WO2015033661A1 - 通信制御装置、通信制御方法及び端末装置 - Google Patents
通信制御装置、通信制御方法及び端末装置 Download PDFInfo
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- WO2015033661A1 WO2015033661A1 PCT/JP2014/068091 JP2014068091W WO2015033661A1 WO 2015033661 A1 WO2015033661 A1 WO 2015033661A1 JP 2014068091 W JP2014068091 W JP 2014068091W WO 2015033661 A1 WO2015033661 A1 WO 2015033661A1
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- weighting factors
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- communication control
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- 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
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- 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
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- 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
- H04B7/0479—Special codebook structures directed to feedback optimisation for multi-dimensional arrays, e.g. horizontal or vertical pre-distortion matrix index [PMI]
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- 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
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- 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
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04W—WIRELESS COMMUNICATION NETWORKS
- H04W16/00—Network planning, e.g. coverage or traffic planning tools; Network deployment, e.g. resource partitioning or cells structures
- H04W16/24—Cell structures
- H04W16/28—Cell structures using beam steering
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- 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
- H04B7/0695—Hybrid systems, i.e. switching and simultaneous transmission using beam selection
Definitions
- the present disclosure relates to a communication control device, a communication control method, and a terminal device.
- a beam in a desired direction is formed by multiplying the signal of each antenna element by a weighting factor.
- a terminal device selects a recommended set from a set of weighting factors (that is, a precoding matrix) included in a codebook and notifies the base station.
- the base station calculates a set of weighting factors based on the reference signal transmitted by the terminal device.
- Patent Document 1 discloses a technique that uses a combination of a first type of precoding weight and a second type of precoding weight.
- the base station may have a larger number of antenna elements (for example, about 100 antenna elements). It is expected that such a large number of antenna elements can form a sharp beam. Furthermore, it is possible to form a beam in a desired three-dimensional direction by arranging the antenna elements on a plane.
- the load related to beam forming can be increased as the number of antenna elements included in the base station is increased.
- the number of weighting factors also increases, so the processing for calculating a set of weighting factors increases. That is, the load in terms of processing of the terminal device or the base station increases.
- the size of the codebook increases, requiring more radio resources for notification of the recommended set of weighting factors, resulting in increased overhead. That is, the load in terms of radio resources increases.
- the number of antenna elements increases, the number of reference signals increases, so that more radio resources are required for transmitting the reference signals, resulting in an increase in overhead. That is, the load in terms of radio resources increases.
- a weight for forming a beam to a terminal device for each of two or more antenna groups each including a part of a plurality of antenna elements included in a directional antenna capable of forming a three-dimensional beam An acquisition unit for acquiring a set of coefficients, and a plurality of antenna elements for forming a three-dimensional beam to the terminal device based on the set of the weighting coefficients for the two or more antenna groups;
- a communication control device is provided that includes a determination unit that determines a set of weighting factors.
- a beam to a terminal device for each of two or more antenna groups each including a part of a plurality of antenna elements included in a directional antenna capable of forming a three-dimensional beam.
- a plurality of antenna elements for obtaining a set of weighting factors and forming a three-dimensional beam to the terminal device based on the set of weighting factors for the two or more antenna groups Determining a set of weighting factors.
- a determination unit that determines a recommended set of weighting factors for forming a beam to the terminal device, and the recommended set for each of the two or more antenna groups is notified.
- the recommended set for the two or more antenna groups is information used to determine a set of weighting factors for the plurality of antenna elements for forming a three-dimensional beam to the terminal device.
- the present disclosure it is possible to reduce a load related to beam forming.
- the above effects are not necessarily limited, and any of the effects shown in the present specification or other effects that can be grasped from the present specification are exhibited together with or in place of the above effects. May be.
- substantially the same elements may be distinguished by adding different alphabets after the same reference numerals.
- substantially the same elements are distinguished as necessary, such as the three-dimensional beam 20A and the three-dimensional beam 20B.
- the same reference numerals are given.
- the three-dimensional beam 20A and the three-dimensional beam 20B they are simply referred to as the three-dimensional beam 20.
- 8-layer MIMO can be realized in the case of SU-MIMO (Single-User Multiple-Input and Multiple-Output).
- 8-layer MIMO is a technique for spatially multiplexing eight independent streams.
- two layers of MU-MIMO can be realized for four users.
- the half-width of the beam formed by the antennas is expected to be narrow. That is, it is expected that a sharp beam can be formed. Furthermore, by arranging the antenna elements on a plane, it becomes possible to form a beam in a desired three-dimensional direction. It has been proposed to transmit a signal toward a specific building located higher than the base station with such a three-dimensional beam.
- the number of antennas increases, the number of users in MU-MIMO can be increased.
- the number of antennas of the terminal device is two, the number of spatially independent streams for one terminal device is two, and therefore, the MU ⁇ is larger than the number of streams for one terminal device. It is more reasonable to increase the number of MIMO users. For these reasons, it is expected that beam forming will be advanced in LTE downlink.
- FIG. 1 is an explanatory diagram for explaining the relationship between the position of each antenna element and the three-dimensional direction of the beam.
- antenna elements arranged in a lattice shape are shown. Also shown are two axes z, y orthogonal to the plane on which the antenna element is arranged, and one axis x orthogonal to the plane.
- the direction of the beam to be formed is represented by, for example, an angle phi (Greek letter) and an angle theta (Greek letter).
- the angle phi (Greek letter) is an angle formed between the x-axis component and the xy plane component in the beam direction.
- the angle theta is an angle formed between the beam direction and the xy plane (for example, an angle formed between the beam direction and the horizontal plane when the xy plane is parallel to the horizontal plane).
- the weighting factor V m, n of the antenna element arranged m-th in the z-axis direction and n-th in the y-axis direction can be expressed as follows.
- f is the frequency and c is the speed of light.
- J is an imaginary unit in a complex number.
- dv is the distance between the antenna elements in the z-axis direction
- d H is the distance between the antenna elements in the y-axis direction.
- the weighting factor of each antenna element can be obtained by the above-described formula based on the direction and the frequency f. Such weighting factors are used as shown in FIG. 2, for example.
- FIG. 2 is an explanatory diagram for explaining an example of a method of using a weighting factor for beam forming.
- the transmission signal 93 corresponding to each antenna element 91 is complex multiplied by the weighting factor 95 of each antenna element 91.
- the transmission signal in which the weight coefficient 95 is complex-multiplied is transmitted from the antenna element 91.
- complex multiplication of the weighting factor 95 is performed on the digital signal.
- the weight coefficient calculation method is not limited to this. Various calculation techniques can be applied.
- Beam forming in LTE is roughly classified into a method using precoding based on a codebook and a method using precoding not based on a codebook.
- a closed loop method and an open loop method as a method using precoding based on a code book.
- the base station transmits a unique reference signal (for example, CRS (Cell-Specific Reference Signal)) from each of up to four antennas, for example.
- CRS Cell-Specific Reference Signal
- the terminal apparatus estimates channel characteristics by measuring CRS according to the number of transmission antennas of the base station, and calculates an optimal set of weighting factors (precoding matrix) so that the signal quality satisfies a predetermined condition. For example, the terminal apparatus calculates the precoding matrix so that the SINR (Signal to Interference and Noise power Ratio) of the received signal is maximized.
- SINR Signal to Interference and Noise power Ratio
- the terminal device selects a precoding matrix closest to the optimal precoding matrix from the precoding matrix candidates in the codebook and notifies the base station To do.
- a specific example of the code book will be described with reference to FIG.
- FIG. 3 is an explanatory diagram for explaining an example of a code book in which a precoding matrix is defined.
- a codebook including four precoding matrix candidates when the number of layers is 1 and four precoding matrix candidates when the number of layers is two is illustrated.
- the codebook is defined in 3GPP TS 36.211 Table 6.3.4.2.2.3-1.
- the number of rows and the number of columns of each matrix in the codebook are based on the number of transmission antennas and the number of layers (number of data streams), respectively.
- the terminal apparatus determines an optimum precoding matrix candidate from four precoding matrix candidates having one layer number, and notifies the determined precoding matrix candidate to the base station as a recommended precoding matrix.
- the recommended precoding matrix is notified by notifying a codebook index corresponding to the recommended precoding matrix.
- the base station transmits data addressed to the terminal device using the notified recommended precoding matrix (closed loop technique).
- the base station notifies the terminal device of the codebook index corresponding to the precoding matrix to be used (open loop method).
- the recommended precoding matrix can be said to be a recommended set of weighting factors.
- the codebook index is also called, for example, PMI (Precoding Matrix Indicator).
- the codebook when the number of antennas is 4 is defined in 3GPP TS36.211 Table 6.3.4.2.2.3-2.
- a codebook for CSI reporting for a CSI (Channel State Information) reference signal when the number of antennas is 8 is specified in Table 7.2.4-1 of TS36.213 of 3GPP.
- Beamforming with up to 8 layers corresponds to a method using precoding not based on codebook.
- the terminal device does not determine and notify the recommended precoding matrix, and the base station can use any precoding matrix.
- the terminal device transmits a reference signal (sounding reference signal) unique to the terminal device on the uplink. Then, the base station estimates a channel matrix according to reception of the sounding reference signal, and calculates an optimal precoding matrix.
- a reference signal sounding reference signal
- the frequency band in which the sounding reference signal is transmitted is different from the frequency band in which the downlink signal is transmitted by beamforming. Therefore, it is difficult to apply the above method to a precoding matrix for forming a sharp beam.
- FIG. 4 is an explanatory diagram for explaining an example of a signal flow for single-layer beamforming.
- a modulated codeword and a UE (User Equipment) specific reference signal (UE) are mapped to resource elements and transmitted by eight antenna elements.
- a beam is formed by multiplication of such weighting factors.
- FIG. 5 is an explanatory diagram for explaining an example of a signal flow for dual layer beamforming.
- a precoding stage for transmission in a dual layer first stage
- a precoding stage for beamforming second stage
- antenna mounting technology may enable a base station to have a larger number of antenna elements (for example, about 100 antenna elements). It is expected that such a large number of antenna elements can form a sharp beam. Furthermore, it is possible to form a beam in a desired three-dimensional direction by arranging the antenna elements on a plane.
- the load related to beam forming may also increase.
- the number of weighting factors also increases, so the processing for calculating a set of weighting factors increases. That is, the load in terms of processing of the terminal device or the base station increases.
- the size of the codebook increases, requiring more radio resources for notification of the recommended set of weighting factors, resulting in increased overhead. That is, the load in terms of radio resources increases.
- the number of antenna elements increases, the number of reference signals increases, so that more radio resources are required for transmitting the reference signals, resulting in an increase in overhead. That is, the load in terms of radio resources increases.
- the embodiment of the present disclosure makes it possible to reduce the load related to beamforming.
- FIG. 6 is an explanatory diagram illustrating an example of a schematic configuration of the communication system 1 according to the embodiment of the present disclosure.
- the communication system 1 includes a base station 100 and a terminal device 200.
- the base station 100 performs wireless communication with the terminal device 200.
- the base station 100 performs wireless communication with the terminal device 200 located in the cell 10.
- the terminal device 200 performs wireless communication with the base station 100 when located in the cell 10.
- the base station 100 includes a directional antenna that can form a beam in a three-dimensional direction (hereinafter referred to as a “three-dimensional beam”), and transmits a signal using the three-dimensional beam.
- the base station 100 determines a set of three-dimensional beam weighting factors for each terminal device 200, and uses the determined set of weighting factors to transmit a signal addressed to the terminal device 200 using the three-dimensional beam. Then, the terminal device 200 receives the signal transmitted by the three-dimensional beam.
- a three-dimensional beam formed by the base station 100 and an example of signal transmission / reception using the three-dimensional beam will be described with reference to FIGS. 7 and 8.
- FIG. 7 is an explanatory diagram for explaining an example of a three-dimensional beam formed by the base station 100.
- a directional antenna 101 is shown.
- the directional antenna 101 can form a three-dimensional beam.
- the directional antenna 101 forms a plurality of three-dimensional beams 20 in different three-dimensional directions.
- the directional antenna 101 is disposed at a high position, and the three-dimensional beam 20 is radiated downward.
- a communication area 30 corresponding to each three-dimensional beam 20 is generated.
- the three-dimensional beam 20A is formed, and a communication area 30A corresponding to the three-dimensional beam 20A is generated.
- the three-dimensional beam 20B is formed, and a communication area 30B corresponding to the three-dimensional beam 20B is generated.
- FIG. 8 is an explanatory diagram for explaining an example of signal transmission / reception using a three-dimensional beam.
- a base station 100, a terminal device 200A, and a terminal device 200B are shown.
- a three-dimensional beam 20A formed by the base station 100 and a corresponding communication area 30A, and a three-dimensional beam 20B formed by the base station 100 and a corresponding communication area 30B are shown.
- the three-dimensional beam 20A carries a signal to the communication area 30A. That is, the terminal device 200A can receive a signal transmitted from the base station 100 using the three-dimensional beam 20A in the communication area 30A.
- the three-dimensional beam 20B carries a signal to the communication area 30B.
- the terminal device 200B can receive a signal transmitted by the base station 100 using the three-dimensional beam 20B in the communication area 30B.
- the signal intensity of the signal transmitted by the three-dimensional beam 20A is large in the communication area 30A, but small enough to be ignored in the communication area 30B.
- the signal intensity of the signal transmitted by the three-dimensional beam 20B is large in the communication area 30B, but small enough to be ignored in the communication area 30A.
- the base station 100 may transmit a signal with no directivity.
- the base station 100 may form a sector beam and transmit a signal using the sector beam.
- FIG. 9 is a block diagram illustrating an exemplary configuration of the base station 100 according to the embodiment of the present disclosure.
- the base station 100 includes an antenna unit 110, a wireless communication unit 120, a network communication unit 130, a storage unit 140, and a processing unit 150.
- the antenna unit 110 radiates the signal output from the wireless communication unit 120 to the space as a radio wave. Further, the antenna unit 110 converts radio waves in space into a signal and outputs the signal to the wireless communication unit 120.
- the antenna unit 110 forms a three-dimensional beam in a three-dimensional direction and transmits a signal using the three-dimensional beam.
- the antenna unit 110 forms a plurality of three-dimensional beams in different three-dimensional directions.
- the three-dimensional direction of the three-dimensional beam formed by the antenna unit 110 is determined according to a set of weighting factors corresponding to the antenna elements. For example, the processing unit 150 (transmission control unit 151) multiplies the weight coefficient for the signal for each antenna element. As a result, the antenna unit 110 forms a three-dimensional beam in a three-dimensional direction determined according to the weighting factor.
- the antenna unit 110 may transmit a signal with no directivity.
- the antenna unit 110 may form a sector beam and transmit a signal using the sector beam.
- the antenna unit 110 includes, for example, a directional antenna 101 that can form a beam in a three-dimensional direction.
- the antenna unit 110 may further include an omnidirectional antenna or a sector antenna.
- the wireless communication unit 120 performs wireless communication. For example, the radio communication unit 120 transmits a downlink signal to the terminal device 200 located in the cell 10 and receives an uplink signal from the terminal device 200 located in the cell 10.
- Network communication unit 130 The network communication unit 130 communicates with other communication nodes. For example, the network communication unit 130 communicates with other base stations 100 or core network nodes.
- the storage unit 140 stores a program and data for the operation of the base station 100.
- the processing unit 150 provides various functions of the base station 100.
- the processing unit 150 includes a transmission control unit 151, an information acquisition unit 153, and a weight determination unit 155.
- the transmission control unit 151 controls transmission by the base station 100.
- the transmission control unit 151 uses each of two or more antenna groups each including a part of a plurality of antenna elements included in the directional antenna 101 capable of forming a three-dimensional beam. Controls the transmission of reference signals.
- the two or more antenna groups include, for example, a first antenna group including at least two antenna elements arranged in a first direction, and at least two antenna elements arranged in a second direction different from the first direction. And a second antenna group.
- the plurality of antenna elements are antenna elements arranged along a plane parallel to the first direction and the second direction, for example.
- first direction and the second direction are orthogonal to each other.
- the second direction is, for example, a direction parallel to the horizontal plane.
- the base station 100 is controlled by the transmission control unit 151 by using the first antenna group including at least two antenna elements arranged in the first direction which is the vertical direction (or approximately the vertical direction).
- the reference signal is transmitted.
- the base station 100 transmits the reference signal by the second antenna group including at least two antenna elements arranged in the second direction which is the horizontal direction under the control of the transmission control unit 151.
- FIG. 10 is an explanatory diagram for explaining an example of the first antenna group.
- a directional antenna 101 is shown.
- the directional antenna 101 includes a plurality of antenna elements 103. More specifically, in this example, in the directional antenna 101, eight antenna elements 103 are arranged in the first direction 41 that is the vertical direction (or approximately the vertical direction), and the second direction 43 that is the horizontal direction. Eight antenna elements 103 are arranged. That is, in the directional antenna 101, 64 antenna elements 103 are arranged along a plane parallel to the first direction 41 and the second direction 43.
- the first antenna group 105 includes eight antenna elements arranged in the first direction 41 out of the 64 antenna elements 103 included in the directional antenna 101.
- the base station 100 transmits the reference signal through the first antenna group 105 under the control of the transmission control unit 151.
- FIG. 11 is an explanatory diagram for explaining an example of the second antenna group.
- a directional antenna 101 and 64 antenna elements 103 are shown as in FIG.
- the first antenna group 107 includes eight antenna elements arranged in the second direction 43 among the 64 antenna elements 103 included in the directional antenna 101.
- the base station 100 transmits the reference signal through the second antenna group 107 under the control of the transmission control unit 151.
- the base station 100 transmits a reference signal by each antenna group.
- the terminal device 200 can estimate the channel characteristics according to reception of the reference signal transmitted by each antenna group.
- the terminal apparatus 200 can calculate a set of weighting factors for forming a beam to the terminal apparatus 200 by each antenna group based on the estimated channel characteristics.
- each of the two or more antenna groups (for example, the first antenna group and the second antenna group) transmits a reference signal without multiplying a set of weighting factors. That is, each of the two or more antenna groups transmits a reference signal using an omnidirectional beam.
- the transmission control unit 151 controls the transmission of the reference signal by mapping the reference signal to the resource element, generating a signal to be transmitted by each antenna element, and the like.
- the transmission control unit 151 uses each of the two or more antenna groups so that the two or more antenna groups transmit reference signals using different resource blocks. Controls the transmission of reference signals. For example, the transmission control unit 151 controls the transmission of the reference signal so that the first antenna group and the second antenna group transmit the reference signal using different resource blocks.
- the transmission control unit 151 may transmit the reference signal using the resource blocks at different times within the frequency band of at least one of the bandwidths, so that the two or more antenna groups transmit the reference signal. Control transmission of reference signals by each of the antenna groups. For example, under the control of the transmission control unit 151, the first antenna group and the second antenna group receive reference signals in resource blocks of different subframes within a frequency band (12 subcarrier bands) for one resource block. Send.
- the transmission control unit 151 includes the two or more antennas so that the two or more antenna groups transmit reference signals using resource blocks in different frequency bands within at least one time. Control transmission of reference signals by each of the groups. For example, under the control of the transmission control unit 151, the first antenna group and the second antenna group transmit the reference signal in resource blocks of different frequency bands (with different 12 subcarriers) within the same subframe. .
- the first antenna group and the second antenna group are alternately arranged in subframes visited in a predetermined cycle within a frequency band of one resource block by control by the transmission control unit 151.
- Send a reference signal the control by the transmission control unit 151 causes the first antenna group and the second antenna group to transmit reference signals alternately in resource blocks arranged in the frequency direction within one subframe.
- FIG. 12 is an explanatory diagram for explaining an example of a resource block in which a reference signal is transmitted by the first antenna group and the second antenna group.
- the first antenna group transmits a reference signal using resource blocks 55A, 55C, 55E, 55H, 55J, and 55L.
- the second antenna group transmits a reference signal using resource blocks 55B, 55D, 55F, 55G, 55I, 55K, and the like.
- the first antenna group and the second antenna group transmit reference signals alternately in subframes that visit at a predetermined period 53.
- the first antenna group transmits a reference signal in the resource block 55A
- the second antenna group transmits a reference signal in the resource block 55G after a predetermined period 53.
- the second antenna group transmits a reference signal in the resource block 55D
- the first antenna group transmits a reference signal in the resource block 55J after a predetermined period 53.
- the first antenna group and the second antenna group transmit reference signals alternately in resource blocks arranged in the frequency direction. For example, in a certain subframe, the first antenna group transmits a reference signal using resource blocks 55A, 55C, and 55E, and the second antenna group transmits a reference signal using resource blocks 55B, 55D, and 55F. Send. In another subframe, the first antenna group transmits a reference signal using resource blocks 55H, 55J, and 55L, and the second antenna group transmits a reference signal using resource blocks 55G, 55I, and 55K. Send.
- the two or more antenna groups transmit reference signals using different resource blocks.
- a reference signal transmitted in a resource block will be described with reference to FIG.
- FIG. 13 is an explanatory diagram for describing an example of a reference signal transmitted in a resource block.
- two resource blocks 55 are shown.
- the two resource blocks 55 are located in the band 61 of 12 subframes in the frequency direction, and are located in the subframe 63 in the time direction.
- each of the first antenna group and the second antenna group includes eight antenna elements and transmits eight types of reference signals RS 0 to RS 7 . More specifically, for example, the first antenna element included in the antenna group (the first antenna group or the second antenna group) transmits the reference signal RS 0 using the corresponding resource element 65A. Further, the fifth antenna element included in the antenna group, it transmits a reference signal RS 4 in the corresponding resource element 65B.
- each of the two or more antenna groups (for example, the first antenna group and the second antenna group) transmits a reference signal using a different resource block.
- the amount of radio resources used for transmission of reference signals by the two or more antenna groups can be reduced.
- a reference signal is transmitted with resource blocks at different times within a frequency band of any bandwidth.
- the terminal device 200 can perform channel estimation in the same frequency band or a close frequency band for two or more antenna groups.
- the reference signal is transmitted in a resource block of a different frequency band within any time.
- the terminal device 200 can quickly perform channel estimation without waiting for any of two or more antenna groups.
- information regarding a reference signal for beam forming is notified to the terminal device 200 by the base station 100.
- the information includes, for example, a signal sequence transmitted as a reference signal, a predetermined cycle in which the reference signal is transmitted, a subframe offset, and the like.
- the transmission control unit 151 notifies the terminal device 200 of the information via the wireless communication unit 120.
- the mode of the terminal device 200 is changed from an RRC (Radio Resource Control) idle mode to an RRC connection mode, the information is notified to the terminal device 200.
- RRC Radio Resource Control
- the transmission control unit 151 controls transmission of signals to the terminal device 200 by the plurality of antenna elements included in the directional antenna 101.
- the weight determination unit 155 determines a set of weight coefficients for the plurality of antenna elements for forming a three-dimensional beam to the terminal device 200. Then, the transmission control unit 151 controls transmission of a signal to the terminal device 200 by a three-dimensional beam using the determined set of weighting factors. That is, the signal to the terminal device 200 is multiplied by the determined set of weighting factors, and as a result, the signal to the terminal device 200 is transmitted by the three-dimensional beam to the terminal device 200.
- the transmission control unit 151 performs signal mapping to the resource element, multiplication of a weighting factor for each antenna element, generation of a signal to be transmitted for each antenna element, and the like, thereby transmitting a signal to the terminal device 200. Control transmission of
- the information acquisition unit 153 forms a beam to the terminal device 200 for each of two or more antenna groups each including a part of a plurality of antenna elements included in the directional antenna 101 capable of forming a three-dimensional beam. Get a set of weighting factors.
- the information acquisition unit 153 acquires the set of weighting factors for forming a beam to the terminal device 200 for the first antenna group. Further, the information acquisition unit 153 acquires the set of weighting factors for forming a beam to the terminal device 200 for the second antenna group.
- the information acquisition unit 153 acquires, for example, a recommended set of weighting factors notified by the terminal device 200 as the set of weighting factors.
- the terminal device 200 estimates channel characteristics according to reception of a reference signal transmitted by each antenna group. Then, the terminal device 200 determines a recommended set of weighting factors for forming a beam to the terminal device 200 for each antenna group based on the estimated channel characteristics, and notifies the base station 100 of the recommended set. To do. Then, the information acquisition unit 153 acquires the recommended set.
- the base station 100 can acquire a set of weighting factors for forming a beam to the terminal device 200 for each antenna group.
- the notification of the recommended set is, for example, a notification of an index indicating one of a plurality of recommended set candidates for weighting factors. That is, the terminal device 200 notifies the recommended set to be determined by notifying an index indicating the determined recommended set among the plurality of recommended set candidates.
- an index notification for example, overhead can be suppressed.
- the plurality of recommended set candidates are sets of weighting factors included in the codebook.
- the index is a codebook index of the codebook.
- the same codebook is stored in the base station 100 (storage unit 140) and the terminal device 200. Then, the terminal device 200 notifies the recommended set of weighting factors by notifying the codebook index. Then, the base station 100 acquires a recommended set of weighting factors from the codebook index using the codebook.
- the codebook index can also be referred to as PMI, for example.
- the codebook index can be notified to the base station 100 as a part (PMI) of channel state information (CSI).
- the notification of the recommended set for the antenna group is performed, for example, in a subframe that is four subframes after the subframe in which the reference signal is transmitted by the antenna group.
- the weight determination unit 155 sets the weighting factors for the plurality of antenna elements to form a three-dimensional beam to the terminal device 200 based on the set of the weighting factors for the two or more antenna groups. To decide.
- the information acquisition unit 153 acquires a set of weighting factors for forming a beam to the terminal device 200 for each of the first antenna group and the second antenna group. Then, the weight determining unit 155 is configured to determine the plurality of antenna elements based on the set of the weighting factors for the first antenna group and the set of the weighting factors for the second antenna group. A set of weighting factors for forming a three-dimensional beam to the terminal device 200 is determined.
- the first antenna group 105 and the second antenna group 107 each include eight antenna elements 103. Then, the weight determination unit 155 sets the weighting factors for the 64 antenna elements 103 based on the weighting factor set for the first antenna group 105 and the weighting factor set for the second antenna group 107. To decide.
- the weight determination unit 155 performs multiplication of a matrix indicating a set of weighting factors for the first antenna group and a matrix indicating a set of weighting factors for the second antenna group. Determining the set of weighting factors for the plurality of antenna elements.
- the first antenna group 105 includes antenna elements arranged in the first direction 41 (that is, the vertical direction), and the second antenna group 107 includes the second antenna group 107.
- M for example, eight
- N for example, eight
- the precoding matrix W y of the first antenna group 105, the precoding matrix W x for the second antenna group 107 are obtained.
- the weight coefficient W i, j of the antenna element arranged i-th in the first direction and j-th arranged in the second direction is calculated as follows, for example.
- the weight coefficient W i, j calculated in this way is a weight coefficient for the plurality of antenna elements (for example, 64 antenna elements) for forming a three-dimensional beam to the terminal device 200. Determined as a set.
- the method for calculating and determining the set of the weighting factors for the plurality of antenna elements is not limited to the above-described example. For example, various calculation and determination techniques can be applied depending on the preconditions such as the arrangement of antenna elements, the setting of antenna groups, or the number of antenna groups.
- a set of weighting factors for the plurality of antenna elements for forming a three-dimensional beam to the terminal device 200 is determined. Thereby, it is possible to reduce the load related to beam forming.
- a set of weighting factors for a smaller number of antenna elements may be calculated for each antenna group. The processing load required can be reduced.
- the reference signal instead of transmitting the reference signal by a large number of antenna elements, it is only necessary to transmit the reference signal by a smaller number of antenna elements for each antenna group, so there is an overhead for transmitting the reference signal. May decrease. For example, in this way, the load related to beamforming can be reduced from the viewpoint of processing or radio resources.
- FIG. 14 is a block diagram illustrating an exemplary configuration of the terminal device 200 according to an embodiment of the present disclosure.
- the terminal device 200 includes an antenna unit 210, a wireless communication unit 220, a storage unit 230, an input unit 240, a display unit 250, and a processing unit 260.
- the antenna unit 210 radiates the signal output from the wireless communication unit 220 to the space as a radio wave. Further, the antenna unit 210 converts a radio wave in the space into a signal and outputs the signal to the wireless communication unit 220.
- the wireless communication unit 220 performs wireless communication. For example, when the terminal device 200 is located in the cell 10, the radio communication unit 220 receives a downlink signal from the base station 100 and transmits an uplink signal to the base station 100.
- the storage unit 230 stores a program and data for the operation of the terminal device 200.
- the input unit 240 receives input from the user of the terminal device 200. Then, the input unit 240 provides the input result to the processing unit 260.
- Display unit 250 The display unit 250 displays a screen for showing to the user of the terminal device 200. For example, the display unit 250 displays the screen according to control by the processing unit 260 (display control unit 265).
- the processing unit 260 provides various functions of the terminal device 200.
- the processing unit 260 includes an estimated weight determination unit 261, a notification unit 263, and a display control unit 265.
- the estimated weight determination unit 261 determines a set of weight coefficients. For example, the estimated weight determination unit 261 determines a recommended set of weighting factors.
- the estimated weight determination unit 261 forms a beam to the terminal device 200 for each of the two or more antenna groups in response to reception of the reference signal transmitted by each of the two or more antenna groups. Determine a recommended set of weighting factors for.
- the estimated weight determination unit 261 determines channel characteristics (for example, according to reception of a reference signal transmitted by each antenna group (for example, each of the first antenna group and the second antenna group)). Channel matrix). Then, the estimated weight determining unit 261 determines a recommended set of weighting factors for forming a beam to the terminal device 200 based on the estimated channel characteristics for each antenna group.
- the estimated weight determining unit 261 calculates an optimal precoding matrix (that is, a set of weighting factors) that maximizes the SINR based on the estimated channel matrix. Then, the estimated weight determination unit 261 selects a precoding matrix closest to the optimal precoding matrix from the precoding matrices included in the codebook, and recommends the selected precoding matrix (that is, the recommended precoding matrix). As a recommended set of weighting factors).
- the estimated weight determination unit 261 selects a precoding matrix having a minimum distance metric to the optimal precoding matrix among the precoding matrices included in the codebook as the precoding matrix closest to the optimal precoding matrix.
- the distance metric D L between the L-th precoding matrix W L and the optimal precoding matrix V in the codebook is the (i, j) -th element V i, j of the optimal precoding matrix V, precoding matrix W L (i, j) th element W L, i, with j, is expressed as follows.
- a recommended set of weighting factors for each of the two or more antenna groups is determined.
- the notification unit 263 notifies the base station 100 of information.
- the notification unit 263 notifies the recommended set for each of the two or more antenna groups.
- the estimated weight determination unit 261 determines a recommended set of weighting factors for forming a beam to the terminal device 200 for each of the two or more antenna groups. Then, the notification unit 263 notifies the base station 100 of the determined recommended set via the wireless communication unit 220.
- the notification unit 263 notifies the recommended set to be determined by notifying an index indicating the determined recommended set of the plurality of recommended set candidates.
- an index notification for example, overhead can be suppressed.
- the plurality of recommended set candidates are sets of weighting factors included in the codebook.
- the index is a codebook index of the codebook.
- the same codebook is stored in the base station 100 and the terminal device 200 (storage unit 230). Then, the terminal device 200 notifies the recommended set by notifying the codebook index indicating the determined recommended set.
- the codebook index can also be referred to as PMI, for example.
- the notification unit 263 notifies the codebook index as a part of CSI (PMI).
- the recommended set for the two or more antenna groups is used to determine the set of weighting factors for the plurality of antenna elements for forming a three-dimensional beam to the terminal device 200. Information used.
- the display control unit 265 controls display of the output screen by the display unit 250. For example, the display control unit 265 generates an output screen displayed by the display unit 250 and causes the display unit 250 to display the output screen.
- FIG. 15 is a sequence diagram illustrating an example of a schematic flow of the entire communication control process according to the embodiment of the present disclosure.
- the base station 100 makes a report request for a CSI report (S401).
- the base station 100 transmits a reference signal using the first antenna group (S403).
- the terminal device 200 estimates channel characteristics (channel matrix) for the first antenna group (S405). Then, the terminal device 200 determines a recommended set of weighting factors for the first antenna group based on the estimated channel characteristics (S407).
- the recommended set to be determined is a set of weighting factors for forming a beam to the terminal device 200 by the first antenna group.
- the terminal device 200 notifies the base station 100 of a codebook index (codebook index for the first antenna group) indicating the determined recommended set (S409). For example, the terminal device 200 notifies the codebook index in a subframe that is four subframes after the subframe in which the reference signal is transmitted.
- the base station 100 transmits a reference signal using the second antenna group (S411).
- the terminal device 200 estimates channel characteristics (channel matrix) for the second antenna group (S413). Then, the terminal device 200 determines a recommended set of weighting factors for the second antenna group based on the estimated channel characteristics (S415).
- the recommended set to be determined is a set of weighting factors for forming a beam to the terminal device 200 by the second antenna group.
- the terminal device 200 notifies the base station 100 of a codebook index (codebook index for the second antenna group) indicating the determined recommended set (S417). For example, the terminal device 200 notifies the codebook index in a subframe that is four subframes after the subframe in which the reference signal is transmitted.
- the base station 100 determines a plurality of antenna elements included in the directional antenna 101 based on the recommended set of weighting factors for the first antenna group and the recommended set of weighting factors for the second antenna group.
- a set of weighting factors is determined (S419).
- the set of weighting factors to be determined is a set of weighting factors for forming a three-dimensional beam to the terminal device 200 by the plurality of antenna elements.
- steps S403 to S409 and steps S411 to S417 may be interchanged in the time direction, or may be partially or entirely overlapped.
- FIG. 16 is a flowchart illustrating an example of a schematic flow of the communication control processing on the base station side according to the embodiment of the present disclosure.
- the communication control process is a process related to transmission of a reference signal.
- the base station 100 notifies the terminal device 200 of information related to a reference signal for beamforming (S431).
- the base station 100 transmits a reference signal for each antenna group in accordance with control by the transmission control unit 151 (S433). Thereafter, when a predetermined period for transmitting the reference signal comes (S435: Yes), the reference signal is transmitted again (S433). In this way, the transmission of the reference signal is repeated at a predetermined cycle.
- the base station 100 transmits a reference signal by each of the two or more antenna groups. Then, the base station 100 acquires a recommended set of weighting factors notified by the terminal device 200 for each antenna group as the set of weighting factors for forming a beam to the terminal device 200. That is, the above-described exemplary embodiment employs a scheme that uses precoding based on a codebook.
- the base station 100 uses, for each antenna group, a set of weighting factors calculated according to reception of the reference signal transmitted by the terminal device 200 to the beam to the terminal device 200. Is obtained as the above set of weighting factors to form That is, the first modification employs a scheme that uses precoding that is not based on a codebook.
- Base station 100 transmission control unit 151
- the transmission control unit 151 does not need to control transmission of the reference signal by each of the two or more antenna groups, or controls the transmission. It does not have to be. That is, the base station 100 may transmit the reference signal by each of the two or more antenna groups, or may not transmit the reference signal.
- the information acquisition unit 153 sends a set of weighting factors calculated in response to reception of the reference signal transmitted by the terminal device 200 to the terminal device 200. Acquired as a set of weighting factors to form the beam.
- the terminal device 200 transmits a sounding reference signal.
- the base station 100 estimates channel characteristics according to reception of the sounding reference signal by each of the two or more antenna groups (for example, the first antenna group and the second antenna group). To do.
- the base station 100 sets, for each of the two or more antenna groups, an optimal set of weighting factors that maximizes the SIRN based on the estimated channel characteristics (that is, the optimal Precoding matrix) is calculated.
- the information acquisition unit 153 acquires, for each antenna group group, an optimal set of weighting factors calculated as described above as a set of weighting factors for forming a beam to the terminal device 200.
- a method using precoding that is not based on a codebook may be employed.
- the base station 100 can acquire a set of weighting factors for forming a beam to the terminal device 200 for each antenna group.
- the recommended set of weighting factors may be notified by the terminal device 200.
- the information acquisition unit 153 may acquire the notified recommended set as the set of weighting factors. That is, a method using precoding based on a code book may be employed.
- the terminal device 200 may not notify the recommended set of weighting factors. In this case, the information acquisition unit 153 may not acquire the notified recommended set as the set of weighting factors.
- the estimated weight determination unit 261 may determine a recommended set of weighting factors for forming a beam to the terminal device 200 for each of the two or more antenna groups, and a notification unit 263 may notify the recommended set.
- the estimated weight determination unit 261 may not determine a recommended set of weighting factors for forming a beam to the terminal device 200 for each of the two or more antenna groups. The notification unit 263 may not notify the recommended set.
- FIG. 17 is a sequence diagram illustrating an example of a schematic flow of the entire communication control process according to the first modification.
- the terminal device 200 transmits a reference signal (sounding reference signal) (S501).
- the base station 100 estimates channel characteristics (channel matrix) for the first antenna group (S503). Also, the base station 100 estimates channel characteristics (channel matrix) for the second antenna group (S505).
- the base station 100 calculates a set of weighting factors for the first antenna group based on the estimated channel characteristics for the first antenna group (S507).
- the base station 100 calculates a set of weighting factors for the second antenna group based on the estimated channel characteristics for the second antenna group (S509).
- Each set of calculated weighting factors is a set of weighting factors for forming a beam to the terminal device 200.
- the base station 100 determines a plurality of antenna elements included in the directional antenna 101 based on the set of weighting factors for the first antenna group and the set of weighting factors for the second antenna group.
- a set of weighting factors is determined (S511).
- the set of weighting factors to be determined is a set of weighting factors for forming a three-dimensional beam to the terminal device 200 by the plurality of antenna elements.
- the terminal device 200 forms the three-dimensional beam to the terminal device 200 based on the set of the weighting factors for the two or more antenna groups.
- a set of weighting factors for a plurality of antenna elements is determined.
- the estimated weight determination unit 261 determines a set of weight coefficients. For example, the estimated weight determination unit 261 determines a recommended set of weighting factors.
- the estimated weight determination unit 261 acquires a set of weighting factors for forming a beam to the terminal device 200 for each of the two or more antenna groups. Then, the estimated weight determination unit 261 uses the weights for the plurality of antenna elements to form a three-dimensional beam to the terminal device 200 based on the set of the weight coefficients for the two or more antenna groups. Determine a set of coefficients. For example, the estimated weight determination unit 261 determines the set of weighting factors as a recommended set of weighting factors.
- the estimated weight determination unit 261 responds to reception of a reference signal transmitted by each of the two or more antenna groups (for example, the first antenna group and the second antenna group). Estimate channel characteristics (eg, channel matrix). Then, the estimated weight determining unit 261 calculates a set of weighting factors for forming a beam to the terminal device 200 for each of the two or more antenna groups based on the estimated channel characteristics. Furthermore, the estimated weight determination unit 261 uses the weights for the plurality of antenna elements to form a three-dimensional beam to the terminal device 200 based on the set of the weighting factors for the two or more antenna groups. Determine a set of coefficients. The estimated weight determination unit 261 determines, for example, the set of weight coefficients as a recommended set of weight coefficients.
- the notification unit 263 notifies a recommended set of weighting factors for the plurality of antenna elements for forming a three-dimensional beam to the terminal device 200.
- the notification unit 263 notifies the set of the weighting factors for the plurality of antenna elements by notifying an index (codebook index) indicating the recommended set.
- the information acquisition unit 153 acquires a set of weight coefficients for the plurality of antenna elements for forming a three-dimensional beam to the terminal device 200.
- the terminal device 200 notifies the base station 100 of a recommended set of weighting factors for the plurality of antenna elements for forming a three-dimensional beam to the terminal device 200. Then, the information acquisition unit 153 acquires the recommended set.
- the information acquisition unit 153 does not need to acquire a set of weighting factors for forming a beam to the terminal device 200 for each of the two or more antenna groups.
- the weight determination unit 155 finally determines a set of weighting factors for the plurality of antenna elements for forming a three-dimensional beam to the terminal device 200.
- the weight determination unit 155 finally determines the recommended set of weighting factors acquired by the information acquisition unit 153 as the set of weighting factors for the plurality of antenna elements. Note that the weight determination unit 155 determines another set of weighting factors different from the recommended set based on the recommended set of weighting factors acquired by the information acquisition unit 153 and sets the weighting factors for the plurality of antenna elements. You may finally determine as said set.
- FIG. 18 is a sequence diagram illustrating an example of a schematic flow of the entire communication control process according to the second modification.
- the base station 100 makes a report request for a CSI report (S531).
- the base station 100 transmits a reference signal using the first antenna group (S533).
- the terminal device 200 estimates channel characteristics (channel matrix) for the first antenna group (S535). Then, the terminal device 200 calculates a set of weighting factors for the first antenna group based on the estimated channel characteristics (S537).
- the set of weighting factors to be calculated is a set of weighting factors for forming a beam to the terminal device 200 by the first antenna group.
- the base station 100 transmits a reference signal using the second antenna group (S541).
- the terminal device 200 estimates channel characteristics (channel matrix) for the second antenna group (S543). Then, the terminal device 200 calculates a set of weighting factors for the second antenna group based on the estimated channel characteristics (S545).
- the set of weighting factors to be calculated is a set of weighting factors for forming a beam to the terminal device 200 by the second antenna group.
- the terminal device 200 weights the plurality of antenna elements included in the directional antenna 101 based on the set of weighting factors for the first antenna group and the set of weighting factors for the second antenna group.
- a set of coefficients is determined (S547).
- the set of weighting factors is determined as a recommended set of weighting factors.
- the terminal device 200 notifies the base station 100 of a codebook index (codebook index for a plurality of antenna elements included in the directional antenna 101) indicating the determined recommended set (S549).
- the base station 100 finally determines a set of weighting factors for the plurality of antenna elements based on the recommended set of weighting factors for the plurality of antenna elements included in the directional antenna 101 ( S551).
- the communication control device having the technical features according to the embodiment of the present disclosure is not the device of the base station 100 but the terminal device 200. That is, the terminal device 200 acquires a set of weighting factors for each of the two or more antenna groups, and determines a set of weighting factors for the plurality of antenna elements based on the set of the weighting factors.
- the base station 100 determines that the weighting factor of the at least one antenna group is greater when the angle is outside the predetermined angle range than when the angle is within the predetermined angle range.
- a set of weighting factors for forming a beam having weaker directivity is acquired.
- the base station 100 determines the weighting factor for a plurality of antenna elements for forming a beam (three-dimensional beam, two-dimensional beam, or omnidirectional beam). Determine the set.
- the base station 100 determines a set of weighting factors for a plurality of antenna elements for forming a three-dimensional beam.
- Base station 100 Information acquisition unit 153
- the information acquisition unit 153 is within the angle range. Instead, for at least one antenna group, a set of weighting factors for forming a beam having weaker directivity is obtained as the set of weighting factors.
- the first antenna group 105 includes antenna elements 103 arranged in the first direction 41.
- the first direction 41 is a vertical direction.
- the terminal device 200 estimates channel characteristics according to reception of a reference signal transmitted by the first antenna group 105. Then, the terminal device 200 calculates an angle formed by the radiation direction of the beam to the terminal device 200 by the first antenna group 105 and the horizontal plane from the estimated channel characteristics. For example, the angle is within a predetermined angle range (for example, a range from ⁇ A to A).
- the terminal apparatus 200 uses a weighting factor for forming a beam to the terminal apparatus 200 for each of the first antenna group 105 and the second antenna group 107, as in the example of the embodiment described above. Determine a recommended set of On the other hand, for example, the angle is outside the predetermined angle range. In this case, the terminal device 200 sets a set of weighting factors for forming a beam having weaker directivity as the recommended set for at least one of the first antenna group 105 and the second antenna group 107. decide. Then, the terminal device 200 notifies the base station 100 of the recommended set.
- the information acquisition unit 153 forms a beam to the terminal device 200 using the recommended set of weighting factors notified by the terminal device 200 for each of the first antenna group 105 and the second antenna group 107.
- the base station 100 forms a beam having weaker directivity for at least one of the first antenna group 105 and the second antenna group 107 when the angle is out of the predetermined angle range. Get a set of weighting factors for.
- a specific example will be described with reference to FIG.
- FIG. 19 is an explanatory diagram for explaining an example of the weighting coefficient acquired according to the angle for the antenna group.
- angles theta 1, theta 2 and theta 3 formed by the radiation directions of the beams to the terminal device 200A, the terminal device 200B, and the terminal device 200C and the horizontal plane are shown.
- theta 1 and theta 2 are outside a predetermined angular range (for example, a range of ⁇ A or more and A or less). Therefore, for terminal device 200A and terminal device 200B, a set of weighting factors for forming a beam having weak directivity is acquired as a set of weighting factors for the first antenna group.
- a three-dimensional beam is not formed for the terminal device 200A and the terminal device 200B.
- theta 3 is within a predetermined angle range. Therefore, for terminal apparatus 200C, a set of weighting factors for forming a beam having strong directivity is acquired as a set of weighting factors for the first antenna group. As a result, a three-dimensional beam is formed for the terminal device 200C.
- An angle theta (Greek letter) between the radiation direction of the beam to the terminal device 200 by the first antenna group and the horizontal plane is the weight coefficient V m of the m-th antenna element in the first direction 41 (vertical direction), and It can be calculated using the distance d between the antenna elements in the first direction 41 (vertical direction).
- the weighting factor V m is the angle theta, the distance d, using the frequency f, the speed of light c, since is expressed by the following formula, and the formula, the weighting factor V
- the angle theta can be calculated using m , the distance d, the frequency f, and the speed of light c.
- the third modification is not limited to this example. Whether or not the angle between the radiation direction of the beam to the terminal device 200 and the horizontal plane is within a predetermined angle range is determined by, for example, the angle between the radiation direction of the beam to the terminal device 200 and the vertical direction being different. It may be performed by determining whether or not it is within the predetermined range. As described above, whether or not the angle between the radiation direction of the beam to the terminal device 200 and the horizontal plane is within the predetermined angle range does not need to be determined using the angle itself, and is substantially determined. Just do it.
- the weight determination unit 155 determines a set of weight coefficients for the plurality of antenna elements for forming a three-dimensional beam to the terminal device 200. That is, when the angle is within the predetermined angle range, a set of weighting factors for forming a three-dimensional beam is determined.
- the weight determination unit 155 determines a set of weighting factors for the plurality of antenna elements for forming a beam to the terminal device 200. That is, when the angle is outside the predetermined angle range, the set of weighting factors to be determined is not limited to the set of weighting factors for forming a three-dimensional beam. It can be a set of weighting factors for forming the beam.
- a terminal device 200 that does not require a three-dimensional beam uses a beam having weaker directivity, and a terminal device 200 that requires a three-dimensional beam It becomes possible to use a three-dimensional beam.
- a three-dimensional beam can be used for the terminal device 200 located at the cell edge or the terminal device 200 assumed to be located on the upper floor of a building. Thereby, in the communication system, it is possible to reduce the processing load while improving the communication quality.
- the estimated weight determining unit 261 when the angle formed between the radiation direction of the beam to the terminal device 200 and the horizontal plane is outside a predetermined angle range, the angle is within the angle range.
- the set of weighting factors for forming a beam having weaker directivity is determined as a recommended set of weighting factors for at least one antenna group.
- the estimated weight determination unit 261 estimates the channel characteristics in response to reception of the reference signal transmitted by the first antenna group 105, and the beam to the terminal device 200 from the estimated channel characteristics.
- the angle formed between the radiation direction and the horizontal plane is calculated.
- the angle is within a predetermined angle range.
- the estimated weight determination unit 261 forms a beam to the terminal device 200 for each of the first antenna group 105 and the second antenna group 107 as in the example of the embodiment described above. Determine a recommended set of weighting factors.
- the angle is outside the predetermined angle range.
- the estimated weight determining unit 261 sets a set of weighting factors for forming a beam having weaker directivity as the recommended set for at least one of the first antenna group and the second antenna group. decide. Then, the recommended set is notified to the base station 100 by the notification unit 263.
- FIG. 20 is a sequence diagram illustrating an example of a schematic flow of the entire communication control process according to the third modification.
- the base station 100 makes a CSI report request (S601).
- the base station 100 transmits a reference signal using the first antenna group (S603).
- the terminal device 200 estimates channel characteristics (channel matrix) for the first antenna group (S605). Then, the terminal device 200 calculates the angle formed by the radiation direction of the beam to the terminal device 200 by the first antenna group and the horizontal plane from the estimated channel characteristics (S607). Furthermore, the terminal device 200 determines a recommended set of weighting factors for the first antenna group based on the estimated channel characteristics (S609). For example, when the angle is out of a predetermined angle range, the terminal device 200 determines a set of weighting factors for forming a beam having weaker directivity as the recommended set.
- the terminal device 200 notifies the base station 100 of a codebook index (codebook index for the first antenna group) indicating the determined recommended set (S611). For example, the terminal device 200 notifies the codebook index in a subframe that is four subframes after the subframe in which the reference signal is transmitted.
- the base station 100 transmits a reference signal using the second antenna group (S613).
- the terminal device 200 estimates channel characteristics (channel matrix) for the second antenna group (S615). Then, the terminal device 200 determines a recommended set of weighting factors for the second antenna group based on the estimated channel characteristics (S617). For example, when the angle is out of a predetermined angle range, the terminal device 200 determines a set of weighting factors for forming a beam having weaker directivity as the recommended set.
- the terminal device 200 notifies the base station 100 of a codebook index (codebook index for the second antenna group) indicating the determined recommended set (S619). For example, the terminal device 200 notifies the codebook index in a subframe that is four subframes after the subframe in which the reference signal is transmitted.
- the base station 100 determines a plurality of antenna elements included in the directional antenna 101 based on the recommended set of weighting factors for the first antenna group and the recommended set of weighting factors for the second antenna group.
- a set of weighting factors is determined (S621).
- the set of weighting factors to be determined is a set of weighting factors for forming a beam (for example, a three-dimensional beam, a two-dimensional beam, or an omnidirectional beam) to the terminal device 200 by the plurality of antenna elements. .
- the terminal device 200 may notify the base station of a recommended set of weighting factors for each antenna group without considering whether the angle is within a predetermined angle range. Then, when the angle is outside the predetermined angle range, the base station 100 may acquire a weighting factor having weaker directivity for at least one antenna group instead of the recommended set to be notified. .
- the terminal device 200 may transmit a reference signal, and the base station 100 may estimate channel characteristics in response to reception of the reference signal. And base station 100 may acquire a weighting factor which has weak directivity about at least one antenna group, when the above-mentioned angle is outside a predetermined angle range.
- the number of antenna elements that form the beam to the terminal device 200 changes according to the angle between the radiation direction of the beam to the terminal device 200 and the horizontal plane.
- the base station 100 determines a set of weighting factors for a plurality of antenna elements included in the directional antenna 101 when the angle is within a predetermined angle range. On the other hand, the base station 100 determines a set of weighting factors for antenna elements that are fewer than a plurality of antenna elements included in the directional antenna 101 when the angle is outside the predetermined angle range.
- Base station 100 Information acquisition unit 153
- the information acquisition unit 153 for each of the two or more antenna groups, when the angle formed between the radiation direction of the beam to the terminal device 200 and the horizontal plane is within a predetermined angle range, A set of weighting factors for forming a beam to the terminal device 200 is acquired.
- the information acquisition unit 153 forms the plurality of beams for forming the beam to the terminal device 200.
- a set of weighting factors is obtained for fewer antenna elements.
- the terminal device 200 estimates channel characteristics according to reception of a reference signal transmitted by the first antenna group 105. Then, the terminal device 200 calculates an angle formed by the radiation direction of the beam to the terminal device 200 by the first antenna group 105 and the horizontal plane from the estimated channel characteristics. For example, the angle is within a predetermined angle range (for example, a range from ⁇ A to A). In this case, the terminal apparatus 200 uses a weighting factor for forming a beam to the terminal apparatus 200 for each of the first antenna group 105 and the second antenna group 107, as in the example of the embodiment described above. Determine a recommended set of On the other hand, for example, the angle is outside the predetermined angle range.
- a predetermined angle range for example, a range from ⁇ A to A
- the terminal device 200 uses fewer antenna elements than the plurality of antenna elements included in the directional antenna 101. Determine a recommended set of weighting factors. As an example, a recommended set of weighting factors is determined for 4 (2 ⁇ 2) or 16 (4 ⁇ 4) antenna elements, which is less than 64 (8 ⁇ 8) antenna elements. Then, the terminal device 200 notifies the base station 100 of the recommended set. And the information acquisition part 153 acquires the recommended set notified. If the angle is within the predetermined angle range, the information acquisition unit 153 acquires a recommended set for the first antenna group 105 and the second antenna group 107, and the angle is outside the predetermined angle range. If so, get a recommended set for fewer antenna elements.
- the angle calculation method and the method for determining whether or not the angle is within the predetermined angle range are as described in connection with the third modification.
- Base station 100 Weight determining unit 1555
- the weight determination unit 155 determines a set of weighting factors for the plurality of antenna elements based on the set of the weighting factors for the two or more antenna groups. .
- the weight determination unit 155 determines a set of weighting factors for antenna elements that are fewer than the plurality of antenna elements for forming a beam to the terminal device 200.
- the information acquisition unit 153 acquires a recommended set for fewer antenna elements if the angle is outside the predetermined angle range. Then, the weight determination unit 155 determines the recommended set for fewer antenna elements as a set of weight coefficients for forming a beam to the terminal device 200. As an example, a set of weighting factors is determined for 4 (2 ⁇ 2) or 16 (4 ⁇ 4) antenna elements, less than 64 (8 ⁇ 8) antenna elements. Then, a signal is transmitted to the terminal device 200 with fewer antenna elements than the above.
- the terminal device 200 that does not require a three-dimensional beam uses a beam having weaker directivity, and the terminal device 200 that requires a three-dimensional beam It becomes possible to use a three-dimensional beam.
- a three-dimensional beam can be used for the terminal device 200 located at the cell edge or the terminal device 200 assumed to be located on the upper floor of a building.
- the number of antenna elements used for signal transmission to the terminal device 200 is reduced, it is possible to reduce the processing load. Also, for example, since a recommended set of weighting factors for fewer antenna elements (ie, a set of weighting factors in a smaller codebook) is notified, the amount of codebook index information (eg, the number of bits) decreases. . Therefore, overhead can be suppressed.
- the estimated weight determining unit 261 determines a recommended set of weighting factors for forming a beam to the terminal device 200 for each of the two or more antenna groups.
- the estimated weight determining unit 261 determines a recommended set of weighting factors for forming a beam to the terminal device 200 for the antenna elements that are smaller than the plurality of antenna elements.
- the estimated weight determination unit 261 estimates the channel characteristics in response to reception of the reference signal transmitted by the first antenna group 105, and the beam to the terminal device 200 from the estimated channel characteristics.
- the angle formed between the radiation direction and the horizontal plane is calculated.
- the angle is within a predetermined angle range.
- the estimated weight determination unit 261 forms a beam to the terminal device 200 for each of the first antenna group 105 and the second antenna group 107 as in the example of the embodiment described above. Determine a recommended set of weighting factors.
- the angle is outside the predetermined angle range.
- the estimated weight determination unit 261 instead of determining a recommended set for the first antenna group 105 and the second antenna group 107, the estimated weight determination unit 261 has fewer antennas than the plurality of antenna elements included in the directional antenna 101. Determine a recommended set of weighting factors for the element. As an example, a recommended set of weighting factors is determined for 4 (2 ⁇ 2) or 16 (4 ⁇ 4) antenna elements, which is less than 64 (8 ⁇ 8) antenna elements. Then, the recommended set is notified to the base station 100 by the notification unit 263.
- FIG. 21 is a sequence diagram showing a first example of a schematic flow of the entire communication control process according to the fourth modification.
- the said 1st example is an example in case the angle which the radiation direction of the beam to the terminal device 200 and the horizontal plane make is in a predetermined angle range.
- the base station 100 makes a report request for a CSI report (S641).
- the base station 100 transmits a reference signal using the first antenna group (S643).
- the terminal device 200 estimates channel characteristics (channel matrix) for the first antenna group (S645). Then, the terminal device 200 calculates the angle formed by the radiation direction of the beam to the terminal device 200 by the first antenna group and the horizontal plane from the estimated channel characteristics (S647). In this example, since the angle is within a predetermined angle range, the terminal device 200 determines a recommended set of weighting factors for the first antenna group based on the estimated channel characteristics (S649).
- the terminal device 200 notifies the base station 100 of a codebook index (codebook index for the first antenna group) indicating the determined recommended set (S651). For example, the terminal device 200 notifies the codebook index in a subframe that is four subframes after the subframe in which the reference signal is transmitted.
- the base station 100 transmits a reference signal using the second antenna group (S653).
- the terminal device 200 estimates channel characteristics (channel matrix) for the second antenna group (S655). In this example, since the angle is within a predetermined angle range, the terminal device 200 determines a recommended set of weighting factors for the second antenna group based on the estimated channel characteristics (S657).
- the terminal device 200 notifies the base station 100 of a codebook index (codebook index for the second antenna group) indicating the determined recommended set (S659). For example, the terminal device 200 notifies the codebook index in a subframe that is four subframes after the subframe in which the reference signal is transmitted.
- the base station 100 determines a plurality of antenna elements included in the directional antenna 101 based on the recommended set of weighting factors for the first antenna group and the recommended set of weighting factors for the second antenna group.
- a set of weighting factors is determined (S661).
- the set of weighting factors to be determined is a set of weighting factors for forming a three-dimensional beam to the terminal device 200 by the plurality of antenna elements.
- FIG. 22 is a sequence diagram showing a second example of a schematic flow of the entire communication control process according to the fourth modification.
- the second example is an example in a case where the angle formed between the radiation direction of the beam to the terminal device 200 and the horizontal plane is outside a predetermined angle range.
- the base station 100 makes a CSI report request (S671).
- the base station 100 transmits a reference signal using the first antenna group (S673).
- the terminal device 200 estimates channel characteristics (channel matrix) for the first antenna group (S675). Then, the terminal device 200 calculates the angle formed by the radiation direction of the beam to the terminal device 200 by the first antenna group and the horizontal plane from the estimated channel characteristics (S677). In this example, the angle is outside the predetermined angle range.
- the base station 100 transmits a reference signal using the second antenna group (S681).
- the terminal device 200 estimates channel characteristics (channel matrix) for the second antenna group (S683).
- the terminal device 200 determines a recommended set of weighting factors for the antenna elements that are fewer than the plurality of antenna elements included in the directional antenna 101 (S685). ).
- the terminal device 200 notifies the base station 100 of a codebook index (a codebook index for fewer antenna elements) indicating the determined recommended set (S687).
- the base station 100 determines a set of weighting factors for fewer antenna elements based on the recommended set of weighting factors for fewer antenna elements included in the directional antenna (S689).
- the set of the weighting factors to be determined is a set of weighting factors for forming a beam (for example, a three-dimensional beam, a two-dimensional beam, or an omnidirectional beam) to the terminal device 200 with fewer antenna elements than the above. .
- the 4th modification is not limited to the example which concerns.
- the antenna elements that are fewer than the plurality of antenna elements may be antenna elements included in a part of the two or more antenna groups.
- the terminal device 200 when the angle formed between the radiation direction of the beam to the terminal device 200 by the first antenna group and the horizontal plane is outside a predetermined angle range, the terminal device 200 includes the first antenna group and the second antenna group.
- a recommended set for one of the antenna groups may be determined.
- the base station 100 may determine a set of weighting factors for the one of the first antenna group and the second antenna group based on the recommended set. Good. Thereafter, a signal may be transmitted to the terminal device 200 by the one of the first antenna group and the second antenna group.
- the base station 100 may be realized as any type of eNB (evolved Node B) such as a macro eNB, a pico eNB, or a home eNB.
- the base station 100 may be realized as another type of base station such as a NodeB or a BTS (Base Transceiver Station).
- Base station 100 may include a main body (also referred to as a base station apparatus) that controls radio communication, and one or more RRHs (Remote Radio Heads) that are arranged at locations different from the main body.
- RRHs Remote Radio Heads
- the terminal device 200 is a smartphone, a tablet PC (Personal Computer), a notebook PC, a portable game terminal, a mobile terminal such as a portable / dongle type mobile router or a digital camera, or an in-vehicle terminal such as a car navigation device. It may be realized as.
- the terminal device 200 may be realized as a terminal (also referred to as an MTC (Machine Type Communication) terminal) that performs M2M (Machine To Machine) communication.
- the terminal device 200 may be a wireless communication module (for example, an integrated circuit module configured by one die) mounted on these terminals.
- FIG. 23 is a block diagram illustrating a first example of a schematic configuration of an eNB to which the technology according to the present disclosure may be applied.
- the eNB 800 includes one or more antennas 810 and a base station device 820. Each antenna 810 and the base station apparatus 820 can be connected to each other via an RF cable.
- Each of the antennas 810 has a single or a plurality of antenna elements (for example, a plurality of antenna elements constituting a MIMO antenna), and is used for transmission and reception of radio signals by the base station apparatus 820.
- at least one antenna 810 is a directional antenna capable of forming a three-dimensional beam.
- the eNB 800 includes a plurality of antennas 810 as illustrated in FIG. 23, and the plurality of antennas 810 may respectively correspond to a plurality of frequency bands used by the eNB 800, for example. 23 shows an example in which the eNB 800 includes a plurality of antennas 810, the eNB 800 may include a single antenna 810.
- the base station apparatus 820 includes a controller 821, a memory 822, a network interface 823, and a wireless communication interface 825.
- the controller 821 may be a CPU or a DSP, for example, and operates various functions of the upper layer of the base station apparatus 820. For example, the controller 821 generates a data packet from the data in the signal processed by the wireless communication interface 825, and transfers the generated packet via the network interface 823. The controller 821 may generate a bundled packet by bundling data from a plurality of baseband processors, and may transfer the generated bundled packet. In addition, the controller 821 is a logic that executes control such as radio resource control, radio bearer control, mobility management, inflow control, or scheduling. May have a typical function. Moreover, the said control may be performed in cooperation with a surrounding eNB or a core network node.
- the memory 822 includes RAM and ROM, and stores programs executed by the controller 821 and various control data (for example, terminal list, transmission power data, scheduling data, and the like).
- the network interface 823 is a communication interface for connecting the base station device 820 to the core network 824.
- the controller 821 may communicate with the core network node or other eNB via the network interface 823.
- the eNB 800 and the core network node or another eNB may be connected to each other by a logical interface (for example, an S1 interface or an X2 interface).
- the network interface 823 may be a wired communication interface or a wireless communication interface for wireless backhaul.
- the network interface 823 may use a frequency band higher than the frequency band used by the wireless communication interface 825 for wireless communication.
- the wireless communication interface 825 supports any cellular communication scheme such as LTE (Long Term Evolution) or LTE-Advanced, and provides a wireless connection to terminals located in the cell of the eNB 800 via the antenna 810.
- the wireless communication interface 825 may typically include a baseband (BB) processor 826, an RF circuit 827, and the like.
- the BB processor 826 may perform, for example, encoding / decoding, modulation / demodulation, and multiplexing / demultiplexing, and each layer (for example, L1, MAC (Medium Access Control), RLC (Radio Link Control), and PDCP).
- Various signal processing of Packet Data Convergence Protocol
- Packet Data Convergence Protocol is executed.
- the BB processor 826 may have some or all of the logical functions described above instead of the controller 821.
- the BB processor 826 may be a module that includes a memory that stores a communication control program, a processor that executes the program, and related circuits. The function of the BB processor 826 may be changed by updating the program. Good.
- the module may be a card or a blade inserted into a slot of the base station apparatus 820, or a chip mounted on the card or the blade.
- the RF circuit 827 may include a mixer, a filter, an amplifier, and the like, and transmits and receives a radio signal via the antenna 810.
- the wireless communication interface 825 includes a plurality of BB processors 826 as illustrated in FIG. 23, and the plurality of BB processors 826 may respectively correspond to a plurality of frequency bands used by the eNB 800, for example. Further, the wireless communication interface 825 includes a plurality of RF circuits 827 as shown in FIG. 23, and the plurality of RF circuits 827 may respectively correspond to a plurality of antenna elements, for example. 23 shows an example in which the wireless communication interface 825 includes a plurality of BB processors 826 and a plurality of RF circuits 827, the wireless communication interface 825 includes a single BB processor 826 or a single RF circuit 827. But you can.
- FIG. 24 is a block diagram illustrating a second example of a schematic configuration of an eNB to which the technology according to the present disclosure may be applied.
- the eNB 830 includes one or more antennas 840, a base station apparatus 850, and an RRH 860. Each antenna 840 and RRH 860 may be connected to each other via an RF cable. Base station apparatus 850 and RRH 860 can be connected to each other via a high-speed line such as an optical fiber cable.
- Each of the antennas 840 has a single or a plurality of antenna elements (for example, a plurality of antenna elements constituting a MIMO antenna), and is used for transmission / reception of radio signals by the RRH 860.
- the at least one antenna 840 is a directional antenna capable of forming a three-dimensional beam.
- the eNB 830 includes a plurality of antennas 840 as illustrated in FIG. 24, and the plurality of antennas 840 may respectively correspond to a plurality of frequency bands used by the eNB 830, for example. 24 shows an example in which the eNB 830 has a plurality of antennas 840, but the eNB 830 may have a single antenna 840.
- the base station device 850 includes a controller 851, a memory 852, a network interface 853, a wireless communication interface 855, and a connection interface 857.
- the controller 851, the memory 852, and the network interface 853 are the same as the controller 821, the memory 822, and the network interface 823 described with reference to FIG.
- the wireless communication interface 855 supports a cellular communication method such as LTE or LTE-Advanced, and provides a wireless connection to a terminal located in a sector corresponding to the RRH 860 via the RRH 860 and the antenna 840.
- the wireless communication interface 855 may typically include a BB processor 856 and the like.
- the BB processor 856 is the same as the BB processor 826 described with reference to FIG. 23 except that the BB processor 856 is connected to the RF circuit 864 of the RRH 860 via the connection interface 857.
- the wireless communication interface 855 includes a plurality of BB processors 856 as illustrated in FIG.
- the plurality of BB processors 856 may respectively correspond to a plurality of frequency bands used by the eNB 830, for example.
- 24 shows an example in which the wireless communication interface 855 includes a plurality of BB processors 856, the wireless communication interface 855 may include a single BB processor 856.
- connection interface 857 is an interface for connecting the base station device 850 (wireless communication interface 855) to the RRH 860.
- the connection interface 857 may be a communication module for communication on the high-speed line that connects the base station apparatus 850 (wireless communication interface 855) and the RRH 860.
- the RRH 860 includes a connection interface 861 and a wireless communication interface 863.
- connection interface 861 is an interface for connecting the RRH 860 (wireless communication interface 863) to the base station device 850.
- the connection interface 861 may be a communication module for communication on the high-speed line.
- the wireless communication interface 863 transmits and receives wireless signals via the antenna 840.
- the wireless communication interface 863 may typically include an RF circuit 864 and the like.
- the RF circuit 864 may include a mixer, a filter, an amplifier, and the like, and transmits and receives a radio signal via the antenna 840.
- the wireless communication interface 863 includes a plurality of RF circuits 864 as illustrated in FIG. 24, and the plurality of RF circuits 864 may correspond to, for example, a plurality of antenna elements, respectively. 24 shows an example in which the wireless communication interface 863 includes a plurality of RF circuits 864, the wireless communication interface 863 may include a single RF circuit 864.
- the transmission control unit 151, the information acquisition unit 153, and the weight determination unit 155 described with reference to FIG. 9 include the radio communication interface 825, the radio communication interface 855, and / or the radio
- the communication interface 863 may be implemented. Further, at least a part of these functions may be implemented in the controller 821 and the controller 851.
- FIG. 25 is a block diagram illustrating an example of a schematic configuration of a smartphone 900 to which the technology according to the present disclosure can be applied.
- the smartphone 900 includes a processor 901, a memory 902, a storage 903, an external connection interface 904, a camera 906, a sensor 907, a microphone 908, an input device 909, a display device 910, a speaker 911, a wireless communication interface 912, one or more antenna switches 915.
- One or more antennas 916, a bus 917, a battery 918 and an auxiliary controller 919 are provided.
- the processor 901 may be, for example, a CPU or a SoC (System on Chip), and controls the functions of the application layer and other layers of the smartphone 900.
- the memory 902 includes a RAM and a ROM, and stores programs executed by the processor 901 and data.
- the storage 903 can include a storage medium such as a semiconductor memory or a hard disk.
- the external connection interface 904 is an interface for connecting an external device such as a memory card or a USB (Universal Serial Bus) device to the smartphone 900.
- the camera 906 includes, for example, an image sensor such as a CCD (Charge Coupled Device) or a CMOS (Complementary Metal Oxide Semiconductor), and generates a captured image.
- the sensor 907 may include a sensor group such as a positioning sensor, a gyro sensor, a geomagnetic sensor, and an acceleration sensor.
- the microphone 908 converts sound input to the smartphone 900 into an audio signal.
- the input device 909 includes, for example, a touch sensor that detects a touch on the screen of the display device 910, a keypad, a keyboard, a button, or a switch, and receives an operation or information input from a user.
- the display device 910 has a screen such as a liquid crystal display (LCD) or an organic light emitting diode (OLED) display, and displays an output image of the smartphone 900.
- the speaker 911 converts an audio signal output from the smartphone 900 into audio.
- the wireless communication interface 912 supports any cellular communication method such as LTE or LTE-Advanced, and performs wireless communication.
- the wireless communication interface 912 may typically include a BB processor 913, an RF circuit 914, and the like.
- the BB processor 913 may perform, for example, encoding / decoding, modulation / demodulation, and multiplexing / demultiplexing, and performs various signal processing for wireless communication.
- the RF circuit 914 may include a mixer, a filter, an amplifier, and the like, and transmits and receives radio signals via the antenna 916.
- the wireless communication interface 912 may be a one-chip module in which the BB processor 913 and the RF circuit 914 are integrated.
- the wireless communication interface 912 may include a plurality of BB processors 913 and a plurality of RF circuits 914 as illustrated in FIG.
- FIG. 25 illustrates an example in which the wireless communication interface 912 includes a plurality of BB processors 913 and a plurality of RF circuits 914.
- the wireless communication interface 912 includes a single BB processor 913 or a single RF circuit 914. But you can.
- the wireless communication interface 912 may support other types of wireless communication methods such as a short-range wireless communication method, a proximity wireless communication method, or a wireless LAN (Local Area Network) method in addition to the cellular communication method.
- a BB processor 913 and an RF circuit 914 for each wireless communication method may be included.
- Each of the antenna switches 915 switches the connection destination of the antenna 916 among a plurality of circuits (for example, circuits for different wireless communication systems) included in the wireless communication interface 912.
- Each of the antennas 916 includes a single or a plurality of antenna elements (for example, a plurality of antenna elements constituting a MIMO antenna), and is used for transmission / reception of a radio signal by the radio communication interface 912.
- the smartphone 900 may include a plurality of antennas 916 as illustrated in FIG. Note that although FIG. 25 illustrates an example in which the smartphone 900 includes a plurality of antennas 916, the smartphone 900 may include a single antenna 916.
- the smartphone 900 may include an antenna 916 for each wireless communication method.
- the antenna switch 915 may be omitted from the configuration of the smartphone 900.
- the bus 917 connects the processor 901, memory 902, storage 903, external connection interface 904, camera 906, sensor 907, microphone 908, input device 909, display device 910, speaker 911, wireless communication interface 912, and auxiliary controller 919 to each other.
- the battery 918 supplies power to each block of the smartphone 900 illustrated in FIG. 25 via a power supply line partially illustrated by a broken line in the drawing.
- the auxiliary controller 919 operates the minimum necessary functions of the smartphone 900 in the sleep mode.
- the recommended weight determination unit 261 and the notification unit 263 described with reference to FIG. 14 may be implemented in the wireless communication interface 912.
- at least a part of these functions may be implemented in the processor 901 or the auxiliary controller 919.
- FIG. 26 is a block diagram illustrating an example of a schematic configuration of a car navigation device 920 to which the technology according to the present disclosure can be applied.
- the car navigation device 920 includes a processor 921, a memory 922, a GPS (Global Positioning System) module 924, a sensor 925, a data interface 926, a content player 927, a storage medium interface 928, an input device 929, a display device 930, a speaker 931, and wireless communication.
- the interface 933 includes one or more antenna switches 936, one or more antennas 937, and a battery 938.
- the processor 921 may be a CPU or SoC, for example, and controls the navigation function and other functions of the car navigation device 920.
- the memory 922 includes RAM and ROM, and stores programs and data executed by the processor 921.
- the GPS module 924 measures the position (for example, latitude, longitude, and altitude) of the car navigation device 920 using GPS signals received from GPS satellites.
- the sensor 925 may include a sensor group such as a gyro sensor, a geomagnetic sensor, and an atmospheric pressure sensor.
- the data interface 926 is connected to the in-vehicle network 941 through a terminal (not shown), for example, and acquires data generated on the vehicle side such as vehicle speed data.
- the content player 927 reproduces content stored in a storage medium (for example, CD or DVD) inserted into the storage medium interface 928.
- the input device 929 includes, for example, a touch sensor, a button, or a switch that detects a touch on the screen of the display device 930, and receives an operation or information input from the user.
- the display device 930 has a screen such as an LCD or an OLED display, and displays a navigation function or an image of content to be reproduced.
- the speaker 931 outputs the navigation function or the audio of the content to be played back.
- the wireless communication interface 933 supports any cellular communication method such as LTE or LTE-Advanced, and performs wireless communication.
- the wireless communication interface 933 may typically include a BB processor 934, an RF circuit 935, and the like.
- the BB processor 934 may perform, for example, encoding / decoding, modulation / demodulation, and multiplexing / demultiplexing, and performs various signal processing for wireless communication.
- the RF circuit 935 may include a mixer, a filter, an amplifier, and the like, and transmits and receives a radio signal via the antenna 937.
- the wireless communication interface 933 may be a one-chip module in which the BB processor 934 and the RF circuit 935 are integrated.
- the wireless communication interface 933 may include a plurality of BB processors 934 and a plurality of RF circuits 935 as shown in FIG. 26 shows an example in which the wireless communication interface 933 includes a plurality of BB processors 934 and a plurality of RF circuits 935, the wireless communication interface 933 includes a single BB processor 934 or a single RF circuit 935. But you can.
- the wireless communication interface 933 may support other types of wireless communication methods such as a short-range wireless communication method, a proximity wireless communication method, or a wireless LAN method in addition to the cellular communication method.
- a BB processor 934 and an RF circuit 935 may be included for each communication method.
- Each of the antenna switches 936 switches the connection destination of the antenna 937 among a plurality of circuits included in the wireless communication interface 933 (for example, circuits for different wireless communication systems).
- Each of the antennas 937 has a single or a plurality of antenna elements (for example, a plurality of antenna elements constituting a MIMO antenna), and is used for transmission / reception of a radio signal by the radio communication interface 933.
- the car navigation device 920 may include a plurality of antennas 937 as shown in FIG. FIG. 26 shows an example in which the car navigation apparatus 920 includes a plurality of antennas 937. However, the car navigation apparatus 920 may include a single antenna 937.
- the car navigation device 920 may include an antenna 937 for each wireless communication method.
- the antenna switch 936 may be omitted from the configuration of the car navigation device 920.
- the battery 938 supplies power to each block of the car navigation device 920 shown in FIG. 26 through a power supply line partially shown by broken lines in the drawing. Further, the battery 938 stores electric power supplied from the vehicle side.
- the recommended weight determination unit 261 and the notification unit 263 described with reference to FIG. 14 may be implemented in the wireless communication interface 933. Further, at least a part of these functions may be implemented in the processor 921.
- the technology according to the present disclosure may be realized as an in-vehicle system (or vehicle) 940 including one or more blocks of the car navigation device 920 described above, an in-vehicle network 941, and a vehicle side module 942.
- vehicle-side module 942 generates vehicle-side data such as vehicle speed, engine speed, or failure information, and outputs the generated data to the in-vehicle network 941.
- the information acquisition unit 153 includes, for each of two or more antenna groups each including a part of a plurality of antenna elements included in the directional antenna 101 that can form a three-dimensional beam.
- a set of weighting factors for forming a beam to the terminal device 200 is acquired.
- the weight determining unit 155 then weights the plurality of antenna elements to form a three-dimensional beam to the terminal device 200 based on the set of the weight coefficients for the two or more antenna groups. Determine the set.
- a set of weighting factors for a smaller number of antenna elements may be calculated for each antenna group.
- the processing load required can be reduced.
- instead of notifying the codebook index of a set of weighting factors of a large number of antenna elements it is only necessary to notify the combination of codebook indexes of a set of weighting factors of a smaller number of antenna elements.
- the overhead for can be reduced.
- instead of transmitting the reference signal by a large number of antenna elements it is only necessary to transmit the reference signal by a smaller number of antenna elements for each antenna group, so there is an overhead for transmitting the reference signal. May decrease. For example, in this way, the load related to beamforming can be reduced from the viewpoint of processing or radio resources.
- the transmission control unit 151 controls the transmission of the reference signal by each of the two or more antenna groups.
- the terminal device 200 can estimate the channel characteristics according to the reception of the reference signal transmitted by each antenna group. Then, the terminal apparatus 200 can calculate a set of weighting factors for forming a beam to the terminal apparatus 200 by each antenna group based on the estimated channel characteristics.
- the transmission control unit 151 may transmit the reference signal using the resource blocks at different times within the frequency band of at least one of the bandwidths, so that the two or more antenna groups transmit the reference signal. Control transmission of reference signals by each of the antenna groups.
- the terminal device 200 can perform channel estimation in the same frequency band or a close frequency band for two or more antenna groups.
- the transmission control unit 151 includes the two or more antennas so that the two or more antenna groups transmit reference signals using resource blocks in different frequency bands within at least one time. Control transmission of reference signals by each of the groups.
- the terminal device 200 can quickly perform channel estimation without waiting for any of two or more antenna groups.
- the information acquisition unit 153 acquires a recommended set of weighting factors notified by the terminal device 200 as the set of weighting factors.
- the base station 100 can acquire a set of weighting factors for forming a beam to the terminal device 200 for each antenna group.
- the notification of the recommended set is, for example, a notification of an index indicating one of a plurality of recommended set candidates for weighting factors.
- the information acquisition unit 153 transmits a set of weighting factors calculated in response to reception of the reference signal transmitted by the terminal device 200 to the beam to the terminal device 200. Is obtained as a set of weighting factors for forming.
- the base station 100 can acquire a set of weighting factors for forming a beam to the terminal device 200 for each antenna group.
- the information acquisition unit 153 includes To form a beam having a weaker directivity as the above set of weighting factors for at least one antenna group than when the angle is outside the predetermined angular range. Get a set of weighting factors. For example, the angle formed by the radiation direction of the beam to the terminal device 200 and the horizontal plane is within the predetermined angle range. In this case, the weight determination unit 155 determines a set of weighting factors for the plurality of antenna elements for forming a three-dimensional beam to the terminal device 200.
- the weight determination unit 155 determines a set of weight coefficients for the plurality of antenna elements for forming a beam to the terminal device 200.
- a terminal device 200 that does not require a three-dimensional beam may use a beam having weaker directivity, and a terminal device 200 that requires a three-dimensional beam may use a three-dimensional beam. It becomes possible.
- a three-dimensional beam can be used for the terminal device 200 located at the cell edge or the terminal device 200 assumed to be located on the upper floor of a building. Thereby, in the communication system, it is possible to reduce the processing load while improving the communication quality.
- the angle formed between the radiation direction of the beam to the terminal device 200 and the horizontal plane is within a predetermined angle range.
- the information acquisition unit 153 acquires a set of weighting factors for forming a beam to the terminal device 200 for each of the two or more antenna groups.
- the weight determining unit 155 determines a set of weighting factors for the plurality of antenna elements based on the set of the weighting factors for the two or more antenna groups.
- the angle formed between the radiation direction of the beam to the terminal device 200 and the horizontal plane is outside the predetermined angle range. In this case, the weight determination unit 155 determines a set of weighting factors for antenna elements that are fewer than the plurality of antenna elements for forming a beam to the terminal device 200.
- a terminal device 200 that does not require a three-dimensional beam may use a beam having weaker directivity, and a terminal device 200 that requires a three-dimensional beam may use a three-dimensional beam. It becomes possible.
- a three-dimensional beam can be used for the terminal device 200 located at the cell edge or the terminal device 200 assumed to be located on the upper floor of a building. Thereby, in the communication system, it is possible to reduce the processing load while improving the communication quality.
- the number of antenna elements used for signal transmission to the terminal device 200 is reduced, it is possible to reduce the processing load. Also, for example, since a recommended set of weighting factors for fewer antenna elements (ie, a set of weighting factors in a smaller codebook) is notified, the amount of codebook index information (eg, the number of bits) decreases. . Therefore, overhead can be suppressed.
- a set of weighting factors related to beamforming has been described.
- a set of weighting factors for transmission in a plurality of layers is separately determined. May be. That is, in addition to the precoding matrix for the second stage precoding, a precoding matrix for the first stage precoding may be separately determined. In this way, even when transmission is performed in a plurality of layers, a precoding matrix (a set of weighting factors) for beamforming can be similarly determined.
- the directional antenna includes a plurality of antenna elements and the set of weighting factors for the plurality of antennas is determined.
- the directional antenna includes one or more antenna elements. Additional antenna elements may be included.
- the said several antenna element demonstrated the example arrange
- the plurality of antenna elements may be arranged in another shape (for example, parallelogram, trapezoid, triangle, circle, etc.).
- processing steps in the communication control processing of this specification do not necessarily have to be executed in time series in the order described in the flowchart.
- the processing steps in the communication control process may be executed in an order different from the order described in the flowchart, or may be executed in parallel.
- a computer for causing a communication control device (base station device or terminal device) and hardware such as a CPU, ROM, and RAM incorporated in the terminal device to exhibit functions equivalent to the respective components of the communication control device.
- Programs can also be created.
- a storage medium storing the computer program may also be provided.
- An information processing apparatus for example, a processing circuit or a chip including a memory (for example, ROM and RAM) for storing the computer program and a processor (for example, CPU) for executing the computer program may be provided.
- a set of weighting factors for forming a beam to the terminal device is acquired.
- a communication control device comprising: (2)
- the two or more antenna groups include a first antenna group including at least two antenna elements arranged in a first direction, and at least two antenna elements arranged in a second direction different from the first direction.
- the communication control device including a second antenna group.
- the determining unit is configured to multiply the matrix for the plurality of antenna elements through multiplication of a matrix indicating a set of weighting factors for the first antenna group and a matrix indicating a set of weighting factors for the second antenna group.
- the communication control device according to (4) or (5), wherein the set of weighting factors is determined.
- the communication control apparatus according to any one of (1) to (6), further including a transmission control unit that controls transmission of a reference signal by each of the two or more antenna groups.
- the communication control apparatus wherein the acquisition unit acquires a recommended set of weighting factors notified by the terminal device as the set of weighting factors.
- the notification of the recommended set is a notification of an index indicating one of a plurality of recommended set candidates of weighting factors.
- the plurality of recommended set candidates are sets of weighting factors included in a codebook;
- the index is a codebook index of the codebook;
- the communication control device according to (9) above.
- the transmission control unit controls transmission of reference signals by each of the two or more antenna groups such that the two or more antenna groups transmit reference signals using different resource blocks.
- the communication control apparatus according to any one of (10).
- the transmission control unit is configured to transmit each of the two or more antenna groups so that the two or more antenna groups transmit reference signals using resource blocks at different times within a frequency band of at least one of the bandwidths.
- the communication control device which controls transmission of a reference signal by the control unit.
- the transmission control unit is configured to transmit a reference signal by each of the two or more antenna groups so that the two or more antenna groups transmit reference signals in resource blocks of different frequency bands within at least one of the times.
- the acquisition unit acquires a set of weighting factors calculated in response to reception of a reference signal transmitted by the terminal device as the set of weighting factors, and any one of (1) to (6) The communication control device according to item.
- the acquisition unit is more than the two or more than when the angle is within the angular range.
- the determining unit determines a set of weighting factors for the plurality of antenna elements to form a three-dimensional beam to the terminal device when the angle is within the predetermined angle range; If the angle is outside the predetermined angle range, determine a set of weighting factors for the plurality of antenna elements to form a beam to the terminal device;
- the communication control apparatus according to any one of (1) to (14).
- the acquisition unit acquires the set of the weighting factors for each of the two or more antenna groups when an angle formed between a radiation direction of a beam to the terminal device and a horizontal plane is within a predetermined angle range.
- the determining unit sets the weighting factor for the plurality of antenna elements based on the set of weighting factors for the two or more antenna groups when the angle is within the predetermined angle range.
- Decide The communication control apparatus according to any one of (1) to (14).
- the determining unit determines a set of weighting factors for antenna elements that are fewer than the plurality of antenna elements for forming a beam to the terminal device when the angle is outside the predetermined angle range.
- the communication control device according to (16).
- a set of weighting factors for forming a beam to the terminal device is acquired. And Determining a set of weighting factors for the plurality of antenna elements to form a three-dimensional beam to the terminal device based on the set of weighting factors for the two or more antenna groups; Including a communication control method.
- a terminal device Two or more antenna groups according to reception of reference signals transmitted by each of two or more antenna groups each including a part of a plurality of antenna elements included in a directional antenna capable of forming a three-dimensional beam
- a determination unit for determining a recommended set of weighting factors for forming a beam to the terminal device for each of
- a notification unit for notifying the recommended set for each of the two or more antenna groups;
- the recommended set for the two or more antenna groups is information used to determine a set of weighting factors for the plurality of antenna elements to form a three-dimensional beam to the terminal device. Terminal device.
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Abstract
Description
端末装置であって、3次元ビームを形成可能な指向性アンテナに含まれる複数のアンテナ素子の一部をそれぞれ含む2つ以上のアンテナグループの各々により送信されるリファレンス信号の受信に応じて、当該2つ以上のアンテナグループの各々について、上記端末装置へのビームを形成するための重み係数の推奨セットを決定する決定部と、上記2つ以上のアンテナグループの各々についての上記推奨セットを通知する通知部と、を備える端末装置が提供される。上記2つ以上のアンテナグループについての上記推奨セットは、上記端末装置への3次元ビームを形成するための上記複数のアンテナ素子についての重み係数のセットを決定するのに使用される情報である。
1.はじめに
2.通信システムの概略的な構成
3.各通信ノードの構成
3.1.基地局の構成
3.2.端末装置の構成
4.処理の流れ
5.変形例
5.1.第1の変形例
5.2.第2の変形例
5.3.第3の変形例
5.4.第4の変形例
6.応用例
6.1.基地局に関する応用例
6.2.端末装置に関する応用例
7.まとめ
まず、図1~図5を参照して、ビームフォーミングに関する動向、ビームフォーミングに関する各種技術、及びビームフォーミングに関する課題を説明する。
近年の移動体データ通信端末の普及により、爆発的に増加するトラフィックへの対応が急務となっている。そのため、3GPP(Third Generation Partnership Project)では、MU-MIMO(Multi-User Multiple-Input and Multiple-Output)、CoMP(Coordinated Multipoint transmission/reception)等の、通信容量を増加させるための技術が検討されている。
ビームフォーミングのための各アンテナ素子の重み係数は、複素数として表される。この点について図1を参照して具体的に説明する。
LTEにおけるビームフォーミングは、コードブックに基づくプリコーディングを使用する方式と、コードブックに基づかないプリコーディングを使用する方式とに大別される。また、コードブックに基づくプリコーディングを使用する方式には、閉ループによる手法と開ループによる手法とがある。
基地局は例えば4本までのアンテナからそれぞれユニークなリファレンス信号(例えば、CRS(Cell-Specific Reference Signal))を送信する。端末装置は、基地局の送信アンテナ本数に応じたCRSを測定することによりチャネル特性を推定し、信号品質が所定の条件を満たすように最適な重み係数のセット(プリコーディング行列)を算出する。例えば、端末装置は、受信信号のSINR(Signal to Interference and Noise power Ratio)が最大になるようにプリコーディング行列を算出する。
レイヤ数が8までのビームフォーミングは、コードブックに基づかないプリコーディングを使用する方式に対応している。当該方式では、端末装置による推奨プリコーディング行列の決定及び通知は行われず、基地局は任意のプリコーディング行列を使用し得る。
図4及び図5を参照して、ビームフォーミングについての信号フローを説明する。
上述したように、近年のアンテナ実装技術の進歩により、基地局がさらに多数のアンテナ素子(例えば、100個程度のアンテナ素子)を有することも可能になり得る。このような多数のアンテナ素子によって鋭いビームの形成が可能になると予想される。さらに、平面にアンテナ素子を配置することにより、所望の3次元方向へのビームを形成することが可能になる。
続いて、図6~図8を参照して、本開示の実施形態に係る通信システム1の概略的な構成を説明する。図6は、本開示の実施形態に係る通信システム1の概略的な構成の一例を示す説明図である。図6を参照すると、通信システム1は、基地局100及び端末装置200を含む。
続いて、図9~図14を参照して、本開示の実施形態に係る基地局100及び端末装置200の構成を説明する。
まず、図9~図13を参照して、本開示の実施形態に係る基地局100の構成の一例を説明する。図9は、本開示の実施形態に係る基地局100の構成の一例を示すブロック図である。図9を参照すると、基地局100は、アンテナ部110、無線通信部120、ネットワーク通信部130、記憶部140及び処理部150を備える。
アンテナ部110は、無線通信部120により出力された信号を電波として空間に放射する。また、アンテナ部110は、空間の電波を信号に変換し、当該信号を無線通信部120へ出力する。
無線通信部120は、無線通信を行う。例えば、無線通信部120は、セル10内に位置する端末装置200へのダウンリンク信号を送信し、セル10内に位置する端末装置200からのアップリンク信号を受信する。
ネットワーク通信部130は、他の通信ノードと通信する。例えば、ネットワーク通信部130は、他の基地局100又はコアネットワークノードと通信する。
記憶部140は、基地局100の動作のためのプログラム及びデータを記憶する。
処理部150は、基地局100の様々な機能を提供する。処理部150は、送信制御部151、情報取得部153及び重み決定部155を含む。
送信制御部151は、基地局100による送信を制御する。
例えば、送信制御部151は、3次元ビームを形成可能な指向性アンテナ101に含まれる複数のアンテナ素子の一部をそれぞれ含む2つ以上のアンテナグループの各々によるリファレンス信号の送信を制御する。
例えば、送信制御部151は、上記2つ以上のアンテナグループが、異なるリソースブロックでリファレンス信号を送信するように、上記2つ以上のアンテナグループの各々によるリファレンス信号の送信を制御する。送信制御部151は、例えば、第1のアンテナグループ及び第2のアンテナグループが、異なるリソースブロックでリファレンス信号を送信するように、リファレンス信号の送信を制御する。
例えば、送信制御部151は、指向性アンテナ101に含まれる上記複数のアンテナ素子による端末装置200への信号の送信を制御する。
情報取得部153は、3次元ビームを形成可能な指向性アンテナ101に含まれる複数のアンテナ素子の一部をそれぞれ含む2つ以上のアンテナグループの各々について、端末装置200へのビームを形成するための重み係数のセットを取得する。
情報取得部153は、例えば、端末装置200により通知される重み係数の推奨セットを、上記重み係数の上記セットとして取得する。
重み決定部155は、上記2つ以上のアンテナグループについての上記重み係数の上記セットに基づいて、端末装置200への3次元ビームを形成するための、上記複数のアンテナ素子についての重み係数のセットを決定する。
次に、図14を参照して、本開示の実施形態に係る端末装置200の構成の一例を説明する。図14は、本開示の実施形態に係る端末装置200の構成の一例を示すブロック図である。図14を参照すると、端末装置200は、アンテナ部210、無線通信部220、記憶部230、入力部240、表示部250及び処理部260を備える。
アンテナ部210は、無線通信部220により出力された信号を電波として空間に放射する。また、アンテナ部210は、空間の電波を信号に変換し、当該信号を無線通信部220へ出力する。
無線通信部220は、無線通信を行う。例えば、無線通信部220は、端末装置200がセル10内に位置する場合に、基地局100からのダウンリンク信号を受信し、基地局100へのアップリンク信号を送信する。
記憶部230は、端末装置200の動作のためのプログラム及びデータを記憶する。
入力部240は、端末装置200のユーザによる入力を受け付ける。そして、入力部240は、入力結果を処理部260に提供する。
表示部250は、端末装置200のユーザに見せるための画面を表示する。例えば、表示部250は、処理部260(表示制御部265)による制御に応じて、上記画面を表示する。
処理部260は、端末装置200の様々な機能を提供する。処理部260は、推定重み決定部261、通知部263及び表示制御部265を含む。
推定重み決定部261は、重み係数のセットを決定する。例えば、推定重み決定部261は、重み係数の推奨セットを決定する。
通知部263は、基地局100に情報を通知する。
表示制御部265は、表示部250による出力画面の表示を制御する。例えば、表示制御部265は、表示部250により表示される出力画面を生成し、当該出力画面を表示部250に表示させる。
続いて、図15及び図16を参照して、本開示の実施形態に係る通信制御処理の例を説明する。
図15は、本開示の実施形態に係る通信制御処理全体の概略的な流れの一例を示すシーケンス図である。
図16は、本開示の実施形態に係る基地局側の通信制御処理の概略的な流れの一例を示すフローチャートである。当該通信制御処理は、リファレンス信号の送信に係る処理である。
続いて、図17~図22を参照して、本開示の実施形態に係る第1~第4の変形例を説明する。
まず、図17を参照して、本開示の実施形態に係る第1の変形例を説明する。
上述した実施形態の例では、基地局100は、上記2つ以上のアンテナグループの各々によりリファレンス信号を送信する。そして、基地局100は、各アンテナグループについて、端末装置200により通知される重み係数の推奨セットを、端末装置200へのビームを形成するための重み係数の上記セットとして取得する。即ち、上述した実施形態の例は、コードブックに基づくプリコーディングを使用する方式を採用する。
-アンテナグループごとのリファレンス信号の送信
第1の変形例では、送信制御部151は、上記2つ以上のアンテナグループの各々によるリファレンス信号の送信を制御しなくてもよく、又は当該送信を制御しなくてもよい。即ち、基地局100は、上記2つ以上のアンテナグループの各々によりリファレンス信号を送信してもよく、又は当該リファレンス信号を送信しなくてもよい。
-重み係数の推奨セットの取得
とりわけ第1の変形例では、情報取得部153は、端末装置200により送信されるリファレンス信号の受信に応じて算出される重み係数のセットを、端末装置200へのビームを形成するための重み係数のセットとして取得する。
第1の変形例でも、推定重み決定部261は、上記2つ以上のアンテナグループの各々について、端末装置200へのビームを形成するための重み係数の推奨セットを決定してもよく、通知部263は、当該推奨セットを通知してもよい。あるいは、第1の変形例では、推定重み決定部261は、上記2つ以上のアンテナグループの各々について、端末装置200へのビームを形成するための重み係数の推奨セットを決定しなくてもよく、通知部263は、当該推奨セットを通知しなくてもよい。
図17は、第1の変形例に係る通信制御処理全体の概略的な流れの一例を示すシーケンス図である。
次に、図18を参照して、本開示の実施形態に係る第2の変形例を説明する。
上述した実施形態の例では、基地局100が、上記2つ以上のアンテナグループについての上記重み係数の上記セットに基づいて、端末装置200への3次元ビームを形成するための、上記複数のアンテナ素子についての重み係数のセットを決定する。
推定重み決定部261は、重み係数のセットを決定する。例えば、推定重み決定部261は、重み係数の推奨セットを決定する。
とりわけ第2の変形例では、通知部263は、端末装置200への3次元ビームを形成するための、上記複数のアンテナ素子についての重み係数の推奨セットを通知する。例えば、通知部263は、上記推奨セットを示すインデックス(コードブックインデックス)の通知により、上記複数のアンテナ素子についての上記重み係数の上記セットを通知する。
とりわけ第2の変形例では、情報取得部153は、端末装置200への3次元ビームを形成するための、上記複数のアンテナ素子についての重み係数のセットを取得する。
重み決定部155は、端末装置200への3次元ビームを形成するための、上記複数のアンテナ素子についての重み係数のセットを最終的に決定する。
図18は、第2の変形例に係る通信制御処理全体の概略的な流れの一例を示すシーケンス図である。
次に、図19及び図20を参照して、本開示の実施形態に係る第3の変形例を説明する。
第3の変形例によれば、端末装置200へのビームの放射方向と水平面とのなす角度に応じて、少なくとも1つのアンテナグループについて、端末装置200へのビームを形成するための重み係数のセットが変わる。
第3の変形例では、情報取得部153は、端末装置200へのビームの放射方向と水平面とのなす角度が所定の角度範囲外にある場合には、当該角度が当該角度範囲内にある場合よりも、少なくとも1つのアンテナグループについて、重み係数の上記セットとして、より弱い指向性を有するビームを形成するための重み係数のセットを取得する。
例えば、端末装置200へのビームの放射方向と水平面とのなす上記角度が上記所定の角度範囲内にある。第3の変形例では、この場合に、重み決定部155は、端末装置200への3次元ビームを形成するための、上記複数のアンテナ素子についての重み係数のセットを決定する。即ち、上記角度が上記所定の角度範囲内にある場合には、3次元ビームを形成するための重み係数のセットが決定される。
例えば、第3の変形例では、推定重み決定部261は、端末装置200へのビームの放射方向と水平面とのなす角度が所定の角度範囲外にある場合には、当該角度が当該角度範囲内にある場合よりも、少なくとも1つのアンテナグループについて、重み係数の推奨セットとして、より弱い指向性を有するビームを形成するための重み係数のセットを決定する。
図20は、第3の変形例に係る通信制御処理全体の概略的な流れの一例を示すシーケンス図である。
次に、図21及び図22を参照して、本開示の実施形態に係る第4の変形例を説明する。
第4の変形例では、情報取得部153は、端末装置200へのビームの放射方向と水平面とのなす角度が所定の角度範囲内にある場合に、上記2つ以上のアンテナグループの各々について、端末装置200へのビームを形成するための重み係数のセットを取得する。
例えば、端末装置200へのビームの放射方向と水平面とのなす上記角度が上記所定の角度範囲内にある。第4の変形例では、この場合に、重み決定部155は、上記2つ以上のアンテナグループについての上記重み係数の上記セットに基づいて、上記複数のアンテナ素子についての重み係数のセットを決定する。
例えば、端末装置200へのビームの放射方向と水平面とのなす角度が所定の角度範囲内にある。第4の変形例では、この場合に、推定重み決定部261は、上記2つ以上のアンテナグループの各々について、端末装置200へのビームを形成するための重み係数の推奨セットを決定する。
-角度が角度範囲内にあるケース
図21は、第4の変形例に係る通信制御処理全体の概略的な流れの第1の例を示すシーケンス図である。当該第1の例は、端末装置200へのビームの放射方向と水平面とのなす角度が所定の角度範囲内にある場合の例である。
図22は、第4の変形例に係る通信制御処理全体の概略的な流れの第2の例を示すシーケンス図である。当該第2の例は、端末装置200へのビームの放射方向と水平面とのなす角度が所定の角度範囲外にある場合の例である。
本開示に係る技術は、様々な製品へ応用可能である。例えば、基地局100は、マクロeNB、ピコeNB、又はホームeNBなどのいずれかの種類のeNB(evolved Node B)として実現されてもよい。その代わりに、基地局100は、NodeB又はBTS(Base Transceiver Station)などの他の種類の基地局として実現されてもよい。基地局100は、無線通信を制御する本体(基地局装置ともいう)と、本体とは別の場所に配置される1つ以上のRRH(Remote Radio Head)とを含んでもよい。
(第1の応用例)
図23は、本開示に係る技術が適用され得るeNBの概略的な構成の第1の例を示すブロック図である。eNB800は、1つ以上のアンテナ810、及び基地局装置820を有する。各アンテナ810及び基地局装置820は、RFケーブルを介して互いに接続され得る。
図24は、本開示に係る技術が適用され得るeNBの概略的な構成の第2の例を示すブロック図である。eNB830は、1つ以上のアンテナ840、基地局装置850、及びRRH860を有する。各アンテナ840及びRRH860は、RFケーブルを介して互いに接続され得る。また、基地局装置850及びRRH860は、光ファイバケーブルなどの高速回線で互いに接続され得る。
(第1の応用例)
図25は、本開示に係る技術が適用され得るスマートフォン900の概略的な構成の一例を示すブロック図である。スマートフォン900は、プロセッサ901、メモリ902、ストレージ903、外部接続インタフェース904、カメラ906、センサ907、マイクロフォン908、入力デバイス909、表示デバイス910、スピーカ911、無線通信インタフェース912、1つ以上のアンテナスイッチ915、1つ以上のアンテナ916、バス917、バッテリー918及び補助コントローラ919を備える。
図26は、本開示に係る技術が適用され得るカーナビゲーション装置920の概略的な構成の一例を示すブロック図である。カーナビゲーション装置920は、プロセッサ921、メモリ922、GPS(Global Positioning System)モジュール924、センサ925、データインタフェース926、コンテンツプレーヤ927、記憶媒体インタフェース928、入力デバイス929、表示デバイス930、スピーカ931、無線通信インタフェース933、1つ以上のアンテナスイッチ936、1つ以上のアンテナ937及びバッテリー938を備える。
ここまで、図6~図26を参照して、本開示の実施形態に係る各装置及び各処理を説明した。本開示に係る実施形態によれば、情報取得部153は、3次元ビームを形成可能な指向性アンテナ101に含まれる複数のアンテナ素子の一部をそれぞれ含む2つ以上のアンテナグループの各々について、端末装置200へのビームを形成するための重み係数のセットを取得する。そして、重み決定部155は、上記2つ以上のアンテナグループについての上記重み係数の上記セットに基づいて、端末装置200への3次元ビームを形成するための、上記複数のアンテナ素子についての重み係数のセットを決定する。
さらに例えば、送信制御部151は、上記2つ以上のアンテナグループの各々によるリファレンス信号の送信を制御する。
例えば、情報取得部153は、端末装置200により通知される重み係数の推奨セットを、上記重み係数の上記セットとして取得する。
第1の変形例では、情報取得部153は、端末装置200により送信されるリファレンス信号の受信に応じて算出される重み係数のセットを、端末装置200へのビームを形成するための重み係数のセットとして取得する。
第3の変形例では、情報取得部153は、端末装置200へのビームの放射方向と水平面とのなす角度が所定の角度範囲外にある場合には、当該角度が当該角度範囲内にある場合よりも、少なくとも1つのアンテナグループについて、重み係数の上記セットとして、より弱い指向性を有するビームを形成するための重み係数のセットを取得する。例えば、端末装置200へのビームの放射方向と水平面とのなす上記角度が上記所定の角度範囲内にある。この場合に、重み決定部155は、端末装置200への3次元ビームを形成するための、上記複数のアンテナ素子についての重み係数のセットを決定する。一方、例えば、端末装置200へのビームの放射方向と水平面とのなす上記角度が上記所定の角度範囲外にある。この場合に、重み決定部155は、端末装置200へのビームを形成するための、上記複数のアンテナ素子についての重み係数のセットを決定する。
(1)
3次元ビームを形成可能な指向性アンテナに含まれる複数のアンテナ素子の一部をそれぞれ含む2つ以上のアンテナグループの各々について、端末装置へのビームを形成するための重み係数のセットを取得する取得部と、
前記2つ以上のアンテナグループについての前記重み係数の前記セットに基づいて、前記端末装置への3次元ビームを形成するための、前記複数のアンテナ素子についての重み係数のセットを決定する決定部と、
を備える通信制御装置。
(2)
前記2つ以上のアンテナグループは、第1の方向に並ぶ少なくとも2つのアンテナ素子を含む第1のアンテナグループと、前記第1の方向とは異なる第2の方向に並ぶ少なくとも2つのアンテナ素子を含む第2のアンテナグループとを含む、前記(1)に記載の通信制御装置。
(3)
前記複数のアンテナ素子は、前記第1の方向及び前記第2の方向に平行な平面に沿って配置されたアンテナ素子である、前記(2)に記載の通信制御装置。
(4)
前記第1の方向及び前記第2の方向は、互いに直交する、前記(2)又は(3)に記載の通信制御装置。
(5)
前記第2の方向は、水平面と平行な方向である、前記(4)に記載の通信制御装置。
(6)
前記決定部は、前記第1のアンテナグループについての重み係数のセットを示す行列と、前記第2のアンテナグループについての重み係数のセットを示す行列との乗算を通じて、前記複数のアンテナ素子についての前記重み係数の前記セットを決定する、前記(4)又は(5)に記載の通信制御装置。
(7)
前記2つ以上のアンテナグループの各々によるリファレンス信号の送信を制御する送信制御部をさらに備える、前記(1)~(6)のいずれか1項に記載の通信制御装置。
(8)
前記取得部は、前記端末装置により通知される重み係数の推奨セットを、前記重み係数の前記セットとして取得する、前記(7)に記載の通信制御装置。
(9)
前記推奨セットの通知は、重み係数の複数の推奨セット候補のうちの1つを示すインデックスの通知である、前記(8)に記載の通信制御装置。
(10)
前記複数の推奨セット候補は、コードブックに含まれる重み係数のセットであり、
前記インデックスは、前記コードブックのコードブックインデックスである、
前記(9)に記載の通信制御装置。
(11)
前記送信制御部は、前記2つ以上のアンテナグループが、異なるリソースブロックでリファレンス信号を送信するように、前記2つ以上のアンテナグループの各々によるリファレンス信号の送信を制御する、前記(7)~(10)のいずれか1項に記載の通信制御装置。
(12)
前記送信制御部は、前記2つ以上のアンテナグループが、少なくともいずれかの帯域幅の周波数帯域内で、異なる時間のリソースブロックでリファレンス信号を送信するように、前記2つ以上のアンテナグループの各々によるリファレンス信号の送信を制御する、前記(11)に記載の通信制御装置。
(13)
前記送信制御部は、前記2つ以上のアンテナグループが、少なくともいずれかの時間内で、異なる周波数帯域のリソースブロックでリファレンス信号を送信するように、前記2つ以上のアンテナグループの各々によるリファレンス信号の送信を制御する、前記(11)又は(12)に記載の通信制御。
(14)
前記取得部は、前記端末装置により送信されるリファレンス信号の受信に応じて算出される重み係数のセットを、前記重み係数の前記セットとして取得する、前記(1)~(6)のいずれか1項に記載の通信制御装置。
(15)
前記取得部は、前記端末装置へのビームの放射方向と水平面とのなす角度が所定の角度範囲外にある場合には、当該角度が当該角度範囲内にある場合よりも、前記2つ以上のアンテナグループのうちの少なくとも1つのアンテナグループについて、前記重み係数の前記セットとして、より弱い指向性を有するビームを形成するための重み係数のセットを取得し、
前記決定部は、前記角度が前記所定の角度範囲内にある場合には、前記端末装置への3次元ビームを形成するための、前記複数のアンテナ素子についての重み係数のセットを決定し、前記角度が前記所定の角度範囲外にある場合には、前記端末装置へのビームを形成するための、前記複数のアンテナ素子についての重み係数のセットを決定する、
前記(1)~(14)のいずれか1項に記載の通信制御装置。
(16)
前記取得部は、前記端末装置へのビームの放射方向と水平面とのなす角度が所定の角度範囲内にある場合に、前記2つ以上のアンテナグループの各々について、前記重み係数の前記セットを取得し、
前記決定部は、前記角度が前記所定の角度範囲内にある場合に、前記2つ以上のアンテナグループについての前記重み係数の前記セットに基づいて、前記複数のアンテナ素子についての前記重み係数のセットを決定する、
前記(1)~(14)のいずれか1項に記載の通信制御装置。
(17)
前記決定部は、前記角度が前記所定の角度範囲外にある場合に、前記端末装置へのビームを形成するための、前記複数のアンテナ素子よりも少ないアンテナ素子についての重み係数のセットを決定する、前記(16)に記載の通信制御装置。
(18)
前記複数のアンテナ素子よりも少ないアンテナ素子は、前記2つ以上のアンテナグループのうちの一部のアンテナグループに含まれるアンテナ素子である、前記(17)に記載の通信制御装置。
(19)
3次元ビームを形成可能な指向性アンテナに含まれる複数のアンテナ素子の一部をそれぞれ含む2つ以上のアンテナグループの各々について、端末装置へのビームを形成するための重み係数のセットを取得することと、
前記2つ以上のアンテナグループについての前記重み係数の前記セットに基づいて、前記端末装置への3次元ビームを形成するための、前記複数のアンテナ素子についての重み係数のセットを決定することと、
を含む通信制御方法。
(20)
端末装置であって、
3次元ビームを形成可能な指向性アンテナに含まれる複数のアンテナ素子の一部をそれぞれ含む2つ以上のアンテナグループの各々により送信されるリファレンス信号の受信に応じて、当該2つ以上のアンテナグループの各々について、前記端末装置へのビームを形成するための重み係数の推奨セットを決定する決定部と、
前記2つ以上のアンテナグループの各々についての前記推奨セットを通知する通知部と、
を備え、
前記2つ以上のアンテナグループについての前記推奨セットは、前記端末装置への3次元ビームを形成するための前記複数のアンテナ素子についての重み係数のセットを決定するのに使用される情報である、
端末装置。
10 セル
20 3次元ビーム
30 通信領域
100 基地局
151 送信制御部
153 情報取得部
153 重み決定部
200 端末装置
261 推奨重み決定部
263 通知部
Claims (20)
- 3次元ビームを形成可能な指向性アンテナに含まれる複数のアンテナ素子の一部をそれぞれ含む2つ以上のアンテナグループの各々について、端末装置へのビームを形成するための重み係数のセットを取得する取得部と、
前記2つ以上のアンテナグループについての前記重み係数の前記セットに基づいて、前記端末装置への3次元ビームを形成するための、前記複数のアンテナ素子についての重み係数のセットを決定する決定部と、
を備える通信制御装置。 - 前記2つ以上のアンテナグループは、第1の方向に並ぶ少なくとも2つのアンテナ素子を含む第1のアンテナグループと、前記第1の方向とは異なる第2の方向に並ぶ少なくとも2つのアンテナ素子を含む第2のアンテナグループとを含む、請求項1に記載の通信制御装置。
- 前記複数のアンテナ素子は、前記第1の方向及び前記第2の方向に平行な平面に沿って配置されたアンテナ素子である、請求項2に記載の通信制御装置。
- 前記第1の方向及び前記第2の方向は、互いに直交する、請求項2に記載の通信制御装置。
- 前記第2の方向は、水平面と平行な方向である、請求項4に記載の通信制御装置。
- 前記決定部は、前記第1のアンテナグループについての重み係数のセットを示す行列と、前記第2のアンテナグループについての重み係数のセットを示す行列との乗算を通じて、前記複数のアンテナ素子についての前記重み係数の前記セットを決定する、請求項4に記載の通信制御装置。
- 前記2つ以上のアンテナグループの各々によるリファレンス信号の送信を制御する送信制御部をさらに備える、請求項1に記載の通信制御装置。
- 前記取得部は、前記端末装置により通知される重み係数の推奨セットを、前記重み係数の前記セットとして取得する、請求項7に記載の通信制御装置。
- 前記推奨セットの通知は、重み係数の複数の推奨セット候補のうちの1つを示すインデックスの通知である、請求項8に記載の通信制御装置。
- 前記複数の推奨セット候補は、コードブックに含まれる重み係数のセットであり、
前記インデックスは、前記コードブックのコードブックインデックスである、
請求項9に記載の通信制御装置。 - 前記送信制御部は、前記2つ以上のアンテナグループが、異なるリソースブロックでリファレンス信号を送信するように、前記2つ以上のアンテナグループの各々によるリファレンス信号の送信を制御する、請求項7に記載の通信制御装置。
- 前記送信制御部は、前記2つ以上のアンテナグループが、少なくともいずれかの帯域幅の周波数帯域内で、異なる時間のリソースブロックでリファレンス信号を送信するように、前記2つ以上のアンテナグループの各々によるリファレンス信号の送信を制御する、請求項11に記載の通信制御装置。
- 前記送信制御部は、前記2つ以上のアンテナグループが、少なくともいずれかの時間内で、異なる周波数帯域のリソースブロックでリファレンス信号を送信するように、前記2つ以上のアンテナグループの各々によるリファレンス信号の送信を制御する、請求項11に記載の通信制御。
- 前記取得部は、前記端末装置により送信されるリファレンス信号の受信に応じて算出される重み係数のセットを、前記重み係数の前記セットとして取得する、請求項1に記載の通信制御装置。
- 前記取得部は、前記端末装置へのビームの放射方向と水平面とのなす角度が所定の角度範囲外にある場合には、当該角度が当該角度範囲内にある場合よりも、前記2つ以上のアンテナグループのうちの少なくとも1つのアンテナグループについて、前記重み係数の前記セットとして、より弱い指向性を有するビームを形成するための重み係数のセットを取得し、
前記決定部は、前記角度が前記所定の角度範囲内にある場合には、前記端末装置への3次元ビームを形成するための、前記複数のアンテナ素子についての重み係数のセットを決定し、前記角度が前記所定の角度範囲外にある場合には、前記端末装置へのビームを形成するための、前記複数のアンテナ素子についての重み係数のセットを決定する、
請求項1に記載の通信制御装置。 - 前記取得部は、前記端末装置へのビームの放射方向と水平面とのなす角度が所定の角度範囲内にある場合に、前記2つ以上のアンテナグループの各々について、前記重み係数の前記セットを取得し、
前記決定部は、前記角度が前記所定の角度範囲内にある場合に、前記2つ以上のアンテナグループについての前記重み係数の前記セットに基づいて、前記複数のアンテナ素子についての前記重み係数のセットを決定する、
請求項1に記載の通信制御装置。 - 前記決定部は、前記角度が前記所定の角度範囲外にある場合に、前記端末装置へのビームを形成するための、前記複数のアンテナ素子よりも少ないアンテナ素子についての重み係数のセットを決定する、請求項16に記載の通信制御装置。
- 前記複数のアンテナ素子よりも少ないアンテナ素子は、前記2つ以上のアンテナグループのうちの一部のアンテナグループに含まれるアンテナ素子である、請求項17に記載の通信制御装置。
- 3次元ビームを形成可能な指向性アンテナに含まれる複数のアンテナ素子の一部をそれぞれ含む2つ以上のアンテナグループの各々について、端末装置へのビームを形成するための重み係数のセットを取得することと、
前記2つ以上のアンテナグループについての前記重み係数の前記セットに基づいて、前記端末装置への3次元ビームを形成するための、前記複数のアンテナ素子についての重み係数のセットを決定することと、
を含む通信制御方法。 - 端末装置であって、
3次元ビームを形成可能な指向性アンテナに含まれる複数のアンテナ素子の一部をそれぞれ含む2つ以上のアンテナグループの各々により送信されるリファレンス信号の受信に応じて、当該2つ以上のアンテナグループの各々について、前記端末装置へのビームを形成するための重み係数の推奨セットを決定する決定部と、
前記2つ以上のアンテナグループの各々についての前記推奨セットを通知する通知部と、
を備え、
前記2つ以上のアンテナグループについての前記推奨セットは、前記端末装置への3次元ビームを形成するための前記複数のアンテナ素子についての重み係数のセットを決定するのに使用される情報である、
端末装置。
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US20160173176A1 (en) | 2016-06-16 |
EP3043489A1 (en) | 2016-07-13 |
EP3043489B1 (en) | 2022-03-02 |
TW201513597A (zh) | 2015-04-01 |
US10063293B2 (en) | 2018-08-28 |
EP3043489A4 (en) | 2017-04-05 |
TWI650968B (zh) | 2019-02-11 |
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