WO2013141147A1 - 移動通信システム及び移動通信方法 - Google Patents
移動通信システム及び移動通信方法 Download PDFInfo
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- WO2013141147A1 WO2013141147A1 PCT/JP2013/057361 JP2013057361W WO2013141147A1 WO 2013141147 A1 WO2013141147 A1 WO 2013141147A1 JP 2013057361 W JP2013057361 W JP 2013057361W WO 2013141147 A1 WO2013141147 A1 WO 2013141147A1
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- base station
- radio base
- uplink signal
- anchor radio
- before decoding
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04W—WIRELESS COMMUNICATION NETWORKS
- H04W76/00—Connection management
- H04W76/10—Connection setup
- H04W76/15—Setup of multiple wireless link connections
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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
- H04W72/21—Control channels or signalling for resource management in the uplink direction of a wireless link, i.e. towards the network
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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
- H04B7/026—Co-operative diversity, e.g. using fixed or mobile stations as relays
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04W—WIRELESS COMMUNICATION NETWORKS
- H04W28/00—Network traffic management; Network resource management
- H04W28/16—Central resource management; Negotiation of resources or communication parameters, e.g. negotiating bandwidth or QoS [Quality of Service]
Definitions
- the present invention relates to a mobile communication system that receives an uplink signal transmitted from a radio terminal in cooperation with a plurality of radio base stations, and a mobile communication method used in the mobile communication system.
- a mobile communication system in which uplink signals transmitted from wireless terminals are received in cooperation by a plurality of wireless base stations.
- selective combining of uplink signals received by a plurality of radio base stations is performed.
- an uplink signal is transmitted via PUSCH (Physical Uplink Shared Channel).
- PUSCH Physical Uplink Shared Channel
- the plurality of radio base stations include one anchor radio base station and the remaining non-anchor radio base stations.
- the non-anchor radio base station transmits the uplink signal before decoding to the anchor radio base station via the backhaul network.
- the anchor radio base station selectively combines the uplink signal before decoding transmitted from the radio terminal and the uplink signal before decoding received from the non-anchor radio base station.
- the mobile communication system is a system in which an uplink signal transmitted from a radio terminal is received in cooperation by a plurality of radio base stations.
- the plurality of radio base stations include one anchor radio base station and non-anchor radio base stations other than the anchor radio base station.
- the anchor radio base station does not receive an uplink signal before decoding from the non-anchor radio base station via a backhaul network, and performs control of decoding an uplink signal before decoding received from the radio terminal. And when the decoding of the uplink signal before decoding received from the wireless terminal fails, the uplink signal before decoding is transmitted to the non-anchor wireless base station via the backhaul network. And a notification unit for notifying that it should be performed.
- the non-anchor radio base station When the non-anchor radio base station is notified from the anchor radio base station that the uplink signal before decoding should be transmitted, the non-anchor radio base station transmits the uplink signal before decoding to the anchor radio base station.
- a transmitting unit for transmitting is provided.
- the notification unit notifies the bit accuracy of the uplink signal before decoding to be transmitted through the backhaul network.
- the bit precision is a value that directly specifies the precision of the uplink signal before decoding.
- the bit precision is set based on at least one of an uplink signal reception quality before decoding, an uplink signal reception quality after decoding, and an uplink signal modulation and coding scheme.
- the bit accuracy is a value that relatively specifies the accuracy of the uplink signal before decoding.
- the said notification part is the said decoding via said backhaul network with respect to the non-anchor radio base station with which the reception quality of the uplink signal which the said non-anchor radio base station receives satisfy
- the said transmission part is notified from the said anchor radio base station that the uplink signal before the said decoding should be transmitted, and reception quality of the uplink signal which the said non-anchor radio base station receives When the predetermined quality is satisfied, an uplink signal before decoding is transmitted to the anchor radio base station via a backhaul network.
- the mobile communication method is a method in which an uplink signal transmitted from a radio terminal is received in cooperation by a plurality of radio base stations.
- the plurality of radio base stations include one anchor radio base station and non-anchor radio base stations other than the anchor radio base station.
- the anchor radio base station receives an uplink signal before decoding received from the radio terminal without receiving an uplink signal before decoding from the non-anchor radio base station via a backhaul network. And when the anchor radio base station fails to decode the uplink signal before decoding received from the radio terminal, the backhaul network is connected to the non-anchor radio base station.
- the uplink signal before decoding is transmitted from the station to the anchor radio base station And a step.
- FIG. 1 is a diagram showing a mobile communication system 100 according to the first embodiment.
- FIG. 2 is a diagram illustrating a radio frame according to the first embodiment.
- FIG. 3 is a diagram illustrating radio resources according to the first embodiment.
- FIG. 4 is a diagram illustrating an application case according to the first embodiment.
- FIG. 5 is a block diagram showing an anchor radio base station 310A according to the first embodiment.
- FIG. 6 is a block diagram showing the non-anchor radio base station 310B according to the first embodiment.
- FIG. 7 is a sequence diagram showing operations of the mobile communication system 100 according to the first embodiment.
- FIG. 8 is a diagram for explaining the bit accuracy according to the first modification.
- FIG. 9 is a diagram for explaining the bit accuracy according to the first modification.
- FIG. 8 is a diagram for explaining the bit accuracy according to the first modification.
- FIG. 10 is a diagram for explaining the bit accuracy according to the first modification.
- FIG. 11 is a diagram for explaining the bit accuracy according to the first modification.
- FIG. 12 is a sequence diagram showing operations of the mobile communication system 100 according to the first modification.
- FIG. 13 is a sequence diagram showing an operation of the mobile communication system 100 according to the second modification.
- FIG. 14 is a sequence diagram showing operations of the mobile communication system 100 according to the third modification.
- the mobile communication system is a system that receives an uplink signal transmitted from a radio terminal in cooperation with a plurality of radio base stations.
- the plurality of radio base stations include one anchor radio base station and non-anchor radio base stations other than the anchor radio base station.
- the anchor radio base station does not receive an uplink signal before decoding from the non-anchor radio base station via a backhaul network, and performs control of decoding an uplink signal before decoding received from the radio terminal. And when the decoding of the uplink signal before decoding received from the wireless terminal fails, the uplink signal before decoding is transmitted to the non-anchor wireless base station via the backhaul network.
- the non-anchor radio base station When the non-anchor radio base station is notified from the anchor radio base station that the uplink signal before decoding should be transmitted, the non-anchor radio base station transmits the uplink signal before decoding to the anchor radio base station.
- a transmitting unit for transmitting is provided.
- the anchor radio base station when the anchor radio base station fails to decode the uplink signal before decoding received from the radio terminal, the anchor radio base station transmits the uplink before decoding via the backhaul network to the non-anchor radio base station. Notify that a signal should be sent. Therefore, unnecessary transmission of uplink signals before decoding from the non-anchor radio base station to the anchor radio base station is suppressed, and an increase in the load on the backhaul network is suppressed.
- FIG. 1 is a diagram showing a mobile communication system 100 according to the first embodiment.
- the mobile communication system 100 includes a radio terminal 10 (hereinafter referred to as UE 10) and a core network 50.
- the mobile communication system 100 includes a first communication system and a second communication system.
- the first communication system is a communication system that supports, for example, LTE (Long Term Evolution).
- the first communication system includes, for example, a base station 110A (hereinafter referred to as MeNB 110A), a home base station 110B (hereinafter referred to as HeNB 110B), a home base station gateway 120B (hereinafter referred to as HeNB-GW 120B), and an MME 130.
- MeNB 110A a base station 110A
- HeNB 110B home base station gateway 120B
- MME 130 MME
- a radio access network (E-UTRAN; Evolved Universal Terrestrial Radio Access Network) corresponding to the first communication system is configured by MeNB 110A, HeNB 110B, and HeNB-GW 120B.
- the second communication system is a communication system compatible with, for example, UMTS (Universal Mobile Telecommunication System).
- the second communication system includes a base station 210A (hereinafter referred to as MNB 210A), a home base station 210B (hereinafter referred to as HNB 210B), an RNC 220A, a home base station gateway 220B (hereinafter referred to as HNB-GW 220B), and an SGSN 230.
- a radio access network (UTRAN: Universal Terrestrial Radio Access Network) corresponding to the second communication system is configured by an MNB 210A, an HNB 210B, an RNC 220A, and an HNB-GW 220B.
- UTRAN Universal Terrestrial Radio Access Network
- the UE 10 is a device (User Equipment) configured to communicate with the second communication system or the first communication system.
- the UE 10 has a function of performing wireless communication with the MeNB 110A and the HeNB 110B.
- the UE 10 has a function of performing wireless communication with the MNB 210A and the HNB 210B.
- the MeNB 110A is a device (evolved NodeB) that manages the general cell 111A and performs radio communication with the UE 10 existing in the general cell 111A.
- the HeNB 110B is a device (Home evolved NodeB) that manages the specific cell 111B and performs radio communication with the UE 10 existing in the specific cell 111B.
- the HeNB-GW 120B is an apparatus (Home evolved NodeB Gateway) that is connected to the HeNB 110B and manages the HeNB 110B.
- the MME 130 is an apparatus (Mobility Management Entity) that manages the mobility of the UE 10 that is connected to the MeNB 110A and has established a wireless connection with the MeNB 110A. Further, the MME 130 is an apparatus that manages the mobility of the UE 10 that is connected to the HeNB 110B via the HeNB-GW 120B and has established a radio connection with the HeNB 110B.
- MME 130 Mobility Management Entity
- the MNB 210A is a device (NodeB) that manages the general cell 211A and performs radio communication with the UE 10 existing in the general cell 211A.
- the HNB 210B is a device (Home NodeB) that manages the specific cell 211B and performs radio communication with the UE 10 existing in the specific cell 211B.
- the RNC 220A is an apparatus (Radio Network Controller) that is connected to the MNB 210A and sets up a radio connection (RRC Connection) with the UE 10 existing in the general cell 211A.
- RRC Connection Radio Connection
- the HNB-GW 220B is a device (Home NodeB Gateway) that is connected to the HNB 210B and sets up a radio connection (RRC Connection) with the UE 10 existing in the specific cell 211B.
- RRC Connection Radio Connection
- SGSN 230 is a device (Serving GPRS Support Node) that performs packet switching in the packet switching domain.
- the SGSN 230 is provided in the core network 50.
- an apparatus MSC: Mobile Switching Center
- MSC Mobile Switching Center
- the general cell and the specific cell should be understood as a function of performing radio communication with the UE 10.
- the general cell and the specific cell are also used as terms indicating a cell coverage area.
- cells such as general cells and specific cells are identified by the frequency, spreading code, time slot, or the like used in the cells.
- the coverage area of general cells is wider than the coverage area of specific cells.
- the general cell is, for example, a macro cell provided by a telecommunications carrier.
- the specific cell is, for example, a femto cell or a home cell provided by a third party other than the communication carrier.
- the specific cell may be a CSG (Closed Subscriber Group) cell or a pico cell provided by a communication carrier.
- the first communication system will be mainly described. However, the following description may be applied to the second communication system.
- an OFDMA Orthogonal Frequency Division Multiple Access
- SC-FDMA Single-Carrier Frequency Multiplex
- a method is used.
- an uplink control channel (PUCCH: Physical Uplink Channel) and an uplink shared channel (PUSCH: Physical Uplink Channel) as uplink channels.
- PUSCH Physical Uplink Channel
- a downlink channel there are a downlink control channel (PDCCH; Physical Downlink Control Channel), a downlink shared channel (PDSCH; Physical Downlink Shared Channel), and the like.
- the uplink control channel is a channel that carries a control signal.
- the control signal includes, for example, CQI (Channel Quality Indicator), PMI (Precoding Matrix Indicator), RI (Rank Indicator), SR (Scheduling Request), ACK / NACK, and the like.
- CQI is a signal notifying the recommended modulation method and coding rate to be used for downlink transmission.
- PMI is a signal indicating a precoder matrix that is preferably used for downlink transmission.
- the RI is a signal indicating the number of layers (number of streams) to be used for downlink transmission.
- SR is a signal requesting allocation of uplink radio resources (resource blocks to be described later).
- ACK / NACK is a signal indicating whether or not a signal transmitted via a downlink channel (for example, PDSCH) has been received.
- the uplink shared channel is a channel that carries a control signal (including the control signal described above) and / or a data signal.
- the uplink radio resource may be allocated only to the data signal, or may be allocated so that the data signal and the control signal are multiplexed.
- the downlink control channel is a channel that carries a control signal.
- the control signals are, for example, Uplink SI (Scheduling Information), Downlink SI (Scheduling Information), and TPC bits.
- Uplink SI is a signal indicating uplink radio resource allocation.
- Downlink SI is a signal indicating downlink radio resource allocation.
- the TPC bit is a signal for instructing increase / decrease in power of a signal transmitted via an uplink channel.
- the downlink shared channel is a channel that carries control signals and / or data signals.
- the downlink radio resource may be allocated only to the data signal, or may be allocated so that the data signal and the control signal are multiplexed.
- TA Triming Advance
- TA is transmission timing correction information between UE10 and MeNB110A, and is measured by MeNB110A based on the uplink signal transmitted from UE10.
- ACK / NACK can be cited as a control signal transmitted via a channel other than the downlink control channel (PDCCH) and the downlink shared channel (PDSCH).
- ACK / NACK is a signal indicating whether or not a signal transmitted via an uplink channel (for example, PUSCH) has been received.
- the broadcast information is information such as MIB (Master Information Block) or SIB (System Information Block).
- FIG. 2 is a diagram illustrating a radio frame in the first communication system.
- one radio frame is composed of 10 subframes, and one subframe is composed of two slots.
- the time length of one slot is 0.5 msec
- the time length of one subframe is 1 msec
- the time length of one radio frame is 10 msec.
- One slot is composed of a plurality of OFDM symbols (for example, 6 OFDM symbols or 7 OFDM symbols) in the downlink.
- one slot is configured by a plurality of SC-FDMA symbols (for example, six SC-FDMA symbols or seven SC-FDMA symbols) in the uplink.
- FIG. 3 is a diagram illustrating radio resources in the first communication system.
- radio resources are defined by a frequency axis and a time axis.
- the frequency is composed of a plurality of subcarriers, and a predetermined number of subcarriers (12 subcarriers) are collectively referred to as a resource block (RB).
- RB resource block
- the time has units such as an OFDM symbol (or SC-FDMA symbol), a slot, a subframe, and a radio frame.
- radio resources can be allocated for each resource block. Also, it is possible to divide and allocate radio resources to a plurality of users (for example, user # 1 to user # 5) on the frequency axis and the time axis.
- the radio resource is allocated by the MeNB 110A. Radio resources are allocated to each UE 10 based on CQI, PMI, RI, and the like.
- FIG. 4 is a diagram for explaining an application scene according to the first embodiment.
- FIG. 4 illustrates a case where one anchor radio base station 310A and a plurality of non-anchor radio base stations 310B are provided as radio base stations.
- the anchor radio base station 310A and the non-anchor radio base station 310B constitute a radio base station group (CoMP set) that cooperatively receives uplink signals transmitted from the UE 10.
- CoMP set radio base station group
- the UE 10 transmits an uplink signal to the anchor radio base station 310A and the non-anchor radio base station 310B.
- the uplink signal transmitted from the UE 10 is encoded.
- the uplink signal transmitted from the UE 10 is transmitted, for example, via the above-described uplink shared channel (PUSCH).
- PUSCH uplink shared channel
- the non-anchor radio base station 310B transmits the uplink signal before decoding to the anchor radio base station 310A via the backhaul network.
- the anchor radio base station 310A performs selective combining of the uplink signal before decoding transmitted from the UE 10 and the uplink signal before decoding received from the non-anchor radio base station 310B.
- the backhaul network may be an X2 interface that directly connects wireless base stations, or may be an S1 interface that connects wireless base stations via an upper node (for example, MME 130).
- the anchor radio base station 310A and the non-anchor radio base station 310B may be radio base stations. That is, in the first embodiment, the anchor radio base station 310A and the non-anchor radio base station 310B are any one of the MeNB 110A, the HeNB 110B, the MNB 210A, and the HNB 210B.
- the anchor radio base station 310A receives the decoding from the UE 10 without receiving the uplink signal before decoding from the non-anchor radio base station 310B via the backhaul network. Decode the previous uplink signal.
- the anchor radio base station 310A fails to decode the uplink signal before decoding received from the UE 10, the anchor radio base station 310A transmits the uplink signal before decoding to the non-anchor radio base station via the backhaul network. Notify you.
- the anchor radio base station 310A receives the uplink signal before decoding transmitted from the UE 10 and the non-anchor radio base station 310B. Performs selective combining of uplink signals before decoding.
- FIG. 5 is a block diagram showing an anchor radio base station 310A according to the first embodiment.
- the anchor radio base station 310A includes a reception unit 313A, a transmission unit 314A, an interface 315A, and a control unit 316A.
- the receiving unit 313A receives an uplink signal from the UE 10 connected to the cell managed by the anchor radio base station 310A.
- the reception unit 313A receives an uplink signal via an uplink shared channel (PUSCH).
- PUSCH uplink shared channel
- the transmission unit 314A transmits a downlink signal to the UE 10 connected to the cell managed by the anchor radio base station 310A. For example, the transmission unit 314A transmits radio resources (scheduling information) allocated by the anchor radio base station 310A.
- the interface 315A is an interface that communicates with other radio base stations via a backhaul network.
- the interface 315A is an X2 interface that directly connects wireless base stations.
- the interface 315A is an S1 interface that connects wireless base stations to each other via an upper node (for example, the MME 130).
- the interface 315A when the interface 315A fails to decode the uplink signal before decoding received from the UE 10, the interface 315A transmits the uplink signal before decoding to the non-anchor radio base station via the backhaul network. Is configured to notify that it should be transmitted.
- the control unit 316A controls the operation of the anchor radio base station 310A. For example, the control unit 316A decodes the uplink signal before decoding received from the UE 10 without receiving the uplink signal before decoding from the non-anchor radio base station 310B via the backhaul network.
- the control unit 316A when decoding of the uplink signal before decoding received from the UE 10 fails, the control unit 316A receives the uplink signal before decoding transmitted from the UE 10 and the non-anchor radio base station 310B. Performs selective combining of uplink signals before decoding. Specifically, the control unit 316A performs the uplink before decoding with the best reception quality among the uplink signal before decoding transmitted from the UE 10 and the uplink signal before decoding received from the non-anchor radio base station 310B. A signal may be selected, and the selected uplink signal before decoding may be decoded.
- control unit 316A determines that the uplink signal before decoding having a quality equal to or higher than a predetermined quality among the uplink signal before decoding transmitted from the UE 10 and the uplink signal before decoding received from the non-anchor radio base station 310B. And the synthesized uplink signal before decoding may be decoded. Note that the control unit 316A combines all the uplink signals before decoding transmitted from the UE 10 and the uplink signals before decoding received from the non-anchor radio base station 310B, and the combined uplink signals before decoding are combined. May be decoded.
- FIG. 6 is a block diagram showing the non-anchor radio base station 310B according to the first embodiment.
- the non-anchor radio base station 310B includes a reception unit 313B, a transmission unit 314B, an interface 315B, and a control unit 316B.
- the receiving unit 313B receives an uplink signal from the UE 10 connected to a cell managed by the non-anchor radio base station 310B.
- the reception unit 313B receives an uplink signal via an uplink shared channel (PUSCH).
- PUSCH uplink shared channel
- the transmission unit 314B transmits a downlink signal to the UE 10 connected to the cell managed by the non-anchor radio base station 310B.
- the transmission unit 314B transmits radio resources (scheduling information) allocated by the non-anchor radio base station 310B.
- the interface 315B is an interface that communicates with other radio base stations via the backhaul network.
- the interface 315B is an X2 interface that directly connects wireless base stations.
- the interface 315B is an S1 interface that connects wireless base stations via an upper node (for example, the MME 130).
- the interface 315B transmits an uplink signal before decoding to the anchor radio base station 310A when the anchor radio base station 310A notifies that the uplink signal before decoding should be transmitted.
- a transmission unit for transmission is configured.
- the control unit 316B controls the operation of the non-anchor radio base station 310B. For example, the control unit 316B instructs the interface 315B to transmit an uplink signal before decoding.
- FIG. 7 is a sequence diagram showing operations of the mobile communication system 100 according to the first embodiment.
- step 11 the UE 10 transmits an uplink signal to the anchor radio base station 310A and the non-anchor radio base station 310B.
- the anchor radio base station 310A does not receive the uplink signal before decoding from the non-anchor radio base station 310B via the backhaul network, but decodes the uplink signal before decoding received from the UE 10. Do.
- step 13 the anchor radio base station 310A notifies the non-anchor radio base station 310B that the uplink signal before decoding should be transmitted via the backhaul network (transmission request).
- step 14 the non-anchor radio base station 310B transmits an uplink signal before decoding to the anchor radio base station 310A.
- step 15 the anchor radio base station 310A performs selective combining of the uplink signal before decoding transmitted from the UE 10 and the uplink signal before decoding received from the non-anchor radio base station 310B.
- step 16 the anchor radio base station 310A transmits the decoding result of the uplink signal to the MME 130.
- the decoding result of the uplink signal is transmitted to the MME 130.
- the embodiment is not limited to this.
- the decoding result of the uplink signal is transmitted to the RNC 220A.
- the anchor radio base station 310A when the anchor radio base station 310A fails to decode the uplink signal before decoding received from the UE 10, the anchor radio base station 310A notifies the non-anchor radio base station 310B via the backhaul network before decoding. That the uplink signal should be transmitted. Therefore, unnecessary transmission of uplink signals before decoding from the non-anchor radio base station 310B to the anchor radio base station 310A is suppressed, and an increase in load on the backhaul network is suppressed.
- the anchor radio base station 310A transmits to the non-anchor radio base station 310B the bit accuracy of the uplink signal before decoding to be transmitted via the backhaul network. To be notified.
- the non-anchor radio base station 310B transmits an uplink signal before decoding to the anchor radio base station 310A according to the bit accuracy notified from the anchor radio base station 310A.
- the bit precision indicates the granularity (hereinafter referred to as sampling granularity) for sampling the uplink signal before decoding.
- the bit accuracy is the number of bits (resolution) representing the I / Q component constituting the uplink signal before decoding.
- the bit accuracy may be represented by an index indicating the sampling granularity.
- the bit accuracy is a value that directly specifies the accuracy of the uplink signal before decoding, for example. That is, the bit accuracy is an absolute value indicating the sampling granularity.
- the bit accuracy is determined based on at least one of the reception quality of the uplink signal before decoding, the reception quality of the uplink signal after decoding, and the modulation and coding scheme of the uplink signal. .
- the reception quality of the uplink signal before decoding is the radio quality before decoding, such as SNR (Signal to Noise Ratio), SINR (Signal to Interference Noise Ratio), and the like.
- the reception quality of the uplink signal after decoding is the quality after decoding, for example, BLER (Block Error Rate).
- the modulation and coding scheme of the uplink signal is a value that affects the data transmission rate and error rate, and is referred to as MCS (Modulation and Coding Scheme).
- the bit accuracy is a value that relatively specifies the accuracy of the uplink signal before decoding, for example. That is, the bit accuracy is a relative value indicating the sampling granularity.
- the bit precision is a value indicating an increase in sampling granularity (hereinafter, UP), a value indicating maintenance of the sampling granularity (hereinafter, KEEP), and a value indicating a decrease in sampling granularity (hereinafter, DOWN).
- UP an increase in sampling granularity
- KEEP a value indicating maintenance of the sampling granularity
- DOWN a value indicating a decrease in sampling granularity
- bit accuracy is a value indicating the sampling granularity.
- bit precision is expressed in the form of an index.
- the bit precision is an absolute value and is determined based on the SNR. For example, when the SNR is “20” or more, “4” is selected as the bit accuracy. When the SNR is “10” or more and less than “20”, “8” is selected as the bit accuracy. When the SNR is greater than or equal to “0” and less than “10”, “16” is selected as the bit accuracy. Thus, the bit accuracy with a finer sampling granularity is selected as the SNR is worse.
- the bit precision is an absolute value and is determined based on the MCS. For example, when MCS is QPSK, “4” is selected as the bit accuracy. When MCS is 16QAM, “8” is selected as the bit accuracy. When MCS is 64QAM, “16” is selected as the bit accuracy. Thus, the higher the transmission rate, the more precise the bit granularity is selected.
- the bit precision is an absolute value and is determined based on BLER. For example, when BLER is “0.001” or more and less than “0.01”, “4” is selected as the bit accuracy. When BLER is “0.01” or more and less than “0.1”, “8” is selected as the bit accuracy. When BLER is “0.1” or more, “16” is selected as the bit accuracy. Thus, the bit accuracy with a finer sampling granularity is selected as the BLER is worse.
- the bit precision is a relative value and is determined based on the previous decoding result. For example, when the previous decoding result is NG, that is, when decoding of the previous uplink signal fails, UP is selected as the bit accuracy. On the other hand, when the previous decoding result is OK, that is, when the previous uplink signal has been successfully decoded, KEEP or DOWN is selected as the bit accuracy.
- FIG. 12 is a sequence diagram showing operations of the mobile communication system 100 according to the first modification.
- step 21 the UE 10 transmits an uplink signal to the anchor radio base station 310A and the non-anchor radio base station 310B.
- the anchor radio base station 310A does not receive the uplink signal before decoding from the non-anchor radio base station 310B via the backhaul network, but decodes the uplink signal before decoding received from the UE 10. Do.
- step 23 the anchor radio base station 310A determines the bit accuracy of the uplink signal before decoding to be transmitted via the backhaul network.
- step 24 the anchor radio base station 310A transmits the uplink signal before decoding to the non-anchor radio base station 310B via the backhaul network (transmission request), and transmits the backhaul network.
- the bit accuracy of the uplink signal before decoding to be transmitted is notified.
- step 25 the non-anchor radio base station 310B transmits an uplink signal before decoding to the anchor radio base station 310A according to the bit accuracy notified from the anchor radio base station 310A.
- step 26 the anchor radio base station 310A performs selective combining of the uplink signal before decoding transmitted from the UE 10 and the uplink signal before decoding received from the non-anchor radio base station 310B.
- step 27 the anchor radio base station 310A transmits the decoding result of the uplink signal to the MME 130.
- the decoding result of the uplink signal is transmitted to the MME 130.
- the embodiment is not limited to this.
- the decoding result of the uplink signal is transmitted to the RNC 220A.
- the non-anchor radio base station 310B transmits an uplink signal before decoding to the anchor radio base station 310A according to the bit accuracy notified from the anchor radio base station 310A.
- the uplink signal before decoding is transmitted with appropriate bit accuracy. Therefore, an increase in the load on the backhaul network is suppressed.
- the anchor radio base station 310A (interface 315A) receives the uplink signal received by the non-anchor radio base station 310B from the non-anchor radio base station 310B that satisfies a predetermined quality. Then, it notifies that the uplink signal before decoding should be transmitted via the backhaul network.
- FIG. 13 is a sequence diagram showing an operation of the mobile communication system 100 according to the second modification.
- step 31 the UE 10 transmits an uplink signal to the anchor radio base station 310A and the non-anchor radio base station 310B.
- the anchor radio base station 310A does not receive the uplink signal before decoding from the non-anchor radio base station 310B via the backhaul network, but decodes the uplink signal before decoding received from the UE 10. Do.
- each non-anchor radio base station 310B measures the reception quality of the uplink signal.
- each non-anchor radio base station 310B notifies the reception quality of the uplink signal to the anchor radio base station 310A.
- the anchor radio base station 310A determines the non-anchor radio base station 310B to which the uplink signal before decoding is to be transmitted via the backhaul network. Specifically, the anchor radio base station 310A determines a non-anchor radio base station whose reception quality notified in step 34 satisfies a predetermined quality as a non-anchor radio base station 310B to transmit an uplink signal before decoding. To do.
- the anchor radio base station 310 ⁇ / b> A backhauls the non-anchor radio base station 310 ⁇ / b> B with respect to the non-anchor radio base station 310 ⁇ / b> B whose reception quality (for example, SNR or SINR) of the uplink signal received by the non-anchor radio base station 310 ⁇ / b> B satisfies a predetermined quality. Notifying that the uplink signal before decoding should be transmitted via the network (transmission request).
- reception quality for example, SNR or SINR
- step 37 the non-anchor radio base station 310B notified from the anchor radio base station 310A that the uplink signal before decoding should be transmitted, transmits the uplink signal before decoding to the anchor radio base station 310A. To do.
- the anchor radio base station 310A performs selective combining of the uplink signal before decoding transmitted from the UE 10 and the uplink signal before decoding received from the non-anchor radio base station 310B.
- step 39 the anchor radio base station 310A transmits the decoding result of the uplink signal to the MME 130.
- the decoding result of the uplink signal is transmitted to the MME 130.
- the embodiment is not limited to this.
- the decoding result of the uplink signal is transmitted to the RNC 220A.
- the anchor radio base station 310A performs decoding via the backhaul network with respect to the non-anchor radio base station 310B in which the reception quality of the uplink signal received by the non-anchor radio base station 310B satisfies the predetermined quality. Notify that the previous uplink signal should be transmitted. Therefore, unnecessary transmission of uplink signals before decoding from the non-anchor radio base station 310B to the anchor radio base station 310A is suppressed, and an increase in load on the backhaul network is suppressed.
- the non-anchor radio base station 310B (interface 315B) is notified from the anchor radio base station 310A that the uplink signal before decoding should be transmitted, and the non-anchor radio base station
- the uplink signal before decoding is transmitted to the anchor radio base station 310A via the backhaul network.
- the non-anchor radio base station 310B (interface 315B), when the reception quality of the uplink signal received by the non-anchor radio base station 310B does not satisfy the predetermined quality, On the other hand, the uplink signal before decoding is not transmitted.
- the predetermined quality may be notified from the anchor radio base station 310A (interface 315A) to the non-anchor radio base station 310B before receiving an uplink signal from the UE 10.
- the predetermined quality may be determined in advance.
- FIG. 14 is a sequence diagram showing operations of the mobile communication system 100 according to the third modification.
- step 41 the UE 10 transmits an uplink signal to the anchor radio base station 310A and the non-anchor radio base station 310B.
- the anchor radio base station 310 ⁇ / b> A does not receive the uplink signal before decoding from the non-anchor radio base station 310 ⁇ / b> B via the backhaul network, but decodes the uplink signal before decoding received from the UE 10. Do.
- step 43 the anchor radio base station 310A notifies the non-anchor radio base station 310B that the uplink signal before decoding should be transmitted via the backhaul network (transmission request).
- each non-anchor radio base station 310B measures the reception quality of the uplink signal.
- the non-anchor radio base station 310B that satisfies the predetermined quality of the reception quality (for example, SNR or SINR) of the uplink signal received by the non-anchor radio base station 310B is backhauled to the anchor radio base station 310A.
- -Transmit the uplink signal before decoding via the network That is, when the non-anchor radio base station 310B is notified that the uplink signal before decoding should be transmitted (transmission request), and the reception quality (eg, SNR or SINR) of the uplink signal satisfies the predetermined quality Then, the uplink signal before decoding is transmitted.
- the reception quality eg, SNR or SINR
- step 46 the anchor radio base station 310A performs selective combining of the uplink signal before decoding transmitted from the UE 10 and the uplink signal before decoding received from the non-anchor radio base station 310B.
- Step 47 the anchor radio base station 310A transmits the decoding result of the uplink signal to the MME 130.
- the decoding result of the uplink signal is transmitted to the MME 130.
- the embodiment is not limited to this.
- the decoding result of the uplink signal is transmitted to the RNC 220A.
- the non-anchor radio base station 310B transmits a backhaul network to the anchor radio base station 310A when the reception quality of the uplink signal received by the non-anchor radio base station 310B satisfies a predetermined quality. Via the uplink signal before decoding. Therefore, unnecessary transmission of uplink signals before decoding from the non-anchor radio base station 310B to the anchor radio base station 310A is suppressed, and an increase in load on the backhaul network is suppressed.
- the uplink signal before decoding transmitted from the non-anchor radio base station 310B to the anchor radio base station 310A constitutes an uplink signal received by the non-anchor radio base station 310B. It should be noted that the result (bit string) obtained by sampling the I / Q component is included.
- the uplink signal before decoding is preferably transmitted for each subframe from the non-anchor radio base station 310B to the anchor radio base station 310A.
- the uplink signal before decoding preferably includes a subframe number and an identifier for identifying the UE 10 in addition to the result (bit string) obtained by sampling the I / Q component.
- the uplink signal before decoding includes the type of scheme (for example, legacy scheme or carrier aggregation scheme) in which the UE 10 transmits the uplink signal, in addition to these pieces of information.
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Abstract
Description
実施形態に係る移動通信システムは、無線端末から送信される上りリンク信号を複数の無線基地局で協調して受信するシステムである。前記複数の無線基地局は、1つのアンカー無線基地局と、前記アンカー無線基地局以外の非アンカー無線基地局とを含む。前記アンカー無線基地局は、前記非アンカー無線基地局からバックホール・ネットワークを介してデコード前の上りリンク信号を受信せずに、前記無線端末から受信するデコード前の上りリンク信号のデコードを行う制御部と、前記無線端末から受信するデコード前の上りリンク信号のデコードに失敗した場合に、前記非アンカー無線基地局に対して、前記バックホール・ネットワークを介して前記デコード前の上りリンク信号を送信すべき旨を通知する通知部とを備える。前記非アンカー無線基地局は、前記デコード前の上りリンク信号を送信すべき旨が前記アンカー無線基地局から通知された場合に、前記アンカー無線基地局に対して、前記デコード前の上りリンク信号を送信する送信部を備える。
(移動通信システム)
以下において、第1実施形態に係る移動通信システムについて説明する。図1は、第1実施形態に係る移動通信システム100を示す図である。
以下において、第1通信システムにおける無線フレームについて説明する。図2は、第1通信システムにおける無線フレームを示す図である。
以下において、第1通信システムにおける無線リソースについて説明する。図3は、第1通信システムにおける無線リソースを示す図である。
以下において、第1実施形態に係る適用シーンについて説明する。図4は、第1実施形態に係る適用シーンを説明するための図である。図4では、1つのアンカー無線基地局310A及び複数の非アンカー無線基地局310Bが無線基地局として設けられるケースについて例示する。アンカー無線基地局310A及び非アンカー無線基地局310Bは、UE10から送信される上りリンク信号を協調して受信する無線基地局群(CoMPセット)を構成する。
以下において、第1実施形態に係るアンカー無線基地局について説明する。図5は、第1実施形態に係るアンカー無線基地局310Aを示すブロック図である。
以下において、第1実施形態に係る非アンカー無線基地局について説明する。図6は、第1実施形態に係る非アンカー無線基地局310Bを示すブロック図である。
以下において、第1実施形態に係る移動通信システムの動作について説明する。図7は、第1実施形態に係る移動通信システム100の動作を示すシーケンス図である。
第1実施形態では、アンカー無線基地局310Aは、UE10から受信するデコード前の上りリンク信号のデコードに失敗した場合に、非アンカー無線基地局310Bに対して、バックホール・ネットワークを介してデコード前の上りリンク信号を送信すべき旨を通知する。従って、非アンカー無線基地局310Bからアンカー無線基地局310Aに対する不要なデコード前の上りリンク信号の送信が抑制され、バックホール・ネットワークの負荷増大が抑制される。
以下において、第1実施形態の変更例1について説明する。以下においては、第1実施形態に対する相違点について主として説明する。
以下において、変更例1に係るビット精度について説明する。図8~図11は、変更例1に係るビット精度を説明するための図である。ビット精度は、サンプリング粒度を示す値である。ここでは、ビット精度は、インデックスの形式で表されている。ここでは、ビット精度の値が大きい程、サンプリング粒度が細かいことに留意すべきである。
以下において、変更例1に係る移動通信システムの動作について説明する。図12は、変更例1に係る移動通信システム100の動作を示すシーケンス図である。
変更例1では、非アンカー無線基地局310Bは、アンカー無線基地局310Aから通知されるビット精度に応じて、アンカー無線基地局310Aに対して、デコード前の上りリンク信号を送信する。言い換えると、デコード前の上りリンク信号が適切なビット精度で送信される。従って、バックホール・ネットワークの負荷増大が抑制される。
以下において、第1実施形態の変更例2について説明する。以下においては、第1実施形態に対する相違点について主として説明する。
以下において、変更例2に係る移動通信システムの動作について説明する。図13は、変更例2に係る移動通信システム100の動作を示すシーケンス図である。
変更例2では、アンカー無線基地局310Aは、非アンカー無線基地局310Bが受信する上りリンク信号の受信品質が所定品質を満たす非アンカー無線基地局310Bに対して、バックホール・ネットワークを介してデコード前の上りリンク信号を送信すべき旨を通知する。従って、非アンカー無線基地局310Bからアンカー無線基地局310Aに対する不要なデコード前の上りリンク信号の送信が抑制され、バックホール・ネットワークの負荷増大が抑制される。
以下において、第1実施形態の変更例3について説明する。以下においては、第1実施形態に対する相違点について主として説明する。
以下において、変更例3に係る移動通信システムの動作について説明する。図14は、変更例3に係る移動通信システム100の動作を示すシーケンス図である。
変更例3では、非アンカー無線基地局310Bは、非アンカー無線基地局310Bが受信する上りリンク信号の受信品質が所定品質を満たす場合に、アンカー無線基地局310Aに対して、バックホール・ネットワークを介してデコード前の上りリンク信号を送信する。従って、非アンカー無線基地局310Bからアンカー無線基地局310Aに対する不要なデコード前の上りリンク信号の送信が抑制され、バックホール・ネットワークの負荷増大が抑制される。
本発明は上述した実施形態によって説明したが、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ろう。
Claims (8)
- 無線端末から送信される上りリンク信号を複数の無線基地局で協調して受信する移動通信システムであって、
前記複数の無線基地局は、1つのアンカー無線基地局と、前記アンカー無線基地局以外の非アンカー無線基地局とを含み、
前記アンカー無線基地局は、
前記非アンカー無線基地局からバックホール・ネットワークを介してデコード前の上りリンク信号を受信せずに、前記無線端末から受信するデコード前の上りリンク信号のデコードを行う制御部と、
前記無線端末から受信するデコード前の上りリンク信号のデコードに失敗した場合に、前記非アンカー無線基地局に対して、前記バックホール・ネットワークを介して前記デコード前の上りリンク信号を送信すべき旨を通知する通知部とを備え、
前記非アンカー無線基地局は、
前記デコード前の上りリンク信号を送信すべき旨が前記アンカー無線基地局から通知された場合に、前記アンカー無線基地局に対して、前記デコード前の上りリンク信号を送信する送信部を備えることを特徴とする移動通信システム。 - 前記通知部は、前記バックホール・ネットワークを介して送信すべき前記デコード前の上りリンク信号のビット精度を通知することを特徴とする請求項1に記載の移動通信システム。
- 前記ビット精度は、前記デコード前の上りリンク信号の精度を直接的に指定する値であることを特徴とする請求項2に記載の移動通信システム。
- 前記ビット精度は、デコード前の上りリンク信号の受信品質、デコード後の上りリンク信号の受信品質、及び、上りリンク信号の変調符号化方式の少なくとも1つに基づいて設定されることを特徴とする請求項3に記載の移動通信システム。
- 前記ビット精度は、前記デコード前の上りリンク信号の精度を相対的に指定する値であることを特徴とする請求項2に記載の移動通信システム。
- 前記通知部は、前記非アンカー無線基地局が受信する上りリンク信号の受信品質が所定品質を満たす非アンカー無線基地局に対して、前記バックホール・ネットワークを介して前記デコード前の上りリンク信号を送信すべき旨を通知することを特徴とする請求項1に記載の移動通信システム。
- 前記送信部は、前記デコード前の上りリンク信号を送信すべき旨が前記アンカー無線基地局から通知され、かつ、前記非アンカー無線基地局が受信する上りリンク信号の受信品質が所定品質を満たす場合に、前記アンカー無線基地局に対して、バックホール・ネットワークを介してデコード前の上りリンク信号を送信することを特徴とする請求項1に記載の移動通信システム。
- 無線端末から送信される上りリンク信号を複数の無線基地局で協調して受信する移動通信方法であって、
前記複数の無線基地局は、1つのアンカー無線基地局と、前記アンカー無線基地局以外の非アンカー無線基地局とを含み、
前記アンカー無線基地局において、前記非アンカー無線基地局からバックホール・ネットワークを介してデコード前の上りリンク信号を受信せずに、前記無線端末から受信するデコード前の上りリンク信号のデコードを行うステップと、
前記アンカー無線基地局において、前記無線端末から受信するデコード前の上りリンク信号のデコードに失敗した場合に、前記非アンカー無線基地局に対して、前記バックホール・ネットワークを介して前記デコード前の上りリンク信号を送信すべき旨を通知するステップと、
前記デコード前の上りリンク信号を送信すべき旨が前記アンカー無線基地局から通知された場合に、前記非アンカー無線基地局から前記アンカー無線基地局に対して、前記デコード前の上りリンク信号を送信するステップとを備えることを特徴とする移動通信方法。
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