WO2024099480A1 - Low-complexity codebook design - Google Patents

Low-complexity codebook design Download PDF

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Publication number
WO2024099480A1
WO2024099480A1 PCT/CN2024/074097 CN2024074097W WO2024099480A1 WO 2024099480 A1 WO2024099480 A1 WO 2024099480A1 CN 2024074097 W CN2024074097 W CN 2024074097W WO 2024099480 A1 WO2024099480 A1 WO 2024099480A1
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WIPO (PCT)
Prior art keywords
layer
group
indicator
bases
common
Prior art date
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PCT/CN2024/074097
Other languages
French (fr)
Inventor
Guangyu JIANG
Bo Gao
Minqiang ZOU
Original Assignee
Zte Corporation
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Publication date
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Priority to PCT/CN2024/074097 priority Critical patent/WO2024099480A1/en
Publication of WO2024099480A1 publication Critical patent/WO2024099480A1/en

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Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B7/00—Radio transmission systems, i.e. using radiation field
    • H04B7/02—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas
    • H04B7/04—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas
    • H04B7/0413—MIMO systems
    • H04B7/0456—Selection of precoding matrices or codebooks, e.g. using matrices antenna weighting
    • H04B7/0478—Special codebook structures directed to feedback optimisation
    • H04B7/048—Special codebook structures directed to feedback optimisation using three or more PMIs
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B7/00—Radio transmission systems, i.e. using radiation field
    • H04B7/02—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas
    • H04B7/04—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas
    • H04B7/0413—MIMO systems
    • H04B7/0456—Selection of precoding matrices or codebooks, e.g. using matrices antenna weighting
    • H04B7/046—Selection of precoding matrices or codebooks, e.g. using matrices antenna weighting taking physical layer constraints into account
    • H04B7/0469—Selection of precoding matrices or codebooks, e.g. using matrices antenna weighting taking physical layer constraints into account taking special antenna structures, e.g. cross polarized antennas into account
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B7/00—Radio transmission systems, i.e. using radiation field
    • H04B7/02—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas
    • H04B7/10—Polarisation diversity; Directional diversity
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B7/00—Radio transmission systems, i.e. using radiation field
    • H04B7/02—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas
    • H04B7/022—Site diversity; Macro-diversity
    • H04B7/024—Co-operative use of antennas of several sites, e.g. in co-ordinated multipoint or co-operative multiple-input multiple-output [MIMO] systems

Definitions

  • This patent document is directed generally to wireless communications.
  • LTE Long-Term Evolution
  • 3GPP 3rd Generation Partnership Project
  • LTE-A LTE Advanced
  • 5G The 5th generation of wireless system, known as 5G, advances the LTE and LTE-A wireless standards and is committed to supporting higher data rates, large number of connections, ultra-low latency, high reliability, and other emerging business needs.
  • Low-complexity codebook structures are disclosed to improve precoding matrix indicator (PMI) reporting accuracy and reduce reporting overhead.
  • One disclosed codebook structure is based on spatial-domain (SD) bases only.
  • Another disclosed codebook structure is based on both SD bases and frequency-domain (FD) bases.
  • a first example wireless communication method includes receiving, by a wireless device, a channel state information (CSI) reporting configuration signaling and a reference signal (RS) for a channel measurement.
  • the method further includes transmitting, by the wireless device, a CSI, where the CSI is determined based on the CSI reporting configuration signaling and the RS for the channel measurement, where the CSI includes at least one of a CSI-RS resource indicator (CRI) , a rank indicator (RI) , a layer indicator (LI) , a precoding matrix indicator (PMI) , or a channel quality indicator (CQI) , and where the PMI indicates a v-layer precoding matrix.
  • CRI CSI-RS resource indicator
  • RI rank indicator
  • LI layer indicator
  • PMI precoding matrix indicator
  • CQI channel quality indicator
  • a second example wireless communication method includes transmitting, by a network device, a channel state information (CSI) reporting configuration signaling and a reference signal (RS) for a channel measurement.
  • the method further includes receiving, by the network device, a CSI, where the CSI is determined based on the CSI reporting configuration signaling and the RS for the channel measurement, where the CSI includes at least one of a CSI-RS resource indicator (CRI) , a rank indicator (RI) , a layer indicator (LI) , a precoding matrix indicator (PMI) , or a channel quality indicator (CQI) , and where the PMI indicates a v-layer precoding matrix.
  • CRI CSI-RS resource indicator
  • RI rank indicator
  • LI layer indicator
  • PMI precoding matrix indicator
  • CQI channel quality indicator
  • a device that is configured or operable to perform the above-described methods.
  • the device includes at least one processor configured to implement the above-described methods.
  • the above-described methods are embodied in the form of processor-executable code and stored in a non-transitory computer-readable storage medium.
  • the code included in the computer readable storage medium when executed by a processor, causes the processor to implement the methods described in this patent document.
  • FIG. 1 is an example flowchart for transmitting a channel state information (CSI) .
  • CSI channel state information
  • FIG. 2 is an example flowchart for receiving a CSI.
  • FIG. 3 illustrates an example block diagram of a hardware platform that may be a part of a network device or a wireless device.
  • FIG. 4 illustrates example wireless communication including a Base Station (BS) and User Equipments (UEs) based on some implementations of the disclosed technology.
  • BS Base Station
  • UEs User Equipments
  • the present patent document describes low-complexity codebook structures that improve precoding matrix indicator (PMI) reporting accuracy and reduce reporting overhead.
  • PMI precoding matrix indicator
  • a user equipment In a multiple-input-multiple-output (MIMO) communication system operated in a frequency-division-duplexing (FDD) mode, a user equipment (UE) typically measures the downlink (DL) channel state information (CSI) through a DL reference signal (RS) and feeds back the CSI to a base station (BS) .
  • the CSI can include at least one of: a CSI-RS resource indicator (CRI) , a rank indicator (RI) , a layer indicator (LI) , a precoding matrix indicator (PMI) , and a channel quality indicator (CQI) .
  • CRI channel state information
  • RI rank indicator
  • LI layer indicator
  • PMI precoding matrix indicator
  • CQI channel quality indicator
  • PMI reflects the DL channel response and costs the highest reporting overhead.
  • PMI reporting is based on a predefined codebook.
  • the reporting accuracy and overhead are determined by the codebook structure.
  • the method includes the following embodiments:
  • Embodiment 1 Codebook structure based on spatial-domain (SD) bases only;
  • Embodiment 2 Codebook structure based on both SD bases and frequency-domain (FD) bases.
  • the 3rd Generation Partnership Project (3GPP) protocols specify mainly two types of codebooks, namely Type-I and Type-II/enhanced Type-II (e-Type-II) codebooks for PMI reporting.
  • the 3GPP protocols further introduce two types of enhanced eType-II codebooks, namely eType-II codebook for coherent joint transmission (CJT) and eType-II codebook for predicted PMI, which support PMI reporting in CJT and medium/high speed scenarios, respectively.
  • CJT coherent joint transmission
  • eType-II codebook for predicted PMI which support PMI reporting in CJT and medium/high speed scenarios, respectively.
  • Type-I codebook has a simple structure and costs low reporting overhead
  • Type-II/eType-II codebook has a complex structure and costs high reporting overhead.
  • Type-I cannot meet the demand of high-resolution PMI feedback, and hence shows poor performance.
  • Type-II/eType-II codebook suffers from unacceptable high reporting overhead and high implementation complexity. Therefore, a usable codebook with acceptable performance and reporting overhead is urgently needed.
  • a low-complexity codebook based on the Type-II/eType-II codebook framework. The proposed new codebook enables low-complexity PMI calculation and low-overhead PMI reporting, and meanwhile guarantees the precoding performance.
  • UE can be equivalent to wireless communication device
  • BS can be equivalent to gNB (the next Generation Node B) , wireless network device, or TRP (Transmission and Reception Point) ;
  • antenna port can be equivalent to “BS antenna port” , or “CSI-RS (Channel State Information Reference Signal) antenna port” ;
  • “higher layer parameter” can be equivalent to “RRC (Radio Resource Control) parameter” , “Physical Downlink Control Channel (PDCCH) ” , or “Downlink control information (DCI) ” ;
  • SD basis can be equivalent to v l, m or
  • the quantities v l, m and corresponding to (l, m) are defined in clause 5.2.2.2.1 of TS 38.214 as
  • N 1 N 2 are defined in clause 5.2.2.2.1 of TS 38.214
  • the number of antenna ports P 2N 1 N 2
  • O 1 O 2 are oversampling factors defined in clause 5.2.2.2.1 of TS 38.214.
  • the FD (Frequency Domain) basis corresponding to and l is defined in clause 5.2.2.2.5 of TS 38.214 as
  • N 3 is the number of total precoding matrices
  • M v is the number of selected FD bases
  • l is the layer index or layer group index
  • coefficient can be equivalent to “combination coefficient” ;
  • amplitude can be equivalent to “amplitude coefficient” , or “coefficient amplitude” ;
  • phase can be equivalent to “phase coefficient” , or “coefficient phase” .
  • UE receives CSI reporting configuration signaling and RS for channel measurement from BS;
  • the UE determines CSI based on the CSI reporting configuration signaling and RS for channel measurement, where the CSI contains at least of CRI, RI, LI, PMI, and CQI, and the PMI indicates a v-layer precoding matrix;
  • UE sends the CSI to BS.
  • Embodiment 1 discloses a codebook structure based on SD bases only.
  • the PMI can include a number of SD bases (or an indicator of a number of SD bases) , a number of combination coefficients (or an indicator of a number of combination coefficients) , and a polarization coefficient (or an indicator of a polarization coefficient) .
  • Each layer group can include X or less layers.
  • the number of layer groups is
  • X can be a configurable higher layer parameter.
  • X can be a predefined value, e.g., 1, 2, or 4.
  • the SD bases can be layer common/specific or layer group common/specific. Within each layer group, the SD bases are common across different layers.
  • the number of SD bases can be L.
  • L can be a configurable higher layer parameter.
  • Candidate value of L can be ⁇ 2, 4, 6, 8 ⁇ .
  • the ith SD basis among the L SD bases can be denoted as where can be expressed as
  • ⁇ q 1 , q 2 ⁇ , 0 ⁇ q 1 ⁇ O 1 -1, 0 ⁇ q 2 ⁇ O 1 -1 are indicated by a combinatorial number included in the PMI.
  • the polarization coefficient can be layer common/specific or layer group common/specific. Within each layer group, the polarization coefficient is common across different layers.
  • the polarization coefficient can be subband specific/common.
  • the polarization coefficient ⁇ l corresponding to lth layer or layer group can be expressed as
  • the PMI includes L combination coefficients. Within each layer group, the L combination coefficients are common across different layers.
  • the combination coefficient corresponding to the lth layer or layer group and the ith SD basis a l, i can be expressed as
  • the greatest combination coefficient among the L combination coefficients can be indicated by an integer belonging to ⁇ 0, 1, . . ., L-1 ⁇ . This integer is included in the PMI and reported to BS. The greatest combination coefficient is not reported.
  • the wideband amplitude is subband common.
  • the subband amplitude is subband specific. can be fixed as 1, then can be not reported.
  • the amplitude can be fixed as 1, then and can be not reported.
  • the combination coefficient equaling to 1 among the L combination coefficients can be indicated by an integer belonging to ⁇ 0, 1, . . ., L-1 ⁇ . This integer is included in the PMI and reported to BS. The combination coefficient equaling to 1 is not reported.
  • the phase can be subband specific/common.
  • the precoding matrix indicated by the PMI, or the codebook structure can be expressed as
  • W l is the precoding matrix corresponding to the lth layer or layer group.
  • the precoding matrix to the l-th layer or l-th layer group can be expressed in one of the following formulas:
  • Embodiment 2 discloses a codebook structure based on both SD bases and FD bases.
  • the PMI can include a number of SD bases (or an indicator of a number of SD bases) , a number of FD bases (or an indicator of a number of FD bases) , a number of combination coefficients (or an indicator of a number of combination coefficients) , and a polarization coefficient (or an indicator of a polarization coefficient) .
  • Each layer group can include X or less layers.
  • the number of layer groups is
  • X can be a configurable higher layer parameter.
  • X can be a predefined value, e.g., 1, 2, or 4.
  • the SD bases can be layer common/specific or layer group common/specific. Within each layer group, the SD bases are common across different layers.
  • the number of SD bases can be L.
  • L can be a configurable higher layer parameter.
  • Candidate value of L can be ⁇ 2, 4, 6, 8 ⁇ .
  • the ith SD basis among the L SD bases can be denoted as where can be expressed as
  • ⁇ q 1 , q 2 ⁇ , 0 ⁇ q 1 ⁇ O 1 -1, 0 ⁇ q 2 ⁇ O 1 -1 are indicated by a combinatorial number included in the PMI.
  • the FD bases can be layer specific/common, or layer group specific/common. Within each layer group, the FD bases are common across different layers.
  • the polarization coefficient can be layer common/specific or layer group common/specific. Within each layer group, the polarization coefficient is common across different layers.
  • the polarization coefficient can be subband specific/common.
  • the polarization coefficient ⁇ l corresponding to lth layer or layer group can be expressed as
  • the PMI includes L ⁇ M v combination coefficients.
  • the L ⁇ M v combination coefficients are common across different layers.
  • the combination coefficient corresponding to the lth layer or layer group, the ith SD basis, and the fth FD basis and the ith, a l, i, f can be expressed as
  • p l, i, f is the amplitude, and is the phase, where can be 1, 2, 3, or 4.
  • the greatest combination coefficient can be indicated by an integer belonging to ⁇ 0, 1, . . ., L-1 ⁇ and an integer belonging to ⁇ 0, 1, . . ., M v -1 ⁇ . These two integers are included in the PMI and reported to BS. The greatest combination coefficient can be not reported.
  • the amplitude p l, i, f can be fixed as 1, then p l, i, f can be not reported.
  • the combination coefficient equaling to 1 among the L ⁇ M v combination coefficients can be indicated by an integer belonging to ⁇ 0, 1, . . ., L-1 ⁇ and an integer belonging to ⁇ 0, 1, . . ., M v -1 ⁇ , these two integers are included in the PMI and reported to BS.
  • Embodiment 1 gives a codebook structure based on SD bases only, while embodiment 2 gives a codebook structure based on both SD bases and FD bases.
  • FIG. 1 is an example flowchart for transmitting a channel state information (CSI) .
  • Operation 102 includes receiving, by a wireless device, a channel state information (CSI) reporting configuration signaling and a reference signal (RS) for a channel measurement.
  • Operation 104 includes transmitting, by the wireless device, a CSI, where the CSI is determined based on the CSI reporting configuration signaling and the RS for the channel measurement, where the CSI includes at least one of a CSI-RS resource indicator (CRI) , a rank indicator (RI) , a layer indicator (LI) , a precoding matrix indicator (PMI) , or a channel quality indicator (CQI) , and where the PMI indicates a v-layer precoding matrix.
  • CRI CSI-RS resource indicator
  • RI rank indicator
  • LI layer indicator
  • PMI precoding matrix indicator
  • CQI channel quality indicator
  • v is a number greater than 1, and the method is implemented for a multi-layer scheme.
  • the method can be implemented according to Embodiment 1 and Embodiment 2.
  • performing further steps of the method can be based on a better system performance than a legacy protocol.
  • the PMI includes at least one of the following: a number of spatial domain (SD) bases corresponding to each layer or layer group; an indicator of the number of SD bases corresponding to each layer or layer group; a number of combination coefficients corresponding to each layer or layer group; an indicator of the number of combination coefficients corresponding to each layer or layer group; a number of polarization coefficients corresponding to each layer or layer group; or an indicator of the number of polarization coefficients corresponding to each layer or layer group.
  • SD spatial domain
  • each layer group includes X or less layers, where a number of layer groups is and where X is a configurable higher layer parameter or a predefined value including 1, 2, or 4.
  • the SD bases are layer-common, layer-specific, layer-group-common, or layer-group-specific, and within each layer group, the SD bases are common across different layers.
  • the number of SD bases is L, where L is a configurable higher layer parameter including 2, 4, 6, or 8.
  • the polarization coefficients are layer-common, layer-specific, layer-group-common, layer-group-specific, subband-common, or subband-specific, and within each layer group, the polarization coefficients are common across different layers.
  • a polarization coefficient ⁇ l corresponding to an lth layer or layer group is where Q ⁇ is 1, 2, 3, or 4.
  • the PMI includes L combination coefficients, and within each layer group, the L combination coefficients are common across different layers.
  • a greatest combination coefficient among L combination coefficients is indicated by a first integer belonging to ⁇ 0, 1, . . ., L-1 ⁇ , where the first integer is reported in the PMI, and where the greatest combination coefficient is not reported.
  • a combination coefficient a l, i corresponding to an lth layer or layer group and an ith SD basis is determined by at least one of or wherein is a wideband amplitude, is a subband amplitude, and is a phase, and wherein is 1, 2, 3, or 4.
  • the wideband amplitude is subband-common
  • the subband amplitude is subband-specific
  • the phase is subband-common or subband-specific, where at least one of the following applies: the combination coefficient a l, i is determined by and as the combination coefficient a l, i is determined by as thecombination coefficient a l, i is determined by as acombination coefficient that is equal to 1 among L combination coefficients is indicated by a second integer belonging to ⁇ 0, 1, . . ., L-1 ⁇ , the second integer is reported in the PMI, and the combination coefficient that is equal to 1 is not reported; the combination coefficient a l, i is determined by and as or the combination coefficient a l, i is determined by as
  • a precoding matrix indicated by the PMI or a codebook structure is where W l is a precoding matrix corresponding to an lth layer or layer group.
  • the precoding matrix corresponding to the l-th layer or layer group is determined by at least one of the following: spatial domain (SD) bases corresponding to the l-th layer or layer group; combination coefficients corresponding to the l-th layer or layer group; or polarization coefficients corresponding to the l-th layer or layer group.
  • SD spatial domain
  • the precoding matrix corresponding to the l-th layer or layer group is at least one of the following:
  • SD ith spatial domain
  • the PMI includes at least one of the following: a number of spatial domain (SD) bases corresponding to each layer or layer group; an indicator of the number of SD bases corresponding to each layer or layer group; a number of frequency domain (FD) bases corresponding to each layer or layer group; an indicator of the number of FD bases corresponding to each layer or layer group; a number of combination coefficients corresponding to each layer or layer group; an indicator of the number of combination coefficients corresponding to each layer or layer group; a number of polarization coefficients corresponding to each layer or layer group; or an indicator of the number of polarization coefficients corresponding to each layer or layer group.
  • SD spatial domain
  • FD frequency domain
  • each layer group includes X or less layers, where a number of layer groups is and where X is a configurable higher layer parameter or a predefined value including 1, 2, or 4.
  • the SD bases and the FD bases are layer-common, layer-specific, layer-group-common, or layer-group-specific, and within each layer group, the SD bases and the FD bases are common across different layers.
  • the number of SD bases is L, where L is a configurable higher layer parameter including 2, 4, 6, or 8.
  • the polarization coefficients are layer-common, layer-specific, layer-group-common, layer-group-specific, subband-common, or subband-specific, and within each layer group, the polarization coefficients are common across different layers.
  • a polarization coefficient ⁇ l corresponding to an lth layer or layer group is where Q ⁇ is 1, 2, 3, or 4.
  • the PMI includes L ⁇ M v combination coefficients, where M v is a number of FD bases, and where within each layer group, the L ⁇ M v combination coefficients are common across different layers.
  • a greatest combination coefficient is indicated by a first integer belonging to ⁇ 0, 1, . . ., L-1 ⁇ and a second integer belonging to ⁇ 0, 1, . . ., M v -1 ⁇ , where the first and second integers are reported in the PMI, and where the greatest combination coefficient is not reported.
  • a combination coefficient a l, i, f corresponding to an lth layer or layer group, an ith SD basis, and an fth FD basis is determined by at least one of p l, i, f or wherein p l, i, f is an amplitude and is a phase, and wherein is 1, 2, 3, or 4.
  • the combination coefficient a l,i, f is determined by p l, i, f and as the combination coefficient a l, i, f is determined by as the combination coefficient a l, i, f is determined by as acombination coefficient that is equal to 1 among L ⁇ M v combination coefficients is indicated by a third integer belonging to ⁇ 0, 1, . . ., L-1 ⁇ and a fourth integer belonging to ⁇ 0, 1, . .
  • SD spatial domain
  • FD frequency domain
  • SD spatial domain
  • FIG. 2 is an example flowchart for receiving a channel state information (CSI) .
  • Operation 202 includes transmitting, by a network device, a channel state information (CSI) reporting configuration signaling and a reference signal (RS) for a channel measurement.
  • Operation 204 includes receiving, by the network device, a CSI, where the CSI is determined based on the CSI reporting configuration signaling and the RS for the channel measurement, where the CSI includes at least one of a CSI-RS resource indicator (CRI) , a rank indicator (RI) , a layer indicator (LI) , a precoding matrix indicator (PMI) , or a channel quality indicator (CQI) , and where the PMI indicates a v-layer precoding matrix.
  • CRI CSI-RS resource indicator
  • RI rank indicator
  • LI layer indicator
  • PMI precoding matrix indicator
  • CQI channel quality indicator
  • v is a number greater than 1, and the method is implemented for a multi-layer scheme.
  • the method can be implemented according to Embodiment 1 and Embodiment 2.
  • performing further steps of the method can be based on a better system performance than a legacy protocol. All the embodiments that are implemented by the wireless device above can be implemented by the network device correspondingly.
  • FIG. 3 shows an example block diagram of a hardware platform 300 that may be a part of a network device (e.g., a base station (BS) or a transmission and reception point (TRP) ) or a wireless device (e.g., a user equipment (UE) ) .
  • the hardware platform 300 includes at least one processor 310 and a memory 305 having instructions stored thereupon. The instructions upon execution by the processor 310 configure the hardware platform 300 to perform the operations described in FIG. 1 and FIG. 2 and in the various embodiments described in this patent document.
  • the transmitter 315 transmits or sends information or data to another device.
  • a network device transmitter can send a message to a user equipment.
  • the receiver 320 receives information or data transmitted or sent by another device.
  • a user equipment can receive a message from a network device.
  • a UE, a wireless device, or a network device, as described in the present document may be implemented using the hardware platform 300.
  • FIG. 4 shows an example of a wireless communication system (e.g., a 5G or NR cellular network) that includes a base station 420 and one or more user equipment (UE) 411, 412, and 413.
  • the UEs access the BS (e.g., the network) using a communication link to the network (sometimes called uplink direction, as depicted by dashed arrows 431, 432, 433) , which then enables subsequent communication (e.g., shown in the direction from the network to the UEs, sometimes called downlink direction, shown by arrows 441, 442, 443) from the BS to the UEs.
  • a wireless communication system e.g., a 5G or NR cellular network
  • the UEs access the BS (e.g., the network) using a communication link to the network (sometimes called uplink direction, as depicted by dashed arrows 431, 432, 433) , which then enables subsequent communication (e.g., shown in the
  • the BS sends information to the UEs (sometimes called downlink direction, as depicted by arrows 441, 442, 443) , which then enables subsequent communication (e.g., shown in the direction from the UEs to the BS, sometimes called uplink direction, shown by dashed arrows 431, 432, 433) from the UEs to the BS.
  • the UE may be, for example, a smartphone, a tablet, a mobile computer, a machine to machine (M2M) device, an Internet of Things (IoT) device, and so on.
  • M2M machine to machine
  • IoT Internet of Things
  • the UEs described in the present document may be communicatively coupled to the base station 420 depicted in FIG. 4.
  • a computer-readable medium may include removable and non-removable storage devices including, but not limited to, Read Only Memory (ROM) , Random Access Memory (RAM) , compact discs (CDs) , digital versatile discs (DVD) , etc. Therefore, the computer-readable media can include a non-transitory storage media.
  • program modules may include routines, programs, objects, components, data structures, etc. that perform particular tasks or implement particular abstract data types.
  • Computer-or processor-executable instructions, associated data structures, and program modules represent examples of program code for executing steps of the methods disclosed herein. The particular sequence of such executable instructions or associated data structures represents examples of corresponding acts for implementing the functions described in such steps or processes.
  • a hardware circuit implementation can include discrete analog and/or digital components that are, for example, integrated as part of a printed circuit board.
  • the disclosed components or modules can be implemented as an Application Specific Integrated Circuit (ASIC) and/or as a Field Programmable Gate Array (FPGA) device.
  • ASIC Application Specific Integrated Circuit
  • FPGA Field Programmable Gate Array
  • DSP digital signal processor
  • the various components or sub-components within each module may be implemented in software, hardware, or firmware.
  • the connectivity between the modules and/or components within the modules may be provided using any one of the connectivity methods and media that is known in the art, including, but not limited to, communications over the Internet, wired, or wireless networks using the appropriate protocols.

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Abstract

Systems, methods, and apparatus for wireless communication are disclosed. The methods improve precoding matrix indicator (PMI) reporting accuracy and reduce reporting overhead. An example wireless communication method includes receiving, by a wireless device, a channel state information (CSI) reporting configuration signaling and a reference signal (RS) for a channel measurement. The method further includes transmitting, by the wireless device, a CSI, where the CSI is determined based on the CSI reporting configuration signaling and the RS for the channel measurement, where the CSI includes at least one of a CSI-RS resource indicator (CRI), a rank indicator (RI), a layer indicator (LI), a precoding matrix indicator (PMI), or a channel quality indicator (CQI), and where the PMI indicates a v-layer precoding matrix.

Description

LOW-COMPLEXITY CODEBOOK DESIGN TECHNICAL FIELD
This patent document is directed generally to wireless communications.
BACKGROUND
Mobile telecommunication technologies are moving the world toward an increasingly connected and networked society. In comparison with the existing wireless networks, next-generation systems and wireless communication techniques will need to support a much wider range of use-case characteristics and provide a more complex and sophisticated range of access requirements and flexibilities.
Long-Term Evolution (LTE) is a standard for wireless communication for mobile devices and data terminals developed by 3rd Generation Partnership Project (3GPP) . LTE Advanced (LTE-A) is a wireless communication standard that enhances the LTE standard. The 5th generation of wireless system, known as 5G, advances the LTE and LTE-A wireless standards and is committed to supporting higher data rates, large number of connections, ultra-low latency, high reliability, and other emerging business needs.
SUMMARY
Low-complexity codebook structures are disclosed to improve precoding matrix indicator (PMI) reporting accuracy and reduce reporting overhead. One disclosed codebook structure is based on spatial-domain (SD) bases only. Another disclosed codebook structure is based on both SD bases and frequency-domain (FD) bases.
A first example wireless communication method includes receiving, by a wireless device, a channel state information (CSI) reporting configuration signaling and a reference signal (RS) for a channel measurement. The method further includes transmitting, by the wireless device, a CSI, where the CSI is determined based on the CSI reporting configuration signaling and the RS for the channel measurement, where the CSI includes at least one of a CSI-RS resource indicator (CRI) , a rank indicator (RI) , a layer indicator (LI) , a precoding matrix indicator (PMI) , or a channel quality indicator (CQI) , and where the PMI indicates a v-layer precoding matrix.
A second example wireless communication method includes transmitting, by a network device, a channel state information (CSI) reporting configuration signaling and a reference signal (RS) for a channel measurement. The method further includes receiving, by the network device, a CSI, where the CSI is determined based on the CSI reporting configuration signaling and the RS for the channel measurement, where the CSI includes at least one of a CSI-RS resource indicator (CRI) , a rank indicator (RI) , a layer indicator (LI) , a precoding matrix indicator (PMI) , or a channel quality indicator (CQI) , and where the PMI indicates a v-layer precoding matrix.
Note that where the patent document discloses a method of transmitting an information by a first device to a second device, it will be understood that a method of receiving the information by the second device from the first device is also disclosed.
In yet another example embodiment, a device that is configured or operable to perform the above-described methods is disclosed. The device includes at least one processor configured to implement the above-described methods.
In yet another example embodiment, the above-described methods are embodied in the form of processor-executable code and stored in a non-transitory computer-readable storage medium. The code included in the computer readable storage medium when executed by a processor, causes the processor to implement the methods described in this patent document.
The above and other aspects and their implementations are described in greater detail in the drawings, the descriptions, and the claims.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is an example flowchart for transmitting a channel state information (CSI) .
FIG. 2 is an example flowchart for receiving a CSI.
FIG. 3 illustrates an example block diagram of a hardware platform that may be a part of a network device or a wireless device.
FIG. 4 illustrates example wireless communication including a Base Station (BS) and User Equipments (UEs) based on some implementations of the disclosed technology.
DETAILED DESCRIPTION
The example headings for the various sections below are used to facilitate the understanding of the disclosed subject matter and do not limit the scope of the claimed subject matter in any way. Accordingly, one or more features of one example section can be combined with one or more features of another example section. Furthermore, 5G terminology is used for the sake of clarity of explanation, but the techniques disclosed in the present document are not limited to 5G technology only and may be used in wireless systems that implemented other protocols.
I. Introduction
The present patent document describes low-complexity codebook structures that improve precoding matrix indicator (PMI) reporting accuracy and reduce reporting overhead.
In a multiple-input-multiple-output (MIMO) communication system operated in a frequency-division-duplexing (FDD) mode, a user equipment (UE) typically measures the downlink (DL) channel state information (CSI) through a DL reference signal (RS) and feeds back the CSI to a base station (BS) . The CSI can include at least one of: a CSI-RS resource indicator (CRI) , a rank indicator (RI) , a layer indicator (LI) , a precoding matrix indicator (PMI) , and a channel quality indicator (CQI) . Among these CSI quantities, PMI reflects the DL channel response and costs the highest reporting overhead. Typically, PMI reporting is based on a predefined codebook. Hence, the reporting accuracy and overhead are determined by the codebook structure. In this patent document, we propose a low-complexity codebook structure with guaranteed DL precoding performance. Specifically, the method includes the following embodiments:
‐ Embodiment 1: Codebook structure based on spatial-domain (SD) bases only;
‐ Embodiment 2: Codebook structure based on both SD bases and frequency-domain (FD) bases.
Up to release 17, the 3rd Generation Partnership Project (3GPP) protocols specify mainly two types of codebooks, namely Type-I and Type-II/enhanced Type-II (e-Type-II) codebooks for PMI reporting. In release 17, the 3GPP protocols further introduce two types of enhanced eType-II codebooks, namely eType-II codebook for coherent joint transmission (CJT) and eType-II codebook for predicted PMI, which support PMI reporting in CJT and medium/high speed scenarios, respectively. In comparison, Type-I codebook has a simple structure and costs low reporting overhead, while Type-II/eType-II codebook has a complex  structure and costs high reporting overhead. In practical implementations, Type-I cannot meet the demand of high-resolution PMI feedback, and hence shows poor performance. Meanwhile, Type-II/eType-II codebook suffers from unacceptable high reporting overhead and high implementation complexity. Therefore, a usable codebook with acceptable performance and reporting overhead is urgently needed. In this patent document, we propose a low-complexity codebook based on the Type-II/eType-II codebook framework. The proposed new codebook enables low-complexity PMI calculation and low-overhead PMI reporting, and meanwhile guarantees the precoding performance.
First, we provide explanations of some terminologies to be used in the patent document.
In this patent document,
“UE” can be equivalent to wireless communication device;
“BS” can be equivalent to gNB (the next Generation Node B) , wireless network device, or TRP (Transmission and Reception Point) ;
“antenna port” can be equivalent to “BS antenna port” , or “CSI-RS (Channel State Information Reference Signal) antenna port” ;
“higher layer parameter” can be equivalent to “RRC (Radio Resource Control) parameter” , “Physical Downlink Control Channel (PDCCH) ” , or “Downlink control information (DCI) ” ;
“SD basis” can be equivalent to vl, m orThe quantities vl, m andcorresponding to (l, m) are defined in clause 5.2.2.2.1 of TS 38.214 as


where N1 N2 are defined in clause 5.2.2.2.1 of TS 38.214, the number of antenna ports P=2N1N2, and O1 O2 are oversampling factors defined in clause 5.2.2.2.1 of TS 38.214.
The FD (Frequency Domain) basis corresponding toand l is defined in clause 5.2.2.2.5 of TS 38.214 as
whereN3 is the number of total precoding matrices, Mv is the number of selected FD bases, and l is the layer index or layer group index;
“coefficient” can be equivalent to “combination coefficient” ;
“amplitude” can be equivalent to “amplitude coefficient” , or “coefficient amplitude” ;
“phase” can be equivalent to “phase coefficient” , or “coefficient phase” .
The general procedure of CSI reporting is as follows:
UE receives CSI reporting configuration signaling and RS for channel measurement from BS;
UE determines CSI based on the CSI reporting configuration signaling and RS for channel measurement, where the CSI contains at least of CRI, RI, LI, PMI, and CQI, and the PMI indicates a v-layer precoding matrix;
UE sends the CSI to BS.
II. Embodiment 1
Embodiment 1 discloses a codebook structure based on SD bases only.
Corresponding to each layer or layer group, the PMI can include a number of SD bases (or an indicator of a number of SD bases) , a number of combination coefficients (or an indicator of a number of combination coefficients) , and a polarization coefficient (or an indicator of a polarization coefficient) .
Each layer group can include X or less layers. The number of layer groups is
X can be a configurable higher layer parameter.
X can be a predefined value, e.g., 1, 2, or 4.
The SD bases can be layer common/specific or layer group common/specific. Within each layer group, the SD bases are common across different layers.
For each layer or layer group, the number of SD bases can be L.
L can be a configurable higher layer parameter. Candidate value of L can be {2, 4, 6, 8} .
The ith SD basis among the L SD bases can be denoted aswherecan be expressed as

are indicated by a combinatorial number included in the PMI, {q1, q2} , 0≤q1≤O1-1, 0≤q2≤O1-1 are a pair of integers included in the PMI.
The polarization coefficient can be layer common/specific or layer group common/specific. Within each layer group, the polarization coefficient is common across different layers.
The polarization coefficient can be subband specific/common.
The polarization coefficient θl corresponding to lth layer or layer group can be expressed as
where Qθ can be 1, 2, 3, or 4.
For each layer or layer group, the PMI includes L combination coefficients. Within each layer group, the L combination coefficients are common across different layers. The combination coefficient corresponding to the lth layer or layer group and the ith SD basis al, i can be expressed as
whereis the wideband amplitude, is the subband amplitude, is the phase, andwhere can be 1, 2, 3, or 4.
The greatest combination coefficient among the L combination coefficients can be indicated by an integer belonging to {0, 1, . . ., L-1} . This integer is included in the PMI and reported to BS. The greatest combination coefficient is not reported.
The wideband amplitudeis subband common.
The subband amplitudeis subband specific. can be fixed as 1, thencan be not reported.
The amplitudecan be fixed as 1, thenandcan be not reported.
Whenis fixed as 1, the combination coefficient equaling to 1 among the L combination coefficients can be indicated by an integer belonging to {0, 1, . . ., L-1} . This  integer is included in the PMI and reported to BS. The combination coefficient equaling to 1 is not reported.
The phasecan be subband specific/common.
The phasecan be fixed as ej2π=1, then the phasecan be not reported.
The precoding matrix indicated by the PMI, or the codebook structure, can be expressed as
where Wl is the precoding matrix corresponding to the lth layer or layer group.
The precoding matrix to the l-th layer or l-th layer group can be expressed in one of the following formulas:




III. Embodiment 2
Embodiment 2 discloses a codebook structure based on both SD bases and FD bases.
Corresponding to each layer or layer group, the PMI can include a number of SD bases (or an indicator of a number of SD bases) , a number of FD bases (or an indicator of a number of FD bases) , a number of combination coefficients (or an indicator of a number of combination coefficients) , and a polarization coefficient (or an indicator of a polarization coefficient) .
Each layer group can include X or less layers. The number of layer groups is
X can be a configurable higher layer parameter.
X can be a predefined value, e.g., 1, 2, or 4.
The SD bases can be layer common/specific or layer group common/specific. Within each layer group, the SD bases are common across different layers.
For each layer or layer group, the number of SD bases can be L.
L can be a configurable higher layer parameter. Candidate value of L can be {2, 4, 6, 8}.
The ith SD basis among the L SD bases can be denoted aswherecan be expressed as

are indicated by a combinatorial number included in the PMI, {q1, q2} , 0≤q1≤O1-1, 0≤q2≤O1-1 are a pair of integers included in the PMI.
The FD bases can be layer specific/common, or layer group specific/common. Within each layer group, the FD bases are common across different layers.
The polarization coefficient can be layer common/specific or layer group common/specific. Within each layer group, the polarization coefficient is common across different layers.
The polarization coefficient can be subband specific/common.
The polarization coefficient θl corresponding to lth layer or layer group can be expressed as
where Qθ can be 1, 2, 3, or 4.
For each layer or layer group, the PMI includes L·Mv combination coefficients. Within each layer group, the L·Mv combination coefficients are common across different layers. The combination coefficient corresponding to the lth layer or layer group, the ith SD basis, and the fth FD basis and the ith, al, i, f, can be expressed as
where pl, i, f is the amplitude, andis the phase, wherecan be 1, 2, 3, or 4.
The greatest combination coefficient can be indicated by an integer belonging to {0, 1, . . ., L-1} and an integer belonging to {0, 1, . . ., Mv-1} . These two integers are included in the PMI and reported to BS. The greatest combination coefficient can be not reported.
The amplitude pl, i, f can be fixed as 1, then pl, i, f can be not reported.
If the amplitude pl, i, f is fixed as 1 and not reported, the combination coefficient equaling to 1 among the L·Mv combination coefficients can be indicated by an integer belonging to {0, 1, . . ., L-1} and an integer belonging to {0, 1, . . ., Mv-1} , these two integers are included in the PMI and reported to BS.
The phasecan be fixed as ej2π=1, thencan be not reported.
The precoding matrix indicated by the PMI or the codebook structure, corresponding to index t (t = {0, 1, 2, . . ., N3 -1} ) , can be expressed as
whereis the precoding matrix corresponding to index t and the lth layer or layer group.
can be expressed in one of the following formulas:




In this patent document, we propose a low-complexity codebook design for PMI reporting. The new codebook structure is based on the basic framework of Type-II/eType-II codebook. Enhanced designs are proposed to reduce the PMI reporting overhead with guaranteed precoding performance, especially when the number of antenna ports is increased to 128. Embodiment 1 gives a codebook structure based on SD bases only, while embodiment 2 gives a codebook structure based on both SD bases and FD bases.
FIG. 1 is an example flowchart for transmitting a channel state information (CSI) . Operation 102 includes receiving, by a wireless device, a channel state information (CSI) reporting configuration signaling and a reference signal (RS) for a channel measurement. Operation 104 includes transmitting, by the wireless device, a CSI, where the CSI is determined based on the CSI reporting configuration signaling and the RS for the channel measurement, where the CSI includes at least one of a CSI-RS resource indicator (CRI) , a rank indicator (RI) , a layer indicator (LI) , a precoding matrix indicator (PMI) , or a channel quality indicator (CQI) , and where the PMI indicates a v-layer precoding matrix. In some embodiments, v is a number greater than 1, and the method is implemented for a multi-layer scheme. In some embodiments, the method can be implemented according to Embodiment 1 and Embodiment 2. In some embodiments, performing further steps of the method can be based on a better system performance than a legacy protocol.
In some embodiments, the PMI includes at least one of the following: a number of spatial domain (SD) bases corresponding to each layer or layer group; an indicator of the number of SD bases corresponding to each layer or layer group; a number of combination coefficients corresponding to each layer or layer group; an indicator of the number of combination coefficients corresponding to each layer or layer group; a number of polarization coefficients corresponding to each layer or layer group; or an indicator of the number of polarization coefficients corresponding to each layer or layer group.
In some embodiments, each layer group includes X or less layers, where a number of layer groups isand where X is a configurable higher layer parameter or a predefined value including 1, 2, or 4.
In some embodiments, the SD bases are layer-common, layer-specific, layer-group-common, or layer-group-specific, and within each layer group, the SD bases are common across different layers.
In some embodiments, for each layer or layer group, the number of SD bases is L, where L is a configurable higher layer parameter including 2, 4, 6, or 8.
In some embodiments, the polarization coefficients are layer-common, layer-specific, layer-group-common, layer-group-specific, subband-common, or subband-specific, and within each layer group, the polarization coefficients are common across different layers.
In some embodiments, a polarization coefficient θl corresponding to an lth layer or layer group iswhere Qθ is 1, 2, 3, or 4.
In some embodiments, for each layer or layer group, the PMI includes L combination coefficients, and within each layer group, the L combination coefficients are common across different layers.
In some embodiments, a greatest combination coefficient among L combination coefficients is indicated by a first integer belonging to {0, 1, . . ., L-1} , where the first integer is reported in the PMI, and where the greatest combination coefficient is not reported.
In some embodiments, a combination coefficient al, i corresponding to an lth layer or layer group and an ith SD basis is determined by at least one oforwhereinis a wideband amplitude, is a subband amplitude, andis a phase, and whereinis 1, 2, 3, or 4.
In some embodiments, the wideband amplitudeis subband-common, the subband amplitudeis subband-specific, and the phaseis subband-common or subband-specific, where at least one of the following applies: the combination coefficient al, i is determined byandasthe combination coefficient al, i is determined byasthecombination coefficient al, i is determined byasacombination coefficient that is equal to 1 among L combination coefficients is indicated by a second integer belonging to {0, 1, . . ., L-1} , the second integer is reported in the PMI, and the combination coefficient that is equal to 1 is not reported; the combination coefficient al, i is determined byandas or the combination coefficient al, i is determined byas
In some embodiments, a precoding matrix indicated by the PMI or a codebook structure iswhere Wl is a precoding matrix corresponding to an lth layer or layer group.
In some embodiments, the precoding matrix corresponding to the l-th layer or layer group is determined by at least one of the following: spatial domain (SD) bases corresponding to the l-th layer or layer group; combination coefficients corresponding to the l-th layer or layer group; or polarization coefficients corresponding to the l-th layer or layer group.
In some embodiments, the precoding matrix corresponding to the l-th layer or layer group is at least one of the following:

wherean ith spatial domain (SD) basis corresponding to the l-th layer or layer group.
In some embodiments, the PMI includes at least one of the following: a number of spatial domain (SD) bases corresponding to each layer or layer group; an indicator of the number of SD bases corresponding to each layer or layer group; a number of frequency domain (FD) bases corresponding to each layer or layer group; an indicator of the number of FD bases corresponding to each layer or layer group; a number of combination coefficients corresponding to each layer or layer group; an indicator of the number of combination coefficients corresponding to each layer or layer group; a number of polarization coefficients corresponding to each layer or layer group; or an indicator of the number of polarization coefficients corresponding to each layer or layer group.
In some embodiments, each layer group includes X or less layers, where a number of layer groups isand where X is a configurable higher layer parameter or a predefined value including 1, 2, or 4.
In some embodiments, the SD bases and the FD bases are layer-common, layer-specific, layer-group-common, or layer-group-specific, and within each layer group, the SD bases and the FD bases are common across different layers.
In some embodiments, for each layer or layer group, the number of SD bases is L, where L is a configurable higher layer parameter including 2, 4, 6, or 8.
In some embodiments, the polarization coefficients are layer-common, layer-specific, layer-group-common, layer-group-specific, subband-common, or subband-specific, and within each layer group, the polarization coefficients are common across different layers.
In some embodiments, a polarization coefficient θl corresponding to an lth layer or layer group iswhere Qθ is 1, 2, 3, or 4.
In some embodiments, for each layer or layer group, the PMI includes L·Mv combination coefficients, where Mv is a number of FD bases, and where within each layer group, the L·Mv combination coefficients are common across different layers.
In some embodiments, a greatest combination coefficient is indicated by a first integer belonging to {0, 1, . . ., L-1} and a second integer belonging to {0, 1, . . ., Mv-1} , where the first and second integers are reported in the PMI, and where the greatest combination coefficient is not reported.
In some embodiments, a combination coefficient al, i, f corresponding to an lth layer or layer group, an ith SD basis, and an fth FD basis is determined by at least one of pl, i, forwherein pl, i, f is an amplitude andis a phase, and whereinis 1, 2, 3, or 4.
In some embodiments, at least one of the following applies: the combination coefficient al,i, f is determined by pl, i, f andasthe combination coefficient al, i, f is determined byasthe combination coefficient al, i, f is determined byas acombination coefficient that is equal to 1 among L·Mv combination coefficients is indicated by a third integer belonging to {0, 1, . . ., L-1} and a fourth integer belonging to {0, 1, . . ., Mv-1} , and the third and fourth integers are reported in the PMI; or the combination coefficient al, i, f is determined by pl, i, f as al, i, f=pl, i, f.
In some embodiments, a precoding matrix indicated by the PMI or a codebook structure corresponds to an index t (t = {0, 1, 2, . . ., N3 -1} ) and is where N3 is an integer determined by the CSI reporting configuration signaling, and whereis a precoding matrix corresponding to the index t and an lth layer or layer group.
In some embodiments, is determined by at least one of the following: spatial domain (SD) bases corresponding to the lth layer or layer group; frequency domain (FD) bases corresponding to the lth layer or layer group; combination coefficients corresponding to the lth layer or layer group; or polarization coefficients corresponding to the lth layer or layer group.
In some embodiments, is at least one of the following:

whereis an ith spatial domain (SD) basis corresponding to the l-th layer or layer group.
FIG. 2 is an example flowchart for receiving a channel state information (CSI) . Operation 202 includes transmitting, by a network device, a channel state information (CSI) reporting configuration signaling and a reference signal (RS) for a channel measurement. Operation 204 includes receiving, by the network device, a CSI, where the CSI is determined based on the CSI reporting configuration signaling and the RS for the channel measurement, where the CSI includes at least one of a CSI-RS resource indicator (CRI) , a rank indicator (RI) , a layer indicator (LI) , a precoding matrix indicator (PMI) , or a channel quality indicator (CQI) , and where the PMI indicates a v-layer precoding matrix. In some embodiments, v is a number greater than 1, and the method is implemented for a multi-layer scheme. In some embodiments, the method can be implemented according to Embodiment 1 and Embodiment 2. In some embodiments, performing further steps of the method can be based on a better system performance than a legacy protocol. All the embodiments that are implemented by the wireless device above can be implemented by the network device correspondingly.
FIG. 3 shows an example block diagram of a hardware platform 300 that may be a part of a network device (e.g., a base station (BS) or a transmission and reception point (TRP) ) or a wireless device (e.g., a user equipment (UE) ) . The hardware platform 300 includes at least one processor 310 and a memory 305 having instructions stored thereupon. The instructions upon execution by the processor 310 configure the hardware platform 300 to perform the operations described in FIG. 1 and FIG. 2 and in the various embodiments described in this patent document. The transmitter 315 transmits or sends information or data to another device. For example, a network device transmitter can send a message to a user equipment. The receiver 320 receives information or data transmitted or sent by another device. For example, a user equipment can receive a message from a network device. For example, a UE, a wireless device,  or a network device, as described in the present document, may be implemented using the hardware platform 300.
The implementations as discussed above will apply to a wireless communication. FIG. 4 shows an example of a wireless communication system (e.g., a 5G or NR cellular network) that includes a base station 420 and one or more user equipment (UE) 411, 412, and 413. In some embodiments, the UEs access the BS (e.g., the network) using a communication link to the network (sometimes called uplink direction, as depicted by dashed arrows 431, 432, 433) , which then enables subsequent communication (e.g., shown in the direction from the network to the UEs, sometimes called downlink direction, shown by arrows 441, 442, 443) from the BS to the UEs. In some embodiments, the BS sends information to the UEs (sometimes called downlink direction, as depicted by arrows 441, 442, 443) , which then enables subsequent communication (e.g., shown in the direction from the UEs to the BS, sometimes called uplink direction, shown by dashed arrows 431, 432, 433) from the UEs to the BS. The UE may be, for example, a smartphone, a tablet, a mobile computer, a machine to machine (M2M) device, an Internet of Things (IoT) device, and so on. The UEs described in the present document may be communicatively coupled to the base station 420 depicted in FIG. 4.
It will be appreciated by one of skill in the art that the present patent document discloses low-complexity codebook structures based on spatial-domain (SD) bases only or based on both SD bases and frequency-domain (FD) bases. The patent document improves precoding matrix indicator (PMI) reporting accuracy and reduces reporting overhead.
Some of the embodiments described herein are described in the general context of methods or processes, which may be implemented in one embodiment by a computer program product, embodied in a computer-readable medium, including computer-executable instructions, such as program code, executed by computers in networked environments. A computer-readable medium may include removable and non-removable storage devices including, but not limited to, Read Only Memory (ROM) , Random Access Memory (RAM) , compact discs (CDs) , digital versatile discs (DVD) , etc. Therefore, the computer-readable media can include a non-transitory storage media. Generally, program modules may include routines, programs, objects, components, data structures, etc. that perform particular tasks or implement particular abstract data types. Computer-or processor-executable instructions, associated data structures, and program modules represent examples of program code for executing steps of the methods  disclosed herein. The particular sequence of such executable instructions or associated data structures represents examples of corresponding acts for implementing the functions described in such steps or processes.
Some of the disclosed embodiments can be implemented as devices or modules using hardware circuits, software, or combinations thereof. For example, a hardware circuit implementation can include discrete analog and/or digital components that are, for example, integrated as part of a printed circuit board. Alternatively, or additionally, the disclosed components or modules can be implemented as an Application Specific Integrated Circuit (ASIC) and/or as a Field Programmable Gate Array (FPGA) device. Some implementations may additionally or alternatively include a digital signal processor (DSP) that is a specialized microprocessor with an architecture optimized for the operational needs of digital signal processing associated with the disclosed functionalities of this application. Similarly, the various components or sub-components within each module may be implemented in software, hardware, or firmware. The connectivity between the modules and/or components within the modules may be provided using any one of the connectivity methods and media that is known in the art, including, but not limited to, communications over the Internet, wired, or wireless networks using the appropriate protocols.
While this document contains many specifics, these should not be construed as limitations on the scope of an invention that is claimed or of what may be claimed, but rather as descriptions of features specific to particular embodiments. Certain features that are described in this document in the context of separate embodiments can also be implemented in combination in a single embodiment. Conversely, various features that are described in the context of a single embodiment can also be implemented in multiple embodiments separately or in any suitable sub-combination. Moreover, although features may be described above as acting in certain combinations and even initially claimed as such, one or more features from a claimed combination can in some cases be excised from the combination, and the claimed combination may be directed to a sub-combination or a variation of a sub-combination. Similarly, while operations are depicted in the drawings in a particular order, this should not be understood as requiring that such operations be performed in the particular order shown or in sequential order, or that all illustrated operations be performed, to achieve desirable results.
Only a few implementations and examples are described, and other implementations, enhancements and variations can be made based on what is described and illustrated in this patent document.

Claims (30)

  1. A method of wireless communication, comprising:
    receiving, by a wireless device, a channel state information (CSI) reporting configuration signaling and a reference signal (RS) for a channel measurement; and
    transmitting, by the wireless device, a CSI, wherein the CSI is determined based on the CSI reporting configuration signaling and the RS for the channel measurement, wherein the CSI comprises at least one of a CSI-RS resource indicator (CRI) , a rank indicator (RI) , a layer indicator (LI) , a precoding matrix indicator (PMI) , or a channel quality indicator (CQI) , and wherein the PMI indicates a v-layer precoding matrix.
  2. The method of claim 1, wherein the PMI comprises at least one of the following:
    a number of spatial domain (SD) bases corresponding to each layer or layer group;
    an indicator of the number of SD bases corresponding to each layer or layer group;
    a number of combination coefficients corresponding to each layer or layer group;
    an indicator of the number of combination coefficients corresponding to each layer or layer group;
    a number of polarization coefficients corresponding to each layer or layer group; or
    an indicator of the number of polarization coefficients corresponding to each layer or layer group.
  3. The method of claim 2, wherein each layer group comprises X or less layers, wherein a number of layer groups isand wherein X is a configurable higher layer parameter or a predefined value comprising 1, 2, or 4.
  4. The method of claim 2 or 3, wherein the SD bases are layer-common, layer-specific, layer-group-common, or layer-group-specific, and wherein within each layer group, the SD bases are common across different layers.
  5. The method of any of claims 2-4, wherein for each layer or layer group, the number of SD  bases is L, and wherein L is a configurable higher layer parameter comprising 2, 4, 6, or 8.
  6. The method of any of claims 2-5, wherein the polarization coefficients are layer-common, layer-specific, layer-group-common, layer-group-specific, subband-common, or subband-specific, and wherein within each layer group, the polarization coefficients are common across different layers.
  7. The method of any of claims 2-6, wherein a polarization coefficient θl corresponding to an lth layer or layer group isand wherein Qθ is 1, 2, 3, or 4.
  8. The method of any of claims 2-7, wherein for each layer or layer group, the PMI comprises L combination coefficients, and wherein within each layer group, the L combination coefficients are common across different layers.
  9. The method of any of claims 2-8, wherein a greatest combination coefficient among L combination coefficients is indicated by a first integer belonging to {0, 1, ..., L-1} , wherein the first integer is reported in the PMI, and wherein the greatest combination coefficient is not reported.
  10. The method of any of claims 2-9, wherein a combination coefficient al, i corresponding to an lth layer or layer group and an ith SD basis is determined by at least one oforwhereinis a wideband amplitude, is a subband amplitude, and is a phase, and whereinis 1, 2, 3, or 4.
  11. The method of claim 10, wherein the wideband amplitudeis subband-common, the subband amplitudeis subband-specific, and the phaseis subband-common or subband-specific, and wherein at least one of the following applies:
    the combination coefficient al, i is determined byandas
    the combination coefficient al, i is determined byas
    the combination coefficient al, i is determined byasa combination  coefficient that is equal to 1 among L combination coefficients is indicated by a second integer belonging to {0, 1, ..., L-1} , the second integer is reported in the PMI, and the combination coefficient that is equal to 1 is not reported;
    the combination coefficient al, i is determined byandasor
    the combination coefficient al, i is determined byas
  12. The method of any of claims 1-11, wherein a precoding matrix indicated by the PMI or a codebook structure isand wherein Wl is a precoding matrix corresponding to an lth layer or layer group.
  13. The method of claim 12, wherein the precoding matrix corresponding to the l-th layer or layer group is determined by at least one of the following:
    spatial domain (SD) bases corresponding to the l-th layer or layer group;
    combination coefficients corresponding to the l-th layer or layer group; or
    polarization coefficients corresponding to the l-th layer or layer group.
  14. The method of claim 12 or 13, wherein the precoding matrix corresponding to the l-th layer or layer group is at least one of the following:
    or
    and whereinis an ith spatial domain (SD) basis corresponding to the l-th layer or layer group.
  15. The method of claim 1, wherein the PMI comprises at least one of the following:
    a number of spatial domain (SD) bases corresponding to each layer or layer group;
    an indicator of the number of SD bases corresponding to each layer or layer group;
    a number of frequency domain (FD) bases corresponding to each layer or layer group;
    an indicator of the number of FD bases corresponding to each layer or layer group;
    a number of combination coefficients corresponding to each layer or layer group;
    an indicator of the number of combination coefficients corresponding to each layer or layer group;
    a number of polarization coefficients corresponding to each layer or layer group; or
    an indicator of the number of polarization coefficients corresponding to each layer or layer group.
  16. The method of claim 15, wherein each layer group comprises X or less layers, wherein a number of layer groups isand wherein X is a configurable higher layer parameter or a predefined value comprising 1, 2, or 4.
  17. The method of claim 15 or 16, wherein the SD bases and the FD bases are layer-common, layer-specific, layer-group-common, or layer-group-specific, and wherein within each layer group, the SD bases and the FD bases are common across different layers.
  18. The method of any of claims 15-17, wherein for each layer or layer group, the number of SD bases is L, and wherein L is a configurable higher layer parameter comprising 2, 4, 6, or 8.
  19. The method of any of claims 15-18, wherein the polarization coefficients are layer-common, layer-specific, layer-group-common, layer-group-specific, subband-common, or subband-specific, and wherein within each layer group, the polarization coefficients are common across different layers.
  20. The method of any of claims 15-19, wherein a polarization coefficient θl corresponding to an lth layer or layer group isand wherein Qθ is 1, 2, 3, or 4.
  21. The method of any of claims 15-20, wherein for each layer or layer group, the PMI comprises L·Mv combination coefficients, wherein Mv is a number of FD bases, and wherein within each layer group, the L·Mv combination coefficients are common across different layers.
  22. The method of any of claims 15-21, wherein a greatest combination coefficient is indicated by a first integer belonging to {0, 1, ..., L-1} and a second integer belonging to {0, 1, ..., Mv-1} , wherein the first and second integers are reported in the PMI, and wherein the greatest combination coefficient is not reported.
  23. The method of any of claims 15-22, wherein a combination coefficient al, i, f corresponding to an lth layer or layer group, an ith SD basis, and an fth FD basis is determined by at least one of pl, i, f orwherein pl, i, f is an amplitude andis a phase, and whereinis 1, 2, 3, or 4.
  24. The method of claim 23, wherein at least one of the following applies:
    the combination coefficient al, i, f is determined by pl, i, f andas
    the combination coefficient al, i, f is determined byas
    the combination coefficient al, i, f is determined byasa combination coefficient that is equal to 1 among L·Mv combination coefficients is indicated by a third integer belonging to {0, 1, ..., L-1} and a fourth integer belonging to {0, 1, ..., Mv-1} , and the third and fourth integers are reported in the PMI; or
    the combination coefficient al, i, f is determined by pl, i, f as al, i, f=pl, i, f.
  25. The method of any of claims 15-24, wherein a precoding matrix indicated by the PMI or a codebook structure corresponds to an index t (t = {0, 1, 2, ..., N3 -1} ) and is wherein N3 is an integer determined by the CSI reporting configuration signaling, and whereinis a precoding matrix corresponding to the index t and an lth layer or layer group.
  26. The method of claim 25, whereinis determined by at least one of the following:
    spatial domain (SD) bases corresponding to the lth layer or layer group;
    frequency domain (FD) bases corresponding to the lth layer or layer group;
    combination coefficients corresponding to the lth layer or layer group; or
    polarization coefficients corresponding to the lth layer or layer group.
  27. The method of claim 25 or 26, whereinis at least one of the following:
    or
    and whereinis an ith spatial domain (SD) basis corresponding to the l-th layer or layer group.
  28. A method of wireless communication, comprising:
    transmitting, by a network device, a channel state information (CSI) reporting configuration signaling and a reference signal (RS) for a channel measurement; and
    receiving, by the network device, a CSI, wherein the CSI is determined based on the CSI reporting configuration signaling and the RS for the channel measurement, wherein the CSI comprises at least one of a CSI-RS resource indicator (CRI) , a rank indicator (RI) , a layer indicator (LI) , a precoding matrix indicator (PMI) , or a channel quality indicator (CQI) , and wherein the PMI indicates a v-layer precoding matrix.
  29. An apparatus for wireless communication, comprising a processor, wherein the processor is configured to implement a method recited in any one or more of claims 1 to 28.
  30. A computer readable program storage medium having code stored thereon, the code, when executed by a processor, causing the processor to implement a method recited in any one or more of claims 1 to 28.
PCT/CN2024/074097 2024-01-25 2024-01-25 Low-complexity codebook design WO2024099480A1 (en)

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Citations (4)

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US20230061722A1 (en) * 2020-02-07 2023-03-02 Qualcomm Incorporated Dynamic interference measurement for multiple-trp csi
US20230254718A1 (en) * 2022-02-04 2023-08-10 Samsung Electronics Co., Ltd. Method and apparatus for channel quality reporting
WO2023199293A1 (en) * 2022-04-15 2023-10-19 Lenovo (Singapore) Pte. Ltd. Techniques for joint channel state information training and precoder matrix indicator feedback for artificial intelligence-enabled networks
US20230344488A1 (en) * 2022-03-21 2023-10-26 Mediatek Singapore Pte. Ltd. Method for full power multiple transmission reception point communication system

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20230061722A1 (en) * 2020-02-07 2023-03-02 Qualcomm Incorporated Dynamic interference measurement for multiple-trp csi
US20230254718A1 (en) * 2022-02-04 2023-08-10 Samsung Electronics Co., Ltd. Method and apparatus for channel quality reporting
US20230344488A1 (en) * 2022-03-21 2023-10-26 Mediatek Singapore Pte. Ltd. Method for full power multiple transmission reception point communication system
WO2023199293A1 (en) * 2022-04-15 2023-10-19 Lenovo (Singapore) Pte. Ltd. Techniques for joint channel state information training and precoder matrix indicator feedback for artificial intelligence-enabled networks

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