WO2010137665A1 - 無線通信システム、無線端末、無線基地局及び無線通信方法 - Google Patents
無線通信システム、無線端末、無線基地局及び無線通信方法 Download PDFInfo
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- WO2010137665A1 WO2010137665A1 PCT/JP2010/059041 JP2010059041W WO2010137665A1 WO 2010137665 A1 WO2010137665 A1 WO 2010137665A1 JP 2010059041 W JP2010059041 W JP 2010059041W WO 2010137665 A1 WO2010137665 A1 WO 2010137665A1
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- base station
- radio
- radio base
- terminal
- wireless
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B7/00—Radio transmission systems, i.e. using radiation field
- H04B7/02—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas
- H04B7/04—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas
- H04B7/0413—MIMO systems
- H04B7/0417—Feedback systems
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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
- H04B7/022—Site diversity; Macro-diversity
- H04B7/024—Co-operative use of antennas of several sites, e.g. in co-ordinated multipoint or co-operative multiple-input multiple-output [MIMO] systems
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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
- H04B7/028—Spatial transmit diversity using a single antenna at the transmitter
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B7/00—Radio transmission systems, i.e. using radiation field
- H04B7/02—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas
- H04B7/04—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas
- H04B7/06—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the transmitting station
- H04B7/0613—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the transmitting station using simultaneous transmission
- H04B7/0615—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the transmitting station using simultaneous transmission of weighted versions of same signal
- H04B7/0619—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the transmitting station using simultaneous transmission of weighted versions of same signal using feedback from receiving side
- H04B7/0658—Feedback reduction
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04W—WIRELESS COMMUNICATION NETWORKS
- H04W28/00—Network traffic management; Network resource management
- H04W28/02—Traffic management, e.g. flow control or congestion control
- H04W28/06—Optimizing the usage of the radio link, e.g. header compression, information sizing, discarding information
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B7/00—Radio transmission systems, i.e. using radiation field
- H04B7/02—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas
- H04B7/04—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas
- H04B7/06—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the transmitting station
- H04B7/0613—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the transmitting station using simultaneous transmission
- H04B7/0615—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the transmitting station using simultaneous transmission of weighted versions of same signal
- H04B7/0619—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the transmitting station using simultaneous transmission of weighted versions of same signal using feedback from receiving side
- H04B7/0621—Feedback content
- H04B7/0634—Antenna weights or vector/matrix coefficients
Definitions
- the present invention relates to a wireless communication system, a wireless terminal, a wireless base station, and a wireless communication method to which inter-base station cooperative MIMO communication is applied.
- a wireless signal transmission side and a reception side each use a plurality of antennas and transmit a plurality of signal sequences at the same frequency and the same time.
- MIMO Multi-Input Multi-Output
- the reception side of the radio signal generates propagation path information corresponding to the characteristics of the wireless propagation path (hereinafter referred to as propagation path characteristics), and feeds back the propagation path information to the transmission side.
- propagation path characteristics characteristics of the wireless propagation path
- feedback of propagation path information is essential.
- a control channel for feedback is set only between one radio base station among a plurality of radio base stations, and feedback from the one radio base station to another radio base station using inter-base station communication
- inter-base station communication By transferring, overhead associated with feedback can be reduced.
- the feedback may not be in time due to the effect of transfer delay, and inter-base station cooperative MIMO communication may not function normally.
- an object of the present invention is to provide a radio communication system, a radio terminal, a radio base station, and a radio communication method capable of reducing overhead caused by feedback while causing the inter-base station cooperative MIMO communication to function normally.
- the first feature of the present invention is a radio terminal (radio terminal UE) and a first radio base station that transmits a first radio signal (radio signal RS1) to the radio terminal in response to feedback from the radio terminal.
- Wireless base station wireless base station BS2
- the wireless terminal transmits the first wireless base station
- the gist of the present invention is that the wireless communication system (wireless communication system 1) omits feedback.
- a second feature of the present invention relates to the first feature of the present invention.
- the wireless terminal omits feedback to the first wireless base station, and First propagation path information (propagation path information 1) according to propagation path characteristics from one radio base station to the radio terminal, and second propagation according to propagation path characteristics from the second radio base station to the radio terminal.
- the gist is that feedback based on route information (propagation route information 2) is performed on the second radio base station.
- a third feature of the present invention according to the second feature of the present invention is that, when the number of transmission antennas is one, the wireless terminal omits feedback to the first wireless base station, and The gist is to normalize the second propagation path information with reference to one propagation path information, and to feed back the normalized second propagation path information to the second radio base station.
- a fourth feature of the present invention according to the second feature of the present invention is that, when the number of transmission antennas is one, the wireless terminal omits feedback to the first wireless base station, and 1 channel information and the 2nd channel information are fed back to the second radio base station, and the second radio base station uses the first channel information fed back from the radio terminal as a reference and the radio terminal
- the second aspect is to normalize the second propagation path information fed back from and transmit the second radio signal in accordance with the normalized second propagation path information.
- a fifth feature of the present invention relates to the second feature of the present invention, wherein the first propagation path information is a propagation path characteristic between a transmission antenna of the first radio base station and a reception antenna of the radio terminal.
- the second propagation path information is information indicating propagation path characteristics between the transmission antenna of the second radio base station and the reception antenna of the radio terminal.
- a sixth feature of the present invention relates to the second feature of the present invention, wherein the first propagation path information is a first transmission antenna weight (used for controlling at least one of a phase and an amplitude of the first radio signal). Transmission antenna weight 1) or an index indicating the first transmission antenna weight, and the second propagation path information is a second transmission antenna weight used for controlling at least one of the phase and the amplitude of the second radio signal.
- the gist of the present invention is (transmitting antenna weight 2) or an index indicating the second transmitting antenna weight.
- a seventh feature of the present invention relates to the first feature of the present invention, wherein the wireless terminal measures the reception quality or propagation path characteristic of the first wireless signal for each transmission antenna of the first wireless base station.
- the first radio base station transmits the first radio signal to the radio terminal using the one transmission antenna selected according to the measured reception quality or the measured propagation path characteristic.
- the gist is to do.
- An eighth feature of the present invention relates to the first feature of the present invention, wherein the first radio base station from which feedback from the radio terminal is omitted is closer to the radio terminal than the second radio base station.
- the gist is that it is a radio base station located far away.
- a ninth feature of the present invention relates to the first feature of the present invention, wherein the first radio base station from which feedback from the radio terminal is omitted has a higher processing performance than the second radio base station.
- the gist is that it is a base station.
- a tenth feature of the present invention relates to the first feature of the present invention, wherein the first radio base station that does not require feedback from the radio terminal has a lower processing performance than the second radio base station.
- the gist is that it is a base station.
- An eleventh feature of the present invention relates to the first feature of the present invention, wherein the first radio base station from which feedback from the radio terminal is omitted is more inclusive of the radio terminal than the second radio base station.
- the gist of the present invention is that it is a radio base station with small propagation path fluctuations.
- a twelfth feature of the present invention relates to the first feature of the present invention, wherein the first radio base station from which feedback from the radio terminal is omitted is more inclusive of the radio terminal than the second radio base station.
- the main point is that the wireless base station has a large propagation path loss.
- the thirteenth feature of the present invention is that the first radio signal (radio signal RS1) is received from the first radio base station (radio base station BS1), and the second radio signal is transmitted at the same frequency and the same time as the first radio signal.
- a receiver that receives a radio signal (radio signal RS2) from a second radio base station (radio base station BS2), and transmits feedback to the first radio base station and the second radio base station.
- the transmission unit (transmission unit 122) has one transmission antenna used for transmission of the first radio signal in the first radio base station
- the transmission unit communicates with the first radio base station.
- the gist is that the wireless terminal (radio terminal UE) omits feedback.
- a fourteenth feature of the present invention is a first radio base station (radio base station BS1) that transmits a first radio signal (radio signal RS1) to the radio terminal in response to feedback from a radio terminal (radio terminal UE).
- a second radio base station (radio base station) transmits a second radio signal (radio signal RS2) to the radio terminal at the same frequency and at the same time as the first radio signal.
- BS2 the first radio base station or the second radio base station uses the first radio base station to transmit the first radio signal in the first radio base station.
- the gist is to instruct the wireless terminal to omit feedback to the wireless base station.
- a fifteenth feature of the present invention is that an instruction unit (control unit 230 or control) that instructs a radio terminal (radio terminal UE) to omit feedback for a predetermined radio base station when cooperative communication between base stations is being performed.
- the gist of the present invention is that it is a radio base station comprising the unit 330).
- a sixteenth feature of the present invention relates to the fifteenth feature of the present invention, wherein the predetermined radio base station is located farther from the radio terminal than other radio base stations other than the predetermined radio base station.
- the predetermined radio base station is located farther from the radio terminal than other radio base stations other than the predetermined radio base station.
- a radio base station a radio base station having a higher processing performance than the other radio base station, a radio base station having a lower processing performance than the other radio base station, and the radio terminal than the other radio base station
- the main point is that the wireless base station has a small propagation path fluctuation, or a wireless base station that has a larger propagation path loss with the wireless terminal than the other wireless base stations.
- a seventeenth feature of the present invention is that a first radio base station (radio base station BS1) transmits a first radio signal to the radio terminal in response to feedback from a radio terminal (radio terminal UE); In response to feedback from the terminal, a second radio base station (radio base station BS2) transmits a second radio signal to the radio terminal at the same frequency and at the same time as the first radio signal;
- a wireless communication method comprising: a step of omitting feedback to the first wireless base station when the wireless terminal uses one transmission antenna for transmitting the first wireless signal in one wireless base station; Is the gist.
- a radio communication system a radio terminal, a radio base station, and a radio communication method that can reduce the overhead associated with feedback while normally functioning cooperative MIMO communication between base stations.
- the 2). 3 is a flowchart showing an operation of the radio communication system according to the first embodiment of the present invention. It is a block diagram which shows the structure of the radio
- FIG. 1 is a schematic configuration diagram of a radio communication system 1 in which inter-base station cooperative MIMO communication (multi-cell coordinated transmission / reception or multi-point coordinated transmission / reception (CoMP)) is introduced.
- inter-base station cooperative MIMO communication multi-cell coordinated transmission / reception or multi-point coordinated transmission / reception (CoMP)
- the wireless communication system 1 has a configuration based on LTE-Advanced, which is positioned as a fourth generation (4G) mobile phone system, for example.
- the wireless communication system 1 employs an FDD (Frequency Division Duplex) method as a duplex method.
- FDD Frequency Division Duplex
- the radio communication system 1 includes a radio base station BS1 (first radio base station), a radio base station BS2 (second radio base station), a radio terminal UE, and a control device 11.
- the radio terminal UE is located in an overlapping portion between the cell C1 formed by the radio base station BS1 and the cell C2 formed by the radio base station BS2.
- the radio base station BS1 and the radio base station BS2 may be macro cell base stations or femto cell base stations.
- a femtocell base station is a small radio base station installed mainly indoors.
- the radio base station BS1 and the radio base station BS2 are connected to each other via a backhaul network 10 which is a wired communication network.
- the control device 11 is provided in the backhaul network 10 and controls the radio base station BS1 and the radio base station BS2 via the backhaul network 10.
- the radio base station BS1 and the radio base station BS2 can directly perform communication between base stations without going through the control device 11.
- Closed loop control is introduced in the cooperative MIMO communication between base stations in the wireless communication system 1.
- the radio base station BS1 transmits a radio signal RS1 (first radio signal) to the radio terminal UE in response to feedback from the radio terminal UE.
- the radio base station BS2 transmits the radio signal RS2 (second radio signal) to the radio terminal UE at the same frequency and the same time as the radio signal RS1.
- the radio base station BS1 performs a weighting process (referred to as “precoding”) of the transmission signal in accordance with feedback from the radio terminal UE, and transmits a radio signal RS1 including the weighted transmission signal.
- precoding a weighting process
- the phase and amplitude of the transmission signal are controlled for each transmission antenna of the radio base station BS1.
- the radio base station BS2 performs a weighting process on the transmission signal in accordance with the feedback from the radio terminal UE, and transmits the radio signal RS2 corresponding to the weighted transmission signal.
- the weighting process the phase and amplitude of the transmission signal (radio signal RS2) are controlled for each transmission antenna of the radio base station BS2.
- the transmission signal sequence (also referred to as “stream”) included in the radio signal RS1 transmitted by the radio base station BS1 is the same as the transmission signal sequence included in the radio signal RS2 transmitted by the radio base station BS2. It may be different.
- the reception quality included in the radio signal RS1 and the transmission signal sequence included in the radio signal RS2 are the same (during single stream transmission), the reception quality is improved due to the diversity effect.
- the radio terminal UE is located at the cell edge of the radio base station BS1 and the radio base station BS2, it is preferable to improve the reception quality by single stream transmission.
- the transmission speed included in the radio signal RS1 and the transmission signal sequence included in the radio signal RS2 are different (during multi-stream transmission), the transmission speed is improved.
- the radio base station BS1 or the radio base station BS2 is, for example, a femtocell base station and the radio terminal UE is located near the radio base station BS1 and the radio base station BS2, the transmission rate is increased by multi-stream transmission. It is preferable to improve.
- the radio terminal UE When the radio base station BS1 uses one transmission antenna for transmitting the radio signal RS1, the radio terminal UE omits feedback to the radio base station BS1. In the following, a case where feedback to the radio base station BS1 is omitted will be described, but a radio base station from which feedback is omitted can be selected. A method for selecting a radio base station for which feedback is omitted will be described later.
- the radio terminal UE omits feedback to the radio base station BS1, and also propagates channel information 1 (first channel information) according to the channel characteristics from the radio base station BS1 to the radio terminal UE, and the radio base station BS2. To the radio base station BS2 based on the propagation path information 2 (second propagation path information) corresponding to the propagation path characteristics from the radio terminal UE to the radio terminal UE.
- the propagation path characteristic means parameters such as an attenuation amount, a phase rotation amount, and a delay amount that are received when a wireless signal passes through the wireless propagation path.
- FIG. 2 is a block diagram showing the configuration of the radio terminal UE.
- the radio terminal UE may have a configuration (such as a power supply unit) that is not illustrated or omitted in the description.
- the radio terminal UE includes a plurality of antennas 111, a transmission / reception unit 120, a control unit 130, and a storage unit 140.
- the radio terminal UE has a plurality of antennas 111, but it is not always necessary to have a plurality of antennas 111, and only one antenna 111 may be provided.
- the transmission / reception unit 120 is configured using, for example, a radio frequency (RF) circuit or a baseband (BB) circuit.
- the control unit 130 is configured using, for example, a CPU, and controls various functions provided in the radio terminal UE.
- the storage unit 140 is configured using a memory, for example, and stores various types of information used for controlling the radio terminal UE and the like.
- the transmission / reception unit 120 includes a reception unit 121 and a transmission unit 122.
- the control unit 130 includes a propagation path information generation unit 131 and a normalization unit 132.
- the receiving unit 121 receives the radio signal RS1 from the radio base station BS1 and also receives the radio signal RS2 from the radio base station BS2. Note that, at the time of single stream transmission or the like, the reception unit 121 preferably receives the radio signal RS1 and the radio signal RS2 in the same phase.
- the propagation path information generation unit 131 uses a reference signal (pilot signal) included in the radio signal RS1 received by the reception unit 121 and the like between each transmission antenna of the radio base station BS1 and each reception antenna of the radio terminal UE.
- the process (what is called channel estimation) which calculates the propagation path estimated value (henceforth, propagation path estimated value 1) which shows a propagation path characteristic is performed.
- the propagation path information generation unit 131 uses a reference signal (pilot signal) included in the radio signal RS2 received by the reception unit 121, between each transmission antenna of the radio base station BS2 and each reception antenna of the radio terminal UE.
- a process of calculating a propagation path estimation value (hereinafter, propagation path estimation value 2) indicating the propagation path characteristics is performed.
- the propagation path information generation unit 131 generates propagation path information 1 that is information to be fed back to the radio base station BS1 based on the propagation path estimated value 1.
- the transmission path information 1 is not limited to the case where the propagation path estimation value 1 is used as the propagation path information 1.
- the transmission path information 1 is used for weighting processing (that is, control of at least one of the phase and the amplitude of the radio signal RS1) in the radio base station BS1. It may be an antenna weight 1 or an index indicating the transmission antenna weight 1 (referred to as “PMI (Pre-coding Matrix Index)”).
- the propagation path information generation unit 131 generates propagation path information 2 that is information to be fed back to the radio base station BS2 based on the propagation path estimation value 2.
- the propagation path information 2 is not limited to the case where the propagation path estimated value 2 is used as the propagation path information 2, and the transmission path information 2 is used for weighting processing (that is, control of at least one of the phase and the amplitude of the radio signal RS 2) in the radio base station BS 2. It may be an antenna weight 2 or an index indicating the transmission antenna weight 2.
- the normalization unit 132 normalizes the propagation path information 2 on the basis of the propagation path information 1 when the radio base station BS1 uses one transmission antenna for transmission of the radio signal RS1. Details of the normalization process will be described later.
- the transmission unit 122 transmits feedback to the radio base station BS1 and the radio base station BS2.
- the transmission unit 122 uses one transmission antenna to transmit the radio signal RS1
- the transmission unit 122 omits the feedback of the propagation path information 1 to the radio base station BS1 and is normalized by the normalization unit 132
- the transmitted propagation path information 2 is fed back to the radio base station BS2.
- the transmission unit 122 feeds back the propagation path information 1 to the radio base station BS1, and the propagation path information 2 to the radio base station BS2. Feedback may be provided.
- FIG. 3 is a block diagram showing a configuration of the radio base station BS1.
- the radio base station BS1 includes a plurality of antennas 211, a transmission / reception unit 220, a control unit 230, a storage unit 240, and a wired communication unit 250.
- the radio base station BS ⁇ b> 1 has a plurality of antennas 211, but it is not always necessary to have a plurality of antennas 211, and only one antenna 211 may be provided.
- the transmission / reception unit 220 is configured using, for example, an RF circuit, a BB circuit, or the like.
- the control unit 230 is configured using a CPU, for example, and controls various functions provided in the radio base station BS1.
- the storage unit 240 is configured using, for example, a memory, and stores various types of information used for controlling the radio base station BS1.
- the wired communication unit 250 communicates with the radio base station BS2 and the control device 11 via the backhaul network 10.
- the transmission / reception unit 220 includes a reception unit 221 and a transmission unit 222.
- the control unit 230 includes a weight control unit 231.
- the reception unit 221 receives the fed back propagation path information 1.
- the weight control unit 231 controls the transmission antenna weight 1 used for transmission of the radio signal RS1.
- the weight control unit 231 notifies the transmission unit 222 of the transmission antenna weight 1 corresponding to the propagation path information 1.
- the weight control unit 231 does not notify the transmission unit weight 1 to the transmission unit 222 or is determined in advance.
- the transmission unit 222 is notified of the fixed transmission antenna weight 1.
- the transmission unit 222 weights (precodes) the transmission signal using the transmission antenna weight 1 notified from the weight control unit 231 and transmits the radio signal RS1 including the weighted transmission signal.
- the transmission unit 222 transmits the radio signal RS1 including the transmission signal without weighting.
- FIG. 4 is a block diagram showing the configuration of the radio base station BS2.
- the radio base station BS2 includes a plurality of antennas 311, a transmission / reception unit 320, a control unit 330, a storage unit 340, and a wired communication unit 350.
- the radio base station BS ⁇ b> 2 has a plurality of antennas 211, but it is not always necessary to have a plurality of antennas 211, and only one antenna 211 may be provided.
- the transmission / reception unit 320 is configured using, for example, an RF circuit or a BB circuit.
- the control unit 330 is configured using, for example, a CPU, and controls various functions provided in the radio base station BS2.
- the storage unit 340 is configured using, for example, a memory, and stores various types of information used for controlling the radio base station BS2.
- the wired communication unit 350 communicates with the radio base station BS1 and the control device 11 via the backhaul network 10.
- the transmission / reception unit 320 includes a reception unit 321 and a transmission unit 322.
- the control unit 330 includes a weight control unit 331.
- the receiving unit 321 receives the propagation path information 2 fed back from the radio terminal UE.
- the propagation path information 2 received by the receiving unit 321 may be normalized or not normalized.
- the weight control unit 331 controls the transmission antenna weight 2 used for transmission of the radio signal RS2.
- the weight control unit 331 notifies the transmission unit 322 of the transmission antenna weight 2 corresponding to the propagation path information 2 received by the reception unit 321.
- the transmission unit 322 weights (precodes) the transmission signal using the transmission antenna weight 2 notified from the weight control unit 331, and transmits the radio signal RS2 including the weighted transmission signal.
- the transmission unit 322 transmits the radio signal RS2 including the transmission signal without weighting.
- the propagation path estimation value has a value for each antenna (for each combination of transmission and reception antennas), but if the relative relationship is maintained, even if the value itself is changed, it is processed appropriately on the receiving side (signal separation, etc.) it can.
- the propagation path estimated value 1 (a, b) and the propagation path estimated value 2 (c, d) shown in FIG. 5 (a) as shown in FIG. 5 (b), (a x e, b x ⁇ e, c x e, d x e)
- the phase relationship between the propagation path estimation value 1 and the propagation path estimation value 2 is maintained. Since the same phase relationship is maintained, there is no particular problem.
- each of the propagation path estimation value 1 (a) and the propagation path estimation value 2b (b, c, d) As shown in FIG. 6B, the channel estimation value 2 is divided by the channel estimation value 1 for what feedback is necessary. Specifically, propagation path estimation value 1 (a ⁇ ⁇ / a) (1) and propagation path estimation value 2 (b / a, c / a, d / ⁇ a) are normalized by division to estimate propagation path The value 1 can be virtually always fixed to (1), and feedback to the radio base station BS1 can be made unnecessary.
- normalization is performed by dividing the channel estimation value 2 by the channel estimation value 1, but any other calculation method can be used as long as the relative relationship between the channel estimation value 1 and the channel estimation value 2 is maintained.
- normalization may be performed by subtracting the propagation path estimated value 1 from the propagation path estimated value 2.
- the propagation path information 1 is the transmission antenna weight 1 or its index and the propagation path information 2 is the transmission antenna weight 2 or its index
- a candidate for the transmission antenna weight 2 is selected from the “codebook”), and the selected transmission antenna weight 2 or its index is fed back to the radio base station BS2.
- the following method may be employed as a method for selecting an optimum PMI from a list (code book) of an index (herein referred to as “PMI”) of the transmission antenna weight 2.
- PMI an index
- the reception SNR when the PMI in the list is used is calculated for each PMI, and the maximum reception among the calculated reception SNRs.
- the PMI corresponding to the SNR is selected as the optimum PMI.
- Such a method is effective when the PMI in the list is small.
- the normalization unit 132 receives the signal based on the channel estimation value 1 and the channel estimation value 2 on the assumption that the radio base station BS1 performs fixed transmission with one antenna.
- the PMI having the maximum SNR is selected (searched) as the PMI to be fed back to the radio base station BS2.
- the base station selection process may be executed by any of the radio terminal UE, the radio base station BS1, the radio base station BS2, and the control device 11.
- any of the following selection methods 1 to 5 can be used.
- the selection methods 1 to 5 are not limited to be used in a fixed manner, and the selection methods 1 to 5 are appropriately switched depending on the situation of the radio terminal UE, the radio base station BS1, and the radio base station BS2. May be.
- Selection method 1 In the selection method 1, a radio base station located far from the radio terminal UE is selected as the radio base station BS1, and a radio base station located close to the radio terminal UE is selected as the radio base station BS2. As a result, the radio terminal UE performs feedback to the radio base station BS2 located close to the radio terminal UE, and omits feedback to the radio base station BS1 located far from the radio terminal UE. Transmission power can be reduced, and the amount of interference can be reduced.
- the selection method 1 is preferable when the battery level of the radio terminal UE is low.
- the selection method 1 information on the distance between the radio terminal UE and the radio base station BS1 and the distance between the radio terminal UE and the radio base station BS2 are required, but the information is provided in the radio terminal UE.
- Distance information can be obtained using GPS or the like.
- Selection method 2 In the selection method 2, a radio base station with high processing performance (specifically, a macro cell base station) is selected as the radio base station BS1, and a radio base station with low processing performance (specifically, a femtocell base station) Is selected as the radio base station BS2.
- a radio base station with high processing performance specifically, a macro cell base station
- a radio base station with low processing performance specifically, a femtocell base station
- the radio terminal UE performs feedback to the radio base station BS2 located near from the radio terminal UE, and a radio located far from the radio terminal UE. Feedback to the base station BS1 can be omitted.
- the selection method 2 is effective.
- Selection method 3 a radio base station with low processing performance (specifically, a femtocell base station) is selected as the radio base station BS1, and a radio base station with high processing performance (specifically, a macrocell base station) is selected. Is selected as the radio base station BS2. Since a high-speed transmission rate can be obtained by causing a radio base station with low processing performance to perform constant transmission of one antenna and causing a radio base station with high processing performance to perform multi-stream multi-stream transmission, a selection method 3 is effective when a high transmission rate is required or when the battery of the radio terminal UE is high.
- Selection method 4 In the selection method 4, a radio base station having a small propagation path fluctuation with the radio terminal UE is selected as the radio base station BS1, and a radio base station having a large propagation path fluctuation with the radio terminal UE is selected as the radio base station BS2. Choose as. This is because the radio base station BS1 performs constant transmission of one antenna, and therefore it is preferable that the propagation path fluctuation is small. Selection method 4 is effective when there is a large difference in propagation path fluctuation with each radio base station.
- Selection method 5 In the selection method 5, a radio base station having a large propagation path loss with the radio terminal UE is selected as the radio base station BS1, and a radio base station having a small propagation path loss with the radio terminal UE is selected as the radio base station BS2. Choose as.
- the propagation path loss is calculated as the difference between the transmission power at the radio base station and the reception power at the radio terminal UE, and reflects the distance between the terminal and the base station. For this reason, the radio terminal UE can perform feedback to the radio base station BS2 located close to the radio terminal UE, and can omit feedback to the radio base station BS1 located far from the radio terminal UE. Since the propagation path loss is used for other purposes such as transmission power control and can be easily obtained, the selection method 5 can effectively utilize the existing system configuration.
- antenna selection processing that is processing for selecting one transmission antenna used for transmission of the radio signal RS1 from the plurality of antennas 211 of the radio base station BS1 will be described.
- the radio base station BS1 transmits a radio signal RS1 using all the antennas 211.
- the radio terminal UE measures the reception quality (such as SNR) or propagation path characteristics of the radio signal RS1 for each transmission antenna (antenna 211) of the radio base station BS1.
- the radio terminal UE or the radio base station BS1 selects one transmission antenna with the best measured reception quality or measured propagation path characteristics. Then, the radio base station BS1 transmits the radio signal RS1 to the radio terminal UE using the selected one transmission antenna. Thereby, communication quality can be improved.
- control device 11 may execute the process of selecting one transmission antenna with the best measured reception quality or measured propagation path characteristics.
- the antenna selection process may be executed at predetermined time intervals. In this case, feedback to the radio base station BS1 occurs every time the transmission antenna of the radio base station BS1 is selected. However, the communication quality can be further improved by selecting the optimum antenna.
- step S11 the radio base station BS1 from which feedback is omitted is selected by the process described in the above (3) base station selection process.
- an apparatus other than the radio terminal UE radio base station BS1, radio base station BS2, control apparatus 11
- the apparatus transmits a propagation path to the radio base station BS1.
- the radio terminal UE is instructed to omit feedback of information 1.
- step S12 one transmission antenna used for transmission of the radio signal RS1 is selected from the plurality of antennas 211 of the radio base station BS1 by the process described in the above (4) antenna selection process. Then, the radio base station BS1 transmits the radio signal RS1 using the selected one transmission antenna. The radio base station BS2 transmits a radio signal RS2 using one or a plurality of antennas 311. The receiving unit 121 of the radio terminal UE receives the radio signal RS1 from the radio base station BS1 and also receives the radio signal RS2 from the radio base station BS2.
- step S13 the propagation path information generation unit 131 of the radio terminal UE generates propagation path information 1 and propagation path information 2.
- the normalization unit 132 normalizes the propagation path information 2 based on the propagation path information 1 by the process described in the above (2) normalization process.
- step S14 the transmission unit 122 of the radio terminal UE omits feedback of the propagation path information 1 to the radio base station BS1, and feeds back the propagation path information 2 normalized by the normalization unit 132 to the radio base station BS2. To do.
- the receiving unit 321 of the radio base station BS2 receives the normalized propagation path information 2.
- the weight control unit 331 of the radio base station BS2 notifies the transmission unit 322 of the transmission antenna weight 2 corresponding to the propagation path information 2 received by the reception unit 321.
- step S15 the transmission unit 322 of the radio base station BS2 weights (precodes) the transmission signal using the transmission antenna weight 2 notified from the weight control unit 331, and receives the radio signal RS2 including the weighted transmission signal. Send.
- the transmission unit 222 of the radio base station BS1 constantly transmits the radio signal RS1 including the transmission signal using one transmission antenna.
- the radio terminal UE omits feedback to the radio base station BS1. Thereby, the overhead accompanying feedback can be reduced. That is, since the radio terminal UE only needs to set a control channel for feedback with the radio base station BS2, consumption of radio resources in the uplink is reduced.
- the radio terminal UE normalizes the propagation path information 2 on the basis of the propagation path information 1 and feeds back the normalized propagation path information 2 to the radio base station BS2.
- the radio base station BS2 since the radio base station BS2 transmits the radio signal RS2 according to the propagation path information 2 in which the relative relationship with the propagation path information 1 is maintained, feedback to the radio base station BS1 is omitted. Even so, the inter-base station cooperative MIMO communication can function normally.
- the radio terminal UE normalizes the propagation path information.
- the radio base station BS2 normalizes the propagation path information.
- (1) the configuration of the wireless communication system, (2) the operation of the wireless communication system, and (3) the effects of the second embodiment will be described. However, differences from the first embodiment will be described.
- FIG. 8 is a block diagram illustrating a configuration of a radio terminal UE according to the second embodiment.
- FIG. 9 is a block diagram showing a configuration of the radio base station BS2 according to the second embodiment.
- the radio terminal UE does not have the normalization unit 132 described in the first embodiment.
- the radio base station BS2 has a normalization unit 332 having the same function as the normalization unit 132 described in the first embodiment.
- the radio base station BS2 has a normalization unit 332 having the same function as the normalization unit 132 described in the first embodiment.
- the normalization unit 332 has the same function as the normalization unit 132 described in the first embodiment.
- it is the same as that of 1st Embodiment.
- step S23 the propagation path information generation unit 131 of the radio terminal UE generates propagation path information 1 and propagation path information 2. Then, the transmitter 122 of the radio terminal UE omits the feedback of the propagation path information 1 to the radio base station BS1, and transmits the propagation path information 1 and the propagation path information 2 generated by the propagation path information generation section 131 to the radio base station. Feedback to station BS2. The receiving unit 321 of the radio base station BS2 receives the fed back propagation path information 1 and propagation path information 2.
- step S24 the normalization unit 332 of the radio base station BS2 normalizes the propagation path information 2 based on the propagation path information 1 by the same process as that described in (2) normalization process in the first embodiment. To do.
- the weight control unit 331 of the radio base station BS2 notifies the transmission unit 322 of the transmission antenna weight 2 corresponding to the propagation path information 2 normalized by the normalization unit 332.
- step S25 the transmission unit 322 of the radio base station BS2 weights (precodes) the transmission signal using the transmission antenna weight 2 notified from the weight control unit 331, and receives the radio signal RS2 including the weighted transmission signal. Send.
- the transmission unit 222 of the radio base station BS1 constantly transmits the radio signal RS1 including the transmission signal using one transmission antenna.
- the radio terminal UE when the radio base station BS1 transmits the radio signal RS1 using one transmission antenna, the radio terminal UE omits feedback to the radio base station BS1.
- the propagation path information 1 and the propagation path information 2 are fed back to the radio base station BS2, and the radio base station BS2 uses the propagation path information 1 fed back from the radio terminal UE as a reference and the propagation path fed back from the radio terminal UE.
- the information 2 is normalized, and the radio signal RS2 is transmitted according to the normalized propagation path information 2.
- the radio terminal UE since the radio terminal UE only needs to set a control channel for feedback with the radio base station BS2, consumption of radio resources in the uplink is reduced. Further, since the radio base station BS2 transmits the radio signal RS2 according to the propagation path information 2 in which the relative relationship with the propagation path information 1 is maintained, feedback to the radio base station BS1 is omitted. In addition, the inter-base station cooperative MIMO communication can function normally.
- the radio base station BS1 has a plurality of antennas 211. However, when the radio base station BS1 originally has only one antenna 211, an antenna selection process (see FIG. 7). Step S12 and step S22 in FIG. 10 are not necessary.
- the feedback channel information is a channel estimation value, a transmission antenna weight, or an index thereof.
- the present invention is not limited to this, and a future channel is calculated based on the channel estimation value. It may be a predicted channel value indicating the characteristic.
- the propagation path information 1 and the propagation path information 2 are fed back to the radio base station BS2, the propagation path information 1 and the propagation path information 2 are transferred from the radio base station BS2 to the radio base station BS1. It is also possible to switch the radio base station having one transmission antenna from the radio base station BS1 to the radio base station BS2 after transfer.
- the radio terminal As described above, according to the radio communication system, the radio terminal, the radio base station, and the radio communication method according to the present invention, it is possible to reduce overhead caused by feedback while normally functioning cooperative MIMO communication between base stations, and to reduce mobility. This is useful in wireless communication such as body communication.
Abstract
Description
第1実施形態においては、(1)無線通信システムの構成、(2)正規化処理、(3)基地局選択処理、(4)アンテナ選択処理、(5)無線通信システムの動作、(6)第1実施形態の効果について説明する。
まず、(1.1)全体概略構成、(1.2)無線端末UEの構成、(1.3)無線基地局BS1の構成、(1.4)無線基地局BS2の構成について説明する。
図1は、基地局間協調MIMO通信(マルチセル協調送受信又は複数地点協調送受信(CoMP))が導入された無線通信システム1の概略構成図である。
図2は、無線端末UEの構成を示すブロック図である。
図3は、無線基地局BS1の構成を示すブロック図である。
図4は、無線基地局BS2の構成を示すブロック図である。
次に、図5及び図6を参照して、正規化部132によって実行される正規化処理について説明する。まず、伝播路情報1が伝搬路推定値1であり、伝播路情報2が伝搬路推定値2である場合について説明する。
次に、フィードバックが省略される無線基地局(無線基地局BS1)を選択する処理である基地局選択処理について説明する。基地局選択処理は、無線端末UE、無線基地局BS1、無線基地局BS2、及び制御装置11の何れが実行してもよい。
選択方法1においては、無線端末UEから遠くに位置する無線基地局を無線基地局BS1として選択し、無線端末UEから近くに位置する無線基地局を無線基地局BS2として選択する。これにより、無線端末UEは、無線端末UEから近くに位置する無線基地局BS2へのフィードバックを行い、無線端末UEから遠くに位置する無線基地局BS1へのフィードバックを省略することになり、フィードバック用の送信電力を低減でき、与干渉量を低減できる。無線端末UEの電池残量が少ない場合等には選択方法1が好ましい。なお、選択方法1においては、無線端末UEと無線基地局BS1との間の距離、及び無線端末UEと無線基地局BS2との間の距離の情報が必要となるが、無線端末UEに設けられるGPS等を利用して距離の情報を得ることができる。
選択方法2においては、処理性能が高い無線基地局(具体的には、マクロセル基地局)を無線基地局BS1として選択し、処理性能が低い無線基地局(具体的には、フェムトセル基地局)を無線基地局BS2として選択する。通常、フェムトセル基地局は、無線端末UEの近くに存在するため、無線端末UEは、無線端末UEから近くに位置する無線基地局BS2へのフィードバックを行い、無線端末UEから遠くに位置する無線基地局BS1へのフィードバックを省略することができる。例えば無線端末UEにGPS等が設けられていない場合には、選択方法2が有効である。
選択方法3においては、処理性能が低い無線基地局(具体的には、フェムトセル基地局)を無線基地局BS1として選択し、処理性能が高い無線基地局(具体的には、マクロセル基地局)を無線基地局BS2として選択する。処理性能が低い無線基地局に1本アンテナの一定送信を実行させ、処理性能が高い無線基地局にマルチアンテナのマルチストリーム送信をさせることで、高速な伝送速度を得ることができるため、選択方法3は、高速な伝送速度が要求される場合や、無線端末UEの電池残量が多い場合に有効である。
選択方法4においては、無線端末UEとの間の伝搬路変動が小さい無線基地局を無線基地局BS1として選択し、無線端末UEとの間の伝搬路変動が大きい無線基地局を無線基地局BS2として選択する。これは、無線基地局BS1は1本アンテナの一定送信となるため、伝搬路変動が小さいことが好ましいからである。各無線基地局との間の伝搬路変動に大きな差がある場合には、選択方法4が有効である。
選択方法5においては、無線端末UEとの間の伝搬路損失が大きい無線基地局を無線基地局BS1として選択し、無線端末UEとの間の伝搬路損失が小さい無線基地局を無線基地局BS2として選択する。伝搬路損失は、無線基地局における送信電力と、無線端末UEにおける受信電力との差として計算され、端末・基地局間の距離を反映している。このため、無線端末UEは、無線端末UEから近くに位置する無線基地局BS2へのフィードバックを行い、無線端末UEから遠くに位置する無線基地局BS1へのフィードバックを省略することができる。伝搬路損失は、送信電力制御等の他の用途に使用され、容易に得ることができるため、選択方法5によれば既存のシステム構成を有効に活用できる。
次に、無線基地局BS1の複数のアンテナ211の中から、無線信号RS1の送信に用いる1本の送信アンテナを選択する処理であるアンテナ選択処理について説明する。
次に、図7を参照して、第1実施形態に係る無線通信システム1の動作について説明する。
無線基地局BS1が送信アンテナを1本用いて無線信号RS1を送信する場合、無線端末UEは、無線基地局BS1へのフィードバックを省略する。これにより、フィードバックに伴うオーバヘッドを低減できる。すなわち、無線端末UEが無線基地局BS2との間にのみフィードバック用の制御チャネルを設定すればよいため、アップリンクにおける無線リソースの消費量が削減される。
第1実施形態においては無線端末UEが伝搬路情報の正規化を行っていたが、第2実施形態では、無線基地局BS2が伝搬路情報の正規化を行う。以下において、(1)無線通信システムの構成、(2)無線通信システムの動作、(3)第2実施形態の効果について説明する。ただし、第1実施形態と異なる点を説明する。
図8は、第2実施形態に係る無線端末UEの構成を示すブロック図である。図9は、第2実施形態に係る無線基地局BS2の構成を示すブロック図である。
次に、図10を参照して、第2実施形態に係る無線通信システム1の動作について説明する。ただし、ステップS21及びS22の処理は第1実施形態と同様であるため、ステップS23以降の処理について説明する。
第2実施形態では、無線基地局BS1が送信アンテナを1本用いて無線信号RS1を送信する場合、無線端末UEは、無線基地局BS1へのフィードバックを省略するとともに、伝播路情報1及び伝播路情報2を無線基地局BS2にフィードバックし、無線基地局BS2は、無線端末UEからフィードバックされた伝播路情報1を基準として、無線端末UEからフィードバックされた伝播路情報2を正規化し、正規化された伝播路情報2に応じて無線信号RS2を送信する。
上記のように、本発明は実施形態によって記載したが、この開示の一部をなす論述及び図面はこの発明を限定するものであると理解すべきではない。この開示から当業者には様々な代替実施形態、実施例及び運用技術が明らかとなる。
Claims (17)
- 無線端末と、
前記無線端末からのフィードバックに応じて第1無線信号を前記無線端末に送信する第1無線基地局と、
前記無線端末からのフィードバックに応じて、前記第1無線信号と同一の周波数及び同一の時間で第2無線信号を前記無線端末に送信する第2無線基地局と
を有し、
前記第1無線基地局において前記第1無線信号の送信に用いる送信アンテナが1本である場合、前記無線端末は、前記第1無線基地局へのフィードバックを省略する無線通信システム。 - 前記送信アンテナが1本である場合、前記無線端末は、前記第1無線基地局へのフィードバックを省略するとともに、前記第1無線基地局から前記無線端末までの伝搬路特性に応じた第1伝搬路情報と、前記第2無線基地局から前記無線端末までの伝搬路特性に応じた第2伝搬路情報とに基づくフィードバックを前記第2無線基地局に対して行う請求項1に記載の無線通信システム。
- 前記送信アンテナが1本である場合、前記無線端末は、前記第1無線基地局へのフィードバックを省略するとともに、前記第1伝搬路情報を基準として前記第2伝搬路情報を正規化し、前記正規化された第2伝搬路情報を前記第2無線基地局にフィードバックする請求項2に記載の無線通信システム。
- 前記送信アンテナが1本である場合、前記無線端末は、前記第1無線基地局へのフィードバックを省略するとともに、前記第1伝搬路情報及び前記第2伝搬路情報を前記第2無線基地局にフィードバックし、
前記第2無線基地局は、前記無線端末からフィードバックされた前記第1伝搬路情報を基準として、前記無線端末からフィードバックされた前記第2伝搬路情報を正規化し、前記正規化された第2伝搬路情報に応じて前記第2無線信号を送信する請求項2に記載の無線通信システム。 - 前記第1伝搬路情報は、前記第1無線基地局の送信アンテナと前記無線端末の受信アンテナとの間の伝搬路特性を示す情報であり、
前記第2伝搬路情報は、前記第2無線基地局の送信アンテナと前記無線端末の受信アンテナとの間の伝搬路特性を示す情報である請求項2に記載の無線通信システム。 - 前記第1伝搬路情報は、前記第1無線信号の位相又は振幅の少なくとも一方の制御に用いられる第1送信アンテナウェイト、又は、前記第1送信アンテナウェイトを示すインデックスであり、
前記第2伝搬路情報は、前記第2無線信号の位相又は振幅の少なくとも一方の制御に用いられる第2送信アンテナウェイト、又は、前記第2送信アンテナウェイトを示すインデックスである請求項2に記載の無線通信システム。 - 前記無線端末は、前記第1無線信号の受信品質又は伝搬路特性を前記第1無線基地局の送信アンテナ毎に測定し、
前記第1無線基地局は、前記測定された受信品質又は前記測定された伝搬路特性に応じて選択される1本の前記送信アンテナを用いて、前記第1無線信号を前記無線端末に送信する請求項1に記載の無線通信システム。 - 前記無線端末からのフィードバックが省略される前記第1無線基地局は、前記第2無線基地局よりも、前記無線端末から遠くに位置する無線基地局である請求項1に記載の無線通信システム。
- 前記無線端末からのフィードバックが省略される前記第1無線基地局は、前記第2無線基地局よりも処理性能が高い無線基地局である請求項1に記載の無線通信システム。
- 前記無線端末からのフィードバックが省略される前記第1無線基地局は、前記第2無線基地局よりも処理性能が低い無線基地局である請求項1に記載の無線通信システム。
- 前記無線端末からのフィードバックが省略される前記第1無線基地局は、前記第2無線基地局よりも、前記無線端末との間の伝搬路変動が小さい無線基地局である請求項1に記載の無線通信システム。
- 前記無線端末からのフィードバックが省略される前記第1無線基地局は、前記第2無線基地局よりも、前記無線端末との間の伝搬路損失が大きい無線基地局である請求項1に記載の無線通信システム。
- 第1無線基地局から第1無線信号を受信し、前記第1無線信号と同一の周波数及び同一の時間で第2無線信号を第2無線基地局から受信する受信部と、
前記第1無線基地局及び前記第2無線基地局へのフィードバックを送信する送信部と
を有し、
前記第1無線基地局において前記第1無線信号の送信に用いる送信アンテナが1本である場合、前記送信部は、前記第1無線基地局へのフィードバックを省略する無線端末。 - 無線端末からのフィードバックに応じて第1無線信号を前記無線端末に送信する第1無線基地局と、
前記無線端末からのフィードバックに応じて、前記第1無線信号と同一の周波数及び同一の時間で第2無線信号を前記無線端末に送信する第2無線基地局と
を有し、
前記第1無線基地局において前記第1無線信号の送信に用いる送信アンテナが1本である場合、前記第1無線基地局又は前記第2無線基地局は、前記第1無線基地局へのフィードバックを省略するよう前記無線端末に指示する無線通信システム。 - 基地局間協調通信が実行されているとき、所定の無線基地局に対するフィードバックを省略するよう無線端末に指示する指示部を備える無線基地局。
- 前記所定の無線基地局は、前記所定の無線基地局以外の他の無線基地局よりも前記無線端末から遠くに位置する無線基地局、前記他の無線基地局よりも処理性能が高い無線基地局、前記他の無線基地局よりも処理性能が低い無線基地局、前記他の無線基地局よりも前記無線端末との間の伝搬路変動が小さい無線基地局、又は、前記他の無線基地局よりも前記無線端末との間の伝搬路損失が大きい無線基地局である請求項15に記載の無線基地局。
- 無線端末からのフィードバックに応じて第1無線基地局が第1無線信号を前記無線端末に送信するステップと、
前記無線端末からのフィードバックに応じて、前記第1無線信号と同一の周波数及び同一の時間で第2無線基地局が第2無線信号を前記無線端末に送信するステップと、
前記第1無線基地局において前記第1無線信号の送信に用いる送信アンテナが1本である場合、前記無線端末が、前記第1無線基地局へのフィードバックを省略するステップと
を有する無線通信方法。
Priority Applications (3)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US13/321,976 US8768266B2 (en) | 2009-05-27 | 2010-05-27 | Radio communication system, radio terminal, radio base station and radio communication method |
EP10780619A EP2437534A1 (en) | 2009-05-27 | 2010-05-27 | Wireless communication system, wireless terminal, wireless base station, and wireless communication method |
CN201080023648.0A CN102450048A (zh) | 2009-05-27 | 2010-05-27 | 无线通信系统、无线终端、无线基站和无线通信方法 |
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JP (1) | JP5315130B2 (ja) |
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CN107436602A (zh) * | 2017-07-05 | 2017-12-05 | 深圳大学 | 基于单比特反馈的移动设备的位置控制方法及装置 |
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EP2897302B1 (en) | 2012-10-10 | 2018-04-04 | Huawei Technologies Co., Ltd. | Method for communication through distributed antenna array system and array system |
US8989125B1 (en) * | 2013-03-13 | 2015-03-24 | Sprint Spectrum L.P. | Adaptive CoMP schemes in LTE networks based on battery life |
CN103402217B (zh) * | 2013-07-29 | 2016-07-13 | 长沙威佳通信科技有限公司 | 基站天线参数处理系统 |
JP7175091B2 (ja) * | 2018-03-13 | 2022-11-18 | 株式会社日立国際電気 | 無線通信システム、送信局及び受信局 |
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JP2010045783A (ja) * | 2008-08-11 | 2010-02-25 | Ntt Docomo Inc | マルチセル協調送信方法 |
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CN107436602A (zh) * | 2017-07-05 | 2017-12-05 | 深圳大学 | 基于单比特反馈的移动设备的位置控制方法及装置 |
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KR20120016641A (ko) | 2012-02-24 |
JP2010278672A (ja) | 2010-12-09 |
JP5315130B2 (ja) | 2013-10-16 |
US8768266B2 (en) | 2014-07-01 |
US20120142395A1 (en) | 2012-06-07 |
CN102450048A (zh) | 2012-05-09 |
EP2437534A1 (en) | 2012-04-04 |
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