WO2014162796A1 - 無線基地局、ユーザ端末および無線通信方法 - Google Patents
無線基地局、ユーザ端末および無線通信方法 Download PDFInfo
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- WO2014162796A1 WO2014162796A1 PCT/JP2014/054418 JP2014054418W WO2014162796A1 WO 2014162796 A1 WO2014162796 A1 WO 2014162796A1 JP 2014054418 W JP2014054418 W JP 2014054418W WO 2014162796 A1 WO2014162796 A1 WO 2014162796A1
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- base station
- user terminal
- carriers
- radio base
- reference signal
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B17/00—Monitoring; Testing
- H04B17/30—Monitoring; Testing of propagation channels
- H04B17/309—Measuring or estimating channel quality parameters
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04J—MULTIPLEX COMMUNICATION
- H04J11/00—Orthogonal multiplex systems, e.g. using WALSH codes
- H04J11/0023—Interference mitigation or co-ordination
- H04J11/005—Interference mitigation or co-ordination of intercell interference
- H04J11/0056—Inter-base station aspects
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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
- H04L5/0001—Arrangements for dividing the transmission path
- H04L5/0003—Two-dimensional division
- H04L5/0005—Time-frequency
- H04L5/0007—Time-frequency the frequencies being orthogonal, e.g. OFDM(A), DMT
- H04L5/001—Time-frequency the frequencies being orthogonal, e.g. OFDM(A), DMT the frequencies being arranged in component carriers
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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
- H04L5/0048—Allocation of pilot signals, i.e. of signals known to the receiver
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04W—WIRELESS COMMUNICATION NETWORKS
- H04W24/00—Supervisory, monitoring or testing arrangements
- H04W24/08—Testing, supervising or monitoring using real traffic
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04W—WIRELESS COMMUNICATION NETWORKS
- H04W72/00—Local resource management
- H04W72/04—Wireless resource allocation
- H04W72/044—Wireless resource allocation based on the type of the allocated resource
- H04W72/0453—Resources in frequency domain, e.g. a carrier in FDMA
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04W—WIRELESS COMMUNICATION NETWORKS
- H04W72/00—Local resource management
- H04W72/20—Control channels or signalling for resource management
- H04W72/23—Control channels or signalling for resource management in the downlink direction of a wireless link, i.e. towards a terminal
Definitions
- the present invention relates to a radio base station, a user terminal, and a radio communication method in a next-generation mobile communication system in which at least a part of a macro cell and a small cell are arranged to overlap each other.
- LTE Long Term Evolution
- LTE successor systems for example, LTE Advanced, FRA (Future Radio Access), 4G, etc.
- a wireless communication system for example, also called HetNet (Heterogeneous Network)
- small cells including picocells, femtocells, etc.
- Non-Patent Document 1 Non-Patent Document 1
- a scenario using the same frequency band in both the macro cell and the small cell for example, also called co-channel
- a scenario using different frequency bands in the macro cell and the small cell for example, separate frequency
- a relatively low frequency band for example, 2 GHz
- a relatively high frequency band for example, 3.5 GHz or 10 GHz
- a plurality of carriers for example, component carrier (CC)
- CC component carrier
- the user terminal measures the reception quality of a small cell in the vicinity and reports the measurement result to the wireless base station. It is conceivable to determine a small cell to be connected by the user terminal based on the measurement result fed back. In this case, the problem is how the user terminal measures the reception quality of the small cell.
- the present invention has been made in view of this point, and an object of the present invention is to provide a radio base station, a user terminal, and a radio communication method capable of appropriately measuring the reception quality of a small cell on the user terminal side. .
- a radio base station is a radio base station that communicates with a user terminal using a plurality of carriers obtained by dividing a communication band into a plurality, and generates a reference signal for the user terminal to measure reception quality A generation unit, and an allocation unit that controls allocation of the reference signal, and when any of the plurality of carriers is not transmitted, the allocation unit has zero power at a predetermined resource position of a specific carrier. It is characterized by setting RS.
- the present invention it is possible to appropriately measure the reception quality of the small cell on the user terminal side.
- FIG. 1 is a conceptual diagram of a radio communication system (separate frequency) using different frequency bands for a macro cell and a small cell.
- a macro cell M using a relatively low frequency (carrier) F1 such as 2 GHz or 800 MHz and a small using a relatively high frequency (carrier) F2 such as 3.5 GHz.
- F1 relatively low frequency
- F2 relatively high frequency
- the cell S is geographically overlapped.
- a radio base station (hereinafter referred to as a macro base station) that forms a macro cell M
- a radio base station hereinafter referred to as a small base station
- a user terminal that communicates with the small base station.
- the macro base station (macro cell M) and the small base station (small cell S) are connected by a relatively low-speed (medium delay) line (Non-Ideal backhaul) such as an X2 interface.
- a relatively low-speed (medium delay) line such as an X2 interface.
- they may be connected by a relatively high-speed (low delay) line (Ideal backhaul) such as an optical fiber.
- the small base stations may be connected by a relatively low speed (medium delay) line (Non-Ideal backhaul) such as an X2 interface, or a relatively high speed (low delay) such as an optical fiber. ) Line (Ideal backhaul).
- a relatively low speed (medium delay) line such as an X2 interface
- a relatively high speed (low delay) such as an optical fiber.
- Line Ideal backhaul
- the small base station may be a remote radio head station (RRH station) connected to the macro base station.
- RRH station remote radio head station
- FIG. 2A is an explanatory diagram showing an example of arrangement of frequency regions used by the macro cell and the small cell, respectively.
- each small cell S can communicate using a plurality of carriers (or resource blocks (RBs)).
- RBs resource blocks
- a plurality of component carriers (CC: Component Carrier) having a bandwidth of 20 MHz are bundled (five in FIG. 2A) to increase the bandwidth. That is, each small cell S has a bandwidth of 100 MHz (20 MHz ⁇ 5) configured by CC # 1 to CC # 5.
- FIG. 2B is an explanatory diagram showing a conventional measurement method.
- the user terminal measures reception quality of all 5CCs in the small cell 1 and reports to the base station (for example, a macro base station). To do.
- the same measurement is performed for the small cell 2 and the small cell 3. That is, the user terminal needs to measure and report the received power from the neighboring small cells for each carrier.
- the user terminal measures RSRP (Reference Signal Received Power) and RSSI (Received Signal Strength Indicator) based on CRS (Cell specific Reference Signal) received from each small cell. Then, the user terminal reports RSRP and RSRQ (Reference Signal Received Quality) to the base station.
- RSRP Reference Signal Received Power
- RSSI Received Signal Strength Indicator
- CRS Cell specific Reference Signal
- RSRP means the received signal power of a specific cell and is represented by the following formula (1).
- RSSI means the total received signal power of all cells and is expressed by the following equation (2).
- N indicates the number of resource blocks (RB) in the RSSI measurement band.
- RSRQ means the ratio of RSRP and RSSI and is represented by the following formula (3).
- FIG. 3 shows an example of a resource grid (frequency vs. time) possessed by each cell and each CC.
- CRS is a cell-specific reference signal, and RSRP and RSRQ are measured based on CRS.
- CSI-RS Channel State Information Reference Signal
- CQI Channel Quality Indicator
- PMI Precoding Matrix Indicator
- RI Rank Indicator
- CSI-RS uses two consecutive symbols that do not collide with CRS, and is multiplexed into a time-frequency resource.
- ZP-CSI-RS zero power CSI-RS
- NZP-CSI-RS non-zero power CSI-RS
- ZP-CSI-RS transmission power is not distributed to resources to which CSI-RS is allocated, and CSI-RS is muted.
- NZP-CSI-RS transmission power is distributed to resources to which CSI-RS is allocated.
- the user terminal needs to measure the reception power of the reference signal (CRS) for each CC and perform feedback to the base station. . Therefore, when the number of CCs used by the small cell is large, the measurement process may be complicated.
- CRS reference signal
- the present inventors have conceived a simplified measurement method as shown in FIG. 2C. Specifically, even if the small cell uses a plurality of carriers, the user terminal performs measurement using a certain CC (for example, CC # 1). That is, the measurement is performed assuming that the reception quality of the other carriers (remaining CC # 2 to CC # 5) is the same as the reception quality of CC # 1.
- CC # 1 for example, CC # 1
- This method has an advantage that even if the small cell uses a plurality of carriers, complicated processing of the user terminal in the measurement is reduced. There is also an advantage that the overhead of the reference signal for measurement can be reduced.
- interference control Inter-Cell Interference Coordination
- CC Carrier
- a specific CC is not transmitted (muted) in an interfering cell that interferes with neighboring cells.
- each CC since the muting state is controlled for each CC of the neighboring cell, each CC may have a different RSSI due to a different muting (non-transmission) state for each cell. .
- the small cell 3 is not transmitted in CC # 2, and the small cell 2 is not transmitted in CC # 3.
- the RSRPs in CC # 1 to CC # 5 of the small cell 1 are all at the same level as shown in FIG. 4B.
- RSSI in CC # 1 to CC # 5 is expressed as follows.
- RSSI on CC # 1 N (S 1 + S 2 + S 3 )
- RSSI on CC # 2 N (S 1 + S 2 )
- RSSI on CC # 3 N (S 1 + S 3 )
- RSSI on CC # 4 N (S 1 + S 2 + S 3 )
- RSSI on CC # 5 N (S 1 + S 2 + S 3 )
- the present inventors pay attention to this point, and in a communication system in which a small cell uses multiple CCs, when a user terminal performs measurement using a certain CC (for example, CC # 1), CC # 1
- CC # 1 a certain CC (for example, CC # 1)
- the present invention was completed by finding a method for measuring a plurality of RSSIs.
- the reference signal for measuring the received signal power (RSRP) of each cell and the case where any CC is not transmitted in each cell Zero power RS (ZP-RS) for measuring the total received signal power of CC is set.
- the update rule (updating rule) for obtaining the total received signal power of the CC when any CC is not transmitted in each cell is notified to the user terminal.
- the base station refers to either a macro base station or a small base station unless otherwise specified.
- each small cell is configured by CC # 1 to CC # 5, small cell 3 is not transmitted in CC # 2, and small cell in CC # 3.
- a case where 2 is no transmission will be described as an example.
- the first mode is not non-transmitted and can be applied even when the power is smaller than other CCs.
- NZP-CSI-RS can be used as ZP-RS.
- the base station sets a plurality of ZP-RSs for CC # 1. That is, a small cell that puts one of CC # 2 to CC # 5 in a muting state (no transmission) sets ZP-RS in CC # 1. Further, the base station notifies the user terminal of a measurement region as shown in FIG. 5B.
- CC # 2 is not transmitted in the small cell 3. Therefore, the base station of the small cell 3 sets ZP-RS1 for CC # 1 so as to synchronize with the timing when CC # 2 is not transmitted. As a result, CC # 2 can be simulated in the resource area where ZP-RS1 of CC # 1 is set.
- CC # 3 is not transmitted. Therefore, the base station of the small cell 2 sets ZP-RS2 for CC # 1 so as to synchronize with the timing when CC # 3 is not transmitted. As a result, CC # 3 can be simulated in the resource area in which ZP-RS2 of CC # 1 is set.
- ZP-RS1 and ZP-RS2 are set to different resource positions in order to place different CCs in the muting state in each cell. Further, the resource position of the ZP-RS set in CC # 1 in order to simulate other CC # 2 to CC # 5 may be defined in advance or may be notified to the user terminal. For example, a CSI-RS configuration that has already been defined can be used.
- the user terminal measures RSSI from a plurality of set ZP-RSs.
- the RSSI measured from the resource simulating CC # 2 by setting ZP-RS1 in the small cell 3 and the resource simulating CC # 3 by setting ZP-RS2 in the small cell 2 is: Each is expressed as follows.
- RSSI on ZP-RS1 N (S 1 + S 2 )
- RSSI on ZP-RS2 N (S 1 + S 3 )
- FIG. 6 is a diagram showing a resource grid in each CC of the small cells 1 to 3 shown in FIG. 5A.
- a user terminal measures RSRP / RSSI in CC # 1 of each small cell (small cell 1 to small cell 3), respectively.
- the user terminal measures RSSI in a plurality of CCs at CC # 1.
- the user terminal measures the RSRP in CC # 1 of each small cell based on the CRS. Moreover, a user terminal measures RSSI in CC # 1 based on CRS.
- the user terminal measures the RSSI in CC # 3 in which the small cell 2 is not transmitted based on the ZP-CSI-RS (ZP-RS2) set in CC # 1. Further, the user terminal similarly measures RSSI in CC # 2 in which the small cell 3 is not transmitted based on ZP-CSI-RS (ZP-RS1) set in CC # 1.
- the reference signals are concentrated on the resource grid of CC # 1, and the remaining CC # 2 to CC # 5 are concentrated. It is possible to reduce overhead (reference signal arrangement density).
- a plurality of RSSIs can be newly defined in 1 CC based on a plurality of ZP-RSs. This is useful when a plurality of cells independently perform quasi-static control such as no transmission in each CC.
- the above method can also be applied when the user terminal generates channel state information (CSI) based on CSI-RS.
- CSI channel state information
- NZP-CSI-RS is used for estimating the desired signal power
- ZP-CSI-RS is used for estimating the interference signal power.
- the CSI in CC # 1 is calculated.
- NZP-CSI-RS is used for desired signal power estimation
- ZP-CSI-RS is used for interference signal power estimation to calculate CSI in CC # 2.
- the interference signal estimation ZP-CSI-RS has a problem of wasting resources because the same interference signal estimation resource is set in a plurality of CCs.
- a reference signal for interference signal estimation is selectively set to a specific CC resource.
- ZP-CSI-RS is selectively set in CC # 1 of small cell 1.
- the user terminal calculates desired signal strength in each CC based on NZP-CSI-RS in each CC (CC # 1, CC # 2 shown in FIG. 8) of the small cell 1.
- interference from the outside of the small cell 1 is calculated based on the ZP-CSI-RS arranged in the CC # 1 of the small cell 1.
- the CSI measurement method is extended so as to calculate CSI in each CC based on these.
- a user terminal calculates CSI in each CC of each small cell by one desired signal estimation resource arranged in each CC and one interference signal estimation resource arranged in CC # 1. be able to. As a result, even when each small cell uses a plurality of CCs, it is possible to effectively use radio resources.
- a user terminal updates a plurality of RSSIs according to higher layer signaling from a base station, for example, RRC (Radio Resource Control) signaling or broadcast signals.
- RRC Radio Resource Control
- the base station sets and notifies an updating rule (updating rule) for determining RSSI in each CC to the user terminal.
- an updating rule for determining RSSI in each CC to the user terminal.
- the base station sets an update rule including a cell index and a calculation instruction (indication of addition or subtraction).
- the update rule cooperates with a mute pattern that changes quasi-statically in other cells.
- the user terminal updates a plurality of RSSIs according to this update rule.
- each small cell is configured by CC # 1 to CC # 5, and small cell 3 is not transmitted in CC # 2.
- a case where the small cell 2 is not transmitted in CC # 3 will be described as an example.
- the base station determines that the small cell 3 is in the muting state (no transmission) in CC # 2.
- the base station represents the RSSI of CC # 2 as follows.
- S3 corresponds to the received power (RSRP) of the small cell 3 in CC # 1.
- RSSI on CC # 2 RSSI on CC # 1-NxS3
- the base station instructs the user terminal to “subtract” the signal power of the small cell 3.
- the user terminal that has received the instruction subtracts the RSRP of the small cell 3 from the RSSI of the CC # 1, as shown below, using the RSSI of the CC # 1 and the RSRP of the small cell 3 measured in advance.
- the RSSI in # 2 is updated and fed back to the base station.
- RSSI on CC # 2 measured RSSI on CC # 1-Nx measured RSRP on Cell3
- the base station determines that the small cell 2 is in the muting state (no transmission) in CC # 3. Therefore, the base station instructs the user terminal to “subtract” the signal power of the small cell 2.
- the user terminal receiving the instruction uses the RSSI of the CC # 1 and the RSRP of the small cell 2 measured in advance, and subtracts the RSRP of the small cell 2 from the RSSI of the CC # 1, as expressed below.
- the RSSI in # 3 is updated and fed back to the base station.
- RSSI on CC # 3 measured RSSI on CC # 1-Nx measured RSRP on Cell2
- RSRP can be measured by one or a plurality of reference signals, for example, CRS, CSI-RS, detection signals (discovery signals, discovery reference signals).
- reference signals for example, CRS, CSI-RS, detection signals (discovery signals, discovery reference signals).
- FIG. 9 is a diagram showing a resource grid in each CC of the small cells 1 to 3 shown in FIG. 5A.
- the user terminal measures RSRP1 based on the CRS of the small cell 1.
- a user terminal measures RSRP2 based on CRS of small cell 2, and measures RSRP3 based on CRS of small cell 3.
- the user terminal measures the RSSI of CC # 1 based on the CRS of CC # 1.
- the user terminal updates the RSSI according to the update rule instructed from the base station. Specifically, the user terminal updates the RSSI of CC # 2 by subtracting RSRP3 from the RSSI of CC # 1. Also, the user terminal updates the RSSI of CC # 3 by subtracting RSRP2 from the RSSI of CC # 1.
- the base station instructs the update rule to the user terminal, and updates the RSSI by calculating according to the RSRP / RSSI measured by the user terminal and the update rule, whereby the transmission state of each cell in each CC ( A plurality of RSSIs can be appropriately measured according to (transmission / non-transmission).
- a plurality of RSSIs can be newly defined in 1 CC according to update information set by the base station. This is useful for quasi-static CC level control such as no transmission and power control.
- FIG. 10 is a schematic configuration diagram of the radio communication system according to the present embodiment.
- the radio communication system 1 includes a macro base station 11 that forms a macro cell C1 as a first cell, and a small cell C2 that is arranged in the macro cell C1 and that is a second cell narrower than the macro cell C1.
- the user terminal 20 is arrange
- the user terminal 20 is arranged in the macro cell C1 and each small cell C2.
- the user terminal 20 is configured to be able to wirelessly communicate with the macro base station 11 and / or the small base station 12.
- the user terminal 20 can communicate with a plurality of small base stations 12 by integrating component carriers used in each small cell C2 (carrier aggregation).
- the user terminal 20 can communicate with the macro base station 11 and the small base station 12 by integrating the component carriers respectively used in the macro cell C1 and the small cell C2.
- Communication between the user terminal 20 and the macro base station 11 is performed using a carrier having a relatively low frequency band (for example, 2 GHz).
- a carrier having a relatively high frequency band for example, 3.5 GHz
- the same frequency band may be used by the macro base station 11 and the small base station 12.
- the macro base station 11 and each small base station 12 may be connected by a relatively low speed (medium delay) line (Non-Ideal backhaul) such as an X2 interface, or may be relatively connected by an optical fiber or the like. It may be connected by a high-speed (low delay) line (Ideal backhaul) or may be connected wirelessly. Also, the small base stations 12 may be connected by a relatively low speed (medium delay) line (Non-Ideal backhaul) such as an X2 interface, or a relatively high speed (low delay) such as an optical fiber. It may be connected by a line (Ideal backhaul) or may be connected wirelessly.
- a relatively low speed (medium delay) line such as an X2 interface
- a relatively high speed (low delay) such as an optical fiber. It may be connected by a line (Ideal backhaul) or may be connected wirelessly.
- the macro base station 11 and each small base station 12 are connected to the higher station apparatus 30 and connected to the core network 40 via the higher station apparatus 30.
- the upper station device 30 includes, for example, an access gateway device, a radio network controller (RNC), a mobility management entity (MME), and the like, but is not limited thereto.
- RNC radio network controller
- MME mobility management entity
- the macro base station 11 is a radio base station having a relatively wide coverage, and may be referred to as an eNodeB (eNB), a radio base station, a transmission point, or the like.
- the small base station 12 is a radio base station having local coverage, and may be called an RRH (Remote Radio Head), a pico base station, a femto base station, a Home eNodeB, a transmission point, an eNodeB (eNB), or the like.
- the user terminal 20 is a terminal that supports various communication schemes such as LTE and LTE-A, and may include not only a mobile communication terminal but also a fixed communication terminal.
- a downlink shared channel (PDSCH: Physical Downlink Shared Channel) shared by each user terminal 20, a downlink control channel (PDCCH: Physical Downlink Control Channel, EPDCCH: Enhanced) Physical Downlink Control Channel), PCFICH, PHICH, broadcast channel (PBCH), etc.
- PDSCH Physical Downlink Shared Channel
- PDCCH Physical Downlink Control Channel
- EPDCCH Enhanced Physical Downlink Control Channel
- PCFICH Physical Downlink Control Channel
- PHICH Physical Downlink Control Channel
- PBCH broadcast channel
- an uplink shared channel (PUSCH: Physical Uplink Shared Channel) shared by each user terminal 20 and an uplink control channel (PUCCH: Physical Uplink Control Channel) are used as uplink communication channels. It is done. User data and higher layer control information are transmitted by PUSCH. Also, downlink radio quality information (CQI: Channel Quality Indicator), delivery confirmation information (ACK / NACK), and the like are transmitted by PUCCH.
- PUSCH Physical Uplink Shared Channel
- PUCCH Physical Uplink Control Channel
- each of the user terminal 20, the macro base station 11, and the small base station 12 has hardware including a communication interface, a processor, a memory, a transmission / reception circuit, and the like, and a software module executed by the processor is stored in the memory. Is remembered.
- the configuration shown in FIGS. 11 to 14 may be realized by the hardware described above, may be realized by a software module executed by a processor, or may be realized by a combination of both.
- FIG. 11 is an overall configuration diagram of the radio base station 10 (including the radio base stations 11 and 12) according to the present embodiment.
- the radio base station 10 includes a plurality of transmission / reception antennas 101 for MIMO transmission, an amplifier unit 102, a transmission / reception unit 103, a baseband signal processing unit 104, a call processing unit 105, and a transmission path interface 106. Yes.
- User data transmitted from the radio base station 10 to the user terminal 20 via the downlink is input from the higher station apparatus 30 to the baseband signal processing unit 104 via the transmission path interface 106.
- the baseband signal processing unit 104 performs PDCP layer processing, user data division / combination, RLC layer transmission processing such as RLC (Radio Link Control) retransmission control transmission processing, MAC (Medium Access Control) retransmission control, for example, HARQ transmission processing, scheduling, transmission format selection, channel coding, Inverse Fast Fourier Transform (IFFT) processing, and precoding processing are performed and transferred to each transceiver 103.
- RLC layer transmission processing such as RLC (Radio Link Control) retransmission control transmission processing, MAC (Medium Access Control) retransmission control, for example, HARQ transmission processing, scheduling, transmission format selection, channel coding, Inverse Fast Fourier Transform (IFFT) processing, and precoding processing are performed and transferred to each transceiver 103.
- HARQ transmission processing scheduling, transmission format selection, channel coding, Inverse Fast Fourier Transform (IFFT) processing, and precoding processing are performed and transferred to each transceiver 103.
- IFFT Inverse Fast Fourier Transform
- the baseband signal processing unit 104 notifies the control information for communication in the cell to the user terminal 20 through the broadcast channel.
- the information for communication in the cell includes, for example, the system bandwidth in the uplink or the downlink. Moreover, you may notify the information regarding TPC mentioned above to a user terminal using an alerting
- the radio base station 12 functioning as a central control station can notify the user terminal of information using a broadcast channel. it can.
- Each transmission / reception unit 103 converts the baseband signal output by precoding from the baseband signal processing unit 104 for each antenna to a radio frequency band.
- the amplifier unit 102 amplifies the frequency-converted radio frequency signal and transmits the amplified signal using the transmission / reception antenna 101.
- radio frequency signals received by the respective transmission / reception antennas 101 are amplified by the amplifier units 102 and frequency-converted by the respective transmission / reception units 103. It is converted into a baseband signal and input to the baseband signal processing unit 104.
- the baseband signal processing unit 104 performs FFT processing, IDFT processing, error correction decoding, MAC retransmission control reception processing, RLC layer, and PDCP layer reception processing on user data included in the input baseband signal.
- the data is transferred to the higher station apparatus 30 via the transmission path interface 106.
- the call processing unit 105 performs call processing such as communication channel setting and release, status management of the radio base station 10, and radio resource management.
- FIG. 12 is a main functional configuration diagram of the baseband signal processing unit 104 included in the macro base station (wireless base station 11) according to the present embodiment.
- the baseband signal processing unit 104 included in the radio base station 11 includes a scheduler 111, a measurement unit 112, a higher control signal generation unit 113, and a UE connected cell selection unit 114. Is done.
- the scheduler 111 performs scheduling of downlink user data transmitted on the PDSCH, downlink control information transmitted on the PDCCH and / or enhanced PDCCH (EPDCCH), and reference signals. Specifically, the scheduler 111 assigns radio resources based on instruction information from the higher station apparatus 30 and feedback information from each user terminal 20 (for example, CSI including CQI, RI, etc.). Note that the scheduler 111 may be configured to schedule each small base station 12.
- the measuring unit 112 measures the radio quality of each small cell C2. By this measurement, the macro base station 11 confirms transmission / non-transmission (mute pattern) for each CC of each small cell C2.
- the upper control signal generation unit 113 uses CC # 1 to virtually simulate the reception quality state of CC # 2 to CC # 5. A higher control signal for setting a plurality of ZP-RSs for 1 is generated. Further, when applying the second aspect, the upper control signal generation unit 113 generates an upper control signal for setting and notifying an updating rule for determining RSSI in each CC. To do.
- the UE connected cell selection unit 114 determines the small base station 12 to which the user terminal 20 should connect based on the measurement result fed back from the user terminal 20.
- FIG. 13 is a main functional configuration diagram of the baseband signal processing unit 104 included in the small base station (wireless base station 12) according to the present embodiment.
- the baseband signal processing unit 104 included in the radio base station 12 includes a scheduler 121, a reference signal generation unit 122, and an allocation unit 123.
- the small base station 12 operates as a control station, that is, when receiving a measurement report from the user terminal 20, the small base station 12 includes a UE connected cell selection unit 114 included in the macro base station 11. May be.
- the scheduler 121 schedules downlink user data transmitted on the PDSCH, downlink control information transmitted on the PDCCH and / or enhanced PDCCH (EPDCCH), and reference signals. Specifically, the scheduler 121 allocates radio resources based on instruction information from the higher station apparatus 30 and feedback information from each user terminal 20 (for example, CSI including CQI, RI, etc.). In addition, when the scheduler 111 in the macro base station 11 performs scheduling of each small base station 12, a configuration without the scheduler 121 may be employed.
- the reference signal generation unit 122 generates a reference signal for the user terminal 20 to measure reception quality.
- the reference signal generator 122 generates a cell-specific reference signal (CRS) for measuring received power, zero power CSI-RS, and the like.
- CRS cell-specific reference signal
- the assigning unit 123 assigns the reference signal generated by the reference signal generating unit 122.
- the allocating unit 123 allocates a ZP-RS to a predetermined resource position of a specific CC when any of a plurality of CCs is not transmitted.
- the assigning unit 123 assigns the CRS and the ZP-RS to different resource positions.
- the assigning unit 123 assigns a CRS placement density assigned to a specific CC higher than a CRS placement density assigned to another CC.
- FIG. 14 is a block diagram showing a configuration of the user terminal 20 according to the present embodiment.
- the user terminal 20 includes a reception unit 201, a measurement unit 202, and a transmission unit 203.
- the receiving unit 201 receives downlink signals (downlink data signal, downlink control signal, downlink reference signal, broadcast signal, etc.) from the macro base station 11 and / or the small base station 12.
- the receiving unit 201 receives higher layer control information from the macro base station 11 and / or the small base station 12.
- the upper layer control information is control information that is RRC (Radio Resource Control) signaling or MAC signalled.
- the receiving unit 201 receives from the macro base station 11 a signal (for example, a CSI-RS configuration) for notifying the user terminal 20 of the measurement area in CC # 1 of each small cell C2. Or the receiving part 201 receives the signal for notifying the update rule containing the instruction
- a signal for example, a CSI-RS configuration
- the measuring unit 202 measures the reception quality using the reference signal transmitted from the radio base station.
- the measurement unit 202 is set by a radio base station that does not transmit any of a reference signal assigned to a specific CC among a plurality of CCs and a plurality of CCs. A plurality of reception qualities are measured based on the ZP-RS.
- the measurement unit 202 based on the update rule notified when any one of the plurality of CCs is not transmitted, receives a plurality of total receptions from the measured reception quality.
- Signal power (RSSI) is acquired.
- the transmission unit 203 transmits an uplink signal (uplink data signal, uplink control signal, uplink reference signal, etc.) to the macro base station 11 and / or the small base station 12. Further, the transmission unit 203 transmits higher layer control information to the macro base station 11 and / or the small base station 12.
- an uplink signal uplink data signal, uplink control signal, uplink reference signal, etc.
- the transmission unit 203 transmits a measurement report (RSRP / RSRQ) based on RSRP / RSSI measured by the measurement unit 202 to the macro base station 11.
- RSRP / RSRQ a measurement report
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Abstract
Description
RSSI on CC#1=N(S1+S2+S3)
RSSI on CC#2=N(S1+S2)
RSSI on CC#3=N(S1+S3)
RSSI on CC#4=N(S1+S2+S3)
RSSI on CC#5=N(S1+S2+S3)
なお、本実施の形態において、基地局とは、特に明記しない限り、マクロ基地局またはスモール基地局のいずれかを指すものとする。
第1の態様では、複数のRSSIを、CC#1においてセル毎に設定された複数のZP-RSに基づいて測定する場合について説明する。なお、第1の態様において、ZP-RSとしては、ZP-CSI-RSまたはNZP-CSI-RSを利用することができる。
RSSI on ZP-RS1=N(S1+S2)
RSSI on ZP-RS2=N(S1+S3)
第2の態様では、複数のRSSIを、基地局からのハイヤレイヤシグナリング、たとえばRRC(Radio Resource Control)シグナリングまたは報知信号に従って、ユーザ端末がアップデートする場合について説明する。
RSSI on CC#2=RSSI on CC#1-NxS3
RSSI on CC#2=measured RSSI on CC#1-Nx measured RSRP on Cell3
RSSI on CC#3=measured RSSI on CC#1-Nx measured RSRP on Cell2
以下、本実施の形態に係る無線通信システムについて、詳細に説明する。この無線通信システムでは、上述の第1、第2の態様に係るメジャメント法が適用される。
Claims (9)
- 通信帯域を複数に分割した複数のキャリアを利用してユーザ端末と通信を行う無線基地局であって、
ユーザ端末が受信品質を測定するための参照信号を生成する生成部と、
前記参照信号の割当てを制御する割当て部と、を有し、
前記複数のキャリアのいずれかを無送信とする場合に、前記割当て部は、特定のキャリアの所定リソース位置にゼロパワーRSを設定することを特徴とする無線基地局。 - 前記割当て部は、受信電力測定用のセル固有参照信号(CRS)と、前記ゼロパワーRSと、を異なるリソース位置に割当てることを特徴とする請求項1に記載の無線基地局。
- 前記ゼロパワーRSは、ゼロパワーCSI-RSであることを特徴とする請求項2に記載の無線基地局。
- 前記割当て部は、特定のキャリアに割当てるCRSの配置密度を、他のキャリアに割当てるCRSの配置密度よりも高く割り当てることを特徴とする請求項1に記載の無線基地局。
- 前記ゼロパワーCSI-RSを用いて、チャネル状態の測定を行うことを特徴とする請求項3に記載の無線基地局。
- 無線基地局と複数のキャリアを利用して通信を行うユーザ端末であって、
無線基地局から送信される参照信号を用いて受信品質を測定する測定部と、
受信品質に関する情報をフィードバックする送信部と、を具備し、
前記測定部は、複数のキャリアのうち1つのキャリアに割当てられたセル固有参照信号(CRS)と、ゼロパワーRSとに基づいて、複数の受信品質を測定することを特徴とするユーザ端末。 - 前記ゼロパワーRSは、複数のキャリアのうち少なくともいずれかを無送信とする無線基地局により設定されることを特徴とする請求項6に記載のユーザ端末。
- 無線基地局と複数のキャリアを利用して通信を行うユーザ端末であって、
無線基地局から送信される参照信号を用いて受信品質を測定する測定部と、
受信品質に関する情報をフィードバックする送信部と、を具備し、
前記測定部は、複数のキャリアのいずれかが無送信となる場合に通知される更新規則に基づいて、測定した受信品質から複数の合計受信信号電力(RSSI)を取得することを特徴とするユーザ端末。 - 通信帯域を複数に分割した複数のキャリアを利用してユーザ端末と無線基地局との無線通信方法であって、
前記無線基地局が、前記複数のキャリアのいずれかを無送信とする場合に、特定のキャリアの所定リソース位置にゼロパワーRSを設定する工程と、
前記ユーザ端末が、複数のキャリアのうち1つのキャリアに割当てられた参照信号と、複数のキャリアのいずれかを無送信とする無線基地局により設定されたゼロパワーRSとに基づいて、複数の受信品質を測定する工程と、受信品質に関する情報をフィードバックする工程と、を有することを特徴とする無線通信方法。
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KR20190068611A (ko) | 2016-10-21 | 2019-06-18 | 텔레호낙티에볼라게트 엘엠 에릭슨(피유비엘) | 다운링크 제어 채널들과 비주기적인 채널 상태 정보-기준 신호들 사이의 충돌 회피 |
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