WO2022168143A1 - 無線通信装置及び無線通信方法 - Google Patents
無線通信装置及び無線通信方法 Download PDFInfo
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- WO2022168143A1 WO2022168143A1 PCT/JP2021/003665 JP2021003665W WO2022168143A1 WO 2022168143 A1 WO2022168143 A1 WO 2022168143A1 JP 2021003665 W JP2021003665 W JP 2021003665W WO 2022168143 A1 WO2022168143 A1 WO 2022168143A1
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- 238000004891 communication Methods 0.000 title claims abstract description 70
- 238000000034 method Methods 0.000 title claims description 22
- 230000005540 biological transmission Effects 0.000 claims abstract description 7
- 238000012545 processing Methods 0.000 claims description 17
- 238000010586 diagram Methods 0.000 description 8
- 238000005259 measurement Methods 0.000 description 8
- 239000000284 extract Substances 0.000 description 4
- 238000007619 statistical method Methods 0.000 description 3
- 230000001747 exhibiting effect Effects 0.000 description 2
- 238000010295 mobile communication Methods 0.000 description 2
- 239000013307 optical fiber Substances 0.000 description 2
- 230000003247 decreasing effect Effects 0.000 description 1
- 230000001934 delay Effects 0.000 description 1
- 238000013461 design Methods 0.000 description 1
- 239000000835 fiber Substances 0.000 description 1
- 230000010365 information processing Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
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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
- H04B7/0617—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 for beam forming
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B17/00—Monitoring; Testing
- H04B17/30—Monitoring; Testing of propagation channels
- H04B17/373—Predicting channel quality or other radio frequency [RF] parameters
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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
- H04B7/0452—Multi-user 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
- H04B7/06—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the transmitting station
- H04B7/0686—Hybrid systems, i.e. switching and simultaneous transmission
- H04B7/0695—Hybrid systems, i.e. switching and simultaneous transmission using beam selection
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04W—WIRELESS COMMUNICATION NETWORKS
- H04W16/00—Network planning, e.g. coverage or traffic planning tools; Network deployment, e.g. resource partitioning or cells structures
- H04W16/24—Cell structures
- H04W16/28—Cell structures using beam steering
Definitions
- the present invention relates to a wireless communication device and a wireless communication method.
- radio waves in the high frequency band are used for communication.
- Future wireless systems for example, sixth-generation mobile communication systems
- Non-Patent Document 1 a wireless communication system (distributed antenna system) that communicates using a plurality of distributed antennas has been studied.
- Distributed antenna systems use multiple distributed antennas to support Single User MIMO (Single User - Multi-Input Multi-Output: SU-MIMO) and Multi-User MIMO (Multi User - Multi-Input Multi-Output: MU -MIMO) and These allow the distributed antenna system to improve communication capacity.
- Single User MIMO Single User - Multi-Input Multi-Output: SU-MIMO
- Multi-User MIMO Multi User - Multi-Input Multi-Output: MU -MIMO
- Patent Document 1 in a wireless communication system including a base station (wireless communication device) using multi-user MIMO and a plurality of mobile stations (user terminals), based on each channel estimation value between the base station and each mobile station, Accordingly, a base station has been proposed that determines the number and parameters of streams sent to each mobile station.
- a base station assigns the number of streams transmitted from an antenna to a mobile station to each mobile station by applying the Greedy method or the like to each channel estimation value. This makes it possible to improve the communication capacity.
- One aspect of the present invention is a terminal selection unit that selects one or more user terminals, and a prediction that derives a predicted value of the interference amount of a group of streams transmitted from a plurality of antennas for the selected one or more user terminals a collection unit that collects received power values of beams of streams included in the stream group from the one or more selected user terminals when the predicted value of the amount of interference is less than a threshold, and the received power an antenna selection unit that selects the plurality of streams in descending order of values and selects the plurality of antennas associated with the plurality of selected streams; and a transmitter that transmits by beamforming using the antenna.
- One aspect of the present invention is a wireless communication method executed by a wireless communication device, comprising: a terminal selection step of selecting one or more user terminals; a prediction step of deriving a predicted value of the amount of interference for a group of streams in the stream group, and if the predicted value of the amount of interference is less than a threshold, the received power value of the beam of the stream included in the stream group is set to the selected one or more an antenna selection step of selecting a plurality of the streams in order of decreasing received power value, and selecting a plurality of the antennas associated with the selected plurality of the streams; and a transmission step of transmitting the selected plurality of streams by beamforming using the selected plurality of antennas.
- FIG. 1 is a diagram showing a configuration example of a wireless communication system in an embodiment
- FIG. FIG. 4 is a diagram showing an example of adding a stream to a group of spatially multiplexed streams in the embodiment
- 4 is a sequence diagram showing an operation example of the wireless communication system in the embodiment
- FIG. 4 is a flowchart showing an operation example of the wireless communication system in the embodiment
- 9 is a flowchart showing an example of operation of a wireless communication system in a modified example of the embodiment
- 1 is a diagram illustrating an example hardware configuration of a wireless communication device in an embodiment
- a wireless communication system is a system (distributed antenna system) that wirelessly communicates a stream (data sequence) using at least some of all distributed antennas.
- a wireless communication system one stream per antenna is transmitted to a user terminal using one beam per antenna. Therefore, when multiple streams (stream groups) are allocated to a user terminal, the multiple allocated streams (beams) are transmitted from multiple antennas toward the user terminal.
- the base station of the wireless communication system selects multiple antennas for transmitting multiple assigned streams from among all the distributed antennas.
- the base station derives a predicted value of the amount of interference between streams transmitted from the selected multiple antennas using a predetermined statistical method based on the combination of the selected multiple antennas. Also, the base station determines whether the derived prediction value is less than a predetermined threshold before transmitting the stream.
- the base station When it is determined that the predicted value of the amount of interference between streams is less than a predetermined threshold, the base station generates beams for each distributed antenna so that each user terminal can measure the received power value of the beams of the streams. Run a search.
- the base station uses each antenna to transmit a power measurement signal beam to each user terminal in the communication area.
- Each user terminal feeds back the maximum received power value of the beam of the power measurement signal transmitted from each antenna to the base station.
- the base station collects the maximum received power value of the beam of the transmitted power measurement signal from each user terminal in the communication area. That is, the base station collects, from each user terminal in the communication area, the maximum received power value for each antenna that has transmitted the beam of the signal for power measurement.
- the received power value of the beam of the power measurement signal transmitted from the antenna corresponds to the received power value of the beam of the stream transmitted from the same antenna. Note that the received power value is a simpler index than the channel estimation value (an index that does not require a high processing load).
- the base station allocates one or more downlink streams to one or more selected user terminals within the range of the number of streams that can be simultaneously transmitted by the base station in response to an allocation request transmitted from a higher-level device.
- the base station allocates the number of streams to one or more selected user terminals based on the collected received power values.
- the base station may assign the number of streams to one or more selected user terminals based on the collected received power values.
- the base station selects multiple antennas from among all distributed antennas, giving priority to antennas with a high signal-to-noise ratio of the stream.
- all distributed antennas may be selected, or a part of all distributed antennas may be selected.
- the base station uses high-frequency band radio waves (radio signals) transmitted from a plurality of selected antennas. and transmit the streams to one or more user terminals.
- the wireless communication system performs beamforming to reduce the amount of interference between streams.
- FIG. 1 is a diagram showing a configuration example of a radio communication system 1.
- the wireless communication system 1 is a system (distributed antenna system) that wirelessly communicates a stream using at least some of all distributed antennas.
- a wireless communication system 1 includes a host device 2 , a base station 3 , multiple antennas 4 , and one or more user terminals 5 .
- a plurality of antennas 4 protrude from the base station 3 and are distributed in the communication area.
- the base station 3 and each antenna 4 are connected using, for example, optical fibers or coaxial cables.
- Optical fibers may transmit optical signals between the base station 3 and each antenna 4 using analog RoF (Radio-over-Fiber).
- the radio communication system 1 comprises 16 antennas 4 as an example.
- Antenna 4 comprises a plurality of antenna elements.
- the user terminal 5 is provided with one or more antenna elements.
- the host device 2 is an information processing device, such as a server device. Host device 2 transmits stream (data series) candidates transmitted from antenna 4 to base station 3 .
- the base station 3 centrally controls the operation of each distributed antenna 4 .
- the base station 3 selects a plurality of antennas 4 from among all the distributed antennas 4 .
- the base station 3 uses a plurality of selected antennas 4 to transmit spatially multiplexed stream groups 8 to one or more user terminals 5 .
- the base station 3 uses a plurality of antenna elements provided in the antenna 4 to perform beamforming. This ensures gain in the high frequency band.
- Both the base station 3 and the user terminal 5 may perform beamforming. Also, the host device 2 may acquire a plurality of streams from the base station 3 by uplink transmission.
- the base station 3 performs at least one of single-user MIMO and multi-user MIMO.
- a plurality of antennas 4 simultaneously transmit a group of spatially multiplexed streams 8 (a plurality of streams) to a plurality of user terminals 5 .
- the base station 3 performs multi-user MIMO on the downlink.
- multiple user terminals 5 may simultaneously transmit spatially multiplexed streams to multiple antennas 4 . In this way the base station 3 may perform multi-user MIMO for the uplink.
- a plurality of antennas 4 simultaneously transmit a group of spatially multiplexed streams 9 (a plurality of streams) to a single user terminal 5 .
- antenna 4-1 uses beam 6-1 to transmit stream 7-1 towards user terminal 5-1.
- Antenna 4-3 uses beam 6-3 to transmit stream 7-3 towards user terminal 5-1.
- the base station 3 implements single-user MIMO for the downlink.
- a single user terminal 5 may simultaneously transmit spatially multiplexed streams to multiple antennas 4 . In this way the base station 3 may perform single-user MIMO for the uplink.
- a stream group 8 is a multi-user MIMO stream group.
- the upper limit of the number of streams 7 that can be simultaneously communicated in multiuser MIMO is determined based on a parameter representing the maximum number of layers in multiuser MIMO.
- a stream group 9 is a single-user MIMO stream group. Note that the upper limit of the number of streams 7 that can be simultaneously communicated in single-user MIMO is determined based on a parameter representing the maximum number of layers in single-user MIMO.
- the base station 3 includes a terminal selection unit 30, a prediction unit 31, a collection unit 32, an antenna selection unit 33, and a communication unit 34 (transmitting unit, receiving unit).
- the terminal selection unit 30 acquires a plurality of stream identifiers from the host device 2 as a downlink stream allocation request.
- the terminal selection unit 30 manages stream candidates to be assigned to the user terminal 5 with respect to the acquired stream identifiers. That is, the terminal selection unit 30 selects one or more user terminals 5 from a plurality of user terminals 5 in the communication area based on the stream identifier.
- the terminal selection unit 30 selects the user terminal 5 based on a predetermined index such as a rank indicator (RI) and a predetermined scheduling process.
- a predetermined index such as a rank indicator (RI) and a predetermined scheduling process.
- the terminal selection unit 30 may select the user terminal 5 based on proportional fairness (PF) and predetermined scheduling processing.
- PF proportional fairness
- the terminal selection unit 30 may select the user terminals 5 in descending order of received power of the stream transmitted from the antenna 4 .
- the terminal selection unit 30 may select user terminals 5 having similar reception power values of beams of streams transmitted from the antennas 4 .
- the terminal selection unit 30 may select a plurality of user terminals 5 based on the positional relationship between the user terminals 5 so that the amount of interference between streams between the user terminals 5 is reduced. For example, the terminal selection unit 30 may select user terminals 5 separated from each other by a predetermined distance or more so that the amount of interference between streams between the user terminals 5 is reduced.
- the terminal selection unit 30 may select user terminals 5 whose number is equal to or greater than the maximum number of layers of multi-user MIMO. For example, the terminal selection unit 30 may select user terminals 5 whose number is less than the maximum number of layers of multi-user MIMO.
- the prediction unit 31 acquires data representing one or more selected user terminals 5 (for example, terminal identifiers) from the terminal selection unit 30 .
- the prediction unit 31 derives a prediction value of the amount of interference between streams transmitted from the plurality of antennas 4 for one or more selected user terminals 5 .
- the prediction unit 31 derives, for a single selected user terminal 5 , a predicted value of the amount of interference between streams of that user terminal 5 .
- the prediction unit 31 derives a prediction value of the amount of interference between streams of the plurality of user terminals 5 selected for the plurality of user terminals 5 .
- the prediction unit 31 determines whether or not the predicted value of the interference amount of the stream group is less than a predetermined threshold. Note that when it is determined that the predicted value of the interference amount of the stream group is equal to or greater than the predetermined threshold, the terminal selection unit 30 continues until it is determined that the predicted value of the interference amount of the stream group is less than the predetermined threshold.
- the process of selecting the user terminal 5 may be redone.
- the prediction unit 31 uses a predetermined statistical method based on the combination of multiple antennas 4 and multiple transmitted streams (beams) to derive a predicted value of the amount of interference between streams.
- the prediction unit 31 uses a predetermined statistical method based on the positional relationship of the plurality of antennas 4 and the beam width corresponding to the number of antenna elements for each antenna 4 to derive a predicted value of the amount of interference between streams. good.
- the terminal selection unit 30 may select the user terminal 5 based on these derived prediction values so that the amount of interference between streams is reduced.
- the collection unit 32 collects power measurement signals transmitted from each antenna 4 that may transmit a stream to each selected user terminal 5.
- the received power value of the beam is collected by feedback from each selected user terminal 5 or the like.
- the antenna 4 that may transmit the stream is the antenna 4 pre-associated with the identifier of the acquired stream.
- the received power value of the beam of the power measurement signal transmitted from the antenna 4 corresponds to the received power value of the beam of the stream transmitted from the same antenna 4 .
- the antenna selection unit 33 selects a plurality of streams from the stream candidates in descending order of received power value of the stream beam. That is, the antenna selection unit 33 selects the stream that indicates the maximum received power value based on the correspondence between the antenna 4 and the stream 7 from among the stream candidates determined by the identifiers of the multiple streams acquired from the host device 2. choose with priority.
- the antenna selection unit 33 selects the antenna 4 associated with the selected stream 7.
- the antenna selection unit 33 avoids redundant selection of the antenna 4 (resource).
- the antenna selection unit 33 excludes the later selected stream 7 from candidates for the stream 7 to be added to the stream group 8 to be spatially multiplexed.
- the antenna selection unit 33 transmits the streams 7 until the number of streams 7 in the spatially multiplexed stream group 8 reaches the maximum value of the number of layers of multi-user MIMO, or until there are no remaining stream candidates. to select. In this manner, the antenna selector 33 determines allocation (distribution) of the stream 7 to each user terminal 5 .
- the terminal selection unit 30 selects the user terminal 5 may be additionally selected, and the antenna selection unit 33 may add stream candidates addressed to the user terminal 5 to the stream group 8 .
- the communication unit 34 (transmitting unit, receiving unit) requests the higher-level device 2 to transmit the plurality of selected streams downstream.
- the communication unit 34 acquires the selected multiple streams from the host device 2 .
- the communication unit 34 transmits the selected streams by beamforming using the selected antennas 4 .
- FIG. 2 is a diagram showing an example of addition of a stream 7 to a spatially multiplexed stream group 8 (an example of allocation of streams to user terminals).
- the selected user terminals 5 are, for example, a user terminal 5-1, a user terminal 5-2, and a user terminal 5-3.
- the antenna selection unit 33 extracts the numbers (antenna numbers) of the antennas 4 that have the possibility of transmitting a stream to each user terminal 5 from among all the numbers of the distributed antennas 4 by the search process. . That is, the antenna selection unit 33 extracts the number of the antenna 4 associated with the stream candidate from among all the numbers of the antennas 4 distributed.
- the received power value and the antenna number are associated with each other based on the result of a beam search performed in advance using the beam of the power measurement signal transmitted from each antenna 4.
- stream candidates and antenna numbers are associated with each other, for example, based on the positional relationship between the user terminal 5 serving as the destination of the stream and the antenna 4 .
- stream candidates and received power values are associated with each other based on the antenna numbers.
- the antenna selection unit 33 selects, for example, an antenna 4-3 associated with the stream 7-3, an antenna 4-7 associated with the stream 7-7, and an antenna 4-7 associated with the stream 7-5. and the antenna 4-1 associated with the stream 7-1 are extracted from the plurality of distributed antennas 4.
- the antenna selection unit 33 selects, for example, an antenna 4-6 associated with the stream 7-6, an antenna 4-5 associated with the stream 7-5, and an antenna 4-5 associated with the stream 7-7. and the antenna 4-4 associated with the stream 7-4 are extracted from the plurality of distributed antennas 4.
- the antenna selection unit 33 selects, for example, an antenna 4-12 associated with the stream 7-12, an antenna 4-9 associated with the stream 7-9, and an antenna 4-9 associated with the stream 7-5. and the antenna 4-8 associated with the stream 7-8 are extracted from the plurality of distributed antennas 4.
- the antenna selection unit 33 extracts the received power value of each selected user terminal 5 from among multiple received power values collected from multiple user terminals 5 .
- the antenna selection unit 33 extracts the stream reception power values for four or less stream candidates for each user terminal 5 .
- the maximum number of layers for single-user MIMO is 4. Therefore, the number of stream candidates is four for each user terminal 5 . Also, the maximum number of layers for multi-user MIMO is eight. Therefore, the antenna selection unit 33 adds eight or fewer streams selected from the stream candidates to the stream group 8 .
- the antenna selection unit 33 adds stream candidates to the spatially multiplexed stream group 8 in descending order of associated received power values. Here, if there are a plurality of stream candidates indicating the same received power value, the antenna selection unit 33 may randomly select a stream from among those stream candidates. Further, the antenna selection unit 33 may preferentially select stream candidates for the user terminal 5 to which the number of allocated streams 7 is small from among those stream candidates.
- the antenna selection unit 33 adds the stream 7-6 exhibiting the highest received power value "-73 dB" among the stream candidates to the stream group 8 to be spatially multiplexed. Further, the antenna selection unit 33 excludes the added stream 7-6 from stream candidates.
- the antenna selection unit 33 adds the stream 7-3 exhibiting the second largest received power value "-74 dB" among the stream candidates to the stream group 8 to be spatially multiplexed.
- the antenna selection unit 33 adds the stream 7-5 having the third largest received power value of “ ⁇ 75 dB” among the stream candidates to the stream group 8 to be spatially multiplexed.
- the antenna selection unit 33 adds the stream 7-7 having the fourth largest received power value of “ ⁇ 76 dB” among the stream candidates to the stream group 8 to be spatially multiplexed.
- the antenna selection unit 33 selects multiple antennas 4 for transmitting the multiple selected streams 7 from among all the antennas 4 in the communication area so as not to overlap. For example, the antenna selection unit 33 does not add the stream 7-7 having the fifth largest received power value of “ ⁇ 77 dB” among the stream candidates to the stream group 8 to be spatially multiplexed. This is because the antenna 4-7 associated with the stream 7-7 indicating the fifth largest received power value "-77 dB” is the stream indicating the fourth largest received power value "-76 dB" among stream candidates. This is because the antenna 4-7 associated with 7-7 has already been selected. When a stream candidate associated with the selected antenna 4 is selected, the antenna selection unit 33 does not add the stream candidate to the stream group 8, but excludes it from addition targets to the stream group 8. do.
- FIG. 3 is a sequence diagram showing an operation example of the wireless communication system 1.
- the host device 2 transmits the identifier of the stream addressed to the user terminal 5-n (n is an integer equal to or greater than 1) to the base station 3 as a stream allocation request (step S101).
- the base station 3 selects one or more user terminals 5-n to which the stream is assigned based on the stream identifier (step S102).
- the base station 3 derives a predicted value of the amount of interference between streams for one or more selected user terminals 5-n (step S103).
- the base station 3 requests one or more selected user terminals 5-n to transmit the maximum received power value.
- Each user terminal 5-n transmits the received power value of the beam transmitted from each antenna 4 to the base station 3 (step S104).
- the base station 3 collects the maximum received power value of the beam transmitted from each antenna 4 from each user terminal 5-n (step S105).
- the base station 3 searches for the antenna 4 associated with the candidate for the stream 7 to be spatially multiplexed (step S106).
- the base station 3 gives priority to a stream with a large received power value, and selects multiple antennas 4 associated with multiple streams 7 (step S107).
- the base station 3 requests transmission of multiple streams (step S108).
- the host device 2 acquires transmission requests for a plurality of streams (step S109).
- the host device 2 transmits the requested multiple streams to the base station 3 as multiple spatially multiplexed streams (step S110).
- the base station 3 acquires a plurality of spatially multiplexed streams (step S111).
- the base station 3 uses the selected multiple antennas 4 to transmit the spatially multiplexed stream group (multiple streams 7) to each user terminal 5-n (step S112).
- Each user terminal 5-n acquires the stream 7 addressed to itself from the antenna 4 associated with the stream 7 (step S113).
- the user terminal 5-n may transmit the uplink stream to the antenna 4 associated with the uplink stream (step S114).
- the base station 3 acquires its uplink streams using selected antennas 4 .
- the base station 3 transmits the uplink stream to the host device 2 (step S115).
- the host device 2 acquires the uplink stream from the base station 3 (step S116).
- FIG. 4 is a flowchart showing an operation example of the wireless communication system 1 (a method of allocating streams to each user terminal 5).
- the terminal selection unit 30 selects one or more user terminals 5 from a plurality of user terminals 5 in the communication area (step S201).
- the prediction unit 31 derives a prediction value of the amount of interference between streams transmitted from the plurality of antennas 4 for one or more selected user terminals 5 .
- the collection unit 32 determines whether or not the predicted value of the interference amount of the stream group is less than a predetermined threshold (Step S202a).
- step S202a: NO the collection unit 32 returns the process to step S201.
- step S202a: YES the collection unit 32 selects the The received power values of the selected beams are collected from one or more selected user terminals 5 (step S203).
- the antenna selection unit 33 searches for the antenna 4 associated with the candidate for the stream 7 to be spatially multiplexed (step S204).
- the antenna selection unit 33 selects the stream 7 from the candidates for the spatially multiplexed stream 7 in descending order of the received power value (step S205).
- the antenna selection unit 33 determines whether or not the antenna 4-m associated with the selected stream 7-m (m is an integer equal to or greater than 1) has already been selected. That is, the antenna selection unit 33 determines whether or not the antenna 4-m associated with the selected stream 7-m is assigned for transmission of another stream (step S206).
- the antenna selection unit 33 selects the antenna 4-m associated with the selected stream 7-m.
- the selected antenna 4-m is selected as the antenna 4 for beam forming (step S207).
- the antenna selector 33 adds the selected stream 7-m to the stream group 8 to be spatially multiplexed. For example, the antenna selection unit 33 adds the selected stream 7-m to the spatially multiplexed stream group 8 (step S208).
- the antenna selection unit 33 excludes the stream 7-m added to the stream group 8 to be spatially multiplexed from the candidates for the stream 7 to be spatially multiplexed. For example, the antenna selection unit 33 excludes the stream 7-m added to the spatially multiplexed stream group 8 from the candidates for the spatially multiplexed stream 7 (step S209).
- the antenna selection unit 33 determines whether or not the number of streams 7 added to the spatially multiplexed stream group 8 is less than the maximum number of layers of multi-user MIMO (eg, 8). That is, the antenna selection unit 33 determines whether or not it is possible to further add the stream 7 to the spatially multiplexed stream group 8 (step S210).
- the antenna selection unit 33 When it is determined that the number of streams 7 added to the spatially multiplexed stream group 8 is equal to the maximum number of layers of multi-user MIMO (step S210: YES), the antenna selection unit 33 performs spatial multiplexing. Determine whether there are any remaining candidates for stream 7. That is, the antenna selection unit 33 determines whether or not the number of candidates for the stream 7 to be spatially multiplexed is 0 (step S211).
- step S210 When it is determined that the number of streams 7 added to the spatially multiplexed stream group 8 is less than the maximum value of the number of layers of multi-user MIMO (step S210: NO), the antenna selection unit 33 terminates the process. .
- step S211: YES When it is determined that there remains a candidate for spatially multiplexed stream 7 (step S211: YES), the antenna selection unit 33 returns the process to step S205. If it is determined that there are no remaining candidates for spatially multiplexed stream 7 (step S211: NO), antenna selection section 33 terminates the process.
- step S206 When it is determined in step S206 that the antenna 4-m associated with the selected stream 7-m has already been selected (step S206: YES), the antenna selection unit 33 selects the selected stream 7-m. m is excluded from candidates for stream 7 to be spatially multiplexed (step S212). Moreover, the antenna selection part 33 returns a process to step S205.
- the terminal selection unit 30 selects one or more user terminals 5 .
- the prediction unit 31 derives a prediction value of the amount of interference between streams transmitted from the plurality of antennas 4 for one or more selected user terminals 5 .
- the collection unit 32 collects the received power values of the beams 6 of the streams 7 included in the stream group 8 from one or more selected user terminals 5 when the predicted value of the interference amount of the stream group is less than the threshold.
- the antenna selection unit 33 selects a plurality of streams 7 in descending order of beam reception power values of the streams.
- the antenna selection unit 33 selects multiple antennas 4 associated with the multiple selected streams 7 .
- the communication unit 34 transmits the selected streams 7 by beamforming using the selected antennas 4 .
- the radio communication system can improve communication capacity while suppressing an increase in processing load without collecting channel estimation values between each antenna and each user terminal.
- the received power value is a simpler index than the channel estimation value (an index that does not require a high processing load).
- FIG. 5 is a flow chart showing an operation example of the wireless communication system 1 in the modified example of the embodiment. Step S201 shown in FIG. 5 is similar to step S201 shown in FIG.
- the prediction unit 31 derives a prediction value of the interference amount of the stream group transmitted from the multiple antennas 4 for one or more selected user terminals 5 .
- the collection unit 32 determines whether or not the predicted value of the interference amount of the stream group is less than a predetermined threshold (step S202b). When it is determined that the predicted value of the interference amount of the stream group is less than the predetermined threshold (step S202b: YES), the collection unit 32 advances the process to step S203.
- the antenna selection unit 33 selects the allocation method that takes into consideration the interference amount between the streams, and uses the first implementation method. Assignment (allocation) of streams to the user terminals 5 is performed by a predetermined method different from the assignment method shown in the form. That is, the antenna selection unit 33 allocates the spatially multiplexed stream group 8 to the plurality of antennas 4 based on a predetermined condition so that the amount of interference between the streams is reduced (step S213). The antenna selection unit 33 terminates the processing.
- the predetermined condition may be any condition as long as the amount of interference between streams is reduced.
- the antenna selection unit 33 selects the spatial Multiplexed stream groups 8 are assigned to multiple antennas 4 . This makes it possible to improve the communication capacity while suppressing an increase in the processing load.
- FIG. 6 is a diagram illustrating a hardware configuration example of a wireless communication device according to the embodiment.
- a processor 100 such as a CPU (Central Processing Unit) is a storage device having a non-volatile recording medium (non-temporary recording medium) for some or all of the functional units of the base station 3 (wireless communication device). It is implemented as software by executing a program stored in 102 and memory 101 . The program may be recorded on a computer-readable recording medium.
- Computer-readable recording media include portable media such as flexible discs, magneto-optical discs, ROM (Read Only Memory), CD-ROM (Compact Disc Read Only Memory), and storage such as hard disks built into computer systems. It is a non-temporary recording medium such as a device.
- Some or all of the functional units of the wireless communication system 1 may use, for example, LSI (Large Scale Integrated circuit), ASIC (Application Specific Integrated Circuit), PLD (Programmable Logic Device), or FPGA (Field Programmable Gate Array). may be implemented using hardware including electronic circuits or circuitry.
- LSI Large Scale Integrated circuit
- ASIC Application Specific Integrated Circuit
- PLD Programmable Logic Device
- FPGA Field Programmable Gate Array
- the present invention is applicable to distributed antenna systems performing single-user MIMO (SU-MIMO) and multi-user MIMO (MU-MIMO).
- SU-MIMO single-user MIMO
- MU-MIMO multi-user MIMO
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Abstract
Description
(概要)
実施形態の無線通信システムは、分散配置された全てのアンテナのうちの少なくとも一部のアンテナを用いてストリーム(データ系列)を無線通信するシステム(分散アンテナシステム)である。無線通信システムでは、アンテナごとに1本のストリームが、そのアンテナごとに1本のビームを用いて、ユーザ端末に送信される。したがって、複数のストリーム(ストリーム群)がユーザ端末に割り当てられた場合には、そのユーザ端末に向けて、割り当てられた複数のストリーム(ビーム)が複数のアンテナから送信される。
図1は、無線通信システム1の構成例を示す図である。無線通信システム1は、分散配置された全てのアンテナのうちの少なくとも一部のアンテナを用いてストリームを無線通信するシステム(分散アンテナシステム)である。無線通信システム1は、上位装置2と、基地局3と、複数のアンテナ4と、1以上のユーザ端末5とを備える。
基地局3は、端末選択部30と、予測部31と、収集部32と、アンテナ選択部33と、通信部34(送信部、受信部)とを備える。
図2は、空間多重されるストリーム群8へのストリーム7の追加例(ユーザ端末へのストリームの割り当て例)を示す図である。図2では、選択されたユーザ端末5は、一例として、ユーザ端末5-1と、ユーザ端末5-2と、ユーザ端末5-3とである。
図3は、無線通信システム1の動作例を示すシーケンス図である。上位装置2は、ユーザ端末5-n(nは1以上の整数)宛てのストリームの識別子を、ストリームの割り当て要求として基地局3に送信する(ステップS101)。基地局3は、ストリームの識別子に基づいて、ストリームが割り当てられる1以上のユーザ端末5-nを選択する(ステップS102)。基地局3は、選択された1以上のユーザ端末5-nについて、ストリーム同士の干渉量の予測値を導出する(ステップS103)。
図5は、実施形態の変形例における、無線通信システム1の動作例を示すフローチャートである。図5に示されたステップS201は、図4に示されたステップS201と同様である。
図6は、実施形態における、無線通信装置のハードウェア構成例を示す図である。基地局3(無線通信装置)の各機能部のうちの一部又は全部は、CPU(Central Processing Unit)等のプロセッサ100が、不揮発性の記録媒体(非一時的な記録媒体)を有する記憶装置102とメモリ101とに記憶されたプログラムを実行することにより、ソフトウェアとして実現される。プログラムは、コンピュータ読み取り可能な記録媒体に記録されてもよい。コンピュータ読み取り可能な記録媒体とは、例えばフレキシブルディスク、光磁気ディスク、ROM(Read Only Memory)、CD-ROM(Compact Disc Read Only Memory)等の可搬媒体、コンピュータシステムに内蔵されるハードディスク等の記憶装置などの非一時的な記録媒体である。
Claims (8)
- 1以上のユーザ端末を選択する端末選択部と、
選択された前記1以上のユーザ端末について、複数のアンテナから送信されるストリーム群の干渉量の予測値を導出する予測部と、
前記干渉量の予測値が閾値未満である場合、前記ストリーム群に含まれるストリームのビームの受信電力値を、選択された前記1以上のユーザ端末から収集する収集部と、
前記受信電力値が大きい順に複数の前記ストリームを選択し、選択された複数の前記ストリームに対応付けられた複数の前記アンテナを選択するアンテナ選択部と、
選択された複数の前記ストリームを、選択された複数の前記アンテナを用いてビームフォーミングによって送信する送信部と
を備える無線通信装置。 - 前記予測部は、複数の前記アンテナと送信される複数の前記ストリームとの組み合わせに基づいて、前記ストリーム同士の干渉量の予測値を導出する、請求項1に記載の無線通信装置。
- 前記予測部は、複数の前記アンテナの位置関係と前記アンテナごとのアンテナ素子の個数に応じたビーム幅とに基づいて、前記ストリーム同士の干渉量の予測値を導出する、請求項1に記載の無線通信装置。
- 前記端末選択部は、ランク指標と所定のスケジューリング処理とに基づいて、前記1以上のユーザ端末を選択する、請求項1から請求項3のいずれか一項に記載の無線通信装置。
- 前記端末選択部は、比例公平性と所定のスケジューリング処理とに基づいて、前記1以上のユーザ端末を選択する、請求項1から請求項3のいずれか一項に記載の無線通信装置。
- 前記端末選択部は、前記アンテナから送信された前記ストリームの受信電力が高いユーザ端末から順に、前記1以上のユーザ端末を選択する、請求項1から請求項3のいずれか一項に記載の無線通信装置。
- 前記端末選択部は、前記アンテナから送信された前記ストリームのビームの受信電力値が類似する前記1以上のユーザ端末を選択する、請求項1から請求項3のいずれか一項に記載の無線通信装置。
- 無線通信装置が実行する無線通信方法であって、
1以上のユーザ端末を選択する端末選択ステップと、
選択された前記1以上のユーザ端末について、複数のアンテナから送信されるストリーム群の干渉量の予測値を導出する予測ステップと、
前記干渉量の予測値が閾値未満である場合、前記ストリーム群に含まれるストリームのビームの受信電力値を、選択された前記1以上のユーザ端末から収集する収集ステップと、
前記受信電力値が大きい順に複数の前記ストリームを選択し、選択された複数の前記ストリームに対応付けられた複数の前記アンテナを選択するアンテナ選択ステップと、
選択された複数の前記ストリームを、選択された複数の前記アンテナを用いてビームフォーミングによって送信する送信ステップと
を含む無線通信方法。
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