JP2018186540A - Terminal device, radio communications system, control method, and program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a technique when determining one cell to which a PUCCH has to be transmitted in a Dual Connectivity.SOLUTION: When a terminal device is connected to a first base station device and a second base station device, the terminal device notifies of information on a wireless quality in regards to a signal received from the second base station device in one or more frequency band of a plurality of frequency bands to the first base station device; and acquires the information indicating the frequency band to which a control channel has to be transmitted from the first base station device. The frequency band to which the control channel has to be transmitted is a frequency band selected by the second base station device from the frequency bands extracted as a frequency band in which the wireless quality exceeds a predetermined value from the plurality of frequency bands by the first base station device, and is indicated to the second base station device.SELECTED DRAWING: Figure 6

Description

  The present invention relates to a radio communication system including a plurality of base station apparatuses and terminals that communicate with the plurality of base station apparatuses.

  In the 3rd Generation Partnership Project (3GPP), installing many small cells (small cells) that use different frequency bands (for example, higher frequency bands than those used in macro cells) within the coverage of large cells (macro cells) Has been discussed. For example, as in the example of FIG. 1, a plurality of small cells using the 3.5 GHz band frequency band are placed in the coverage area of the macro cell using the 2 GHz band frequency band.

  In LTE Release 12, discussions have begun on a technique called Dual Connectivity in which two types of base stations cooperate in such an environment (Non-Patent Document 1). The two types of base stations are a master eNodeB (master eNB, eg, a macro cell base station) and a secondary eNodeB (secondary eNB, eg, a small cell base station). In Dual Connectivity, the two types of base stations are connected by a wired or wireless backhaul line. In addition, a terminal device can establish a connection between both the master eNB and the secondary eNB, and can receive data from, for example, two base station devices.

  In Dual Connectivity, the master eNB performs signaling of a control signal in the downlink direction to the terminal device (Non-Patent Document 1). On the other hand, in the uplink, it is assumed that the control signal from the terminal is transmitted not only to the master eNB but also to the secondary eNB. Here, the master eNB and the secondary eNB can use a plurality of frequency bands each having a certain bandwidth, and the terminal device transmits a control signal in at least one of the plurality of frequency bands. To do. Each of the plurality of frequency bands corresponds to, for example, a component carrier having a 20 MHz bandwidth. In addition, for example, a separate baseband unit is allocated to each of a plurality of frequency bands that can be used by the master eNB and the secondary eNB, and a separate cell (communication range) is formed in each of the plurality of frequency bands. The Rukoto. That is, each of the master eNB and the secondary eNB is one base station apparatus, but forms a plurality of cells corresponding to a plurality of frequency bands. The set of the plurality of cells for the master eNB is called an MCG (Master Cell Group), and the set of the plurality of cells for the secondary eNB is called an SCG (Secondary Cell Group).

3GPP TR 36.842 v12.0.0

  The terminal device must transmit a control channel (PUCCH, physical uplink control channel) to the master eNB and the secondary eNB in one cell of the MCG and one cell of the SCG. For this reason, it is necessary for the master eNB and the secondary eNB to determine and notify the cell to which the terminal device must transmit the control channel.

  Regarding this, at the 3GPP meeting, there is an agreement that a secondary eNB decides one cell for which a PUCCH among a plurality of cells included in the SCG must be transmitted for a certain terminal device. . At this time, it is also agreed that the secondary eNB may receive assistance from the master eNB. However, a specific method has not been established regarding what kind of assistance the secondary eNB receives from the master eNB and how to select the one cell described above.

  This invention is made | formed in view of the said subject, and it aims at providing the method at the time of determining one cell in which PUCCH should be transmitted in Dual Connectivity.

  The terminal device according to one aspect of the present invention transmits a control channel from the terminal device to the second base station device when the terminal device is connected to the first base station device and the second base station device. A radio communication system in which the second base station apparatus selects a power frequency band from a plurality of frequency bands that can be used by the second base station apparatus, and the selected frequency band is notified to the terminal apparatus The terminal device according to claim 1, wherein the first base station device is related to a radio quality related to a signal received from the second base station device for one or more frequency bands of the plurality of frequency bands. Notification means for notifying information, and acquisition means for acquiring information indicating the frequency band to which the control channel is to be transmitted from the first base station apparatus, wherein the control channel transmits The frequency band to be transmitted is extracted as a frequency band in which the radio quality of the plurality of frequency bands exceeds a predetermined value by the first base station apparatus and notified to the second base station apparatus The frequency band selected by the second base station apparatus from among the above.

  A terminal device according to another aspect of the present invention transmits a control channel from the terminal device to the second base station device when the terminal device is connected to the first base station device and the second base station device. A radio in which the second base station apparatus selects a frequency band to be performed from a plurality of frequency bands that can be used by the second base station apparatus, and the selected frequency band is notified to the terminal apparatus In the communication system, the terminal device is a radio relating to a signal received from the second base station device for the one or more frequency bands of the plurality of frequency bands to the first base station device. Notification means for notifying information on quality, and acquisition means for acquiring information indicating the frequency band to which the control channel is to be transmitted from the first base station apparatus, wherein the control channel The frequency band to be transmitted is a predetermined number of frequencies extracted from the higher one of the plurality of frequency bands by the first base station apparatus and notified to the second base station apparatus The frequency band is selected by the second base station apparatus from the band.

  ADVANTAGE OF THE INVENTION According to this invention, the method at the time of determining one cell in which PUCCH should be transmitted in Dual Connectivity is provided.

The conceptual diagram which shows the example of arrangement | positioning of the macro cell and small cell which each use a different frequency band. The conceptual diagram which shows the example of communication between the terminal and multiple eNB by Dual Connectivity. The figure which shows the hardware structural example of the master eNB and the secondary eNB. The block diagram which shows the function structural example of the master eNB. The block diagram which shows the function structural example of secondary eNB. The sequence diagram which shows the example of the flow of a process.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

(System configuration)
The radio communication system according to the present embodiment includes, for example, a master eNB, a secondary eNB, and a terminal device (UE) as illustrated in FIG. Here, eNB is a base station apparatus (eNodeB), but the corresponding radio communication system may be other than LTE. Also, the terminal device is a mobile or fixed wireless communication device, and may correspond to a wireless communication system other than LTE. Note that in the wireless communication system of the present embodiment, the master eNB performs communication using a first frequency band (for example, 2 GHz), and the secondary eNB performs communication using a second frequency band (3.5 GHz). The master eNB and the secondary eNB may be able to use the same frequency band, that is, the first frequency band and the second frequency band may be the same frequency band. Note that the first frequency band and the second frequency band may exist as partial frequency bands within the same frequency band, such as a 2 GHz band, for example, even if they are different frequency bands.

  The master eNB and the secondary eNB can perform communication using a plurality of component carriers (CC) in the frequency band used by each. Each of the plurality of CCs corresponds to a frequency band having a certain width such as 20 MHz. In addition, as described above, the master eNB and the secondary eNB form a plurality of communicable cells for each of the plurality of CCs. Thus, since one cell corresponds to one CC, the word “cell” is used below including the meaning of the corresponding CC (frequency band). In the following discussion, the frequency band corresponding to each cell does not necessarily correspond to one CC, and may correspond to a frequency band having a predetermined bandwidth defined in the wireless communication system.

  As described above, a set of cells formed by the master eNB is called an MCG (Master Cell Group), while a set of cells formed by the secondary eNB is called an SCG (Secondary Cell Group). In FIG. 2, the MCG and the SCG each include five cells. This number is determined based on, for example, the frequency bandwidth that can be used by the master eNB and the secondary eNB and the frequency bandwidth of one CC. Communication is performed between the master eNB and the terminal using at least one cell of the MCG. Similarly, in a state in which Dual Connectivity is established, communication is performed between the secondary eNB and the terminal using at least one cell of the SCG.

  In Dual Connectivity, communication on the C-plane (control plane) such as transmission of an RRC (Radio Resource Control) message transmitted to the terminal is performed by the master eNB and not by the secondary eNB. A cell in which communication between the master eNB and the terminal in such a control plane is performed is called a PCell. In PCell, in addition to communication on the control plane, communication on the U-plane (user plane) can also be performed. Also, the PCell is set for each terminal. For example, it is ensured that the terminal can transmit uplink data to the master eNB in the PCell set for itself. In addition, although a terminal can also transmit uplink data in another cell, for example, it does not transmit data in another cell without transmitting data in the set PCell. In addition, the terminal must transmit PUCCH (Physical Uplink Control Channel) in the PCell. In addition, the terminal measures the radio quality of the radio signal transmitted from the master eNB or the secondary eNB for one or more of the cells included in the MCG and the cells included in the SCG, and the measurement result is mastered in the PCell. The eNB can be notified. The radio quality may be, for example, reference signal received power (RSRP) or reference signal received quality (RSRQ), but other radio quality (for example, SIR, SNR, etc.) may be used as the radio quality. Note that the terminal may notify the measurement result to the master eNB when a predetermined condition is satisfied, for example, when a radio signal from an SCG cell is received at a predetermined power or higher, for example, periodically. Such a measurement result may be notified to the master eNB. In addition, the MCG includes, for example, a downlink serving cell for the terminal, and the master eNB can transmit data to the terminal in the downlink serving cell.

  On the other hand, in SCG, a cell for transmitting an RRC message is not set as in PCell, but a cell in which a PUCCH should be transmitted by a terminal is set for each terminal. Here, this cell is called a primary SCell (pSCell). In addition, although a terminal can also transmit PUCCH also in cells other than pSCell, it is not necessary to transmit PUCCH in cells other than pSCell, but it must transmit PUCCH in pSCell. The SCG also includes a downlink serving cell, for example, like the MCG, and can transmit data to the terminal in the downlink serving cell. In addition, not all cells need to be used for communication with the terminal in MCG and SCG. For example, as shown by a blank rectangle in FIG. 2, any of PCell, pSCell, and downlink serving cell Some cells do not fall under. And the master eNB and the secondary eNB do not perform communication with a terminal in such a cell, for example.

(Overview)
As described above, the PCell and the pSCell are selected and set from the MCG and the SCG, respectively, for each terminal, and the setting information is notified to the terminal by, for example, the RRC message via the master eNB. And about pSCell, as mentioned above, the secondary eNB selects from SCG, and the agreement is formed in 3GPP. At this time, the secondary eNB may make this selection using the assist information notified from the master eNB. However, a specific method for this selection and what information should be used as assist information are not determined at present.

  For this reason, below, the selection method of pSCell with the assistance of the master eNB by the concrete secondary eNB is proposed.

(Configuration of master eNB and secondary eNB)
FIG. 3 shows a hardware configuration example of the master eNB and the secondary eNB (base station apparatus) according to the present embodiment. The master eNB and the secondary eNB include, for example, a CPU 301, a ROM 302, a RAM 303, an external storage device 304, and a communication device 305. In the master eNB and the secondary eNB, for example, the CPU 301 executes a program that realizes the functions of the master eNB and the secondary eNB as described below, which are recorded in any of the ROM 302, the RAM 303, and the external storage device 304.

  Then, the master eNB and the secondary eNB, for example, control the communication device 305 by the CPU 301 to perform communication between the master eNB and secondary eNB and the terminal, or inter-eNB communication between the master eNB and the secondary eNB. Note that the master eNB and the secondary eNB may be provided with dedicated hardware for executing each function, or may be executed by a computer that executes a part of the hardware and executes the program. Further, all functions may be executed by a computer and a program.

  In FIG. 3, the master eNB and the secondary eNB are assumed to have one communication device 305, but actually there may be a plurality of communication devices 305, and the communication device 305 includes a plurality of communication devices. It may be configured. That is, for example, the master eNB and the secondary eNB may include a communication device for communication between eNBs and a communication device for communication with terminals.

  Moreover, the master eNB and the secondary eNB may prepare a communication device for communication with a terminal for each CC. Note that the communication device 305 may include a plurality of units for baseband processing, and may be configured to transmit signals in a plurality of CCs generated by them using one antenna. In that case, for example, by assigning identification information (global ID) that uniquely identifies the unit, one CC for one eNB can be identified by the global ID. Note that a cell ID may be assigned for each frequency band (CC). In this case, one CC for one eNB is specified by specifying two identification information of a cell ID and an ID for specifying an eNB. Can be specified.

  Next, the functional configuration of the master eNB will be described. FIG. 4 is a block diagram illustrating a functional configuration example of the master eNB according to the present embodiment. The master eNB includes, for example, a wireless communication unit 401, a wired communication unit 402, a wireless quality information acquisition unit 403, and an assist information generation unit 404.

  The wireless communication unit 401 is a functional unit for performing wireless communication, and performs wireless communication by establishing a wireless connection with a terminal, for example. That is, the wireless communication unit 401 establishes a connection with a terminal in one or more of a plurality of cells included in the MCG. And the radio | wireless communication part 401 selects one cell as PCell among one or more cells which establish a connection, for example, and notifies a terminal with a RRC message. The terminal recognizes the PCell that should transmit the PUCCH according to the RRC message. And the wireless communication part 401 receives PUCCH from a terminal in PCell. In addition, the wireless communication unit 401 transmits data to the terminal in the PCell or, for example, a downlink serving cell. Further, the wireless communication unit 401 receives data from the terminal in the PCell or in other cells. The wireless communication unit 401 can further receive a measurement report (Measurement Report) including information such as reference signal reception power (RSRP) or reference signal reception quality (RSRQ) from the terminal. The received measurement report is input to the radio quality information acquisition unit 403.

  The wired communication unit 402 is a functional unit for performing wired communication. For example, the wired communication unit 402 establishes connection with the secondary eNB and performs wired communication. For example, the wired communication unit 402 notifies the secondary eNB of the assist information when the secondary eNB selects the pSCell, which is generated by the assist information generation unit 404 described later. Note that the master eNB and the secondary eNB may be connected via a fixed wireless line, for example, instead of a wired line. In this case, the wired communication unit 402 may not be provided. In addition, when there is a wireless section in the middle of the connection between the master eNB and the secondary eNB, the wired communication unit 402 exists to establish a wired connection with the end point of the wireless section in the middle. Good.

  The radio quality information acquisition unit 403 acquires information related to the radio quality of the radio signal received by the terminal for one or more cells included in the plurality of cells included in the SCG received by the radio communication unit 401. That is, the radio quality information acquisition unit 403 acquires, for example, RSRP or RSRQ information as radio quality information in the terminal. This wireless quality information is acquired for each terminal. The acquired wireless quality information is input to the assist information generation unit 404.

  The assist information generation unit 404 generates assist information based on the wireless quality information. The generated assist information is transmitted to the secondary eNB via the wired communication unit 402. For example, the assist information generation unit 404 generates assist information including radio quality information for each of the cells for which radio quality information has been acquired from a certain terminal. In this case, cell identification information and radio quality information are associated with each other and included in the assist information in order to clearly indicate what radio quality is obtained in which cell. Note that the assist information is generated separately for each of a plurality of terminals, for example. Note that the assist information generation unit 404 may form a signal in which the assist information corresponding to a plurality of terminals is integrated into one and transmit the signal to the secondary eNB via the wired communication unit 402.

  For example, the assist information generation unit 404 extracts a part of a plurality of cells included in the SCG as candidate cells that the secondary eNB should select as the pSCell based on the radio quality information. 405 may be further included.

  For example, based on the radio quality information, candidate cell extraction unit 405 extracts a predetermined number of cells from the higher radio quality among the plurality of cells included in the SCG as the partial cells described above. Further, for example, based on the radio quality information, candidate cell extraction unit 405 may extract, as a part of the cells, cells whose radio quality exceeds a predetermined value among a plurality of cells included in the SCG. . Furthermore, at this time, candidate cell extraction section 405 may selectively extract a predetermined number of cells when the number of cells whose radio quality exceeds a predetermined value exceeds a predetermined number. At this time, for example, the candidate cell extraction unit 405 may randomly select and extract a predetermined number of cells from cells whose radio quality exceeds a predetermined value, or, for example, select from a higher radio quality. A number of cells may be selected and extracted.

  The assist information generation unit 404 generates assist information by including information for specifying some extracted cells. The information specifying this cell is, for example, identification information for identifying each cell in the secondary eNB. In this case, by transmitting identification information about a certain cell to the secondary eNB, the one cell in the secondary eNB can be specified by a combination of the destination and the identification information. Similarly, the information for specifying the cell may include the identification information of the secondary eNB and the cell identification information. Thus, a certain cell in a certain secondary eNB can be uniquely specified by the combination of the identification information of the secondary eNB and the identification information of the cell. Furthermore, when different IDs are assigned to each cell of each eNB and there is identification information that can uniquely identify an arbitrary cell in an arbitrary eNB, the identification information is used as information for specifying the cell. May be. For example, a global ID for uniquely identifying the unit is assigned to the baseband processing unit for each cell. For this reason, this global ID can be used as information for specifying a cell.

  The assist information generation unit 404 may include the information for identifying the extracted part of cells in the assist information in the order according to the rank of the radio quality. For example, among the five cells, the first cell, the second cell, and the fourth cell are extracted as the above-mentioned partial cells, and the radio quality thereof is the fourth cell, the first cell, A case where it is the second cell will be described. In this case, the assist information generation unit 404 includes, in the assist information, information for specifying cells in the order of “4”, “1”, and “2”, for example. When receiving this information, the secondary eNB can grasp that the fourth cell has the best radio quality, and subsequently the radio quality of the first cell and the second cell decreases. . Therefore, for example, the secondary eNB may select the fourth cell as a cell in which the terminal must transmit the PUCCH because the fourth cell is considered to be a cell with the highest PUCCH reception quality. it can. Note that the assist information generation unit 404 may include, for example, information that identifies cells in the order of “2”, “1”, and “4” in the assist information. Also in this case, the secondary eNB has received this information, so that the fourth cell has the best radio quality, and subsequently, the radio quality of the first cell and the second cell decreases. Can be grasped.

  Note that the assist information generation unit 404 may generate assist information by adding information about the order of the ranks of radio quality for the extracted cells. For example, in the above-described case, the assist information generation unit 404 adds information “2” for the first cell, “3” for the second cell, and “1” for the fourth cell. It may be generated. Further, the assist information may include, for example, a field that includes information on the rank of radio quality for each cell, and the assist information generation unit 404 stores the numerical value of the rank in this field, Assist information may be generated. That is, for example, the assist information generation unit 404 sets “2” in the field for the first cell, “3” in the field for the second cell, “1” in the field for the fourth cell, Each may be stored to generate assist information. Note that the assist information generation unit 404 may store “0” in a field for a cell with a rank after a predetermined number, for example.

  Further, the assist information generation unit 404 may generate assist information including radio quality information for some extracted cells. That is, for example, among the five cells, when the first cell, the second cell, and the fourth cell are extracted as some of the cells described above, for example, the value of RSRP or RSRQ for these cells is Included and assist information is generated. A value other than RSRP or RSRQ may be used as the radio quality. In this case, since the rank of the radio quality becomes clear on the basis of the radio quality information, the above-described rank information need not be included, but this information may also be included. This is because the master eNB may not know how the secondary eNB uses the assist information.

  Subsequently, the functional configuration of the secondary eNB will be described. FIG. 5 is a block diagram illustrating a functional configuration example of the secondary eNB according to the present embodiment. The secondary eNB includes, for example, a wireless communication unit 501, a wired communication unit 502, an assist information acquisition unit 503, and a pSCell selection unit 504.

  The wireless communication unit 501 is a functional unit for performing wireless communication, and performs wireless communication by establishing a wireless connection with a terminal, for example. That is, the wireless communication unit 501 establishes a connection with a terminal in one or more of a plurality of cells included in the SCG. And the radio | wireless communication part 501 receives PUCCH from a terminal in pSCell, for example in one cell which the pSCell selection part 504 selected among one or more cells which establish a connection. Further, the radio communication unit 501 transmits data to the terminal in the pSCell or the serving cell for downlink. Further, the wireless communication unit 501 receives data from the terminal in the pSCell or in addition to the other cell.

  The wired communication unit 502 is a functional unit for performing wired communication. For example, the wired communication unit 502 establishes a connection with the master eNB and performs wired communication. For example, the wired communication unit 502 receives data such as assist information transmitted from the master eNB. Note that the master eNB and the secondary eNB may be connected not by a wired line but by a wireless line such as a wireless entrance, for example. In this case, the wired communication unit 502 may not be provided. In addition, when there is a wireless section in the middle of the connection between the master eNB and the secondary eNB, even if the wired communication unit 502 exists to establish a wired connection with the end point of the wireless section in the middle Good.

  The assist information acquisition unit 503 acquires assist information from a signal from the master eNB received via the wired communication unit 502, for example. The acquired assist information is input to the pSCell selection unit 504. Note that the assist information acquisition unit 503 may wait for assist information to arrive from the master eNB, but in some cases, a certain terminal may be specified and assist information about the terminal may be requested from the master eNB. Good.

  Based on the input assist information, the pSCell selection unit 504 selects a pSCell for a terminal corresponding to the assist information from a plurality of cells included in the SCG. The pSCell selection unit 504, for example, if the assist information includes information for identifying some of the cells extracted by the master eNB among the plurality of cells included in the SCG, the extracted one Select pSCell from the cell of the part. Moreover, the pSCell selection part 504 may select the cell with the highest radio | wireless quality as pSCell, for example, when the order of the radio | wireless quality about the one part cell is shown in assist information. Here, the pSCell selection unit 504 selects, for example, a cell having the highest radio quality as a pSCell when the number of terminals having the cell as the pSCell is equal to or greater than a predetermined number. Also good.

  Further, when the assist information includes radio quality information such as RSRP or RSRQ value in each cell, the pSCell selection unit 504 has a cell whose radio quality value is a predetermined value or more. You may select pSCell from among. Further, the pSCell selection unit 504 may select the pSCell with priority from the cell with the highest wireless quality included in the assist information. That is, for the cell with the highest radio quality, when the number of terminals having the cell as a pSCell is a predetermined number or more, the cell with the next highest radio quality may be selected as the pSCell. When the terminal measures the radio quality for all cells of the SCG, all of the values may be included in the assist information. In this case as well, in order from the cell with the higher radio quality value, A cell having a quality value equal to or higher than a predetermined value may be selected as the pSCell.

  The information on the cell selected by the pSCell selection unit 504 is notified to the master eNB via the wired communication unit 502, for example. Note that the pSCell selection unit 504 may control the wireless communication unit 501 with the selected pSCell.

  When the master eNB receives the information on the selected cell via the wired communication unit 402, the master eNB generates an RRC message in order to set the pSCell, and transmits the generated RRC message to the terminal via the wireless communication unit 401. Send to.

(Process flow)
Then, the flow of the process which a master eNB, a secondary eNB, and a terminal each perform in a radio | wireless communications system is demonstrated. FIG. 6 is a sequence diagram illustrating an example of a flow of processing according to the present embodiment. In addition, at the time of the start of the process of FIG. 6, between the terminal and the master eNB, among the plurality of cells included in the MCG, the connection setting such as which cell becomes the PCell is completed. To do.

  In the process, first, the terminal observes radio signals received from the master eNB and the secondary eNB and measures radio quality (S601). Note that the radio quality measurement can be performed for one or more cells included in the MCG and one or more cells included in the SCG, but here, the radio quality of the cells included mainly in the SCG is mainly measured. It only needs to be measured. In addition, this measurement may be performed when a predetermined event occurs, for example, the terminal enters the range of any cell formed by the secondary eNB. It should be noted that the predetermined event is determined by the setting of the wireless communication system, and is obviously not limited to being in the range of any cell formed by the secondary eNB. Subsequently, the terminal notifies the master eNB of the radio quality measured for at least the SCG (S602). Note that the notification of the radio quality is performed in the PCell included in the MCG.

  When the master eNB acquires the radio quality information, the secondary eNB subsequently generates assist information for selecting the pSCell (S603). At this time, the assist information includes, for example, information for identifying a predetermined number of cells from the higher radio quality of the radio signal received at the terminal. Further, the assist information may be information that identifies a cell whose radio quality exceeds a predetermined value. Further, when there are a predetermined number or more of cells whose radio quality exceeds a predetermined value, the assist information may be information for specifying a predetermined number of cells selected from the cells. The information for specifying a cell can be as shown in the above-described examples, and can be, for example, a global ID for uniquely specifying a unit for baseband processing corresponding to the cell. In addition, when the information for specifying a plurality of cells is included in the assist information, the information for specifying the cells is included in the order according to the rank of the radio quality of those cells, and the assist information is generated. Also good. Moreover, assist information may be comprised by the value of the radio | wireless quality (for example, RSRP or RSRQ) measured by the terminal about each cell contained in SCG. In this case, for example, when the radio quality is not measured for some cells, the same value as that when the radio quality is the lowest value is included as the radio quality information for the some cells. Also good. Furthermore, the assist information includes radio quality information for a predetermined number of cells or cells whose radio quality exceeds a predetermined value as described above, and radio quality information for other cells may not be included. Thereafter, the master eNB notifies the generated assist information to the secondary eNB (S604).

  The secondary eNB uses the notified assist information to select a pSCell that is a cell to which the terminal must transmit the PUCCH (S605). Here, the secondary eNB does not necessarily need to use the notified assist information, and may or may not use the assist information depending on the case. For example, when the accuracy of the wireless quality information used when the assist information is generated is low, the secondary eNB may not use the information. In this case, the master eNB may determine the accuracy information according to, for example, the reception quality of the radio signal when the notification of the radio quality in S602 is performed, and notify the secondary eNB. Further, depending on the setting of the secondary eNB, it may be determined whether the secondary eNB uses or does not use the assist information notified from the master eNB.

  Note that this selection of pSCell may be performed again for a terminal for which pSCell has already been set. That is, based on the radio quality of the radio signal from each cell included in the SCG in each terminal, the above-described selection for resetting the pSCell in each terminal may be performed. At this time, the secondary eNB may also select cells (secondary SCell, sSCell) used for communication with the terminal.

  When the secondary eNB selects the pSCell, the secondary eNB notifies the master eNB of information indicating the selected pSCell (S606). In addition, when sSCell is determined by S605, you may notify the master eNB of the information which shows sSCell in this notification together. This notification can be transmitted as, for example, an inter-eNB RRC message (Inter eNB RRC message).

  When the master eNB receives notification of information indicating the pSCell for a certain terminal, the master eNB transmits an RRC message (for example, an RRCConnectionReconfiguration message) for wireless connection setting regarding the terminal (S607). By this message, information indicating the pSCell to which the terminal should transmit the PUCCH is notified to the terminal. Thereafter, the terminal performs wireless communication setting so as to transmit the PUCCH in the notified pSCell. Then, in response to the completion of the wireless connection setting, for example, the terminal transmits an RRCConnectionReconfigurationComplete message (S608), and ends this process.

  Thus, in this embodiment, the master eNB generates assist information that can be used when the secondary eNB selects a pSCell for the terminal based on the radio quality measured by the terminal. Then, the secondary eNB receives provision of this assist information from the master eNB and selects a pSCell based on the information. By such a method, it becomes possible to select pSCell so that the communication quality of PUCCH transmitted from a terminal to a secondary eNB becomes high.

Claims (10)

When the terminal device is connected to the first base station device and the second base station device, a frequency band in which a control channel is to be transmitted from the terminal device to the second base station device is set to the second base station. The terminal device in the wireless communication system in which the second base station device selects from a plurality of frequency bands that can be used by the station device, and the selected frequency band is notified to the terminal device,
Notifying means for notifying the first base station apparatus of information relating to radio quality related to a signal received from the second base station apparatus for one or more of the plurality of frequency bands;
Obtaining means for obtaining information indicating the frequency band in which the control channel is to be transmitted from the first base station apparatus;
Have
The frequency band in which the control channel is to be transmitted is extracted as a frequency band in which the radio quality of the plurality of frequency bands exceeds a predetermined value by the first base station apparatus, and the second base station apparatus The frequency band selected by the second base station device from the frequency band notified to
A terminal device characterized by that. When the frequency band in which the control channel is to be transmitted has more than a predetermined number of frequency bands in which the radio quality exceeds the predetermined value, the radio quality is set to the predetermined value by the first base station apparatus. Among the frequency bands that exceed, the predetermined number of frequency bands are extracted and notified to the second base station apparatus, and are selected from the predetermined number of frequency bands by the second base station apparatus ,
The terminal device according to claim 1. When the terminal device is connected to the first base station device and the second base station device, a frequency band in which a control channel is to be transmitted from the terminal device to the second base station device is set to the second base station. The terminal device in the wireless communication system in which the second base station device selects from a plurality of frequency bands that can be used by the station device, and the selected frequency band is notified to the terminal device,
Notifying means for notifying the first base station apparatus of information relating to radio quality related to a signal received from the second base station apparatus for one or more of the plurality of frequency bands;
Obtaining means for obtaining information indicating the frequency band in which the control channel is to be transmitted from the first base station apparatus;
Have
The frequency band to which the control channel is to be transmitted is extracted from the higher one of the plurality of frequency bands by the first base station apparatus and notified to the second base station apparatus The frequency band selected by the second base station device from a predetermined number of frequency bands,
A terminal device characterized by that. The information on the radio quality includes at least one of reference signal reception power and reference signal reception quality,
The terminal device according to claim 1, wherein: When the terminal device is connected to the first base station device and the second base station device, a frequency band in which a control channel is to be transmitted from the terminal device to the second base station device is set to the second base station. A radio communication system in which the second base station apparatus selects from among a plurality of frequency bands that can be used by the station apparatus, and the selected frequency band is notified to the terminal apparatus,
The terminal device is
First notifying means for notifying the first base station apparatus of information relating to radio quality regarding a signal received from the second base station apparatus for one or more of the plurality of frequency bands. When,
First acquisition means for acquiring information indicating the frequency band in which the control channel is to be transmitted from the first base station device;
Have
The first base station apparatus is
Second acquisition means for acquiring information on the wireless quality from the terminal device;
Extraction means for extracting a frequency band in which the radio quality exceeds a predetermined value of the plurality of frequency bands based on the information on the radio quality acquired by the second acquisition means;
Second notification means for notifying the second base station apparatus of information indicating the frequency band extracted by the extraction means;
Have
The second base station apparatus is
Third acquisition means for acquiring information indicating the frequency band extracted by the extraction means from the first base station apparatus;
Selection means for selecting the frequency band in which the control channel is to be transmitted based on the information acquired by the third acquisition means;
Third notification means for notifying the terminal device of the frequency band in which the control channel selected by the selection means is to be transmitted;
A wireless communication system comprising: When the terminal device is connected to the first base station device and the second base station device, a frequency band in which a control channel is to be transmitted from the terminal device to the second base station device is set to the second base station. A radio communication system in which the second base station apparatus selects from among a plurality of frequency bands that can be used by the station apparatus, and the selected frequency band is notified to the terminal apparatus,
The terminal device is
First notifying means for notifying the first base station apparatus of information relating to radio quality regarding a signal received from the second base station apparatus for one or more of the plurality of frequency bands. When,
First acquisition means for acquiring information indicating the frequency band in which the control channel is to be transmitted from the first base station device;
Have
The first base station apparatus is
Second acquisition means for acquiring information on the wireless quality from the terminal device;
Extraction means for extracting a predetermined number of frequency bands from a higher one of the plurality of frequency bands based on information on the radio quality acquired by the second acquisition means;
Second notification means for notifying the second base station apparatus of information indicating the frequency band extracted by the extraction means;
Have
The second base station apparatus is
Third acquisition means for acquiring information indicating the frequency band extracted by the extraction means from the first base station apparatus;
Selection means for selecting the frequency band in which the control channel is to be transmitted based on the information acquired by the third acquisition means;
Third notification means for notifying the terminal device of the frequency band in which the control channel selected by the selection means is to be transmitted;
A wireless communication system comprising: When the terminal device is connected to the first base station device and the second base station device, a frequency band in which a control channel is to be transmitted from the terminal device to the second base station device is set to the second base station. A control method for the terminal device in a wireless communication system in which the second base station device selects from a plurality of frequency bands that can be used by the station device and the selected frequency band is notified to the terminal device. And
A notification means for notifying the first base station apparatus of information relating to radio quality related to a signal received from the second base station apparatus for one or more of the plurality of frequency bands. Process,
An acquisition step of acquiring, from the first base station device, information indicating the frequency band to which the control channel is to be transmitted;
Have
The frequency band in which the control channel is to be transmitted is extracted as a frequency band in which the radio quality of the plurality of frequency bands exceeds a predetermined value by the first base station apparatus, and the second base station apparatus The frequency band selected by the second base station device from the frequency band notified to
A control method characterized by that. When the terminal device is connected to the first base station device and the second base station device, a frequency band in which a control channel is to be transmitted from the terminal device to the second base station device is set to the second base station. A control method for the terminal device in a wireless communication system in which the second base station device selects from a plurality of frequency bands that can be used by the station device and the selected frequency band is notified to the terminal device. And
A notification means for notifying the first base station apparatus of information relating to radio quality related to a signal received from the second base station apparatus for one or more of the plurality of frequency bands. Process,
An acquisition step of acquiring, from the first base station device, information indicating the frequency band to which the control channel is to be transmitted;
Have
The frequency band to which the control channel is to be transmitted is extracted from the higher one of the plurality of frequency bands by the first base station apparatus and notified to the second base station apparatus The frequency band selected by the second base station device from a predetermined number of frequency bands,
A control method characterized by that. When the terminal device is connected to the first base station device and the second base station device, a frequency band in which a control channel is to be transmitted from the terminal device to the second base station device is set to the second base station. A computer provided in the terminal device in a wireless communication system in which the second base station device selects from among a plurality of frequency bands that can be used by the station device, and the selected frequency band is notified to the terminal device In addition,
The first base station apparatus is notified of information on radio quality related to a signal received from the second base station apparatus for one or more frequency bands of the plurality of frequency bands,
From the first base station apparatus, information indicating the frequency band in which the control channel is to be transmitted is acquired.
A program for
The frequency band in which the control channel is to be transmitted is extracted as a frequency band in which the radio quality of the plurality of frequency bands exceeds a predetermined value by the first base station apparatus, and the second base station apparatus The frequency band selected by the second base station device from the frequency band notified to
A program characterized by that. When the terminal device is connected to the first base station device and the second base station device, a frequency band in which a control channel is to be transmitted from the terminal device to the second base station device is set to the second base station. A computer provided in the terminal device in a wireless communication system in which the second base station device selects from among a plurality of frequency bands that can be used by the station device, and the selected frequency band is notified to the terminal device In addition,
The first base station apparatus is notified of information on radio quality related to a signal received from the second base station apparatus for one or more frequency bands of the plurality of frequency bands,
From the first base station apparatus, information indicating the frequency band in which the control channel is to be transmitted is acquired.
A program for
The frequency band to which the control channel is to be transmitted is extracted from the higher one of the plurality of frequency bands by the first base station apparatus and notified to the second base station apparatus The frequency band selected by the second base station device from a predetermined number of frequency bands,
A program characterized by that.

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