WO2013157046A1 - Station sans fil et système de communication sans fil - Google Patents

Station sans fil et système de communication sans fil Download PDF

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Publication number
WO2013157046A1
WO2013157046A1 PCT/JP2012/002744 JP2012002744W WO2013157046A1 WO 2013157046 A1 WO2013157046 A1 WO 2013157046A1 JP 2012002744 W JP2012002744 W JP 2012002744W WO 2013157046 A1 WO2013157046 A1 WO 2013157046A1
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Prior art keywords
radio
transmission
wireless
information
base station
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PCT/JP2012/002744
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English (en)
Japanese (ja)
Inventor
義博 河▲崎▼
好明 太田
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富士通株式会社
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Priority to PCT/JP2012/002744 priority Critical patent/WO2013157046A1/fr
Publication of WO2013157046A1 publication Critical patent/WO2013157046A1/fr

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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W28/00—Network traffic management; Network resource management
    • H04W28/02—Traffic management, e.g. flow control or congestion control

Definitions

  • the technology disclosed in one aspect of the embodiments of the present invention relates to a radio station and a radio communication system.
  • wireless terminals called smartphones have become widespread, and smartphone users are increasing.
  • the number of wireless terminals that the wireless base station should accommodate in the wireless cell is steadily increasing.
  • a wireless terminal such as a smartphone is more dependent on the user's position and behavior than the wireless terminal mainly for voice communication, and real-time performance is strongly required for information collection. Has characteristics.
  • a wireless terminal called a smartphone is in a semi-connected state with respect to a wireless base station so that necessary information can be acquired in real time when necessary.
  • the power consumption of the wireless terminal increases.
  • 3GPP Third Generation Partnership Project
  • IEEE 802.16 As means for realizing a semi-connected state to a base station with low power consumption, it is known to apply an intermittent data reception operation to a wireless terminal.
  • communication of wireless data performed by a wireless terminal such as a smartphone with a wireless base station is more likely to be intermittent as compared to communication performed by a wireless terminal mainly using voice communication.
  • Patent Document 1 an example using an intermittent reception method in communication in a transmission diversity method with a plurality of base stations is described in Patent Document 1 below.
  • the radio base station transmits an evaluation report on downlink radio characteristics and a downlink transmission from each radio terminal present in the radio cell.
  • a feedback signal including feedback information such as transmission parameters (for example, modulation scheme / coding rate, spatial code matrix) applied to the data signal to be received is received. Therefore, it is necessary for the radio base station to periodically assign radio resources in the uplink (uplink communication from the radio terminal to the radio base station) to the radio terminal in advance.
  • a radio terminal periodically evaluates radio characteristics of a downlink (downlink communication from a radio base station to a radio terminal). Then, based on the radio resource allocated to the uplink, a feedback signal including information of the evaluation report is transmitted to the base station.
  • the wireless terminal periodically calculates a desired value of transmission parameters (for example, modulation scheme / coding rate, spatial code matrix) applied to downlink data transmission, and based on allocated radio resources, A feedback signal including information on the desired value of the calculated transmission parameter (for example, CQI (Channel Quality Indicator), PMI (Precoding Matrix Indicator)) is transmitted to the radio base station.
  • a desired value of transmission parameters for example, modulation scheme / coding rate, spatial code matrix
  • the number of radio terminals that can be accommodated in the radio cell by the radio base station is assigned to the total amount of uplink radio resources allocated to receive the above-described feedback signal and to one radio terminal.
  • the amount of uplink radio resources there is an upper limit determined by the amount of uplink radio resources, increasing the total amount of radio resources for transmitting the above feedback signal itself sacrifices radio resources allocated to receive data from the radio terminal. Therefore, there is a problem that it is not preferable.
  • a wireless terminal that can be accommodated in a wireless cell by a wireless base station without increasing the total amount of wireless resources for transmitting the feedback signal described above.
  • the purpose is to increase the number.
  • a wireless communication system includes a plurality of second wireless stations that receive data from the first wireless station according to a plurality of transmission schemes having different amounts of feedback information for transmission from the first wireless station.
  • the first wireless station sets a communication frame for transmitting data to the second wireless station from a plurality of communication frames in a first cycle, and the second wireless station
  • Each of the radio stations determines the degree of congestion of the plurality of second radio stations in the first radio station according to the length of the first cycle.
  • FIG. 7 is a diagram for explaining an intermittent transmission operation mode executed in a radio base station 102.
  • 5 is a flowchart for explaining a communication control method in wireless communication system 100. It is a functional block diagram which shows the structure of the wireless base station 102 which concerns on 1st Example. 5 is a flowchart (No. 1) for describing a communication control method in the radio base station 102; 4 is a flowchart (part 2) for explaining a communication control method in the radio base station 102; It is a functional block diagram which shows the structure of the radio
  • FIG. 6 is a flowchart (part 1) for explaining a communication control method in the wireless terminal 104; 6 is a flowchart (part 2) for describing a communication control method in the wireless terminal 104; FIG. 2 is a hardware configuration diagram illustrating an example of configurations of a radio base station 102 and a radio terminal 104.
  • LTE will be described as an example of a communication method, but the communication method to which the present invention is applied is not limited to LTE.
  • the present invention can be applied to other communication schemes, and can be applied to, for example, LTE-Advanced.
  • FIG. 1 is a schematic diagram illustrating a configuration of a wireless communication system according to the first embodiment.
  • the radio communication system 100 is a system in which data communication based on LTE is performed.
  • the radio base station 102 transmits / receives a control signal for establishing a radio link to / from each radio terminal 104, thereby forming a link with each radio terminal 104, and each radio terminal using the formed link.
  • 104 performs data communication.
  • FIG. 1 only two wireless terminals 104-1 and 2 are shown, but the present invention is not limited to this, and there are three or more wireless terminals 104 for one wireless relay station 102. Also good.
  • radio communication system including a radio base station and a radio terminal
  • both of the radio base station and the radio terminal are only examples of radio stations constituting the radio communication system. There is nothing.
  • the radio base station 102 has at least two continuous transmission operation modes and intermittent transmission operation modes as operation modes for transmitting data to the radio terminal 104.
  • the radio base station 102 performs a continuous transmission operation mode and an intermittent transmission operation mode for each radio terminal 104 according to the number of radio terminals 104 present in the radio cell 106 and the state of the data transmission amount to each radio terminal. Apply one of the following:
  • the radio base station 102 transmits data to the radio terminal 104 according to the applied operation mode.
  • the wireless base station 102 applies the intermittent transmission operation mode to the wireless terminals 104.
  • the radio base station 102 may apply the intermittent transmission operation mode to all the radio terminals 104 included in the radio cell 106, but selectively to some of the radio terminals 104. It is preferable to apply the intermittent transmission operation mode.
  • the radio base station 102 selectively applies the intermittent transmission operation mode to the radio terminal 104 whose data transmission pattern is bursty.
  • the radio base station 102 selectively applies the intermittent transmission operation mode, for example, to the radio terminal 104 with a small amount of data traffic.
  • the radio base station 102 applies the continuous transmission operation mode to the radio terminal 104 that does not apply the intermittent transmission operation mode. Details of the intermittent transmission operation mode and the continuous transmission operation mode will be described later.
  • each of the wireless base station 102 and each wireless terminal 104 has a plurality of transmission / reception antennas.
  • the radio base station 102 performs data communication with each radio terminal 104 using the multi-antenna radio transmission technology.
  • the wireless base station 102 can apply an open-loop transmission method and a closed-loop transmission method.
  • the radio base station 102 selects either an open-loop transmission method or a closed-loop transmission method, and transmits data to each wireless terminal 104 based on the selected transmission method. Send a signal.
  • the transmission method selection operation applied when the radio base station 102 transmits a data signal to the radio terminal 104 will be described later.
  • Open-loop transmission schemes include, for example, an open-loop transmission diversity scheme and an open-loop spatial multiplexing transmission scheme (Open-loop MIMO).
  • Open-loop MIMO open-loop spatial multiplexing transmission scheme
  • the open-loop transmission diversity scheme is a scheme for determining transmission parameters without referring to feedback information included in a feedback signal transmitted from the wireless terminal 104.
  • Open-loop transmission diversity schemes include, for example, space frequency block coding diversity (SFBC (Space-Frequency-Block Code) -diversity), space-time block coding diversity (STBC-(Space-Time Block Code) -diversity), cyclic delay diversity (Cyclic) Delay Diversity), but SFBC diversity is mainly used in LTE.
  • the radio terminal 104 applies the modulation scheme applied to the data signal transmitted to the radio base station 102.
  • the open-loop spatial multiplexing transmission scheme is a transmission scheme using MIMO (Multiple Input Multiple Multiple Output) technology, and is a scheme adopted in LTE.
  • MIMO Multiple Input Multiple Multiple Output
  • LTE Long Term Evolution
  • the radio terminal 104 When the open-loop spatial multiplexing scheme is applied to the data signal to be transmitted from the radio base station 102 to the radio terminal 104, the radio terminal 104 is applied to the data signal that is not transmitted to the radio base station 102.
  • a feedback signal including information on the desired value of the multiplexing number (rank) and the desired value of the modulation scheme / coding rate is transmitted.
  • the wireless terminal 104 independently encodes the desired value of the modulation scheme and coding rate and the desired value of the spatial multiplexing number (rank), or jointly codes the desired values of both. Send as one value.
  • the closed-loop transmission method includes, for example, a closed-loop spatial multiplexing transmission method (Closed-loop MIMO).
  • the closed-loop spatial multiplexing scheme is a transmission scheme using MIMO technology, and is a scheme adopted in LTE.
  • the closed-loop spatial multiplexing scheme refers to feedback information included in a feedback signal transmitted from the wireless terminal 104 when the wireless base station 102 performs a spatial multiplexing process on a data signal to be transmitted to the wireless terminal 104. In this way, a transmission parameter such as a spatial code is determined.
  • the wireless terminal 104 applies a modulation method or data applied to the data signal transmitted to the wireless base station 102.
  • a feedback signal including information on the desired value of the coding rate, the desired value of the spatial multiplexing number (rank), and the desired value of the spatial code matrix is transmitted.
  • the radio terminal 104 independently sets the desired value of the spatial multiplexing number (rank), the desired value of the modulation scheme / coding rate, and the desired value of the spatial code matrix, or jointly codes each desired value. (Joint coding) and transmit as one value.
  • FIG. 2 is a diagram for explaining the intermittent transmission operation mode executed in the radio base station 102, and is a diagram for explaining the arrangement of On-duration subframes in the downlink radio section.
  • data transmission from the radio base station 102 to each radio terminal 104 is performed in units of radio subframes in a radio section constituted by a plurality of radio subframes.
  • One radio subframe has a physical layer downlink control signal (PDCCH (Physical Downlink Control Channel)) corresponding to a data signal (PDSCH (Physical Downlink Shared Channel)) transmitted in the radio subframe at the head thereof.
  • PDCCH Physical Downlink Control Channel
  • PDSCH Physical Downlink Shared Channel
  • the physical layer downlink control signal and the data signal may be referred to as PDCCH and PDSCH, which are terms in 3GPP LTE, respectively.
  • the PDCCH includes information indicating a frequency band / frequency position in a corresponding PDSCH radio subframe, information indicating a modulation scheme / coding rate applied to the PDSCH, and HARQ (for controlling retransmission operation of the PDSCH).
  • Hybrid Automatic repeat request for controlling retransmission operation of the PDSCH.
  • data transmission from the radio base station 102 to the plurality of radio terminals 104 is performed using one radio subframe. Therefore, a plurality of PDCCHs corresponding to a plurality of wireless terminals 104 that are data transmission targets are included in the head part of the wireless subframe.
  • the wireless base station 102 selects a part of the wireless sub-stations having a certain generation period from a plurality of wireless sub-claims included in the downlink wireless section. Specify the frame as an On-duration subframe.
  • the On-duration subframe is a radio subframe used for data transmission when there is a PDSCH to be transmitted to the radio terminal 104.
  • the generation period of the On-duration subframe may be a predetermined value, or the number of the wireless terminals 104 to which the intermittent transmission operation mode is applied or the wireless terminals 104 to which the intermittent transmission operation mode is applied It may be determined adaptively based on the amount of data traffic.
  • the radio base station 102 transmits to the radio terminal 104 an intermittent transmission operation mode control signal including information indicating that the intermittent transmission operation mode is applied and information on the generation period of the On-duration subframe.
  • the wireless base station 102 When the intermittent transmission operation mode is applied to the wireless terminal 104 to be transmitted, the wireless base station 102 selectively transmits the PDSCH in an On-duration subframe having a certain generation period from among a plurality of wireless subclaims. In other radio subframes, PDSCH is not transmitted.
  • the wireless terminal 104 receives the above intermittent transmission operation mode control signal from the wireless base station 102. Based on the received intermittent transmission operation mode control signal, the wireless terminal 104 identifies an On-duration subframe having a certain generation period from among a plurality of wireless subclaims. In the identified On-duration subframe, the wireless terminal 104 performs a detection process to determine whether PDCCH is transmitted to the own terminal, and decodes the PDCCH when the PDCCH for the own terminal is detected. Then, the wireless terminal 104 acquires PDSCH information for the terminal transmitted in the On-duration subframe, and performs PDSCH demodulation / decoding processing for the terminal based on the acquired information. The radio terminal 104 does not perform the PDCCH detection process and PDSCH reception operation in radio subframes other than the On-duration subframe.
  • the radio base station 102 transmits the PDSCH in the On-duration subframe to the transmission target radio terminal 104, an open-loop transmission scheme and a closed-loop transmission are performed according to the generation period of the On-duration subframe.
  • the transmission method applied to data transmission is switched between methods.
  • the open loop transmission scheme is, for example, an open loop transmission diversity scheme or an open loop spatial multiplexing transmission scheme.
  • the closed loop transmission scheme is, for example, a closed loop spatial multiplexing transmission scheme.
  • the radio base station 102 When the generation period of the On-duration subframe is longer than a certain threshold, the radio base station 102 applies only the open-loop transmission scheme, regardless of the downlink radio characteristics with the radio terminal 104 to be transmitted. The PDSCH is transmitted to the wireless terminal 104 using only the open loop transmission method. On the other hand, when the generation period of the On-duration subframe is shorter than a certain threshold, the radio base station 102 applies both the open-loop transmission method and the closed-loop transmission method, and The PDSCH is transmitted to the radio terminal 104 using either an open-loop transmission scheme or a closed-loop transmission scheme according to the downlink radio characteristics.
  • the radio base station 102 notifies the transmission target radio terminal 104 of threshold information related to the generation period of the On-duration subframe by the intermittent transmission operation mode control signal described above.
  • the threshold for the generation period of the On-duration subframe may be a predetermined value, or the number of wireless terminals 104 to which the intermittent transmission operation mode is applied, the number of reception antennas of the wireless terminal 104, the wireless base station It may be determined periodically and adaptively based on the load state of 102, and periodically notified to the wireless terminal 104.
  • the wireless terminal 104 receives the above intermittent transmission operation mode control signal from the wireless base station 102.
  • the wireless terminal 104 acquires information such as the generation period of the On-duration subframe and the threshold value of the generation period from the received intermittent transmission operation mode control signal.
  • the wireless terminal 104 recognizes that only the open-loop transmission scheme is applied to data reception from the wireless base station 102 when the generation cycle of the acquired On-duration subframe is longer than the acquired threshold,
  • the PDSCH is received from the radio base station 102 using only the open loop transmission method. That is, the wireless terminal 104 performs blind detection only on the PDCCH corresponding to the open-loop transmission scheme in the On-duration subframe, and receives the PDSCH based on the detected PDCCH.
  • the wireless terminal 104 has both an open-loop transmission method and a closed-loop transmission method for data reception from the wireless base station 102. Recognizing the application, the data signal is received from the radio base station 102 using both the open-loop transmission scheme and the closed-loop transmission scheme. That is, in the On-duration subframe, the wireless terminal 104 performs blind detection on two types of PDCCHs, a PDCCH corresponding to the open-loop transmission scheme and a PDCCH corresponding to the closed-loop transmission scheme, and detects the detected PDCCH.
  • the wireless terminal 104 receives a data signal according to the transmission method obtained by the determination.
  • DCI Downlink Control Information
  • FIG. 3 is a flowchart for explaining a communication control method in radio communication system 100.
  • an example using an open-loop transmission diversity scheme is shown as an open-loop transmission scheme, but an open-loop spatial multiplexing transmission scheme can be used instead. is there.
  • the radio base station 102 performs data communication in the continuous transmission operation mode with the radio terminal 104 to be transmitted.
  • the radio base station 102 applies both the open-loop transmission diversity scheme and the closed-loop spatial multiplexing transmission scheme to the data signal transmitted to the radio terminal 104.
  • the radio base station 102 determines whether or not to switch the PDSCH transmission mode to the transmission target radio terminal 104 from the continuous transmission operation mode to the intermittent transmission operation mode.
  • the radio base station 102 determines whether to switch the PDSCH transmission mode from the continuous transmission operation mode to the intermittent transmission operation mode according to the number of radio terminals 104 present in the radio cell 106. For example, when the number of radio terminals 104 is greater than a predetermined value, the radio base station 102 switches the PDSCH transmission mode for the radio terminals 104 from the continuous transmission operation mode to the intermittent transmission operation mode. If the intermittent transmission operation mode is applied, the process proceeds to step S306. If the intermittent transmission operation mode is not applied, the process proceeds to step S308.
  • the radio base station 102 transmits an intermittent transmission operation mode control signal including intermittent transmission operation mode control information (intermittent transmission operation mode control information) to the wireless terminal 104 to be transmitted.
  • the intermittent transmission operation mode control information includes information indicating that the intermittent transmission operation mode is applied, information on an occurrence period of an On-duration subframe in which a data signal is transmitted in the intermittent transmission operation mode, and an On-duration subframe. Information on the threshold related to the occurrence period.
  • the radio base station 102 designates predetermined values as the generation period of the On-duration subframe and the threshold value related to the generation period.
  • step S308 the radio base station 102 continues data communication in the continuous transmission operation mode with the radio terminal 104 to be transmitted.
  • step S310 the radio base station 102 determines whether or not the generation period of the On-duration subframe specified in step S306 is longer than the specified threshold. Similarly, the wireless terminal 104 determines whether the generation cycle of the designated On-duration subframe is longer than the designated threshold value. If the generation period of the On-duration subframe is longer than the threshold, the process proceeds to step S312. If the generation period of the On-duration subframe is equal to or less than the threshold, the process proceeds to step S316.
  • step S312 the wireless terminal 104 that is the transmission target determines that the generation period of the designated On-duration subframe is longer than the designated threshold, so that the wireless base station 102 covers the wireless cell 106. It is determined that the number of existing wireless terminals 104 exceeds a certain allowable value, and the degree of congestion of the wireless terminals 104 in the wireless cell 106 exceeds a certain allowable level. Then, the wireless terminal 104 recognizes that the open loop transmission diversity scheme is applied to the data signal transmitted from the wireless base station 102.
  • the transmission target wireless terminal 104 transmits, to the wireless base station 102, a feedback signal including information on a desired value of the modulation scheme / coding rate applied to the transmitted PDSCH.
  • the communication control unit 402 does not transmit information on the spatial multiplexing number (rank) and the desired value of the spatial code matrix as a feedback signal.
  • the radio base station 102 can reduce the allocation of radio resources in the uplink for transmission of feedback signals compared to the case where the closed-loop spatial multiplexing transmission method in step S316 described later is applied. it can.
  • the radio base station 102 receives the feedback signal from the radio terminal 104, and based on the received feedback signal, the modulation scheme / coding rate desired by the radio terminal 104 to be transmitted for the transmitted PDSCH Get the value of.
  • the information amount of the feedback signal transmitted from the wireless terminal 104 to the wireless base station 102 is 10 bits per subband, and the information amount of the desired value of the modulation scheme / coding rate is 4 bits. It is.
  • the subband is a minimum unit when the downlink transmission band is divided into a plurality of equal width regions, and the radio terminal 104 measures and evaluates the downlink radio characteristics for each subband.
  • step S314 the radio base station 102 performs encoding / modulation processing based on the desired value of the modulation scheme / coding rate acquired in step S312, thereby transmitting a data signal ( PDSCH) is generated.
  • the radio base station 102 transmits the generated data signal (PDSCH) to the radio terminal 104 to be transmitted by an open loop transmission diversity method.
  • the radio base station 102 employs, for example, SFBC diversity as an open-loop transmission diversity scheme.
  • the radio base station 102 determines the transmission parameters of the open loop transmission diversity scheme without referring to the feedback information included in the feedback signal transmitted from the radio terminal 104.
  • the wireless terminal 104 to be transmitted receives the PDSCH transmitted from the wireless base station 102. At this time, the wireless terminal 104 selectively receives the PDCCH corresponding to the open-loop transmission diversity scheme by blind detection prior to receiving the PDSCH, but does not receive the PDCCH corresponding to the closed-loop spatial multiplexing transmission scheme. The wireless terminal 104 acquires data by performing demodulation / decoding processing on the received data signal.
  • Steps S312 and S314 correspond to the second transmission mode of processing in the radio base station 102 and correspond to the second reception mode of processing in the radio terminal 104.
  • step S316 the wireless terminal 104 that is the transmission target determines that the generation period of the specified On-duration subframe is equal to or less than the specified threshold, whereby the wireless cell 106 covered by the wireless base station 102 is obtained. It is determined that the number of wireless terminals 104 existing in the wireless cell 104 is within a certain allowable value, and the degree of congestion of the wireless terminals 104 in the wireless cell 106 is below a certain allowable level. Then, the wireless terminal 104 recognizes that both the open-loop transmission diversity scheme and the closed-loop spatial multiplexing transmission scheme are applied to the data signal transmitted from the wireless base station 102.
  • the radio terminal 104 to be transmitted to the radio base station 102 applies a desired value of the modulation scheme and coding rate, a desired value of the spatial multiplexing number (rank) applied to the data signal to be transmitted, and A feedback signal including information on a desired value of the spatial code matrix is transmitted.
  • the radio base station 102 receives the feedback signal from the radio terminal 104, and based on the received feedback signal, the modulation scheme / coding desired by the radio terminal 104 to be transmitted for the data signal to be transmitted A rate value, a spatial multiplexing number value, and a spatial code matrix value are acquired.
  • the information amount of the feedback signal transmitted from the wireless terminal 104 to the wireless base station 102 is 10 bits per subband.
  • the information amount of the desired value of the modulation scheme and coding rate is 4 bits
  • the information amount of the desired value of the spatial multiplexing number is 2 bits
  • the information amount of the spatial code matrix is 4 bits.
  • the radio base station 102 performs a coding / modulation process based on the desired value of the modulation scheme / coding rate acquired in step S316, thereby transmitting a data signal to be transmitted to the wireless terminal 104.
  • the radio base station 102 transmits the generated data signal to the radio terminal 104 that is a transmission target by using either the open-loop transmission diversity scheme or the closed-loop spatial multiplexing transmission scheme.
  • the radio base station 102 transmits a transmission parameter such as a spatial code in the open-loop spatial multiplexing transmission scheme such as a spatial multiplexing number (rank) and a spatial code matrix included in the feedback signal transmitted from the radio terminal 104. Determine by referring to the feedback information.
  • the radio base station 102 transmits information on an evaluation report of downlink radio characteristics transmitted from the radio terminal 104 to be transmitted, which of the open loop transmission diversity scheme and the closed loop spatial multiplexing transmission scheme is adopted. Determine based on. For example, the radio base station 102 adopts an open-loop transmission diversity scheme when the fluctuation of downlink radio characteristics is large based on the information of the evaluation report, and when the fluctuation is small, closed-loop spatial multiplexing transmission Adopt the method.
  • the wireless terminal 104 to be transmitted receives the data signal transmitted from the wireless base station 102.
  • the wireless terminal 104 acquires data by performing demodulation / decoding processing on the received data signal.
  • Steps S316 and S318 correspond to the first transmission mode of processing in the radio base station 102 and correspond to the first reception mode of processing in the radio terminal 104.
  • step S320 after transmitting the data signal to the wireless terminal 104 in step S314 or S318, the wireless base station 102 determines whether or not it is necessary to update the intermittent transmission operation mode control information for the wireless terminal 104 to be transmitted. judge. When it is necessary to update the intermittent transmission operation mode control information, the radio base station 102 generates an intermittent transmission operation mode control signal including the updated intermittent transmission operation mode control information, and the generated intermittent transmission operation mode control signal Is transmitted to the wireless terminal 104 to be transmitted.
  • the transmission target wireless terminal 104 receives an intermittent transmission operation mode control signal including the updated intermittent transmission operation mode control information from the wireless base station 102.
  • step S322 If the updated intermittent transmission operation mode control signal is not transmitted, the process returns to step S310.
  • the radio base station 102 determines whether or not to maintain the intermittent transmission operation mode as the transmission mode of the PDSCH to the radio terminal 104 to be transmitted.
  • the radio base station 102 does not maintain the intermittent transmission operation mode as the operation mode, that is, when it is determined to switch the operation mode from the intermittent transmission operation mode to the continuous transmission operation mode, the radio base station 102 indicates that the intermittent transmission operation mode is canceled.
  • An intermittent transmission operation mode control signal including information is generated. For example, when the number of the wireless terminals 104 becomes smaller than a predetermined value, the wireless base station 102 determines to cancel the intermittent transmission operation mode.
  • the radio base station 102 determines whether or not to change the generation period of the On-duration subframe.
  • the radio base station 102 decides to change the generation period of the On-duration subframe, the radio base station 102 generates an update value of the generation period of the On-duration subframe, and intermittent transmission operation including information of the generated update value A mode control signal is generated.
  • the radio base station 102 for example, based on the number of radio terminals 104 to which the intermittent transmission operation mode is applied, the amount of data traffic to the radio terminals 104 to which the intermittent transmission operation mode is applied, and the like,
  • the generation period is determined adaptively. For example, when the number of wireless terminals 104 to which the intermittent transmission operation mode is applied increases, the wireless base station 102 lengthens the generation period of the On-duration subframe corresponding to each wireless terminal 104. For example, when the amount of data traffic for the wireless terminal 104 to which the intermittent transmission operation mode is applied decreases, the wireless base station 102 lengthens the generation period of the On-duration subframe corresponding to each wireless terminal 104.
  • the radio base station 102 determines whether or not to change the threshold related to the generation period of the On-duration subframe.
  • the radio base station 102 decides to change the threshold value related to the generation period of the On-duration subframe, the radio base station 102 generates information on the update value of the threshold value related to the generation period of the On-duration subframe, and the generated update value Including intermittent transmission operation mode control signal is generated.
  • the radio base station 102 adaptively determines a threshold related to the generation period of the On-duration subframe based on the number of radio terminals 104 to which the intermittent transmission operation mode is applied. For example, when the number of wireless terminals 104 to which the intermittent transmission operation mode is applied increases, the wireless base station 102 decreases the threshold regarding the generation period of the On-duration subframe corresponding to each wireless terminal 104.
  • step S322 the radio base station 102 cancels the intermittent transmission operation mode as the transmission mode of the PDSCH to the transmission target wireless terminal 104 based on the intermittent transmission operation mode control signal updated in step S320. Whether to switch to the continuous transmission operation mode is determined.
  • the wireless base station 102 in the transmission mode cancels the intermittent transmission operation mode as the operation mode in the wireless base station 102 and switches to the continuous transmission operation mode. It is determined whether or not it has been. If the intermittent transmission operation mode is cancelled, the process proceeds to step S324. If the intermittent transmission operation mode is not cancelled, the process returns to step S310.
  • step S324 the radio base station 102 shifts to the continuous transmission operation mode with respect to the PDSCH transmission mode, and performs data communication in the continuous transmission operation mode with the radio terminal 104 to be transmitted.
  • step S310 When the intermittent transmission operation mode is not canceled in step S322 and the process returns to step S310, the update value of the generation period of the On-duration subframe generated in step S320 and the generation period are related. Based on the updated value of the threshold value, the processes after step S310 are executed again.
  • the intermittent transmission operation mode is applied to the data signal transmitted to the wireless terminal 104, and the open-loop transmission method (open-loop transmission diversity method) is applied.
  • the wireless terminal 104 transmits the desired value of the modulation scheme and coding rate as feedback information to the wireless base station 102, and does not transmit the desired value of the spatial multiplexing number and the spatial code matrix.
  • the information amount of the feedback signal can be reduced to about half compared to the case where a closed-loop transmission scheme (closed-loop spatial multiplexing transmission scheme) is applied.
  • the radio base station 102 can suppress the amount of radio resources in the uplink allocated to the radio terminal 104 for transmitting a feedback signal to about half.
  • the radio base station 102 can accommodate the radio signal without increasing the total amount of radio resources for transmitting a feedback signal.
  • the number of wireless terminals 104 can be increased.
  • the wireless terminal 104 applies an open-loop transmission method from the wireless base station 102 when an open-loop transmission method (open-loop transmission diversity method) is applied.
  • the data signal transmitted by is received. Therefore, the wireless terminal 104 only needs to detect the PDCCH corresponding to the open-loop transmission scheme when receiving the data signal, and the PDCCH corresponding to the closed-loop transmission scheme (closed-loop spatial multiplexing transmission scheme). Therefore, the number of processes in receiving a data signal can be reduced, and power consumption in receiving a data signal can be reduced.
  • FIG. 4 is a functional block diagram illustrating the configuration of the radio base station 102 according to the first embodiment.
  • a portion indicated by a thick solid line indicates that a plurality of pieces of information including data and various types of control information are transmitted.
  • the radio base station 102 includes a communication control unit 402, encoding processing units 404-1 to 406-1, multiplexing units 406-1 and 2, a time multiplexing unit 408, a modulation processing unit 410, and an RF transmission / reception unit. 412, an antenna unit 414, and a demodulation / decoding processing unit 416.
  • the RF transceiver unit 412 receives a data signal and a feedback signal from each wireless terminal 104 via the antenna unit 414 including a plurality of antennas.
  • the RF transmission / reception unit 412 outputs the received data signal and feedback signal to the demodulation / decoding processing unit 416.
  • the feedback signal includes feedback information including information on the desired value of the modulation scheme and coding rate in wireless terminal 104, the desired value of the spatial multiplexing number (rank), and the desired value of the spatial code matrix.
  • the demodulation / decoding processing unit 416 receives a data signal and a feedback signal from the RF transmission / reception unit 412.
  • the demodulation / decoding processing unit 416 acquires data and feedback information by performing demodulation processing and decoding processing on the received data signal and feedback signal under the control of the communication control unit 402.
  • the demodulation / decoding processing unit 416 outputs the acquired data and feedback information to the communication control unit 402.
  • the communication control unit 402 receives data and feedback information from the demodulation / decoding processing unit 416.
  • the communication control unit 402 executes predetermined processing based on the received data and feedback information to generate data and various control information to be transmitted to each wireless terminal 104, and the generated data and various control information Are output to the encoding processing units 404-1 to 404-1.
  • the control information generated by the communication control unit 402 includes link control information, UL radio resource allocation information, intermittent transmission operation mode control information, common control information, and common control related information. Details of the control information will be described later.
  • the communication control unit 402 is based on control information such as a desired value of the modulation scheme / coding rate, a desired value of the spatial multiplexing number (rank), and a desired value of the spatial code matrix, which are included in the received feedback information.
  • the encoding processing in the encoding processing units 404-1 to 404-1 and the modulation processing in the modulation processing unit 410 are controlled.
  • the encoding processing unit 404-2 receives the common control information from the communication control unit 402.
  • the common control information is control information that is commonly applied to a plurality of radio terminals 105 located in the radio cell 106 covered by the radio base station 102.
  • the encoding processing unit 404-2 generates a common control signal by performing an encoding process on the received common control information under the control of the traffic control unit 402, and the generated common control signal is multiplexed with the multiplexing unit. Output to 406-1.
  • the encoding processing unit 404-1 receives the common control related information from the communication control unit 402.
  • the common control related information is generated along with the common control information, and is control information for complementing the common control information.
  • the encoding processing unit 404-1 generates a common control signal by performing encoding processing on the received common control related information under the control of the traffic control unit 402, and generates the generated common control related signal.
  • the data is output to multiplexing section 406-1.
  • the multiplexing unit 406-1 receives the common control signal and the common control-related signal from the encoding processing units 406-1 and 402-1. Multiplexer 406-1 outputs the received common control signal and common control-related signal to time multiplexer 408, respectively.
  • the signal output from multiplexing section 406-1 corresponds to PDSCH (Common (PDSCH (Physical Downlink Shared Channel)) commonly assigned by a plurality of radio terminals 104 located in radio cell 106 covered by radio base station 102. To do.
  • PDSCH Common (PDSCH (Physical Downlink Shared Channel)
  • the encoding processing unit 404-3 receives the intermittent transmission operation mode control information from the communication control unit 402.
  • the intermittent transmission operation mode control information includes information indicating that the intermittent transmission operation mode is applied, information on the generation period of the On-duration subframe, and threshold values regarding the generation period of the On-duration subframe. Contains information.
  • the encoding processing unit 404-3 generates an intermittent transmission operation mode control signal by performing an encoding process on the received intermittent transmission operation mode control information under the control of the traffic control unit 402.
  • the intermittent transmission operation mode control signal is output to multiplexing section 406-2.
  • the encoding processing unit 404-4 receives UL (Uplink) radio resource allocation information from the communication control unit 402.
  • UL radio resource allocation information is used for radio resources (for signal transmission) in the uplink (uplink communication from the radio terminal to the radio base station) for each radio terminal 104 to transmit the feedback signal to the radio base station 102.
  • This is control information indicating assignment of frequency bands and frequency positions to be assigned.
  • the encoding processing unit 404-4 generates an UL radio resource allocation signal by performing an encoding process on the received UL radio resource allocation information under the control of the traffic control unit 402, and generates the generated UL radio.
  • the resource allocation signal is output to multiplexing section 406-2.
  • the encoding processing unit 404-5 receives data to be transmitted to the wireless terminal 104 from the communication control unit 402.
  • the encoding processing unit 404-5 generates a data signal by performing encoding processing on the received data under the control of the traffic control unit 402, and sends the generated data signal to the multiplexing unit 406-2. Output.
  • the multiplexing unit 406-2 receives intermittent transmission operation mode control signals, UL radio resource allocation signals, and data signals from the encoding processing units 406-3 to 406-3.
  • Multiplexer 406-1 outputs the received intermittent transmission operation mode control signal, UL radio resource allocation signal, and data signal to time multiplexer 408, respectively.
  • a signal output from the multiplexing unit 406-2 is assigned to a PDSCH (Dedicated PDSCH (Physical DownlinkPDShared Channel) individually assigned to each radio terminal 104 located in the radio cell 106 covered by the radio base station 102. Corresponding.
  • PDSCH Dedicated PDSCH (Physical DownlinkPDShared Channel) individually assigned to each radio terminal 104 located in the radio cell 106 covered by the radio base station 102.
  • the encoding processing unit 404-6 receives link control information from the communication control unit 402.
  • the link control information is a control signal accompanying the data output to the encoding processing unit 404-5, information indicating the frequency band / frequency position in the radio subframe of the data, the data It includes information indicating the modulation scheme and coding rate applied to the signal, HARQ (Hybrid automatic repeat request) information for controlling the retransmission operation of the data, and the like.
  • the encoding processing unit 404-6 generates a PDCCH by performing an encoding process on the received link control information under the control of the traffic control unit 402, and transmits the generated PDCCH to the multiplexing unit 406-2.
  • a signal output from the encoding processing unit 404-6 is transmitted to a PDCCH (Physical Downlink Control) Channel)) individually assigned to each radio terminal 104 located in the radio cell 106 covered by the radio base station 102. Corresponding.
  • PDCCH Physical Downlink Control
  • the time multiplexing unit 408 receives the output signal (PDSCH) from the multiplexing units 406-1 and 406-2 and also receives the output signal (PDCCH) from the encoding processing unit 404-6.
  • the time multiplexing unit 408 performs time multiplexing processing on each received output signal and outputs a signal obtained by the time multiplexing processing to the modulation processing unit 410.
  • the time multiplexing unit 408 adjusts the output timing of each received output signal and then outputs the output signal to the modulation processing unit 410.
  • the modulation processing unit 410 receives an output signal from the time multiplexing unit 408.
  • the modulation processing unit 410 performs modulation processing on the received output signal under the control of the communication control unit 402, and outputs a signal obtained by the modulation processing to the RF transmission / reception unit 412.
  • the above-described modulation processing is performed by the communication control unit 402 in various controls such as a desired value of the modulation scheme and coding rate, a desired value of the spatial multiplexing number (rank), and a desired value of the spatial code matrix. Control based on information.
  • the modulation processing unit 410 converts the output signal from the time multiplexing unit 408 into a signal in a format corresponding to either the open-loop transmission method or the closed-loop transmission method by the above-described modulation processing.
  • the open-loop transmission scheme is, for example, an open-loop transmission diversity scheme or an open-loop spatial multiplexing transmission scheme.
  • the closed loop transmission scheme is, for example, a closed loop spatial multiplexing transmission scheme.
  • the RF transmission / reception unit 412 transmits the output signal received from the modulation processing unit 410 to each wireless terminal 104 via the antenna unit 414 including a plurality of antennas.
  • FIGS. 5 and 6 a communication control method performed in the radio base station 102 will be described with reference to FIGS. 5 and 6.
  • an example using an open-loop transmission diversity scheme is shown as an open-loop transmission scheme. Instead, an open-loop spatial multiplexing transmission scheme is used. Is possible.
  • the radio base station 102 executes data communication in the continuous transmission operation mode with the radio terminal 104 to be transmitted.
  • the communication control unit 402 controls data communication in the continuous transmission operation mode with the radio terminal 104.
  • the communication control unit 402 applies both the open-loop transmission diversity scheme and the closed-loop spatial multiplexing transmission scheme to the data signal transmitted to the wireless terminal 104.
  • the communication control unit 402 determines and determines the allocation of radio resources (frequency band / frequency position allocated for signal transmission) in the uplink to the radio terminal 104 to be transmitted.
  • UL (Uplink) radio resource allocation information is generated based on the radio resource allocation.
  • the UL radio resource allocation information is control information indicating radio resource allocation in the uplink for each radio terminal 104 to transmit the above feedback signal to the radio base station 102.
  • an amount of radio resources corresponding to the amount of feedback signal information in the case of the closed-loop spatial multiplexing transmission scheme described later is allocated. It is done.
  • the communication control unit 402 generates a UL radio resource allocation signal based on the generated UL radio resource allocation information by controlling the encoding processing unit 404-4 and the modulation processing unit 410, and generates the generated UL radio resource allocation signal. Is subjected to modulation processing.
  • the RF transmission / reception unit 412 transmits the modulated signal to the wireless terminal 104 via the antenna unit 414.
  • the RF transmission / reception unit 412 receives a feedback signal including information on an evaluation report of downlink radio characteristics from the radio terminal 104 to be transmitted.
  • the radio terminal 104 transmits a feedback signal to the radio base station 102 based on the radio resource allocated in step S504.
  • the communication control unit 402 controls the demodulation / decoding processing unit 416 to generate feedback information based on the feedback signal received by the RF transmission / reception unit 412.
  • the communication control unit 412 receives the generated feedback information, and acquires information on an evaluation report of downlink radio characteristics.
  • step S ⁇ b> 508 the communication control unit 402 determines that the wireless terminal existing in the wireless cell 106 covered by the wireless base station 102 from management information (not shown) regarding the wireless terminal 104 held in the wireless base station 102. 104 pieces of information are acquired.
  • step S510 the communication control unit 402 determines whether or not to switch the PDSCH transmission mode to the transmission target wireless terminal 104 from the continuous transmission operation mode to the intermittent transmission operation mode.
  • the communication control unit 402 determines whether to switch the operation mode from the continuous transmission operation mode to the intermittent transmission operation mode according to the number of wireless terminals 104 present in the wireless cell 106 acquired in step S508. For example, when the number of acquired wireless terminals 104 is greater than a predetermined value, the communication control unit 402 determines to switch the operation mode from the continuous transmission operation mode to the intermittent transmission operation mode.
  • the intermittent transmission operation mode is applied to the operation mode, the process proceeds to step S512.
  • the intermittent transmission operation mode is not applied, the process proceeds to step S514.
  • step S512 when the communication control unit 402 determines to switch the transmission mode of the PDSCH to the transmission target wireless terminal 104 to the intermittent transmission operation mode, the communication control unit 402 generates intermittent transmission operation mode information.
  • the intermittent transmission operation mode control information includes information indicating that the intermittent transmission operation mode is applied, information on an occurrence period of an On-duration subframe in which a data signal is transmitted in the intermittent transmission operation mode, and an On-duration subframe.
  • the communication control unit 402 designates predetermined values as the generation period of the On-duration subframe and the threshold value related to the generation period.
  • the communication control unit 402 generates an intermittent transmission operation mode control signal based on the generated intermittent transmission operation mode control information by controlling the encoding processing unit 404-3 and the modulation processing unit 410, and generates the generated intermittent transmission operation. Modulation processing is performed on the mode control signal.
  • the RF transmission / reception unit 412 transmits the modulated signal to the wireless terminal 104 via the antenna unit 414.
  • step S514 the radio base station 102 continues data communication in the continuous transmission operation mode with the radio terminal 104 to be transmitted.
  • the communication control unit 402 continuously executes data communication control with the wireless terminal 104 in the continuous transmission operation mode.
  • step S516 the communication control unit 402 determines whether or not the current subframe type is the On-duration subframe specified in step S512 in the downlink radio section. If the current subframe type is an On-duration subframe, the process proceeds to step S518; otherwise, the process proceeds to step S520.
  • step S5128 when the communication control unit 402 determines that the current subframe type is an on-duration subframe, the generation period of the on-duration subframe specified in step S512 is greater than the specified threshold value. Determine whether it is long or not. If the generation period of the On-duration subframe is longer than the threshold, the process proceeds to step S524. If the generation period of the On-duration subframe is equal to or less than the threshold, the process proceeds to step S530.
  • the communication control unit 402 determines in step S520 that the current subframe type is not an on-duration subframe, the communication control unit 402 does not generate data and corresponding PDCCH for the wireless terminal 104 to be transmitted. That is, the radio base station 102 does not transmit the data signal and the corresponding PDCCH to the radio terminal 104.
  • step S524 the communication control unit 402 changes the radio resource allocation in the uplink performed in step S504.
  • the communication control unit 402 determines that the generation period of the specified On-duration subframe is longer than the specified threshold, thereby allowing the wireless terminal 104 that is present in the wireless cell 106 covered by the wireless base station 102 to It is determined that the number exceeds a certain allowable value, and the degree of congestion of the wireless terminal 104 in the wireless cell 106 has exceeded a certain allowable level. Thereby, the communication control unit 402 determines to apply only the open loop transmission diversity scheme to the data signal transmitted to the wireless terminal 104.
  • the communication control unit 402 determines to reduce the allocation of the radio resource (frequency band allocated for signal transmission) performed in step S504. That is, the communication control unit 402 is assigned radio resources in an amount corresponding to the information amount of the feedback signal in the case of the open-loop transmission diversity method described later. This is because in order to increase the number of radio terminals 104 that can be accommodated in the radio cell 106, it is necessary to reduce the amount of radio resources allocated per radio terminal.
  • the communication control unit 402 reduces the amount of radio resources allocated to the radio terminal 104 for transmission of the feedback signal to about half of the amount allocated in step S504.
  • both the open-loop transmission diversity scheme and the closed-loop spatial multiplexing transmission scheme are applied. This is because the amount of information of the feedback signal received from the wireless terminal 104 is about half that of the case.
  • the communication control unit 402 generates UL (Uplink) radio resource allocation information for the radio terminal 104 to be transmitted based on the changed radio resource allocation in the uplink.
  • the communication control unit 402 generates a UL radio resource allocation signal based on the generated UL radio resource allocation information, and transmits the generated UL radio resource allocation signal to the radio terminal 104, as in step S504.
  • step S526 the communication control unit 402, in step S524, the number of the wireless terminals 104 existing in the wireless cell 106 exceeds a certain allowable value, and the congestion level of the wireless terminals 104 in the wireless cell 106 is a certain allowable level.
  • the communication control unit 402 determines to apply only the open-loop transmission diversity scheme to the data signal transmitted to the wireless terminal 104.
  • the wireless terminal 104 to be transmitted recognizes that only the open-loop transmission diversity scheme is applied to the data signal transmitted from the wireless base station 102. Therefore, the RF transmission / reception unit 412 receives a feedback signal including information on a desired value of the modulation scheme and coding rate applied to the transmitted data signal from the wireless terminal 104 to be transmitted. At this time, the RF transmission / reception unit 412 does not receive information on the spatial multiplexing number (rank) and the desired value of the spatial code matrix as a feedback signal.
  • the communication control unit 402 controls the demodulation / decoding processing unit 416, and based on the received feedback signal, feedback including information on the desired value of the modulation scheme and coding rate applied to the transmitted data signal. Get information. As a result, the communication control unit 402 acquires the value of the modulation scheme / coding rate desired by the transmission target wireless terminal 104 for the transmitted data signal.
  • the information amount of the feedback signal transmitted from the wireless terminal 104 to the wireless base station 102 is 10 bits per subband, and the information amount of the desired value of the modulation scheme / coding rate is 4 bits. It is.
  • step S528, the communication control unit 402 controls the encoding processing units 404-5 and 404-6 and the modulation processing unit 410 based on the desired value of the modulation scheme / coding rate acquired in step S526. As a result, a data signal transmitted to the wireless terminal 104 and a corresponding PDCCH are generated. Then, the communication control unit 402 controls the modulation processing unit 410 and the RF transmission / reception unit 412 to convert the generated data signal and PDCCH into a signal of a format corresponding to the open-loop transmission diversity method, and then transmit the data signal. Transmit to the target wireless terminal 104. Transmission of the data signal and the PDCCH is performed in the same radio subframe regarding the same radio carrier.
  • the communication control unit 402 employs, for example, SFBC diversity as an open loop transmission diversity method. Further, the communication control unit 402 determines the transmission parameters of the open loop transmission diversity scheme without referring to the acquired feedback information.
  • Steps S526 and S528 correspond to the second transmission mode of processing in the radio base station 102.
  • step S530 the communication control unit 402 determines that the generation period of the designated On-duration subframe is equal to or less than the designated threshold value, so that the number of radio terminals 104 existing in the radio cell 106 is constant. It is determined that the congestion level of the wireless terminal 104 in the wireless cell 106 is below a certain allowable level. Thereby, the communication control unit 402 determines to apply both the open-loop transmission diversity scheme and the closed-loop spatial multiplexing transmission scheme to the data signal transmitted to the wireless terminal 104.
  • the transmission target wireless terminal 104 recognizes that both the open-loop transmission diversity scheme and the closed-loop spatial multiplexing transmission scheme are applied to the data signal transmitted from the wireless base station 102. Therefore, the RF transmission / reception unit 412 receives information on the desired value of the modulation scheme and coding rate applied to the data signal transmitted from the wireless terminal 104 to be transmitted, information on the desired value of the spatial multiplexing number (rank), and the space. A feedback signal including information on a desired value of the code matrix is received.
  • the communication control unit 402 controls the demodulation / decoding processing unit 416, and based on the received feedback signal, information on the desired value of the modulation scheme / coding rate applied to the transmitted data signal, spatial multiplexing Feedback information including information on the desired value of the number (rank) and information on the desired value of the spatial code matrix is acquired. As a result, the communication control unit 402 acquires the modulation scheme / coding rate, spatial multiplexing number (rank), and spatial code matrix values desired by the transmission target wireless terminal 104 for the transmitted data signal.
  • the information amount of the feedback signal transmitted from the wireless terminal 104 to the wireless base station 102 is 10 bits per subband.
  • the information amount of the desired value of the modulation scheme and coding rate is 4 bits
  • the information amount of the desired value of the spatial multiplexing number is 2 bits
  • the information amount of the spatial code matrix is 4 bits.
  • step S532 the communication control unit 402 controls the encoding processing units 404-5 and 404-6 and the modulation processing unit 410 based on the desired value of the modulation scheme / coding rate acquired in step S530. As a result, a data signal transmitted to the wireless terminal 104 and a corresponding PDCCH are generated.
  • the communication control unit 402 when transmitting the generated data signal and PDCCH by the closed loop spatial multiplexing transmission scheme, the communication control unit 402, based on the desired number of the spatial multiplexing number and spatial code matrix acquired in step S530, the modulation processing unit 410 and By controlling the RF transmission / reception unit 412, the generated data signal and PDCCH are converted into a signal in a format corresponding to the closed-loop spatial multiplexing transmission method, and then transmitted to the wireless terminal 104 to be transmitted.
  • the communication control unit 402 controls the modulation processing unit 410 and the RF transmission / reception unit 412 so that the generated data signal and PDCCH are closed loop.
  • the signal is converted into a signal in a format corresponding to the type spatial multiplexing transmission method, and then transmitted to the wireless terminal 104 to be transmitted.
  • the communication control unit 402 employs, for example, SFBC diversity as the open-loop transmission diversity scheme, and determines the transmission parameters of the open-loop transmission diversity scheme without referring to the acquired feedback information.
  • Steps S530 and S532 correspond to the first transmission mode of processing in the radio base station 102.
  • step S534 after transmitting the data signal and the PDCCH to the wireless terminal 104 in step S528 or S532, the communication control unit 402 needs to update the intermittent transmission operation mode control information for the wireless terminal 104 to be transmitted. Determine whether. When it is necessary to update the intermittent transmission operation mode control information, the communication control unit 402 controls the encoding processing unit 404-3 and the modulation processing unit 410 based on the updated intermittent transmission operation mode control information. An intermittent transmission operation mode control signal is generated, and modulation processing is performed on the generated intermittent transmission operation mode control signal. The RF transmission / reception unit 412 transmits the modulated signal to the wireless terminal 104 via the antenna unit 414.
  • step S536 If the updated intermittent transmission operation mode control signal is not transmitted, the process returns to step S516.
  • step S524 the communication control unit 402 determines whether to maintain the intermittent transmission operation mode as the transmission mode of the PDSCH to the transmission target wireless terminal 104.
  • the communication control unit 402 indicates that the intermittent transmission operation mode is canceled when the intermittent transmission operation mode is not maintained as the operation mode, that is, when it is determined to switch the operation mode from the intermittent transmission operation mode to the continuous transmission operation mode.
  • Intermittent transmission operation mode control information including information is generated. For example, the communication control unit 402 acquires information on the number of wireless terminals 104 existing in the wireless cell 106 based on the feedback information, and the acquired number of wireless terminals 104 is less than a predetermined value. At this time, it is decided to cancel the intermittent transmission operation mode.
  • the communication control unit 402 determines whether to change the generation period of the On-duration subframe.
  • the communication control unit 402 decides to change the generation period of the On-duration subframe, the communication control unit 402 generates an update value of the generation period of the On-duration subframe, and intermittent transmission operation including information of the generated update value Generate mode control information.
  • the communication control unit 402 applies, for example, the number of wireless terminals 104 to which the intermittent transmission operation mode is applied or the intermittent transmission operation mode from management information (not illustrated) related to the wireless terminal 104 held in the wireless base station 102.
  • the information such as the amount of data traffic for the wireless terminal 104 is acquired, and the generation period of the On-duration subframe is adaptively determined based on the acquired information. For example, when the number of wireless terminals 104 to which the intermittent transmission operation mode is applied increases, the communication control unit 402 lengthens the generation cycle of the On-duration subframe corresponding to each wireless terminal 104. Further, for example, when the amount of data traffic for the wireless terminal 104 to which the intermittent transmission operation mode is applied decreases, the communication control unit 402 increases the generation period of the On-duration subframe corresponding to each wireless terminal 104.
  • the communication control unit 402 determines whether or not to change the threshold related to the generation period of the On-duration subframe.
  • the communication control unit 402 decides to change the threshold value related to the generation cycle of the On-duration subframe, the communication control unit 402 generates information on the update value of the threshold value related to the generation cycle of the On-duration subframe, and the generated update value Including intermittent transmission operation mode control information is generated.
  • the communication control unit 402 determines the number of wireless terminals 104 to which the intermittent transmission operation mode is applied, the number of reception antennas of the wireless terminal 104, the wireless base station 102, from management information (not shown) held in the wireless base station 102. Information about the load state of the current sub-frame is acquired, and a threshold for the generation period of the On-duration subframe is adaptively determined based on the acquired information. For example, when the number of wireless terminals 104 to which the intermittent transmission operation mode is applied increases, the communication control unit 402 decreases the threshold regarding the generation period of the On-duration subframe corresponding to each wireless terminal 104.
  • step S536 the communication control unit 402 cancels the intermittent transmission operation mode as the transmission mode of the PDSCH to the transmission target wireless terminal 104 based on the intermittent transmission operation mode control information updated in step S534, and sets the operation mode. It is determined whether or not to switch to the continuous transmission operation mode. If the intermittent transmission operation mode is cancelled, the process proceeds to step S538. If the intermittent transmission operation mode is not cancelled, the process returns to step S516.
  • step S538 the radio base station 102 shifts to the continuous transmission operation mode with respect to the PDSCH transmission mode, and performs data communication in the continuous transmission operation mode with the wireless terminal 104 to be transmitted.
  • the communication control unit 402 controls data communication in the continuous transmission operation mode with the wireless terminal 104 to be transmitted.
  • step S536 When the intermittent transmission operation mode is not canceled in step S536 and the process returns to step S516, the update value of the generation period of the On-duration subframe generated in step S534 and the generation period are related. Based on the updated value of the threshold value, the processing from step S516 is executed again.
  • the intermittent transmission operation mode is applied to the data signal transmitted to the radio terminal 104, and the open-loop transmission scheme (open-loop transmission diversity scheme) is applied.
  • the radio base station 102 receives the desired value of the modulation scheme and coding rate as feedback information from the radio terminal 104, and does not receive the desired value of the spatial multiplexing number and the spatial code matrix.
  • the amount of information of the feedback signal can be reduced to about half compared to the case where a closed-loop transmission scheme (closed-loop spatial multiplexing transmission scheme) is applied.
  • the radio base station 102 can suppress the amount of radio resources in the uplink allocated to the radio terminal 104 for transmitting a feedback signal to about half.
  • the radio base station 102 can accommodate the radio signal without increasing the total amount of radio resources for transmitting a feedback signal.
  • the number of wireless terminals 104 can be increased.
  • FIG. 7 is a functional block diagram illustrating the configuration of the wireless terminal 104 according to the first embodiment.
  • the portion indicated by a thick solid line indicates that a plurality of information including data and various control information is transmitted.
  • the wireless terminal 104 includes a communication control unit 702, a multiplexing unit 704, a modulation / coding processing unit 706, an RF transmission / reception unit 708, an antenna unit 710, a PDCCH demodulation unit 712, a demodulation processing unit 714, a pilot.
  • a signal extraction unit 716, a decoding processing unit 718, and a wireless characteristic evaluation unit 720 are included.
  • the RF transmission / reception unit 708 receives a data signal and various control signals from the radio base station 102 via the antenna unit 710 including a plurality of antennas by PDSCH.
  • the RF transmission / reception unit 708 outputs the received data signal and control signal to the demodulation processing unit 714.
  • Control signals received by the PDSCH include a UL radio resource assignment signal, an intermittent transmission operation mode control signal, and a common control signal.
  • the RF transmission / reception unit 708 receives a PDCCH corresponding to the data signal from the radio base station 102 via the antenna unit 710 including a plurality of antennas using the PDCCH.
  • the RF transmission / reception unit 708 outputs the received PDCCH to the PDCCH demodulation unit 712 and the pilot signal extraction unit 716.
  • the PDCCH demodulation unit 712 receives the PDCCH from the RF transmission / reception unit 708. PDCCH demodulation section 712 performs demodulation processing on the received PDCCH under the control of communication control section 702, and outputs a signal obtained by the demodulation processing to demodulation processing section 714 and decoding processing section 718.
  • the pilot signal extraction unit 716 receives the PDCCH from the RF transmission / reception unit 708. Pilot signal extraction section 716 extracts a pilot signal included in the received PDCCH under the control of communication control section 702, and outputs the extracted pilot signal to radio characteristic evaluation section 720.
  • Radio characteristic evaluation unit 720 receives a pilot signal from pilot signal extraction unit 716. Based on the received pilot signal, the radio characteristic evaluation unit 720 evaluates radio characteristics of the downlink (downlink communication from the radio base station 102 to the radio terminal 104), and communicates information on the evaluation results of the downlink radio characteristics. The data is output to the control unit 702. Further, the radio characteristic evaluation unit 720 evaluates the maximum spatial multiplexing number that can be adopted by the radio terminal 104 based on the downlink radio characteristic evaluation result, and transmits information on the evaluation result of the spatial multiplexing number to the communication control unit. Output to 702. A. The demodulation processing unit 716 receives a data signal and various control signals received by the PDSCH from the RF transmission / reception unit 708.
  • the demodulation processing unit 716 refers to the result of the demodulation processing of the PDCCH demodulation unit 712 and the pilot signal extracted by the pilot signal extraction unit 716 under the control of the communication control unit 702, and converts the received data signal and control signal into The demodulating process is performed, and the signal obtained by the demodulating process is output to the decoding processing unit 718.
  • the decoding processing unit 718 performs decoding processing on the signal obtained by the demodulation processing of the PDCCH demodulation unit 712.
  • the decoding processing unit 718 generates link control information by decoding processing, and outputs the generated link control information to the communication control unit 702.
  • the decoding processing unit 718 performs decoding processing on the signal obtained by the demodulation processing of the demodulation processing unit 714.
  • the decoding processing unit 718 generates UL radio resource allocation information, intermittent transmission operation mode control information, and common control information by decoding processing, and outputs the generated link control information to the communication control unit 702.
  • the decoding processing unit 718 generates data by decoding processing, and outputs the generated data to the communication control unit 702.
  • the communication control unit 702 receives link control information, UL radio resource allocation information, intermittent transmission operation mode control information, and common control information from the decoding processing unit 718. Based on the received link control information, UL radio resource allocation information, intermittent transmission operation mode control information, and common control information, the communication control unit 702 receives the RF transmission / reception unit 708, the PDCCH demodulation unit 712, the demodulation processing unit 714, and the modulation / The operation of the encoding processing unit 706 is controlled.
  • the communication control unit 702 receives information on the evaluation result of the downlink radio characteristic and information on the evaluation result of the spatial multiplexing number from the radio characteristic evaluation unit 720.
  • the communication control unit 702 generates a downlink radio characteristic evaluation report based on the received downlink radio characteristic evaluation result, and outputs the generated downlink radio characteristic evaluation report to the multiplexing unit 704.
  • the communication control unit 702 generates modulation scheme / coding rate information indicating a desired modulation scheme / coding rate desired by the wireless terminal 104 based on the received downlink radio characteristic evaluation result, Modulation scheme / coding rate information is output to multiplexing section 704.
  • the communication control unit 702 based on the downlink radio characteristic evaluation result and the spatial multiplexing number evaluation result, the spatial multiplexing number information indicating the desired value of the spatial multiplexing number desired by the wireless terminal 104, and the spatial code matrix Spatial code matrix information indicating a desired value is generated, and the generated spatial multiplexing number information and spatial code matrix information are output to multiplexing section 704.
  • the downlink radio characteristic evaluation result, modulation scheme / coding rate information, spatial multiplexing number information, and spatial code matrix information generated by the communication control unit 702 are feedback information from the radio terminal 104 to the radio base station 102. .
  • the communication control unit 702 generates data to be transmitted to the radio base station 102 and outputs the generated data to the multiplexing unit 704.
  • the multiplexing unit 704 receives, from the communication control unit 702, feedback information and data including a downlink radio characteristic evaluation result, modulation scheme / coding rate information, spatial multiplexing number information, and spatial code matrix information.
  • the multiplexing unit 704 outputs the received feedback information and data to the modulation / coding processing unit 706, respectively.
  • the modulation / coding processing unit 706 performs coding processing and modulation processing on the output signal from the multiplexing unit 704 under the control of the communication control unit 702.
  • the modulation / coding processing unit 706 generates a feedback signal by performing coding processing and modulation processing on the feedback information, and outputs the generated feedback signal to the RF transmission / reception unit 708.
  • the modulation / coding processing unit 706 generates a data signal by performing coding processing and modulation processing on the data, and outputs the generated data signal to the RF transmission / reception unit 708.
  • the RF transceiver unit 708 transmits the output signal received from the modulation / coding processing unit 706 to the radio base station 102 via the antenna unit 710 including a plurality of antennas.
  • FIG. 8 and 9 are flowcharts for explaining a communication control method in the wireless terminal 104.
  • FIGS. 8 and 9 a communication control method performed in the wireless terminal 104 will be described with reference to FIGS. 8 and 9.
  • an example using an open-loop transmission diversity scheme is shown as an open-loop transmission scheme. Instead, an open-loop spatial multiplexing transmission scheme is used. Is possible.
  • step S802 the wireless terminal 104 performs data communication in the continuous transmission operation mode with the wireless base station 102.
  • the communication control unit 702 controls data communication in the continuous transmission operation mode with the wireless base station 102.
  • the communication control unit 702 applies both the open loop transmission diversity scheme and the closed loop spatial multiplexing transmission scheme to the data signal received from the radio base station 102.
  • the RF transceiver unit 708 receives an UL (Uplink) radio resource allocation signal from the radio base station 102.
  • the communication control unit 702 controls the demodulation processing unit 714 and the decoding processing unit 718 to generate UL radio resource allocation information based on the received UL radio resource allocation signal, and acquires the generated UL radio resource allocation information.
  • the UL radio resource allocation information is control information indicating radio resource allocation in the uplink for the radio terminal 104 to transmit the above feedback signal to the radio base station 102.
  • the communication control unit 702 sets information on radio resources allocated for transmission of feedback signals indicated by the acquired UL radio resource allocation information.
  • step S806 the communication control unit 702 generates a downlink radio characteristic evaluation report based on the evaluation result of the downlink radio characteristic received from the radio characteristic evaluation unit 720.
  • the communication control unit 702 controls the modulation / coding processing unit 706 to generate a feedback signal including information on the downlink radio characteristic evaluation report based on the generated downlink radio characteristic evaluation report.
  • the RF transmission / reception unit 708 transmits a feedback signal including information on the downlink radio characteristic evaluation report to the radio base station 102 based on the radio resource acquired in step S804 under the control of the communication control unit 702. .
  • step S808 the communication control unit 702 determines whether or not the RF transmission / reception unit 708 has received an intermittent transmission operation mode signal from the radio base station 102. If the intermittent transmission operation mode signal is received, the process proceeds to step S810. If the intermittent transmission operation mode signal is not received, the process proceeds to step S812.
  • step S810 when the RF transmission / reception unit 708 receives the intermittent transmission operation mode signal, the communication control unit 702 controls the demodulation processing unit 714 and the decoding processing unit 718 to intermittently operate based on the received intermittent transmission operation mode signal.
  • Transmission operation mode control information is generated, and the generated intermittent transmission operation mode information is acquired.
  • the intermittent transmission operation mode information includes information indicating that the intermittent transmission operation mode is applied, information on the generation period of the On-duration subframe, and information on threshold values regarding the generation period of the On-duration subframe.
  • the communication control unit 702 recognizes that the PDSCH transmission mode from the radio base station 102 has been switched from the continuous transmission operation mode to the intermittent transmission operation mode based on the acquired intermittent transmission operation mode information. Further, the communication control unit 702 acquires information about the generation period of the On-duration subframe and the threshold value related to the generation period in the intermittent transmission operation mode based on the acquired intermittent transmission operation mode information, Set to.
  • step S812 the wireless terminal 104 continues data communication in the continuous transmission operation mode with the wireless base station 102.
  • the communication control unit 702 continues to control data communication in the continuous transmission operation mode with the wireless base station 102.
  • step S814 the communication control unit 702 determines whether the generation period of the On-duration subframe acquired in step S812 is longer than the acquired threshold value. If the generation period of the On-duration subframe is longer than the threshold, the process proceeds to step S816. If the generation period of the On-duration subframe is equal to or less than the threshold, the process proceeds to step S818.
  • step S816 the communication control unit 702 generates modulation scheme / coding rate information indicating a desired value of the modulation scheme / coding rate based on the evaluation result of the downlink wireless characteristics received from the wireless characteristic evaluation unit 720.
  • a feedback signal including the modulation method / coding rate information is generated based on the generated modulation method / coding rate information.
  • the RF transmission / reception unit 708 transmits the generated feedback signal to the radio base station 102 based on the radio resource acquired in step S804 under the control of the communication control unit 702.
  • the information amount of the feedback signal transmitted from the wireless terminal 104 to the wireless base station 102 is 10 bits per subband, and the information amount of the desired value of the modulation scheme / coding rate is 4 bits. It is.
  • step S818 the communication control unit 702 generates modulation scheme / coding rate information indicating a desired value of the modulation scheme / coding rate based on the downlink wireless characteristic evaluation result received from the wireless characteristic evaluation unit 720. . Further, the communication control unit 702, based on the downlink radio characteristic evaluation result and the spatial multiplexing number evaluation result received from the radio characteristic evaluation unit 720, spatial multiplexing number information indicating a desired value of the spatial multiplexing number, and space Spatial code matrix information indicating a desired value of the code matrix is generated.
  • the communication control unit 702 controls the modulation / coding processing unit 706 so that the modulation scheme / coding rate information, spatial multiplexing number information, and spatial code matrix information are generated based on the generated modulation scheme / coding rate information, spatial code matrix information, A feedback signal including spatial multiplexing number information and spatial code matrix information is generated.
  • the RF transmission / reception unit 708 transmits the generated feedback signal to the radio base station 102 based on the radio resource acquired in step S804 under the control of the communication control unit 702.
  • the information amount of the feedback signal transmitted from the wireless terminal 104 to the wireless base station 102 is 10 bits per subband.
  • the information amount of the desired value of the modulation scheme and coding rate is 4 bits
  • the information amount of the desired value of the spatial multiplexing number is 2 bits
  • the information amount of the spatial code matrix is 4 bits.
  • step S820 the communication control unit 702 determines whether or not the current subframe type is an On-duration subframe in the downlink radio section. If the current subframe type is an On-duration subframe, the process proceeds to step S822; otherwise, the process proceeds to step S824.
  • step S822 when the communication control unit 702 determines that the current subframe type is an on-duration subframe, the generation period of the on-duration subframe acquired in step S810 is greater than the acquired threshold value. Determine whether it is long or not. If the generation period of the On-duration subframe is longer than the threshold, the process proceeds to step S826. If the generation period of the On-duration subframe is equal to or less than the threshold, the process proceeds to step S834.
  • step S824 if the communication control unit 702 determines that the type of the current subframe is not an on-duration subframe, the communication control unit 702 does not monitor the PDCCH transmitted from the radio base station 102 in the current subframe. . That is, the wireless terminal 104 does not receive the data signal and the corresponding PDCCH from the wireless base station 102.
  • step S826 the communication control unit 702 determines that the generation period of the On-duration subframe is longer than the threshold value, so that the number of wireless terminals 104 existing in the wireless cell 106 covered by the wireless base station 102 is constant. It is determined that the congestion level of the wireless terminal 104 in the wireless cell 106 has exceeded a certain allowable level. Accordingly, the communication control unit 702 recognizes that only the open loop transmission diversity scheme is applied to the data signal to be transmitted in the radio base station 102.
  • the communication control unit 702 uses the RF transmission / reception unit 708 to monitor the reception of only the PDCCH corresponding to the open-loop transmission diversity scheme from the radio base station 102 by blind detection. At this time, the communication control unit 702 does not monitor whether or not the RF transmitting / receiving unit 708 has received the PDCCH corresponding to the closed-loop spatial multiplexing transmission method.
  • the PDCCH controls information indicating the frequency band and frequency position in the radio subframe of the corresponding data signal, information indicating the modulation scheme and coding rate applied to the data signal, and retransmission operation of the data signal.
  • HARQ Hybrid Automatic repeat request
  • step S830 when a PDCCH corresponding to the open-loop transmission diversity scheme is detected as a result of monitoring the PDCCH in step S826, the RF transceiver unit 708 receives a data signal corresponding to the detected PDCCH. .
  • the communication control unit 702 generates and acquires data based on the received data signal by controlling the demodulation processing unit 714 and the decoding processing unit 718 based on the detected PDCCH.
  • step S 832 the RF transceiver unit 708 receives a UL radio resource allocation signal from the radio base station 102.
  • the communication control unit 702 controls the demodulation processing unit 714 and the decoding processing unit 718 to generate UL radio resource allocation information based on the received UL radio resource allocation signal, and acquires the generated UL radio resource allocation information. .
  • the communication control unit 702 uses the radio resource information indicated by the acquired UL radio resource allocation information to set internal setting information.
  • the radio base station 102 halves the amount of radio resources allocated to transmission of feedback signals, for example, corresponding to applying only the open-loop transmission diversity scheme to the transmitted data signal. change.
  • both the open-loop transmission diversity scheme and the closed-loop spatial multiplexing transmission scheme are applied. This is because the amount of information of the feedback signal transmitted by the wireless terminal 104 is about half that of the case.
  • Steps S816 and S826 to S832 correspond to the second reception mode of processing in the wireless terminal 104.
  • step S834 the communication control unit 702 determines that the generation period of the On-duration subframe is equal to or less than the threshold value, so that the number of wireless terminals 104 existing in the wireless cell 106 covered by the wireless base station 102 is constant. It is determined that the congestion level of the wireless terminal 104 in the wireless cell 106 is below a certain allowable level. Thereby, the communication control unit 702 recognizes that both the open-loop transmission diversity scheme and the closed-loop spatial multiplexing transmission scheme are applied to the data signal to be transmitted in the radio base station 102.
  • the communication control unit 702 uses the RF transmission / reception unit 708 to blindly detect reception of both the PDCCH corresponding to the open loop transmission diversity scheme and the PDCCH corresponding to the closed loop spatial multiplexing transmission scheme from the radio base station 102. Monitor.
  • step S836 when one of the PDCCH corresponding to the open loop transmission diversity scheme and the PDCCH corresponding to the closed loop spatial multiplexing transmission scheme is detected as a result of the monitoring of the PDCCH in step S834, the RF transmission / reception unit 708 Receives a data signal corresponding to the detected PDCCH.
  • the communication control unit 702 generates and acquires data based on the received data signal by controlling the demodulation processing unit 714 and the decoding processing unit 718 based on the detected PDCCH.
  • Steps S818, S834, and S836 correspond to the first reception mode of processing in the wireless terminal 104.
  • step S838 the communication control unit 702 has received an intermittent transmission operation mode control signal from the radio base station 102 in the RF transceiver unit 708 after receiving the data signal from the radio base station 102 in step S830 or S836. Confirm whether or not.
  • the communication control unit 702 controls the demodulation processing unit 714 and the decoding processing unit 718 to thereby perform intermittent transmission operation mode control information based on the received intermittent transmission operation mode control signal. And the generated intermittent transmission operation mode control information is acquired.
  • the communication control part 702 determines whether the acquired intermittent transmission operation mode control information differs from the intermittent transmission operation mode control information acquired in step S810. That is, the communication control unit 702 determines whether or not the updated intermittent transmission operation mode control signal is received from the radio base station 102.
  • the acquired intermittent transmission operation mode control information includes, for example, information indicating that the intermittent transmission operation mode is canceled, an update value of the generation period of the On-duration subframe, or an update value of a threshold value related to the generation period.
  • step S840 If the updated intermittent transmission operation mode control signal is not received, the process returns to step S814.
  • step S840 the communication control unit 702 determines whether or not the intermittent transmission operation mode control information acquired in step S838 includes information indicating that the intermittent transmission operation mode is released. That is, the communication control unit 702 determines whether or not the radio base station 102 can cancel the intermittent transmission operation mode as the PDSCH transmission mode and switch the operation mode to the continuous transmission operation mode.
  • step S842 If the intermittent transmission operation mode is cancelled, the process proceeds to step S842. If the intermittent transmission operation mode is not cancelled, the process returns to step S814.
  • step S842 the wireless terminal 104 shifts to the continuous transmission operation mode with respect to the PDSCH transmission mode from the wireless base station 102, and executes data communication in the continuous transmission operation mode with the wireless base station 102.
  • the communication control unit 702 controls data communication in the continuous transmission operation mode with the radio base station 102.
  • step S840 When the intermittent transmission operation mode is not canceled in step S840 and the process returns to step S814, the generation period of the On-duration subframe included in the intermittent transmission operation mode control signal acquired in step S838 is determined. Based on the updated value and the updated value of the threshold related to the generation cycle, the processes in and after step S814 are executed again.
  • the wireless terminal 104 when the intermittent transmission operation mode is applied to the data signal to be transmitted and the open loop transmission scheme (open loop transmission diversity scheme) is applied.
  • the data signal transmitted from the radio base station 102 by the open loop transmission method is received. Therefore, the wireless terminal 104 only needs to detect the PDCCH corresponding to the open-loop transmission scheme when receiving the data signal, and the PDCCH corresponding to the closed-loop transmission scheme (closed-loop spatial multiplexing transmission scheme). Therefore, the number of processes in receiving a data signal can be reduced, and power consumption in receiving a data signal can be reduced.
  • FIG. 10 is a hardware configuration diagram illustrating an example of the configuration of the radio base station 102 and the radio terminal 104.
  • Each of the wireless base station 102 and the wireless terminal 104 includes a processor 1002, a memory 1004, a storage device 1006, a wireless communication interface 1008, a bus 1010, and an antenna 1012.
  • the processor 1002, the memory 1004, the storage device 1006, and the wireless communication interface 108 are each connected to the bus 1010.
  • the functions of the functional blocks of the radio base station 102 shown in FIG. 4 can be realized by the hardware configuration shown in FIG.
  • the memory 1004 is, for example, a RAM.
  • the storage device 1006 is, for example, a nonvolatile memory such as a ROM or a flash memory, or a magnetic disk device such as an HDD (Hard Disk Drive).
  • the functions and processes can be realized by the processor 1002 executing a processing program describing the corresponding functions and processes.
  • the processing program is stored in the storage device 1006.
  • the processor 1002 expands the processing program stored in the storage device 1006 in the memory 1004, and executes each processing described in the processing program, so that the processing program is shown in FIG. Each functional block described above is realized.
  • the above-described functional blocks shown in FIG. 4 are realized by LSIs such as ASIC (Application Specified Integrated Circuit) and FPGA (Field Programmable Gate Array). Also good.
  • LSIs such as ASIC (Application Specified Integrated Circuit) and FPGA (Field Programmable Gate Array). Also good.
  • the RF transmission / reception unit 412 and the antenna unit 414 shown in FIG. 4 can be realized by the wireless communication interface 1008 and the antenna 1012.
  • the wireless communication interface 1008 is, for example, an LSI such as an RF IC (Radio Frequency Integrated Circuit).
  • the antenna 1012 includes a plurality of antennas.
  • the wireless communication interface 1008 receives a digital signal from the bus 1010, converts the received digital signal into an analog wireless signal, and transmits the converted wireless signal to the wireless terminal 104 via the antenna 1012.
  • the wireless communication interface 1008 receives an analog wireless signal via the antenna 1012, converts the received wireless signal into a digital signal having a frequency that can be processed by the processor 1002, and sends the converted digital signal to the bus 1010. Output.
  • the functions of the functional blocks of the wireless terminal 104 shown in FIG. 7 can be realized by the hardware configuration shown in FIG.
  • the memory 1004 is, for example, a RAM.
  • the storage device 1006 is, for example, a nonvolatile memory such as a ROM or a flash memory, or a magnetic disk device such as an HDD (Hard Disk Drive).
  • the function and processing of each functional block can be realized by the processor 1002 executing a processing program describing the corresponding function and processing.
  • the processing program is stored in the storage device 1006.
  • the processor 1002 expands the processing program stored in the storage device 1006 in the memory 1004, and executes each processing described in the processing program, so that the processing program is shown in FIG. Each functional block described above is realized.
  • the above-described functional blocks shown in FIG. 7 are realized by an LSI such as ASIC (Application Specified Integrated Circuit) or FPGA (Field Programmable Gate Array). Also good.
  • ASIC Application Specified Integrated Circuit
  • FPGA Field Programmable Gate Array
  • the RF transmission / reception unit 708 and the antenna unit 710 shown in FIG. 7 can be realized by the wireless communication interface 1008 and the antenna 1012.
  • the wireless communication interface 1008 is, for example, an LSI such as an RF IC (Radio Frequency Integrated Circuit).
  • the antenna 1012 includes a plurality of antennas.
  • the wireless communication interface 1008 receives a digital signal from the bus 1010, converts the received digital signal into an analog wireless signal, and transmits the converted wireless signal to the wireless terminal 104 via the antenna 1012.
  • the wireless communication interface 1008 receives an analog wireless signal via the antenna 1012, converts the received wireless signal into a digital signal having a frequency that can be processed by the processor 1002, and sends the converted digital signal to the bus 1010. Output.
  • the open-loop transmission diversity scheme is used as the open-loop transmission scheme, but an open-loop spatial multiplexing transmission scheme is used instead. Also good.
  • the wireless terminal 104 adds a desired value of the spatial multiplexing number as feedback information, and sends it to the wireless base station 102.
  • a feedback signal including the desired value of the spatial multiplexing number is transmitted.
  • a predetermined value is used in the radio base station 102.
  • the open loop transmission diversity method is used as the open loop transmission method. Instead, the radio base station 102 performs intermittent transmission to the PDSCH.
  • the wireless terminal 104 may be instructed which transmission method to apply, the open loop transmission diversity method or the open loop spatial multiplexing transmission method.
  • the radio base station 102 uses the open-loop transmission diversity scheme or the open-loop type as the intermittent transmission operation mode control information. Instruction information indicating which transmission system of the spatial multiplexing transmission system is applied is added, and an intermittent transmission operation mode signal including the instruction information is transmitted to the wireless terminal 104.
  • one threshold is used as the threshold for the generation period of the On-duration subframe, but instead, two thresholds are used as the threshold for the generation period. You may do it.
  • the radio base station 102 performs an open loop transmission diversity scheme, an open loop spatial multiplexing scheme, and a closed loop on the PDSCH.
  • Three transmission schemes of type spatial multiplexing are applied. That is, the radio base station 102 applies the closed-loop spatial multiplexing scheme when the generation period of the On-duration subframe is equal to or less than the first threshold, and when the generation period is longer than the first threshold, Apply spatial multiplexing. Further, the radio base station 102 applies the open-loop transmission diversity scheme when the generation period of the On-duration subframe is longer than the second threshold having a value larger than the first threshold.
  • the amount of information of the feedback signal transmitted from the wireless terminal 104 to the wireless base station 102 in the open-loop spatial multiplexing scheme is smaller than the closed-loop spatial multiplexing transmission because it does not include information on the desired value of the spatial code matrix.
  • the amount is larger than that of the open-loop transmission diversity method, because it includes information on the desired value of the spatial multiplexing number.
  • the amount of radio resources allocated per radio terminal is reduced. Since it can be reduced in stages, the number of radio terminals that can be accommodated in the radio cell 106 by the radio base station 102 is increased while suppressing deterioration in communication quality from the radio base station 102 to the radio terminal 104. be able to.
  • the radio base station 102 determines to apply the intermittent transmission operation mode to the PDSCH and further to apply the open-loop transmission method
  • the wireless terminal 104 is periodically notified to the wireless base station 102 including the desired value of the modulation scheme and coding rate, while notifying the instruction information indicating that the desired value of the spatial code matrix is not notified. It may be.
  • the radio base station 102 uses the generation period of the On-duration subframe as the intermittent transmission operation mode control information.
  • the desired value of the modulation scheme and coding rate is included in the feedback information, while the desired value of the spatial code matrix is not included, and the feedback information is periodically included.
  • Instruction information indicating transmission is added, and an intermittent transmission operation mode signal including the instruction information is transmitted to the wireless terminal 104.
  • radio base station first radio station
  • second wireless terminal second wireless station
  • 402 communication control unit 404-1 to 6-6 encoding processing unit
  • 406-1 2 multiplex part
  • 408 time multiplexing part 410 modulation processing unit, 412 RF transceiver, 414 antenna section, 416 demodulation / decoding processing unit, 702 communication control unit, 704 Multiplexer, 706 modulation / coding processing unit, 708 RF transceiver, 710 antenna part, 712 PDCCH demodulator, 714 demodulation processing unit, 716 pilot signal extraction unit, 718 decryption processing unit, 720 wireless characteristic evaluation unit, 1002 processor, 1004 memory, 1006 storage device, 1008 Wireless communication interface, 1010 bus, 1012 Antenna

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  • Engineering & Computer Science (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Signal Processing (AREA)
  • Mobile Radio Communication Systems (AREA)

Abstract

L'invention concerne un système de communication sans fil comprenant une première station sans fil, et une pluralité de secondes stations sans fil qui reçoivent les données provenant de la première station sans fil, en fonction d'une pluralité de formats de transmissions nécessitant différents volumes d'informations de rétroaction pour la transmission. Dans ce système de communication sans fil, la première station sans fil définit, dans une première période, une trame de communication parmi une pluralité de trames de communication, pour effectuer la transmission de données vers les secondes stations sans fil. En fonction de la longueur de la première période, les différentes secondes stations sans fil évaluent le facteur de congestion de la pluralité de secondes stations sans fil dans la première station sans fil.
PCT/JP2012/002744 2012-04-20 2012-04-20 Station sans fil et système de communication sans fil WO2013157046A1 (fr)

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PCT/JP2012/002744 WO2013157046A1 (fr) 2012-04-20 2012-04-20 Station sans fil et système de communication sans fil

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PCT/JP2012/002744 WO2013157046A1 (fr) 2012-04-20 2012-04-20 Station sans fil et système de communication sans fil

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Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2001044900A (ja) * 1999-05-28 2001-02-16 Texas Instr Inc <Ti> 複数の送信アンテナを有し開ループおよび閉ループ送信ダイバーシチを結合する無線システム
WO2006030916A1 (fr) * 2004-09-17 2006-03-23 Ntt Docomo, Inc. Procédé de communication mobile, station mobile et station de base
JP2007049367A (ja) * 2005-08-09 2007-02-22 Ntt Docomo Inc 移動通信システムの制御方法、制御装置、移動通信システム

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2001044900A (ja) * 1999-05-28 2001-02-16 Texas Instr Inc <Ti> 複数の送信アンテナを有し開ループおよび閉ループ送信ダイバーシチを結合する無線システム
WO2006030916A1 (fr) * 2004-09-17 2006-03-23 Ntt Docomo, Inc. Procédé de communication mobile, station mobile et station de base
JP2007049367A (ja) * 2005-08-09 2007-02-22 Ntt Docomo Inc 移動通信システムの制御方法、制御装置、移動通信システム

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Title
MITSUBISHI ELECTRIC: "Comaprison of closed-loop antenna selection with open-loop transmit deversity (antenna switching within a TTI)", 3GPP R1-070523, 15 January 2007 (2007-01-15) *
NORTEL: "Open-loop Adaptive Antenna Switching for UL MIMO", 3GPP R1-070448, 15 January 2007 (2007-01-15) *

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