WO2014119276A1 - 通信システムにおける端末装置、基地局装置およびコードブック共有方法 - Google Patents
通信システムにおける端末装置、基地局装置およびコードブック共有方法 Download PDFInfo
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- WO2014119276A1 WO2014119276A1 PCT/JP2014/000397 JP2014000397W WO2014119276A1 WO 2014119276 A1 WO2014119276 A1 WO 2014119276A1 JP 2014000397 W JP2014000397 W JP 2014000397W WO 2014119276 A1 WO2014119276 A1 WO 2014119276A1
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- codebook
- code book
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- precoding matrix
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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
- H04B7/0617—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the transmitting station using simultaneous transmission of weighted versions of same signal for beam forming
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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
- H04B7/04—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas
- H04B7/08—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the receiving station
- H04B7/0837—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the receiving station using pre-detection combining
- H04B7/0842—Weighted combining
- H04B7/086—Weighted combining using weights depending on external parameters, e.g. direction of arrival [DOA], predetermined weights or beamforming
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04W—WIRELESS COMMUNICATION NETWORKS
- H04W88/00—Devices specially adapted for wireless communication networks, e.g. terminals, base stations or access point devices
- H04W88/02—Terminal devices
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04W—WIRELESS COMMUNICATION NETWORKS
- H04W88/00—Devices specially adapted for wireless communication networks, e.g. terminals, base stations or access point devices
- H04W88/08—Access point devices
Definitions
- the present invention relates to a communication system using precoding, and more particularly to a terminal apparatus, a base station apparatus, and a codebook sharing method in the communication system.
- a base station performs beamforming based on channel information fed back from a terminal to improve communication quality and system capacity.
- FDD Frequency Division Duplexing
- a feedback method using a code book is adopted to reduce the amount of feedback information.
- a precoding matrix table (codebook) is shared in advance between the terminal and the base station, and the terminal uses the index of the precoding matrix having the highest correlation based on the channel response estimated in the downlink.
- the index in this codebook is called Precoding Matrix Indicator (PMI).
- PMI Precoding Matrix Indicator
- Non-Patent Document 1 With respect to horizontal beamforming, for example, by using a precoding matrix described in Non-Patent Document 1, it is possible to perform codebook-based beamforming for the entire cell coverage.
- the vertical beam angle is defined as an angle at which the main beam direction of a beam realized by a certain precoding matrix is looked down from the base station.
- 3GPP TS 36.211 V9.1.0 (2010-03): “3rd Generation Partnership Project; Technical Technical Specification Group Radio Access Network; Evolved Universal Universal Terrestrial Radio Access (E-UTRA); Physical Channels and Modulation (pages 50-51) "Throughput improvement in mobile communications from cells with large, medium and small cells mixed -Base station antenna vertical directivity control using precoding and adjacent base station coordinated transmission-" IEICE Tech. RCS2012-16 , Pp91-96, 2012 (pages 92-93)
- Non-Patent Document 2 the cell environment such as the height of the base station, the cell radius, the obstacles around the base station and the distribution of the surrounding cells greatly affects the communication quality and system capacity. .
- a codebook common to cells as described in Non-Patent Document 1 is simply expanded and used as a codebook for beamforming in the vertical direction, improvement in system capacity by beamforming is limited.
- the codebook is determined by the beam angle interval (hereinafter referred to as the beam angle interval) and the range (hereinafter referred to as the beam angle range) realized by the precoding matrix. Problems caused by the setting of the angular interval will be described.
- the beam angle range in horizontal plane beamforming, the horizontal plane angle of cell coverage as seen from the base phase is constant regardless of the base station height, but in vertical plane beamforming, the vertical plane angle of coverage seen from the base station is the same as the base station height. It changes depending on. For this reason, if a beam is prepared with a fixed vertical plane angle without considering the base station height and cell radius, for example, a base station installed on a higher floor has a part of the beam pointing out of the cell coverage, so Base stations installed on the floor irradiate only a part of the area within the beam coverage. It is clear that the beam pointing out of the cell coverage does not contribute to the improvement of the system capacity in a limited amount of feedback information, and may increase inter-cell interference.
- the vertical plane angle should be increased to irradiate only the necessary area within the beam coverage. Is desirable.
- the distance between the main beam irradiation position on the ground plane of each beam and the distance between the base stations is the same, so the path loss condition is also the same for each beam. Therefore, arranging the beams at equal intervals between the horizontal plane irradiation positions of the beams is an optimal beam arrangement for reducing the drop in the received signal strength characteristic realized by a plurality of beams (Non-patent Document 1). .
- the received intensity characteristics realized by each beam are different, it is not necessarily the optimum beam arrangement to prepare beams at equidistant intervals.
- the distance between the position of the ground plane irradiated by the main beam and the base station differs from beam to beam even if the beam ground plane irradiation positions L1-L3 are equally spaced. Therefore, the influence of path loss also varies from beam to beam.
- the received signal intensity characteristic becomes slower than in the case of horizontal plane beam forming, and the difference in intensity for each beam is reduced.
- FIG. 1C even when the same beam angle is prepared, the interval between the beam irradiation positions varies depending on the position in the cell irradiated with the beam, that is, the distance from the base station.
- the interval between the beam irradiation positions varies even for beams having the same beam angle. That is, the beam irradiation position interval L4-L5 by the high base station shown in FIG. 2A is wider than the beam irradiation position interval L6-L7 by the low base station shown in FIG.
- a beam is realized in a part of the area by uniformly applying the codebook common to the cells to the vertical beamforming without considering the difference in the cell environment.
- the codebook common to the cells is uniformly applied to vertical beamforming, the distance between the main beam irradiation positions increases as the distance from the base station is irradiated (the beam angle in the vertical direction decreases). A region where a sufficient gain cannot be obtained occurs, and inter-cell interference also increases. For this reason, a terminal far from any beam irradiation position cannot obtain the gain of beam forming, and the improvement of the system capacity is limited.
- an object of the present invention is to provide a communication system, a terminal device, a base station device, and a codebook sharing method that can improve system capacity using precoding according to a cell environment.
- a communication system is a communication system that performs beam directivity control by precoding using a codebook common to a base station and a terminal, and the base station determines a codebook including cell environment information of the base station. And the base station and the terminal generate a common code book based on the code book determination information.
- a terminal apparatus is a terminal apparatus in a communication system that performs beam directivity control by precoding using a codebook, and receives codebook determination information including cell environment information of the base station from a base station. It has a communication means and a code book generating means for generating a code book common to the base station based on the code book determination information.
- a base station apparatus is a base station apparatus in a communication system that performs beam directivity control by precoding using a code book, and transmits code book determination information including cell environment information of the base station apparatus to the terminal. It has a communication means to transmit, and a code book generating means for generating a code book common to the terminal based on the code book determination information.
- a codebook sharing method is a codebook sharing method in a communication system for performing beam directivity control by precoding using a codebook common to a base station and a terminal, wherein the base station is a cell of the base station. Code terminal determination information including environmental information is notified to the terminal, and the base station and the terminal generate a common code book based on the code book determination information.
- a codebook sharing method is a codebook sharing method in a communication system in which beam directivity control is performed by precoding using a codebook, for determining a codebook including cell environment information of the base station from a base station. Information is received, and a code book common to the base station is generated based on the code book determination information.
- a codebook sharing method is a codebook sharing method in a communication system that performs beam directivity control by precoding using a codebook, and the codebook determination information including cell environment information of the base station is transmitted to a terminal. And generating a code book common to the terminal based on the code book determination information.
- the codebook determination information including the cell environment information is notified from the base station side to the terminal side, and the base station and the terminal can share a common codebook based on the codebook determination information.
- the base station and the terminal can share a common codebook based on the codebook determination information.
- FIG. 1A is a schematic diagram showing a case where the beam irradiation positions in the vertical plane beam forming are equally spaced
- FIG. 1B is a graph showing a reception intensity characteristic realized by each beam in FIG. 1 (C) is a schematic diagram showing a case where the beam angle intervals in vertical plane beam forming are equal
- FIG. 2A is a schematic diagram showing the interval between the beam irradiation positions when the height of the base station is high
- FIG. 2B is a schematic diagram showing the interval between the beam irradiation positions when the height of the base station is low.
- FIG. 3A is a schematic diagram of a base station and its cell in a wireless communication system according to one embodiment of the present invention
- FIG. 3A is a schematic diagram of a base station and its cell in a wireless communication system according to one embodiment of the present invention
- FIG. 3B is a diagram showing an example of a code book in this embodiment.
- FIG. 4 is a block diagram showing configurations of a base station and a terminal in the wireless communication system according to the first embodiment of the present invention.
- FIG. 5 is a schematic flowchart for explaining the system operation of the first embodiment shown in FIG.
- FIG. 6 is a block diagram showing configurations of a base station and a terminal in a wireless communication system according to the second embodiment of the present invention.
- FIG. 7 is a schematic flowchart for explaining the system operation of the second embodiment shown in FIG.
- FIG. 8 is a block diagram showing configurations of a base station and a terminal in a wireless communication system according to the third embodiment of the present invention.
- FIG. 9 is a schematic flowchart for explaining the system operation of the third embodiment shown in FIG.
- FIG. 10 is a block diagram showing configurations of a base station and a terminal in a wireless communication system according to the fourth embodiment of the present invention.
- FIG. 11 is a schematic flowchart for explaining the system operation of the fourth embodiment shown in FIG.
- FIG. 12 is a block diagram showing configurations of a base station and a terminal in a wireless communication system according to the fifth embodiment of the present invention.
- FIG. 13 is a diagram showing an example of a superset table in the fifth embodiment.
- FIG. 14 is a schematic flowchart for explaining the system operation of the fifth embodiment shown in FIG. FIG.
- FIG. 15 is a block diagram showing configurations of a base station and a terminal in a wireless communication system according to the sixth embodiment of the present invention.
- FIG. 16 is a schematic flowchart for explaining the system operation of the sixth embodiment shown in FIG.
- FIG. 17 is a block diagram showing configurations of a base station and a terminal in a wireless communication system according to the seventh embodiment of the present invention.
- FIG. 18 is a schematic flowchart for explaining the system operation of the seventh embodiment shown in FIG.
- FIG. 19 is a block diagram showing configurations of a base station and a terminal in a wireless communication system according to the eighth embodiment of the present invention.
- FIG. 20 is a schematic flowchart for explaining the system operation of the eighth embodiment shown in FIG. FIG.
- FIG. 21 is a block diagram showing configurations of a base station and a terminal in a wireless communication system according to the ninth embodiment of the present invention.
- FIG. 22 is a block diagram showing a functional configuration of the index selection unit of the base station and terminal in FIG.
- FIG. 23 is a flowchart showing the operation of the index selection unit shown in FIG.
- FIG. 24 is a diagram showing the relationship between the beam pattern and the beam coverage area in the ninth embodiment.
- FIG. 25 is a diagram showing the relationship between the beam coverage area boundary angle and the beam coverage area in the ninth embodiment.
- FIG. 26 is a diagram showing the relationship between the beam coverage area and the metric in the ninth embodiment.
- FIG. 27 is a schematic flowchart for explaining the system operation of the ninth embodiment shown in FIG. FIG.
- FIG. 28 is a block diagram showing configurations of a base station and a terminal in the wireless communication system according to the tenth embodiment of the present invention.
- FIG. 29 is a schematic flowchart for explaining the system operation of the tenth embodiment shown in FIG.
- FIG. 30 is a block diagram showing configurations of a base station and a terminal in the wireless communication system according to the eleventh embodiment of the present invention.
- FIG. 31 is a schematic flow chart for explaining the system operation of the eleventh embodiment shown in FIG.
- the height of the transmitting antenna of the base station 10 from the ground (cell surface) is h, and the distance on the cell surface from the base station 10 to the end of the cell 11 (hereinafter, for convenience).
- Cell radius is defined as dc .
- the terminal 20 communicating with the base station 10 receives the codebook determination information including the cell environment information from the base station 10, the terminal 20 generates a cell-specific precoding matrix based on the codebook determination information.
- the code book illustrated in FIG. 3B is determined.
- the code book in this embodiment is not a single fixed code book but a code book reflecting the environment for each cell.
- the terminal 20 feeds back a codebook index (PMI) as channel information to the base station 10 using such a cell-specific codebook.
- the feedback size is Nfb.
- the base station when a codebook reflecting a cell environment is shared between a base station and a terminal, the base station notifies the terminal of cell-specific parameters as codebook determination information, and the terminal A codebook composed of precoding matrices calculated based on cell-specific parameters is determined. As a result, it is possible to share a codebook without a useless precoding matrix, and it is possible to improve the system capacity.
- the cell-specific parameter may be any information that reflects the cell environment, as will be described later, the height h and the cell radius d c such cell environment information of the base station 10, the beam angle is dependent on these cells environment and For example, beam angle information related to the beam angle interval can be used.
- the cell environment information of the height h and the cell radius d c of the base station 10, a at a predetermined value depending on the cell environment such as the distribution of electromagnetic interference, neighbor in the neighborhood of the base station 10 May be.
- the beam angle information of the cell of the limited or the like of the beam irradiation region to avoid the distribution or inter-cell interference electromagnetic interference, neighbor of neighboring base stations as well as base stations high h and cell radius d c It may depend on the specific environment.
- embodiments of the present invention will be described in detail with reference to the drawings.
- the base station 10_1 includes a communication unit 101 for communicating with the terminal 20_1, a database 102, a beam angle range calculation unit 103, a beam angle interval calculation unit 104, a precoding matrix calculation unit 105, an index allocation unit 106, and a codebook storage unit 107. And a control unit 108.
- the beam angle range calculation unit 103 and the beam angle interval calculation unit 104 generate beam angle information
- the precoding matrix calculation unit 105 and the index allocation unit 106 generate a codebook to be shared.
- the database 102 stores cell environment information including the cell radius d c , the base station height h, the PMI feedback size Nfb [bit], and, if necessary, the obstacles around the base station and the distribution of neighboring cells.
- Cell radius d c, the transmission power, propagation models or beam pattern to the received signal strength theoretical value calculated from the model may be defined as the radius of the region is equal to or greater than a predetermined value, the cell edge of the cell coverage that assumed at the time of cell design And the maximum value or average value of the distance between the base station position and the base station position.
- the base station height h and the PMI feedback size Nfb are set at the time of installation or at the time of system request.
- Beam angle range calculation unit 103 the beam angle range calculated by entering the cell radius d c and the base station height h from the database 102, the beam angle interval calculator 104 and the beam angle range ⁇ r from the beam angle range calculation unit 103
- the beam angle interval ⁇ is calculated using the PMI feedback size Nfb from the database 102. The calculation of the beam angle range ⁇ r and the beam angle interval ⁇ will be described later.
- the precoding matrix calculation unit 105 inputs the beam angle interval ⁇ from the beam angle interval calculation unit 104 and the beam angle range ⁇ r from the beam angle range calculation unit 103, and calculates the precoding matrix Vi.
- the index assigning unit 106 assigns a predetermined index to the codebook precoding matrix group input from the precoding matrix calculating unit 105.
- the control unit 108 stores the precoding matrix group and the assigned index in the codebook storage unit 107 as a codebook.
- the control unit 108 executes communication control according to the present embodiment and controls the above-described function units (101-107), and the beam angle range ⁇ r calculated by the beam angle range calculation unit 103 and the beam angle interval calculation unit 104. Is transmitted to the terminal 20_1 as the code book determination information.
- the terminal 20_1 includes a communication unit 201, a precoding matrix calculation unit 202, an index assignment unit 203, a codebook storage unit 204, and a control unit 205 for communicating with the base station 10_1. As will be described later, a codebook to be shared by the precoding matrix calculation unit 202 and the index allocation unit 203 is generated.
- the control unit 205 executes communication control according to this embodiment. That is, when cell specific parameters (beam angle information: beam angle range ⁇ r and beam angle interval ⁇ ) are received from the base station 10_1 through the broadcast channel or the dedicated channel, the precoding matrix calculation unit 105 performs the beam angle interval ⁇ and the beam angle range ⁇ r. The precoding matrix Vi is calculated from the above, and the index assigning unit 106 assigns a predetermined index to the calculated precoding matrix group for the codebook. Then, the control unit 205 stores the precoding matrix group and the index in the code book storage unit 204 as a code book.
- the precoding matrix calculation unit (105, 202), the index allocation unit (106, 203), and the codebook storage unit (107, 204) of the base station 10_1 and the terminal 20_1 basically perform the same processing.
- control unit 108 of the base station 10_1 When the base station is installed, the control unit 108 of the base station 10_1 generates a code book according to the procedure described below and stores it in the code book storage unit 107. Thereafter, regeneration may be performed at regular intervals or when the cell environment or system requirements are changed.
- the control unit 108 reads out the cell radius d c , the base station height h, and the PMI feedback size Nfb, which are cell environment information of the base station 10_1, from the database 102 (operation S110), the beam angle range calculation unit 103, and the beam angle
- the interval calculation unit 104 is controlled to calculate the beam angle range ⁇ r and the beam angle interval ⁇ (operation S111).
- the specific calculation procedure is as follows.
- Beam angle range calculation unit 103 calculates the beam angle range ⁇ r with a cell radius d c and the base station height h obtained from the database 102.
- ⁇ max is a fixed value ⁇ / 2
- ⁇ min is calculated by the following equation (1).
- the beam angle range ⁇ r is may be defined by a continuous value range between a lower limit value phi min and the upper limit value phi max, it is defined by discrete numerical ranges specify multiple beam angle Good.
- the beam angle interval calculation unit 104 divides the beam angle range ⁇ r by the PMI feedback size 2 Nfb ⁇ 1 to calculate a beam angle interval ⁇ for arranging the beams at equal intervals within the beam angle range.
- the beam angle interval ⁇ is calculated by the following equation (2).
- the precoding matrix calculation unit 105 performs a codebook precoding matrix group that realizes the beam angle range and the beam angle interval based on the beam angle range ⁇ r and the beam angle interval ⁇ by the following calculation procedure. ⁇ V ⁇ is calculated (operation S121).
- the main beam angle ⁇ i of each precoding matrix in the codebook is calculated using the beam angle range ⁇ r and the beam angle interval ⁇ .
- the i-th main beam angle ⁇ i is calculated by the following equation (3).
- a precoding matrix Vi corresponding to each ⁇ i is calculated.
- the beam vertical directivity g a ( ⁇ ) with respect to an arbitrary beam angle direction ⁇ is calculated by the following equation (4).
- N a is the number of antenna elements
- g e ( ⁇ ) is directional beams each antenna element forms
- [Delta] d is the interval of antennas disposed at equal intervals
- lambda is the wavelength.
- the vertical plane power directivity G p ( ⁇ , p) when precoding is applied can be calculated by the following equation (6).
- the number of bits when an index indicating an arbitrary precoding matrix in the codebook is expressed in a binary number becomes a specified PMI.
- the feedback size is Nfb or less.
- the control unit 108 notifies the code book determination information including the beam angle range ⁇ r and the beam angle interval ⁇ described above to the terminal 20_1 in the own cell through the communication unit 101 (operation S124).
- notification may be made using a broadcast channel (PBCH: Physical Broadcast CHannel) that notifies all terminals in the cell, or individually notified to a terminal that has made a connection request to the own cell. May be.
- PBCH Physical Broadcast CHannel
- the control unit 205 of the terminal 20_1 causes the precoding matrix calculation unit 202 and the index allocation unit 203 to be similar to the operations S121 to S123 on the base station 10_1 side. Control and generate codebook. That is, the precoding matrix calculation unit 202 uses the received beam angle range ⁇ r and the beam angle interval ⁇ , and for the codebook that realizes the beam angle range and the beam angle interval according to the above-described equations (3) to (7).
- the precoding matrix group ⁇ V ⁇ is calculated (operation S221).
- the control unit 205 stores the allocation result in the code book storage unit 204 (operation S223).
- the same cell-specific codebook stored in the codebook storage unit 107 of the base station 10_1 is stored in the codebook recording unit 204 of the terminal 20_1.
- the control unit 205 of the terminal 20_1 feeds back a code book index (PMI) as channel information to the base station 10_1.
- PMI code book index
- the cell-specific codebook is generated so as to satisfy the condition of the PMI feedback size Nfb.
- the base station 10_1 notifies the terminal 20_1 of the beam angle range ⁇ r and the beam angle interval ⁇ calculated according to the cell environment.
- a code book reflecting the cell environment can be shared between the base station and the terminal by the same processing. That is, a minimum necessary codebook suitable for a cell environment without useless precoding matrix and satisfying the PMI feedback condition can be shared between the base station and the terminal, and the system capacity can be improved.
- the beam angle interval ⁇ of the base station is previously stored in the database as a fixed value, so that the beam angle interval calculation unit can be omitted.
- the configuration and operation of the second embodiment will be described below.
- the configuration of the terminal 20_2 in the wireless communication system according to the second embodiment of the present invention is the same as that of the terminal 20_1 in the first embodiment.
- the base station 10_2 of the present embodiment is partially different from the base station 10_1 of the first embodiment, the same reference numerals are assigned to the same blocks, and descriptions thereof are omitted, and only different components are described. To do.
- the base station 10_2 In the database 102b of the base station 10_2, in addition to the cell radius d c , the base station height h, and the PMI feedback size Nfb [bit], a fixed beam angle interval ⁇ indicating the cell environment of the base station 10_2 is stored. . Therefore, the base station 10_2 does not need the beam angle interval calculation unit 104 in the first embodiment.
- the other configuration is basically the same as that of the base station 10_1 of the first embodiment shown in FIG. 4, but the operation of the precoding matrix calculation unit is partially different from that of the first embodiment.
- control unit 108 of the base station 10_2 When the base station is installed, the control unit 108 of the base station 10_2 generates a code book according to the procedure described below and stores it in the code book storage unit 107. Thereafter, regeneration may be performed at regular intervals or when the cell environment or system requirements are changed.
- the control unit 108 reads out the cell radius d c , the base station height h, the PMI feedback size Nfb, and the fixed beam angle interval ⁇ , which are cell environment information of the base station 10_2, from the database 102b (operation S110b).
- the angle range calculation unit 103 is controlled to calculate the beam angle range ⁇ r (operation S111b). The specific calculation procedure is as described in the first embodiment.
- the precoding matrix calculation unit 105b performs the calculation based on the calculated beam angle range ⁇ r and the fixed value beam angle interval ⁇ read from the database 102b according to the calculation procedure described in the first embodiment.
- a codebook precoding matrix group ⁇ V ⁇ that realizes a beam angle range and a beam angle interval is calculated (operation S121b).
- the precoding matrix calculation unit 105b executes control for limiting a part of the codebook so as to satisfy the condition of the PMI feedback size Nfb. Since this point is different from the first embodiment, the difference will be mainly described below, and the other operations are the same as those of the first embodiment, and the details are omitted.
- the precoding matrix calculation unit 105b When the number of precoding matrices in the calculated codebook precoding matrix group is equal to or larger than the PMI feedback size Nfb, the precoding matrix calculation unit 105b has the beam closest to the cell center, that is, the largest vertical beam angle. The beam is deleted from the codebook precoding matrix group. Then, the precoding matrix deletion operation is repeated until the number of precoding matrices in the codebook precoding matrix becomes equal to the PMI feedback size.
- the index assigning unit 106 sets i to the precoding matrix group V i obtained from the precoding matrix calculation unit 105 in the same manner as in the first embodiment. Allocation is performed as an index of the code book (operation S122), and the allocation result is stored in the code book storage unit 107 (operation S123).
- the control unit 108 notifies the terminal 20_2 in the own cell through the communication unit 101 of code book determination information including the calculated beam angle range ⁇ r and a fixed beam angle interval ⁇ (operation S124).
- notification may be made using a broadcast channel (PBCH: Physical Broadcast CHannel) that notifies all terminals in the cell, or individually notified to a terminal that has made a connection request to the own cell. May be.
- PBCH Physical Broadcast CHannel
- the control unit 205 of the terminal 20_2 like the operations S121b, S122, and S123 on the base station 10_2 side, the precoding matrix calculation unit 202 and the index allocation unit
- the code book is generated by controlling 203 and stored in the code book storage unit 204 (operations S221b, S222, and S223).
- the precoding matrix calculation unit 202 executes control for limiting a part of the codebook so as to satisfy the condition of the PMI feedback size Nfb, similarly to the operation S121b on the base station side.
- the same cell-specific codebook stored in the codebook storage unit 107 of the base station 10_2 is stored in the codebook recording unit 204 of the terminal 20_2.
- the control unit 205 of the terminal 20_2 feeds back a code book index (PMI) as channel information to the base station 10_2.
- PMI code book index
- the cell-specific codebook is generated so as to satisfy the condition of the PMI feedback size Nfb.
- the beam angle interval is changed, that is, in order from a narrow beam angle interval to a wide beam angle interval. If the PMI feedback size condition is not satisfied even after trial, the precoding matrix can be controlled to be deleted.
- the beam angle interval processing unit can be omitted by setting the beam angle interval ⁇ to a fixed value.
- the point of generating a codebook from a high h and the cell radius d c a base station by the terminal side is notified is different from the first embodiment.
- the configuration and operation of the third embodiment will be described below.
- the configuration of the base station 10_3 in the third embodiment of the present invention is the same as that of the base station 10_1 in the first embodiment.
- base station 10_3 is different in that notifies the code book determining information comprising a base station high h, cell radius d c and PMI feedback size Nfb to the terminal 20_3. Therefore, the beam angle range calculation unit 206 and the beam angle interval calculation unit 207 are added to the configuration of the terminal 20_1 of the first embodiment in the terminal 20_3 of the present embodiment. Since other configurations are the same as those of the first embodiment, the same reference numerals are assigned to the same blocks as those of the first embodiment, and operations different from those of the first embodiment will be mainly described.
- the control unit 205 of the terminal 20_3 When the terminal 20_3 receives the code book determining information comprising a base station high h, cell radius d c and PMI feedback size Nfb, the control unit 205 of the terminal 20_3, like the operation S111 of the base station 10_3 side, beam angle range The calculation unit 206 and the beam angle interval calculation unit 207 are controlled to calculate the beam angle range ⁇ r and the beam angle interval ⁇ (operation S211). Subsequently, the control unit 205 controls the precoding matrix calculation unit 202 and the index allocation unit 203 to generate a codebook, similarly to the operations S121 to S123 on the base station 10_3 side.
- the precoding matrix calculation unit 202 uses the calculated beam angle range ⁇ r and the beam angle interval ⁇ , and for the codebook that realizes the beam angle range and beam angle interval according to the above equations (3) to (7).
- the precoding matrix group ⁇ V ⁇ is calculated (operation S221).
- the control unit 205 stores the allocation result in the code book storage unit 204 (operation S223).
- the same cell-specific codebook stored in the codebook storage unit 107 of the base station 10_3 is stored in the codebook recording unit 204 of the terminal 20_3.
- the control unit 205 of the terminal 20_3 feeds back a code book index (PMI) as channel information to the base station 10_3.
- PMI code book index
- the cell-specific codebook is generated so as to satisfy the condition of the PMI feedback size Nfb.
- the beam angle interval ⁇ of the base station is stored in advance in the database as a fixed value. except a codebook from a radius d c and beam angle interval ⁇ is different from the second embodiment.
- the configuration and operation of the fourth embodiment will be described below. 4.1) System Configuration In FIG. 10, since the configuration of the base station 10_4 in the fourth embodiment of the present invention is the same as that of the base station 10_2 in the second embodiment, the same reference numerals are given and description thereof is omitted.
- the terminal 20_4 of this embodiment has a configuration in which a beam angle range calculation unit 206 is added to the base station 10_2 of the second embodiment, and the other configurations are the same as those of the second embodiment.
- the same reference numerals are assigned and the description is omitted, and only different components will be described.
- the control unit 108 of the base station 10_4 generates a code book through operations S110b, S111b, S121b, S122, and S123, and stores the codebook in the codebook storage unit 107, as in the second embodiment shown in FIG. Subsequently, the control unit 108 notifies the terminal 20_4 of the base station height h, the cell radius d c , the PMI feedback size Nfb, and the beam angle interval ⁇ read from the database 102 as codebook determination information (operation S124b).
- the control unit 205 of the terminal 20_3 calculates the beam angle range ⁇ r by controlling the beam angle range calculation unit 206, similarly to the operation S111b on the base station 10_3 side (operation S211d). Subsequently, the control unit 205 generates a code book by controlling the precoding matrix calculation unit 202 and the index allocation unit 203 in the same manner as the operations S121b, S122, and S123 on the base station 10_4 side, and stores them in the codebook recording unit 204. Store (operations S221b, S222, S223).
- the same cell-specific codebook stored in the codebook storage unit 107 of the base station 10_4 is stored in the codebook recording unit 204 of the terminal 20_4.
- the control unit 205 of the terminal 20_4 feeds back a code book index (PMI) as channel information to the base station 10_4.
- PMI code book index
- the cell-specific codebook is generated so as to satisfy the condition of the PMI feedback size Nfb.
- the beam angle interval is changed, that is, in order from a narrow beam angle interval to a wide beam angle interval. If the PMI feedback size condition is not satisfied even after trial, the precoding matrix can be controlled to be deleted.
- the base station height h indicating the cell environment directly in the second embodiment by notifying the cell radius d c and PMI feedback size Nfb from the base station to the terminal Similar effects can be obtained.
- the base station 10_5 includes a communication unit 101 for communicating with the terminal 20_5, a database 102, a beam angle range calculation unit 103, a beam angle interval calculation unit 104, a superset storage unit 150, a subset extraction unit 151, an index allocation unit 106, a code A book storage unit 107 and a control unit 108 are provided.
- the beam angle range calculation unit 103 and the beam angle interval calculation unit 104 generate beam angle information
- the superset storage unit 150, subset extraction unit 151, and index allocation unit 106 generate codebooks to be shared.
- the difference from the first embodiment is that a superset storage unit 150 and a subset extraction unit 151 are provided instead of the precoding matrix calculation unit 105.
- the database 102 stores cell environment information of a cell radius d c , a base station height h, and a PMI feedback size Nfb [bit].
- the beam angle range calculation unit 103 the beam angle range calculated by entering the cell radius d c and the base station height h from the database 102, the beam angle interval calculator 104 beam angle range from the beam angle range calculation unit 103
- the beam angle interval ⁇ is calculated using ⁇ r and the PMI feedback size Nfb from the database 102.
- the superset storage unit 150 stores a precoding matrix candidate group (superset) used in the codebook, as will be described later, and the subset extraction unit 151 stores the codebook precode from the superset according to the cell environment. Extract coding matrix group.
- a subset refers to a group of precoding matrices for use in a codebook selected from a superset.
- the index assigning unit 106 assigns a predetermined index to the extracted precoding matrix group for the codebook as in the first embodiment.
- the control unit 108 stores the precoding matrix group and the assigned index in the codebook storage unit 107 as a codebook.
- the control unit 108 executes communication control according to the present embodiment and controls the above-described functional units (101-104, 150, 151, 106, 107), and the beam angle range ⁇ r calculated by the beam angle range calculation unit 103. And the beam angle interval ⁇ calculated by the beam angle interval calculation unit 104 is transmitted to the terminal 20_5 as codebook determination information.
- the terminal 20_5 includes a communication unit 201, a superset storage unit 250, a subset extraction unit 251, an index allocation unit 203, a codebook storage unit 204, and a control unit 205 for communicating with the base station 10_5.
- a codebook to be shared by the superset storage unit 250, the subset extraction unit 251, and the index allocation unit 203 is generated.
- the superset storage unit 250 stores a precoding matrix candidate group (superset) used in the codebook, and the subset extraction unit 251 receives the codebook determination information received from the base station 10_5. Accordingly, a precoding matrix group for the codebook is extracted from the superset. Similar to the first embodiment, the index assigning unit 203 assigns a predetermined index to the extracted codebook precoding matrix group.
- the control unit 108 stores the precoding matrix group and the assigned index in the codebook storage unit 204 as a codebook.
- the superset storage unit (150, 250), subset extraction unit (151, 251), index allocation unit (106, 203) and codebook storage unit (107, 204) of the base station 10_5 and the terminal 20_5 are basically the same. Execute the process.
- FIG. 13 shows an example of a superset table stored in the superset storage unit 150.
- the superset is a group of precoding matrix candidates used in the codebook, and is composed of a precoding matrix V, an index corresponding thereto, and a beam angle ⁇ , and is sorted in ascending order of the beam angle ⁇ .
- Such a superset is calculated in advance and shared between the base station and the terminal. That is, they are stored in superset storage units 150 and 250 of base station 10_5 and terminal 20_5, respectively.
- the control unit 108 of the base station 10_5 reads out the cell radius d c , the base station height h, and the PMI feedback size Nfb, which are cell environment information of the base station 10_5, from the database 102 ( (Operation S110), the beam angle range calculation unit 103 and the beam angle interval calculation unit 104 are controlled to calculate the beam angle range ⁇ r and the beam angle interval ⁇ as in the first embodiment (Operation S111).
- the subset extraction unit 151 extracts a precoding matrix group for codebook from the superset using the calculated beam angle range ⁇ r and beam angle interval ⁇ (operation S161). Specifically, first, the beam angle group ⁇ i
- ⁇ super, j is a beam angle corresponding to the j-th precoding matrix in the superset
- ⁇ i is a beam angle corresponding to the i-th precoding matrix in the codebook.
- the precoding matrix for codebook can be determined by selecting the precoding matrix corresponding to each ⁇ cb, i thus obtained with reference to a super table as shown in FIG. If there are enough precoding matrices in the superset, and those that match ⁇ i are hit, the calculation of Equation (9) is not performed and the hit precoding matrix is directly sub-set (codebook). It can also be extracted as a precoding matrix.
- the index assigning unit 106 codes i for the precoding matrix group V i extracted by the subset extracting unit 151, as in the first embodiment. Allocation is performed as a book index (operation S122), and the allocation result is stored in the code book storage unit 107 (operation S123).
- control unit 108 transmits the code book determination information including the calculated beam angle range ⁇ r and the fixed beam angle interval ⁇ to the terminal 20_5 in the own cell through the communication unit 101. (Operation S124).
- the same cell-specific codebook stored in the codebook storage unit 107 of the base station 10_5 is stored in the codebook recording unit 204 of the terminal 20_5.
- the control unit 205 of the terminal 20_5 feeds back a code book index (PMI) as channel information to the base station 10_5.
- PMI code book index
- the cell-specific codebook is generated so as to satisfy the condition of the PMI feedback size Nfb.
- the codebook in addition to the effect of the first embodiment, can be generated only by the operation of extracting the codebook precoding matrix from the superset storage unit 150. There is an advantage that the calculation of the precoding matrix is not required and the processing load on the base station and the terminal is reduced.
- the beam angle interval ⁇ of the base station is previously stored in the database as a fixed value, so that the beam angle interval calculation unit can be omitted.
- the configuration and operation of the sixth embodiment will be described below.
- the configuration of the terminal 20_6 in the radio communication system according to the sixth embodiment of the present invention is the same as that of the terminal 20_5 in the fifth embodiment, so that the same reference numerals are used and description thereof is omitted.
- the base station 10_6 of this embodiment is partially different from the base station 10_5 of the fifth embodiment, the same reference numerals are assigned to the same blocks, and descriptions thereof are omitted, and only different components are described. To do.
- the base station 10_6 In the database 102b of the base station 10_6, in addition to the cell radius d c , the base station height h, and the PMI feedback size Nfb [bit], a fixed beam angle interval ⁇ indicating the cell environment of the base station 10_6 is stored. . Therefore, the base station 10_6 does not need the beam angle interval calculation unit 104 in the fifth embodiment.
- the other configuration is basically the same as that of the base station 10_5 of the fifth embodiment shown in FIG. 12, but the operation of the subset extracting unit 151 is partially different from that of the fifth embodiment.
- control unit 108 of the base station 10_6 When the base station is installed, the control unit 108 of the base station 10_6 generates a code book according to the procedure described below and stores it in the code book storage unit 107. Thereafter, regeneration may be performed at regular intervals or when the cell environment or system requirements are changed.
- the control unit 108 reads a cell radius d c , base station height h, PMI feedback size Nfb, and fixed value beam angle interval ⁇ , which are cell environment information of the base station 10_6, from the database 102b (operation S110b).
- the angle range calculation unit 103 is controlled to calculate the beam angle range ⁇ r (operation S111b). The specific calculation procedure is as described in the first embodiment.
- the subset extraction unit 151 extracts a precoding matrix group for the codebook from the superset using the calculated beam angle range ⁇ r and the read beam angle interval ⁇ that has been read (operation S161). ).
- 0 ⁇ i ⁇ satisfying the beam angle range ⁇ r and the beam angle interval ⁇ using the expressions (2) and (3). 2 Nfb ⁇ 1 ⁇ is calculated, and the beam angle ⁇ cb, i of the precoding matrix closest to each ⁇ i is selected from the superset using Equation (9).
- the precoding matrix for codebook can be determined by selecting the precoding matrix corresponding to each ⁇ cb, i thus obtained with reference to a super table as shown in FIG. If there are enough precoding matrices in the superset, and those that match ⁇ i are hit, the calculation of Equation (9) is not performed and the hit precoding matrix is directly sub-set (codebook). It can also be extracted as a precoding matrix.
- the index assigning unit 106 codes i for the precoding matrix group V i extracted by the subset extracting unit 151, as in the fifth embodiment. Allocation is performed as a book index (operation S122), and the allocation result is stored in the code book storage unit 107 (operation S123).
- the control unit 108 notifies the terminal 20_6 in the own cell through the communication unit 101 of code book determination information including the calculated beam angle range ⁇ r and a fixed beam angle interval ⁇ (operation S124).
- notification may be made using a broadcast channel (PBCH: Physical Broadcast CHannel) that notifies all terminals in the cell, or individually notified to a terminal that has made a connection request to the own cell. May be.
- PBCH Physical Broadcast CHannel
- the same cell-specific codebook stored in the codebook storage unit 107 of the base station 10_6 is stored in the codebook recording unit 204 of the terminal 20_6.
- the control unit 205 of the terminal 20_6 feeds back a code book index (PMI) as channel information to the base station 10_6.
- PMI code book index
- the cell-specific codebook is generated so as to satisfy the condition of the PMI feedback size Nfb.
- the beam angle interval processing unit can be omitted by setting the beam angle interval ⁇ to a fixed value.
- the point of generating a codebook from a high h and the cell radius d c a base station by the terminal side is notified is different from the fifth embodiment.
- the configuration and operation of the seventh embodiment will be described below.
- the control unit 205 of the terminal 20_7 When the terminal 20_7 receives the code book determining information (base station high h, cell radius d c and PMI feedback size Nfb), the control unit 205 of the terminal 20_7, like the operation S111 of the base station 10_7 side, beam angle range The calculation unit 252 and the beam angle interval calculation unit 253 are controlled to calculate the beam angle range ⁇ r and the beam angle interval ⁇ (operation S211). Subsequently, the control unit 205 controls the superset storage unit 250, the subset extraction unit 251 and the index allocation unit 203 to generate a codebook, similarly to the operations S161 and S122 to S123 on the base station 10_7 side.
- the subset extraction unit 251 extracts the precoding matrix group for the codebook from the superset using the calculated beam angle range ⁇ r and the read fixed beam angle interval ⁇ (operation S161). .
- 0 ⁇ i ⁇ satisfying the beam angle range ⁇ r and the beam angle interval ⁇ using the expressions (2) and (3). 2 Nfb ⁇ 1 ⁇ is calculated, and the beam angle ⁇ cb, i of the precoding matrix closest to each ⁇ i is selected from the superset using Equation (9).
- the precoding matrix for codebook can be determined by selecting the precoding matrix corresponding to each ⁇ cb, i thus obtained with reference to a super table as shown in FIG. If there are enough precoding matrices in the superset, and those that match ⁇ i are hit, the calculation of Equation (9) is not performed and the hit precoding matrix is directly sub-set (codebook). It can also be extracted as a precoding matrix.
- the index assigning unit 203 uses the codebook precoding matrix group V i extracted by the subset extraction unit 251 as in the fifth embodiment. Allocation as an index (operation S222), and the allocation result is stored in the codebook storage unit 204 (operation S223).
- the same cell-specific codebook stored in the codebook storage unit 107 of the base station 10_7 is stored in the codebook recording unit 204 of the terminal 20_7.
- the control unit 205 of the terminal 20_7 feeds back a code book index (PMI) as channel information to the base station 10_7.
- PMI code book index
- the cell-specific codebook is generated so as to satisfy the condition of the PMI feedback size Nfb.
- the beam angle interval ⁇ of the base station is stored in advance in the database as a fixed value as in the sixth embodiment. except a codebook from a radius d c and beam angle interval ⁇ is different from the sixth embodiment.
- the configuration and operation of the eighth embodiment will be described below.
- the configuration of the base station 10_8 in the eighth embodiment of the present invention is the same as that of the base station 10_6 in the sixth embodiment, so that the same reference numerals are used and description thereof is omitted.
- the terminal 20_7 of the present embodiment has a configuration in which a beam angle range calculation unit 252 is added to the base station 10_6 of the sixth embodiment, and other configurations are the same as those of the sixth embodiment.
- the same reference numerals are assigned and the description is omitted, and only different components will be described.
- the control unit 108 of the base station 10_8 generates a code book through operations S110b, S111b, S161, S122, and S123 and stores the code book in the code book storage unit 107, as in the sixth embodiment shown in FIG. Subsequently, the control unit 108 notifies the terminal 20_8 of the base station height h, the cell radius d c , the PMI feedback size Nfb, and the beam angle interval ⁇ read from the database 102b as codebook determination information (operation S124b).
- the control unit 205 of the terminal 20_8 calculates the beam angle range ⁇ r by controlling the beam angle range calculation unit 252 as in the operation S111b on the base station 10_8 side (operation S211b). Subsequently, similarly to the operations S161, S122, and S123 on the base station 10_8 side, the control unit 205 controls the superset storage unit 250, the subset extraction unit 251, and the index allocation unit 203 to generate a codebook, The data is stored in the recording unit 204 (operations S261, S222, and S223).
- the same cell-specific codebook stored in the codebook storage unit 107 of the base station 10_8 is stored in the codebook recording unit 204 of the terminal 20_8.
- the control unit 205 of the terminal 20_8 feeds back a code book index (PMI) as channel information to the base station 10_8.
- PMI code book index
- the cell-specific codebook is generated so as to satisfy the condition of the PMI feedback size Nfb.
- the codebook precoding matrix index is selected from the superset according to the cell environment, and the codebook is generated from the precoding matrix group of the selected index.
- the configuration and operation of the ninth embodiment will be described below.
- the base station 10_9 in the ninth embodiment of the present invention selects an index instead of the beam angle range calculation unit 103 and the beam angle interval calculation unit 104 on the base station side in the seventh embodiment.
- the unit 154 is replaced with an index selection unit 254 instead of the beam angle range calculation unit 252 and the beam angle interval calculation unit 253 on the terminal side.
- the database 102c of the base station 10_9 in addition to the information stored in the database 102 of the seventh embodiment, information on the 3 dB beam width of the vertical radiation pattern of the transmission beam generated by the base station 10_9 is held. Yes. That is, the database 102c stores the base station height h, the cell radius d c , the PMI feedback size Nfb, and the 3 dB beam width. Since the other configuration is the same as that of the seventh embodiment, the same reference numerals are assigned to the same blocks, and descriptions thereof are omitted.
- index selection units 154 and 254 calculate, as a limited index, an index corresponding to a precoding matrix that is not used in the codebook among the precoding matrices in the superset, and other supersets in the superset. The number is determined using the index as an unrestricted index. Since the index selectors 154 and 254 have the same functional configuration, index selection will be described below with reference to FIGS.
- the index selection units 154 and 254 have the same functional configuration, and include a metric calculation unit 901, an index restriction unit 902, and an unrestricted index number determination unit 903.
- index selection operation a single index limiting process of determining one precoding matrix based on a metric calculation of each precoding matrix in the superset and adding this to the limited index is performed as an unrestricted precoding matrix. (I.e., the number of precoding matrices used in the codebook) matches until the PMI feedback size Nfb requirement is met.
- the operation of the index selection unit will be described with reference to FIG.
- the metric calculating unit 901 the base station height h and cell radius d c from the database 102c, a superset from superset storage unit 150, a non-limiting index from the non-limiting index number determination section 903, and input respectively Then, a metric is calculated for each precoding matrix corresponding to the unrestricted index of the superset (operation S910).
- the metric calculation unit 901 calculates a metric again for the precoding matrix corresponding to the input unrestricted index. The metric calculation will be described later.
- the index restriction unit 902 determines one restriction index based on the metric value input from the metric calculation unit 901, and outputs it to the unrestricted index number determination unit 903 (operation S911).
- the non-restricted index number determination unit 903 determines whether or not the number of non-restricted indexes other than the limited index from the index limiting unit 902 satisfies the PMI feedback size Nfb requirement (within 2 Nfb ) (operation S912). . If the number of unrestricted indexes is 2 Nfb or less (operation S912; NO), the unrestricted PMI is output as a selection index to the subset extraction unit 151 (operation S913). Otherwise, the unrestricted index is a metric calculation unit 901. (Operation S912; YES).
- the metric calculation unit 901 calculates a metric from the beam angle corresponding to each index in the superset acquired from the superset storage unit 150. The metric calculation procedure will be described below.
- a beam coverage area is defined for each beam in the superset using a geometric model.
- an angle at which the attenuation from the peak gain of each beam is 3 dB is defined as a beam coverage area boundary angle, and an area irradiated with a beam having a higher gain is defined as a beam coverage area.
- the beam angle of the i-th beam is ⁇ i and the 3 dB attenuation angle in the vertical direction is ⁇ ⁇ , ⁇ + , [ ⁇ i + ⁇ ⁇ , ⁇ i + ⁇ + ] of the beam is irradiated.
- the area be the vertical beam coverage area.
- the beam coverage area may be calculated in consideration of the beam gain on the vertical plane and the horizontal plane at the same time.
- the sum of the overlapping areas of the beam coverage area between the own beam and the adjacent beam is calculated as a metric.
- adjacent means that an adjoining temporary index assigned in ascending order of the index in the superset with respect to an unrestricted index at the time of restriction processing with repeated index restriction processing.
- the metric calculation for the l-th beam coverage area in the temporary index in FIG. Since the area adjacent to the l-th beam coverage area is the (l-1) th and (l + 1) th area, the area of S high, l , S low, l as the overlapping area of the lth area and each adjacent area And the sum is taken as the metric. If there is only one adjacent beam coverage area located at the center of the cell or at the cell edge of the unrestricted index, the overlap area with that one adjacent beam coverage area is calculated and used as the metric. .
- the index restriction unit 902 sets an index in the superset corresponding to the index having the largest metric acquired from the metric calculation unit 901 as the restriction index. In other words, by removing the beam with the largest metric (here the largest overlapping area with adjacent areas), any PMI feedback while minimizing the coverage area reduction associated with the reduction of the precoding beam Can correspond to size.
- the non-restricted index number determination unit 903 calculates the number of non-restricted indexes from the limited index acquired from the index limiting unit 902, and compares the number and the total number (2 Nfb ) based on the PMI feedback size Nfb.
- the number of unrestricted indexes can be obtained by subtracting the number of restricted indexes from the total number of indexes in the superset. If the number of unrestricted indexes is 2 Nfb or less, the unrestricted index is output to the index assigning unit 106 and the process is terminated.
- an unrestricted index is output to the metric calculator 901, and the same processing as described above is repeated for the unrestricted index.
- the metric calculation unit 901 calculates a metric again for the precoding matrix corresponding to the input unrestricted index.
- the “adjacent beam coverage area” in the metric calculation is defined within the current unrestricted index. Therefore, the limited index has increased from the previous calculation, and the index included in the unrestricted index has changed. In this calculation, the temporary index is reassigned to the current unrestricted index group, and again the adjacent index. Calculate the metric after redefining the beam coverage area.
- the index restriction unit 902 repeats the same processing, and the non-restricted index number determination unit 903 combines the restriction index input from the index restriction unit 902 and the previously calculated restriction index into a new restriction index. Thereafter, similar processing is performed.
- the control unit 108 of the base station 10_9 reads the base station height h, the cell radius d c , the PMI feedback size Nfb, and the 3 dB beam width information from the database 102c (operation S110c), and the index selection unit 154 performs the above-described index selection ( Operation S171). Subsequently, the subset extraction unit 151 extracts a subset (codebook precoding matrix group) from the superset according to the selected index (operation S172).
- the index assigning unit 106 codes i for the precoding matrix group V i extracted by the subset extracting unit 151, as in the fifth embodiment. Allocation is performed as a book index (operation S122), and the allocation result is stored in the code book storage unit 107 (operation S123).
- the control unit 108 notifies the terminal 20_9 base station height h read from the database 102c, a cell radius d c and PMI feedback size Nfb as codebook determining information (operation S124b).
- the index selection unit 254 performs the above-described index selection as in the operation S171 on the base station 10_9 side (operation S271). Subsequently, the subset extraction unit 251 extracts a subset (codebook precoding matrix group) from the superset according to the selected index (operation S272). Subsequently, similarly to the operations S122 and S123 on the base station 10_9 side, the control unit 205 controls the index allocation unit 203 to generate a code book and stores it in the code book recording unit 204 (operations S222 and S223).
- the same cell-specific codebook stored in the codebook storage unit 107 of the base station 10_9 is stored in the codebook recording unit 204 of the terminal 20_9.
- the control unit 205 of the terminal 20_9 feeds back a code book index (PMI) as channel information to the base station 10_9.
- PMI code book index
- the cell-specific codebook is generated so as to satisfy the condition of the PMI feedback size Nfb.
- the codebook precoding matrix index is selected from the superset according to the cell environment, and the codebook is generated from the precoding matrix group of the selected index. Calculation of the beam angle range and beam angle interval is not necessary, and the processing load can be reduced. Furthermore, cell environment directly indicating the base station high h, it is possible to obtain the same effect as the fifth embodiment by notifying the cell radius d c and PMI feedback size Nfb from the base station to the terminal.
- Tenth Embodiment According to the tenth embodiment of the present invention, a plurality of codebooks corresponding to different cell environments are prepared in advance, and codebook selection information suitable for the cell environment of the base station is used for codebook determination. By notifying the terminal as information, a code book reflecting the cell environment of the base station is shared with the terminal.
- codebook selection information suitable for the cell environment of the base station is used for codebook determination.
- the base station 10_10 in the tenth embodiment of the present invention has a communication unit 101, a database 102, and a codebook storage for communicating with the terminal, as in the first embodiment.
- Unit 107 and control unit 108, and cell 102 stores cell environment information of cell radius d c , base station height h, and PMI feedback size Nfb [bit].
- the base station 10_10 is provided with a code book selection unit 160 and a code book candidate storage unit 161 as code book generation means.
- the code book candidate storage unit 161 includes a plurality of different code books CB # 1 to #n. Are stored in advance.
- a plurality of codebooks CB # 1 to #n are respectively stored in different cell parameters (cell radius d c , base station height) by the procedure described in the first to fourth embodiments (for example, operations S110 to S123 in FIG. 5). h).
- the terminal 20_10 is provided with a communication unit 201, a code book storage unit 204, and a control unit 205, and further stores the same code book # 1 to #n as the base station 10_10.
- a candidate storage unit 261 is provided.
- the codebook selection unit 160 reads the cell radius d c and the base station height h is a cell-specific parameter from the database 102 (operation S180), by using the cell-specific parameter
- the code book candidate storage unit 161 is searched, and the code book CB # i corresponding to the cell parameter that matches or is most similar to the cell specific parameter is selected (operation S181).
- the selected code book CB # i is stored in the code book storage unit 107 (operation S182).
- the control unit 108 notifies the terminal 20_10 of code book selection information for specifying the selected code book #i as code book determination information (operation S183).
- the control unit 205 of the terminal 20_10 Upon receiving the code book selection information, the control unit 205 of the terminal 20_10 reads out the code book CB # i specified by the code book selection information from the code book candidate storage unit 261 and stores it in the code book storage unit 204 (Operation S280).
- the selection of the code book is executed when the base station 10_10 is installed, and can be notified to the subordinate terminals. Thereafter, the codebook may be reselected at a fixed period or when the cell environment or system requirements are changed.
- the processing load on the base station and the terminal is reduced by selecting an appropriate one from a plurality of codebooks according to the cell environment of the base station.
- the same effects as those of the first embodiment described above can be obtained.
- a plurality of supersets corresponding to different cell environments are prepared in advance, and superset selection information and cell environment information suitable for the cell environment of the base station are provided. Is notified to the terminal as the code book determination information, the code book reflecting the cell environment of the base station can be shared with the terminal.
- the superset is as described in the fifth embodiment, and the codebook determination procedure using the selected superset is as described in the fifth to ninth embodiments. Is omitted.
- An example of a system configuration according to the eleventh embodiment is shown in FIG.
- the base station 10_11 in the eleventh embodiment of the present invention includes a communication unit 101, a database 102, a subset extraction unit 151, and an index allocation unit 106 for communicating with the terminal, as in the fifth embodiment.
- the code book storage unit 107 and the control unit 108 are provided, and the database 102 stores cell environment information of a cell radius d c , a base station height h, and a PMI feedback size Nfb [bit].
- the base station 10_11 is provided with a superset candidate storage unit 171 and a superset selection unit 172, and the superset candidate storage unit 171 stores a plurality of different supersets SS # 1 to SS # n in advance. .
- Each of the supersets SS # 1 to SS # n has a table configuration shown in FIG. 13, and the supersets SS # 1 to SS # n are generated corresponding to different cell environments. For example, if the base station is installed on a higher floor, if many buildings are planted around the base station, or if the surrounding cells are dense, avoid beam irradiation outside the cell coverage or cell coverage. In order to realize beam irradiation to a limited area, it is necessary to prepare a superset of precoding matrix groups that increase the beam angle in the vertical direction to some extent.
- the terminal 20_11 is provided with a communication unit 201, a subset extraction unit 251, an index allocation unit 203, a codebook storage unit 204, and a control unit 205, and a plurality of supersets that are the same as those of the base station 10_11
- a superset candidate storage unit 271 storing SS # 1 to SS # n is provided.
- the superset selection unit 172 reads the cell radius d c and the base station height h, which are cell specific parameters, from the database 102 (operation S180), and uses the cell specific parameters.
- the superset candidate storage unit 171 is searched, and the superset SS # i corresponding to the cell parameter that matches or is most similar to the cell-specific parameter is selected (operation S191).
- the codebook generated by the operations S161, S122, and S123 (see FIG. 14) in the fifth embodiment is stored in the codebook storage unit 107.
- the control unit 108 notifies the terminal 20_10 of the SS selection information that identifies the selected superset SS # i and the read cell-specific parameter information as codebook determination information (operation S192).
- the control unit 205 of the terminal 20_10 reads the superset SS # i specified by the SS selection information from the superset candidate storage unit 271 and uses this superset SS # i. Then, the operations S261, S222 and S223 described in the fifth embodiment are executed, and the determined codebook is stored in the codebook storage unit 204.
- the base stations and terminals in the first to eleventh embodiments described above are provided with a CPU (Central Processing Unit) or a computer for controlling their operations, and by executing a program stored in a memory (not shown), Functions similar to the above-described operations can be realized by software.
- a CPU Central Processing Unit
- a computer for controlling their operations, and by executing a program stored in a memory (not shown), Functions similar to the above-described operations can be realized by software.
- the present invention can be applied to a mobile communication system including a base station and a mobile station.
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Abstract
Description
本発明による端末装置は、コードブックを用いたプリコーディングによりビーム指向性制御を行う通信システムにおける端末装置であって、基地局から当該基地局のセル環境情報を含むコードブック決定用情報を受信する通信手段と、前記コードブック決定用情報に基づいて前記基地局と共通のコードブックを生成するコードブック生成手段と、を有することを特徴とする。
本発明による基地局装置は、コードブックを用いたプリコーディングによりビーム指向性制御を行う通信システムにおける基地局装置であって、当該基地局装置のセル環境情報を含むコードブック決定用情報を端末へ送信する通信手段と、前記コードブック決定用情報に基づいて前記端末と共通のコードブックを生成するコードブック生成手段と、を有することを特徴とする。
本発明によるコードブック共有方法は、基地局および端末に共通のコードブックを用いたプリコーディングによりビーム指向性制御を行う通信システムにおけるコードブック共有方法であって、前記基地局が当該基地局のセル環境情報を含むコードブック決定用情報を前記端末へ通知し、前記基地局および前記端末が前記コードブック決定用情報に基づいて共通のコードブックを生成する、ことを特徴とする。
本発明によるコードブック共有方法は、コードブックを用いたプリコーディングによりビーム指向性制御を行う通信システムにおけるコードブック共有方法であって、基地局から当該基地局のセル環境情報を含むコードブック決定用情報を受信し、前記コードブック決定用情報に基づいて前記基地局と共通のコードブックを生成する、ことを特徴とする。
本発明によるコードブック共有方法は、コードブックを用いたプリコーディングによりビーム指向性制御を行う通信システムにおけるコードブック共有方法であって、当該基地局のセル環境情報を含むコードブック決定用情報を端末へ送信し、前記コードブック決定用情報に基づいて前記端末と共通のコードブックを生成する、ことを特徴とする。
1.1)システム構成
図4において、本発明の第1実施例による無線通信システムにおける基地局10_1と端末20_1の構成は以下の通りである。
基地局10_1は、端末20_1と通信するための通信部101、データベース102、ビーム角レンジ計算部103、ビーム角間隔計算部104、プリコーディング行列計算部105、インデックス割当部106、コードブック記憶部107および制御部108を備える。後述するように、ビーム角レンジ計算部103およびビーム角間隔計算部104がビーム角情報を生成し、プリコーディング行列計算部105およびインデックス割当部106が共有すべきコードブックを生成する。
端末20_1は、基地局10_1と通信するための通信部201、プリコーディング行列計算部202、インデックス割当部203、コードブック記憶部204および制御部205を備える。後述するように、プリコーディング行列計算部202およびインデックス割当部203が共有すべきコードブックを生成する。
次に、図5を参照しながら、本実施例における基地局および端末の動作について説明する。
まず、制御部108は、データベース102から当該基地局10_1のセル環境情報であるセル半径dc、基地局高hおよびPMIフィードバックサイズNfbを読み出し(動作S110)、ビーム角レンジ計算部103およびビーム角間隔計算部104を制御してビーム角レンジφrおよびビーム角間隔Δφを計算する(動作S111)。具体的な計算手順は以下の通りである。
続いて、プリコーディング行列計算部105は、以下の計算手順により、ビーム角レンジφrとビーム角間隔Δφとに基づいて、当該ビーム角レンジおよびビーム角間隔を実現するコードブック用のプリコーディング行列群{V}を算出する(動作S121)。
次に、インデックス割当部106は、プリコーディング行列計算部105から取得したプリコーディング行列群Vi (i=0,1,・・・,2Nfb-1)に対してiをコードブックのインデックスとして割り当て(動作S122)、この割り当て結果がコードブック記憶部107に記憶される(動作S123)。
制御部108は、上述したビーム角レンジφrおよびビーム角間隔Δφからなるコードブック決定用情報を通信部101を通して自セル内の端末20_1に対して通知する(動作S124)。通知方法としては、セル内のすべての端末に対して通知する報知チャネル(PBCH:Physical Broadcast CHannel)を用いて通知してもよいし、自セルに接続要求をしてきた端末に対して個別に通知してもよい。
基地局10_1から通信部201を通してコードブック決定用情報を受信すると、端末20_1の制御部205は、基地局10_1側の動作S121~S123と同様に、プリコーディング行列計算部202およびインデックス割当部203を制御してコードブックを生成する。すなわち、プリコーディング行列計算部202は、受信したビーム角レンジφrおよびビーム角間隔Δφを用い、上述した式(3)~式(7)に従って当該ビーム角レンジおよびビーム角間隔を実現するコードブック用のプリコーディング行列群{V}を算出する(動作S221)。続いて、インデックス割当部203は、算出されたプリコーディング行列群Vi (i=0,1,・・・,2Nfb-1)に対してiをコードブックのインデックスとして割り当てる(動作S222)。制御部205は、割り当て結果をコードブック記憶部204に記憶する(動作S223)。
上述したように、本発明の第1実施例によれば、セル環境に応じて計算したビーム角レンジφrおよびビーム角間隔Δφを基地局10_1から端末20_1に通知することで、同様の処理により基地局と端末との間でセル環境を反映したコードブックを共有することができる。すなわち、無駄なプリコーディング行列のないセル環境に適し、かつ、PMIフィードバック条件を満たす必要最低限のコードブックを基地局-端末間で共有することができ、システム容量の改善が可能となる。
本発明の第2実施例によれば、基地局のビーム角間隔Δφを固定値としてデータベースに予め格納しておき、それによりビーム角間隔計算部を省略することができる。以下、第2実施例の構成および動作について説明する。
2.1)システム構成
図6において、本発明の第2実施例による無線通信システムにおける端末20_2の構成は第1実施例における端末20_1と同じであるから同一参照番号を付して説明は省略する。本実施例の基地局10_2は、第1実施例の基地局10_1と部分的な構成が異なっているので、同一ブロックには同一の参照番号を付して説明は省略し、異なる構成部分のみ説明する。
次に、図7を参照しながら、本実施例における基地局および端末の動作について説明する。
まず、制御部108は、データベース102bから当該基地局10_2のセル環境情報であるセル半径dc、基地局高h、PMIフィードバックサイズNfbおよび固定値のビーム角間隔Δφを読み出し(動作S110b)、ビーム角レンジ計算部103を制御してビーム角レンジφrを計算する(動作S111b)。具体的な計算手順は第1実施例で説明した通りである。
続いて、プリコーディング行列計算部105bは、第1実施例で説明した計算手順により、計算されたビーム角レンジφrとデータベース102bから読み出された固定値のビーム角間隔Δφとに基づいて、当該ビーム角レンジおよびビーム角間隔を実現するコードブック用のプリコーディング行列群{V}を算出する(動作S121b)。ただし、ビーム角間隔Δφが固定値であるから、プリコーディング行列計算部105bは、PMIフィードバックサイズNfbの条件を満たすようにコードブックの一部を制限する制御を実行する。この点が第1実施例と異なっているので、以下、この相違点を中心に説明し、その他の動作は第1実施例と同様であるから詳細は省略する。
制御部108は、計算されたビーム角レンジφrと固定値のビーム角間隔Δφからなるコードブック決定用情報を通信部101を通して自セル内の端末20_2に対して通知する(動作S124)。通知方法としては、セル内のすべての端末に対して通知する報知チャネル(PBCH:Physical Broadcast CHannel)を用いて通知してもよいし、自セルに接続要求をしてきた端末に対して個別に通知してもよい。
基地局10_2から通信部201を通してコードブック決定用情報を受信すると、端末20_2の制御部205は、基地局10_2側の動作S121b、S122、S123と同様に、プリコーディング行列計算部202およびインデックス割当部203を制御してコードブックを生成しコードブック記憶部204に格納する(動作S221b、S222、S223)。その際、プリコーディング行列計算部202は、基地局側の動作S121bと同様に、PMIフィードバックサイズNfbの条件を満たすようにコードブックの一部を制限する制御を実行する。
本発明の第2実施例によれば、第1実施例の効果に加えて、ビーム角間隔Δφを固定値にすることでビーム角間隔処理部を省略することができ、基地局の装置構成を簡略化できるという利点がある。
本発明の第3実施例によれば、端末側が通知された基地局高hとセル半径dcからコードブックを生成する点が第1実施例とは異なっている。以下、第3実施例の構成および動作について説明する。
図8において、本発明の第3実施例における基地局10_3の構成は第1実施例における基地局10_1と同じであるから同一参照番号を付して説明は省略するが、基地局10_3が端末20_3に対して基地局高h、セル半径dcおよびPMIフィードバックサイズNfbからなるコードブック決定用情報を通知する点が異なっている。したがって、本実施例の端末20_3には、第1実施例の端末20_1の構成にビーム角レンジ計算部206およびビーム角間隔計算部207が追加されている。その他の構成は第1実施例と同様であるから、第1実施例と同一のブロックには同一の参照番号を付し、第1実施例と異なる動作について主に説明する。
図9において、基地局10_3の動作S110~S123は第1実施例と同じであるが、制御部108は、データベース102から読み出した基地局高h、セル半径dcおよびPMIフィードバックサイズNfbをコードブック決定用情報として端末20_3へ通知する(動作S124b)。
本発明の第3実施例によれば、セル環境を直接示す基地局高h、セル半径dcおよびPMIフィードバックサイズNfbを基地局から端末へ通知することで第1実施例と同様の効果を得ることができる。
本発明の第4実施例によれば、第2実施例と同様に基地局のビーム角間隔Δφが固定値としてデータベースに予め格納されているが、端末が基地局高h、セル半径dcおよびビーム角間隔Δφからコードブックを生成する点が第2実施例とは異なっている。以下、第4実施例の構成および動作について説明する。
4.1)システム構成
図10において、本発明の第4実施例における基地局10_4の構成は第2実施例における基地局10_2と同じであるから同一参照番号を付して説明は省略する。本実施例の端末20_4は、第2実施例の基地局10_2にビーム角レンジ計算部206が追加された構成を有し、他の構成は第2実施例と同様であるから、同一ブロックには同一の参照番号を付して説明は省略し、異なる構成部分のみ説明する。
次に、図11を参照しながら、本実施例における基地局および端末の動作について説明する。
本発明の第4実施例によれば、セル環境を直接示す基地局高h、セル半径dcおよびPMIフィードバックサイズNfbを基地局から端末へ通知することで第2実施例と同様の効果を得ることができる。
5.1)システム構成
図12において、本発明の第5実施例による無線通信システムにおける基地局10_5と端末20_5の構成は以下の通りである。
基地局10_5は、端末20_5と通信するための通信部101、データベース102、ビーム角レンジ計算部103、ビーム角間隔計算部104、スーパーセット記憶部150、サブセット抽出部151、インデックス割当部106、コードブック記憶部107および制御部108を備える。後述するように、ビーム角レンジ計算部103およびビーム角間隔計算部104がビーム角情報を生成し、スーパーセット記憶部150、サブセット抽出部151およびインデックス割当部106が共有すべきコードブックを生成する。第1実施例との相違は、プリコーディング行列計算部105の代わりに、スーパーセット記憶部150およびサブセット抽出部151を設けた点である。
端末20_5は、基地局10_5と通信するための通信部201、スーパーセット記憶部250、サブセット抽出部251、インデックス割当部203、コードブック記憶部204および制御部205を備える。後述するように、スーパーセット記憶部250、サブセット抽出部251およびインデックス割当部203が共有すべきコードブックを生成する。
図13において、スーパーセット記憶部150に格納されたスーパーセットテーブルの一例を示す。スーパーセットはコードブックで用いられるプリコーディング行列の候補群であり、プリコーディング行列Vとそれに対応するインデックスおよびビーム角φで構成され、ビーム角φの昇順にソートされている。なお、スーパーセット内のj番目のプリコーディング行列Vj =[1 exp(jpj)]Tに対応するビーム角φjは次式(8)で計算される。
図14において、まず、基地局10_5の制御部108は、データベース102から当該基地局10_5のセル環境情報であるセル半径dc、基地局高hおよびPMIフィードバックサイズNfbを読み出し(動作S110)、ビーム角レンジ計算部103およびビーム角間隔計算部104を制御して、第1実施例と同様にビーム角レンジφrおよびビーム角間隔Δφを計算する(動作S111)。
続いて、サブセット抽出部151は、計算されたビーム角レンジφrおよびビーム角間隔Δφを用いて、スーパーセットからコードブック用のプリコーディング行列群を抽出する(動作S161)。具体的には、まず、既に述べた式(2)および式(3)を用いて、ビーム角レンジφrおよびビーム角間隔Δφを満たすビーム角群{φi|0≦i≦2Nfb-1}を算出する。次に、次式(9)を用いて、スーパーセットから各φiに最も近いプリコーディング行列のビーム角φcb,iを選択する。
また、制御部108は、第1実施例と同様に、計算されたビーム角レンジφrと固定値のビーム角間隔Δφからなるコードブック決定用情報を通信部101を通して自セル内の端末20_5に対して通知する(動作S124)。
基地局10_5から通信部201を通してコードブック決定用情報を受信すると、端末20_5の制御部205は、基地局10_5側の動作S161、S122、S123と同様に、スーパーセット記憶部250、サブセット抽出部251およびインデックス割当部203を制御してコードブック用のサブセットをコードブック記憶部204に格納する(動作S261、S222、S223)。
本発明の第5実施例によれば、第1実施例の効果に加えて、スーパーセット記憶部150からコードブック用プリコーディング行列を抽出する動作だけでコードブックを生成できるので、プリコーディング行列の計算が不要となり、基地局および端末の処理負荷が軽減されるという利点がある。
本発明の第6実施例によれば、基地局のビーム角間隔Δφを固定値としてデータベースに予め格納しておき、それによりビーム角間隔計算部を省略することができる。以下、第6実施例の構成および動作について説明する。
6.1)システム構成
図15において、本発明の第6実施例による無線通信システムにおける端末20_6の構成は第5実施例における端末20_5と同じであるから同一参照番号を付して説明は省略する。本実施例の基地局10_6は、第5実施例の基地局10_5と部分的な構成が異なっているので、同一ブロックには同一の参照番号を付して説明は省略し、異なる構成部分のみ説明する。
次に、図16を参照しながら、本実施例における基地局および端末の動作について説明する。
まず、制御部108は、データベース102bから当該基地局10_6のセル環境情報であるセル半径dc、基地局高h、PMIフィードバックサイズNfbおよび固定値のビーム角間隔Δφを読み出し(動作S110b)、ビーム角レンジ計算部103を制御してビーム角レンジφrを計算する(動作S111b)。具体的な計算手順は第1実施例で説明した通りである。
続いて、サブセット抽出部151は、計算されたビーム角レンジφrと読み出された固定値のビーム角間隔Δφとを用いて、スーパーセットからコードブック用のプリコーディング行列群を抽出する(動作S161)。具体的には、第5実施例で述べたように、式(2)および式(3)を用いて、ビーム角レンジφrおよびビーム角間隔Δφを満たすビーム角群{φi|0≦i≦2Nfb-1}を算出し、式(9)を用いてスーパーセットから各φiに最も近いプリコーディング行列のビーム角φcb,iを選択する。
制御部108は、計算されたビーム角レンジφrと固定値のビーム角間隔Δφからなるコードブック決定用情報を通信部101を通して自セル内の端末20_6に対して通知する(動作S124)。通知方法としては、セル内のすべての端末に対して通知する報知チャネル(PBCH:Physical Broadcast CHannel)を用いて通知してもよいし、自セルに接続要求をしてきた端末に対して個別に通知してもよい。
基地局10_6から通信部201を通してコードブック決定用情報を受信すると、端末20_6の制御部205は、基地局10_6側の動作S161、S122、S123と同様に、スーパーセット記憶部250、サブセット抽出部251およびインデックス割当部203を制御してコードブック用のサブセットをコードブック記憶部204に格納する(動作S261、S222、S223)。
本発明の第6実施例によれば、第5実施例の効果に加えて、ビーム角間隔Δφを固定値にすることでビーム角間隔処理部を省略することができ、基地局の装置構成を簡略化できるという利点がある。
本発明の第7実施例によれば、端末側が通知された基地局高hとセル半径dcからコードブックを生成する点が第5実施例とは異なっている。以下、第7実施例の構成および動作について説明する。
図17において、本発明の第7実施例における基地局10_7の構成は第5実施例における基地局10_5と同じであるから同一参照番号を付して説明は省略するが、基地局10_7が端末20_7に対して基地局高h、セル半径dcおよびPMIフィードバックサイズNfbからなるコードブック決定用情報を通知する点が異なっている。したがって、本実施例の端末20_7には、第5実施例の端末20_5の構成にビーム角レンジ計算部252およびビーム角間隔計算部253が追加されている。その他の構成は第5実施例と同様であるから、第5実施例と同一のブロックには同一の参照番号を付し、第5実施例と異なる動作について主に説明する。
図18において、基地局10_7の動作S110、S111、S161、S122およびS123は第5実施例と同じであるが、制御部108は、データベース102から読み出した基地局高h、セル半径dcおよびPMIフィードバックサイズNfbをコードブック決定用情報として端末20_7へ通知する(動作S124b)。
本発明の第7実施例によれば、セル環境を直接示す基地局高h、セル半径dcおよびPMIフィードバックサイズNfbを基地局から端末へ通知することで第5実施例と同様の効果を得ることができる。
本発明の第8実施例によれば、第6実施例と同様に基地局のビーム角間隔Δφが固定値としてデータベースに予め格納されているが、端末が基地局高h、セル半径dcおよびビーム角間隔Δφからコードブックを生成する点が第6実施例とは異なっている。以下、第8実施例の構成および動作について説明する。
図19において、本発明の第8実施例における基地局10_8の構成は第6実施例における基地局10_6と同じであるから同一参照番号を付して説明は省略する。本実施例の端末20_7は、第6実施例の基地局10_6にビーム角レンジ計算部252が追加された構成を有し、他の構成は第6実施例と同様であるから、同一ブロックには同一の参照番号を付して説明は省略し、異なる構成部分のみ説明する。
次に、図20を参照しながら、本実施例における基地局および端末の動作について説明する。
本発明の第8実施例によれば、セル環境を直接示す基地局高h、セル半径dcおよびPMIフィードバックサイズNfbを基地局から端末へ通知することで第5実施例と同様の効果を得ることができる。
本発明の第9実施例によれば、セル環境に従ってスーパーセットからコードブック用プリコーディング行列のインデックスを選択し、選択されたインデックスのプリコーディング行列群からコードブックを生成する。以下、第9実施例の構成および動作について説明する。
図21において、本発明の第9実施例における基地局10_9は、第7実施例における基地局側のビーム角レンジ計算部103およびビーム角間隔計算部104の代わりにインデックス選択部154を、端末側のビーム角レンジ計算部252およびビーム角間隔計算部253の代わりにインデックス選択部254を、それぞれ置き換えた構成を有する。
インデックス選択部154および254は、スーパーセット内のプリコーディング行列のうちコードブック内で用いないプリコーディング行列に対応するインデックスを制限インデックスとして算出し、それ以外のスーパーセット内のインデックスを非制限インデックスとして個数判定を行う。インデックス選択部154および254は同一の機能構成を有するので、以下、図22~図26を参照しながらインデックス選択について説明する。
メトリック計算部901はスーパーセット記憶部150から取得したスーパーセット内の各インデックスに対応するビーム角からメトリックの計算を行う。以下、メトリックの計算手順について説明する。
インデックス制限部902は、メトリック計算部901から取得したメトリックが最も大きいインデックスに対応するスーパーセット内でのインデックスを制限インデックスとする。言い換えれば、最もメトリックが大きい(ここでは隣接エリアとの重複面積が最大の)ビームを削除することで、プリコーディング用ビームの減少に伴うカバレッジエリアの減少を最小限に抑えつつ、任意のPMIフィードバックサイズに対応することができる。
非制限インデックス数判定部903は、インデックス制限部902から取得した制限インデックスから非制限インデックスの個数を計算し、その個数とPMIフィードバックサイズNfbに基づく総数(2Nfb)の大小を比較する。ここで、非制限インデックスの個数はスーパーセット内のインデックスの総数から制限インデックスの個数を差し引くことで求められる。非制限インデックスの個数が、2Nfb以下であれば、非制限インデックスをインデックス割当部106に出力し処理を終了する。その他の場合は、非制限インデックスをメトリック計算部901へ出力し、当該非制限インデックスに対して上述と同様の処理が繰り返される。非制限インデックス数判定部903から非制限インデックスが出力された場合、メトリック計算部901は入力された非制限インデックスに対応するプリコーディング行列に対して再度メトリックの計算を行う。
次に、図27を参照しながら、本実施例における基地局および端末の動作について説明する。
本発明の第9実施例によれば、セル環境に従ってスーパーセットからコードブック用プリコーディング行列のインデックスを選択し、選択されたインデックスのプリコーディング行列群からコードブックを生成するので、ビーム角レンジやビーム角間隔などの計算が不要となり、処理負荷を軽減することができる。さらに、セル環境を直接示す基地局高h、セル半径dcおよびPMIフィードバックサイズNfbを基地局から端末へ通知することで第5実施例と同様の効果を得ることができる。
本発明の第10実施例によれば、それぞれ異なるセル環境に対応した複数のコードブックを予め用意しておき、基地局のセル環境に適したコードブック選択情報をコードブック決定用情報として端末に通知することで、当該基地局のセル環境を反映したコードブックを端末との間で共有する。以下、第10実施例の構成および動作について説明する。
図28において、本発明の第10実施例における基地局10_10には、第1実施例と同様に、端末との通信を行うための通信部101、データベース102、コードブック記憶部107および制御部108が設けられ、データベース102にはセル半径dc、基地局高hおよびPMIフィードバックサイズNfb[bit]のセル環境情報が格納されている。さらに、基地局10_10には、コードブック生成手段として、コードブック選択部160とコードブック候補記憶部161とが設けられ、コードブック候補記憶部161には異なる複数のコードブックCB#1~#nが予め格納されている。複数のコードブックCB#1~#nは、上述した第1~第4実施例で説明した手順(たとえば図5の動作S110~S123)により、それぞれ異なるセルパラメータ(セル半径dc、基地局高h)に対応して生成される。
図29に示すように、コードブック選択部160は、データベース102からセル固有パラメータであるセル半径dcおよび基地局高hを読み出し(動作S180)、当該セル固有パラメータを用いてコードブック候補記憶部161を検索し、一致したあるいは当該セル固有パラメータに最も類似したセルパラメータに対応するコードブックCB#iを選択する(動作S181)。選択されたコードブックCB#iはコードブック記憶部107に格納される(動作S182)。続いて、制御部108は、選択されたコードブック#iを特定するコードブック選択情報をコードブック決定用情報として端末20_10へ通知する(動作S183)。
本発明の第10実施例によれば、基地局のセル環境に合わせて複数のコードブックから適切な1つを選択することで、基地局および端末の処理負荷を軽減しつつ上述した第1実施例と同様の効果を得ることができる。
本発明の第11実施例によれば、それぞれ異なるセル環境に対応した複数のスーパーセットを予め用意しておき、基地局のセル環境に適したスーパーセット選択情報とセル環境情報とをコードブック決定用情報として端末に通知することで、当該基地局のセル環境を反映したコードブックを端末との間で共有することもできる。なお、スーパーセットについては第5実施例で説明したとおりであり、また、選択されたスーパーセットを用いたコードブック決定手順は第5~第9実施例で述べたとおりであるから、これらの説明は省略する。第11実施例によるシステム構成の一例を図30に示す。
図31に示すように、スーパーセット選択部172は、データベース102からセル固有パラメータであるセル半径dcおよび基地局高hを読み出し(動作S180)、当該セル固有パラメータを用いてスーパーセット候補記憶部171を検索し、一致したあるいは当該セル固有パラメータに最も類似したセルパラメータに対応するスーパーセットSS#iを選択する(動作S191)。以下、第5実施例における動作S161、S122およびS123(図14参照)により生成されたコードブックがコードブック記憶部107に格納される。続いて、制御部108は、選択されたスーパーセットSS#iを特定するSS選択情報および読み出されたセル固有パラメータ情報をコードブック決定用情報として端末20_10へ通知する(動作S192)。
本発明の第11実施例によれば、基地局のセル環境に合わせて複数のスーパーセットから適切な1つを選択することで、より柔軟に環境に対応することが可能となる。
上述した第1~第11実施例における基地局および端末には、それぞれの動作を制御するCPU(Central Processing Unit)あるいはコンピュータが設けられ、図示しないメモリに格納されたプログラムを実行することにより、それぞれの上記動作と同様の機能をソフトウエアで実現することも可能である。
20、20_1~20_11 端末
101 通信部
102 データベース
103 ビーム角レンジ計算部
104 ビーム角間隔計算部
105 プリコーディング行列計算部
106 インデックス割当部
107 コードブック記憶部
108 制御部
150 スーパーセット記憶部
151 サブセット抽出部
154 インデックス選択部
160 コードブック選択部
161 コードブック候補記憶部
171 スーパーセット候補記憶部
172 スーパーセット選択部
201 通信部
202 プリコーディング行列計算部
203 インデックス割当部
204 コードブック記憶部
205 制御部
250 スーパーセット記憶部
251 サブセット抽出部
254 インデックス選択部
261 コードブック候補記憶部
271 スーパーセット候補記憶部
Claims (25)
- 基地局および端末に共通のコードブックを用いたプリコーディングによりビーム指向性制御を行う通信システムであって、
前記基地局が当該基地局のセル環境情報を含むコードブック決定用情報を前記端末へ通知し、
前記基地局および前記端末が前記コードブック決定用情報に基づいて共通のコードブックを生成する、
ことを特徴とする通信システム。 - コードブックを用いたプリコーディングによりビーム指向性制御を行う通信システムにおける端末装置であって、
基地局から当該基地局のセル環境情報を含むコードブック決定用情報を受信する通信手段と、
前記コードブック決定用情報に基づいて前記基地局と共通のコードブックを生成するコードブック生成手段と、
を有することを特徴とする端末装置。 - 前記セル環境情報は前記基地局のセル面からの高さと前記基地局からセル端までのセル面上の距離とを含むセル固有情報に依存する情報であることを特徴とする請求項2に記載の端末装置。
- 前記コードブック生成手段は、前記セル環境情報に依存するビーム角に関する情報に基づいて前記コードブック用のプリコーディング行列を算出することを特徴とする請求項2または3に記載の端末装置。
- 前記コードブック生成手段は、前記セル環境情報から前記ビーム角に関する情報を算出することを特徴とする請求項4に記載の端末装置。
- 前記コードブック生成手段は、
複数のプリコーディング行列候補を格納した記憶手段と、
前記セル環境情報を用いて前記記憶手段から前記コードブック用のプリコーディング行列を抽出する抽出手段と、
を有することを特徴とする請求項2または3に記載の端末装置。 - 前記コードブック生成手段は、前記セル環境情報から前記ビーム角に関する情報を計算する計算手段を更に有し、前記抽出手段は、前記ビーム角に関する情報を用いて前記記憶手段から前記コードブック用のプリコーディング行列を抽出することを特徴とする請求項6に記載の端末装置。
- 前記コードブック生成手段は、
複数のプリコーディング行列候補をビーム角に関する情報に従って格納した記憶手段と、
前記セル環境情報を用いて他のビームとのカバレッジエリアの重なりを計算する計算手段と、
前記カバレッジエリアの重なりが大きい順に当該ビームに対応するプリコーディング行列を削除することで所定数のプリコーディング行列からなる前記コードブックを生成する選択手段と、
を有することを特徴とする請求項2または3に記載の端末装置。 - 前記コードブック生成手段は、
複数の異なるプリコーディング行列群をコードブック用のプリコーディング行列候補として格納した記憶手段と、
前記基地局から当該基地局が選択したプリコーディング行列群を特定する情報を含むコードブック決定用情報を受信すると、当該選択されたプリコーディング行列群を前記基地局との通信のためのコードブックとして格納する制御手段と、
を有することを特徴とする請求項2または3に記載の端末装置。 - 前記コードブック生成手段は、
複数のセル環境にそれぞれ対応する複数のプリコーディング行列群をプリコーディング行列群候補として格納した記憶手段と、
前記基地局から当該基地局が選択したプリコーディング行列群候補を特定する情報を含むコードブック決定用情報を受信すると、当該選択されたプリコーディング行列群候補から所定数のプリコーディング行列を選択し、前記基地局との通信のためのコードブックとして格納する制御手段と、
を有することを特徴とする請求項2または3に記載の端末装置。 - コードブックを用いたプリコーディングによりビーム指向性制御を行う通信システムにおける基地局装置であって、
当該基地局装置のセル環境情報を含むコードブック決定用情報を端末へ送信する通信手段と、
前記コードブック決定用情報に基づいて前記端末と共通のコードブックを生成するコードブック生成手段と、
を有することを特徴とする基地局装置。 - 前記セル環境情報は前記基地局のセル面からの高さと前記基地局からセル端までのセル面上の距離とを含むセル固有情報に依存する情報であることを特徴とする請求項11に記載の基地局装置。
- 前記コードブック生成手段は、前記セル環境情報に依存するビーム角に関する情報に基づいて前記コードブック用のプリコーディング行列を算出することを特徴とする請求項11または12に記載の基地局装置。
- 前記コードブック生成手段は、前記セル環境情報から前記ビーム角に関する情報を算出することを特徴とする請求項13に記載の基地局装置。
- 前記コードブック生成手段は、
複数のプリコーディング行列候補を格納した記憶手段と、
前記セル環境情報を用いて前記記憶手段から前記コードブック用のプリコーディング行列を抽出する抽出手段と、
を有することを特徴とする請求項11または12に記載の基地局装置。 - 前記コードブック生成手段は、前記セル環境情報から前記ビーム角に関する情報を計算する計算手段を更に有し、前記抽出手段は、前記ビーム角に関する情報を用いて前記記憶手段から前記コードブック用のプリコーディング行列を抽出することを特徴とする請求項15に記載の基地局装置。
- 前記コードブック生成手段は、
複数のプリコーディング行列候補をビーム角に関する情報に従って格納した記憶手段と、
前記セル環境情報を用いて他のビームとのカバレッジエリアの重なりを計算する計算手段と、
前記カバレッジエリアの重なりが大きい順に当該ビームに対応するプリコーディング行列を削除することで所定数のプリコーディング行列からなる前記コードブックを生成する選択手段と、
を有することを特徴とする請求項11または12に記載の基地局装置。 - 前記コードブック生成手段は、
複数の異なるプリコーディング行列群をコードブック用のプリコーディング行列候補として格納した記憶手段と、
前記セル固有情報に基づいて前記プリコーディング行列候補からプリコーディング行列群を選択する選択手段と、
を有し、前記コードブック決定用情報を前記選択したプリコーディング行列群を特定する情報を含めて前記端末へ送信することを特徴とする請求項11または12に記載の基地局装置。 - 前記コードブック生成手段は、
複数のセル環境にそれぞれ対応する複数のプリコーディング行列群をプリコーディング行列群候補として格納した記憶手段と、
前記セル固有情報に基づいてプリコーディング行列群候補を選択する選択手段と、
を有し、前記コードブック決定用情報を前記選択したプリコーディング行列群候補を特定する情報を含めて前記端末へ送信することを特徴とする請求項11または12に記載の基地局装置。 - 基地局および端末に共通のコードブックを用いたプリコーディングによりビーム指向性制御を行う通信システムにおけるコードブック共有方法であって、
前記基地局が当該基地局のセル環境情報を含むコードブック決定用情報を前記端末へ通知し、
前記基地局および前記端末が前記コードブック決定用情報に基づいて共通のコードブックを生成する、
ことを特徴とするコードブック共有方法。 - コードブックを用いたプリコーディングによりビーム指向性制御を行う通信システムにおける無線通信装置のコードブック共有方法であって、
基地局から当該基地局のセル環境情報を含むコードブック決定用情報を受信し、
前記コードブック決定用情報に基づいて前記基地局と共通のコードブックを生成する、
ことを特徴とするコードブック共有方法。 - コードブックを用いたプリコーディングによりビーム指向性制御を行う通信システムにおける無線通信装置のコードブック共有方法であって、
当該無線通信装置のセル環境情報を含むコードブック決定用情報を無線端末へ送信し、
前記コードブック決定用情報に基づいて前記無線端末と共通のコードブックを生成する、
ことを特徴とするコードブック共有方法。 - 基地局と端末で共通のコードブックを用いてプリコーディングを使った垂直面のビーム指向性制御を伴う通信システムにおけるコードブック共有方法において、
前記基地局がビーム角レンジとビーム角間隔からなるセル固有パラメータをコードブック決定用情報として前記端末に通知し、
前記基地局および前記端末が、前記セル固有パラメータに基づいて計算されたプリコーディング行列を用いて前記共通のコードブックを生成する、
ことを特徴とするコードブック共有方法。 - コードブックを用いたプリコーディングによりビーム指向性制御を行う通信システムにおける無線通信装置としてコンピュータを機能させるプログラムであって、
基地局から当該基地局のセル環境情報を含むコードブック決定用情報を受信する機能と、
前記コードブック決定用情報に基づいて前記基地局と共通のコードブックを生成する機能と、
を前記コンピュータで実現することを特徴とするプログラム。 - コードブックを用いたプリコーディングによりビーム指向性制御を行う通信システムにおける無線通信装置としてコンピュータを機能させるプログラムであって、
当該無線通信装置のセル環境情報を含むコードブック決定用情報を無線端末へ送信する機能と、
前記コードブック決定用情報に基づいて前記無線端末と共通のコードブックを生成する機能と、
を前記コンピュータで実現することを特徴とするプログラム。
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JPWO2014119276A1 (ja) | 2017-01-26 |
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