WO2014103978A1 - Dispositif de station de base sans fil, système de communication sans fil, et procédé de communication sans fil - Google Patents

Dispositif de station de base sans fil, système de communication sans fil, et procédé de communication sans fil Download PDF

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Publication number
WO2014103978A1
WO2014103978A1 PCT/JP2013/084407 JP2013084407W WO2014103978A1 WO 2014103978 A1 WO2014103978 A1 WO 2014103978A1 JP 2013084407 W JP2013084407 W JP 2013084407W WO 2014103978 A1 WO2014103978 A1 WO 2014103978A1
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base station
transmission
user terminal
radio base
variation
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PCT/JP2013/084407
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English (en)
Japanese (ja)
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アナス ベンジャブール
祥久 岸山
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株式会社Ｎｔｔドコモ
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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W72/00—Local resource management
    • H04W72/50—Allocation or scheduling criteria for wireless resources
    • H04W72/54—Allocation or scheduling criteria for wireless resources based on quality criteria

Definitions

  • the present invention relates to a radio base station apparatus, a radio communication system, and a radio communication method applicable to a cellular system or the like.
  • HSDPA High Speed Packet Access Access
  • HSUPA High SpeckWed SpeckWed
  • CDMA Wideband-Code Division Multiple Access
  • the third generation system can achieve a maximum transmission rate of about 2 Mbps on the downlink using generally a fixed bandwidth of 5 MHz.
  • a maximum transmission rate of about 300 Mbps on the downlink and about 75 Mbps on the uplink can be realized using a variable band of 1.4 MHz to 20 MHz.
  • LTE-A LTE Advanced
  • inter-cell orthogonalization is one promising technique for further improving the system performance over the LTE system.
  • orthogonalization within a cell is realized by orthogonal multi-access for both uplink and downlink. That is, in the downlink, orthogonalization is performed between user terminals UE (User Equipment) in the frequency domain.
  • UE User Equipment
  • W-CDMA Wideband Code Division Multiple Access
  • a coordinated multi-point transmission / reception (CoMP: Coordinated Multi-Point transmission / reception) technique is being studied as a technique for realizing orthogonalization between cells.
  • CoMP transmission / reception a plurality of cells perform transmission / reception signal processing in cooperation with one or a plurality of user terminals UE.
  • simultaneous transmission of multiple cells to which precoding is applied, cooperative scheduling / beamforming, and the like are being studied.
  • the application of these CoMP technologies is expected to improve the throughput characteristics of the user terminal UE located particularly at the cell edge.
  • the radio resources are not effectively used, and the throughput characteristic of the entire system and the throughput characteristic of the user terminal UE at the cell edge deteriorate. Can occur. That is, in order to improve the throughput characteristics by applying the CoMP technique, it is required to appropriately allocate radio resources to the user terminal UE at the cell edge.
  • the present invention has been made in view of such points, and provides a radio base station apparatus, a radio communication system, and a radio communication method capable of improving the throughput characteristics of the entire system and the cell terminal user terminal UE when performing CoMP transmission.
  • the purpose is to provide.
  • a radio base station apparatus is a radio base station apparatus in a radio communication system comprising a plurality of radio base station apparatuses and a user terminal configured to be capable of cooperative multipoint transmission / reception with the plurality of radio base station apparatuses.
  • the radio base station apparatus calculates a variation degree of feedback information between transmission points of cooperative multipoint transmission fed back from the user terminal, and according to the variation degree calculated by the calculation unit. And determining a radio resource to be allocated to the user terminal.
  • a radio communication system of the present invention is a radio communication system comprising a plurality of radio base station devices and a user terminal configured to be capable of cooperative multipoint transmission / reception with the plurality of radio base station devices, wherein the user terminal Has a transmission unit that transmits feedback information for each transmission point of cooperative multipoint transmission, and the radio base station apparatus varies feedback information between transmission points of cooperative multipoint transmission fed back from the user terminal. It has a calculation part which calculates a degree, and a determination part which determines the radio resource allocated to the user terminal according to the variation degree calculated by the calculation part.
  • a radio communication method of the present invention is a radio communication method of a radio communication system comprising a plurality of radio base station devices and a user terminal configured to be capable of cooperative multipoint transmission / reception with the plurality of radio base station devices.
  • the method includes a step of calculating a degree of variation and a step of determining a radio resource to be allocated to the user terminal according to the calculated degree of variation.
  • the present invention it is possible to improve the throughput characteristics of the entire system and the cell terminal user terminal UE when performing CoMP transmission.
  • FIG. 10 is a flowchart for explaining an operation of correcting a scheduling metric according to the degree of CQI variation between transmission points in a radio base station apparatus. It is a figure for demonstrating the system configuration
  • Coordinated Scheduling / Coordinated Beamforming is a method of transmitting a shared data channel from one cell only to one user terminal UE, and considers interference from other cells and interference to other cells as shown in FIG. 1A. Then, radio resources are allocated in the frequency / space region.
  • joint processing is a method of transmitting a shared data channel from a plurality of cells simultaneously by applying precoding. As shown in FIG. 1B, a shared data channel is transmitted from a plurality of cells to one user terminal UE. As shown in FIG. 1C, there is a joint transmission to be transmitted and a dynamic point selection (DPS) for instantaneously selecting one cell and transmitting a shared data channel.
  • DPS dynamic point selection
  • a plurality of remote radio devices (RRE: Remote Radio Equipment) connected to a radio base station device (radio base station device eNB) by an optical fiber or the like. ) (Centralized control based on the RRE configuration) and a configuration of the radio base station device (radio base station device eNB) (autonomous distributed control based on the independent base station configuration), as shown in FIG. 2B.
  • RRE Remote Radio Equipment
  • FIG. 2A shows a configuration including a plurality of remote radio apparatuses RRE, it may be configured to include only a single remote radio apparatus RRE as shown in FIG.
  • the remote radio apparatuses RRE1 and RRE2 are centrally controlled by the radio base station apparatus eNB.
  • an optical fiber is used between a radio base station apparatus eNB (concentrated base station) that performs baseband signal processing and control of a plurality of remote radio apparatuses RRE and each cell (that is, each remote radio apparatus RRE). Since connection is performed using a baseband signal, radio resource control between cells can be performed collectively in a centralized base station. That is, the problem of signaling delay and overhead between radio base station apparatuses eNB, which is a problem in the independent base station configuration, is small, and high-speed radio resource control between cells is relatively easy. Therefore, in the RRE configuration, a method using high-speed signal processing between cells such as simultaneous transmission of a plurality of cells can be applied in the downlink.
  • radio resource allocation control such as scheduling is performed in each of the plurality of radio base station apparatuses eNB (or RRE).
  • the radio resource allocation information such as timing information and scheduling is transmitted to any one of the radio base stations as necessary in the X2 interface between the radio base station apparatus eNB of the cell 1 and the radio base station apparatus eNB of the cell 2. It transmits to apparatus eNB and performs cooperation between cells.
  • FIG. 3 is a schematic diagram for explaining a cell configuration of the radio communication system.
  • FIG. 4 is a sequence diagram for explaining an operation of determining a CoMP transmission transmission cell.
  • the radio base station apparatus eNB in the serving cell notifies the user terminal UE of a measurement candidate cell (RRM measurement set) 110 by a control signal of an RRC (Radio Resource Control) protocol. (Step S11).
  • RRM measurement set a measurement candidate cell
  • RRC Radio Resource Control
  • the user terminal UE Based on CRS (Cell Specific Reference Signal) or CSI-RS (Channel State Information Reference Signal) received from each measurement candidate cell 110, the user terminal UE receives an RSRP (Reference Signal Received Receive Rigid RS). Measure. And the user terminal UE determines whether CoMP transmission should be requested
  • RSRP Reference Signal Received Receive Rigid RS
  • the determination as to whether CoMP transmission should be requested is performed based on, for example, whether the RSRP / RSRQ of the neighboring cell exceeds the RSRP / RSRQ of the serving cell, or whether the RSRP / RSRQ of the serving cell falls below a threshold value.
  • a measurement report (measurement report) result is reported to the radio base station apparatus eNB by higher layer signaling (for example, RRC signaling), and CoMP transmission is performed. Is requested (step S12).
  • the measurement report result transmitted from the user terminal UE to the radio base station apparatus eNB includes RSRP / RSRQ of the serving cell and RSRP / RSRQ of neighboring cells.
  • the radio base station apparatus eNB specifies a channel quality measurement cell (CoMP measurement set) 111 from the measurement candidate cells 110 based on the measurement report result. Then, the radio base station apparatus eNB transmits a connection reconfiguration signal (RRC Connection Reconfiguration) including notification of the channel quality measurement cell (CoMP measurement set) 111 to the user terminal UE to which CoMP transmission is to be applied ( Step S13).
  • RRC Connection Reconfiguration a connection reconfiguration signal
  • connection reconfiguration completion signal RRC Connection Reconfiguration Complete
  • the user terminal UE In response to the connection reconfiguration signal from the radio base station apparatus eNB, the user terminal UE sends a connection reconfiguration completion signal (RRC Connection Reconfiguration Complete) for notifying that the notification of the channel quality measurement cell 111 has been received. It transmits with respect to the wireless base station apparatus eNB (step S14).
  • the user terminal UE measures CSI (Channel State Information) of the channel quality measurement cell 111 notified from the radio base station apparatus eNB. Then, the user terminal UE feeds back the CSI measured for each channel quality measurement cell 111 to the radio base station apparatus eNB by PUCCH (Physical Uplink Control Channel) (step S15).
  • CSI Channel State Information
  • PUCCH Physical Uplink Control Channel
  • the CSI fed back from the user terminal UE includes a rank number (RI: Rank Indicator) and a precoder (PMI: Precoding Matrix Indicator) known in the codebook between the radio base station apparatus eNB and the user terminal UE, and
  • CQI Channel Quality Indicator
  • RI Rank Indicator
  • PMI Precoding Matrix Indicator
  • CQI Channel Quality Indicator
  • the radio base station apparatus eNB determines a CoMP transmission transmission point (CoMP transmission points) 112 from the channel quality measurement cells 111 based on a plurality of CSIs fed back from the user terminal UE.
  • the radio base station apparatus eNB performs CoMP transmission by appropriately selecting Coordinated Scheduling / Coordinated Beamforming and Joint processing shown in FIG. 1 for the CoMP transmission transmission cell thus determined.
  • the plurality of CQIs or RSRQ / RSRPs fed back to the radio base station apparatus eNB include the user terminal UE located in the vicinity of the cell center and the user terminal UE located in the cell edge (hereinafter referred to as “ The degree of variation between cells (transmission points) differs from the cell edge UE).
  • the degree of variation between cells (transmission points) differs from the cell edge UE.
  • a plurality of CQIs are fed back will be described here, a plurality of other measurement results (RSRQ / RSRQ, etc.) may be used.
  • the user terminal UE located in the vicinity of the cell center has a large difference between the CQI of the cell where the user terminal UE is located and the CQI of neighboring cells.
  • the degree of CQI variation between cells is relatively large.
  • the cell edge UE has a small difference between the CQI of the cell in which the cell edge UE is located and the CQI of neighboring cells, and the degree of CQI variation between cells is relatively small.
  • the received power of the signal from the radio base station apparatus eNB of each cell is small. For this reason, in CQI fed back from the cell edge UE, a channel estimation error becomes relatively large.
  • radio resources are excessively allocated to the cell edge UE having a relatively large channel estimation error in this way, the radio resources are not effectively used, and as a result, the throughput characteristics of the entire system and the cell edge UE are deteriorated. Things can happen.
  • the present inventors pay attention to this point and identify the cell edge UE from the degree of variation in feedback information (CQI) between transmission points fed back from the user terminal UE, and excessive radio resources are allocated to the identified cell edge UE. It was found that avoiding the situation can improve the throughput characteristics of the entire system and the cell edge UE, and the present invention has been completed.
  • CQI feedback information
  • the radio base station apparatus eNB calculates the degree of variation in feedback information between transmission points fed back from the user terminal UE, and assigns radio resources to be allocated to the user terminal UE according to the calculated degree of variation. It is to decide. More specifically, the radio resource amount allocated to the user terminal UE having a small variation degree of feedback information between transmission points fed back from the user terminal UE is relatively reduced while the radio resource allocated to the user terminal UE having a large variation degree is used. Increase the amount of resources relatively.
  • the degree of variation in feedback information between transmission points fed back from the user terminal UE is calculated, and radio resources to be allocated to the user terminal UE are determined according to the calculated degree of variation.
  • radio resources to be allocated to user terminals can be determined according to the degree of variation in feedback information between transmission points where it can be determined whether or not the user terminal UE is a cell edge UE. Therefore, radio resources are excessively allocated to the cell edge UE. Therefore, it is possible to improve the throughput characteristics of the entire system and the user terminal UE at the cell edge.
  • the amount of radio resources allocated to the user terminal UE with a small degree of variation in feedback information between transmission points fed back from the user terminal UE is relatively reduced, while being allocated to the user terminal UE with a large degree of variation. Increase the amount of radio resources relatively.
  • it is possible to effectively avoid a situation where radio resources are excessively allocated to the cell edge UE it is possible to improve the throughput characteristics of the entire system and the user terminal UE at the cell edge.
  • the radio base station apparatus eNB determines (adjusts) radio resources to be allocated to the cell edge UE by correcting a scheduling metric that determines radio resource allocation according to the degree of variation in feedback information between transmission points. To do.
  • a scheduling metric that determines radio resource allocation according to the degree of variation in feedback information between transmission points.
  • radio resources to be allocated to the user terminal UE are determined, so that certain accuracy is ensured according to the degree of variation in feedback information between transmission points fed back from the user terminal UE.
  • a proportional fairness (PF) scheduling metric that ensures fairness for the user terminal UE, a scheduling metric that maximizes the instantaneous data rate in the user terminal UE, and the like can be considered.
  • PF proportional fairness
  • the scheduling metric to be corrected is not limited to this and can be changed as appropriate.
  • the PF scheduling metric the evaluation value represented by the ratio of channel information for each radio resource (that is, channel information / average channel information) to the average value of channel information for each radio resource (average channel information) is large. Radio resources are preferentially allocated to the user terminal UE.
  • a Weighted PF (WPF) scheduling metric that adjusts radio resources allocated to the user terminal UE has been proposed in terms of both fairness and data rate. This WPF scheduling metric can also be included in the scheduling metric to be corrected in the present invention. In the following, a case where these PF scheduling metric and WPF scheduling metric are corrected by the wireless communication method according to the present invention will be described.
  • the radio resource of user i at time n is proportional to WP i [n] and is obtained by the following (Equation 2).
  • WP i [n] (R inst [n]) ⁇ / (R avg [n]) ⁇
  • ⁇ and ⁇ are weighting coefficients for adjusting radio resources allocated to the user terminal UE from the viewpoint of improving fairness and data rate.
  • ⁇ / ⁇ is increased, the scheduling operation aims to maximize the sum of the data rates.
  • the radio base station apparatus eNB calculates the degree of variation in feedback information between transmission points fed back from the user terminal UE in the process of determining the CoMP transmission transmission cell described above. Then, the PF scheduling metric and the WPF scheduling metric described above are corrected according to the calculated degree of variation. For example, the PF scheduling metric and the WPF scheduling metric described above are set in accordance with the degree of CQI variation between the radio base station apparatuses eNB of the channel quality measurement cell 111 (the cell specified by the CoMP measurement set) fed back from the user terminal UE. to correct.
  • the radio base station apparatus eNB that is a calculation target of the degree of variation is not limited to the channel quality measurement cell 111.
  • the radio base station apparatus eNB uses the radio base station apparatus eNB of the CoMP transmission transfer cell 112 (cell designated as CoMP transmission points) or the measurement candidate cell 110 (cell specified by the RRM measurement set) as a calculation target of the variation degree. ) Can be selected.
  • the radio base station apparatus eNB corrects the existing PF scheduling metric and WPF scheduling metric described above as follows. That is, the radio resource P i [n] when the PF scheduling metric is applied and the radio resource when the WPF scheduling metric is applied are proportional to WP i [n]. It is calculated
  • “F” indicates a parameter for adjusting a radio resource allocation opportunity according to the degree of variation in feedback information (CQI) between transmission points.
  • “ ⁇ ” represents a weighting coefficient for further adjusting the parameter F.
  • “F ⁇ ” constitutes a parameter for adjusting the radio resource allocation opportunity.
  • the parameter F can be obtained by, for example, (Formula 5).
  • X i indicates a report value measured for the i-th transmission point by a user terminal UE with respect to the radio base station apparatus eNB.
  • X i includes, for example, CQI, RSRP, an average data rate of transmission data transmitted from the i-th transmission point, and the like.
  • N indicates the total number of transmission points.
  • the denominator of the fraction constituting the right side of (Equation 5) indicates the calculated average of X i
  • the numerator indicates the geometric average of X i .
  • the parameter F can be calculated
  • the value of the parameter F is changed to the degree of variation in feedback information between transmission points fed back from the user terminal UE. It can be varied accordingly. That is, when the degree of variation in feedback information between transmission points fed back from the user terminal UE is relatively large, the value of the parameter F is set to be relatively large. On the other hand, when the degree of variation in feedback information between transmission points fed back from the user terminal UE is relatively small, the value of the parameter F is set to be relatively small.
  • FIG. 5 is a flowchart for explaining an operation of correcting the scheduling metric according to the degree of CQI variation between transmission points fed back from the user terminal UE in the radio base station apparatus eNB according to the present invention.
  • FIG. 5 shows from the step of transmitting CSI-RS from the radio base station apparatus eNB to the step of transmitting user data (shared channel data) based on the scheduling result.
  • a part of processing in the user terminal UE is shown for convenience of explanation.
  • the radio base station apparatus eNB measures the channel information of these channel quality measurement cells 111.
  • the radio base station apparatus eNB measures the channel information of these channel quality measurement cells 111.
  • the user terminal UE measures the CQI of each transmission point based on the CSI-RS (step S22).
  • the measured CQI is fed back to the radio base station apparatus eNB (step S23). In this case, the CQIs of all channel quality measurement cells 111 are measured and fed back.
  • the radio base station apparatus eNB calculates the degree of CQI variation between the plurality of channel quality measurement cells 111 (transmission points) fed back from the user terminal UE (step S24). Then, the radio base station apparatus eNB corrects the scheduling metric according to the calculated degree of variation (Step S25). For example, when the predetermined scheduling metric is a PF scheduling metric (Equation 1) or a WPF scheduling metric (Equation 2), the radio base station apparatus eNB incorporates the parameter F described above into the calculation formula, thereby The scheduling metric is corrected (Equation 3 and Equation 4).
  • the scheduling metric reduces the amount of radio resources allocated to the user terminal UE having a small degree of variation in CQI between transmission points from the user terminal UE, while increasing the amount of radio resources allocated to the user terminal UE having a large degree of variation.
  • the scheduling metric to be corrected Note that a scheduling metric equivalent to an existing scheduling metric is applied to the user terminal UE to which CoMP transmission is not applied.
  • the radio base station apparatus eNB determines the user terminal UE to be scheduled based on the corrected scheduling metric (step S26). In this case, the radio resource allocated to the user terminal UE with a small degree of CQI variation between the transmission points is set to be small, and the radio resource allocated to the user terminal UE with a large degree of CQI variation between the transmission points is large. Is set. And the radio base station apparatus eNB transmits user data (shared channel data) with respect to the user terminal UE determined in this way (step S27).
  • the degree of CQI variation between the plurality of channel quality measurement cells 111 (transmission points) fed back from the user terminal UE is calculated, and the radio resource allocated to the cell edge UE according to the calculated degree of variation. To decide. As a result, it is possible to avoid a situation in which radio resources are excessively allocated to the cell edge UE when performing CoMP transmission from the radio base station apparatus eNB, and thus it becomes possible to improve the throughput characteristics of the entire system and the user terminal UE at the cell edge. .
  • the scheduling metric is corrected using the parameter F according to the degree of variation between transmission points fed back from the user terminal UE.
  • the channel estimation error in the cell edge UE generally increases as the number of transmission points increases. For this reason, it is preferable as an embodiment to reflect the influence of the number of transmission points on the parameter used for correcting the scheduling metric.
  • the degree of variation becomes small and the parameter F is normalized by the number of transmission points.
  • the opportunity to allocate radio resources to the corresponding user terminal UE can be reduced as in the case where the parameter F is small.
  • the radio base station apparatus eNB corrects the above-described existing PF scheduling metric (Equation 1) and WPF scheduling metric (Equation 2) as follows. That is, the radio resource P i [n] when the PF scheduling metric is applied is obtained by the following (Expression 10) and (Expression 11).
  • P i [n] (F / N) ⁇ ⁇ R inst [n] / R avg [n]
  • P i [n] F ⁇ / N ⁇ ⁇ R inst [n] / R avg [n]
  • N indicates the total number of transmission points.
  • Equation 10 represents a calculation formula when weighting is performed with a coefficient common to the parameter F and the number N of transmission points, and (Equation 11) is weighted with a different coefficient to the parameter F and the number N of transmission points. The calculation formula is shown.
  • the radio resource WP i [n] when the WPF scheduling metric is applied is obtained by the following (Expression 12) and (Expression 13).
  • WP i [n] (F / N) ⁇ ⁇ (R inst [n]) ⁇ / (R avg [n]) ⁇
  • WP i [n] F ⁇ / N ⁇ ⁇ (R inst [n]) ⁇ / (R avg [n]) ⁇
  • (Equation 12) shows a calculation formula when weighting is performed with a coefficient common to the parameter F and the transmission point number N
  • (Equation 13) is weighted with a different coefficient to the parameter F and the transmission point number N.
  • the calculation formula when performing is shown. In these calculation formulas, when the parameter F is normalized by the number N of transmission points, “(F / N) ⁇ ” and “F ⁇ / N ⁇ ” constitute parameters for adjusting the
  • FIG. 6 is an explanatory diagram of a system configuration of the wireless communication system according to the present embodiment.
  • the radio communication system shown in FIG. 6 is a system including, for example, an LTE system or SUPER 3G.
  • carrier aggregation in which a plurality of fundamental frequency blocks with the system band of the LTE system as a unit is integrated is used.
  • this wireless communication system may be called IMT-Advanced or 4G.
  • the radio communication system 1 includes radio base station apparatuses 20A and 20B and a plurality of first and second user terminals 10A and 10B communicating with the radio base station apparatuses 20A and 20B. It consists of The radio base station apparatuses 20 ⁇ / b> A and 20 ⁇ / b> B are connected to the higher station apparatus 30, and the higher station apparatus 30 is connected to the core network 40.
  • the radio base station apparatuses 20A and 20B are connected to each other by wired connection or wireless connection.
  • the first and second user terminals 10A and 10B can communicate with the radio base station apparatuses 20A and 20B in the cells 1 and 2.
  • the upper station device 30 includes, for example, an access gateway device, a radio network controller (RNC), a mobility management entity (MME), and the like, but is not limited thereto.
  • RNC radio network controller
  • MME mobility management entity
  • the first and second user terminals 10A and 10B include an LTE terminal and an LTE-A terminal.
  • the description will proceed as the first and second user terminals 10A and 10B unless otherwise specified.
  • the radio base station apparatuses 20A and 20B and the first and second user terminals 10A and 10B which are mobile terminal apparatuses, are described as wirelessly communicating, but the first and second user terminals 10A and 10B 10B may be a user device including a fixed terminal device more generally.
  • OFDMA Orthogonal Frequency Division Multiple Access
  • SC-FDMA Single Carrier-Frequency Division Multiple Access
  • OFDMA is a multi-carrier transmission scheme that performs communication by dividing a frequency band into a plurality of narrow frequency bands (subcarriers) and mapping data to each subcarrier.
  • SC-FDMA is a single carrier transmission method that reduces interference between terminals by dividing a system band into bands each consisting of one or continuous resource blocks for each terminal, and a plurality of terminals using different bands. .
  • the downlink communication channels are PDSCH (Physical Downlink Shared Channel) as downlink data channels shared by the first and second user terminals 10A and 10B, and downlink L1 / L2 control channels (PDCCH, PCFICH, PHICH) Have. Transmission data and higher control information are transmitted by the PDSCH.
  • PDSCH and PUSCH Physical Uplink Shared Channel
  • PDCCH Physical Downlink Control Channel
  • the number of OFDM symbols used for the PDCCH is transmitted by PCFICH (Physical Control Format Indicator Channel).
  • HACH ACK / NACK for PUSCH is transmitted by PHICH (Physical Hybrid-ARQ Indicator Channel).
  • the uplink communication channel includes PUSCH as an uplink data channel shared by the user terminals 10A and 10B and PUCCH as an uplink control channel. Transmission data and higher control information are transmitted by this PUSCH. Also, downlink radio quality information (CQI), ACK / NACK, and the like are transmitted by PUCCH.
  • CQI downlink radio quality information
  • ACK / NACK and the like are transmitted by PUCCH.
  • the overall configuration of the radio base station apparatus will be described with reference to FIG. Note that the radio base station apparatuses 20A and 20B have the same configuration and will be described as the radio base station apparatus 20.
  • the first and second user terminals 10A and 10B have the same configuration and will be described as the user terminal 10.
  • the radio base station apparatus 20 includes transmission / reception antennas 201a and 201b, amplifier sections 202a and 202b, transmission / reception sections 203a and 203b, a baseband signal processing section 204, a call processing section 205, and a transmission path interface 206. ing. Transmission data transmitted from the radio base station apparatus 20 to the user terminal 10 via the downlink is input from the higher station apparatus 30 to the baseband signal processing unit 204 via the transmission path interface 206.
  • the downlink data channel signal is transmitted from the PDCP layer, RDL layer transmission processing such as transmission data division / combination, RLC (Radio Link Control) retransmission control, MAC (Medium Access), and so on.
  • RDL layer transmission processing such as transmission data division / combination, RLC (Radio Link Control) retransmission control, MAC (Medium Access), and so on.
  • Control) Retransmission control for example, HARQ transmission processing, scheduling, transmission format selection, channel coding, inverse fast Fourier transform (IFFT) processing, and precoding processing are performed. Also, transmission processing such as channel coding and inverse fast Fourier transform is performed on the signal of the physical downlink control channel that is the downlink control channel.
  • the baseband signal processing unit 204 notifies the control information for each user terminal 10 to wirelessly communicate with the radio base station apparatus 20 to the user terminals 10 connected to the same cell through the broadcast channel.
  • Information for communication in the cell includes, for example, system information bandwidth in the uplink or downlink, or root sequence identification information (Root Sequence) for generating a random access preamble signal in PRACH (Physical Random Access Channel). Index) and the like.
  • the transmission / reception units 203a and 203b convert the baseband signal output from the baseband signal processing unit 204 into a radio frequency band.
  • the amplifier units 202a and 202b amplify the frequency-converted radio frequency signal and output it to the transmission / reception antennas 201a and 201b.
  • the radio frequency signal received by the transmission / reception antenna 201 is amplified by the amplifier units 202a and 202b, and the frequency is converted by the transmission / reception units 203a and 203b. And converted into a baseband signal and input to the baseband signal processing unit 204.
  • the baseband signal processing unit 204 performs FFT processing, IDFT (Inverse Discrete Fourier Transform) processing, error correction decoding, MAC retransmission control reception processing, RLC layer on transmission data included in the baseband signal received in the uplink , PDCP layer reception processing is performed.
  • the decoded signal is transferred to the higher station apparatus 30 via the transmission path interface 206.
  • the call processing unit 205 performs call processing such as communication channel setting and release, state management of the radio base station apparatus 20, and radio resource management.
  • the user terminal 10 includes a transmission / reception antenna 101, an amplifier unit 102, a transmission / reception unit 103, a baseband signal processing unit 104, and an application unit 105.
  • a radio frequency signal received by the transmission / reception antenna 101 is amplified by the amplifier unit 102, frequency-converted by the transmission / reception unit 103, and converted into a baseband signal.
  • the baseband signal is subjected to FFT processing, error correction decoding, retransmission control reception processing, and the like by the baseband signal processing unit 104.
  • downlink transmission data is transferred to the application unit 105.
  • the application unit 105 performs processing related to layers higher than the physical layer and the MAC layer. Also, the broadcast information in the downlink data is also transferred to the application unit 105.
  • uplink transmission data is input from the application unit 105 to the baseband signal processing unit 104.
  • the baseband signal processing unit 104 performs mapping processing, retransmission control (HARQ) transmission processing, channel coding, DFT processing, and IFFT processing.
  • the transmission / reception unit 103 converts the baseband signal output from the baseband signal processing unit 104 into a radio frequency band. Thereafter, the amplifier unit 102 amplifies the frequency-converted radio frequency signal and transmits it from the transmission / reception antenna 101.
  • HARQ retransmission control
  • the radio base station apparatus shown in FIG. 9 has a centralized control type radio base station configuration.
  • radio resource allocation control such as scheduling is collectively performed in a certain radio base station apparatus (central radio base station apparatus, cell 1 in FIG. 9), and the subordinate radio base station apparatus (remote radio apparatus, FIG. 9).
  • Cell 2 follows the radio resource allocation result of the radio base station apparatus.
  • feedback information CQI is used as information necessary for radio resource allocation among a plurality of cells in the scheduling unit 921 of the radio base station apparatus.
  • each functional block in FIG. 9 mainly relates to the processing contents of the baseband processing unit 204 shown in FIG. Further, the functional block diagram of FIG. 9 is simplified to explain the present invention, and is assumed to have a configuration normally provided in a general baseband processing unit 204.
  • the transmission unit on the concentrated radio base station apparatus (cell 1) side includes a downlink control information generation unit 901, a downlink control information encoding / modulation unit 902, a downlink reference signal generation unit 903, a downlink transmission data generation unit 904, An upper control information generation unit 905 and a downlink transmission data encoding / modulation unit 906 are provided.
  • the transmission unit on the centralized radio base station apparatus (cell 1) side includes a mapping unit 907, a precoding multiplication unit 908, a precoding weight generation unit 909, a downlink channel multiplexing unit 910, and an IFFT unit 911 (911a, 911a, 911b), CP adding section 912 (912a, 912b), transmission amplifier 913 (913a, 913b), transmission antenna 914 (914a, 914b), control channel signal demodulating section 920, user scheduling control section 921, It has.
  • the transmission amplifier 913 and the transmission antenna 914 correspond to the amplifier unit 202 and the transmission / reception antenna 201 shown in FIG. 7, respectively.
  • the transmission unit on the remote radio apparatus (cell 2) side of the subordinate cell includes a downlink control information generation unit 931, a downlink control information encoding / modulation unit 932, a downlink reference signal generation unit 933, and a downlink transmission data generation unit. 934, and a downlink transmission data encoding / modulating unit 936.
  • the transmission unit on the remote radio apparatus (cell 2) side of the subordinate cell includes a mapping unit 937, a precoding multiplication unit 938, a precoding weight generation unit 939, a downlink channel multiplexing unit 940, and IFFT units 941a and 941b.
  • the centralized radio base station device and the remote radio device of the subordinate cell are connected by, for example, an optical fiber.
  • the downlink control information generation units 901 and 931 generate downlink control information under the control of the scheduling unit 921, and output the downlink control information to the downlink control information encoding / modulation units 902 and 932, respectively.
  • Downlink control information coding / modulation sections 902 and 932 perform channel coding and data modulation on the downlink control information, and output them to mapping sections 907 and 937, respectively.
  • Downlink reference signal generation sections 903 and 933 generate downlink reference signals (CRS, CSI-RS, DM-RS) and output the downlink reference signals to mapping sections 907 and 937, respectively.
  • Downlink transmission data generation sections 904 and 934 generate downlink transmission data, and output the downlink transmission data to downlink transmission data encoding / modulation sections 906 and 936, respectively.
  • the higher control information generation section 905 generates higher control information transmitted / received by higher layer signaling (for example, RRC signaling), and outputs the generated higher control information to the downlink transmission data encoding / modulation section 906.
  • the higher control information generation unit 905 generates higher control information including notification of measurement candidate cells, channel quality measurement cells, CoMP transmission transmission cells, and the like to the user terminal 10.
  • the downlink transmission data encoding / modulation section 906 performs channel encoding and data modulation on the downlink transmission data and higher control information, and outputs the result to the mapping section 907.
  • the downlink transmission data encoding / modulation section 936 performs channel encoding and data modulation on the downlink transmission data, and outputs the result to the mapping section 937.
  • the mapping units 907 and 937 map the downlink control information, the downlink reference signal, the downlink transmission data, and the upper control information, and output them to the precoding multipliers 908 and 938, respectively.
  • the precoding weight generation units 909 and 939 generate precoding weights based on the PMI fed back from the user terminal 10 and output the precoding weights to the precoding multiplication units 908 and 938, respectively.
  • each of the precoding weight generation units 909 and 939 includes a codebook, and selects a precoding weight corresponding to PMI from the codebook.
  • the PMI used in precoding weight generation sections 909 and 939 is provided from control channel signal demodulation section 920.
  • the precoding multipliers 908 and 938 multiply the transmission signal by the precoding weight. That is, the precoding multipliers 908 and 938 perform phase shift and / or amplitude shift for each of the transmission antennas 914a and 914b and the transmission antennas 944a and 944b based on the precoding weights given from the precoding weight generation units 909 and 939. Do. Precoding multiplication sections 908 and 938 output the phase-shifted and / or amplitude-shifted transmission signals to downlink channel multiplexing sections 910 and 940, respectively.
  • the downlink channel multiplexing sections 910 and 940 combine the downlink control information, the downlink reference signal, the upper control information, and the downlink transmission data that are phase-shifted and / or amplitude-shifted, for each of the transmission antennas 914a and 914b and the transmission antennas 944a and 944b.
  • a transmission signal is generated.
  • Downlink channel multiplexing sections 910 and 940 output this transmission signal to IFFT (Inverse Fast Fourier Transform) sections 911a and 911b and IFFT sections 941a and 941b, respectively.
  • IFFT Inverse Fast Fourier Transform
  • IFFT sections 911a and 911b and IFFT sections 941a and 941b perform IFFT on the transmission signals and output the transmission signals after IFFT to CP adding sections 912a and 912b and CP adding sections 942a and 942b.
  • CP addition sections 912a and 912b and CP addition sections 942a and 942b add CP (Cyclic Prefix) to the transmission signal after IFFT, and transmit the transmission signal after CP addition to transmission amplifiers 913a and 913b and transmission amplifiers 943a and 943b. Output each.
  • the transmission amplifiers 913a and 913b and the transmission amplifiers 943a and 943b amplify the transmission signal after CP addition.
  • the amplified transmission signals are transmitted from the transmission antennas 914a and 914b and the transmission antennas 944a and 944b to the user terminal 10 on the downlink.
  • the control channel signal demodulator 920 demodulates the control channel signal notified from the user terminal 10 via the PUCCH, outputs the PMI included in the control channel signal to the precoding weight generators 909 and 939, and outputs the CQI to the downlink control information.
  • the data is output to the generation unit 901, the upper control information generation unit 905, and the scheduling unit 921.
  • uplink transmission data demodulation unit (not shown) demodulates uplink transmission data and outputs CQI included in the uplink transmission data to scheduling unit 921.
  • the scheduling report 921 is notified of the measurement report result (RSRP / RSRQ) from the upper layer.
  • the scheduling unit 921 determines a CoMP transmission transmission cell that transmits a shared data channel to the user terminal 10 when CoMP transmission is applied, based on the CQI output from the control channel signal demodulation unit 920 or the like.
  • the scheduling unit 921 includes a variation calculation unit 921a and a metric correction unit 921b.
  • the variation calculator 921a constitutes a calculator, and calculates the degree of CQI variation between transmission points input from the control channel signal demodulator 920 or the like. Then, the calculated degree of variation is output to the metric correction unit 921b.
  • the variation calculation unit 921a calculates the degree of CQI variation between transmission points using, for example, the calculation formulas shown in (Expression 5) and (Expression 6) described above.
  • the metric correction unit 921b constitutes a determination unit, and corrects the scheduling metric according to the degree of variation input from the variation calculation unit 921a. And the user terminal 10 (namely, user terminal 10 which allocates a radio
  • the user terminal 10 to be scheduled is determined using the corrected scheduling metric, and radio resources are allocated to the user terminal 10.
  • the corrected scheduling metric the amount of radio resources allocated to the user terminal 10 having a small degree of CQI variation between transmission points is reduced, while the amount of radio resources allocated to the user terminal 10 having a large degree of variation is increased.
  • the radio base station apparatus shown in FIG. 10 has an autonomous distributed control type radio base station configuration.
  • radio resource allocation control such as scheduling is performed in each of a plurality of radio base station apparatuses.
  • feedback information CQI is used as information necessary for radio resource allocation and the like in user scheduling control units 921 and 951 in a plurality of radio base station apparatuses.
  • each functional block in FIG. 10 mainly relates to the processing contents of the baseband processing unit 204 shown in FIG. Further, the functional block diagram of FIG. 10 is simplified for explaining the present invention, and is assumed to have a configuration normally provided in a general baseband processing unit 204.
  • the same functional blocks as those in FIG. 9 are denoted by the same reference numerals as those in FIG.
  • the transmission unit on the cell 1 side includes a downlink control information generation unit 901, a downlink control information encoding / modulation unit 902, a downlink reference signal generation unit 903, a downlink transmission data generation unit 904, and an upper control information generation unit 905.
  • the transmission unit on the cell 2 side also includes a downlink control information generation unit 931, a downlink control information encoding / modulation unit 932, a downlink reference signal generation unit 933, a downlink transmission data generation unit 934, and higher control information generation.
  • Unit 935 downlink transmission data encoding / modulation unit 936, mapping unit 937, precoding multiplication unit 938, precoding weight generation unit 939, downlink channel multiplexing unit 940, IFFT units 941a and 941b, and CP Additional units 942a and 942b, transmission amplifiers 943a and 943b, transmission antennas 944a and 944b, a control channel signal demodulation unit 950, a scheduling unit 951, and an inter-cell control information transmission / reception unit 952 are provided.
  • control channel signal demodulation unit 950 and the scheduling unit 951 included in the cell 2 side transmission unit are the same as the functions of the control channel signal demodulation unit 920 and the scheduling unit 921 included in the cell 1 side transmission unit, respectively.
  • control channel signal demodulator 950 demodulates the control channel signal notified from the user terminal 10 through the PUCCH, outputs the PMI included in the control channel signal to the precoding weight generator 939, and controls the CQI by user scheduling control. Output to the unit 951.
  • the uplink data channel demodulation unit (not shown) demodulates the uplink transmission data, and outputs the CQI included in the uplink transmission data to the user scheduling control unit 951.
  • the scheduling unit 951 determines a CoMP transmission transmission cell that transmits a shared data channel to the user terminal 10 when CoMP transmission is applied, based on the CQI output from the control channel signal demodulation unit 950 or the like. Similar to the scheduling unit 921, the scheduling unit 951 includes a variation calculation unit 951a and a metric correction unit 951b.
  • the variation calculating unit 951a calculates the degree of CQI variation between transmission points input from the control channel signal demodulating unit 950 or the like, and outputs it to the metric correcting unit 951b.
  • the metric correction unit 951b corrects the scheduling metric according to the degree of variation input from the variation calculation unit 921a. And the user terminal 10 (namely, user terminal 10 which allocates a radio
  • the inter-cell control information transmission / reception units 922 and 952 are connected via, for example, the X2 interface, and transmit / receive timing information and scheduling information output from the scheduling units 921 and 951 to / from each other. Thereby, the cooperation between cells is attained.
  • Each functional block in FIG. 11 mainly relates to the processing contents of the baseband signal processing unit 104 shown in FIG. Further, the functional blocks shown in FIG. 11 are simplified for the purpose of explaining the present invention, and the configuration normally provided in the baseband processing unit is provided.
  • the reception unit of the user terminal 10 includes a CP removal unit 1101, an FFT unit 1102, a downlink channel separation unit 1103, a downlink control information demodulation unit 1104, a downlink transmission data demodulation unit 1105, a channel estimation unit 1106, a channel quality A measurement unit 1107, a PMI selection unit 1108, and a feedback information generation unit 1109 are provided.
  • the transmission signal transmitted from the radio base station apparatus eNB is received by the transmission / reception antenna 101 illustrated in FIG. 8 and output to the CP removal unit 1101.
  • CP removing section 1101 removes the CP from the received signal and outputs it to FFT section 1102.
  • the FFT unit 1102 performs fast Fourier transform (FFT) on the signal after CP removal, and converts the signal in the time domain into a signal in the frequency domain.
  • FFT section 1102 outputs the signal converted to the frequency domain signal to downlink channel separation section 1103.
  • the downlink channel separator 1103 separates the downlink channel signal into downlink control information, downlink transmission data, higher control information, and downlink reference signals.
  • Downlink channel separation section 1103 outputs downlink control information to downlink control information demodulation section 1104, outputs downlink transmission data and higher control information to downlink transmission data demodulation section 1105, and outputs a downlink reference signal to channel estimation section 1106. .
  • the downlink control information demodulator 1104 demodulates the downlink control information, and outputs the demodulated control information to the downlink transmission data demodulator 1105 and the channel quality measurement unit 1107. Further, the downlink control information demodulation section 1104 demodulates a control channel signal (for example, PDCCH) included in the downlink control information. Downlink transmission data demodulation section 1105 demodulates downlink transmission data using the control information. Also, downlink transmission data demodulation section 1105 demodulates higher-level control information included in downlink transmission data and notifies channel quality measurement section 1107.
  • Channel estimation section 1106 estimates the channel state using the downlink reference signal, and outputs the estimated channel state to channel quality measurement section 1107 and PMI selection section 1108.
  • the channel quality measurement unit 1107 is configured to determine the RSRP / RSR from the channel state notified from the channel estimation unit 1106 based on the upper control information notified from the downlink transmission data demodulation unit 1105 and the control information notified from the downlink control information demodulation unit 1104. Measure RSRQ and CQI. For example, the channel quality measurement unit 1107 measures the RSRP / RSRQ and CQI of all the channel quality measurement cells 111 specified by the radio base station apparatus 20. The RSRP / RSRQ and CQI measured by the channel quality measurement unit 1107 are output to the feedback information generation unit 1109 as feedback information.
  • the PMI selection unit 1108 selects a PMI from the channel state notified from the channel estimation unit 1106 using a code book.
  • the PMI selected by the PMI selection unit 1108 is output to the feedback information generation unit 1109 as feedback information.
  • the feedback information generation unit 1109 feeds back the RSRP / RSRQ and CQI measured by the channel quality measurement unit 1107 to the radio base station apparatus 20 as feedback information. For example, the RSRP / RSRQ and CQI of all channel quality measurement cells 111 specified by the radio base station apparatus 20 are fed back to the radio base station apparatus 20.
  • the radio communication system 1 includes a plurality of radio base station apparatuses 20 and user terminals 10 configured to be able to perform CoMP transmission / reception with the plurality of radio base station apparatuses 20.
  • the user terminal 10 transmits feedback information (for example, CQI) for each transmission point of CoMP transmission.
  • the radio base station apparatus 20 calculates a variation degree of feedback information between transmission points of CoMP transmission fed back from the user terminal 10, and determines a radio resource to be allocated to the user terminal 10 according to the calculated variation degree. .
  • the radio base station apparatus 20 calculates the degree of CQI variation of feedback information between transmission points fed back from the user terminal 10 and assigns it to the user terminal 10 according to the calculated degree of variation. Radio resources are determined. Thereby, since it is possible to avoid a situation in which radio resources are excessively allocated to the cell edge UE when performing CoMP transmission from the radio base station apparatus 20, it is possible to improve the throughput characteristics of the entire system and the user terminal UE at the cell edge. .
  • this invention is not limited to description of a specification, It can implement by changing variously.
  • a case has been described in which the degree of CQI variation between transmission points fed back from the user terminal UE is calculated in the process in which the radio base station apparatus eNB determines a CoMP transmission transmission cell.
  • the feedback information for calculating the degree of variation is not limited to this, and can be changed as appropriate.
  • measurement candidate cells 110 cells specified by RRM measurement set
  • channel quality measurement cells 111 cells specified by CoMP measurement set
  • CoMP transmission transmission cells fed back from user terminal UE RSRP / RSRQ between 112 (CoMP transmission points) can also be used.
  • the CoMP transmission is performed from the radio base station apparatus eNB as in the case where the scheduling metric is corrected according to the CQI variation degree.
  • the connection relations and functions of the components shown in the present specification can be implemented with appropriate changes.
  • the structures described in this specification can be implemented in appropriate combination.
  • the present invention can be implemented with appropriate modifications without departing from the scope of the present invention.

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

Abstract

La présente invention améliore la propriété de débit d'un système entier et d'un équipement utilisateur (UE) au niveau d'un bord de cellule durant une transmission CoMP. Ce système de communication sans fil est caractérisé par le fait : qu'il comprend une pluralité de dispositifs de station de base sans fil, et un équipement utilisateur qui est configuré afin d'être capable d'une transmission et d'une réception multipoint coordonnées avec la pluralité de dispositifs de station de base sans fil ; que l'équipement utilisateur transmet des informations de rétroaction par rapport à chaque point de transmission de la transmission multipoint coordonnée (S23) ; que les dispositifs de station de base sans fil calculent le degré de variance des informations de rétroaction parmi les points de transmission de la transmission multipoint coordonnée, lesdites informations de rétroaction étant renvoyées par l'équipement utilisateur (S24) ; et qu'une ressource sans fil est déterminée pour une affectation à l'équipement utilisateur en fonction du degré de variance calculé (S25).
PCT/JP2013/084407 2012-12-27 2013-12-24 Dispositif de station de base sans fil, système de communication sans fil, et procédé de communication sans fil WO2014103978A1 (fr)

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JP6398612B2 (ja) 2014-10-29 2018-10-03 富士通株式会社 基地局及びセル選択方法
JP6586736B2 (ja) * 2015-02-20 2019-10-09 富士通株式会社 制御装置、協調パターン選択方法、及び無線通信システム
JP6457409B2 (ja) * 2015-03-31 2019-01-23 日本電信電話株式会社 スケジューリング装置および方法

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WO2012081150A1 (fr) * 2010-12-17 2012-06-21 日本電気株式会社 Dispositif de contrôle de paramètre sans fil, dispositif formant station de base, procédé de contrôle de paramètre sans fil et support lisible par un ordinateur non transitoire

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WO2012081150A1 (fr) * 2010-12-17 2012-06-21 日本電気株式会社 Dispositif de contrôle de paramètre sans fil, dispositif formant station de base, procédé de contrôle de paramètre sans fil et support lisible par un ordinateur non transitoire

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