JP2015216419A - Base station device, control method, and program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable a plurality of base station devices to set appropriate communication speed to a terminal device in dual connectivity.SOLUTION: Provided is a base station device in a radio communication system in which a terminal device connects to the base station device and another base station device, and the total of communication speed between the base station device and the terminal device and communication speed between the other base station device and the terminal device is limited to a certain value or below. The base station device determines whether an upper limit value of communication speed between the base station device and the terminal device reported by the other base station device should be readjusted, and requests the other base station device to readjust the upper limit value if it has determined that the upper limit value should be readjusted.

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 cell base station devices using a 3.5 GHz band frequency band are placed in a coverage area of a macro cell base station device using a 2 GHz band frequency band. The Here, the “cell” includes the concept of “sector”. Each base station apparatus is connected to a serving gateway (S-GW), and the terminal apparatus is connected to one base station apparatus. The S-GW establishes a communication link with the terminal device via the base station device. A communication link established between the S-GW and the terminal device via the base station device is referred to as a bearer here.

  In LTE Release 12, discussions have begun on a technique called Dual Connectivity in which two types of base station apparatuses cooperate in such an environment (Non-Patent Document 1). The two types of base station apparatuses are a master eNodeB (master eNB, for example, a macro cell base station) and a secondary eNodeB (secondary eNB, for example, a small cell base station). In Dual Connectivity, the two types of base station apparatuses 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 the LTE system, there is an index called UE-AMBR (Aggregate Maximum Bit Rate) as an index indicating the quality of communication (QoS (Quality of Service)) required by the terminal device (see Non-Patent Document 2). This indicator targets non-GBR (guaranteed bit rate) bearers of which the bit rate is not guaranteed among the bearers established between the S-GW and the terminal device, and is the sum of all non-GBR bearers established by the terminal device. Gives the upper limit of bit rate. This UE-AMBR is determined for each terminal device, for example, by a communication carrier. Based on this index, the base station device limits the amount of radio resources allocated to the terminal device.

3GPP TR 36.842 v12.0.0 3GPP TS 36.300 v12.1.0 3GPP R3-140938

  In Dual connectivity, since the terminal device communicates with the S-GW via the plurality of base station devices, it is an issue how the plurality of base stations cooperate to provide the upper limit of the bit rate by UE-AMBR. Become.

  In this regard, in 3GPP, it is agreed that the master eNB provides information for UE-AMBR to the secondary eNB (see Non-Patent Document 3). In this case, for example, the master eNB notifies the UE-AMBR value to be set by the secondary eNB, and the secondary eNB communicates with the corresponding terminal device according to the UE-AMBR. However, there is no guarantee that the UE-AMBR determined by the master eNB is an appropriate value, and in some cases, there is a problem that the terminal device may be excessively limited in communication speed.

  This invention is made | formed in view of the said subject, and aims at providing the technique for a master eNB and a secondary eNB to set an appropriate communication speed with respect to a terminal device in Dual Connectivity.

  In order to achieve the above object, a base station apparatus according to the present invention includes a terminal apparatus connected to a base station apparatus and another base station apparatus, and the terminal apparatus of the base station apparatus and the other base station apparatus, In the wireless communication system in which the total communication speed between the base station apparatus and the terminal apparatus is notified from the other base station apparatus in a wireless communication system in which the total communication speed is limited to a certain value or less. When the determination unit determines whether the upper limit value of the communication speed should be readjusted and the determination unit determines that the upper limit value should be readjusted, the readjustment of the upper limit value is performed by the other base station. Requesting means for requesting the apparatus.

  In order to achieve the above object, another base station device according to the present invention includes a terminal device connected to a base station device and another base station device, and the base station device and the other base station device, In the wireless communication system in which the total communication speed with the terminal device is limited to a certain value or less, the base station device to the other base station device and the other base station device and the terminal device A notification means for notifying an upper limit value of a communication speed between the base station apparatus, a receiving means for receiving a request for readjustment of the upper limit value from the other base station apparatus, and in response to receiving the request, Readjustment means for readjusting the upper limit value, and the notification means notifies the readjusted upper limit value to the other base station apparatus.

  ADVANTAGE OF THE INVENTION According to this invention, in Dual Connectivity, the master eNB and the secondary eNB can set an appropriate communication speed with respect to a terminal device.

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. In the wireless communication system according to 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). Can do. 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.

(Overview)
As illustrated in FIG. 2, in dual connectivity, the terminal device can establish a connection with the master eNB and the secondary eNB at the same time. And a terminal device can establish a communication link between a serving gateway (S-GW) through a master eNB and a secondary eNB. As described above, the communication link established by the S-GW with the terminal device via the base station device is called a bearer. A bearer can be classified into a bearer of GBR (Guaranteed Bit Rate) and a non-GBR bearer in which a communication speed (bit rate) is guaranteed, for example, with one service (FTP, HTTP, etc.) as a unit.

  As described above, UE-AMBR (Aggregate Maximum Bit Rate) is defined as an index for keeping the total communication speed below a certain value in 3GPP for non-GBR bearers where the communication speed is not guaranteed. . The fixed value is a value determined by the communication carrier for each terminal device or contract, for example. For example, when the UE-AMBR value is determined to be 1 Mbps for a certain terminal device, the bit rate for the Non-GBR bearer between the terminal device and the S-GW is suppressed to within 1 Mbps.

  In Dual Connectivity, in order to properly operate the UE-AMBR, the master eNB and the secondary eNB perform communication control so that the total value of communication speeds with the terminal device is equal to or less than the value indicated by the UE-AMBR. Will be performed. On the other hand, in 3GPP, the master eNB determines the UE-AMBR value to be set in the secondary eNB, notifies the secondary eNB, and the secondary eNB performs communication control based on the notified value. Assumed.

  It is assumed that the master eNB uses information on the radio quality between the secondary eNB and the terminal device, which is fed back from the terminal device, as a determination material for starting provision of Dual connectivity to the terminal device. And when the terminal device starts Dual connectivity based on the information, for example, the master eNB sets the UE-AMBR value of the secondary eNB high and sets the UE-AMBR value of the master eNB low. . For example, the master eNB sets the UE-AMBR of the master eNB to 256 kbps and the UE-AMBR of the secondary eNB to 768 kbps when the upper limit of the communication speed for a certain terminal device is 1 Mbps. At this time, if the communication speed that can be set with the terminal device corresponding to the notified UE-AMBR exceeds the value of the UE-AMBR, the secondary eNB restricts the communication speed, and the UE-AMBR Communication with the terminal device is performed at the indicated communication speed. On the other hand, since the master eNB knows its own communication status, the UE-AMBR value can be set within a settable communication speed range. For this reason, the master eNB can communicate with the terminal device at a communication rate indicated by UE-AMBR set for itself with a high probability. Thereby, the master eNB and the secondary at a communication speed that is equal to or lower than the upper limit value and close to the upper limit value by using the specific upper limit value of the communication speed of communication between the master eNB and the secondary eNB and the terminal device. Communication between eNB and a terminal device is attained.

  On the other hand, for example, when the secondary eNB side communicates with many terminal devices, the secondary eNB has a communication speed much lower than the UE-AMBR value for the terminal device. It may not be possible. This is because when the number of connected terminal devices is large, for example, the number of physical resource blocks that can be allocated to individual terminal devices can be limited. In this case, since the communication speed in the secondary eNB is low, the total value of the communication speeds between the master eNB and the secondary eNB and the terminal device can be significantly lower than the originally assumed upper limit value. That is, in the secondary eNB, when the communication speed as high as the UE-AMBR value set for the secondary eNB cannot be achieved, the communication is excessively higher than the upper limit value of the communication speed originally assumed for the terminal device. It can impose speed limitations.

  On the other hand, in this embodiment, the secondary eNB requests UE-AMBR readjustment to the master eNB when, for example, the UE-AMBR value cannot be satisfied in the actual communication environment. And the master eNB performs UE-AMBR readjustment, for example, UE-AMBR in the master eNB is increased and UE-AMBR in the secondary eNB is readjusted low. Thereby, the value of UE-AMBR of a master eNB and a secondary eNB is set appropriately, and an excessive communication speed limit is prevented from being imposed on the terminal device.

  Below, the structure of a specific master eNB and the secondary eNB and the flow of a process are demonstrated.

(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 each function of the master eNB and the secondary eNB as described below, which is 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. For example, the master eNB and the secondary eNB may include a wired communication device for communication between eNBs and a wireless communication device for communication with a terminal.

  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, and an upper limit determination unit 403.

  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. Note that the wireless communication unit 401 sets, for example, an upper limit value of the communication speed with the terminal device based on the UE-AMBR value determined by the upper limit value determination unit 403 described later, It communicates with the terminal device.

  The wired communication unit 402 is a functional unit for performing wired communication, and establishes connection between a network node such as S-GW and a secondary eNB, for example, and performs wired communication. For example, the wired communication unit 402 notifies the secondary eNB of UE-AMBR, which is the upper limit value of the communication speed between the secondary eNB and the terminal device, which is determined or readjusted by the upper limit value determination unit 403 described later. In addition, the wired communication unit 402 transfers data received from the terminal device by the wireless communication unit 401 to the S-GW, or transmits data transferred from the S-GW to the terminal device via the wireless communication unit 401. To do. Furthermore, for example, when communication data between the secondary eNB and the terminal device is transmitted / received via the master eNB, the wired communication unit 402 transfers the data from the secondary eNB to the S-GW. Note that the master eNB and the secondary eNB or S-GW may be connected by 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 or S-GW, the wired communication unit 402 establishes a wired connection with the end point of the wireless section in the middle May be present.

  The upper limit determination unit 403 holds, for example, information on the upper limit value of the communication speed (bit rate) for a certain terminal device, and determines the UE-AMBR value in the master eNB and the secondary eNB based on the information. For example, when starting to provide Dual Connectivity, the upper limit value determination unit 403, based on information on the radio quality of the radio signal received from the secondary eNB by the terminal device received by the radio communication unit 401, the UE- of the secondary eNB Determine the AMBR. Moreover, when the upper limit determination unit 403 receives a request for readjustment of the UE-AMBR from the secondary eNB via the wired communication unit 402, the communication speed between the master eNB and the secondary eNB and the terminal device Readjust the upper limit of.

  For example, when the upper limit of the total communication speed for a certain terminal device is 1 Mbps, the upper limit determination unit 403 initially sets the UE-AMBR for the master eNB to 256 kbps and the UE-AMBR for the secondary eNB to 768 kbps. decide. Then, the upper limit determination unit 403 notifies the secondary eNB of a value of 768 kbps as the UE-AMBR value via the wired communication unit 402. Thereafter, upon receiving a request for readjustment of the UE-AMBR value from the secondary eNB via the wired communication unit 402, the upper limit determination unit 403 receives the UE-AMBR of the master eNB and the secondary eNB according to the request. Readjust the value of. Here, the upper limit determination unit 403 also re-adjusts the value of the UE-AMBR of the master eNB in response to a request from the secondary eNB. The UE-AMBR of the master eNB and the secondary eNB in the corresponding terminal device This is because the sum of the values is a constant value. That is, for example, when the upper limit determination unit 403 decreases the UE-AMBR value of the secondary eNB to 512 kbps in response to the readjustment request, the UE-AMBR value of the master eNB is reduced to 512 kbps accordingly. Raise up. Thereby, the total value of UE-AMBR with respect to the target terminal apparatus becomes 1 Mbps, and the master eNB and the secondary eNB cooperate even after readjustment, whereby the upper limit value of the communication speed assumed for the terminal apparatus Can be achieved.

  When the upper limit determination unit 403 receives a request value for the UE-AMBR value from the secondary eNB along with the request for UE-AMBR readjustment via the wired communication unit 402, for example, the UE of the secondary eNB -Set the value of AMBR to its required value. The upper limit determination unit 403 may determine the value of the UE-AMBR of the secondary eNB with reference to the request value without setting the value of the UE-AMBR of the secondary eNB to the request value. For example, the upper limit determination unit 403 may use the intermediate value between the UE-AMBR value of the secondary eNB so far and the request value as the UE-AMBR value of the secondary eNB after readjustment.

  In addition, when the upper limit determination unit 403 receives an index indicating the load state in the secondary eNB from the secondary eNB via the wired communication unit 402 together with a request for UE-AMBR readjustment, the upper limit determination unit 403 The value of UE-AMBR may be readjusted. Here, the index indicating the state of the load can be, for example, at least one of the usage status of the physical resource block (PRB) in the secondary eNB or information on the terminal device connected to the secondary eNB.

  For example, the PRB usage information is used for all PRBs, PRB usage rate, PRB ratio used for bearers (GBR) for which communication speed is guaranteed, and Non-GBR bearers. It can be the ratio of PRB. Further, the information regarding the usage status of the PRB may be, for example, the number of unused (free) PRBs or the ratio of the number to all PRBs. The information about the terminal device connected to the secondary eNB is, for example, the number of terminal devices whose queue length is not 0, the average value of the number of terminal devices in a predetermined period, or the number of terminal devices that have established radio links. It is possible.

  Upon receiving the information on the load on the secondary eNB, the upper limit determination unit 403 compares the received information with the information on the load on the master eNB, for example. And the upper limit determination part 403 determines the ratio of the value of UE-AMBR between the master eNB and the secondary eNB according to the ratio of the value of the load, for example. For example, the upper limit determination unit 403 determines to decrease the UE-AMBR value for the eNB with the larger load. Thereby, it is possible to reduce the probability that the communication speed obtained in the actual communication environment does not satisfy the determined UE-AMBR value due to the influence of the load.

  Moreover, when the upper limit determination unit 403 receives, from the secondary eNB, the wireless quality information in the terminal device together with the UE-AMBR readjustment request via the wired communication unit 402, the UE-AMBR The value of AMBR may be readjusted. Here, the information on the radio quality relates to, for example, a path loss value or an interference signal strength for a radio signal transmitted or received (that is, uplink or downlink) between the terminal device and the secondary eNB. Can contain a value. Further, the wireless quality information may be information on a communication speed (bit rate) actually obtained between the secondary eNB and the terminal device. The value of the path loss is a value indicating how much power loss has occurred when the wireless signal passes through the transmission path, for example, obtained by the difference between the transmission power and the reception power of the wireless signal. Further, the value related to the intensity of the interference signal may be, for example, SINR (signal to interference and noise power ratio), CINR (carrier to interference and noise power ratio), or interference power.

  When receiving the radio quality information related to the secondary eNB, the upper limit determination unit 403 compares the radio quality information related to the master eNB with the UE-AMBR according to the comparison result. For example, the upper limit determination unit 403 performs UE-AMBR readjustment so that the eNB with better radio quality has a higher UE-AMBR value. Since the master eNB cannot directly know the radio quality in the secondary eNB of the uplink in particular, the UE-AMBR can be readjusted more appropriately by notifying the master eNB of this. It becomes. Also, regarding the downlink, when the secondary eNB periodically acquires information on the radio quality and notifies the master eNB, the master eNB updates the latest information as compared to acquiring the information by, for example, Measurement Report. It can be acquired more easily. Therefore, upper limit determination section 403 can perform UE-AMBR readjustment more appropriately based on the latest information.

  Moreover, the upper limit determination unit 403 may receive the information on the radio quality regarding the secondary eNB together with the above-described indicator regarding the load state. In this case, the upper limit determination unit 403, for example, performs readjustment of the UE-AMBR value so that the UE-AMBR value of the eNB having a low load and good radio quality is set to a larger value. It can be carried out. In addition, when the value of the UE-AMBR for one of the eNBs is changed, the upper limit determination unit 403 also adjusts the value of the UE-AMBR for the other eNB so that the total becomes a constant value. Readjust.

  Note that the above-described determination method is merely an example, and UE-AMBR readjustment may be performed in any manner. In some cases, the master eNB can ignore a request for readjustment of the UE-AMBR value from the secondary eNB. For example, when the communication speed obtained in the actual communication environment for both the master eNB and the secondary eNB does not satisfy the UE-AMBR value, the actual communication speed is the sum of the communication speeds corresponding to the terminal devices. It is considered that the upper limit is not reached. Therefore, in such a case, even if the master eNB receives a request from the secondary eNB, it may be considered that the UE-AMBR value is not readjusted.

  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, a readjustment determination unit 503, and a readjustment request unit 504. Further, the secondary eNB may include, for example, a request value determining unit 505, a load state specifying unit 506, and a radio quality specifying unit 507.

  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. Note that the radio communication unit 501 sets an upper limit value of the communication speed with the terminal device based on the UE-AMBR value notified from the master eNB via the wired communication unit 502, and performs communication below the upper limit value, for example. It communicates with the terminal device at speed.

  The wired communication unit 502 is a functional unit for performing wired communication, and establishes a connection between a network node such as an S-GW and the master eNB and performs wired communication. For example, the wired communication unit 502 receives UE-AMBR, which is the upper limit value of the communication speed between the secondary eNB and the terminal device, transmitted from the master eNB. The received UE-AMBR value is input to the radio communication unit 501 and the readjustment determination unit 503, for example. Also, the wired communication unit 502 transfers data received from the terminal device by the wireless communication unit 501 to the S-GW, or transmits data transferred from the S-GW to the terminal device via the wireless communication unit 501. To do. For example, when communication data between the secondary eNB and the terminal device is transmitted / received via the master eNB, data is transmitted / received to / from the master eNB, and data is transmitted / received to / from the S-GW. It can be configured not to. 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 readjustment determination unit 503 holds the UE-AMBR value notified from the master eNB and determines whether the value should be readjusted. Whether the readjustment determination unit 503 should readjust the UE-AMBR value based on the UE-AMBR value notified from the master eNB and the communication speed obtained by the wireless communication unit 501, for example. Determine. For example, the readjustment determination unit 503 performs readjustment of the UE-AMBR value when the communication speed obtained for a certain terminal device in the wireless communication unit 501 does not satisfy the UE-AMBR value for the terminal device. Determine that should be done. Note that the readjustment determination unit 503 determines whether readjustment should be performed according to, for example, the state of the load specified by the load state specifying unit 506, which will be described later, instead of the actually obtained communication speed. Good. For example, the readjustment determination unit 503 determines the load state determination unit 506 as the load state based on the number of terminal devices connected to the secondary eNB, the number of terminal devices whose queue length is not 0, and the like. The communication speed expected to be obtained in the future can be estimated. Then, the readjustment determination unit 503 compares the estimated communication speed with the value of the UE-AMBR. If the estimated communication speed is lower, the readjustment of the UE-AMBR value should be performed. Can be determined. Further, even when the communication speed actually obtained between the secondary eNB and the terminal or the estimated value thereof does not satisfy the UE-AMBR value, the readjustment determining unit 503 has a difference between the values less than the predetermined value. , It may not be determined that the UE-AMBR should be readjusted. This is because when the difference is small, it is considered that the communication speed of the target terminal device is not suppressed “excessively”.

  When the readjustment determination unit 503 determines that readjustment of the UE-AMBR value should be performed, the readjustment request unit 504 generates a signal for requesting readjustment, and via the wired communication unit 502, The request signal is transmitted to the master eNB. At this time, the readjustment request unit 504 may also transmit the request value of the UE-AMBR value determined by the request value determination unit 505.

  The request value determination unit 505 determines, for example, a value equal to or lower than the communication speed value actually obtained by the wireless communication unit 501 as the request value. In addition, the request value determination unit 505, for example, an index indicating the load state of the secondary eNB specified by the load state specification unit 506 and the radio quality between the secondary eNB specified by the radio quality specification unit 507 and the terminal device. The required value may be determined based on the information. Note that the index indicating the load state and the wireless quality information are, for example, the information described with respect to the upper limit determination unit 403. For example, the required value determination unit 505 can decrease the required value as the load increases, and increase the required value as the load decreases. Further, the required value determination unit 505 can increase the required value as the radio quality is better, and can decrease the required value as the radio quality is not better. Further, the required value determination unit 505 determines the required value by using the load state index and the wireless quality information in combination, such as increasing the required value as the load is smaller and the wireless quality is better. Also good.

  When the readjustment determination unit 503 determines that readjustment of the UE-AMBR value should be performed, the readjustment request unit 504 includes the secondary eNB specified by the load state specifying unit 506 together with a signal requesting readjustment. You may transmit the parameter | index which shows the state of the load in. The load state identification unit 506 identifies, for example, at least one of the usage status of the physical resource block (PRB) in the secondary eNB or information regarding the terminal device connected to the secondary eNB. Specifically, for example, the load state identification unit 506 grasps the number of PRBs being used and divides the number by the number of all PRBs to calculate a ratio. Further, the load state identification unit 506 may classify the PRBs used into those used in the GBR bearer and those used in the Non-GBR bearer, and calculate the ratio thereof. . Further, the load state identification unit 506 may obtain, for example, the number of unused PRBs by counting, and further divide the number of unused PRBs by the number of all PRBs, The ratio may be calculated. Moreover, the load state specific | specification part 506 may count and acquire the number of the terminal devices from which the queue length is not 0 among the terminal devices connected to secondary eNB, and also the predetermined period of the number, for example. You may calculate the average value in. Also, the load state identification unit 506 may count and acquire the number of terminal devices that have established a radio link (in an RRC_Connected state), for example.

  When the readjustment determination unit 503 determines that the readjustment of the UE-AMBR value should be performed, the readjustment request unit 504 includes the secondary eNB specified by the radio quality specifying unit 507 together with the signal requesting readjustment. Wireless quality information between the terminal device and the terminal device may be transmitted. The radio quality identification unit 507, for example, includes a path loss value and a value related to the strength of the interference signal for a radio signal transmitted or received (that is, uplink or downlink) between the terminal device and the secondary eNB. Specify at least one. The radio quality identification unit 507 can identify the path loss value, for example, by calculating the difference between the transmission power and the reception power of the radio signal. Further, the radio quality specifying unit 507 acquires a value related to the intensity of the interference signal by specifying SINR (signal to interference and noise power ratio), CINR (carrier to interference and noise power ratio), or interference power, for example. can do. Note that the radio quality identification unit 507 may identify the communication speed (bit rate) actually obtained between the secondary eNB and the terminal device. For example, the radio quality identification unit 507 can acquire information on the actual communication speed between the terminal device and the secondary eNB by monitoring the radio communication unit 501.

  The request value determining unit 505, the load state specifying unit 506, and the radio quality specifying unit 507, for example, monitor the radio communication unit 501, respectively, to request a UE-AMBR request value, an index indicating a load state, and radio quality Determine or identify information. Note that the secondary eNB does not need to have all of these functional units, and may or may not have some or all of them.

(Process flow)
Then, the process performed between the above master eNBs and secondary eNBs is demonstrated using FIG. First, for a certain terminal device, the master eNB initially transmits a secondary eNB addition request (SeNB Addition Request) to another eNB based on, for example, information on the radio quality observed by the terminal device. . At this time, for example, the master eNB determines and notifies the UE-AMBR value of the secondary eNB to be added based on the radio quality notified by the Measurement Report that triggers the addition request of the secondary eNB (S601). The subsequent processing is omitted here, but here, it is assumed that the master eNB and the secondary eNB have both transitioned to the state of Dual Connectivity that communicates with one terminal device by completing this processing. .

  Thereafter, the UE-AMBR should be readjusted because, for example, the communication speed actually obtained between the secondary eNB and the terminal device is less than the notified UE-AMBR value. It is determined that there is (S602). Then, in response to this determination, the secondary eNB transmits a UE-AMBR readjustment request to the master eNB (S603). At this time, in addition to this request, the secondary eNB may transmit to the master eNB at least one of a UE-AMBR request value, an index indicating a load state, radio quality information, and communication speed information. Good.

  When receiving the readjustment request, the master eNB performs readjustment of the UE-AMBR value (S604). For example, when it can be determined that the readjustment request is received when the communication speed actually obtained in the secondary eNB does not satisfy the previously notified UE-AMBR value, the master eNB determines the UE of the secondary eNB. -Decrease the value of AMBR. At this time, the master eNB also adjusts the UE-AMBR value of the master eNB, and re-adjusts the sum of the master eNB UE-AMBR value and the secondary eNB UE-AMBR value to a constant value. I do.

  In addition, when the master eNB receives the request value together, for example, the value of the UE-AMBR of the secondary eNB becomes the request value, or between the request value and the current UE-AMBR value. You may readjust UE-AMBR so that it may become a value. In addition, when the master eNB also receives an indicator indicating the load state, for example, the master eNB may readjust the UE-AMBR so that the value of the UE-AMBR decreases as the load increases. In addition, when the master eNB receives the radio quality information, the master eNB can also readjust the UE-AMBR so that the better the radio quality, the larger the UE-AMBR value. Furthermore, when the master eNB receives the indicator indicating the load state and the information on the radio quality, the UE-AMBR is retransmitted so that the UE-AMBR value increases as the load is lower and the radio quality is higher. Adjustments may be made. Also, when the master eNB receives information on the communication speed between the secondary eNB and the terminal device that is actually obtained, the master eNB determines the UE-AMBR value of the secondary eNB so as not to exceed the communication speed. can do. Further, the master eNB selects one candidate closest to the actual communication speed value from among a plurality of UE-AMBR candidates, and determines the value of the one candidate as the UE-AMBR value of the secondary eNB. May be.

  When the master eNB receives a plurality of UE-AMBR request values, load state indicators, radio quality information, and communication speed information, a part of the received information is transferred to the UE. -It may be used selectively for readjustment of AMBR. Moreover, even if the master eNB receives these information, it is not necessary to use these information for readjustment of UE-AMBR. Furthermore, the master eNB may ignore the readjustment request itself.

  When the master eNB completes the UE-AMBR readjustment, the master eNB notifies the secondary eNB of the value of the secondary eNB UE-AMBR determined by the readjustment (S605). Thereafter, the master eNB and the secondary eNB limit the communication speed of communication with the terminal device based on the UE-AMBR after readjustment.

  Thereby, the communication speed of communication between the master eNB and the secondary eNB and the terminal device can be suppressed to a certain value or less, and the communication speed of the terminal device is excessively suppressed, for example, according to the state of the secondary eNB. It becomes possible to prevent this. That is, it is possible to appropriately control the communication speed between a plurality of base station apparatuses and terminal apparatuses.

Claims (13)

A terminal device is connected to a base station device and another base station device, and the total communication speed between the base station device and the other base station device is limited to a certain value or less. In the radio communication system, the base station apparatus,
Determination means for determining whether the upper limit value of the communication speed between the base station apparatus and the terminal apparatus notified from the other base station apparatus should be readjusted;
When the determination means determines that the upper limit value should be readjusted, request means for requesting the other base station apparatus to readjust the upper limit value;
A base station apparatus comprising: Further comprising a determining means for determining a request value for the upper limit value in the base station device;
The request means transmits the request value to the other base station device when requesting readjustment.
The base station apparatus according to claim 1. A specifying means for specifying an index indicating a load state in the base station device;
The request means transmits the indicator to the other base station device when requesting readjustment.
The base station apparatus according to claim 1, wherein the base station apparatus is a base station apparatus. The index is used for a communication link in which the usage rate of the physical resource block, the ratio of the physical resource block used for the communication link for which the communication speed is guaranteed, and the communication link for which the communication speed is not guaranteed in the base station apparatus. The ratio of physical resource blocks, the number or ratio of free physical resource blocks, the number of terminal devices whose queue length is not 0, the average value of the number of terminal devices over a predetermined period, and the number of terminal devices that have established radio links Including at least one of the numbers,
The base station apparatus according to claim 3. It further has an acquisition means for acquiring radio quality information about a radio signal transmitted or received between the base station apparatus and the terminal apparatus,
The request means transmits the radio quality information to the other base station device when requesting readjustment.
The base station apparatus according to claim 1, wherein the base station apparatus is a base station apparatus. The radio quality includes at least one of a path loss value and an interference signal strength value for the radio signal.
The base station apparatus according to claim 5. The request means, when requesting readjustment, transmits information on the communication speed actually achieved in the base station apparatus to the other base station apparatus.
The base station apparatus according to claim 1, wherein the base station apparatus is a base station apparatus. A terminal device is connected to a base station device and another base station device, and the total communication speed between the base station device and the other base station device is limited to a certain value or less. In the radio communication system, the base station apparatus,
Notifying means for notifying the other base station device of the upper limit value of the communication speed between the other base station device and the terminal device;
Receiving means for receiving a request for readjustment of the upper limit value from the other base station device;
Readjustment means for readjusting the upper limit in response to receiving the request;
Have
The notifying means notifies the readjusted upper limit value to the other base station device;
A base station apparatus. The sum of the communication speeds is a sum of communication speeds related to communication links for which communication speed is not guaranteed.
The base station apparatus according to claim 1, wherein the base station apparatus is a base station apparatus. A terminal device is connected to a base station device and another base station device, and the total communication speed between the base station device and the other base station device is limited to a certain value or less. A control method for the base station apparatus in a wireless communication system, comprising:
A determination step of determining whether the upper limit value of the communication speed between the base station apparatus and the terminal apparatus notified from the other base station apparatus is to be readjusted;
When the requesting unit determines that the upper limit value should be readjusted in the determination step, the requesting step requests the other base station device to readjust the upper limit value;
A control method characterized by comprising: A terminal device is connected to a base station device and another base station device, and the total communication speed between the base station device and the other base station device is limited to a certain value or less. A control method for the base station apparatus in a wireless communication system, comprising:
A notification step of notifying the other base station device of an upper limit value of a communication speed between the other base station device and the terminal device;
A receiving step for receiving a request for readjustment of the upper limit value from the other base station device; and
A readjustment step in which the readjustment means readjusts the upper limit value in response to receiving the request;
The notifying means notifying the other base station apparatus of the readjusted upper limit value;
A control method characterized by comprising: A terminal device is connected to a base station device and another base station device, and the total communication speed between the base station device and the other base station device is limited to a certain value or less. In a computer provided in the base station apparatus in a wireless communication system,
A determination step of determining whether the upper limit value of the communication speed between the base station apparatus and the terminal apparatus notified from the other base station apparatus should be readjusted;
If it is determined in the determination step that the upper limit value should be readjusted, a request step for requesting the other base station device to readjust the upper limit value;
A program for running A terminal device is connected to a base station device and another base station device, and the total communication speed between the base station device and the other base station device is limited to a certain value or less. In a computer provided in the base station apparatus in a wireless communication system,
A notification step of notifying the other base station device of an upper limit value of a communication speed between the other base station device and the terminal device;
A receiving step of receiving a request for readjustment of the upper limit value from the other base station device;
A readjustment step of readjusting the upper limit in response to receiving the request;
Notifying the other base station apparatus of the readjusted upper limit value;
A program for running

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