WO2016021013A1 - Système de communication sans fil, station de base, station mobile, procédé d'émission et procédé d'estimation - Google Patents

Système de communication sans fil, station de base, station mobile, procédé d'émission et procédé d'estimation Download PDF

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Publication number
WO2016021013A1
WO2016021013A1 PCT/JP2014/070792 JP2014070792W WO2016021013A1 WO 2016021013 A1 WO2016021013 A1 WO 2016021013A1 JP 2014070792 W JP2014070792 W JP 2014070792W WO 2016021013 A1 WO2016021013 A1 WO 2016021013A1
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antenna
antennas
reference signal
mobile station
communication system
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PCT/JP2014/070792
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English (en)
Japanese (ja)
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大介 実川
田中　良紀
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富士通株式会社
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Priority to PCT/JP2014/070792 priority Critical patent/WO2016021013A1/fr
Publication of WO2016021013A1 publication Critical patent/WO2016021013A1/fr

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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
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04J—MULTIPLEX COMMUNICATION
    • H04J11/00—Orthogonal multiplex systems, e.g. using WALSH codes

Definitions

  • the present invention relates to a radio communication system, a base station, a mobile station, a transmission method, and an estimation method.
  • Non-Patent Document 1 Long Term Evolution
  • MIMO Multiple Input Multiple Output
  • 3D Channel Model in the standardization of LTE Release 12 has been studied (for example, see Non-Patent Document 2 below).
  • reference signals for estimating the channel state on the receiving side are transmitted from all antennas. Therefore, when the number of antennas is increased, radio resources used for transmitting the reference signals increase. There is a problem.
  • an object of the present invention is to suppress an increase in radio resources used for transmitting a reference signal.
  • a reference signal is transmitted by a second antenna disposed at a position in the second direction with respect to one antenna, and the antenna group is based on the reference signals transmitted by the plurality of antennas and the second antenna.
  • a wireless communication system, a base station, a mobile station, a transmission method, and an estimation method are proposed that estimate channel states of antennas different from the plurality of antennas and the second antenna.
  • FIG. 1 is an explanatory diagram illustrating an example of a functional configuration of a wireless communication system.
  • FIG. 2 is an explanatory diagram illustrating an example of a configuration of a wireless communication system.
  • FIG. 3 is a sequence diagram illustrating an example of a processing procedure between apparatuses performed by the wireless communication system.
  • FIG. 4 is a functional block diagram illustrating an example of an eNB.
  • FIG. 5 is a functional block diagram illustrating an example of a mobile station.
  • FIG. 6 is an explanatory diagram illustrating an example of a transmission antenna of the eNB.
  • FIG. 7 is an explanatory diagram illustrating an example of a principle for estimating a radio channel of another antenna port.
  • FIG. 1 is an explanatory diagram illustrating an example of a functional configuration of a wireless communication system.
  • FIG. 2 is an explanatory diagram illustrating an example of a configuration of a wireless communication system.
  • FIG. 3 is a sequence diagram illustrating an example of a processing procedure between apparatus
  • FIG. 8 is an explanatory diagram illustrating an example of mapping between the subframe configuration and the PRB.
  • FIG. 9 is an explanatory diagram (part 1) illustrating an example of an AP that transmits a CSI-RS defined in a subframe and a PRB.
  • FIG. 10 is an explanatory diagram showing an example of conventional mapping between a subframe configuration and a PRB.
  • FIG. 11 is an explanatory diagram showing an example of a comparison with the conventional amount of CSI-RS resources.
  • FIG. 12 is an explanatory diagram showing an example of a precoding Matrix codebook.
  • FIG. 13 is an explanatory diagram (part 2) of an example of an AP that transmits a CSI-RS defined in a subframe and a PRB.
  • FIG. 14 is an explanatory diagram illustrating an example of a second embodiment of mapping between subframe configurations and PRBs.
  • FIG. 15 is an explanatory diagram illustrating an example of switching the AP to be used.
  • FIG. 16 is an explanatory diagram (part 3) of an example of an AP that transmits a CSI-RS defined in a subframe and a PRB.
  • FIG. 17 is an explanatory diagram (part 4) of an example of an AP that transmits a CSI-RS defined in a subframe and a PRB.
  • FIG. 1 is an explanatory diagram illustrating an example of a functional configuration of a wireless communication system.
  • the wireless communication system 100 includes a base station 110 and a mobile station 120.
  • the base station 110 includes a transmission unit 111 and an antenna group 112.
  • the antenna group 112 is arranged two-dimensionally in the first direction and the second direction.
  • the first direction and the second direction are different from each other.
  • the first direction is the horizontal direction (A direction in the figure)
  • the second direction is the vertical direction (B direction in the figure).
  • the first direction and the second direction are not limited to this.
  • the first direction may be the vertical direction and the second direction may be the horizontal direction.
  • the antenna group 112 includes a plurality of antennas 113 arranged in the first direction, and a second antenna 115 disposed at a position in the second direction with respect to a part of the first antennas 114 of the plurality of antennas 113.
  • the transmission unit 111 transmits a reference signal using the plurality of antennas 113 and the second antenna 115.
  • the reference signal is a signal for the mobile station 120 to perform quality measurement, and is, for example, CSI-RS (Channel State Information-Reference Signal).
  • the transmitting unit 111 does not transmit a reference signal using the antenna 116 different from the plurality of antennas 113 and the second antenna 115 in the antenna group 112.
  • the antenna group 112 has a relatively narrow arrangement interval of the antennas in at least the second direction.
  • the antenna group 112 is an antenna group in which the arrangement interval of the antennas in the second direction is narrower than one wavelength of a radio signal transmitted from each antenna 114, 115, 116 included in the antenna group 112. For this reason, sharp directivity can be obtained in the vertical beam.
  • the antenna interval is narrow, the fading correlation increases in each radio channel connecting each antenna and the mobile station.
  • phase difference estimation is used.
  • the mobile station 120 includes a receiving unit 121 and an estimating unit 122.
  • the receiving unit 121 receives each reference signal transmitted by the plurality of antennas 113 and the second antenna 115.
  • the estimation unit 122 estimates the channel state of the antenna 116 different from the plurality of antennas 113 and the second antenna 115 in the antenna group 112 based on each reference signal received by the reception unit 121.
  • the estimation unit 122 estimates the phase difference of the channel state between the antennas arranged in the second direction in the antenna group 112 based on the reference signals transmitted by the first antenna 114 and the second antenna 115. To do.
  • the estimation unit 122 compares channel state estimation results based on the reference signals transmitted by the first antenna 114 and the second antenna 115.
  • the estimation unit 122 estimates the phase difference of the channel state between the antennas arranged in the second direction in the antenna group 112 based on the reference signals transmitted by the antennas 115a and 115b included in the second antenna 115. May be. In this case, the estimation unit 122 compares channel state estimation results based on the reference signals transmitted by the antennas 115a and 115b. The estimation unit 122 estimates the phase difference based on the result of comparing the estimation results.
  • the estimation unit 122 determines whether the antennas 116 different from the plurality of antennas 113 and the second antenna 115 Estimate channel conditions.
  • the second antenna 115 may include a plurality of antennas having different transmission signal polarizations. The content of transmitting the reference signal by using a plurality of antennas having different polarizations will be described later in the second embodiment.
  • the transmission unit 111 may transmit the reference signal using the first polarization antenna among the plurality of antennas included in the second antenna 115 in the first radio resource.
  • a radio resource is a combination of a time resource and a frequency resource.
  • the transmitter 111 uses a second polarization resource different from the first radio resource, and a reference signal is transmitted from an antenna having a second polarization different from the first polarization among a plurality of antennas included in the second antenna 115.
  • Send Details of transmitting a reference signal by a plurality of antennas having different polarizations in the first radio resource and the second radio resource will be described later in Embodiment 3.
  • FIG. 2 is an explanatory diagram illustrating an example of a configuration of a wireless communication system.
  • the radio communication system 200 includes an eNB (evolved Node B) 210 and a mobile station 220.
  • eNB evolved Node B
  • the radio communication system 100 in FIG. 1 is realized by the radio communication system 200
  • the base station 110 in FIG. 1 is realized by the eNB 210
  • the mobile station 120 in FIG. 1 is realized by the mobile station 220.
  • the eNB 210 is a multi-antenna base station and an LTE base station.
  • LTE is a communication standard of 3GPP (3rd Generation Partnership Project), which is a standardization organization.
  • the eNB 210 is wirelessly connected to the upper network and wirelessly connected to the mobile station 220.
  • the mobile station 220 is a user device such as a mobile phone or a smartphone.
  • the mobile stations 220a and 220b are located at different positions in the building 230, respectively. Note that the mobile station 220 can communicate with the eNB 210 even if it is not located in the building 230.
  • MIMO is adopted.
  • MIMO is a technique for transmitting and receiving a plurality of data streams using a plurality of antennas simultaneously.
  • the number of spatially multiplexed data streams is adaptively controlled.
  • precoding is performed in LTE MIMO transmission. Precoding is control on the transmission side in consideration of a fading state, and is to multiply a transmission signal before being transmitted from an antenna by a predetermined weight.
  • a directional beam By performing precoding, a directional beam can be formed adaptively to the mobile station, and as a result, the power of the received signal at the mobile station can be increased. For example, several patterns of precoding weights are determined in advance according to specifications.
  • the mobile station 220 measures the fading state, and selects the best precoding pattern from the measured fading state.
  • the mobile station 220 feeds back the precoding pattern to the eNB 210.
  • the feedback signal is a precoding matrix index (PMI: Precoding Matrix Indicator).
  • the wireless communication system 200 forms horizontal and vertical directional beams by a multi-antenna having a two-dimensional array arrangement, and employs, for example, 3D-MIMO or FD-MIMO (Full Dimension-MIMO).
  • 3D-MIMO or FD-MIMO (Full Dimension-MIMO)
  • FD-MIMO Full Dimension-MIMO
  • the gain of cell division can be obtained by virtual sectorization in the elevation angle direction.
  • FIG. 3 is a sequence diagram illustrating an example of a processing procedure between apparatuses performed by the wireless communication system.
  • the eNB 210 transmits the CSI-RS to the mobile station 220 (UE: User Equipment in the figure) (step S301).
  • CSI-RS is a signal for performing quality measurement.
  • the mobile station 220 calculates CSI (channel quality) (step S302), and transmits the calculated CSI to the eNB 210 (step S303).
  • the CSI transmitted from the mobile station 220 to the eNB 210 includes a channel quality indicator (CQI: Channel Quality Indicator), a precoding matrix indicator (PMI), and a rank indicator (RI: Rank Indicator).
  • CQI Channel Quality Indicator
  • PMI precoding matrix indicator
  • RI rank indicator
  • the eNB 210 performs precoding using these pieces of information (step S304).
  • the eNB 210 transmits a UE-specific RS (UE-specific Reference Signal) to the mobile station 220 (step S305).
  • the eNB 210 applies the same Precoding Matrix (precoding matrix) to the PDSCH (Physical Downlink Shared Channel) and the UE-specific RS, and transmits them to the mobile station 220.
  • the mobile station 220 performs channel estimation for calculating a channel estimation value based on the UE-specific RS (step S306).
  • the eNB 210 transmits PDSCH that is a downlink shared channel (step S307).
  • the mobile station 220 demodulates the PDSCH using the channel estimation value calculated in step S306 (step S308), and ends a series of processes.
  • FIG. 4 is a functional block diagram illustrating an example of an eNB.
  • the eNB 210 includes a CSI-RS generation unit 401, an antenna mapping unit 402, a data signal generation unit 403, a precoding processing unit 404, a physical channel multiplexing unit 405, an IFFT (Inverse Fast Fourier). (Transform) section 406, transmission RF (Radio Frequency) section 407, transmission antenna 408, reception antenna 409, reception RF section 410, FFT (Fast Fourier Transform) section 411, uplink control signal demodulation section 412, A precoding determination unit 413.
  • IFFT Inverse Fast Fourier
  • the CSI-RS generation unit 401 generates a CSI-RS and outputs it to the antenna mapping unit 402.
  • the antenna mapping unit 402 performs mapping of the CSI-RS output from the CSI-RS generation unit 401. By mapping, the CSI-RS can be transmitted from the specified transmission antenna 408 and the specified resource for each time (sub-frame) and frequency (Physical Resource Block: physical resource block).
  • the antenna mapping unit 402 outputs the mapped CSI-RS to each of a plurality (for example, 80) of physical channel multiplexing units 405.
  • the data signal generation unit 403 generates a data signal and outputs it to the precoding processing unit 404.
  • the precoding processing unit 404 performs precoding processing using the data signal output from the data signal generation unit 403 and the precoding matrix information determined by the precoding determination unit 413.
  • the precoding processing unit 404 outputs the data signal subjected to the precoding process to the physical channel multiplexing unit 405.
  • the physical channel multiplexing unit 405 multiplexes the CSI-RS output from the antenna mapping unit 402 and the data signal output from the precoding processing unit 404, and the multiplexed signal corresponds to the corresponding IFFT of the plurality of IFFT units 406.
  • the IFFT unit 406 converts the signal output from the physical channel multiplexing unit 405 into a time domain signal, and outputs the signal to the corresponding transmission RF unit 407 among the plurality of transmission RF units 407.
  • the transmission RF unit 407 generates a transmission signal by performing D / A (Digital to Analog) conversion and carrier wave modulation on the signal output from the IFFT unit 406.
  • the transmission RF unit 407 outputs the generated transmission signal to a corresponding transmission antenna 408 among a plurality (80) of transmission antennas 408 (Antenna Port: AP0 to 79).
  • the transmission antenna 408 wirelessly outputs the transmission signal output from the transmission RF unit 407 as a downlink transmission signal.
  • the reception antenna 409 receives the radio signal output from the mobile station 220 and outputs it to the reception RF unit 410.
  • the reception RF unit 410 performs carrier wave removal and A / D (Analog to Digital) conversion on the signal output from the reception antenna 409, and outputs the converted signal to the FFT unit 411.
  • the FFT unit 411 divides the signal output from the reception RF unit 410 into frequency component data by Fourier transform and outputs the data to the uplink control signal demodulation unit 412.
  • the uplink control signal demodulation unit 412 extracts the PMI from the data output from the FFT unit 411 and outputs the PMI to the precoding determination unit 413.
  • Precoding determination section 413 determines Precoding Matrix information based on the PMI output from uplink control signal demodulation section 412 and outputs the precoding matrix information to precoding processing section 404.
  • the antenna group 112 shown in FIG. 1 is realized by a plurality of transmission antennas 408.
  • FIG. 5 is a functional block diagram illustrating an example of a mobile station.
  • the mobile station 220 includes a reception antenna 501, a reception RF unit 502, an FFT unit 503, a data signal demodulation unit 504, a channel estimation unit 505, a channel estimation unit 506, and a phase difference estimation.
  • the reception antenna 501 receives the radio signal output from the eNB 210 and outputs it to the reception RF unit 502.
  • Reception RF section 502 performs carrier wave removal and A / D conversion on the signal output from reception antenna 501, and outputs the converted signal to FFT section 503.
  • FFT section 503 divides the signal output from reception RF section 502 into frequency component data by Fourier transform, and outputs the data to data signal demodulation section 504, channel estimation section 505 and channel estimation section 506.
  • the data signal demodulator 504 demodulates the PDSCH included in the signal output from the FFT unit 503 using the channel estimation value, and outputs it as user data.
  • Channel estimation section 505 calculates the channel estimation values (h0,..., H7) of AP0 to AP7 of transmission antenna 408 using the signal output from FFT section 503, and uses the calculated estimation values as phase difference estimation. Output to the unit 507.
  • the channel estimation unit 506 uses the signal output from the FFT unit 503 to calculate the channel estimation value (h8) of, for example, AP8 in the transmission antenna 408, and outputs the calculated estimation value to the phase difference estimation unit 507. To do.
  • the phase difference estimation unit 507 calculates the channel estimation value (h0,..., H79) using the estimation values calculated by the channel estimation unit 505 and the channel estimation unit 506, and supplies the calculated estimation value to the CSI calculation unit 508. Output.
  • the principle of channel estimation by the phase difference estimation unit 507 will be described later with reference to FIG.
  • CSI calculation section 508 calculates CSI (channel quality) using the estimated value calculated by phase difference estimation section 507, and outputs CSI to uplink control signal generation section 509.
  • the uplink control signal generation unit 509 generates an uplink control signal using the CSI output from the CSI calculation unit 508, and outputs the uplink control signal to the IFFT unit 510.
  • IFFT section 510 converts the signal output from uplink control signal generation section 509 into a time domain signal and outputs the signal to transmission RF section 511.
  • the transmission RF unit 511 generates a transmission signal by performing D / A conversion and carrier wave modulation on the signal output from the IFFT unit 510.
  • the transmission RF unit 511 outputs the generated transmission signal to the transmission antenna 512.
  • the transmission antenna 512 wirelessly outputs the transmission signal output from the transmission RF unit 511 as an uplink transmission signal.
  • the receiving unit 121 illustrated in FIG. 1 is realized by the receiving RF unit 502, the FFT unit 503, and the like. Moreover, the estimation part 122 shown in FIG. 1 is implement
  • FIG. 6 is an explanatory diagram illustrating an example of a transmission antenna of the eNB.
  • a plurality (80) of transmission antennas 408 have 80 antenna ports AP0 to AP79 for each antenna.
  • the horizontal direction indicates the horizontal direction
  • the vertical direction indicates the vertical direction.
  • AP0 to AP7 are arranged at equal intervals in the horizontal direction.
  • AP0, AP8,..., AP64, AP72 are arranged at equal intervals in the vertical direction.
  • the other antennas are similarly arranged at equal intervals in each direction.
  • one line in an oblique direction indicates one antenna (antenna port), and antenna ports that intersect each other indicate that the polarization is different.
  • antenna ports that intersect each other indicate that the polarization is different.
  • AP0 and AP4 have different polarizations.
  • the vertical beam can obtain a sharp directivity.
  • fading correlation increases in the radio channel of each antenna in the vertical direction, and the phase difference of each radio channel depends on the arrival direction of the signal.
  • the radio channels of other antenna ports not transmitting CSI-RS can also be estimated. For example, if the phase difference between the radio channels of AP0 and AP8 adjacent to AP0 in the vertical direction can be estimated, the radio channel states of other APs arranged in different columns in the vertical direction from AP0 are also estimated. be able to. In the first embodiment, such phase difference estimation is used.
  • FIG. 7 is an explanatory diagram illustrating an example of a principle for estimating a radio channel of another antenna port.
  • AP0, AP8, AP16,..., AP (8 ⁇ n) are arranged in the vertical direction.
  • a CSI-RS is transmitted from AP0 and AP8, and the radio channel of another AP (8 ⁇ n) can be estimated based on the phase difference ⁇ h v of the radio channel. Specifically, it can be expressed by the following formulas (1) and (2).
  • n 0,...
  • h 8 h 0 ⁇ ⁇ h v (1)
  • h is the phase
  • d is the distance between the antenna ports in the vertical direction
  • ⁇ is the angle with respect to the mobile station 220
  • ⁇ is the wavelength of the signal.
  • the phase of the mobile station 220 has received from AP0 CSI-RS
  • the difference between the phase of the mobile station 220 has received from AP8 CSI-RS is a phase difference Delta] h v.
  • FIG. 8 is an explanatory diagram illustrating an example of mapping between the subframe configuration and the PRB.
  • OFDMA Orthogonal Frequency Multiple Access
  • 12 subcarriers (180 kHz) adjacent at 15 kHz intervals in the frequency direction are separated as one PRB.
  • radio resources divided every 1 ms in the time direction can be allocated to users.
  • Physical channels and signals are mapped to the PRB.
  • Physical channels include PDSCH, PCFICH (Physical Control Format Channel), PHICH (Physical HARQ Indicator Channel), and PDCCH (Physical Downlink Control).
  • PCFICH is a channel for notifying how many symbols at the head of each subframe are reserved as an area where downlink control information can be transmitted.
  • PHICH is a channel for transmitting delivery confirmation information (ACK / NACK) for PUSCH (Physical Uplink Shared Channel).
  • PUSCH is a shared data channel for transmitting uplink user data.
  • the PDCCH is used to notify radio resource allocation information to a user selected by the eNB 210 through scheduling.
  • mapping 800 signals such as Cell-specific Cell-specific RS, user-specific UE-specific RS, and CSI-RS are assigned.
  • Cell index is defined in the range of A to D
  • CDM (Code Division Multiple) group is defined in the range of x, y, z, u, v.
  • Ax of CSI-RS is used for AP0 and AP1 (see FIG. 6) among AP0 to AP7 arranged in a specific horizontal column.
  • CSI-RS Ay is used.
  • CSI-RS Az is used.
  • CSI-RS Au is used.
  • Av is used for AP8 that is different from AP0 in the vertical direction.
  • x, y, z, u, and v are applied according to the AP.
  • the eNB 210 notifies the mobile station 220 of CSI-RS Configuration using an upper layer (for example, PDCCH or PDSCH). Thereby, the mobile station can specify the mapping position (corresponding to Cell index) of CSI-RS.
  • FIG. 9 is an explanatory diagram (part 1) illustrating an example of an AP that transmits a CSI-RS defined in a subframe and a PRB.
  • An explanatory diagram 900 shows an AP that transmits CSI-RS defined in a subframe and a PRB.
  • AP0 to 7, 8 are defined in subframe 0 and PRB0.
  • AP0 to AP7 and AP8 are also defined in other subframes and PRBs.
  • FIG. 10 is an explanatory diagram showing an example of conventional mapping between a subframe configuration and a PRB.
  • a mapping 1000 shown in FIG. 10 shows a case where eight antennas (AP0 to AP7) are used.
  • the cell index is defined by five cells A to E, for example.
  • E is arranged in the Cell index.
  • the mapping 800 in FIG. 8 does not use the E cell as compared with the mapping 1000, and assigns the CSI-RS Av for AP8 thereto. Therefore, in the mapping 800 of FIG. 8, even when the number of antennas is 80, the number of CSI-RS used resources is not equal to the number of antennas, so the amount of CSI-RS used resources can be suppressed. .
  • FIG. 11 is an explanatory diagram showing an example of a comparison with the conventional amount of CSI-RS resources.
  • the number of antennas horizontal ⁇ vertical
  • the number of resources (16) corresponding to the number of antennas is necessary in the prior art. It is.
  • the number of antennas when the number of antennas (horizontal ⁇ vertical) is 80 of 8 ⁇ 10, conventionally, the number of resources (80) corresponding to the number of antennas is required.
  • ⁇ h v can be expressed as the following equation (6).
  • ⁇ h v can be calculated even when a distant antenna is used.
  • the phase difference of the radio channel can be obtained even when using a distant antenna within a range satisfying the conditional expression (7).
  • the antenna interval d 0.5 ⁇
  • antenna spacing d 0.3 ⁇
  • the mobile station 220 selects an optimum value of Precoding Matrix from a code book used for precoding.
  • the mobile station 220 has a Precoding Matrix candidate (codebook).
  • Precoding Matrix is defined in the specification, for example.
  • an example of a precoding matrix codebook will be described below.
  • FIG. 12 is an explanatory diagram illustrating an example of a precoding matrix codebook.
  • 12A shows a codebook 1210 for horizontal component precoding.
  • PMI H indicating types and coefficients W H0 to H7 corresponding to the types are associated.
  • H is a channel estimation value
  • W is a weighting coefficient of Precoding Matrix.
  • the code book 1210 indicates that there are 16 types of horizontal component precoding candidates.
  • FIG. 12B shows a codebook 1220 for vertical component precoding.
  • PMI V indicating the type and W V0 to V9 corresponding to each type are associated.
  • the code book 1220 indicates that there are eight types of vertical component precoding candidates.
  • the mobile station 220 uses the code book 1210 to select an optimal precoding candidate. Specifically, the mobile station 220 estimates the channel capacity in the case where each horizontal component precoding candidate is applied to the antenna in one column in the horizontal direction using the following equation (8), and this is the maximum. Select a candidate.
  • the mobile station 220 can calculate the weighting factors W 0 to 7 corresponding to the APs 0 to 7 arranged in a line in the horizontal direction. Further, the mobile station 220 can calculate the weighting factors W 0,8, ... , 72 corresponding to the APs 0, 8 ,.
  • the mobile station 220 transmits the PMI of the horizontal direction component and the vertical direction component corresponding to the calculated optimum value to the eNB 210.
  • the eNB 210 applies a weighting factor W based on the PMI report from the mobile station 220 and transmits a data signal as shown in the following equation (10).
  • the propagation path of the antenna without CSI-RS transmission is estimated. For this reason, an increase in radio resources used for CSI-RS transmission can be suppressed. Specifically, even if the number of antennas increases in the vertical direction in 3D-MIMO, the number of CSI-RS used resources is not the same as the number of antennas. Can do.
  • Embodiment 2 ten antenna ports AP0 to 7, 8, and 12 shown in FIG. 6 are used.
  • the APs 8 and 12 have different polarizations.
  • the phase difference between AP0 and AP8 and the phase difference between AP4 and AP12 are the same.
  • APs 8 and 12 have fading fluctuations independent of each other. That is, in each fading fluctuation of AP8, 12, even if one level is low, the other level is not necessarily low.
  • FIG. 13 is an explanatory diagram (part 2) of an example of an AP that transmits a CSI-RS defined in a subframe and a PRB.
  • the explanatory diagram 1300 shows an AP that transmits a CSI-RS defined in a subframe and a PRB.
  • AP0 to 7, 8, and 12 are defined in subframe 0 and PRB0.
  • AP0 to 7, 8, and 12 are also defined in other subframes other than subframes 0 and PRB0 and other PRBs.
  • FIG. 14 is an explanatory diagram illustrating an example of a second embodiment of mapping between subframe configurations and PRBs.
  • mapping 1400 shown in FIG. 14 Av, Bv, Cv, and Dv are mapped to reference numerals 1401 and 1402 for AP8 and AP12 that are different from AP0 in the vertical direction.
  • mapping 1400 in FIG. 14 makes the E cell unusable as compared with the mapping 1000, and the CSI-RS Av, Bv, Cv, and Dv for the AP8 and AP12 are mapped there. Therefore, in mapping 1400, even when the number of antennas is 80, the number of CSI-RS used resources is not the same as the number of antennas, so that the amount of CSI-RS used resources can be suppressed.
  • the same effect as in the first embodiment can be obtained.
  • the average of ⁇ h v is calculated for each of AP8 and AP12 having independent fading fluctuations. For this reason, even when the reception level is low due to fading fluctuation of one AP, the reception level of the other AP can be considered. Therefore, it is possible to suppress a decrease in estimation accuracy of the phase difference, and it is possible to improve the accuracy of channel estimation.
  • Embodiment 3 Next, Embodiment 3 will be described.
  • a case will be described in which channel estimation is performed by alternately using APs 8 and 12 that are arranged at different positions in the vertical direction from AP0 and have mutually different polarizations.
  • parts different from the first and second embodiments will be described.
  • FIG. 15 is an explanatory diagram illustrating an example of switching the AP to be used.
  • FIG. 15A shows a case where AP8 is used.
  • (b) has shown the case where AP12 is used.
  • (A) and (b) show that CSI-RSs are alternately transmitted in the time direction or frequency direction from APs 8 and 12 having different polarizations.
  • FIG. 16 is an explanatory diagram (part 3) of an example of an AP that transmits a CSI-RS defined in a subframe and a PRB.
  • the explanatory diagram 1600 shows an AP that transmits CSI-RS defined in a subframe and a PRB. As shown in the explanatory diagram 1600, the AP that transmits the CSI-RS differs according to the subframe number and the PRB number.
  • AP0 to 7, 8 are defined in subframe 0 and PRB0.
  • APs 0 to 7 and 12 are defined.
  • APs 0 to 7 and 12 are defined.
  • AP0 to AP7 and AP8 are defined in subframe 1 and PRB1. In this way, the CSI-RSs are alternately transmitted from the APs 8 and 12 in the time direction or the frequency direction.
  • the mapping between the subframe configuration and the PRB is the same as the mapping 800 (see FIG. 8) of the first embodiment. Therefore, the number of resources by CSI-RS can be reduced as compared with mapping 1400 of Embodiment 2 (see FIG. 14).
  • the same effect as in the first embodiment can be obtained.
  • the average of ⁇ h v is calculated for each of AP8 and AP12 with independent fading fluctuations. For this reason, even when the reception level is low due to fading fluctuation of one AP, the reception level of the other AP can be considered. Further, since CSI-RS is transmitted using different radio resources, it is possible to suppress a decrease in estimation accuracy of the phase difference while suppressing an increase in radio resources, and it is possible to improve the accuracy of channel estimation.
  • FIG. 17 is an explanatory diagram (part 4) of an example of an AP that transmits a CSI-RS defined in a subframe and a PRB.
  • Description FIG. 1700 shows an AP that transmits CSI-RS defined in subframes and PRBs.
  • APs to which CSI-RSs are transmitted alternately use sets APs having different polarizations (for example, AP8 and AP12) depending on whether the subframe number is even or odd.
  • APs to which CSI-RS is transmitted have APs with different polarizations (for example, AP9 and AP13) shifted in the parallel direction according to the PRB number (for example, AP10 and AP14).
  • AP0 to 7, 8 are defined in subframe 0 and PRB0.
  • APs 0 to 7 and 12 are defined.
  • AP0 to AP7 and AP13 are defined in subframe 0 and PRB1.
  • APs 0 to 7 and 9 are defined.
  • CSI-RS is transmitted from different APs in the time direction or the frequency direction.
  • the same effect as that of the third embodiment can be obtained, and channel estimation can be performed using a plurality of different APs evenly. Therefore, the accuracy of channel estimation can be improved by the diversity effect. Can be improved.

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

Abstract

L'invention concerne une station de base (110) qui est pourvue d'un groupe d'antennes (112) agencé en deux dimensions dans la direction horizontale et la direction verticale. La station de base (110) émet des signaux de référence à l'aide d'une pluralité d'antennes (113) alignées dans la direction horizontale et de secondes antennes (115) agencées dans la direction verticale, dans la position d'une première antenne (114) qui est l'une de la pluralité d'antennes (113). Une station mobile (120) estime, sur la base de chacun des signaux de référence émis par la pluralité d'antennes (113) et les secondes antennes (115), les états de canal d'antennes (116) dans le groupe d'antennes (112) qui sont différentes de la pluralité d'antennes (113) et des secondes antennes (115).
PCT/JP2014/070792 2014-08-06 2014-08-06 Système de communication sans fil, station de base, station mobile, procédé d'émission et procédé d'estimation WO2016021013A1 (fr)

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US20130308715A1 (en) * 2012-05-18 2013-11-21 Samsung Electronics Co., Ltd Apparatus and method for channel state information codeword construction for a cellular wireless communication system
WO2014038347A1 (fr) * 2012-09-07 2014-03-13 株式会社エヌ・ティ・ティ・ドコモ Station de base sans fil, système de communication sans fil et procédé de communication sans fil
WO2014038321A1 (fr) * 2012-09-07 2014-03-13 株式会社エヌ・ティ・ティ・ドコモ Procédé de communication radio, terminal d'utilisateur, station de base radio, et système de communication radio
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US20130258964A1 (en) * 2012-03-30 2013-10-03 Samsung Electronics Co., Ltd. Apparatus and method for channel-state-information pilot design for an advanced wireless network
US20130308715A1 (en) * 2012-05-18 2013-11-21 Samsung Electronics Co., Ltd Apparatus and method for channel state information codeword construction for a cellular wireless communication system
WO2014038347A1 (fr) * 2012-09-07 2014-03-13 株式会社エヌ・ティ・ティ・ドコモ Station de base sans fil, système de communication sans fil et procédé de communication sans fil
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