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
  • H04B7/0486—Selection of precoding matrices or codebooks, e.g. using matrices antenna weighting taking channel rank 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
  • H04B7/04—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas
  • H04B7/0413—MIMO systems
  • H04B7/0452—Multi-user MIMO systems
• • 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
• • 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
  • H04B7/04—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
• • 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
  • H04B7/06—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the transmitting station
  • H04B7/0613—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the transmitting station using simultaneous transmission
  • H04B7/0615—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the transmitting station using simultaneous transmission of weighted versions of same signal
  • H04B7/0619—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the transmitting station using simultaneous transmission of weighted versions of same signal using feedback from receiving side
  • H04B7/0621—Feedback content
  • H04B7/0626—Channel coefficients, e.g. channel state information [CSI]
• • 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
  • H04B7/06—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the transmitting station
  • H04B7/0613—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the transmitting station using simultaneous transmission
  • H04B7/0615—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the transmitting station using simultaneous transmission of weighted versions of same signal
  • H04B7/0619—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the transmitting station using simultaneous transmission of weighted versions of same signal using feedback from receiving side
  • H04B7/0621—Feedback content
  • H04B7/0632—Channel quality parameters, e.g. channel quality indicator [CQI]
• • 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
  • H04B7/06—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the transmitting station
  • H04B7/0613—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the transmitting station using simultaneous transmission
  • H04B7/0615—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the transmitting station using simultaneous transmission of weighted versions of same signal
  • H04B7/0619—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the transmitting station using simultaneous transmission of weighted versions of same signal using feedback from receiving side
  • H04B7/0621—Feedback content
  • H04B7/0634—Antenna weights or vector/matrix coefficients
• • 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
  • H04B7/06—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the transmitting station
  • H04B7/0613—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the transmitting station using simultaneous transmission
  • H04B7/0615—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the transmitting station using simultaneous transmission of weighted versions of same signal
  • H04B7/0619—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the transmitting station using simultaneous transmission of weighted versions of same signal using feedback from receiving side
  • H04B7/0636—Feedback format
  • H04B7/0639—Using selective indices, e.g. of a codebook, e.g. pre-distortion matrix index [PMI] or for beam selection
• • 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
  • H04B7/06—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the transmitting station
  • H04B7/0697—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the transmitting station using spatial multiplexing

Definitions

• This invention relates generally to wireless communication and, more specifically, relates to using many antennas in wireless communication.
• MIMO Multiple-antenna
• LTE and Wi-Fi wireless broadband standards like LTE and Wi-Fi.
• the price to pay is increased complexity of the hardware (e.g., the number of RF amplifier frontends) and the complexity and energy consumption of the signal processing at both ends.
• Massive MIMO uses a very large number of service antennas (e.g., hundreds or thousands) that are operated fully coherently and adaptively. Extra antennas help by focusing the transmission and reception of signal energy into ever-smaller regions of space. This brings improvements in throughput and energy efficiency, in particular when combined with simultaneous scheduling of a large number of user equipment (e.g., tens or hundreds).
• a method comprises: determining a precoder for a given layer and for a user equipment, wherein the precoder comprises a three-part product codebook structure, wherein the determining uses channel state information from the user equipment for the three-part product codebook structure, and wherein the channel state information corresponds to a plurality of antenna elements in at least a two-dimensional array of cross-polarized antenna elements; applying the determined precoder to information for the layer to be transmitted to the user equipment; and transmitting the precoded information for the layer to the user equipment using the plurality of antenna elements in the at least two-dimensional array of cross-polarized antenna elements.
• An additional exemplary embodiment includes a computer program, comprising code for performing the method of the previous paragraph, when the computer program is run on a processor.
• a further exemplary embodiment is an apparatus comprising: means for determining a precoder for a given layer and for a user equipment, wherein the precoder comprises a three-part product codebook structure, wherein the determining uses channel state information from the user equipment for the three-part product codebook structure, and wherein the channel state information corresponds to a plurality of antenna elements in at least a two-dimensional array of cross-polarized antenna elements; means for applying the determined precoder to information for the layer to be transmitted to the user equipment; and means for transmitting the precoded information for the layer to the user equipment using the plurality of antenna elements in the at least two-dimensional array of cross-polarized antenna elements.
• An exemplary apparatus includes one or more processors and one or more memories including computer program code.
• the one or more memories and the computer program code are configured to, with the one or more processors, cause the apparatus to perform at least the following: determining a precoder for a given layer and for a user equipment, wherein the precoder comprises a three-part product codebook structure, wherein the determining uses channel state information from the user equipment for the three-part product codebook structure, and wherein the channel state information corresponds to a plurality of antenna elements in at least a two-dimensional array of cross-polarized antenna elements; applying the determined precoder to information for the layer to be transmitted to the user equipment; and transmitting the precoded information for the layer to the user equipment using the plurality of antenna elements in the at least two-dimensional array of cross-polarized antenna elements.
• An exemplary computer program product includes a computer-readable storage medium bearing computer program code embodied therein for use with a computer.
• the computer program code includes: code for determining a precoder for a given layer and for a user equipment, wherein the precoder comprises a three-part product codebook structure, wherein the determining uses channel state information from the user equipment for the three-part product codebook structure, and wherein the channel state information corresponds to a plurality of antenna elements in at least a two-dimensional array of cross-polarized antenna elements; code for applying the determined precoder to information for the layer to be transmitted to the user equipment; and code for transmitting the precoded information for the layer to the user equipment using the plurality of antenna elements in the at least
• a method comprises: receiving at a user equipment reference signal information for a layer that has been transmitted from a base station, the reference signal information transmitted using a plurality of antenna elements in at least a two-dimensional array of cross-polarized antenna elements; determining, at the user equipment and using the reference signal information, channel state information corresponding to each part of a three-part product codebook structure for the layer; reporting by the user equipment the determined channel state information corresponding to each part of the three-part product codebook structure to the base station; and receiving at the user equipment previously precoded information for the layer transmitted from the base station using the plurality of antenna elements, where the previously precoded information is based on the reported channel state information.
• An additional exemplary embodiment includes a computer program, comprising code for performing the method of the previous paragraph, when the computer program is run on a processor.
• An additional exemplary embodiment is an apparatus comprising: means for receiving at a user equipment reference signal information for a layer that has been transmitted from a base station, the reference signal information transmitted using a plurality of antenna elements in at least a two-dimensional array of cross-polarized antenna elements; means for determining, at the user equipment and using the reference signal information, channel state information corresponding to each part of a three-part product codebook structure for the layer; means for reporting by the user equipment the determined channel state information corresponding to each part of the three-part product codebook structure to the base station; and means for receiving at the user equipment previously precoded information for the layer transmitted from the base station using the plurality of antenna elements, where the previously precoded information is based on the reported channel state information.
• An exemplary apparatus includes one or more processors and one or more memories including computer program code.
• the one or more memories and the computer program code are configured to, with the one or more processors, cause the apparatus to perform at least the following: receiving at a user equipment reference signal information for a layer that has been transmitted from a base station, the reference signal information transmitted using a plurality of antenna elements in at least a two-dimensional array of cross-polarized antenna elements; determining, at the user equipment and using the reference signal information, channel state information corresponding to each part of a three-part product codebook structure for the layer; reporting by the user equipment the determined channel state information corresponding to each part of the three-part product codebook structure to the base station; and receiving at the user equipment previously precoded information for the layer transmitted from the base station using the plurality of antenna elements, where the previously precoded information is based on the reported channel state information.
• An exemplary computer program product includes a computer-readable storage medium bearing computer program code embodied therein for use with a computer.
• the computer program code includes: code for determining, at the user equipment and using the reference signal information, channel state information corresponding to each part of a three-part product codebook structure for the layer; code for reporting by the user equipment the determined channel state information corresponding to each part of the three-part product codebook structure to the base station; and code for receiving at the user equipment previously precoded information for the layer transmitted from the base station using the plurality of antenna elements, where the previously precoded information is based on the reported channel state information.
• FIG. 1 is a block diagram of an exemplary system in which the exemplary embodiments may be practiced
• FIG. 2 is a chart of sector Spectral Efficiency (SE) versus various Full Dimension (FD) MIMO methods for the 3D Urban Micro (3D UMi) environment with 10 0.5 ⁇ elevation ports with 2 azimuth cross polarization (Xpols);
• SE sector Spectral Efficiency
• FD Full Dimension
• FIG. 3 is a 3D planar antenna structure where each column is a cross-polarized array
• FIG. 4 is a logic flow diagram performed by a base station for combination of scalar quantization and codebooks for precoder design for massive MIMO, and illustrates the operation of an exemplary method, a result of execution of computer program instructions embodied on a computer readable memory, functions performed by logic implemented in hardware, and/or interconnected means for performing functions in accordance with exemplary embodiments;
• FIG. 5 is a logic flow diagram performed by a user equipment for combination of scalar quantization and codebooks for precoder design for massive MIMO, and illustrates the operation of an exemplary method, a result of execution of computer program instructions embodied on a computer readable memory, functions performed by logic implemented in hardware, and/or interconnected means for performing functions in accordance with exemplary embodiments;
• FIG. 6 is a logic flow diagram performed by a base station for precoder design and use for massive MIMO, and illustrates the operation of an exemplary method, a result of execution of computer program instructions embodied on a computer readable memory, functions performed by logic implemented in hardware, and/or interconnected means for performing functions in accordance with exemplary embodiments;
• FIG. 7 is a logic flow diagram performed by a user equipment for precoder design and use for massive MIMO, and illustrates the operation of an exemplary method, a result of execution of computer program instructions embodied on a computer readable memory, functions performed by logic implemented in hardware, and/or interconnected means for performing functions in accordance with exemplary embodiments.
• the exemplary embodiments herein describe techniques for combination of scalar quantization and codebooks for precoder design for massive MIMO. Additional description of these techniques is presented after a system into which the exemplary embodiments may be used is described.
• FIG. 1 shows a block diagram of an exemplary system in which the exemplary embodiments may be practiced.
• N UEs 110-1 through 110-N are in wireless communication with a wireless network 100. It is assumed the UEs 110 are similar and only a possible internal configuration of UE 110-1 will be discussed herein.
• the user equipment 110 e.g., UE 110-1) includes one or more processors 120, one or more memories 125, and one or more transceivers 130 interconnected through one or more buses 127. Each of the one or more transceivers 130 includes a receiver, Rx, 132 and a transmitter, Tx, 133.
• the one or more buses 127 may be address, data, or control buses, and may include any interconnection mechanism, such as a series of lines on a motherboard or integrated circuit, fiber optics or other optical communication equipment, and the like.
• the one or more transceivers 130 are connected to one or more antennas 128.
• the one or more memories 125 include computer program code 123.
• the UE 110 includes a CSI F/B module 140, comprising one of or both parts 140-1 and/or 140-2, which may be implemented in a number of ways.
• the CSI F/B module 140 may be implemented in hardware as CSI F/B module 140-1 , such as being implemented as part of the one or more processors 120.
• the CSI F/B (feedback) module 140-1 may be implemented also as an integrated circuit or through other hardware such as a programmable gate array.
• the CSI F/B module 140 may be implemented as CSI F/B module 140-2, which is implemented as computer program code 123 and is executed by the one or more processors 120.
• the one or more memories 125 and the computer program code 123 may be configured to, with the one or more processors 120, cause the user equipment 110 to perform one or more of the operations as described herein.
• Each UE 110 communicates with eNB 170 via a wireless link 111, and there are N wireless links shown.
• the eNB 170 is a base station that provides access by wireless devices such as the UE 110 to the wireless network 100.
• the eNB 170 includes one or more processors 152, one or more memories 155, one or more network interfaces (N/W I/F(s)) 161, and one or more transceivers 160 interconnected through one or more buses 157.
• Each of the one or more transceivers 160 includes a receiver, Rx, 162 and a transmitter, Tx, 163.
• the one or more transceivers 160 are connected to multiple (e.g., many) antennas 158.
• the one or more memories 155 include computer program code 153.
• the eNB 170 includes a MIMO module 150, comprising one of or both parts 150-1 and/or 150-2, which may be implemented in a number of ways.
• the MIMO module 150 may be implemented in hardware as MIMO module 150-1, such as being implemented as part of the one or more processors 152.
• the MIMO module 150-1 may be implemented also as an integrated circuit or through other hardware such as a programmable gate array.
• the MIMO module 150 may be implemented as MIMO module 150-2, which is implemented as computer program code 153 and is executed by the one or more processors 152.
• the one or more memories 155 and the computer program code 153 are configured to, with the one or more processors 152, cause the eNB 170 to perform one or more of the operations as described herein.
• the one or more network interfaces 161 communicate over a network such as via the links 176 and 131.
• Two or more eNBs 170 communicate using, e.g., link 176.
• the link 176 may be wired or wireless or both and may implement, e.g., an X2 interface.
• the one or more buses 157 may be address, data, or control buses, and may include any interconnection mechanism, such as a series of lines on a motherboard or integrated circuit, fiber optics or other optical communication equipment, wireless channels, and the like.
• the one or more transceivers 160 may be implemented as a remote radio head (RRH) 195, with the other elements of the eNB 170 being physically in a different location from the RRH, and the one or more buses 157 could be implemented in part as fiber optic cable to connect the other elements of the eNB 170 to the RRH 195.
• RRH remote radio head
• the wireless network 100 may include a network control element (NCE) 190 that may include MME/SGW functionality, and which provides connectivity with a further network, such as a telephone network and/or a data communications network (e.g., the Internet).
• the eNB 170 is coupled via a link 131 to the NCE 190.
• the link 131 may be implemented as, e.g., an SI interface.
• the NCE 190 includes one or more processors 175, one or more memories 171, and one or more network interfaces (N/W I/F(s)) 180, interconnected through one or more buses 185.
• the one or more memories 171 include computer program code 173.
• the one or more memories 171 and the computer program code 173 are configured to, with the one or more processors 175, cause the NCE 190 to perform one or more operations.
• the wireless network 100 may implement network virtualization, which is the process of combining hardware and software network resources and network functionality into a single, software -based administrative entity, a virtual network.
• Network virtualization involves platform virtualization, often combined with resource virtualization.
• Network virtualization is categorized as either external, combining many networks, or parts of networks, into a virtual unit, or internal, providing network-like functionality to software containers on a single system. Note that the virtualized entities that result from the network virtualization are still implemented, at some level, using hardware such as processors 152 or 175 and memories 155 and 171, and also such virtualized entities create technical effects.
• the computer readable memories 125, 155, and 171 may be of any type suitable to the local technical environment and may be implemented using any suitable data storage technology, such as semiconductor based memory devices, flash memory, magnetic memory devices and systems, optical memory devices and systems, fixed memory and removable memory.
• the processors 120, 152, and 175 may be of any type suitable to the local technical environment, and may include one or more of general purpose computers, special purpose computers, microprocessors, digital signal processors (DSPs) and processors based on a multi-core processor architecture, as non-limiting examples.
• the various embodiments of the user equipment 110 can include, but are not limited to, cellular telephones such as smart phones, personal digital assistants (PDAs) having wireless communication capabilities, portable computers having wireless
• cellular telephones such as smart phones
• PDAs personal digital assistants
• portable computers having wireless
• image capture devices such as digital cameras having wireless communication capabilities
• gaming devices having wireless communication capabilities
• music storage and playback appliances having wireless communication capabilities
• Internet appliances permitting wireless Internet access and browsing, tablets with wireless communication capabilities, as well as portable units or terminals that incorporate combinations of such functions.
• Massive MIMO is considered for study in 5G considering a large number of antenna ports (16 - 64 or more).
• MU-MIMO is considered as a necessary transmission mechanism.
• Initial studies show that most of the gains come from MU-MIMO when employing such a system.
• the product codebook concept was compared against the azimuth-only baseline and a system that has ideal knowledge of the covariance matrix (covMTX).
• the baseline was a system with four transmission antennas (4TX), using transmission mode 9 (TM9), single user (SU) and multi-user (MU) MIMO, with 4 bits of LTE codebook feedback.
• the LTE Rel-10 style product codebook versions used SU-MIMO with 40 ports (40 TX, 40 transmission antennas) or MU-MIMO with 40 ports, and 8 bits of codebook feedback.
• FD-MIMO is assumed to mean the same as the term massive MIMO.
• transmission ports are in the form of a rectangular array with cross-polarized antenna elements. It is shown that a precoder for a rectangular array can be represented with a 3-part (W3W1W2) product codebook structure and one exemplary proposal is to use a combination of scalar quantization for Wi and vector quantization for W 2 , W3 to increase the quantization resolution without affecting UE search complexity.
• scalar quantization is a mapping of an input value x into a finite number of output values, y: Q: x ⁇ y.
• Vector quantization works by dividing a large set of points (i.e., vectors) into groups having approximately the same number of points in and closest to them. Each group is represented by its centroid point.
• the invention comprises the following in an exemplary embodiment.
• the matrix comprises the correlation information in the channel - both in the horizontal and in the vertical dimensions.
• W 1 does not change rapidly and needs to be refreshed in the order of hundreds of milliseconds. It may be sufficient to obtain a wideband characterization oi W ⁇ . It is envisioned that a UE will use a long averaging window or filter for in time and frequency.
• the matrix W 3 is a diagonal matrix that is intended for tracking small changes in W i .
• vector quantization e.g., codebooks
• FIG. 3 illustrates a 3D planar antenna structure 300 (e.g., a version of antennas 158) where each column is a cross-polarized array.
• the right leaning elements 310 are +45° polarized and the left leaning elements 320 are -45° polarized.
• N R the number of rows of antenna elements
• N c the number of columns of antenna elements.
• the total number of antenna elements is then 2N R N C including both +/-45 0 (plus and minus 45 degrees) polarized antennas.
• the total number of transmit ports for massive MIMO is 2N R N C .
• R the covariance matrix
• a general form for the Rel-10 8Tx rank-1 precoder (as represented in the codebook) for a given layer can be (approximately) decomposed into two parts, Wi and W2 written as: where w denotes a vector of coefficients common to the +45° and the -45° antenna elements and a represents a co-phasing scalar, a £ QPSK.
• W 2 matrix is a square unitary matrix.
• W 2 as mentioned in Equation (1) only shows the co-phasing entries, but W 2 as specified in Rel-10 comprises both selection entries and co-phasing entries.
• W 2 as specified in Rel-10 comprises both selection entries and co-phasing entries.
• one underlying design principle is that Wi entries are long-term and need to be updated less frequently than W 2 entries.
• Equation (1) the ⁇ indicates that the design principle behind the Rel-10 8TX rank- 1 precoder assumes that the precoder w R1 for each layer represents azimuth coefficients only since the Rel-10 8Tx precoder was designed for azimuth-only antenna arrays.
• the W 2 matrix is a square unitary matrix.
• the Wi matrix has a block diagonal structure where the two non-zero blocks are identical (both equal to w az ®w ei ).
• the w az and w el in general are accounting for both polarizations identically, meaning that they can be computed from a single covariance matrix that is an average of a first covariance matrix for the +45 co-pol (co-polarized) antennas and a second covariance matrix for the -45 co-pol antennas.
• An alternative embodiment is to relax the constraint that the upper left and lower right block diagonal blocks in Wi are equal.
• An exemplary proposal herein is to use a high resolution scalar quantization for one or more components of the Wi matrix - either w az or w e i or both may be scalar-quantized.
• the quantized coefficients are considered to be valid for a long term (compared to W 2 and W3) and will be updated less frequently (compared to W 2 and W3). It is known from internal results that the conventional VQ approach for precoder quantization using codebooks gets saturated at around 10 bits. Further increasing the size will also have serious search-complexity concerns (currently a maximum size of 8 bits is considered in LTE).
• Wi is a matrix
• the vector x q is of size N R N C x 1 and represents correlation among the N R N C co-polar antenna elements.
• the N R N C co-polar antenna elements include both horizontally (azimuth adaptive) and vertically (elevation adaptive) positioned antenna elements. This example removes the constraints imposed by a Kronecker product of azimuth and elevation vectors and is more generic to handle array types not conforming to FIG. 3.
• the vector x q can be computed based on an eigendecomposition of a covariance matrix that is computed to be the average of two covariance matrices, the first being a covariance matrix for the +45 co-polar antenna elements and the second being a covariance matrix for the -45 co-polar antenna elements.
• the diagonal entries can also be matrices in certain cases and W 1 can be
• Q(Mi 45 )' Q(M 2 45 ) can be obtained from the first and second dominant eigenvectors of the covariance matrix for the co-polarized +45 elements respectively.
• @( ⁇ 45 )' Q(M 2 45 ) can be obtained from the first and second dominant eigenvectors of the covariance matrix for the co-polarized -45 elements respectively.
• the function Q ⁇ .) here represents scalar quantization even though it is expressed as operating on a vector argument.
• An example of such a function is an element by element independent quantization of the set of phases associated with the vector argument.
• a composite covariance matrix is defined as a matrix comprised of correlations among all the +45 and -45 antenna elements.
• the term Q(u ⁇ 45 ) can be obtained from the first dominant eigenvector of the composite covariance matrix but only the elements of the eigenvector that are associated with the +45 antenna elements.
• the term Q(v ⁇ 45 ) can be obtained from the first dominant eigenvector of the composite covariance matrix but only the elements of the eigenvector that are associated with the -45 antenna elements.
• Q(u 45 ) can be obtained from the second dominant eigenvector of the composite covariance matrix but only the elements of the eigenvector that are associated with the +45 antenna elements.
• Q(u ⁇ 45 ) can be obtained from the second dominant eigenvector of the composite covariance matrix but only the elements of the eigenvector that are associated with the -45 antenna elements.
• the quantization function Q(.) quantizes the phases of each of the elements using an M-PSK constellation, where amplitude differences among the different elements is not retained (each element is of equal amplitude). Also note that the same value of Wi may be suitable for multiple layers (in conjunction with a different W 2 for each layer). Alternatively, Q(.) can also quantize both phase and gain of each element.
• An exemplary proposal is to design W 2 only for co-phasing (across polarizations) and W3 for allowing small perturbations of Wi.
• Wi and W3 are considered to be valid over a short-term and expected to be updated more often (compared to W 2 ).
• Wi will be determined and quantized first at the UE.
• the scalar quantization of can be obtained by operating a scalar independently on each element of one or more eigenvectors derived from the estimated channel. It is also possible to use a scalar quantizer, where the quantization of an element is dependent on the quantized or unquantized value of another element - this process may add some implementation complexity with certain performance benefits. Irrespective of exactly the process used at the UE to achieve quantization, an eNB will be allowed to assume that an independent element-by-element mapping of the quantization output to the quantized value is sufficient to reconstruct W i .
• W 1 can be based on the eigenvectors of a covariance matrix obtained by averaging covariance matrices across a certain time and frequency window. Based on the quantized value of Wi, W 2 and W3 will be determined by an exhaustive search procedure considering a certain cost- function.
• An example of a cost-function for determining W 2 can be expressed as max ⁇ trace(I*V r WlRW 1 W 2 ) ⁇ ,
• R is an estimate of an appropriately averaged covariance matrix and trace of a matrix is defined as the sum of the diagonal elements.
• FIG. 4 is a logic flow diagram performed by a base station for combination of scalar quantization and codebooks for precoder design for massive MIMO.
• This figure illustrates the operation of an exemplary method, a result of execution of computer program instructions embodied on a computer readable memory, functions performed by logic implemented in hardware, and/or interconnected means for performing functions in accordance with exemplary embodiments.
• the blocks in FIG. 4 are performed by a base station such as eNB 170, e.g., under the control in part by the MIMO module 150.
• the blocks are assumed herein to be performed by the eNB 170.
• a cellular system is being used as an example, but the instant example is not limited to a cellular system.
• the exemplary embodiments could be applicable to Wi-Fi or other wireless systems.
• the eNB 170 transmits reference signals to UEs using (e.g., massive) MIMO.
• MIMO uses an antenna array such as array 300 with cross-polarized antenna elements.
• the eNB 170 receives CSI from the UEs.
• the CSI corresponds to each part (e.g., Wi, W 2 , and W3) of a three-part product codebook structure, as the codebook structure is described above.
• the eNB 170 determines a precoder for a given layer using the CSI of the three -part product codebook structure corresponding to that layer.
• the eNB 170 repeats block 430 for each UE and each layer.
• the eNB 170 in block 450 applies the determined precoders to information to be transmitted to corresponding UEs, and then transmits precoded information to the UEs using (e.g., massive) MIMO (e.g., using an antenna array with cross-polarized antenna elements) in block 460.
• massive MIMO e.g., using an antenna array with cross-polarized antenna elements
• FIG. 5 a logic flow diagram is shown that is performed by a user equipment for combination of scalar quantization and codebooks for precoder design for massive MIMO.
• FIG. 5 illustrates the operation of an exemplary method, a result of execution of computer program instructions embodied on a computer readable memory, functions performed by logic implemented in hardware, and/or interconnected means for performing functions in accordance with exemplary embodiments.
• the blocks in FIG. 5 are assumed to be performed by a single one (e.g., UE 110-1) of the UEs 110. For ease of reference, this UE will be referred to as UE 110. Note that the UE 110 may perform the blocks under control in part by the CSI F/B module 140.
• the UE 110 receives reference signals from a base station based on (e.g., massive) MIMO (e.g., using an antenna array with cross-polarized antenna elements).
• the UE 110 in block 510 determines CSI corresponding to each part of a three-part product codebook structure (W3W2W1).
• the UE 110 reports the CSI corresponding to each part of a three-part product codebook structure to the base station.
• the UE 110 receives previously precoded information from the base station using (e.g., massive) MIMO, which uses an antenna array with cross-polarized antenna elements. That is, the base station has (see block 450 of FIG.
• the previous precoding is based on the reported CSI. It is noted that the UE 110 would perform decoding of the received information, as is known.
• the reporting (e.g., blocks 505, 510, and 515) by the UE 110 may be performed based on certain feedback granularities (block 525).
• the UE 110 reports Wi at a faster rate relative to the rate(s) for W2 and W3.
• the rates of reporting for W2 and W3 may be the same or different.
• the rates are time granularities.
• the UE 110 reports Wi based on wideband and reports W2 and W3 based on narrow band (e.g., subband). These reports are frequency (i.e., bandwidth) granularities.
• the UE 110 may determine CSI for the three-part product codebook in a number of ways.
• One of those ways is illustrated by blocks 540-555.
• the UE 110 in block 540 determines Wi and then quantizes Wi in block 545.
• the UE 110 performs in block 550 an exhaustive search procedure considering a certain cost-function to determine W2 and W3. Note that the search may take into account the quantized value of Wi.
• the UE 110 quantizes W2 and W3.
• FIG. 5 illustrates a non-limiting and non-exclusive set of these options.
• the UE 110 can perform (block 560) scalar quantization (e.g., high resolution) for azimuthal and elevational directions in one example.
• the UE 110 performs (block 565) scalar quantization (e.g., high resolution) for the azimuthal direction, and performs (block 570) vector quantization for the elevational direction.
• scalar quantization e.g., high resolution
• the UE 110 performs (block 565) scalar quantization (e.g., high resolution) for the azimuthal direction, and performs (block 570) vector quantization for the elevational direction.
• the opposite may be performed, e.g., vector quantization only for the azimuth dimension of the precoder part and
• FIG. 6 is a logic flow diagram performed by a base station for precoder design and use for massive MIMO.
• This figure also illustrates the operation of an exemplary method, a result of execution of computer program instructions embodied on a computer readable memory, functions performed by logic implemented in hardware, and/or interconnected means for performing functions in accordance with exemplary embodiments.
• the blocks in FIG. 6 are performed by a base station such as eNB 170, e.g., under the control in part by the MIMO module 150.
• the blocks are assumed herein to be performed by the eNB 170.
• a cellular system is being used as an example, but the instant example is not limited to a cellular system.
• the exemplary embodiments could be applicable to Wi-Fi or other wireless systems.
• the eNB 170 determines a precoder for a given layer and for a user equipment.
• the precoder comprises a three-part product codebook structure.
• the determining uses channel state information from the user equipment for the three-part product codebook structure.
• the channel state information corresponds to a plurality of antenna elements in at least a two-dimensional array of cross-polarized antenna elements.
• the eNB 170 applies the determined precoder to information for the layer to be transmitted to the user equipment.
• the eNB 170 transmits the precoded information for the layer to the user equipment using the plurality of antenna elements in the at least two-dimensional array of cross-polarized antenna elements.
• Example 3 The method of example 2, wherein the matrix W 2 comprises co-phasing information.
• Example 4 The method of example 3, wherein the channel state information for the matrix W 2 is quantized with a few bits using vector quantization.
• Example 5 The method of example 4, wherein the few bits are less than or equal to two bits per layer.
• Example 6 The method of any one of examples 3 to 5, wherein the channel state information for the matrix W 2 is obtained on a per sub-band level of granularity in frequency and five to 10 milliseconds granularity in time.
• Example 7 The method of any one of examples 2 to 6, wherein the matrix comprises correlation information in the channel, in both horizontal and vertical dimensions.
• Example 8 The method of example 7, where channel state information for the matrix is refreshed in the order of hundreds of milliseconds.
• Example 9 The method of any one of examples 7 to 8, wherein the channel state information for the matrix W 1 is obtained via a wideband characterization.
• Example 10 The method of any one of examples 7 to 9, wherein the matrix W 1 is constrained to a dual Kronecker structure having one Kronecker structure comprising azimuth and elevation elements and another Kronecker structure due to polarization.
• Example 11 The method of any one of examples 2 to 10, wherein the matrix W 3 is a diagonal matrix that tracks small changes in the matrix W ⁇ .
• Example 12 The method of example 11, wherein the channel state information for the matrix W is quantized using a few bits using vector quantization.
• Example 13 The method of example 12, wherein the few bits are less than or equal to two bits per layer.
• Example 14 The method of any one of examples 11 to 13, wherein the channel state information for the matrix W 3 is obtained on a per sub-band level of granularity in frequency and five to 10 milliseconds granularity in time.
• Example 15 The method of any one of examples 2 to 14, wherein the precoder is further given by the following:
• W 3 WiW 2 [D el ®D az ]
• a represents a co-phasing scalar
• diag() indicates matrix diagonalization
• exp(x) is e x
• ⁇ g> is a Kronecker product.
• Example 16 The method of any of examples 1 to 15, wherein: [0084] determining a precoder is performed for a plurality of layers for each of a plurality of user equipment;
• transmitting comprises transmitting the precoded information for all of the plurality of layers and plurality of user equipment.
• Example 17 The method of any of examples 1 to 16, further comprising, prior to the determining the precoder:
• this figure is a logic flow diagram performed by a user equipment for precoder design and use for massive MIMO.
• This figure further illustrates the operation of an exemplary method, a result of execution of computer program instructions embodied on a computer readable memory, functions performed by logic implemented in hardware, and/or interconnected means for performing functions in accordance with exemplary embodiments.
• the blocks in FIG. 7 are assumed to be performed by a single one (e.g., UE 110-1) of the UEs 110. For ease of reference, this UE will be referred to as UE 110. Note that the UE 110 may perform the blocks under control in part by the CSI F/B module 140.
• the UE 110 receives reference signal information for a layer that has been transmitted from a base station.
• the reference signal information was transmitted using a plurality of antenna elements in at least a two-dimensional array of cross-polarized antenna elements.
• the UE 110 determines, using the reference signal information, channel state information corresponding to each part of a three-part product codebook structure for the layer.
• the UE 110 reports the determined channel state information corresponding to each part of the three-part product codebook structure to the base station.
• the UE 110 received previously precoded information for the layer transmitted from the base station using the plurality of antenna elements, where the previously precoded information is based on the reported channel state information.
• Example 20 The method of example 19, wherein the matrix W 2 comprises co-phasing information.
• Example 21 The method of example 20, wherein determining the channel state information further comprises quantizing the channel state information for the matrix W 2 with a few bits using vector quantization.
• Example 22 The method of example 21, wherein the few bits are less than or equal to two bits per layer.
• Example 23 The method of any one of examples 20 to 22, wherein determining the channel state information further comprises obtaining the channel state information for the matrix W 2 on a per sub-band level of granularity in frequency and five to 10 milliseconds granularity in time.
• Example 24 The method of any one of examples 19 to 23, wherein the matrix W 1 comprises correlation information in the channel, in both horizontal and vertical dimensions.
• Example 25 The method of example 24, wherein determining the channel state information further comprises refreshing channel state information for the matrix in the order of hundreds of milliseconds.
• Example 26 The method of any one of examples 24 to 25, wherein determining the channel state information further comprises obtaining the channel state information for the matrix via a wideband characterization.
• Example 27 The method of any one of examples 24 to 26, wherein the matrix is constrained to a dual Kronecker structure having one Kronecker structure comprising azimuth and elevation elements and another Kronecker structure due to polarization.
• Example 28 The method of any one of examples 19 to 27, wherein the matrix W 3 is a diagonal matrix that tracks small changes in the matrix W ⁇ .
• Example 29 The method of example 28, wherein determining channel state information further comprises quantizing the channel state information for the matrix W 3 using a few bits using vector quantization.
• Example 30 The method of example 29, wherein the few bits are less than or equal to two bits per layer.
• Example 31 The method of any one of examples 28 to 30, wherein determining channel state information further comprises obtaining the channel state information for the matrix W 3 on a per sub-band level of granularity in frequency and five to 10 milliseconds granularity in time.
• Example 32 The method of any one of examples 18 to 31 , wherein the precoder is further given by the following:
• W 3 WiW 2 [D el ®D az ]
• a represents a co-phasing scalar
• diag() indicates matrix diagonalization
• exp(x) is e x
• ⁇ g> is a Kronecker product.
• Example 33 The method of any of examples 18 to 32, wherein:
• receiving reference signal information, determining channel state information and reporting are performed for each of a plurality of layers;
• receiving previously precoded information further comprises receiving the previously precoded information for each of the plurality of layers.
• Example 34 A computer program, comprising code for performing any of the methods in claims 1 to 33, when the computer program is run on a processor.
• Example 35 The computer program according to example 34, wherein the computer program is a computer program product comprising a computer-readable medium bearing computer program code embodied therein for use with a computer.
• Example 36 An apparatus, comprising:
• [00115] means for determining a precoder for a given layer and for a user equipment, wherein the precoder comprises a three-part product codebook structure, wherein the determining uses channel state information from the user equipment for the three-part product codebook structure, and wherein the channel state information corresponds to a plurality of antenna elements in at least a two-dimensional array of cross-polarized antenna elements;
• [00116] means for applying the determined precoder to information for the layer to be transmitted to the user equipment; and [00117] means for transmitting the precoded information for the layer to the user equipment using the plurality of antenna elements in the at least two-dimensional array of cross-polarized antenna elements.
• Example 38 The apparatus of example 37, wherein the matrix W 2 comprises co-phasing information.
• Example 39 The apparatus of example 38, wherein the channel state information for the matrix W 2 is quantized with a few bits using vector quantization.
• Example 40 The apparatus of example 39, wherein the few bits are less than or equal to two bits per layer.
• Example 41 The apparatus of any one of examples 38 to 40, wherein the channel state information for the matrix W 2 is obtained on a per sub-band level of granularity in frequency and five to 10 milliseconds granularity in time.
• Example 42 The apparatus of any one of examples 37 to 41, wherein the matrix comprises correlation information in the channel, in both horizontal and vertical dimensions.
• Example 43 The apparatus of example 42, where channel state information for the matrix W 1 is refreshed in the order of hundreds of milliseconds.
• Example 44 The apparatus of any one of examples 42 to 43, wherein the channel state information for the matrix is obtained via a wideband characterization.
• Example 45 The apparatus of any one of examples 42 to 44, wherein the matrix W 1 is constrained to a dual Kronecker structure having one Kronecker structure comprising azimuth and elevation elements and another Kronecker structure due to polarization.
• Example 46 The apparatus of any one of examples 37 to 45, wherein the matrix W 3 is a diagonal matrix that tracks small changes in the matrix W ⁇ .
• Example 47 The apparatus of example 46, wherein the channel state information for the matrix W is quantized using a few bits using vector quantization.
• Example 48 The apparatus of example 47, wherein the few bits are less than or equal to two bits per layer.
• Example 49 The apparatus of any one of examples 46 to 48, wherein the channel state information for the matrix W 3 is obtained on a per sub-band level of granularity in frequency and five to 10 milliseconds granularity in time.
• Example 50 The apparatus of any one of examples 37 to 49, wherein the precoder is further given by the following:
• W 3 WiW 2 [D el ®D az ]
• a represents a co-phasing scalar
• diag() indicates matrix diagonalization
• exp(x) is e x
• ⁇ g> is a Kronecker product.
• Example 51 The apparatus of any of examples 36 to 50, wherein:
• the means for determining determines a precoder for a plurality of layers for each of a plurality of user equipment
• the means for applying the determined precoder to information for the layer performs the applying for each of the plurality of layers
• the means for transmitting comprises means for transmitting the precoded information for all of the plurality of layers and plurality of user equipment.
• Example 52 The apparatus of any of examples 36 to 51, further comprising, prior to determining the precoder:
• [00139] means for transmitting to the user equipment reference signal information for the layer using the plurality of antenna elements in the at least the
• [00140] means for receiving the channel state information from the user equipment in response to the transmitting of the reference signal information.
• Example 53 An apparatus, comprising:
• [00142] means for receiving at a user equipment reference signal information for a layer that has been transmitted from a base station, the reference signal information transmitted using a plurality of antenna elements in at least a two-dimensional array of cross-polarized antenna elements;
• [00143] means for determining, at the user equipment and using the reference signal information, channel state information corresponding to each part of a three-part product codebook structure for the layer; [00144] means for reporting by the user equipment the determined channel state information corresponding to each part of the three-part product codebook structure to the base station; and
• Example 55 The apparatus of example 54, wherein the matrix W 2 comprises co-phasing information.
• Example 56 The apparatus of example 55, wherein the means for determining the channel state information further comprises means for quantizing the channel state information for the matrix W 2 with a few bits using vector quantization.
• Example 57 The apparatus of example 56, wherein the few bits are less than or equal to two bits per layer.
• Example 58 The apparatus of any one of examples 55 to 57, wherein the means for determining the channel state information further comprises means for obtaining the channel state information for the matrix W 2 on a per sub-band level of granularity in frequency and five to 10 milliseconds granularity in time.
• Example 59 The apparatus of any one of examples 54 to 58, wherein the matrix comprises correlation information in the channel, in both horizontal and vertical dimensions.
• Example 60 The apparatus of example 59, wherein the means for determining the channel state information further comprises means for refreshing channel state information for the matrix W 1 in the order of hundreds of milliseconds.
• Example 61 The apparatus of any one of examples 59 to 60, wherein the means for determining the channel state information further comprises means for obtaining the channel state information for the matrix W 1 via a wideband characterization.
• Example 62 The apparatus of any one of examples 59 to 61, wherein the matrix W 1 is constrained to a dual Kronecker structure having one Kronecker structure comprising azimuth and elevation elements and another Kronecker structure due to polarization.
• Example 63 The apparatus of any one of examples 54 to 62, wherein the matrix W 3 is a diagonal matrix that tracks small changes in the matrix W ⁇ .
• Example 64 The apparatus of example 63, wherein the means for determining channel state information further comprises means for quantizing the channel state information for the matrix W 3 using a few bits using vector quantization.
• Example 65 The apparatus of example 61, wherein the few bits are less than or equal to two bits per layer.
• Example 66 The apparatus of any one of examples 63 to 65, wherein the means for determining channel state information further comprises means for obtaining the channel state information for the matrix W 3 on a per sub-band level of granularity in frequency and five to 10 milliseconds granularity in time.
• Example 67 The apparatus of any one of examples 53 to 66, wherein the precoder is further given by the following:
• a represents a co-phasing scalar
• diag() indicates matrix diagonalization
• exp(x) is e x
• ⁇ g> is a Kronecker product.
• Example 68 The apparatus of any of examples 53 to 67, wherein:
• the means for receiving reference signal information, means for determining channel state information and means for reporting operate for each of a plurality of layers;
• the means for receiving previously precoded information further comprises means for receiving the previously precoded information for each of the plurality of layers.
• Example 69 A base station comprising any of the apparatus of examples 36 to 52.
• Example 70 A user equipment comprising any of the apparatus of examples 53 to 68.
• Example 71 A system comprising any of the apparatus of examples 36 to 52 and any of the apparatus of examples 53 to 68.
• Embodiments herein may be implemented in software (executed by one or more processors), hardware (e.g., an application specific integrated circuit), or a combination of software and hardware.
• the software e.g., application logic, an instruction set
• a "computer-readable medium” may be any media or means that can contain, store, communicate, propagate or transport the instructions for use by or in connection with an instruction execution system, apparatus, or device, such as a computer, with one example of a computer described and depicted, e.g., in FIG. 1.
• a computer-readable medium may comprise a computer-readable storage medium (e.g., memories 125, 155, 171 or other device) that may be any media or means that can contain or store the instructions for use by or in connection with an instruction execution system, apparatus, or device, such as a computer.
• a computer-readable storage medium does not comprise propagating signals.
• the different functions discussed herein may be performed in a different order and/or concurrently with each other. Furthermore, if desired, one or more of the above-described functions may be optional or may be combined.
• UE user equipment e.g., a mobile station
• Wi-Fi wireless fidelity s local area wireless technology xpol cross polarizations

Landscapes

• Engineering & Computer Science (AREA)
• Computer Networks & Wireless Communication (AREA)
• Signal Processing (AREA)
• Physics & Mathematics (AREA)
• Mathematical Physics (AREA)
• Radio Transmission System (AREA)
• Mobile Radio Communication Systems (AREA)

Applications Claiming Priority (2)

Publications (1)

Family

ID=55262809

Family Applications (1)

Country Status (2)

Families Citing this family (8)

Family Cites Families (1)

• 2016
  • 2016-01-29 EP EP16701956.1A patent/EP3251227A1/de not_active Withdrawn
  • 2016-01-29 WO PCT/EP2016/051909 patent/WO2016120443A1/en active Application Filing

Also Published As

Similar Documents

Legal Events