WO2017000995A1 - Station de base et procédé d'exploitation d'une station de base - Google Patents

Station de base et procédé d'exploitation d'une station de base Download PDF

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Publication number
WO2017000995A1
WO2017000995A1 PCT/EP2015/064883 EP2015064883W WO2017000995A1 WO 2017000995 A1 WO2017000995 A1 WO 2017000995A1 EP 2015064883 W EP2015064883 W EP 2015064883W WO 2017000995 A1 WO2017000995 A1 WO 2017000995A1
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WO
WIPO (PCT)
Prior art keywords
correlation matrix
uplink
base station
downlink
user equipment
Prior art date
Application number
PCT/EP2015/064883
Other languages
English (en)
Inventor
Maxime Guillaud
Alexis DECURNINGE
Dirk Slock
Original Assignee
Huawei Technologies Co., Ltd.
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Huawei Technologies Co., Ltd. filed Critical Huawei Technologies Co., Ltd.
Priority to PCT/EP2015/064883 priority Critical patent/WO2017000995A1/fr
Priority to CN201580080228.9A priority patent/CN107646172B/zh
Publication of WO2017000995A1 publication Critical patent/WO2017000995A1/fr

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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
    • 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
    • H04B7/0617—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 for beam forming
    • 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
    • H04B7/0684—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 using different training sequences per antenna
    • 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
    • H04B7/0686—Hybrid systems, i.e. switching and simultaneous transmission
    • H04B7/0691—Hybrid systems, i.e. switching and simultaneous transmission using subgroups of transmit antennas

Definitions

  • the present invention relates to mobile communications.
  • the present invention relates to a multi-antenna base station and a method of operating a multi- antenna base station.
  • multiple-antenna transceivers in a base station and a user equipment can improve the performance of a wireless communication link.
  • MIMO Multiple-ln-Multiple-Out
  • CSI channel state information
  • a training sequence having at least a length or duration N is required to estimate a channel matrix representing the channel state information, if no prior information about the statistics (including correlation) of the channel is available. Consequently, for a coherence time T, the fraction of channels N that can be dedicated to data cannot be larger than (T- N)/T, which is problematic for large N (massive MIMO case).
  • a further known approach is based on a model of the user equipment and/or the geometry of the array of antennas (Uniform Linear Array, Uniform Circular Array). This approach, however, is very sensitive to a change of the position and/or orientation of the antenna array and, thus, to the difference between uplink and downlink frequencies. Consequently, this approach has a rather limited applicability in practice.
  • the invention relates to a base station configured to
  • the base station comprises an antenna array with a plurality of antennas configured to establish a duplex communication channel with the at least one user equipment, wherein the duplex communication channel is associated with a correlation matrix pair comprising a downlink correlation matrix R, describing the channel state in the downlink direction and an uplink correlation matrix Ri UL describing the channel state in the uplink direction.
  • the base station comprises a processor configured to, in a training phase, generate for a plurality of positions of the at least one user equipment or a plurality of times a plurality of correlation matrix pairs, wherein the processor is configured to determine each uplink correlation matrix R UI - of the plurality of correlation matrix pairs (R,, Ri UL ) on the basis of a respective uplink training signal received from the at least one user equipment and to associate each uplink correlation matrix Ri UL with a corresponding downlink correlation matrix R,, and, in an exploitation phase, determine a further uplink correlation matrix Rj UL on the basis of a further uplink training signal received from the at least one user equipment and estimate a further downlink correlation matrix Rj corresponding to the further uplink correlation matrix Rj UL on the basis of the further uplink correlation matrix Rj UL and the plurality of correlation matrix pairs (R,, R UL ).
  • the processor is configured to estimate the further downlink correlation matrix Rj
  • a matrix interpolation scheme improves the accuracy of estimating the further downlink correlation matrix Rj corresponding to the further uplink correlation matrix Rj UL , while keeping the size of the dictionary, i.e. the number of correlation matrix pairs (R,, R UL ) reasonably small.
  • the processor is configured to estimate the further downlink correlation matrix Rj corresponding to the further uplink correlation matrix Rj UL on the basis of the further uplink correlation matrix Rj UL and the plurality of correlation matrix pairs (R,, Ri UL ) by using the matrix interpolation scheme defined by the following equation: wherein Y is a matrix in the space of positive definite matrices SN(C), N is the number of antennas of the antenna array used in the downlink direction, w, are interpolation weights calculated on the basis of the further uplink correlation matrix Rj UL and the uplink correlation matrices Ri UL of the plurality of correlation matrix pairs, d( , ) defines a distance metric in SN(C), and K is the number of correlation matrix pairs (R,, R UL ).
  • the distance metric d( , ) is an affine invariant Riemannian distance metric defined by the following equation:
  • the processor is configured to determine the interpolation weights w, by a nearest neighbor method according to the following equation
  • the processor is configured to determine the interpolation weights w, by a self-interpolation method according to the following equation:
  • the decreasing kernel function ⁇ is defined by the following equation:
  • the processor is configured to return from the exploitation phase to the training phase, in case the distance d(Rj UL , Ri UL ) between the further uplink correlation matrix Rj UL and each uplink correlation matrix Ri UL of the plurality of correlation matrix pairs (R,, Ri UL ) is larger than a distance threshold.
  • the corresponding downlink correlation matrix R received from the user equipment by the base station is determined by the user equipment on the basis of a downlink training signal sent by the base station.
  • the processor is configured to perform the training phase and the exploitation phase in chronologically successive intervals, in chronologically interleaved intervals or simultaneously.
  • the antenna array is configured to use a first subset of the plurality of antennas in the downlink direction and a second subset of the plurality of antennas in the uplink direction.
  • the first subset of antennas and the second subset of antennas can be identical, overlapping, or disjoint.
  • the downlink correlation matrix R is of dimension NxN
  • M antennas used in the uplink direction the uplink correlation matrix Ri UL is of size MxM.
  • the method according to the second aspect of the invention can be performed by the base station according to the first aspect of the invention. Further features of the method according to the second aspect of the invention result directly from the functionality of the base station according to the first aspect of the invention and its different implementation forms described above.
  • the invention relates to a computer program comprising program code for performing the method according to the second aspect of the invention when executed on a computer.
  • FIG. 1 shows a schematic diagram of a communication scenario including a base station according to an embodiment
  • Fig. 2 shows a schematic diagram of a communication scenario including a base station according to an embodiment
  • Fig. 3 shows a schematic diagram of a method of operating a base station according to an embodiment
  • Fig. 4 shows a diagram showing an estimate of the mean square error as a function of the number of correlation matrix pairs for base stations according to different embodiments
  • Figure 1 shows a schematic diagram of a communication scenario including a base station 100 according to an embodiment.
  • the base station 100 is configured to
  • the base station 100 comprises an antenna array 101 a, wherein the antenna array comprises at least two antennas and is configured to establish a duplex communication channel with the at least one user equipment 105a-f.
  • the duplex communication channel is associated with a correlation matrix pair comprising a downlink correlation matrix R, describing the channel state in the downlink direction and an uplink correlation matrix Ri UL describing the channel state in the uplink direction.
  • the antenna array 101 a is configured to use a first subset of its antennas in the downlink direction and a second subset of its antennas in the uplink direction.
  • the first subset of antennas and the second subset of antennas can be identical, overlapping, or disjoint.
  • the downlink correlation matrix R is of dimension NxN
  • M antennas used in the uplink direction the uplink correlation matrix Ri UL is of size MxM.
  • the base station 100 comprises a processor 103 configured to, in a training phase, generate for a plurality of positions of the one or more user equipments 105a-f or a plurality of times a plurality of correlation matrix pairs, wherein the processor 103 is configured to determine each uplink correlation matrix Ri UL of the plurality of correlation matrix pairs (R,, R UL ) on the basis of a respective uplink training signal received from the one or more user equipments 105a-f and to associate each uplink correlation matrix Ri UL with a corresponding downlink correlation matrix R,.
  • a processor 103 configured to, in a training phase, generate for a plurality of positions of the one or more user equipments 105a-f or a plurality of times a plurality of correlation matrix pairs, wherein the processor 103 is configured to determine each uplink correlation matrix Ri UL of the plurality of correlation matrix pairs (R,, R UL ) on the basis of a respective uplink training signal received from the one or more user equipments 105a-f and to
  • the processor 103 of the base station 100 is configured, in an exploitation phase, to determine a further uplink correlation matrix Rj UL on the basis of a further uplink training signal received from the at least one user equipment and estimate a further downlink correlation matrix Rj corresponding to the further uplink correlation matrix Rj UL on the basis of the further uplink correlation matrix Rj UL and the plurality of correlation matrix pairs (Ri, Ri UL ).
  • the processor 103 is configured to estimate the further downlink correlation matrix Rj corresponding to the further uplink correlation matrix Rj UL on the basis of the further uplink correlation matrix Rj UL and the plurality of correlation matrix pairs (R,, Ri UL ) by using a matrix interpolation scheme.
  • the matrix interpolation scheme is defined by the following equation: , (2)
  • Y is a matrix in the space of positive definite matrices SN(C)
  • N is the number of antennas of the antenna array 101 a used in the downlink direction
  • w are interpolation weights calculated on the basis of the further uplink correlation matrix Rj UL and the uplink correlation matrices R UL of the plurality of correlation matrix pairs
  • d( , ) defines a distance metric in SN(C)
  • K is the number of correlation matrix pairs (R,, R UL ).
  • the distance metric d( , ) is an affine invariant Riemannian distance metric defined by the following equation: wherein Xi and X2 are matrices in SN(C) and
  • the processor 103 is configured to determine the interpolation weights Wi by a kernel interpolation method according to the following equation:
  • ⁇ is a decreasing kernel function.
  • the processor 103 is configured to return from the exploitation phase to the training phase, in case the distance d(Rj UL , Ri UL ) between the further uplink correlation matrix Rj UL and each uplink correlation matrix Ri UL of the plurality of correlation matrix pairs (Ri, Ri UL ) is larger than a distance threshold. This is advantageous in case the dictionary of correlation matrix pairs (R,, R UL ) determined during the training phase is not sufficient to determine the further uplink correlation matrix R UL , for instance, by means of one of the above described matrix interpolation methods.
  • the corresponding downlink correlation matrix R can be received by the base station 100 from the user equipment 105a-g or is determined by the base station 100 on the basis of information, in particular an estimate of a channel matrix H, (as defined in above equation (1 )), fed back from the user equipment 105a-g on the basis of a downlink training signal sent by the base station 100.
  • the channel matrix H as defined in above equation (1 )
  • corresponding downlink correlation matrix R received from the user equipment 105a-g by the base station 100 is determined by the user equipment 105a-g on the basis of a downlink training signal sent by the base station 100.
  • the processor 103 is configured to perform the training phase and the exploitation phase in chronologically successive intervals, in chronologically interleaved intervals or simultaneously.
  • a duplex communication channel with the at least one user equipment 105a-g is established using the antenna array 101 having a plurality of antennas, wherein the duplex communication channel is associated with a correlation matrix pair comprising a downlink correlation matrix R, describing the channel state in the downlink direction and an uplink correlation matrix Ri UL describing the channel state in the uplink direction.
  • a plurality of correlation matrix pairs are generated for a plurality of positions of the at least one user equipment 105a-g or a plurality of times, wherein each uplink correlation matrix Ri UL of the plurality of correlation matrix pairs (R,, Ri UL ) is determined on the basis of a respective uplink training signal received from the at least one user equipment 105a-g and wherein each uplink correlation matrix R UI - is associated with a corresponding downlink correlation matrix R,.
  • a further uplink correlation matrix Rj UL is determined on the basis of a further uplink training signal received from the at least one user equipment 105a-g and a further downlink correlation matrix Rj corresponding to the further uplink correlation matrix Rj UL is estimated on the basis of the further uplink correlation matrix Rj UL and the plurality of correlation matrix pairs (R,, R UL ).
  • simulations have been performed using K (with K equal to 50, 100, 150, 300 or 1500) pairs of UL/DL correlation matrices in the base station 100.
  • K each correlation matrix pair has been generated by randomly placing a single antenna user equipment surrounded by a ring of scatterers and by computing the corresponding correlation matrices as a function of the UL/DL wavelength.
  • the uplink (UL) and downlink (DL) channels are assumed to operate at different frequencies (uplink at 1 .9 GHz and downlink at 1 .8 GHz).
  • the covariance matrices are estimated by the sample covariance computed from 1000 realizations of the fast-fading process W,, as defined in above equation (1 ).
  • FIG. 4 shows a diagram showing an estimate of the mean square error as a function of the number of correlation matrix pairs for the above described cases.
  • the performance of the above described embodiments can be estimated using a different benchmark.
  • the objective of estimating R is to identify its dominant eigenvectors, or more accurately its dominant P-dimensional eigenspace, for some P ⁇ N .
  • chordal distance d c (y, ⁇ ) ⁇ VV + — VV +
  • is chosen, which is the appropriate distance between two subspaces spanned by the NxP orthonormal matrices (y, v). Since during the exploitation phase the embodiments according to the invention require no feedback from the user equipment, these embodiments have been benchmarked by evaluating the number of bits that would be required to achieve a similar accuracy if a classical feedback scheme based on quantization was used.
  • Table 1 Number of spared bits for the nearest-neighbor interpolation for three
  • Table 3 Number of spared bits for the self-interpolation for t iree Riemannian metrics with uplink and downlink frequencies respectively equal to 1.8 GHz and 1.9 GHz (Random Geometry of antennas)
  • Table 4 Number of spared bits for the kernel interpolation for three Riemannian metrics with uplink and downlink frequencies respectively equal to 1.8GHz and 1 .9GHz (Random Geometry of antennas)
  • C(K,N) represents the complexity of the Riemannian gradient descent used for the computation of the barycenter for the affine invariant metric. Since this is an iterative algorithm, this complexity is difficult to evaluate as it depends on the required accuracy. However, it can be reduced by choosing a good initialization, such as the covariance estimated shortly before for the same user
  • Embodiments of the invention provide, amongst others, for the following advantages. Embodiments of the invention allow obtaining information about the covariance matrices or CSI without continuous feedback, as no feedback is required during the exploitation phase. Embodiments of the invention are valid for any antenna array configuration and do not depend on a physical or statistical modelling of user equipments. Embodiments of the invention are independent of the considered uplink and downlink frequencies.
  • Embodiments of the invention exploit reciprocity in the FDD mode.
  • the devices described herein may be implemented as a circuit within a chip or an integrated circuit or an application specific integrated circuit (ASIC).
  • ASIC application specific integrated circuit
  • the invention can be implemented in digital and/or analogue electronic and circuitry.

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

Abstract

L'invention concerne une station de base (100) configurée pour communiquer avec au moins un équipement d'utilisateur (105a-g). La station de base (100) comprend : un réseau d'antennes (101a) comprenant une pluralité d'antennes configurée pour établir un canal de communication en duplex avec ledit au moins un équipement d'utilisateur (105a-g), le canal de communication en duplex étant associé à une paire de matrices de corrélation comprenant une matrice de corrélation de liaison descendante Ri décrivant l'état de canal dans la direction de liaison descendante et une matrice de corrélation de liaison montante Ri UL décrivant l'état de canal dans la direction de liaison montante ; et un processeur (103) configuré pour générer, dans une phase d'apprentissage, pour une pluralité de positions dudit au moins un équipement d'utilisateur (105a-g) ou une pluralité de fois, une pluralité de paires de matrices de corrélation (Ri, Ri UL), le processeur (103) étant configuré pour déterminer chaque matrice de corrélation de liaison montante Ri UL de la pluralité de paires de matrice de corrélation (Ri, Ri UL) à partir d'un signal d'apprentissage de liaison montante respectif reçu dudit au moins un équipement d'utilisateur (105a-g) et pour associer chaque matrice de corrélation de liaison montante Ri UL à une matrice de corrélation de liaison descendante correspondante Ri ; et, dans une phase d'exploitation, déterminer une autre matrice de corrélation liaison montante Rj UL à partir d'un autre signal d'apprentissage de liaison montante reçu dudit au moins un équipement d'utilisateur (105a-g) et estimer une autre matrice de corrélation de liaison descendante Rj correspondant à ladite autre matrice de corrélation de liaison montante Rj UL à partir de ladite autre matrice de corrélation de liaison montante Rj UL et de la pluralité de paires de matrices de corrélation (Ri, Ri UL).
PCT/EP2015/064883 2015-06-30 2015-06-30 Station de base et procédé d'exploitation d'une station de base WO2017000995A1 (fr)

Priority Applications (2)

Application Number Priority Date Filing Date Title
PCT/EP2015/064883 WO2017000995A1 (fr) 2015-06-30 2015-06-30 Station de base et procédé d'exploitation d'une station de base
CN201580080228.9A CN107646172B (zh) 2015-06-30 2015-06-30 基站和操作基站的方法

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EP2207292A1 (fr) * 2007-11-09 2010-07-14 Sumitomo Electric Industries, Ltd. Dispositif de communication radio pour communication par système ofdma
US20120027140A1 (en) * 2010-07-29 2012-02-02 Jianfeng Weng System and method for channel estimation
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EP2207292A1 (fr) * 2007-11-09 2010-07-14 Sumitomo Electric Industries, Ltd. Dispositif de communication radio pour communication par système ofdma
US20120027140A1 (en) * 2010-07-29 2012-02-02 Jianfeng Weng System and method for channel estimation
EP2819313A1 (fr) * 2012-02-23 2014-12-31 Electronics and Telecommunications Research Institute Procédé de communication à entrées multiples et sorties multiples dans un système d'antenne à grande échelle

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