireless communication device, the method comprising:
receiving a channel state information reference signal (CSI-RS) from a base station;
generating channel information by estimating a channel between the wireless communication apparatus and the base station based on the CSI-RS; and
The channel information is reported to the base station,
Wherein generating the channel information comprises:
generating first compressed data by compressing channel characteristic information of a subband receiving the CSI-RS in a spatial domain;
Performing preprocessing on subbands not receiving CSI-RS among subbands of a bandwidth part BWP for communication with a base station according to a preset method;
Generating second compressed data by compressing the preprocessed first compressed data in a frequency domain using a discrete fourier transform DFT function having a size corresponding to the number of subbands constituting the BWP; and
The channel information is generated based on the second compressed data.
13. The method of claim 12, wherein the preprocessing uses a first preprocessing method for padding subbands of the BWP, which do not receive CSI-RS, with a preset specific value.
14. The method of claim 12, wherein the preprocessing uses a second preprocessing method for performing linear interpolation on a subband of the BWP that does not receive CSI-RS.
15. The method of claim 12, wherein the preprocessing uses a third preprocessing method for performing linear interpolation and phase difference rotation on a subband of the BWP, which does not receive CSI-RS.
16. The method of claim 12, wherein the preprocessing comprises: calculating an average value of precoding vectors of subbands of the received CSI-RS in the subbands of the BWP; and
A fourth preprocessing method for performing linear interpolation based on the average value of the precoding vectors is used.
17. The method of claim 12, wherein the preprocessing uses a fifth preprocessing method, wherein the fifth preprocessing method copies precoding vector images of the sub-bands of the BWP that receive CSI-RS to sub-bands that do not receive CSI-RS.
18. The method of claim 12, wherein the preprocessing uses a sixth preprocessing method, wherein the sixth preprocessing method copies precoding vectors of subbands receiving CSI-RS among the subbands of the BWP to subbands not receiving CSI-RS.
19. The method of claim 12, wherein the preprocessing uses a seventh preprocessing method in which precoding vectors of subbands receiving CSI-RS are copied to subbands not receiving CSI-RS among the subbands of the BWP, and the copied remaining subbands are padded with a preset specific value.
20. The method of claim 12, wherein the preprocessing uses an eighth preprocessing method, wherein the eighth preprocessing method copies an average value of precoding vectors of subbands receiving CSI-RS to subbands of the BWP that do not receive CSI-RS.
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