WO2012102483A1 - 다중 노드 시스템에서 채널 상태 정보 피드백 방법 및 장치 - Google Patents
다중 노드 시스템에서 채널 상태 정보 피드백 방법 및 장치 Download PDFInfo
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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
- H04B7/022—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
- H04B7/04—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas
- H04B7/0413—MIMO systems
- H04B7/0456—Selection of precoding matrices or codebooks, e.g. using matrices antenna weighting
- H04B7/0478—Special codebook structures directed to feedback optimisation
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B7/00—Radio transmission systems, i.e. using radiation field
- H04B7/02—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas
- H04B7/04—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas
- H04B7/06—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
- H04B7/066—Combined feedback for a number of channels, e.g. over several subcarriers like in orthogonal frequency division multiplexing [OFDM]
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L25/00—Baseband systems
- H04L25/02—Details ; arrangements for supplying electrical power along data transmission lines
- H04L25/03—Shaping networks in transmitter or receiver, e.g. adaptive shaping networks
- H04L25/03891—Spatial equalizers
- H04L25/03898—Spatial equalizers codebook-based design
- H04L25/03904—Spatial equalizers codebook-based design cooperative design, e.g. exchanging of codebook information between base stations
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L5/00—Arrangements affording multiple use of the transmission path
- H04L5/003—Arrangements for allocating sub-channels of the transmission path
- H04L5/0032—Distributed allocation, i.e. involving a plurality of allocating devices, each making partial allocation
- H04L5/0035—Resource allocation in a cooperative multipoint environment
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L5/00—Arrangements affording multiple use of the transmission path
- H04L5/0091—Signaling for the administration of the divided path
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B7/00—Radio transmission systems, i.e. using radiation field
- H04B7/02—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas
- H04B7/04—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas
- H04B7/06—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the transmitting station
- H04B7/0613—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the transmitting station using simultaneous transmission
- H04B7/0615—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the transmitting station using simultaneous transmission of weighted versions of same signal
- H04B7/0619—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the transmitting station using simultaneous transmission of weighted versions of same signal using feedback from receiving side
- H04B7/0636—Feedback format
- H04B7/0639—Using selective indices, e.g. of a codebook, e.g. pre-distortion matrix index [PMI] or for beam selection
Definitions
- the present invention relates to wireless communications, and more particularly, to a method and apparatus for feeding back channel state information in a multi-node system.
- the node may mean an antenna or a group of antennas separated by a predetermined interval from a distributed antenna system (DAS), but may be used in a broader sense without being limited to this meaning. That is, the node may be a macro base station, a picocell base station (PeNB), a home base station (HeNB), a remote radio head (RRH), a remote radio unit (RRU), a repeater, a distributed antenna (group), or the like.
- DAS distributed antenna system
- the node may be a macro base station, a picocell base station (PeNB), a home base station (HeNB), a remote radio head (RRH), a remote radio unit (RRU), a repeater, a distributed antenna (group), or the like.
- Wireless communication systems with high density nodes can exhibit higher system performance by cooperation between nodes.
- each node operates as an antenna or a group of antennas for one cell by receiving and receiving transmission and reception by one control station, each system can perform much better system performance than when each node operates as an independent base station without cooperating with each other.
- a wireless communication system including a plurality of nodes is called a multi-node system.
- Coordinated multiple point transmission and reception (CoMP) between each node may be applied to such a multi-node system.
- the cooperative transmission refers to a transmission method in which a plurality of nodes participate in signal transmission and reception for the same terminal.
- Cooperative transmission techniques include a joint processing technique and a scheduling coordination technique.
- the joint processing technique is a technique in which a plurality of nodes participate in signal transmission and reception simultaneously, such as joint transmission (JT) and dynamic cell selection (DCS).
- Scheduling cooperation scheme is a technique in which a plurality of nodes participate in signal transmission and reception for the same terminal at different times by scheduling, such as coordinated scheduling (CS), coordinated beamforming (CB).
- CS coordinated scheduling
- CB coordinated beamforming
- a channel state information feedback method of a terminal in a multi-node system including a plurality of nodes and a base station that can be connected to and control each of the plurality of nodes.
- the method includes the steps of obtaining one precoding matrix index (PMI) for each cooperating node for the entire target frequency band; Obtaining a phase correction value to be applied to the PMI for each cooperative node in each of the subbands in the target frequency band; And feeding back the obtained PMI and phase correction values to the serving node.
- PMI precoding matrix index
- the target frequency band may be the entire system band of the multi-node system.
- the phase correction value to be applied to the PMI for each cooperative node may be information used to connect PMIs for two or more different cooperative nodes to form a single precoding matrix.
- the method may further comprise receiving target frequency band information from a serving node, wherein the target frequency band information may indicate the target frequency band.
- the target frequency band information may indicate some frequency bands of all system bands as the target frequency band.
- the phase correction value to be applied to the PMI for each cooperative node may be N or less. Where N is a natural number of 2 or more.
- a difference value between a time of receiving a signal transmitted from a reference node which is one of the plurality of nodes and a time of receiving a signal of each of the cooperative nodes is obtained. You can feedback.
- the difference value may be given as an index corresponding to each of a plurality of predetermined time intervals.
- the method may further comprise receiving a reference signal from a serving node and each of the cooperating nodes.
- One PMI and phase correction value for each cooperative node may be obtained by measuring the reference signal.
- the RF unit for transmitting and receiving radio signals; And a processor coupled to the RF unit, wherein the processor obtains one precoding matrix index (PMI) for each cooperative node for the entire target frequency band, and each of the subbands in the target frequency band. Obtains a phase correction value to be applied to the PMI for each cooperative node, and feeds back the obtained PMI and phase correction value to the serving node.
- PMI precoding matrix index
- the amount of channel state information fed back by the terminal can be reduced. Therefore, the feedback overhead of the terminal can be reduced.
- FIG. 1 shows an example of a multi-node system.
- FIG. 2 shows an example of a multi-node system configuration.
- FIG 3 shows another example of a multi-node system configuration.
- FIG. 4 illustrates a channel state information feedback method according to an embodiment of the present invention.
- 5 shows an effective channel between a terminal and each node.
- FIG. 6 is a block diagram of a base station and a terminal in which an embodiment of the present invention is implemented.
- CDMA code division multiple access
- FDMA frequency division multiple access
- TDMA time division multiple access
- OFDMA orthogonal frequency division multiple access
- SC-FDMA single carrier-frequency division multiple access
- CDMA may be implemented with a radio technology such as Universal Terrestrial Radio Access (UTRA) or CDMA2000.
- TDMA may be implemented with wireless technologies such as Global System for Mobile communications (GSM) / General Packet Radio Service (GPRS) / Enhanced Data Rates for GSM Evolution (EDGE).
- GSM Global System for Mobile communications
- GPRS General Packet Radio Service
- EDGE Enhanced Data Rates for GSM Evolution
- OFDMA may be implemented in a wireless technology such as Institute of Electrical and Electronics Engineers (IEEE) 802.11 (Wi-Fi), IEEE 802.16 (WiMAX), IEEE 802.20, Evolved UTRA (E-UTRA).
- UTRA is part of the Universal Mobile Telecommunications System (UMTS).
- 3rd Generation Partnership Project (3GPP) Long Term Evolution (LTE) is a part of Evolved UMTS (E-UMTS) using E-UTRA, and employs OFDMA in downlink and SC-FDMA in uplink.
- LTE-A Advanced
- IEEE 802.16m is the successor to IEEE 802.16e.
- FIG. 1 shows an example of a multi-node system.
- the multi-node system includes a base station (BS) and a plurality of nodes.
- BS base station
- a base station generally refers to a fixed station communicating with a terminal, and may be referred to as other terms such as an evolved-NodeB (eNB), a base transceiver system (BTS), and an advanced base station (ABS).
- eNB evolved-NodeB
- BTS base transceiver system
- ABS advanced base station
- a node may be referred to as an antenna node (AN).
- the node is not limited to a distributed antenna and may be implemented with, for example, a macro base station, a picocell base station (PeNB), a home base station (HeNB), a remote radio head (RRH), a repeater, and the like.
- Nodes are also called points. These nodes may be wired or wirelessly connected to the base station and controlled / managed by the base station.
- the node may be identified or indicated through a reference signal (RS) or a pilot signal from the viewpoint of the terminal.
- the reference signal (or pilot signal, hereinafter identical) refers to a signal used by a transmitter and a receiver to be used for channel measurement and data demodulation.
- Examples of reference signals include a CSI-RS (channel status indication-reference signal) defined in 3GPP LTE-A, a preamble defined in IEEE 802.16m, a midamble, and the like.
- CSI-RS channel status indication-reference signal
- Such a reference signal or configuration of the reference signal may be mapped to each node (or a transmission antenna of each node).
- the terminal may identify or be instructed on the basis of the CSI-RS configuration, and may obtain channel state information on the node.
- the reference signal configuration may include information about a configuration index, the number of antenna ports of each node, a resource element used (RE), a transmission period, and an offset of a transmission time point. Therefore, for convenience of description, the description that the terminal measures a signal or generates channel state information for a specific node may mean that the terminal measures a signal for a specific reference signal or generates channel state information.
- a node is connected to a base station via a wired / wireless network, and each node may be configured of one antenna or a plurality of antennas (ie, an antenna group). Antennas belonging to one node may be located within a few meters geographically and have the same characteristics. In a multi-node system, a node serves as an access point (AP) to which a terminal can access.
- AP access point
- a distributed antenna system refers to a system in which antennas (ie, nodes) are distributed in geographically diverse locations and managed by the base station.
- the distributed antenna system is different from that in the conventional centralized antenna system (CAS), antennas of a base station are concentrated and arranged in a cell center.
- CAS conventional centralized antenna system
- the geographically distributed antennas may mean that when one receiver receives the same signal from a plurality of antennas, a channel state difference between each antenna and the receiver is arranged to be different by a specific value or more. have. Meaning that the antennas are concentrated may mean that the antennas are densely arranged such that the channel state difference between each antenna and one receiver is less than a specific value.
- the specific value may be variously determined according to a frequency, a service type, etc. used for the antennas.
- FIG. 2 shows an example of a multi-node system configuration.
- a plurality of nodes may be arranged in a macro cell in which a base station provides a service. That is, the multi-node system may be in the form of a heterogeneous network in which a plurality of nodes having low transmit power are included in macro cell coverage having high transmit power.
- each node may have a different cell ID from the macro cell (that is, the base station) or may have the same cell ID.
- the base station When each node has the same cell ID as the base station, it may be referred to as a single cell multi-node system.
- the cell ID may be used as a seed number when transmitting a synchronization signal or a reference signal, and the terminal may identify the cell ID of each node through the synchronization signal or the reference signal.
- FIG 3 shows another example of a multi-node system configuration.
- a multi-node system may assign a cell ID common to each node and transmit a signal generated by all nodes using the same cell ID.
- each node may be implemented as a virtual cell.
- the virtual cell refers to a device that is not recognized as an independent cell or antenna (port) to a legacy terminal, but can be recognized as an independent cell or antenna (port) to an advanced terminal.
- each node 610 through 615 in the multi-node system may generate and transmit essential information using the cell common ID.
- the essential information may be system information, inter-cell movement, that is, information related to cell selection / reselection or handover.
- both the legacy terminal and the improved terminal can receive essential information as in the conventional method, and the legacy terminal recognizes each node as the same cell.
- the same cell recognized by the legacy terminal is called a mother cell.
- the improved terminal can also recognize the mother cell.
- each node 610 through 615 in the multi-node system may have a dedicated cell ID separately from the cell common ID.
- the dedicated cell ID may be a value generated independently of the cell common ID or a value generated by setting a specific relationship with the cell common ID.
- Each node 610 to 615 may generate / transmit a signal transmitted through a channel other than a channel through which a pilot signal or essential information is transmitted using the dedicated cell ID. This signal can only be recognized by the improved terminal.
- the cell that only the improved terminal can recognize is a virtual cell. Virtual cells may be recognized as cooperative cells in cooperative transmission for an improved terminal.
- a multi-node system in which a node is implemented as a virtual cell is called a virtual cell system.
- cooperative transmission may be performed to reduce interference or improve system performance between each virtual cell, or between a mother cell and a virtual cell.
- Cooperative transmission generally requires feedback of channel state information of the terminal.
- the channel state information fed back may be classified into explicit information indicating a pure channel state without assuming a specific precoding process and implicit information indicating a channel state with a specific precoding process.
- Explicit information includes a channel matrix, channel covariance, and the like, and implicit information includes a precoding matrix index (PMI), a channel quality indicator (CQI), and a rank indicator (RI).
- the terminal may transmit a sounding signal instead of the channel state information feedback.
- the base station can measure the channel state through the sounding signal.
- Joint transmission is a cooperative transmission technique in which a plurality of nodes transmit a signal to the same terminal in the same time / frequency resource.
- IEEE 802.11m supports closed-loop macro diversity (CL-MD) and collaborative MIMO (Co-MIMO) of multiple base station MIMO. These two modes may be referred to as joint transmission.
- the UE feeds back a PMI for each node, a concatenating PMI (CPMI) for connecting the PMI, and a CQI.
- CPMI is information used to connect two or more different precoding matrices into one precoding matrix.
- Each precoding matrix in the codebook is configured such that the phase of the coefficient corresponding to the first antenna is zero (ie, only real components exist). Therefore, in order to connect two or more different precoding matrices, it is necessary to correct the phase difference of the first components of each precoding matrix.
- a base station indicates a specific band to a terminal, and the terminal feeds back one PMI and one CPMI for each cooperative base station with respect to the specific band.
- one PMI, CPMI is for the entire specific band.
- the gain by the cooperative transmission may increase.
- the reason for feeding back the PMI and the CPMI for the entire specific band is that the feedback information amount increases during the PMI and CPMI feedback for each subband, and the performance improvement is not large compared to the increasing feedback information amount.
- the reason why the performance improvement is not so large is that the conventional cooperative transmission first considers cooperation between base stations, and as a result, the time difference between the time when the terminal measures the channel and the time when the base station receives the feedback from the terminal and performs the actual cooperative transmission is increased. This is because the channel environment changes in between, and the accuracy of the measured channel decreases.
- the backhaul latency between nodes is very short. Therefore, in the multi-node system, instead of feeding back the entire PMI and the CPMI for the specific band indicated by the base station, feeding back the PMI and CPMI for each subband of the specific band may increase the system efficiency. For example, by dividing a specific band into M subbands and feeding back N (N is less than or equal to M) PMIs and N CPMIs for each cooperative base station, system efficiency may be increased.
- the UE may transmit PMI and CPMI only for subbands having a quality greater than or equal to a certain threshold, or may transmit PMI and CPMI only for a specific number of subbands predefined by a base station. If N is large enough, there is almost no performance difference from feeding back PMI and CPMI for all subbands.
- the present invention proposes a method for transmitting PMI and CPMI while reducing feedback overhead while showing a system performance similar to the case of sending PMI and CPMI for each subband.
- FIG. 4 illustrates a channel state information feedback method according to an embodiment of the present invention.
- the serving node designates a target frequency band to the terminal (S101).
- the serving node may be a macro base station, but is not limited thereto.
- the following table shows an example of information indicating a target frequency band in IEEE 802.16m.
- Control channel IE control channel Information element
- ICT Interference cooperation type Interference coordination type
- PMI limit 0b01: PMI recommended
- CL-MD 0b11: Co-MIMO Feedback Polling
- A-MAP IE Multiple base station MIMO mode indication
- Target resource unit Target resource unit 0b00: latest best subbands reported for single BS MIMO 0b01: whole bandwidth 0b10: FFR partition 0 0b11: boosted FFR partition 0
- 'TRU' indicates a target resource unit that is a target of channel state information feedback.
- the target frequency band of the target resource unit may be variously set, such as a whole bandwidth, an FFR partition 0, a boosted FFR partition, and the like.
- the serving node and the cooperating node transmit a reference signal to the terminal (S102-1, S102-2).
- the UE measures the reference signal to obtain one PMI per cooperative node or reference signal for the target frequency band (S102).
- one PMI obtained for each cooperative node or reference signal may be a PMI for the entire target frequency band.
- the one PMI may be a representative value among PMIs obtained for subbands obtained by dividing a target frequency band.
- the target frequency band may be given as F1
- the target frequency band F1 may be divided into three subbands such as f1, f2, and f3.
- the PMI for each of the three subbands is obtained, and one PMI can be used as the representative value. The reason why one PMI may be obtained per cooperative node with respect to the target frequency band will be described later.
- the UE obtains N CPMIs for each cooperative node for each subband in the target frequency band (S103).
- N may be the total number of subbands in the target frequency band. Or N may be less than the total number of subbands in the target frequency band.
- the CPMI is transmitted to only N subbands selected by the UE among all subbands in the target frequency band, or the base station designates N subbands to which the CPMI is fed back among all subbands in the target frequency band to the UE. Can give
- the entire subbands in the target frequency band may be grouped into N subband groups to feed back CPMI for each subband group.
- the subband group may be composed of adjacent P subbands, where P is fixed to a specific value, a value is defined according to the system bandwidth, or the base station is assigned to the terminal as physical layer or higher layer control information. I can tell you.
- the terminal feeds back one PMI and N CPMIs for each cooperative node obtained in the above process to the serving node (S104).
- the method described with reference to FIG. 4 may be applied when the cooperative node is a node having a low transmission power, for example, a low power RRH, a picocell / femtocell base station.
- a low transmission power for example, a low power RRH, a picocell / femtocell base station.
- the node having the low transmission power is a cooperative node
- the distance between the terminal and the cooperative node is likely to be close.
- the channel environment is likely to be a line of sight (LoS). In the LoS environment, there are few scattering factors, and there is a high probability that the delay spread is not large. Therefore, the channel between the cooperating node and the terminal has a high frequency flat characteristic.
- LoS line of sight
- the terminal feeds back only one PMI for the entire target frequency band for each cooperative node. As a result, the feedback overhead of the terminal is reduced.
- CPMI does not appear uniformly over the target frequency band. This is because a difference may occur in the arrival time of a signal transmitted from each cooperating node. Therefore, a phase difference may appear for each frequency between channels between the cooperative nodes and the terminal. This is the same principle that frequency selectivity is caused by multiple paths.
- the serving node is a macro base station having a high transmission power, it may not be a LoS environment between the macro base station and the terminal. Accordingly, the UE feeds back N CPMIs for the N subbands.
- the serving node designates the target frequency band to the terminal through step S101
- this process may be omitted.
- the target frequency band of the terminal may be the entire system band.
- the terminal obtains one PMI for each cooperating node for the entire system band in step S103, and configures N CPMIs for each cooperating node for each subband in the whole system band in step S104.
- N CPMIs are calculated for each cooperative node for each subband in the target frequency band, but this is not a limitation.
- the UE may feed back a parameter for obtaining the CPMI instead of the CPMI. This method is particularly useful in an environment where all nodes (reference node and cooperating node) are LoS. This is explained.
- the terminal performs synchronization with one node among all nodes participating in the cooperative transmission.
- the target node to which the terminal performs synchronization is called a reference node.
- the reference node is node # 1.
- the signal transmitted by node # 1 reaches the terminal at time t 1 .
- a signal transmitted by the i-th node (node #i) which is a cooperative node participating in joint transmission, reaches the terminal at time t i .
- ATD arrival time difference
- 5 shows an effective channel between a terminal and each node.
- a channel between node # 1, which is a reference node, and a terminal is H 1 (f)
- a channel between node #i (i is a natural number of 2 or more), which is a cooperative node, and e j2 ⁇ fdi H i (f) ( Or e -j2 ⁇ fdi H i (f)).
- channel H i (f) of the cooperative nodes is in the form of c i (c i is an arbitrary constant)
- the effective channel of the cooperative nodes based on the reference node may be represented by c i e j2 ⁇ fdi . That is, it can be referred to as a channel having a fixed size and whose phase changes constantly according to the frequency f.
- the CPMI value has a high probability of being determined with a certain difference for each subband in the target frequency band.
- the difference between the CPMI values (phase correction values) of the n-1th subband and the nth subband may be equal to the difference between the CPMI values (phase correction value) of the nth subband and the n + 1th subband.
- the precoding matrix applied to the i-th cooperative node becomes e j2 ⁇ i W i .
- the serving node may perform phase correction.
- the UE may feed back a parameter, for example, one ATD, that may generate CPMI instead of N CPMIs per cooperative node for subbands within a target frequency band. That is, the UE may feed back only one ATD, instead of feeding back N CPMIs. In this way, feedback overhead of the UE can be reduced.
- a parameter for example, one ATD, that may generate CPMI instead of N CPMIs per cooperative node for subbands within a target frequency band. That is, the UE may feed back only one ATD, instead of feeding back N CPMIs. In this way, feedback overhead of the UE can be reduced.
- the terminal may feed back an index indicative of a specific section instead of feeding back the ATD value itself. For example, if the value of ATD is greater than or equal to t1 and less than t2, index 1; i More than t i + 1 If less, the ATD may be fed back in the form of index like index i. Such an index may be referred to as an interval time difference index (ATDI).
- ATDI interval time difference index
- the ATD may be quantized by a specific reference sampling time unit to use the quantized value as ATDI.
- the phase correction value determined by CPMI may be modeled as e j ( ⁇ s + ⁇ ) .
- the terminal may feed back only the parameters ⁇ and ⁇ .
- s is an index indicating some bands in the target frequency band, and may be a subband index, a physical resource block (PRB) index, a tone (subcarrier or resource element) index, or the like.
- FIG. 6 is a block diagram of a base station and a terminal in which an embodiment of the present invention is implemented.
- the base station 800 includes a processor 810, a memory 820, and a radio frequency unit (RF) 830.
- the base station 800 may control a plurality of nodes in a multi-node system.
- Processor 810 implements the proposed functions, processes, and / or methods. Layers of the air interface protocol may be implemented by the processor 810.
- the processor 810 transmits information on a target frequency band and transmits a reference signal.
- the cooperative transmission is performed.
- the memory 820 is connected to the processor 810 and stores various information for driving the processor 810.
- the RF unit 830 is connected to the processor 810 to transmit and / or receive a radio signal.
- the terminal 900 includes a processor 910, a memory 920, and an RF unit 930.
- the RF unit 930 is connected to the processor 910 to transmit and / or receive a radio signal.
- Processor 910 implements the proposed functions, processes, and / or methods. That is, the processor 910 receives the target frequency band information from the base station, and after receiving the reference signal, obtains a PMI and a phase correction value for the target frequency band and feeds it back to the base station. Layers of the air interface protocol may be implemented by the processor 910.
- the memory 920 is connected to the processor 910 and stores various information for driving the processor 910.
- Processors 810 and 910 may include application-specific integrated circuits (ASICs), other chipsets, logic circuits, and / or data processing devices.
- the memory 820, 920 may include read-only memory (ROM), random access memory (RAM), flash memory, memory card, storage medium, and / or other storage device.
- the RF unit 830 and 930 may include a baseband circuit for processing a radio signal.
- the above-described technique may be implemented as a module (process, function, etc.) for performing the above-described function.
- the module may be stored in the memory 820, 920 and executed by the processor 810, 910.
- the memories 820 and 920 may be inside or outside the processors 810 and 910, and may be connected to the processors 810 and 910 by various well-known means.
- the methods are described based on a flowchart as a series of steps or blocks, but the invention is not limited to the order of steps, and certain steps may occur in a different order or concurrently with other steps than those described above. Can be.
- the steps shown in the flowcharts are not exclusive and that other steps may be included or one or more steps in the flowcharts may be deleted without affecting the scope of the present invention.
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Abstract
Description
파라미터 (parameter) |
기술 (description) |
값 (value) |
제어 채널 IE (control channel Information element) |
노트 (note) |
ICT | 간섭 협력 타입 (Interference coordination type) |
0b00: PMI 제한 0b01: PMI 추천 0b10:CL-MD 0b11:Co-MIMO |
피드백 폴링 A-MAP IE (Feedback Polling A-MAP IE) |
다중 기지국 MIMO 모드 지시 |
TRU | 타겟 자원 유닛 (Target resource unit) |
0b00: 단일 기지국 MIMO를 위해 리포트된 가장 최근의 베스트 서브밴드들(latest best subbands reported for single BS MIMO) 0b01: 전체 대역(whole bandwidth) 0b10:FFR 구획 0(FFR partition 0) 0b11:부스팅된 FFR 구획(boosted FFR partition 0) |
피드백 폴링 A-MAP IE (Feedback Polling A-MAP IE) |
피드백 측정을 위한 자원 유닛들을 지시 |
MaxUser | Co-MIMO에서 지원되는 최대 사용자 수 | 0b00: MaxUser =2 0b01: MaxUser =3 0b10: MaxUser =4 0b11: Reserved |
피드백 폴링 A-MAP IE (Feedback Polling A-MAP IE) |
Co-MIMO를 사용하는 다중 사용자 MIMO 전송에서 지원되는 최대 사용자 수 |
NIP_th_1 | 다중 기지국 협력 트리거와 함께하는 단일 기지국 프리코딩에 대한 NIP 문턱치(NIP threshold for Single BS precoding with multi-BS Coordination trigger) | 4 비트 | AAI-DL-IM | |
NIP_th_2 | 하향링크 다중 기지국 조인트 MIMO 처리 트리거링을 위한 NIP 문턱치(NIP threshold for DL Multi-BS Joint MIMO processing trigger) | 4 비트 | AAI-DL-IM | |
CINR_th | 다중 기지국 협력 및 다중 기지국 조인트 MIMO 처리 트리거와 함께하는 단일 기지국 프리코딩을 위한 CINR 문턱치 | 4 비트 | AAI-DL-IM | 단말에 의해 다중 기지국 MIMO 요청을 위해 NIP_th_1 또는 NIP_th_2와 함께 사용 |
Claims (20)
- 복수의 노드들과 상기 복수의 노드들 각각과 연결되어 제어할 수 있는 기지국을 포함하는 다중 노드 시스템에서 단말의 채널 상태 정보 피드백 방법에 있어서,
타겟 주파수 대역 전체에 대하여 각 협력 노드에 대한 하나씩의 프리코딩 행렬 인덱스(precoding matrix index : PMI)를 구하는 단계;
상기 타겟 주파수 대역 내의 서브 밴드 각각에서, 상기 각 협력 노드에 대한 PMI에 적용할 위상 보정 값을 구하는 단계; 및
상기 구해진 PMI 및 위상 보정 값을 상기 서빙 노드로 피드백하는 단계를 포함하는 것을 특징으로 하는 방법. - 제 1 항에 있어서, 상기 타겟 주파수 대역은 상기 다중 노드 시스템의 전체 시스템 대역인 것을 특징으로 하는 방법.
- 제 1 항에 있어서,
상기 각 협력 노드에 대한 PMI에 적용할 위상 보정 값은
서로 다른 2개 이상의 협력 노드에 대한 PMI들을 연결하여 하나의 프리코딩 행렬로 만드는데 사용되는 정보임을 특징으로 하는 방법. - 제 1 항에 있어서,
상기 서빙 노드로부터 타겟 주파수 대역 정보를 수신하는 단계를 더 포함하되, 상기 타겟 주파수 대역 정보는 상기 타겟 주파수 대역을 지시하는 것을 특징으로 하는 방법. - 제 4 항에 있어서, 상기 타겟 주파수 대역 정보는 전체 시스템 대역 중 일부 주파수 대역을 상기 타겟 주파수 대역으로 지시하는 것을 특징으로 하는 방법.
- 제 1 항에 있어서,
상기 타겟 주파수 대역 내의 서브 밴드의 개수가 N개인 경우, 상기 각 협력 노드에 대한 PMI에 적용할 위상 보정 값은 N개 이하인 것을 특징으로 하는 방법. 여기서, N은 2 이상의 자연수. - 제 1 항에 있어서,
상기 각 협력 노드에 대한 PMI에 적용할 위상 보정 값 대신
상기 복수의 노드 중 어느 하나인 기준 노드에서 전송한 신호를 수신한 시간과 상기 각 협력 노드가 전송한 신호를 수신한 시간의 차이값을 구하여 피드백하는 것을 특징으로 하는 방법. - 제 7 항에 있어서,
상기 차이값은 상기 타겟 주파수 대역에 대해 하나만 피드백하는 것을 특징으로 하는 방법. - 제 7 항에 있어서, 상기 차이값은 미리 정해진 복수의 시간 구간 각각 대응하는 인덱스로 주어지는 것을 특징으로 하는 방법.
- 제 1 항에 있어서, 상기 서빙 노드 및 상기 각 협력 노드로부터 참조 신호를 수신하는 단계를 더 포함하는 것을 특징으로 하는 방법.
- 제 10 항에 있어서, 상기 각 협력 노드에 대한 하나의 PMI 및 위상 보정 값은 상기 참조 신호를 측정하여 구하는 것을 특징으로 하는 방법.
- 무선신호를 송수신하는 RF부; 및
상기 RF부에 연결되는 프로세서를 포함하되, 상기 프로세서는
타겟 주파수 대역 전체에 대하여 각 협력 노드에 대한 하나의 프리코딩 행렬 인덱스(precoding matrix index : PMI)를 구하고, 상기 타겟 주파수 대역 내의 서브 밴드 각각에서 상기 각 협력 노드에 대한 PMI에 적용할 위상 보정 값을 구하고, 상기 구해진 PMI 및 위상 보정 값을 상기 서빙 노드로 피드백하는 것을 특징으로 하는 단말. - 제 12 항에 있어서, 상기 타겟 주파수 대역은 전체 시스템 대역인 것을 특징으로 하는 단말.
- 제 12 항에 있어서,
상기 각 협력 노드에 대한 PMI에 적용할 위상 보정 값은
서로 다른 2개 이상의 협력 노드에 대한 PMI들을 연결하여 하나의 프리코딩 행렬로 만드는데 사용되는 정보임을 특징으로 하는 단말. - 제 12 항에 있어서,
상기 프로세서는 상기 서빙 노드로부터 타겟 주파수 대역 정보를 수신하고 상기 타겟 주파수 대역 정보는 상기 타겟 주파수 대역을 지시하는 것을 특징으로 하는 단말. - 제 15 항에 있어서, 상기 타겟 주파수 대역 정보는 전체 시스템 대역 중 일부 주파수 대역을 상기 타겟 주파수 대역으로 지시하는 것을 특징으로 하는 단말.
- 제 12 항에 있어서,
상기 타겟 주파수 대역 내의 서브 밴드의 개수가 N개인 경우, 상기 각 협력 노드에 대한 PMI에 적용할 위상 보정 값은 N개 이하인 것을 특징으로 하는 단말. 여기서, N은 2 이상의 자연수. - 제 12 항에 있어서,
상기 각 협력 노드에 대한 PMI에 적용할 위상 보정 값 대신
상기 복수의 노드 중 어느 하나인 기준 노드에서 전송한 신호를 수신한 시간과 상기 각 협력 노드가 전송한 신호를 수신한 시간의 차이값을 구하여 피드백하는 것을 특징으로 하는 단말. - 제 18 항에 있어서,
상기 차이값은 상기 타겟 주파수 대역에 대해 하나만 피드백하는 것을 특징으로 하는 단말. - 제 19 항에 있어서, 상기 차이값은 미리 정해진 복수의 시간 구간에 각각 대응하는 인덱스로 주어지는 것을 특징으로 하는 단말.
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EP11856675.1A EP2670057A4 (en) | 2011-01-27 | 2011-12-16 | Channel status information feedback method and apparatus in multi-node system |
JP2013550387A JP5662588B2 (ja) | 2011-01-27 | 2011-12-16 | 多重ノードシステムにおけるチャネル状態情報フィードバック方法及び装置 |
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US20130308542A1 (en) | 2013-11-21 |
US9173130B2 (en) | 2015-10-27 |
CN103339873B (zh) | 2016-04-20 |
EP2670057A1 (en) | 2013-12-04 |
JP2014508447A (ja) | 2014-04-03 |
EP2670057A4 (en) | 2017-06-28 |
CN103339873A (zh) | 2013-10-02 |
JP5662588B2 (ja) | 2015-02-04 |
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