JP5621924B2 - base station - Google Patents

Description

This case relates to a base station for performing radio communication with a radio terminal.

  Currently, mobile communication systems such as mobile phone systems are widely used, and the next generation mobile communication technology is continuously discussed in order to further increase the speed and capacity of wireless communication.

  For example, a standard called LTE (Long Term Evolution) is proposed in 3GPP (3rd Generation Partnership Project) of the international standardization organization. In addition, a standard called LTE-A (LTE-Advanced) that extends LTE has been proposed. In standardization of LTE-A, studies for providing higher-speed data communication have been made, but a wide frequency band is required to realize this. On the other hand, since frequencies are allocated avoiding existing allocated frequency bands, it is difficult to allocate a wide frequency continuously.

  As a countermeasure, a carrier aggregation (CA) technique that uses a plurality of frequency bands for downlink communication and performs processing on a baseband of a UE (User Equipment) has been studied. In the CA technology, each frequency band is called a component carrier (CC).

Conventionally, in a communication system that performs cooperative communication, a communication system that efficiently performs adaptive control has been proposed mainly for precoding processing (see, for example, Patent Document 1).
Conventionally, there has been proposed a resource control system that enables improvement of QoS considering the entire system and effective use of resources by coordinating resource control between the own cell and neighboring cells (for example, Patent Documents). 2).

JP 2011-004161 A JP 2003-199144 A

However, the information society will continue to advance, and further increases in data communication speed and capacity are desired.
The present case has been made in view of such points, and an object thereof is to provide a base station capable of increasing the speed and capacity of data communication.

In order to solve the above-described problem, a transmission unit that transmits data to a wireless terminal using a plurality of frequency bands and a transmission unit that transmits data to the wireless terminal in another base station are transmitted. A transfer unit that transfers a part of the data to the other base station, and the transmission unit is configured to transmit the plurality of frequency bands based on both or one of a retention amount and a retention time of data to be transmitted to the wireless terminal. Is provided, and the transfer unit is provided with a base station that starts data transfer based on both or one of the staying amount and the staying time.

According to the disclosed apparatus and method, it is possible to increase the speed and capacity of data communication.
These and other objects, features and advantages of the present invention will become apparent from the following description taken in conjunction with the accompanying drawings which illustrate preferred embodiments by way of example of the present invention.

It is a figure explaining the base station which concerns on 1st Embodiment. It is the 1 of the figure explaining CA. It is the 2 of the figure explaining CA. It is a figure explaining radio | wireless resource allocation of the radio | wireless terminal of FIG. It is the figure which showed the example of the radio | wireless communications system which concerns on 2nd Embodiment. It is a figure explaining operation | movement of the radio | wireless communications system of FIG. It is the flowchart which showed operation | movement of eNB. It is a sequence diagram of a radio | wireless communications system. It is a sequence diagram of a radio | wireless communications system. It is a sequence diagram of a radio | wireless communications system. It is a sequence diagram of a radio | wireless communications system. It is a sequence diagram of a radio | wireless communications system. It is the figure which showed the hardware structural example of eNB. It is the figure which showed the functional block of eNB. It is the sequence diagram which showed CA start process. It is the sequence diagram which showed CA start process. It is a figure explaining a transmission buffer management table. It is a figure explaining selection of a monitoring frequency band. It is the sequence diagram which showed the radio | wireless resource allocation request | requirement process of Scell. It is a figure explaining determination of the priority in another station. It is the sequence figure which showed the processing delay measurement processing of data transfer. FIG. 10 is another sequence diagram showing a process delay measurement process for data transfer. It is the 1 of the figure explaining CA process. It is the 2 of the figure explaining CA process. It is the figure which showed the data format example of the data transferred to eNB of another station. It is the figure which showed the flow of the data in a downlink layer.

Hereinafter, embodiments will be described in detail with reference to the drawings.
[First Embodiment]
FIG. 1 is a diagram for explaining a base station according to the first embodiment. In FIG. 1, base stations 1 and 2 and a wireless terminal 3 are shown. The base station 2 is, for example, an adjacent base station of the base station 1. The wireless terminal 3 is, for example, a mobile phone. As shown in FIG. 1, the base station 1 includes a transmission unit 1a and a transfer unit 1b.

  The transmitter 1a transmits data to the wireless terminal 3 by CA. The transfer unit 1 b transfers a part of the data transmitted by the transmission unit 1 a to the wireless terminal 3 to the base station 2 so that the data transmission to the wireless terminal 3 is performed in the other base station 2.

  The base station 2 has a receiving unit 2a and a transmitting unit 2b. The receiving unit 2 a receives data transferred from the transfer unit 1 b of the base station 1. That is, the receiving unit 2 a receives from the base station 1 part of data that the base station 1 transmits to the wireless terminal 3 by CA. The transmission unit 2b transmits the data received by the reception unit 2a to the wireless terminal 3.

  The CA will be described. FIG. 2 is a first diagram illustrating CA. 2A and 2B show band examples of a CA radio communication system. 2A shows the frequency band on the radio frequency, and FIG. 2B shows the frequency band on the baseband of the radio terminal.

  In a wireless communication system that does not perform CA, a base station and a wireless terminal perform wireless communication in a single frequency band. In contrast, in a wireless communication system that performs CA, a base station and a wireless terminal perform wireless communication in a plurality of frequency bands.

  For example, the base station and the wireless terminal perform wireless communication in a plurality of frequency bands 11, 13, and 15 as shown in FIG. Note that the frequency bands 12 and 14 indicate, for example, the frequency bands of the wireless communication systems of other companies.

  As shown in FIG. 2B, the wireless terminal performs signal processing by integrating the plurality of frequency bands 11a, 13a, and 15a on the baseband. That is, the wireless terminal performs signal processing by performing data communication with the base station in a frequency band wider than a single frequency band.

  FIG. 3 is a second diagram illustrating CA. FIG. 3 shows a base station 21 and a wireless terminal 22. As shown in FIG. 3, the base station 21 forms a cell 23 in the frequency band f1 and a cell 24 in the frequency band f2.

  When the radio terminal 22 connects to the base station 21, the frequency band assigned to the radio terminal 22 is referred to as a primary frequency band. Moreover, the cell of a primary frequency band is called a primary cell (Pcell: Primary cell).

  For example, assume that when the wireless terminal 22 is connected to the base station 21, the frequency band f1 is assigned to the wireless terminal 22. In this case, the cell 23 becomes the Pcell of the wireless terminal 22. When the wireless terminal 22 is initially connected to the base station 21, the wireless terminal 22 transmits and receives data using the Pcell (cell 23).

  When the base station 21 has the CA function, the base station 21 inquires the radio terminal 22 about which frequency band it can communicate with. In response to the inquiry from the base station 21, the wireless terminal 22 returns a communicable frequency band.

  The base station 21 selects a frequency band that can be communicated with the wireless terminal 22 among frequency bands other than the primary frequency band provided by the base station 21. This selected frequency band is called a secondary frequency band. Moreover, the cell of a secondary frequency band is called a secondary cell (Scell: Secondly cell). The base station 21 instructs the wireless terminal 22 to perform communication using the selected Scell. This instruction is given by Pcell.

  For example, it is assumed that the base station 21 receives frequency bands f1 and f2 from the wireless terminal 22 as communicable frequency bands. In this case, the base station 21 selects the cell 24 as Scell. Then, the base station 21 instructs the wireless terminal 22 to perform communication also in the Scell (cell 24). Thereby, the base station 21 and the radio | wireless terminal 22 can perform the radio | wireless communication of CA by several frequency band f1, f2.

  Downlink scheduling is performed by Pcell PDCCH (Physical Downlink Control Channel). Further, addition, change, and release of Scell are performed by Pcell PDCCH. In addition, downlink data transmission is performed by PDSCH (Physical Downlink Shared Channel) of Pcell and Scell.

  For example, an arrow A1 shown in FIG. 3 indicates PDCCH. An arrow A2 indicates the PDSCH of Pcell. Arrow A3 indicates PDSCH of Scell. The PDCCH indicated by the arrow A1 indicates that the scheduling of the Pcell PDSCH indicated by the arrow A2 and the Scell PDSCH indicated by the arrow A3 is transmitted.

  Thus, in CA, the base station 21 and the wireless terminal 22 perform wireless communication in a plurality of frequency bands f1 and f2. Thereby, the base station 21 and the radio | wireless terminal 22 can perform radio | wireless communication in a frequency band wider than a single frequency band, and can achieve high-speed and large capacity | capacitance of data communication.

  Returning to the description of FIG. As described above, the transmission unit 1a of the base station 1 in FIG. 1 transmits data to the wireless terminal 3 by CA. The transfer unit 1b bases a part of the data transmitted by the transmission unit 1a so that a part of the data transmitted to the wireless terminal 3 of the transmission unit 1a is also transmitted to the wireless terminal 3 in the other base stations 2. Transfer to station 2. The receiving unit 2a of the base station 2 receives the data transferred by the transfer unit 1b of the base station 1, and the transmitting unit 2b transmits the data received by the receiving unit 2a to the wireless terminal 3.

FIG. 4 is a diagram illustrating radio resource allocation of the radio terminal in FIG. The horizontal axis shown in FIG. 4 indicates time, and the vertical axis indicates frequency.
Assume that the base station 1 shown in FIG. 1 can perform wireless communication in frequency bands f1 and f2, for example, as shown in FIG. Further, it is assumed that the base station 2 can perform wireless communication in the frequency bands f3 and f4. Further, it is assumed that the wireless terminal 3 can perform wireless communication in the frequency bands f1 to f3. 4 corresponds to the wireless terminal 3 in FIG. The UE 2 corresponds to a wireless terminal belonging to the base station 2 that is not illustrated in FIG.

  The transmission unit 1a of the base station 1 transmits data to the radio terminal 3 in a plurality of frequency bands by CA. For example, as shown in FIG. 4, radio resources in frequency bands f1 and f2 are allocated to the radio terminal 3 (UE1). In FIG. 4, the frequency band f1 is Pcell and the frequency band f2 is Scell.

  The transfer unit 1b of the base station 1 transfers a part of the data to the base station 2 so that the data to be transmitted to the radio terminal 3 of the transmission unit 1a is transmitted to the radio terminal 3 also in the other base station 2. . The receiving unit 2a of the base station 2 receives the data transferred from the transferring unit 1b of the base station 1, and the transmitting unit 2b converts the data received by the receiving unit 2a into the frequency of the CA of the transmitting unit 1a of the base station 1. It transmits to the wireless terminal 3 in a frequency band different from the band.

  For example, the data within the dotted frame D1 shown in FIG. 4 indicates data addressed to the wireless terminal 3 transferred from the base station 1 to the base station 2. The data transferred from the base station 1 to the base station 2 is assigned to the radio resource in the frequency band f3 of the base station 2 in FIG.

  That is, the base station 1 adds the frequency band f3 of the other base station 2 as a secondary frequency band to the frequency bands f1 and f2 of its own CA, and data transmission from the other base station 2 to the wireless terminal 3 is also performed. Like that. If base station 2 has radio resources in a plurality of frequency bands, base station 2 may assign the data transferred from base station 1 to the plurality of frequency bands.

  As described above, the transfer unit 1b of the base station 1 transfers a part of the data transmitted by the transmission unit 1a to the other base station so that the data transmission to the wireless terminal 3 is performed in the other base station 2. 2 was transferred. The receiving unit 2a of the base station 2 receives the data transferred by the transfer unit 1b of the base station 1, and transmits the data to the wireless terminal 3 by the transmitting unit 2b. Thereby, the base station 1 adds the frequency band of the other base station 2 to its own CA and performs data transmission to the wireless terminal 3, so that it is possible to increase the speed and capacity of data communication.

[Second Embodiment]
Next, a second embodiment will be described in detail with reference to the drawings.
FIG. 5 is a diagram illustrating an example of a wireless communication system according to the second embodiment. As illustrated in FIG. 5, the wireless communication system includes eNBs 31 and 32, MME (Mobility Management Entity) 33, and UEs 34 and 35. As illustrated in FIG. 5, the eNBs 31 and 32 are connected to each other. For example, there may be an S-GW (Serving-Gateway) between the eNBs 31 and 32. The eNBs 31 and 32 are connected via the MME 33.

FIG. 6 is a diagram for explaining the operation of the wireless communication system of FIG. In FIG. 6, the same components as those in FIG.
The eNBs 31 and 32 are connected via an X2 interface. Further, eNB 31 and MME 33 is connected with the S1 interface. Also, the eNB 32 and the MME 33 are connected via an S1 interface.

  The eNB 31 can perform radio communication with the UEs 34 and 35 using the frequency bands f1 and f2, for example. A cell 41 indicates a cell in the frequency band f1, and a cell 42 indicates a cell in the frequency band f2.

  The eNB 32 can perform radio communication with the UEs 34 and 35 by using the frequency bands f3 and f4, for example. A cell 43 indicates a cell in the frequency band f3, and a cell 44 indicates a cell in the frequency band f4.

  For example, the UE 34 can perform radio communication in the frequency bands f1 to f3. In addition, in FIG. 6, since UE34 belongs to the cells 41-43 of the frequency bands f1-f3, it can perform radio | wireless communication with both eNB31 and eNB32.

  For example, the UE 35 can perform radio communication in the frequency bands f1, f3, and f4. In FIG. 6, since the UE 35 belongs to the cells 43 and 44 in the frequency bands f3 and f4, the UE 35 can perform radio communication with the eNB 32.

  The eNB 31 can perform data transmission to the UE 34 by CA. For example, when the retention amount and the retention time of data to be transmitted to the UE 34 exceed a predetermined threshold, the eNB 31 transmits data to the UE 34 by the Pcell (for example, the cell 41) and the Scell (for example, the cell 42) by the CA. Do. In addition, if the UE 34 can wirelessly communicate with another eNB 32, the eNB 31 transfers a part of data to be transmitted to the UE 34 to the eNB 32.

  That is, the eNB 31 adds the cell 43 of the eNB 32 as a Scell to its own CA, and performs data transmission to the UE 34. That is, UE34 receives data from two eNBs, eNB31 and eNB32.

  FIG. 7 is a flowchart showing the operation of the eNB. FIG. 7 shows a flowchart of the eNB 31 of FIG. In FIG. 7, the UE 34 is assumed to be connected to the eNB 31 by setting the cell 41 of the eNB 31 to Pcell.

  [Step S1] The eNB 31 determines whether or not the retention amount and the retention time of data to be transmitted to the UE 34 exceed a predetermined threshold value. If the retention amount and the retention time of the data to be transmitted to the UE 34 exceed the predetermined threshold, the eNB 31 proceeds to step S2. The eNB 31 ends the process when the retention amount and the retention time of the data transmitted to the UE 34 do not exceed the predetermined threshold.

  [Step S2] The eNB 31 instructs the UE 34 to monitor a frequency band different from the frequency band f1 of the Pcell (cell 41). That is, the eNB 31 instructs the UE 34 to monitor a frequency band different from the frequency band f1 and capable of performing wireless communication with itself.

  [Step S3] The eNB 31 determines whether or not the UE 34 has received a detection notification of its own other cell (another frequency band different from the Pcell) from the UE 34. For example, the eNB 31 determines whether a detection notification of the cell 42 (frequency band f2) has been received from the UE 34. When the eNB 31 receives a notification of detection of its own other cell from the UE 34, the eNB 31 proceeds to step S4. If the eNB 31 does not receive the detection notification of its own other cell from the UE 34, the eNB 31 proceeds to step S5.

  [Step S4] The eNB 31 performs CA in its own eNB. For example, when receiving the detection result of the cell 42 from the UE 34 in step S3, the eNB 31 sets the cell 42 as a Scell and performs CA.

  [Step S5] The eNB 31 determines whether a cell detection notification in the other eNB 32 is received from the UE 34. For example, the eNB 31 determines whether the detection notification of the cells 43 and 44 (frequency bands f3 and f4) is received from the UE 34. When the eNB 31 receives a cell detection notification in the other eNB 32 from the UE 34, the eNB 31 proceeds to step S7. When the eNB 31 does not receive the cell detection notification in the other eNB 32 from the UE 34, the eNB 31 proceeds to step S6. In the example of FIG. 6, the eNB 31 receives the detection notification of the cell 43 from the UE 34.

[Step S6] The eNB 31 instructs the UE 34 to stop monitoring in a different frequency band (a frequency band other than the Pcell frequency band).
[Step S7] The eNB 31 adds a cell of another eNB 32 as a Scell. For example, the eNB 31 adds the cell 43 of the other eNB 32 to the Scell. eNB31 transfers a part of data transmitted to UE34 to eNB32, and eNB32 transmits the data transferred from eNB31 to UE34 in Scell (cell 43).

[Step S8] The eNB 31 performs Scell release, change processing, and Pcell change processing.
For example, when the eNB 31 determines that the congestion of data transmitted to the UE 34 has been resolved by the CA, the eNB 31 releases the Scell.

  In addition, when there is a Scell change or release process request from the eNB 32, the eNB 31 performs the Scell change or release process of the eNB 32. For example, when a UE having a higher data transmission priority than the UE 34 starts communication, the eNB 32 notifies the eNB 31 that the Scell of the UE 34 is changed or the Scell is released.

  Moreover, eNB31 changes Pcell to the cell of a frequency band with good communication quality. For example, when the UE 34 moves, the frequency band with good communication quality changes. In this case, the eNB 31 sets the cell in the frequency band with the best communication quality to Pcell.

In addition, eNB31 performs operation | movement of the flowchart shown in FIG. 7 with respect to all UE which belongs to own Pcell.
Further, the eNB 31 repeatedly performs the operation of the flowchart illustrated in FIG. Therefore, for example, if the retention amount and the retention time of the data transmitted to the UE 34 exceed the predetermined threshold after the CA is performed in step S4 of FIG. 7, the eNB 31 determines the Scell of the other eNB 32 by step S7. Will be added.

  In addition, since the eNB 31 repeatedly performs the operation of the flowchart illustrated in FIG. 7, even if a cell of another eNB 32 is added as a Scell, if the retention amount and the retention time of data transmitted to the UE 34 exceed a predetermined threshold, Other cells of other eNBs 32 may be added as Scells.

  In addition, the determination to start CA of the eNB 31 (the process of step S1) may be determined by one of the data retention amount and the retention time. For example, the eNB 31 may proceed to the process of step S2 if one of the retention amount and the retention time of data transmitted to the UE 34 exceeds a predetermined threshold. The same applies to the retention amount and residence time appearing below.

8 to 12 are sequence diagrams of the wireless communication system. 8 to 12 show sequences of the eNBs 31 and 32 and the UE 34 shown in FIG.
[Step S11] The eNB 31 and the UE 34 establish an RRC connection by an RRC (Radio Resource Control) connection sequence.

  [Step S12] The eNB 31 establishes a Pcell. For example, if the communication quality of the cell 41 is good among the cells 41 and 42 that communicate with the UE 34, the eNB 31 sets the cell 41 as Pcell.

[Step S13] The eNB 31 and the UE 34 establish a bearer.
[Step S14] The eNB 31 detects whether the retention amount and the retention time of the buffer that temporarily stores data to be transmitted to the UE 34 have exceeded a predetermined threshold. That is, the eNB 31 detects whether the retention amount and the retention time of data to be transmitted to the UE 34 exceed a predetermined threshold. Here, it is assumed that the eNB 31 detects that the retention amount and the retention time of data to be transmitted to the UE 34 exceed a predetermined threshold.

  [Step S15] In order to establish a call with the UE 34, the eNB 31 requests the UE 34 to reset the RRC connection. At this time, the eNB 31 instructs the UE 34 to monitor a frequency band in which communication is possible in a frequency band other than Pcell.

[Step S16] The UE 34 returns a response to the RRC connection reconfiguration request in Step S15 (completion of reconfiguration of the RRC connection) to the eNB 31.
[Step S17] The UE 34 returns the monitoring measurement result to the eNB 31. For example, the UE 34 returns the frequency band f2 (or Cell-ID (IDentifier) of the cell 42) and the frequency band f3 (or Cell-ID of the cell 43) to the eNB 31.

A dotted frame D11 illustrated in FIG. 8 indicates processing when the monitoring measurement result measured by the UE 34 is the frequency band of the own station (eNB 31).
[Step S18] From the monitoring result from the UE 34, the eNB 31 detects another frequency band of the own station (a frequency band different from Pcell). For example, the eNB 31 receives the frequency band f2 from the UE 34.

[Step S19] In order to establish a call with the UE 34, the eNB 31 requests the UE 34 to reset the RRC connection.
[Step S20] The UE 34 returns a response to the RRC connection reconfiguration request in Step S19 to the eNB 31.

  [Step S21] The eNB 31 adds its own cell as a Scell. For example, when the eNB 31 receives the frequency band f2 as another frequency band of its own station in step S18, the eNB 31 adds the cell 42 as a Scell. The eNB 31 notifies the added Scell to the UE 34. For example, the eNB 31 notifies the added Scell by Cell-ID.

A dotted line frame D12 illustrated in FIG. 9 illustrates processing when the monitoring measurement result measured by the UE 34 is the frequency band of the other station (eNB 32).
[Step S22] The eNB 31 detects the other frequency band of the other station (frequency band different from Pcell) from the monitoring result from the UE. For example, the eNB 31 receives the frequency band f3 (or its Cell-ID) from the UE 34.

  [Step S23] The eNB 31 makes a radio resource allocation request to the eNB 32. For example, in order to add the cell 43 in the frequency band f3 of the eNB 32 to the Scell, the eNB 31 makes an allocation request for radio resources in the frequency band f3.

  [Step S24] The eNB 32 determines whether radio resources can be allocated. For example, the eNB 31 determines whether or not radio resources in the frequency band f3 can be allocated to the UE 34.

[Step S25] The eNB 32 returns a result of whether or not radio resources can be allocated to the eNB 31.
[Step S26] The eNB 31 receives a result indicating that radio resources can be allocated. When the eNB 31 receives the result of the radio resource assignment failure and has added the Scell of its own station, the eNB 31 performs data communication with the UE 34 between the Pcell and the own Scell. In addition, when the eNB 31 receives the result of the radio resource allocation failure and does not add its own Scell, the eNB 31 performs data communication with the UE 34 using the Pcell.

  [Step S27] The eNB 31 makes a processing delay measurement request to the eNB 32. When eNB31 adds the cell of eNB32 of another station as Scell and transmits data to UE34, a part of data transmitted to UE34 is transferred to eNB32. This data transfer causes a time difference between the time when the eNB 31 transmits data to the UE 34 and the time when the eNB 32 transmits data to the UE 34. Therefore, the eNB 31 measures the data transfer time to the eNB 32 in order to perform scheduling in consideration of the time for data transfer to the eNB 32.

[Step S28] The eNB 32 receives the processing delay measurement request from the eNB 31, and gives the message the reception time of the processing delay measurement request.
[Step S29] The eNB 32 transmits a message with the reception time to the eNB 31. Note that the eNB 31 measures the data transfer time based on the time when the processing delay measurement request is made and the reception time given to the message.

[Step S30] In order to establish a call with the UE 34, the eNB 31 requests the UE 34 to reset the RRC connection.
[Step S31] The UE 34 returns a response to the RRC connection reconfiguration request in Step S30 to the eNB 31.

  [Step S32] The eNB 31 adds a cell of another station as a Scell. For example, the eNB 31 adds the cell 43 in the frequency band f3 of the eNB 32 as a Scell. The eNB 31 notifies the added Scell to the UE 34. For example, the eNB 31 notifies the added Scell by Cell-ID.

[Step S33] The eNB 31 transfers a part of data to be transmitted to the UE 34 to the eNB 32.
[Step S34] The eNBs 31 and 32 transmit data (U-plane data) to the UE 34 by Scell. The eNB 31 transmits data to the UE 34 even in the Pcell.

A dotted line frame D13 illustrated in FIG. 10 indicates a process in the case where the retention amount and the retention time of the data to be transmitted to the UE 34 are equal to or less than a predetermined threshold value.
[Step S35] The eNB 31 detects whether the retention amount and the retention time of the buffer that temporarily stores data to be transmitted to the UE 34 are equal to or less than a predetermined threshold. That is, the eNB 31 detects whether the retention amount and the retention time of the data to be transmitted to the UE 34 are equal to or less than a predetermined threshold value. Here, it is assumed that the eNB 31 detects that the retention amount and the retention time of data to be transmitted to the UE 34 are equal to or less than a predetermined threshold.

[Step S36] In order to establish a call with the UE 34, the eNB 31 requests the UE 34 to reset the RRC connection.
[Step S37] The UE 34 returns a response to the RRC connection reconfiguration request in Step S36 to the eNB 31.

  [Step S38] The eNB 31 releases its own Scell. For example, the eNB 31 releases the cell 42. The eNB 31 notifies the UE 34 that the Scell of its own station has been released.

[Step S39] The eNB 31 requests the eNB 32 to release Scell radio resources.
That is, when the data congestion of the UE 34 is reduced, the eNB 31 releases the Scells of the own station and other stations. And eNB31 transmits the data of UE34 only by Pcell.

  [Step S40] In response to the radio resource release request from the eNB 31, the eNB 32 updates the radio resource allocation information. For example, the eNB 32 updates that the radio resource of the frequency band f3 allocated to the UE 34 has been released.

[Step S41] The eNB 32 transmits a radio resource release response to the eNB 31.
[Step S42] In order to establish a call with the UE 34, the eNB 31 requests the UE 34 to reset the RRC connection.

[Step S43] The UE 34 returns to the eNB 31 a response to the RRC connection reconfiguration request in Step S42.
[Step S44] The eNB 31 notifies the UE 34 that the Scell of another station cell has been released. For example, the eNB 31 notifies the UE 34 that the Scell cell 43 of the eNB 32 has been released.

A dotted frame D <b> 14 illustrated in FIG. 11 indicates a process for changing the Scell radio resource.
[Step S45] The eNB 32 detects a change in radio resources allocated to the UE 34. For example, since there is a UE having a higher priority than the UE 34, the eNB 32 detects a change in the radio resource when a part of the radio resource assigned to the UE 34 is assigned to the UE.

[Step S46] The eNB 32 transmits a radio resource change request to the eNB 31.
[Step S47] The eNB 31 changes the radio resource allocated to the UE 34.

[Step S48] The eNB 31 transmits a radio resource change response to the eNB 32.
[Step S49] The eNB 32 updates the radio resource allocation information of the UE. For example, the eNB 32 updates that the radio resource of the frequency band f3 allocated to the UE 34 has been reduced.

A dotted line frame D15 illustrated in FIG. 12 indicates a release process of Scell radio resources.
[Step S50] The eNB 32 detects release of radio resources allocated to the UE 34. For example, since there is a UE having a higher priority than the UE 34, the eNB 32 detects the release of the radio resource when the radio resource allocated to the UE 34 is allocated to the UE.

[Step S51] The eNB 32 transmits a radio resource release request to the eNB 31.
[Step S52] In order to establish a call with the UE 34, the eNB 31 requests the UE 34 to reset the RRC connection.

[Step S53] The UE 34 returns a response to the RRC connection reconfiguration request in Step S52 to the eNB 31.
[Step S54] The eNB 31 transmits a radio resource release response to the eNB 32.

  [Step S55] The eNB 32 changes the radio resource allocation information of the UE 34. For example, the eNB 32 updates that the radio resource of the frequency band f3 allocated to the UE 34 has been released.

  [Step S56] The eNB 31 notifies the UE 34 that the Scell of the other station has been released. For example, the eNB 31 notifies the UE 34 that the cell 43 of the eNB 32 has been released.

  In the above sequence, the eNBs 31 and 32 have described the case of exchanging data with the X2 interface based on the X2AP (X2 Application Protocol). However, based on the S1AP (S1 Application Protocol), Data may be exchanged. That is, the eNBs 31 and 32 may exchange data via the MME 33.

  FIG. 13 is a diagram illustrating a hardware configuration example of the eNB. As illustrated in FIG. 13, the eNB 31 includes a system-on-chip 51, a wireless module 52, and an optical module 53.

  The system-on-chip 51 includes a CPU (Central Processing Unit) 51a, memories 51b and 51d, and a DSP (Digital Signal Processing) 51c. The entire system-on-chip 51 is controlled by the CPU 51a. A memory 51b and a DSP 51c are connected to the CPU 51a via a bus.

  The memory 51b stores an OS (Operating System) program and application programs executed by the CPU 51a. The memory 51b stores various data necessary for processing by the CPU 51a.

  The memory 51d stores OS programs and application programs executed by the DSP 51c. The memory 51d stores various data necessary for processing by the DSP 51c. An FPGA (Field Programmable Gate Array) may be mounted instead of the DSP 51c.

  The radio module 52 performs radio communication with the UE. For example, the radio module 52 up-converts the frequency of the signal transmitted to the UE or down-converts the frequency of the signal received from the UE.

  The optical module 53 communicates with another eNB 32 by light. The optical module 53 communicates with the MME 33 by light. The eNB 32 has the same hardware as that shown in FIG.

  The functions of the transmission unit 1a and the transfer unit 1b in FIG. 1 are realized by, for example, the DSP 51c illustrated in FIG. The functions of the receiving unit 2a and the transmitting unit 2b in FIG. 1 are realized by, for example, the DSP 51c illustrated in FIG. The process of the flowchart of FIG. 7 is performed by the DSP 51c.

  FIG. 14 is a diagram illustrating functional blocks of the eNB. As illustrated in FIG. 14, the eNB 31 includes a transport unit 61, a call processing control unit 62, a BB (Base Band) processing unit 63, and a radio unit 64. The function of the transport unit 61 shown in FIG. 14 is realized by, for example, the optical module 53 shown in FIG. The functions of the call processing control unit 62 and the BB processing unit 63 are realized by, for example, the DSP 51c. The function of the wireless unit 64 is realized by the wireless module 52, for example.

  The transport unit 61 communicates with the eNB 32 or the MME 33 based on, for example, a protocol below the SCTP (Stream Control Transmission Protocol) layer. The call processing control unit 62 performs, for example, call processing of the UE 34. The BB processing unit 63 performs baseband processing of data communicated with the UE 34. The radio unit 64 performs radio communication with the UE 34. Note that the eNB 32 also has the same functional blocks as in FIG. 7 is performed by the call processing control unit 62 and the BB processing unit 63. The processing of steps S3 to S7 is performed by the call processing control unit 62.

Hereinafter, the sequence described with reference to FIGS. 8 to 12 will be described in detail. First, the CA start process will be described.
15 and 16 are sequence diagrams showing the CA start process. The sequence diagrams of FIGS. 15 and 16 correspond to, for example, the process of step S14 of FIG.

  [Step S61] The BB processing unit 63 of the eNB 31 calculates a retention amount and a retention time of a buffer that temporarily stores data to be transmitted to the UE 34. That is, the BB processing unit 63 calculates the retention amount and the retention time of the untransmitted data of the UE 34. The BB processing unit 63 stores the calculated staying amount and staying time in the buffer information management table. The buffer information management table is formed in, for example, the memory 51d shown in FIG.

[Step S62] The call processing control unit 62 reads the retention amount and residence time of the UE 34 stored in the buffer information management table.
[Step S63] The call processing control unit 62 receives the retention amount and residence time of the UE 34 read from the buffer information management table.

  [Step S64] The call processing control unit 62 stores and updates the received retention amount and residence time of the UE 34 in the transmission buffer management table. The transmission buffer management table is formed in, for example, the memory 51d shown in FIG.

  [Step S65] The call processing control unit 62 determines whether the staying amount and the staying time exceed the threshold. If the staying amount and the staying time exceed the predetermined threshold, the call processing control unit 62 proceeds to step S66. If the staying amount and staying time are equal to or less than the predetermined threshold, the call processing control unit 62 proceeds to step S62.

[Step S66] The call processing control unit 62 updates the priority of the UE 34 storing the staying amount and staying time in the transmission buffer management table.
FIG. 17 is a diagram for explaining the transmission buffer management table. As shown in FIG. 17, the transmission buffer management table has columns of priority, QCI (Qos Class Identifier), retention amount threshold value, untransmitted data retention amount, retention time threshold value, and untransmitted data retention time. .

In the priority column, UEs that perform CA are stored. In the example of FIG. 17, the higher the priority stored in the UE, the higher the priority for performing CA.
The QCI field stores the QCI of the UE. The UE QCI is included in the E-RAB Level QoS Parameters of the message notified from the MME 33 when the bearer is set up.

  In the retention amount threshold value column, a buffer retention amount threshold value is stored. The staying amount threshold is determined based on, for example, QCI. For example, as shown in FIG. 17, if the QCI is “2”, the staying amount threshold is “50”. Note that the setting of the staying amount threshold can be arbitrarily changed. For example, if the QCI is “2”, the staying amount threshold may be changed to “60”.

  The residence time threshold field stores a residence time threshold for untransmitted data stored in the buffer. The residence time threshold is determined based on, for example, QCI. For example, as shown in FIG. 17, if the QCI is “2”, the residence time threshold is “150”. The residence time threshold value can be arbitrarily changed. For example, if the QCI is “2”, the residence time threshold may be changed to “160”.

  For example, the call processing control unit 62 determines the priority order of UEs that perform CA based on the ratio of the untransmitted data retention amount to the retention amount threshold and the ratio of the untransmitted data retention time to the retention time threshold. For example, the call processing control unit 62 adds the ratio of the untransmitted data retention amount to the retention amount threshold and the ratio of the untransmitted data retention time to the retention time threshold, and increases the priority as the UE has a higher addition value. . In addition, when there are a plurality of UEs having the same ratio, the call processing control unit 62 determines the priority order based on the QCI.

Note that the above-described determination of exceeding the threshold value in step S65 is made based on the values in the stay amount threshold value and stay time threshold fields.
Returning to the description of FIG. [Step S67] The call processing control unit 62 assigns 0 to the variable i.

  [Step S68] The call processing control unit 62 refers to the transmission buffer management table and selects a UE that exceeds the staying amount threshold and the staying time threshold. At this time, the call processing control unit 62 selects UEs in descending order of priority.

  The call processing control unit 62 selects a frequency band to be monitored by the selected UE. For example, it is assumed that the call processing control unit 62 selects the UE 34. The call processing control unit 62 selects, as the monitoring frequency band, a frequency band that matches the frequency band in which the selected UE 34 can perform radio communication and the frequency band of the cell of the own station (eNB 31). Further, the call processing control unit 62 selects a frequency band that matches the frequency band in which the selected UE 34 can perform radio communication and the frequency band of the cell of the other station (eNB 32) as the monitoring frequency band.

  FIG. 18 is a diagram for explaining selection of a monitoring frequency band. FIG. 18 shows a monitoring frequency band selection table. For example, the monitoring frequency band selection table is formed in the memory 51d shown in FIG. As shown in FIG. 18, the monitoring frequency band selection table has columns of own station frequency band information, other station frequency band information, and UE frequency band information.

  The frequency band of the cell formed by the eNB 31 is stored in the own station frequency band information column. The frequency band information of the cell formed by the eNB 32 is stored in the other station frequency band information column. That is, the frequency bands in which each of the eNBs 31 and 32 can communicate are stored in the respective columns of the local station frequency band information and the other station frequency band information. For example, according to the example of FIG. 6, information on frequency bands as shown in FIG. 18 is stored in the fields of own station frequency band information and other station frequency band information of FIG.

  In the field of UE frequency band information, frequency band information capable of performing radio communication of UEs belonging to the eNB 31 is stored. If the example of FIG. 6 is followed, the information as shown in FIG. 18 will be stored in the UE frequency band information column of FIG.

  The frequency band in which the radio communication of the UE 34 can be performed can be acquired by, for example, the process of step S11 illustrated in FIG. In the process of step S11, the call processing control unit 62 receives capability information of the UE 34 from the UE 34, and acquires a frequency band in which the radio communication of the UE 34 can be performed from the received capability information. Then, the call processing control unit 62 stores the acquired frequency band in the monitoring frequency band selection table.

  As described above, the call processing control unit 62 selects, as the monitoring frequency band, a frequency band that matches the frequency band in which the UE 34 can perform radio communication and the frequency band of its own cell. Further, the call processing control unit 62 selects a frequency band that matches the frequency band in which the UE 34 can perform radio communication and the frequency band of the cell of the other station as the monitoring frequency band. For example, in the case of FIG. 18, the call processing control unit 62 selects the frequency bands f2 and f3 as monitoring frequency bands. The frequency band f1 is not selected because it is used as Pcell. That is, the call processing control unit 62 selects a frequency band in which the UE 34 can wirelessly communicate with the eNBs 31 and 32.

  Note that when selecting the monitoring frequency band, the call processing control unit 62 may sequentially select a frequency band close to the Pcell frequency band as the monitoring frequency band. For example, in FIG. 18, the frequency bands in which the UE 34 can perform radio communication are f1 to f4. Further, it is assumed that there is a relationship of f1 <f2 <f3 <f4. In this case, the call processing control unit 62 selects the monitoring frequency band from the frequency bands f2, f3, f4 and the frequency band close to Pcell. Thereby, UE34 can process the several frequency band which adjoined, for example, and can reduce a load.

  Returning to the description of FIG. [Step S69] The call processing control unit 62 determines whether or not the variable i is smaller than the variable I. The variable I is the number of frequency bands in which the UE 34 can perform radio communication. For example, in the example of the UE 34 in FIG. 18, I is “3”.

[Step S70] If the variable i is equal to or greater than the variable I, the call processing control unit 62 stops the monitoring process of the UE 34.
[Step S71] The call processing control unit 62 instructs the BB processing unit 63 to monitor the frequency band selected in Step S68.

[Step S72] The BB processing unit 63 makes a monitoring request for the frequency band selected in step S68 via the wireless unit 64.
[Step S73] The BB processing unit 63 receives the monitoring response (result) of the frequency band from the UE 34 via the radio unit 64.

[Step S74] The call processing control unit 62 receives the monitoring result of the frequency band from the BB processing unit 63.
[Step S75] Based on the monitoring result received from the BB processing unit 63, the call processing control unit 62 determines whether the UE 34 has detected the frequency band designated by the monitoring instruction. When the call processing control unit 62 determines that the UE 34 has detected the frequency band specified by the monitoring instruction, the call processing control unit 62 determines that “UE 34 can perform radio communication in the frequency band specified by the monitoring instruction”, and proceeds to step S77. If the call processing control unit 62 determines that the frequency band designated by the UE 34 in the monitoring instruction has not been detected, the call processing control unit 62 proceeds to step S76.

Note that the call processing control unit 62 detects the frequency bands f2 and f3 in the example of FIGS.
[Step S76] The call processing control unit 62 adds 1 to the variable i.

[Step S77] The call processing control unit 62 performs Scell addition processing.
Note that the monitoring request in step S72 corresponds to, for example, the process in step S15 in FIG. The monitoring response in step S73 corresponds to, for example, the process in step S17 in FIG. Moreover, the frequency band detection and Scell addition processing of steps S75 and S77 correspond to, for example, the processing of the dotted line frame D11 in FIG. 8 and the dotted line frame D12 in FIG.

Scell radio resource allocation request processing will be described.
FIG. 19 is a sequence diagram illustrating a Scell radio resource allocation request process. The sequence diagram of FIG. 19 corresponds to the processing of steps S23 to S25 of FIG.

  [Step S81] The call processing control unit 62 of the eNB 31 makes a radio resource allocation request to the call processing control unit of the eNB 32 via the transport unit 61. At this time, the call processing control unit 62 transmits, to the eNB 32, radio resource allocation information expected from the Scell of the eNB 32.

For example, the call processing control unit 62 transmits information on an RB (Resource Block) to be allocated to the UE 34 and its cycle to the eNB 32.
In addition, the call processing control unit 62 transmits the UE information of the UE 34 to be CA to the eNB 32. The UE information is, for example, the QCI, retention amount threshold, untransmitted data retention amount, retention time threshold, and untransmitted data retention time of the transmission buffer management table shown in FIG.

In addition, the call processing control unit 62 transmits the identifier (UE-ID) of the UE 34 to be CA to the eNB 32.
Further, the call processing control unit 62 transmits to the eNB 32 a Cell-ID that allows the UE 34 to wirelessly communicate with the eNB 32 of another station. For example, this Cell-ID is the ID of the cell 43 (frequency band f3) of the eNB 32 detected in step S75 of FIG.

  [Step S82] The call processing control unit of the eNB 32 determines whether or not radio resource allocation is possible based on the radio resource allocation information received from the eNB 31. For example, the call processing control unit determines whether or not radio resources of the UE 34 can be allocated depending on whether or not there is a vacancy in the RB of the frequency band f3 of the eNB 32.

  At this time, the call processing control unit of the eNB 32 considers the priority order of the UE and the UE 34 that are under the control of the own station (eNB 32) based on the UE information of the UE 34 received from the eNB 31. Judge whether allocation is possible. For example, even if the frequency band f3 of the eNB 32 is available, the call processing control unit determines whether to allocate radio resources if the priority of the UE 34 is lower than that of other UEs.

  [Step S83] The call processing control unit of the eNB 32 transmits a response indicating whether or not radio resources can be allocated to the eNB 31 via the transport unit. The call processing control unit of the eNB 32 transmits the identifier of the UE 34 that has determined whether or not radio resources can be allocated when transmitting a response indicating whether or not radio resources can be allocated.

  Note that the call processing control unit 62 of the eNB 31 allocates the radio resource of the eNB 32 to the UE 34 based on the radio resource allocation information expected of the eNB 32. The radio resource information of the eNB 32 allocated to the UE 34 is transmitted to the eNB 32 together with the data transfer of the UE 34 by the BB processing unit 63 as described later.

  Moreover, the allocation information of the radio | wireless resource anticipated in Scell of eNB32 demonstrated by step S81 is changed by the change detection of the radio | wireless resource of eNB32. Also, the radio resource allocation information expected in the Scell of the eNB 32 described in step S81 is released by detecting the release of the radio resource of the eNB 32.

  In the above sequence, the eNBs 31 and 32 have described the case of exchanging data through the X2 interface based on X2AP. However, the eNB 31 and 32 may exchange data through the S1 interface based on S1AP. That is, the eNBs 31 and 32 may exchange data via the MME 33.

  FIG. 20 is a diagram for explaining determination of priority order in other stations. A transmission buffer management table 71 illustrated in FIG. 20 illustrates a transmission buffer management table stored in the memory 51d of the eNB 31. The transmission buffer management table 72 is a transmission buffer management table stored in the memory of the eNB 32 of another station.

  The UE information of the UE 34 is transmitted to the eNB 32 as described in step S81 of FIG. The UE information transmitted to the eNB 32 is stored in the transmission buffer management table 72 of the eNB 32. For example, as indicated by an arrow A <b> 11 in FIG. 20, UE information of the UE 34 is stored in the transmission buffer management table 72 of the eNB 32. Note that UE # 2 in FIG. 20 corresponds to UE34.

  The call processing control unit of the eNB 32 determines the priority order of the UE 34 based on the transmission buffer management table 72. In the example of FIG. 20, the priority of UE34 (UE # 2) is the highest. Therefore, for example, if the RB of the frequency band f3 is free, the call processing control unit of the eNB 32 returns a response indicating that radio resources can be allocated to the eNB 31.

Data transfer processing delay measurement processing will be described.
FIG. 21 is a sequence diagram showing processing delay measurement processing for data transfer. The sequence diagram of FIG. 21 corresponds to the processing of steps S27 to S29 of FIG.

  [Step S91] The BB processing unit 63 of the eNB 31 gives a time T1 at the time of transmission to a GTP-u (General packet radio service Tunneling Protocol for user plane) message.

  [Step S <b> 92] The BB processing unit 63 transmits a GTP-u message to which the time T <b> 1 is given to the eNB 32 via the transport unit 61. At this time, the BB processing unit 63 assigns a TE-ID (Tunnel Endpoint IDentifier) for the eNB 32 so that the eNB 32 receives the message. In addition, TE-ID of eNB32 is notified from eNB32 in the process of FIG.19 S83, for example.

[Step S93] The BB processing unit of the eNB 32 gives a time T2 at the time of transmission of the message to the GTP-u message.
[Step S94] The BB processing unit of the eNB 32 transmits a GTP-u message with the time T2 to the eNB 31 via the transport unit. At this time, the BB processing unit gives the time T1 included in the message received from the eNB 31. Further, the BB processing unit gives a TE-ID for the eNB 31 so that the message is received by the eNB 31. In addition, TE-ID of eNB31 is notified from eNB31 in the process of FIG.19 S81, for example.

  [Step S95] The BB processing unit 63 of the eNB 31 calculates a processing delay time Δt. That is, the BB processing unit 63 calculates the time required for data transfer from the eNB 31 to the eNB 32. For example, the BB processing unit 63 calculates Δt by the following equation (1).

Δt = T2−T1 (1)
Note that Δt calculated by the BB processing unit 63 is notified to the call processing control unit 62. The call processing control unit 62 performs scheduling of the UE 34 based on Δt notified from the BB processing unit 63. For example, the call processing control unit 62 schedules radio resource allocation and transmission timing for the UE 34 based on Δt.

  The above sequence shows the operation when the X2 interface is established between the eNBs 31 and 32. Hereinafter, a case where the X2 interface is not established will be described.

FIG. 22 is another sequence diagram showing a data transfer processing delay measurement process. The sequence diagram of FIG. 22 corresponds to the processing of steps S27 to S29 of FIG. 9, for example.
[Step S101] The BB processing unit 63 of the eNB 31 adds a time T1 at the time of transmission to the GTP-u message.

  [Step S102] The BB processing unit 63 transmits a GTP-u message to which the time T1 is given to the eNB 32 via the transport unit 61. At this time, the BB processing unit 63 gives a TE-ID for the MME 33 so that the message is received by the MME 33.

[Step S103] The MME 33 changes the TE-ID of the message received from the eNB 31 to the TE-ID for the eNB 32.
[Step S104] The MME 33 transmits a message in which the TE-ID is changed to the eNB 32.

[Step S105] The BB processing unit of the eNB 32 assigns a time T2 at the time of transmission of the message to the GTP-u message.
[Step S106] The BB processing unit of the eNB 32 transmits a GTP-u message to which the time T2 is given to the MME 33 via the transport unit. At this time, the BB processing unit gives the time T1 included in the message received from the eNB 31. Further, the BB processing unit gives a TE-ID for the MME 33 so that the message is received by the MME 33.

[Step S107] The MME 33 changes the TE-ID of the message received from the eNB 32 to the TE-ID for the eNB 31.
[Step S108] The MME 33 transmits a message in which the TE-ID is changed to the eNB 31.

[Step S109] The BB processing unit 63 of the eNB 31 calculates a processing delay time Δt. For example, the BB processing unit 63 calculates Δt by the above equation (1).
Thus, even when the X2 interface is not established, the processing delay time by the S1 interface can be measured by the above sequence.

The CA process will be described.
FIG. 23 is a first diagram illustrating the CA process. FIG. 23 illustrates a buffer included in the eNB 31 at a certain time Tx and radio resource allocation (horizontal axis t, vertical axis f (number of RBs)) of the eNB 31. The UE # 2 buffer of the eNB 31 illustrated in FIG. 23 indicates, for example, a buffer that temporarily stores transmission data of the UE 34 illustrated in FIG. The UE # 1 buffer is, for example, a buffer that temporarily stores transmission data of the UE that is not illustrated in FIG. The CA buffer is a buffer for temporarily storing data to be CA. The transfer buffer is a buffer that temporarily stores data to be transferred to the eNB 32.

  Also, FIG. 23 illustrates a buffer included in the eNB 32 and radio resource allocation (horizontal axis t, vertical axis f (number of RBs)) of the eNB 32. The UE # 3 and # 4 buffers of the eNB 32 illustrated in FIG. 23 are buffers that temporarily store transmission data of the UE (not illustrated in FIG. 6), for example. The CA buffer is a buffer for temporarily storing data to be CA. The process flow shown in FIG. 23 corresponds to, for example, the processes in steps S33 and S34 in FIG.

  Data to be sent to the UE is usually assigned radio resources as soon as scheduling is determined. For example, as shown in the UE # 1 buffer of FIG. 23 and the radio resource allocation shown below, the data to be transmitted to UE # 1 is allocated radio resources as soon as scheduling is determined.

  On the other hand, data whose staying amount and staying time exceed a predetermined threshold is not immediately assigned to a radio resource even if scheduling is determined. For example, it is assumed that the data transmitted to the UE 34 (UE # 2) has a staying amount and a staying time that exceed a predetermined threshold. In this case, data to be transmitted to UE # 2 is queued in the CA buffer and the transfer buffer as indicated by arrows A21 and A22.

Data 81a and 81b indicate transmission data of the queued UE 34.
Data 82 indicates scheduling information of the data 81a and 81b. The data 82 indicates, for example, Pcell PDSCH scheduling of the eNB 31 and Scell PDSCH scheduling of the eNBs 31 and 32.

The data 83 is information indicating at which timing the data 81a and 82 are transmitted to the UE 34. That is, the data 83 indicates a time for queuing the data 81a and 82 stored in the CA buffer. Information data 83, for example, S FN (System Frame Number) for transmitting data 81a, 82, a subframe number, and RB assignment information. The SFN and subframe number are determined based on ΔT calculated by Expression (1). That is, the eNB 31 allocates the data 81a and 82 to the radio resource after a predetermined time of ΔT or ΔT + α, and transmits the data to the UE 34.

  The data 84 is information indicating at which timing the data 81b is transmitted to the UE 34. Data 84 shows the same contents as data 83. That is, the data 81b is transmitted from the eNB 32 to the UE 34 at the same timing as the data 81a.

  The data 81b and 84 are transferred to the eNB 32 as a GTP-u message as soon as they are queued in the transfer buffer. The time required to transfer the data 81b and 84 is Δt.

FIG. 24 is a second diagram illustrating the CA process. FIG. 24 shows a state after a predetermined time (after ΔT or ΔT + α) in FIG.
A dotted line frame 91 shown in FIG. 24 indicates the data 81a described in FIG. That is, the data 81 a queued in the CA buffer is assigned to a radio resource after a predetermined time based on the data 83 and transmitted to the UE 34.

  A dotted line frame 92 indicates the data 82 described with reference to FIG. That is, scheduling information queued in the CA buffer and transmitted to the UE 34 on the PDCCH is assigned to a radio resource after a predetermined time based on the data 83 and is transmitted to the UE 34.

  The data 93 and 94 are the data 81b and 84 described with reference to FIG. That is, the data 93 and 94 are data transferred from the eNB 31. The data 93 is assigned to a radio resource after a predetermined time based on the data 94 indicating the same content as the data 83 and is transmitted to the UE 34. A dotted line frame 95 indicates data 93 assigned to the radio resource.

That is, the data 81a, 81b, 82 described in FIG. 23 is transmitted to the UE 34 in consideration of the delay time of the data 81b transferred to the eNB 32.
A dotted frame 92 indicates scheduling information transmitted to the UE 34 by PDCCH. Therefore, the data indicated by the dotted line frames 91 and 95 are allocated to the RBs along the scheduling information of the dotted line frame 92 as indicated by arrows A31 and A32.

  Scheduling of data to be transmitted to the UE is performed by the call processing control unit 62. For example, the call processing control unit 62 schedules RB allocation and transmission timing for the UE 34.

  Based on the scheduling of the call processing control unit 62, for example, the BB processing unit 63 allocates data stored in the buffers illustrated in FIGS. 23 and 24 to radio resources and transmits the radio resources to the UE. Further, the BB processing unit 63 transfers a part of data to be transmitted to the UE to the eNB 32 of another station as illustrated in FIG.

The BB processing unit of the eNB 32 receives data transferred from the eNB 32. The BB processing unit of the eNB 32 allocates the received data to the radio resource based on the S FN , the subframe number, and the RB assignment information included in the received data, and transmits the radio resource to the UE 34.

The call processing control unit of the eNB 32 receives in advance the allocation information of radio resources expected from the Scell of the eNB 32 from the eNB 31 (for example, step S81 in FIG. 19), and secures radio resources to be allocated to the UE 34. Therefore, the BB processing unit of the eNB 32 can assign radio resources to the UE 34 based on the S FN received from the eNB 31, the frame number, and the RB assignment information.

  The call processing control unit 62 and the BB processing unit 63 correspond to, for example, the transmission unit 1a in FIG. The call processing control unit 62 and the BB processing unit 63 correspond to, for example, the transfer unit 1b in FIG. The BB processing unit of the eNB 32 corresponds to, for example, the receiving unit 2a and the transmitting unit 2b in FIG.

FIG. 25 is a diagram illustrating a data format example of data transferred to the eNB of another station. FIG. 25 shows the Extension Header of the GTP-u message.
Normally, “0” is stored in the Next Extension Header Type of the GTP-u message. When using the Extension Header, a value other than “0” is stored in the Next Extension Header Type field. For example, as shown in FIG. 25, “0x01” is stored. The Extension Header Length is stored in the second octet of the Extension Header.

  For example, as shown in FIG. 25, the SFN is stored in the third to fourth octets of the Extension Header. The subframe number is stored in the fourth octet of the Extension Header. The RB assignment information is stored in the Extension Header from the 5th octet to the (n-1) th octet.

  Note that the user message is stored in the area following the Extension Header of the GTP-u message. That is, data to be transferred to the eNB 32 is stored in an area following the extension header.

  FIG. 26 is a diagram illustrating a data flow in the downlink layer. FIG. 26 illustrates the layer 101 of the eNB 31, the layer 102 of the eNB 32, and the layer 103 of the UE 34. As shown in FIG. 26, the layer 101 of the eNB 31 has GTP-u, PDCP (Packet Data Convergence Protocol), RLC (Radio Link Control), MAC (Medium Access Control), and L1 (Layer 1) layers. ing. The layer 102 of the eNB 32 has GTP-u, PDCP, RLC, MAC, and L1 layers. The layer 103 of the UE 34 has PDCP, RLC, MAC, and L1 layers.

  A dotted arrow A41 shown in FIG. 26 indicates the flow of PDCCH data. The PDCCH data is transmitted to the UE 34 via the Pcell of the eNB 31 as indicated by the dotted arrow A41.

  An arrow A42 indicates the flow of PDSCH data via Pcell. The PDSCH data is transmitted to the UE 34 via the Pcell of the eNB 31 as indicated by an arrow A42.

  Arrow A43 indicates the flow of PDSCH data via Scell. The PDSCH data is transmitted to the UE 34 via the Scell of the eNB 31 and the Scell of the eNB 32 of the other station as indicated by an arrow A43. Data transferred from the eNB 31 to the eNB 32 is transferred from the MAC layer to the GTP-u layer and transferred to the GTP-u layer of the eNB 32 in the eNB 31.

A case where the end timing of CA between the eNBs 31 and 32 is detected in the Pcell will be described. The following process corresponds to, for example, the process of the dotted frame D13 in FIG.
The call processing control unit 62 of the eNB 31 makes a CA stop request to the BB processing unit 63 when the retention amount and the retention time of data to be transmitted to the UE 34 are equal to or less than a predetermined threshold. In response to the CA stop request from the call processing control unit 62, the BB processing unit 63 stops data transmission by the CA. Further, the BB processing unit 63 stops data transfer to the other eNB 32.

  Similarly, the call processing control unit 62 issues a CA stop request to the BB processing unit of the eNB 32. The BB processing unit of the eNB 32 receives the CA stop request from the call processing control unit 62, stops the CA, and releases the Scell.

A case where there is a CA radio resource change request in the Scell of another station will be described. The following process corresponds to, for example, the process of the dotted frame D14 in FIG.
The call processing control unit of the eNB 32 detects a change in the radio resource assigned to the UE 34. For example, since a UE having a higher priority than the UE 34 exists, the call processing control unit of the eNB 32 detects a change in the radio resource when a part of the radio resource allocated to the UE 34 is allocated to the UE.

  The call processing control unit of the eNB 32 makes a radio resource change request to the call processing control unit 62 of the eNB 31. At this time, for example, the call processing control unit of the eNB 32 notifies the call processing control unit 62 of the eNB 31 of radio resource information (for example, RB assignment information) to be allocated to the UE 34. The call processing control unit 62 receives a radio resource change request from the eNB, changes the radio resource assigned to the UE 34, and returns a response to the eNB 32. The call processing control unit of the eNB 32 receives the response from the eNB 31 and changes the radio resource allocation information of the UE 34. For example, the call processing control unit of the eNB 32 changes information on radio resources expected from the eNB 31.

A case where there is a CA radio resource release request in the Scell of another station will be described. The following process corresponds to, for example, the process of the dotted frame D15 in FIG.
The call processing control unit of the eNB 32 detects the release of the radio resource assigned to the UE 34. For example, since a UE having a higher priority than the UE 34 exists, the call processing control unit of the eNB 32 detects the release of the radio resource when assigning the radio resource assigned to the UE 34 to the UE.

  The call processing control unit of the eNB 32 makes a radio resource release request to the call processing control unit 62 of the eNB 31. The call processing control unit 62 of the eNB 31 receives the radio resource release request from the eNB and releases the Scell of the eNB 32. The call processing control unit 62 returns a radio resource release request response to the eNB 32. The call processing control unit 62 notifies the UE 34 that the Scell of the eNB 32 has been released.

The call processing control unit of the eNB 32 receives the response of the radio resource release request from the eNB 31 and allocates the radio resource allocated to the UE 34 to the UE having a high priority.
The change of Pcell will be described.

  The call processing control unit 62 of the eNB 31 changes the Pcell to a cell in a frequency band with good communication quality. For example, when the UE 34 moves, the frequency band with good communication quality changes. In this case, the call processing control unit 62 of the eNB 31 changes the cell in the frequency band with the best communication quality to Pcell.

  As described above, the call processing control unit 62 and the BB processing unit 63 of the eNB 31 transfer part of the data to be transmitted to the CA to the eNB 32 so that the data transmission to the UE 34 is performed in the eNB 32 of the other station. . In addition, the BB processing unit of the eNB 32 receives the data transferred by the eNB 31 and transmits it to the UE 34. Thereby, the eNB 31 adds the frequency band of the eNB 32 of the other station to its own CA and performs data transmission to the UE 34, so that it is possible to increase the speed and capacity of the data communication.

  Further, the call processing control unit 62 and the BB processing unit 63 of the eNB 31 stop the data transmission to the UE 34 when the staying amount and staying time of the data to be transmitted to the UE 34 are equal to or less than a predetermined threshold, and the data to the eNB 32 Stop the transfer. Thereby, eNB31 can allocate a radio | wireless resource appropriately to subordinate UE.

  Further, the call processing control unit 62 of the eNB 31 changes the radio resource allocation of the UE 34 in response to a request from the eNB 32 of another station. Further, the call processing control unit 62 of the eNB 31 notifies the UE 34 that the cell that has performed radio communication with the eNB 32 has been released in response to a request from the eNB 32 of another station. Thereby, eNB32 can allocate a radio | wireless resource appropriately to subordinate UE.

  The above merely illustrates the principle of the present invention. In addition, many modifications and changes can be made by those skilled in the art, and the present invention is not limited to the precise configuration and application shown and described above, and all corresponding modifications and equivalents may be And the equivalents thereof are considered to be within the scope of the invention.

1, 2 Base station 1a, 2b Transmitter 1b Transfer unit 2a Receiver 3 Wireless terminal

Claims (9)

  A transmitter that transmits data to a wireless terminal using a plurality of frequency bands;
  A transfer unit that transfers a part of data transmitted by the transmission unit to the other base station so that data transmission to the wireless terminal is performed in the other base station;
  With
  The transmission unit starts data transmission by the plurality of frequency bands based on both or one of the retention amount and the retention time of data to be transmitted to the wireless terminal,
  The base station, wherein the transfer unit starts data transfer based on both or one of the staying amount and the staying time.   A request unit that makes a radio resource allocation request whether or not radio resources can be allocated to the radio terminal to the other base station;
  A receiving unit that receives a result of whether or not radio resources of the radio terminal can be allocated from the other base station;
  The base station according to claim 1, further comprising:   3. The base station according to claim 2, wherein the request unit transmits, to the other base station, information including a resource block to be allocated to the radio terminal and a cycle thereof when the radio resource allocation request is made.   A measuring unit for measuring a time required for data transfer of the transfer unit;
  A scheduling unit that performs scheduling of the wireless terminal based on the time measured by the measurement unit;
  The base station according to claim 1, further comprising:   A storage unit storing a frequency band in which the wireless terminal can communicate, a frequency band in which the base station can communicate, and a frequency band in which the other base station can communicate;
  With reference to the storage unit, a selection unit that selects a frequency band in which the wireless terminal can wirelessly communicate with the base station and the other base station,
  A monitor unit that allows the radio terminal to monitor whether radio communication can be performed with the base station and the other base station in the frequency band selected by the selection unit;
  The base station according to claim 1, comprising:   The base station according to claim 5, wherein the selection unit selects a frequency band close to a frequency band of a primary cell of the transmission unit.   The transmission unit stops data transmission by the plurality of frequency bands based on both or one of the retention amount and the retention time of data to be transmitted to the wireless terminal,
  The base station according to claim 1, wherein the transfer unit stops data transfer based on both or one of the staying amount and the staying time.   The base station according to claim 1, further comprising a changing unit that changes assignment of radio resources of the radio terminal in response to a radio resource change request from the other base station.   In addition, the wireless terminal further includes a notification unit that notifies the wireless terminal that a cell that has performed wireless communication with the other base station has been released in response to a request for releasing a radio resource from the other base station. The base station according to claim 1.

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