JP5879662B2 - Mobile station apparatus, network control apparatus, communication system, control method, and control program - Google Patents

Description

  The present invention relates to a mobile station device, a network control device, a communication system, a control method, and a control program.

  In 3GPP (3rd Generation Partnership Project), specifications of LTE-A (Long Term Evolution-Advanced) are currently being studied. LTE-A is required to realize higher-speed communication than LTE, and is required to support a wider band (a band up to 100 MHz exceeding the 20 MHz band of LTE) than LTE. However, it is difficult to secure a worldwide continuous wide frequency range for LTE-A. Therefore, in order to maintain the compatibility with LTE as much as possible, it has been studied to perform communication by collecting a plurality of frequency bands called component carriers (CC: Component Carrier) whose bandwidth is up to 20 MHz. In the communication, a carrier aggregation (CA) technique that secures a maximum bandwidth of 100 MHz and realizes high-speed and large-capacity communication has been studied.

  The component carrier used in the communication using the CA technology is allocated in a UE-specific manner from the base station when CA communication is started or reconfigured. A serving cell that performs communication is configured by a combination of one PCell (Primary Serving Cell) and one or more SCells (Secondary Serving Cells). The PCell communicates control information (C-Plane: Control Plane) and data information (U-Plane: User Plane). Here, the component carrier corresponding to PCell is called PCC (Primary Component Carrier). The SCell performs communication of only data information (U-Plane). Here, the component carrier corresponding to SCell is called SCC (Secondary Component Carrier) (refer to Section 7.5 of Non-Patent Document 1).

  The SCC has a configuration state and a non-configuration state. Furthermore, the configure state includes an activate state and a deactivate state. When CA is not performed, all the cells other than the PCell are in a non-configured state. When performing CA, SCell is added. At this time, the added SCC is in a deactivated configure state. In the deactivated state, quality measurement such as CQI (Channel Quality Indicator) is performed so that communication can be performed immediately, but communication of the individual channel itself does not occur. When the radio quality from the deactivated SCell reported from the mobile station is improved, the base station changes to the activated state and starts communication.

  When the mobile station changes the PCell during communication, the change is performed by handover using a random access procedure. At this time, it is agreed at the 3GPP RAN2 # 70bis meeting that the SCC is once deactivated, communication with the SCC is terminated, and if necessary, a new PCell is connected and then the SCC is activated again.

GPP TS 36.300 V11.0.0 (2011-12)

  Currently, 3GPP is examining carrier aggregation (CA) between different base stations. When the UE is stationary (or moves at a low speed) in the area of the picocell base station while CA is implemented using the picocell base station in the communication area of the macrocell base station and the macrocell base station. think of. When the macro cell base station is continuously used as the PCC, there is a problem in that the use of the user concentrates on the macro cell base station 100, thereby increasing the load on the macro cell base station and causing congestion.

  Therefore, the present invention has been made in view of the above problems, and it is an object to provide a mobile station device, a network control device, a communication system, a control method, and a control program that can reduce the possibility of congestion. And

  (1) The present invention has been made in view of the above circumstances, and one aspect of the present invention has a communication range that overlaps a communication range of a macro cell base station and the macro cell base station, and the communication range is larger than the macro cell base station. The mobile station apparatus includes a determination unit that determines that a primary component carrier is allocated to the picocell base station based on information related to movement of the own mobile station apparatus within a communication range of both picocell base stations.

  (2) In the mobile station apparatus described above, according to one aspect of the present invention, the determination unit determines that the allocation of a primary component carrier is changed from the macro cell base station to the pico cell base station.

  (3) In the mobile station apparatus described above, one aspect of the present invention determines that a primary component carrier is allocated to the picocell base station and a secondary component carrier is allocated to the macrocell base station.

  (4) In the mobile station apparatus described above, according to one aspect of the present invention, the information on the movement is a movement speed of the own apparatus, and the determination unit is based on the movement speed of the own mobile station apparatus. It determines with assigning a primary component carrier to the said picocell base station.

  (5) In the mobile station apparatus described above, one aspect of the present invention is that the determination unit is configured to transmit a primary component to the picocell base station based on a moving speed of the mobile station apparatus and reception quality of a secondary component carrier. It is determined that a carrier is allocated.

  (6) In the mobile station apparatus described above, one aspect of the present invention is that the determination unit is configured to determine a difference between a moving speed of the mobile station apparatus and a reception quality of a primary component carrier and a reception quality of a secondary component carrier. And determining that a primary component carrier is allocated to the picocell base station.

  (7) In the mobile station apparatus described above, according to one aspect of the present invention, the determination unit includes: a moving speed of the own mobile station apparatus; a difference between reception quality of a primary component carrier and reception quality of a secondary component carrier; It is determined that a primary component carrier is allocated to the picocell base station based on a comparison with a threshold corresponding to the moving speed of the own mobile station device.

  (8) In the mobile station apparatus described above, according to one aspect of the present invention, the information on the movement is a position of the own mobile station apparatus, and the determination unit is based on the position of the own mobile station apparatus. It determines with assigning a primary component carrier to the said picocell base station.

  (9) One aspect of the present invention is based on information related to movement of a mobile station apparatus in a communication range of both a macro cell base station and a pico cell base station having a communication range overlapping the communication range of the macro cell base station. It is a network control apparatus provided with the determination part determined to allocate a primary component carrier to a base station.

  (10) In the network control device described above, according to one aspect of the present invention, the information on the movement is a movement speed of a mobile station apparatus, and the determination unit is configured to perform the operation based on the movement speed of the mobile station apparatus. It determines with assigning a primary component carrier to a picocell base station.

  (11) In the network control device described above, according to an aspect of the present invention, the determination unit is configured to transmit a primary component carrier to the picocell base station based on a moving speed of the mobile station device and a reception quality of a secondary component carrier. Is determined to be assigned.

  (12) In the network control device described above, according to one aspect of the present invention, the determination unit is based on a moving speed of the mobile station device and a difference between reception quality of a primary component carrier and reception quality of a secondary component carrier. Then, it is determined that a primary component carrier is allocated to the picocell base station.

  (13) In the network control device described above, according to one aspect of the present invention, the determination unit includes: a moving speed of the mobile station device; a difference between reception quality of a primary component carrier and reception quality of a secondary component carrier; It is determined that a primary component carrier is allocated to the picocell base station based on a comparison with a threshold corresponding to the moving speed of the mobile station device.

  (14) In the network control device described above, according to one aspect of the present invention, the information on the movement is a position of a mobile station device, and the determination unit is configured to generate the pico cell based on the position of the mobile station device. It is determined that a primary component carrier is allocated to the base station.

  (15) One aspect of the present invention has a communication range that overlaps with a communication range of a macrocell base station and the macrocell base station, and is in a communication range of both picocell base stations having a communication range narrower than the macrocell base station The communication system includes a determination unit that determines to allocate a primary component carrier to the picocell base station based on information related to movement of a station apparatus.

  (16) In one aspect of the present invention, the determination unit has a communication range that overlaps with a communication range of a macro cell base station and the macro cell base station, and communication between both pico cell base stations having a communication range narrower than the macro cell base station. It is a control method including a procedure for determining that a primary component carrier is allocated to the picocell base station based on information related to movement of a mobile station device within a range.

  (17) According to one aspect of the present invention, a computer has a communication range overlapping a macro cell base station and a communication range of the macro cell base station, and a communication range of both pico cell base stations having a communication range narrower than the macro cell base station A control program for executing a step of determining that a primary component carrier is allocated to the picocell base station based on information related to movement of the mobile station apparatus in FIG.

  According to the present invention, the possibility of congestion can be reduced.

It is the schematic of the communication system in 1st Embodiment. It is a schematic block diagram which shows the structure of the communication system in 1st Embodiment. It is a sequence diagram which shows an example of the process of the communication system in 1st Embodiment. 3 is a flowchart illustrating an example of a process flow of a mobile station in the first embodiment. It is a schematic block diagram which shows the structure of the communication system in 2nd Embodiment. It is a schematic block diagram which shows the structure of the communication system 1c in 3rd Embodiment. It is a sequence diagram which shows an example of the process of the communication system in 3rd Embodiment. It is a flowchart which shows an example of the flow of a process of the core network control apparatus in 3rd Embodiment. It is a schematic block diagram which shows the structure of the communication system in 4th Embodiment. It is a sequence diagram which shows an example of the process of the communication system in 4th Embodiment.

<First Embodiment>
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a schematic diagram of a communication system according to the first embodiment. In the figure, a picocell base station 200 is arranged in a macrocell 11 which is a communication area of the macrocell base station 100. The picocell base station 200 is a base station having a communication range that overlaps the communication range of the macrocell base station 100 and having a communication range narrower than that of the macrocell base station 100. The picocell base station 200 is a small base station having a communication range with a radius of several meters to several tens of meters, and mainly used indoors. Each base station is connected to a core network control device (also referred to as a network control device) 300 that controls the base station. In CA communication, control information and data information are transmitted via PCC, and only data information is transmitted via SCC.

  Next, an outline of the present embodiment will be described. In the present embodiment, a mobile station (hereinafter also referred to as a mobile station apparatus or a terminal apparatus) 500 measures the movement speed of its own mobile station, and if the measured movement speed is zero or low, the mobile station (PCC) 500 And switch the SCC assignment. Here, the low speed is a speed equal to or lower than a predetermined threshold speed. The macro cell base station 100 switches allocation of PCC and SCC with the pico cell base station 200 based on the switching request. That is, the macro cell base station 100 changes the assignment of the macro cell base station 100 from PCC to SCC and the assignment of the pico cell base station 200 from SCC to PCC.

In the initial setting of the present embodiment, as an example, the component carrier A (CC_A: Component Carrier_A) used by the macrocell base station 100 is assumed to be PCC. Here, CC_A uses frequency band 1. Macrocell base station 100 communicates with CC_A.
In the initial setting, as an example, the component carrier B (CC_B: Component Carrier_B) used by the picocell base station 200 is set as the SCC. Here, CC_B uses a frequency band 2 different from the frequency band 1 as an example. The picocell base station 200 communicates with CC_B.
With this assumption, it is assumed that the mobile station 500 moves (moves at a low speed) after moving from the position P1 to the position P2 in the picocell 12 which is the communication area of the picocell base station 200 as shown in FIG. This will be described below.

FIG. 2 is a schematic block diagram illustrating a configuration of the communication system according to the first embodiment. In FIG. 1, the communication system 1 includes a macro cell base station 100, a pico cell base station 200, a core network control device 300, and a mobile station 500.
The mobile station 500 includes an antenna 511, an antenna 521, an antenna 531, an antenna 541, a P reception unit 512, an S reception unit 522, a P transmission unit 532, an S transmission unit 542, a control unit 551, a speed detection unit 561, and a cell determination unit 571. Is provided. Antennas 511, 521, 531 and 541 are radio communication antennas. It should be noted that only the components necessary for the description of the present embodiment are shown as the components of the mobile station 500, and description and illustration of the components used for normal wireless communication provided in the other mobile stations 500 are omitted.

The macrocell base station 100 includes antennas 111 and 121, an A transmission unit 112, an A reception unit 122, and a control unit 131. The antennas 111 and 112 of the macro cell base station are radio communication antennas.
The picocell base station 200 includes antennas 211 and 221, a B transmission unit 212, a B reception unit 222, and a control unit 231. The antennas 211 and 212 of the picocell base station are radio communication antennas.
The core network control device 300 includes a control unit 311.
In addition, as the components of the macro cell base station 100, the pico cell base station 200, and the core network control device 300, only those necessary for the description of the present embodiment are shown, and the other macro cell base station 100, the pico cell base station 200, and the core network control device are shown. Description and illustration of components used for normal wireless communication provided in the apparatus 300 are omitted.

Hereinafter, processing of the communication network 1 of the present embodiment will be described. First, processing of each unit included in the mobile station 500 will be described.
The P receiving unit 512 receives a signal transmitted from the antenna 111 of the macrocell base station 100 via the antenna 511. Then, the P receiving unit 512 drops the received signal to the baseband, performs a Fourier transform on the digital signal after AD conversion, and a signal in the frequency band of CC_A from the signal on the frequency axis after the Fourier transform. Extract. The P receiving unit 512 demodulates and decodes the extracted CC_A signal. Thereby, the P receiving unit 512 can restore the signal transmitted from the macro cell base station 100. Then, the P receiver 512 outputs the decoded signal to the controller 551.

  The S reception unit 522 receives a signal transmitted from the antenna 211 of the picocell base station 200 via the antenna 521. Then, the S receiver 522 drops the received signal to the baseband, performs a Fourier transform on the digital signal after AD conversion, and a signal in the frequency band of CC_B from the signal on the frequency axis after the Fourier transform. Extract. The S receiver 522 demodulates and decodes the extracted CC_B signal. Thereby, the S receiver 522 can restore the signal transmitted from the macrocell base station 100. Then, the S reception unit 522 outputs the decoded signal to the control unit 551.

  Based on the control by the control unit 551, the P transmission unit 532 encodes the signal input from the control unit 551 and modulates the encoded signal. Then, the P transmission unit 532 superimposes the modulated signal on CC_A. Then, the P transmission unit 532 performs inverse Fourier transform on the superimposed signal. Then, P transmission section 532 transmits a signal based on the signal after inverse Fourier transform from antenna 531 to antenna 121 of macro cell base station 100.

  The S transmission unit 532 encodes the signal input from the control unit 551 based on the control by the control unit 551 and modulates the encoded signal. Then, the S transmission unit 532 superimposes the modulated signal on the CC_B frequency band. Then, the S transmission unit 532 performs an inverse Fourier transform on the superimposed signal. Then, the S transmission unit 532 DA-converts a signal based on the signal on the time axis after the inverse Fourier transform and then up-converts the signal to a radio frequency band, and transmits the signal from the antenna 541 to the antenna 221 of the picocell base station 200. To do.

The speed detector 561 detects the moving speed of the mobile station 500 at a predetermined cycle, for example. Specifically, for example, the speed detection unit 561 detects the moving speed of the mobile station 500 by the following process. The speed detection unit 561 includes, for example, an acceleration sensor, and holds stride information indicating the stride of the user who moves while holding the mobile station 500. The speed detection unit 561 detects, for example, the walking pitch of the user during a predetermined detection period (for example, 10 seconds) using an acceleration sensor. And the speed detection part 561 detects the moving speed of the mobile station 500, for example by dividing the value which multiplied the step by the walking pitch by the detection period which detected the walking pitch. Note that the method of detecting the moving speed in the speed detecting unit 561 is not limited to this.
Then, the speed detection unit 561 outputs movement speed information indicating the detected movement speed to the control unit 551. Then, the control unit 551 outputs the movement speed information input from the speed detection unit 561 to the cell determination unit 571.

The cell determination unit 571 determines whether or not it is within the communication range of both the macrocell base station 100 and the picocell base station 200. When the cell determination result indicates that the cell determination result is within the communication range of both the macro cell base station 100 and the pico cell base station 200, the cell determination unit 571 performs the following processing.
The cell determination unit 571 determines to change the assignment of the primary component carrier from the macro cell base station 100 to the pico cell base station 200 based on the movement speed indicated by the movement speed information input from the speed detection unit 561. More specifically, the cell determination unit 571 determines that a primary component carrier is allocated to the picocell base station 200 and a secondary component carrier is allocated to the macrocell base station 100 based on the moving speed. In other words, the cell determination unit 571 determines whether to switch the allocation of the primary component carrier and the secondary component carrier between the macrocell base station 100 and the picocell base station 200 based on the moving speed.

  Specifically, for example, when the moving speed is slower than a predetermined threshold speed, that is, when moving at a low speed, the cell determination unit 571 assigns a primary component carrier to the picocell base station 200 and sets a secondary component carrier to the macrocell base station 100. Is determined to be assigned. This is because when the mobile station 500 detects the stationary or low-speed movement of the mobile station 500, it can be considered that the mobile station 500 stays in the area of the picocell base station 200 for a long time. Here, when the moving speed is slower than a predetermined threshold speed, it is assumed that the stop is included.

  Cell determination unit 571 outputs a switching instruction signal for instructing switching between PCC and SCC to control unit 551. In addition, the cell determination unit 571 holds PCC base station information indicating a base station to which a PCC is assigned and SCC base station information indicating a base station to which an SCC is assigned.

  The control unit 551 switches data to be output to the P transmission unit 532 and the S transmission unit 542 in accordance with switching between PCC and SCC indicated by the switching instruction signal input from the cell determination unit 571. Specifically, for example, when the mobile station 500 is moving at a high speed, the PCC is assigned to the macro cell base station 100, so the control unit 551 outputs control information and data information to the P transmission unit 532. . Here, the high speed is a speed exceeding a predetermined threshold speed. On the other hand, when the assignment of the PCC and the SCC is switched and the SCC is assigned to the macro cell base station 100, the control unit 551 outputs only the data information to the P transmission unit 532.

  For example, when the mobile station 500 is moving at high speed, since the SCC is assigned to the picocell base station 200, the control unit 551 outputs only the data information to the S transmission unit 542. On the other hand, when the mobile station 500 is stationary (or moves at a low speed), the mobile station 500 switches the assignment between the PCC and the SCC, and the PCC is assigned to the picocell base station 200. The information is output to the P transmission unit 532.

Subsequently, processing of each unit of the macrocell base station 100 will be described.
First, the process of the macrocell base station 100 when the mobile station 500 is moving at high speed will be described. Since PCC is assigned to the macro cell base station 100, the macro cell base station 100 communicates control information and data information with the mobile station 500.
The control unit 131 outputs control information and data information to the A transmission unit 112 and controls the A transmission unit 112. The A transmission unit 112 encodes control information and data information under the control of the control unit 131, and modulates the encoded signal. The A transmission unit 112 superimposes the modulated signal on the CC_A frequency band, and transmits the signal from the antenna 111 to the mobile station 500 after DA conversion and up-conversion to the radio frequency band.

The A receiver 122 receives a signal transmitted from the mobile station 500 via the antenna 121. The A receiving unit 122 drops the signal transmitted from the P transmitting unit 532 of the mobile station 500 to the baseband, performs AD conversion, performs Fourier transform (FFT: Fast Fourier Transform) on the converted digital signal, and after Fourier transform The signal in the frequency band of CC_A is extracted from the signal on the frequency axis. Then, the A receiving unit 122 demodulates the extracted signal and decodes the demodulated signal. Thereby, the A receiving unit 122 restores the control information and data information transmitted from the mobile station 500. The A receiving unit 122 outputs the restored control information and data information to the control unit 131.
The control unit 131 communicates with the core network control device 300 and performs processing related to handover (HO).

Next, processing of each unit of the macro cell base station 100 when an SCC is assigned to the macro cell base station 100 by handover (HO) will be described. Since the SCC is assigned to the macro cell base station 100, in this case, the macro cell base station 100 performs communication of only data information with the mobile station 500.
The control unit 131 has the same function as when the PCC is assigned to the macrocell base station 100, but differs in the following points. The control unit 131 outputs only data information to the A transmission unit 112.
The A transmission unit 112 has the same function as when the PCC is assigned to the macrocell base station 100, but differs in the following points. That is, the A transmission unit 112 encodes only the data information according to the control of the control unit 131.
The A receiving unit 122 has the same function as when the PCC is assigned to the macrocell base station 100, but differs in the following points. That is, in the A receiving unit 122, the decoded signal includes only data information. The A receiving unit 122 outputs the data information to the control unit 131.

Subsequently, processing of each unit of the picocell base station 200 will be described.
First, each part of the picocell base station 200 when the SCC is assigned to the picocell base station 200 will be described. When the SCC is assigned to the picocell base station 200, the picocell base station 200 performs communication only with data information with the mobile station 500.

  The control unit 231 outputs data information to the B transmission unit 212 and controls the B transmission unit 212. The B transmission unit 212 encodes data information and modulates the encoded signal under the control of the control unit 231. The B transmission unit 212 superimposes the modulated signal on the CC_B frequency band. The B transmission unit 212 performs inverse Fourier transform on the superimposed signal. The B transmission unit 212 generates a transmission signal by performing DA conversion and up-conversion to a radio frequency band based on the signal after the inverse Fourier transform. Then, the B transmission unit 212 transmits a transmission signal from the antenna 211 to the mobile station 500.

  The B receiver 222 receives a signal transmitted from the mobile station 500 via the antenna 221. The B receiver 222 drops the signal transmitted from the S transmitter 542 of the mobile station 500 to the baseband, performs a Fourier transform on the digital signal after AD conversion, and a signal in the frequency band of CC_B from the signal after the Fourier transform To extract. Then, the B receiving unit 222 demodulates the extracted signal and decodes the demodulated signal. Thereby, the B receiving unit 222 restores the data information transmitted from the mobile station 500. The B receiving unit 222 outputs the restored data information to the control unit 231.

  Subsequently, when there is a PCC / SCC switching request from the mobile station 500 to the macro cell base station 100, the control unit 231 performs communication regarding handover (HO) with the core network control apparatus 300. .

Next, processing of each unit of the picocell base station 200 when a PCC is assigned to the picocell base station 200 by handover (HO) will be described.
The control unit 231 has the same function as when the SCC is assigned to the picocell base station 200, but differs in the following points. That is, the control unit 231 outputs control information and data information to the B transmission unit 212.
The B transmission unit 212 has the same function as when the SCC is assigned to the picocell base station 200, but differs in the following points. That is, the B transmission unit 212 encodes control information and data information.

  The B receiving unit 222 has the same function as when the SCC is assigned to the picocell base station 200, but differs in the following points. That is, the output of the B receiver 222 includes control information and data information that are signals obtained after demodulation. The B receiving unit 222 outputs the control information and the data information to the control unit 231.

  The control unit 311 of the core network control apparatus 300 controls communication between the macrocell base station 100 and the picocell base station 200. For example, when receiving a HO request from the macro cell base station 100, the control unit 311 controls communication regarding the HO between the macro cell base station 100 and the pico cell base station 200. Details of the processing of the control unit 311 will be described later.

  FIG. 3 is a sequence diagram illustrating an example of processing of the communication system 1 according to the first embodiment. The mobile station 500 uses the macro cell base station 100 as the PCC (CC_A) and the pico cell base station 200 as the SCC (CC_B), performs the speed detection periodically while performing CA communication, Move from P1 to position P2. At this time, the cell determination unit 571 of the mobile station 500 stores that the picocell base station is used as the SCC. Then, when the mobile station 500 stops (or moves at a low speed) at the position P2 in FIG. 1, it is determined that the mobile station 500 stays in the area of the picocell base station 200 for a while. Then, mobile station 500 changes picocell base station 200 from SCC that transmits only data information to PCC that transmits control information and data information. Specifically, for example, the communication system 1 operates as follows.

First, in T101, the mobile station 500 communicates with the macrocell base station 100 by PCC. In parallel with T102, mobile station 500 communicates with picocell base station 200 using SCC.
Next, in T103, the mobile station 500 measures the moving speed of the mobile station 500 while grasping that CA communication is performed using the picocell base station as the SCC. Since the moving speed is high, the cell determination unit 571 determines not to switch between PCC and SCC. Here, the high speed is a speed exceeding a predetermined threshold speed, for example.

Next, in T104, the mobile station 500 communicates with the macrocell base station 100 by PCC. In parallel with T105, mobile station 500 communicates with picocell base station 200 by SCC.
Next, in T106, the mobile station 500 measures the moving speed of the mobile station 500. Since the moving speed is zero, that is, the mobile station 500 is stationary, the cell determination unit 571 of the mobile station 500 determines to switch between PCC and SCC.

  Next, at T107, since the mobile station 500 detects the low speed of the mobile station 500, the mobile station 500 notifies the macro cell base station 100 of a switching request to use CC_B used as the SCC as the PCC. Here, the switching request notification includes switching information for using which frequency band of the PCC as the SCC and also using the SCC as the PCC. Note that the speed of the mobile station 500 is not limited to a low speed, and even when the mobile station 500 is stationary, the mobile station 500 notifies the switching request so that CC_B used as the SCC is used as the PCC.

Next, in T108, the macro cell base station 100 receives the switching request notification from the mobile station 500, and transmits a HO request to the core network control apparatus 300 so as to switch CC_B from SCC to PCC.
Next, in T109, the core network control apparatus 300 determines whether or not HO is possible from the resource status of the picocell base station 200 in response to the HO request received from the macrocell base station 100. Core network control apparatus 300 then notifies HO request to picocell base station 200 if HO is possible.

  Next, the picocell base station 200 prepares for HO according to the HO request from the core network control apparatus 300. Next, in T110, the picocell base station 200 notifies the core network control apparatus 300 of a HO response for permitting HO after completing the HO preparation.

  Next, in T111, the core network control apparatus 300 notifies the macro cell base station 100 of the HO response received from the pico cell base station 200. Next, in T112, after receiving the HO response, the macro cell base station 100 transmits the HO response to the mobile station 500.

  Next, in T113, the mobile station 500 that has received the HO request from the macrocell base station 100 transmits a random access request to the picocell base station 200 in order to perform HO to the picocell base station 200. Next, in T114, the picocell base station 200 transmits a random access response to the mobile station 500 in response to the random access request received from the mobile station 500.

Next, when the HO process to the pico cell base station 200 is completed at T115, the pico cell base station 200 transmits a HO completion response to the macro cell base station 100 to the core network control apparatus 300.
Next, in T116, the core network control apparatus 300 transmits the received HO completion response to the macro cell base station 100.
Next, in T117, the mobile station 500, the macrocell base station 100, and the picocell base station 200 switch between PCC and SCC assignment.

  Next, in T118, the mobile station 500 starts communication with the macrocell base station 100 using the SCC. In parallel with this, at T119, the mobile station 500 starts communication with the picocell base station 200 using the PCC. Above, the process of this sequence is complete | finished.

FIG. 4 is a flowchart illustrating an example of a process flow of the mobile station 500 according to the first embodiment. First, in step S <b> 101, the mobile station 500 executes CA with the PCC assigned to the macrocell base station 100 and the SCC assigned to the picocell base station 200.
Next, in step S102, the cell determination unit 571 determines whether or not the SCC is assigned to the picocell base station 200. When the SCC is not assigned to the picocell base station 200 (NO in step S102), the control unit 551 maintains the communication in which the PCC is assigned to the picocell base station 200, and returns to the process of step S101.

On the other hand, when the SCC is assigned to the picocell base station 200 (YES in step S102), the control unit 551 acquires the moving speed of the mobile station 500 from the speed detecting unit 561 (step S104), and proceeds to the process of step S105. move on.
Next, in step S105, the cell determination unit 571 determines whether the moving speed is zero or low. When the moving speed is not zero or not low (NO in step S105), the cell determination unit 571 determines that the PCC maintains communication assigned to the macrocell base station 100, and returns to the process of step S101.

  On the other hand, when the moving speed is zero or low in step S105 (YES in step S105), the cell determination unit 571 determines switching between assignment of PCC and SCC (step S107). Next, in step S108, the control unit 551 notifies the macro cell base station 100 of a switching request through PCC. Next, in step S109, the control unit 551 receives the HO response transmitted from the macrocell base station 100 by PCC.

  Next, in step S110, the control unit 551 performs HO processing for transmitting a random access request to the picocell base station 200. Next, when the HO process is completed, in step S111, the control unit 551 switches the assignment between the PCC and the SCC. That is, the control unit 551 sets CC_B as PCC and CC_A as SCC. Above, the process of this flowchart is complete | finished.

<Effect of the first embodiment>
As described above, the mobile station 500 in the first embodiment detects the moving speed of the mobile station 500 while the macrocell base station 100 and the picocell base station 200 are executing CA. Then, when detecting the stationary or low speed, the mobile station 500 determines to change the base station to which the PCC is allocated from the macro cell base station 100 to the pico cell base station 200. The mobile station 500 executes this process even if the communication quality of the macrocell base station is better than the communication quality of the picocell base station 200.

  Thereby, since the macrocell base station 100 can distribute the load to the picocell base station 200, the load on the macrocell base station 100 can be reduced. In addition, it is possible to reduce the concentration of users on the macrocell base station 100, and to reduce the possibility of congestion.

  In addition, the conventional macro cell base station has a problem that resource allocation cannot be sufficiently performed because there is a possibility that many users use the macro cell base station having a large cell size. On the other hand, according to the present embodiment, the resources of the macro cell base station 100 are opened by assigning the PCC to the pico cell base station 200, so that a large number of users can use the macro cell base station 100. In addition, the speed detection unit 561 of the first embodiment has an advantage that it can be realized at low cost using an acceleration sensor.

  In this embodiment, the mobile station 500 determines whether or not to switch the assignment of PCC and SCC based only on the moving speed of the mobile station 500, and switches the assignment of PCC and SCC when stationary (or low speed). However, this is not a limitation.

  The cell determination unit 571 of the mobile station 500 may determine whether to switch the assignment of the PCC and the SCC based on the periodically measured moving speed, the reception quality of the PCC, and the reception quality of the SCC. Here, RSRP (Reference Signal Received Power), RSRQ (Reference Signal Received Quality) or path loss may be used as the reception quality.

  When the speed detection unit 561 detects stationary (or low speed movement) as the movement speed, the cell determination unit 571 checks the reception quality of the PCC and SCC. If the difference between the PCC reception quality and the SCC reception quality is within the threshold value Sp [dB] (P−S ≦ Sp), the cell determination unit 571 uses CC_B used as the SCC as the PCC. May be notified of the switching request.

  Alternatively, the measurement report may be transmitted to the macro cell base station 100 when the cell determination unit 571 detects P−S ≦ Sp. In that case, the macro cell base station 100 may operate by determining the Measurement Report as a switching request from the mobile station 500.

  Here, the value of the threshold value Sp may be changed according to the moving speed. For example, when the mobile station 500 is stationary (or moving at a low speed), the cell determination unit 571 may increase the value of the threshold value Sp compared to that at the medium speed. Here, the low speed is, for example, a speed that is equal to or lower than a predetermined first threshold speed, and the medium speed is, for example, a speed that is faster than the first threshold speed, and is a predetermined second speed. The speed is equal to or less than the threshold speed (however, faster than the first threshold speed). As a result, the cell determination unit 571 can easily satisfy the switching condition, and the mobile station 500 can easily request the core network control device 300 to switch between the PCC and the SCC.

Further, the threshold Sp may tend to increase as the moving speed of the mobile station 500 decreases. Further, the control unit 551 may set the value of the threshold value Sp in consideration of not only the moving speed but also the value specific to each base station depending on the cell size and the like.
As a method for notifying the mobile station 500 of the value of the threshold value Sp, it may be stored in the broadcast information of each base station, or may be notified to the mobile station 500 by a Measurement Control message.

  In summary, the cell determination unit 571 determines to allocate the primary component carrier to the picocell base station 200 based on the moving speed of the mobile station 500 and the difference between the reception quality of the primary component carrier and the reception quality of the secondary component carrier. To do. More specifically, the cell determination unit 571 is based on a comparison between the moving speed of the mobile station 500, the difference between the reception quality of the primary component carrier and the reception quality of the secondary component carrier, and a threshold corresponding to the moving speed of the mobile station 500. Thus, it is determined that the primary component carrier is allocated to the picocell base station 200.

  Further, for example, the cell determination unit 571 performs primary control to the picocell base station 200 when the mobile station 500 moves at a low speed (or is stationary) and the reception quality of the secondary component carrier is better than a predetermined threshold reception quality. It is determined that a component carrier is allocated. That is, the cell determination unit 571 may determine to allocate a primary component carrier to the picocell base station 200 based on the moving speed of the mobile station 500 and the reception quality of the secondary component carrier.

<Second Embodiment>
Next, the second embodiment will be described. In the first embodiment, the mobile station 500 determines that the mobile station 500 is stationary (or moves at a low speed) by detecting the moving speed of the mobile station 500. The mobile station 500b in the second embodiment determines that it is stationary (or moves at a low speed) by periodically performing GPS (Global Positioning System) positioning instead of speed detection.

  FIG. 5 is a schematic block diagram showing the configuration of the communication system 1b in the second embodiment. Elements common to those in FIG. 2 are denoted by the same reference numerals, and detailed description thereof is omitted. The configuration of the communication system 1b in FIG. 5 is such that the mobile station 500 is changed to the mobile station 500b with respect to the configuration of the communication system 1 in FIG. The configuration of the mobile station 500b in FIG. 5 is the same as the configuration of the mobile station 500 in FIG. 2 except that the speed detection unit 561 is deleted, the GPS reception unit 581 is added, and the control unit 551 is changed to the control unit 551b. The cell determination unit 571 is changed to a cell determination unit (determination unit) 571b.

The GPS receiving unit 581 measures the current position of the mobile station 500 at a predetermined cycle by receiving radio waves from a plurality of GPS satellites and determining the distances between them. Here, the current position includes latitude and longitude. Then, the GPS receiving unit 581 outputs position information indicating the current position of the mobile station 500 to the control unit 551b.
The control unit 551b has the same function as the control unit 551 of the first embodiment, but differs in the following points. The control unit 551b outputs the position information input from the GPS reception unit 581 to the cell determination unit 571b.

  The cell determination unit 571b determines whether or not the mobile station 500 stays in the picocell base station 200 based on the position information input from the control unit 551b. When it is determined that the mobile station 500 is staying in the picocell base station 200, the cell determination unit 571b switches between PCC and SCC allocation, allocates SCC to the macrocell base station 100, and allocates PCC to the picocell base station 200. Is determined. Then, the cell determination unit 571b outputs a switching instruction signal for instructing switching of allocation of PCC and SCC to the control unit 551b.

  Then, when the cell determination unit 571b receives a switching instruction signal, the control unit 551b requests the macro cell base station 100 to switch the assignment of PCC and SCC. Thereby, the macrocell base station 100 executes a process of switching the PCC and SCC allocation with the picocell base station 200 based on the switching request.

  As described above, in view of the processing of the first embodiment and the second embodiment, the cell determination unit (571 or 571b) is configured so that the mobile station (500 or 500) in the communication range of both the macrocell base station 100 and the picocell base station 200 can be used. 500b) functions as a determination unit that determines to allocate a primary component carrier to the picocell base station 200 based on the information related to movement. Here, the information regarding movement includes the speed or position of the mobile station (500 or 500b).

<Effects of Second Embodiment>
In the second embodiment, the information related to the movement of the mobile station 500b is the position of the mobile station 500b. The cell determination unit 571b determines to allocate a primary component carrier to the picocell base station 200 based on the position of the mobile station 500b.

  Thereby, since the macrocell base station 100 can distribute the load to the picocell base station 200, the load on the macrocell base station 100 can be reduced. In addition, it is possible to reduce the concentration of users on the macrocell base station 100, and to reduce the possibility of congestion.

In addition, the conventional macro cell base station has a problem that resource allocation cannot be sufficiently performed because there is a possibility that many users use the macro cell base station having a large cell size. On the other hand, according to the present embodiment, the resources of the macro cell base station 100 are opened by assigning the PCC to the pico cell base station 200, so that a large number of users can use the macro cell base station 100.
According to the second embodiment, since the mobile station 500b detects the position by GPS, the allocation of the primary component carrier and the secondary component carrier is switched according to the position instead of the speed. Therefore, the mobile station 500b of the second embodiment can perform the switching determination more appropriately than the mobile station 500 of the first embodiment.

<Third Embodiment>
Subsequently, a third embodiment will be described. In the first embodiment, the mobile station 500 detects the moving speed of the mobile station 500 itself, and determines whether to switch the assignment of PCC and SCC based on the detected moving speed. On the other hand, in the third embodiment, the macro cell base station 100 measures the moving speed and reports the moving speed to the core network control apparatus (network control apparatus) 300c. When the moving speed is zero or low, the core network control apparatus 300c determines to switch the PCC and SCC to the macrocell base station 100.

  FIG. 6 is a schematic block diagram showing the configuration of the communication system 1c in the third embodiment. Elements common to those in FIG. 2 are denoted by the same reference numerals, and detailed description thereof is omitted. The configuration of the communication system 1c in FIG. 6 is different from the configuration of the communication system 1 in FIG. 2 in that the mobile station 500 is changed to the mobile station 500c and the macrocell base station 100 is changed to the macrocell base station 100c. 300 is changed to the core network control device 300c.

  Hereinafter, an outline of processing of the communication system 1 according to the third embodiment will be described. When the moving speed of the mobile station 500 is reported from the macro cell base station 100c to zero (or low speed), the core network control apparatus 300c performs the following processing. The core network control apparatus 300c confirms the resource status of the picocell base station 200c and transmits a switching request notification to the macrocell base station 100 so that CC_B used as SCC is used as PCC if HO is possible. The switching request notification includes switching information for indicating which frequency band of the PCC is used as the SCC and which SCC is used as the PCC.

The configuration of the mobile station 500b in FIG. 6 is the same as the configuration of the mobile station 500 in FIG. 2 except that the speed detection unit 561 and the cell determination unit 571 are deleted and the control unit 551 is changed to the control unit 551c. Yes.
Further, the configuration of the macro cell base station 100c in FIG. 6 is such that a speed detection unit 141 is added to the configuration of the macro cell base station 100 in FIG. 2 and the control unit 131 is changed to the control unit 131c. .
The speed detector 141 detects the moving speed of the mobile station 500c at a predetermined cycle, for example. For example, the moving speed of the mobile station 500c is detected based on a reference signal periodically transmitted from the mobile station 500c. Specifically, for example, assuming that the mobile station 500c has moved in the radial direction from the macrocell base station 100c, the moving speed of the mobile station 500c is set based on the change in the power of the reference signal received from the mobile station 500c. To detect. Then, the speed detection unit 141 outputs movement speed information indicating the detected movement speed to the control unit 131c.

  The control unit 131c has the same function as the control unit 131 of the first embodiment, but differs in the following points. That is, the control unit 131c outputs the movement speed information from the speed detection unit 141 to the core network control apparatus 300c. In addition, the control unit 131c outputs first presence information indicating whether or not the mobile station 500c exists in the macro cell to the core network control apparatus 300c.

The configuration of the pico cell base station 200c in FIG. 6 is such that the control unit 231 is changed to a control unit 231c with respect to the configuration of the pico cell base station 200 in FIG.
The control unit 231c has the same function as the control unit 231 of the first embodiment, but differs in the following points. That is, the control unit 231c outputs the second presence information indicating whether or not the mobile station 500c exists in the pico cell to the core network control apparatus 300c.

  The configuration of the core network control device 300c in FIG. 6 is a configuration in which the control unit 311 is changed to the control unit 311c and a cell determination unit (determination unit) 321 is added to the configuration of the core network control device 300 in FIG. It has become.

  The control unit 311c has the same function as the control unit 311 of the first embodiment, but differs in the following points. The control unit 311c outputs the first presence information received from the macro cell base station 100c to the cell determination unit 321. In addition, the control unit 311c outputs the second presence information received from the picocell base station 200c to the cell determination unit 321. In addition, the control unit 311c outputs the moving speed information received from the macro cell base station 100c to the cell determination unit 321.

Based on the first presence information input from the macrocell base station 100c and the second presence information input from the picocell base station 200c, the cell determination unit 321 allows the mobile station 500c to perform the macrocell base station 100 and the picocell base station 200c. It is determined whether or not both communication ranges are present. When it is determined that the cell determination unit 321 is within the communication range of both the macro cell base station 100 and the pico cell base station 200c, the cell determination unit 321 is based on the moving speed of the mobile station 500c indicated by the moving speed information input from the control unit 311c. It is determined whether or not a primary component carrier is allocated to the station 200c.
On the other hand, when it is determined that the cell determination unit 321 is not within the communication range of both the macro cell base station 100 and the pico cell base station 200, the cell determination unit 321 does not determine whether or not to assign a primary component carrier to the pico cell base station 200c.

Specifically, for example, when the moving speed is slower than a predetermined threshold speed, that is, when the moving speed is low, the cell determining unit 321 determines whether to allocate a primary component carrier to the picocell base station 200c. Here, when the moving speed is slower than a predetermined threshold speed, it is assumed that the stop is included. The cell determination unit 321 outputs a switching instruction signal instructing switching between PCC and SCC to the control unit 311c. When the switching instruction signal is input from the cell determination unit 321, the control unit 311 c notifies the macro cell base station 100 c of a switching request.
In addition, the cell determination unit 321 holds PCC base station information indicating a base station to which a PCC is allocated and SCC base station information indicating a base station to which an SCC is allocated.

  FIG. 7 is a sequence diagram illustrating an example of processing of the communication system 1c according to the third embodiment. In the sequence of FIG. 1, it is assumed that the mobile station 500c moves from the position P11 of FIG. 1 to the position P12 while performing CA communication by assigning the macrocell base station 100c to the PCC and assigning the picocell base station 200 to the SCC. The macrocell base station 100c periodically measures the moving speed of the mobile station 500c and reports it to the core network control apparatus 300c. The core network control device 300c monitors the moving speed result from the macrocell base station 100 while grasping that the CA communication is performed using the picocell base station 200c as the SCC. Here, the core network control device 300c stores in the cell determination unit 321 that the mobile station 500c uses the picocell base station 200c as the SCC.

  When the mobile station 500c is stationary (or moves at a low speed) at the position P12 in FIG. 1, the core network control device 300c determines that the mobile station 500c stays in the area of the picocell base station 200c for a while. Then, the communication system 1c changes the picocell base station 200 from SCC that transmits only data information to PCC that transmits control information and data information. Details of the above processing will be described below.

  First, in T201, the mobile station 500c communicates with the macrocell base station 100c as PCC. Next, in T202, in parallel with T201, the mobile station 500c communicates with the picocell base station 200c as SCC. Next, in T203, the macro cell base station 100c reports the speed detection result to the core network control apparatus 300c.

Next, in T204, the cell determination unit 321 of the core network control apparatus 300c determines that the allocation of PCC and SCC is not switched when the moving speed is high from the speed detection result received from the macrocell base station 100c.
Next, in T205, the mobile station 500c communicates with the macrocell base station 100c as PCC. Next, in T206, in parallel with T205, the mobile station 500c communicates with the picocell base station 200c as SCC. Next, in T207, the macro cell base station 100c reports the speed detection result to the core network control apparatus 300c.

  Next, in T208, from the speed detection result, when the moving speed of the mobile station 500c is zero, that is, when the mobile station 500c is stationary, the cell determination unit 321 of the core network control apparatus 300c assigns the PCC and the SCC. Is determined to be switched.

  Next, in T209, the core network control apparatus 300c transmits a switch request notification to the macro cell base station 100 so that CC_B used as the SCC is used as the PCC. Next, in T211, a switching request notification is transmitted to the mobile station 500c by PCC (CC_A).

Next, in T211, the core network control apparatus 300c requests HO from the picocell base station 200c. As a result, the picocell base station 200 prepares for HO according to the HO request from the core network control apparatus 300.
Next, at T212, the picocell base station 200c transmits a HO response to permit the HO to the core network control apparatus 300c after completing the HO preparation. Next, in T213, the core network control apparatus 300c transmits the HO response received from the picocell base station 200c to the macrocell base station 100c.

  Next, when the macro cell base station 100c receives the HO response at T214, the macro cell base station 100c transmits the HO response to the mobile station 500c. Next, in T215, the mobile station 500c makes a random access request to the picocell base station 200c in order to perform HO to the picocell base station 200.

  Next, in T216, the picocell base station 200c transmits a random access response to the mobile station 500c in response to the random access request. At T217, when the random access process is completed, the picocell base station 200c transmits to the core network control apparatus 300 a HO completion response indicating that the HO process is completed to the macrocell base station 100. Then, at T218, the core network control apparatus 300 transmits the HO completion response received from the picocell base station 200c to the macrocell base station 100c.

  Next, in T219, the mobile station 500c, the macrocell base station 100c, and the picocell base station 200c switch base stations to which PCC and SCC are allocated. Thereby, in T220, the macrocell base station 100c starts communication with the mobile station 500c by SCC. Further, at T221, the picocell base station 200 starts communication with the mobile station 500c by PCC. Above, the process of this sequence is complete | finished.

FIG. 8 is a flowchart illustrating an example of a processing flow of the core network control apparatus 300c in the third embodiment. The processing of the core network control apparatus 300c in this flowchart is the same processing as the processing of the mobile station 500 in FIG.
First, in step S <b> 201, the mobile station 500 executes CA with the PCC assigned to the macrocell base station 100 and the SCC assigned to the picocell base station 200.
Next, in step S202, the cell determination unit 321 of the core network control apparatus 300c determines whether or not an SCC is assigned to the picocell base station 200. When the SCC is not assigned to the picocell base station 200 (NO in step S202), the mobile station 500 maintains the communication in which the PCC is assigned to the picocell base station 200, and returns to the process of step S201.

On the other hand, when the SCC is assigned to the picocell base station 200 (YES in step S202), the cell determination unit 321 acquires the moving speed of the mobile station 500 from the speed detecting unit 141 of the macrocell base station 100c (step S204). The process proceeds to step S205.
Next, in step S205, the cell determination unit 321 determines whether the moving speed is zero or low. When the moving speed is not zero or low (NO in step S205), the cell determination unit 571 determines that the PCC maintains the communication assigned to the macrocell base station 100c, and returns to the process of step S201.

  On the other hand, when the moving speed is zero or low in step S205 (YES in step S205), the cell determination unit 321 determines switching between assignment of PCC and SCC (step S207). Next, in step S208, the macrocell base station 100c notifies the switching request to the mobile station 500c by PCC (corresponding to T210 in FIG. 7). Next, in step S209, the macro cell base station 100c transmits a HO request to the mobile station 500c by PCC (corresponding to T214 in FIG. 7).

  Next, in step S210, the mobile station 500 performs HO processing for transmitting a random access request to the picocell base station 200 (corresponding to T215 in FIG. 7). Next, when the HO process is completed, in step S211, the mobile station 500c, the macro cell base station 100c, and the pico cell base station 200c switch assignment of PCC and SCC. That is, the mobile station 500c, the macro cell base station 100c, and the pico cell base station 200c set CC_B as PCC and CC_A as SCC. Above, the process of this flowchart is complete | finished.

<Effect of the third embodiment>
As described above, the macro cell base station 100 c in the third embodiment detects the moving speed of the mobile station 500 c while the mobile station 500 c is executing CA in the macro cell base station 100 c and the pico cell base station 200 c. Then, when the cell determination unit 321 of the core network 300c detects the stationary or low-speed movement of the mobile station 500c, it determines that the base station to which the PCC is assigned is changed from the macrocell base station 100c to the picocell base station 200c. The mobile station 500c executes this process even if the communication quality of the macrocell base station is better than the communication quality of the picocell base station 200.

Thereby, since the macro cell base station 100c can distribute a load to the pico cell base station 200c, the load of the macro cell base station 100c can be reduced. In addition, it is possible to reduce the concentration of users on the macrocell base station 100c, and to reduce the possibility of congestion.
Further, according to the configuration of the third embodiment, since the mobile station 500c does not detect the speed or position, the load on the mobile station 500c can be reduced.

  In addition, the conventional macro cell base station has a problem that resource allocation cannot be sufficiently performed because there is a possibility that many users use the macro cell base station having a large cell size. On the other hand, according to this embodiment, the resources of the macro cell base station 100c are opened by allocating the PCC to the pico cell base station 200c, so that a large number of users can use the macro cell base station 100.

  Note that, in the third embodiment, as in the first embodiment, the cell determination unit 321 determines whether to switch the assignment of PCC and SCC based only on the moving speed of the mobile station 500c. Not a thing. The cell determination unit 321 may perform determination in consideration of not only the moving speed but also a value unique to each base station, such as a cell size.

In addition, the macro cell base station 100c may determine whether the cell determination unit 321 switches the assignment of the PCC and the SCC based on the moving speed of the mobile station 500c, the reception quality of the PCC, and the reception quality of the SCC. This determination process may be realized by the following process. The macro cell base station 100c may confirm the PCC reception quality and the SCC reception quality from the Measurement Report message from the mobile station 500c, respectively. Here, the quality of each base station may be confirmed using RSRP (Reference Signal Received Power), RSRQ (Reference Signal Received Quality), or path loss.
When the macrocell base station 100 detects that the mobile station 500c is stationary (or low-speed movement), the result of the movement speed indicating that the mobile station 500c is stationary (or low-speed movement), the reception quality of the PCC, and the reception quality of the SCC Report to the controller 300c.

  The core network control device 300c confirms the moving speed result received from the macrocell base station 100, the reception quality of the PCC, and the reception quality of the SCC. If the difference between the reception quality of the PCC and the reception quality of the SCC is within the threshold value Sp [dB] (PS ≦ Sp), the core network control device 300c uses the CC_B used as the SCC to the macrocell base station 100 to the PCC. The switching request may be notified so as to be used as

  Alternatively, the macro cell base station 100c determines whether or not the difference between the moving speed, the PCC reception quality, and the SCC reception quality is within the threshold Sp [dB]. If the moving speed is zero (or low speed) and the difference in reception quality is within the threshold value Sp [dB] (PS ≦ Sp), the macrocell base station 100c uses CC_B used as SCC as PCC. The switching request may be notified to the core network control device 300c.

  Here, the value of the threshold value Sp may be changed according to the moving speed. For example, in the case of stationary or low-speed movement, the value of the threshold value Sp may be larger than that at medium speed. This makes it easier to satisfy the conditions for requesting the core network control device 300 to switch between PCC and SCC. Further, the threshold Sp may be changed so as to decrease as the moving speed of the mobile station 500c decreases.

  In summary, the cell determination unit 321 assigns a primary component carrier to the picocell base station 200c based on the moving speed of the mobile station device and the difference between the reception quality of the primary component carrier and the reception quality of the secondary component carrier. It may be determined whether or not. More specifically, the cell determination unit 321 is based on a comparison between the moving speed of the mobile station apparatus, the difference between the reception quality of the primary component carrier and the reception quality of the secondary component carrier, and a threshold corresponding to the moving speed of the mobile station apparatus. Thus, it may be determined whether or not a primary component carrier is allocated to the picocell base station 200c.

  In addition, for example, the cell determination unit 321 is primary to the picocell base station 200c when the mobile station 500c is stationary (or moves at a low speed) and the reception quality of the secondary component carrier is better than a predetermined threshold reception quality. It may be determined whether or not to allocate a component carrier. That is, the cell determination unit 321 may determine whether to assign a primary component carrier to the picocell base station 200c based on the moving speed of the mobile station 500c and the reception quality of the secondary component carrier.

<Fourth Embodiment>
Subsequently, a fourth embodiment will be described. In the third embodiment, the macro cell base station 100c determines that the mobile station 500c is stationary (or moves at a low speed) by detecting the moving speed of the mobile station 500c. The macro cell base station 100d in the fourth embodiment determines that it is stationary (or moves at a low speed) by periodically performing GPS (Global Positioning System) positioning instead of speed detection.

  FIG. 9 is a schematic block diagram illustrating a configuration of a communication system 1d according to the fourth embodiment. Elements common to those in FIG. 2 are denoted by the same reference numerals, and detailed description thereof is omitted. 9 is different from the configuration of the communication system 1 in FIG. 2 in that the mobile station 500 is changed to the mobile station 500d, the macro cell base station 100 is changed to the macro cell base station 100d, and the mobile station 500 is The mobile station is changed to 500d.

  An outline of processing of the communication system 1d according to the fourth embodiment will be described. The core network control device 300 grasps the position of the mobile station 500d by periodically reporting the GPS positioning result from the mobile station 500d. When the core network control device (network control device) 300d determines that the mobile station 500d is staying in the picocell base station 200d, the core network control device (network control device) 300d requests the mobile station 500d to switch the allocation of PCC and SCC. The mobile station 500d performs PCC and SCC allocation switching processing based on the switching request.

The configuration of the mobile station 500d in FIG. 9 is the same as the configuration of the mobile station 500 in FIG. 2 except that the speed detection unit 561 is deleted, the GPS reception unit 581 is added, and the control unit 551 is changed to the control unit 551d. It is a thing. Since the GPS receiving unit 581 performs the same processing as the GPS receiving unit 581 of the second embodiment, the description thereof is omitted.
The control unit 551d transmits the position information input from the GPS reception unit 581 as a GPS positioning result from the P transmission unit 532 to the macro cell base station 100d.

  The configuration of the macro cell base station 100d in FIG. 9 is such that the control unit 131 is changed to a control unit 131d with respect to the configuration of the macro cell base station 100 in FIG. The control unit 131d transmits the GPS positioning result transmitted from the mobile station 500d to the core network control device 300d.

  The configuration of the core network control apparatus 300d in FIG. 9 is obtained by adding a cell determination unit (determination unit) 321d to the configuration of the core network control apparatus 300 in FIG. The cell determination unit 321d has the same function as the cell determination unit 321 of the third embodiment in FIG. 6, but differs in the following points.

The cell determination unit 321d determines whether the mobile station 500d is within the communication range of both the macrocell base station 100 and the picocell base station 200 based on the GPS positioning result transmitted from the macrocell base station 100d. When the mobile station 500d is within the communication range of both the macrocell base station 100 and the picocell base station 200, the cell determination unit 321d calculates the moving speed of the mobile station 500d based on the GPS positioning result transmitted from the macrocell base station 100d. To do. Then, the cell determination unit 321d determines whether to assign a primary component carrier to the picocell base station 200 based on the calculated moving speed.
On the other hand, when the mobile station 500d is not within the communication range of both the macrocell base station 100 and the picocell base station 200, the mobile speed is not calculated and it is not determined whether or not the primary component carrier is allocated to the picocell base station 200.

  FIG. 10 is a sequence diagram illustrating an example of processing of the communication system 1d according to the fourth embodiment. In the sequence of FIG. 1, it is assumed that the mobile station 500d moves from the position P11 of FIG. 1 to the position P12 while allocating the macrocell base station 100d to the PCC and assigning the picocell base station 200 to the SCC and performing CA communication.

  First, at T301, the mobile station 500d communicates with the macrocell base station 100d as a PCC. Next, in T302, in parallel with T301, the mobile station 500d communicates with the picocell base station 200 as SCC. Next, in T303, the mobile station 500d acquires the current position of the mobile station 500d, and transmits a GPS positioning result indicating the acquired current position to the macro cell base station 100d.

Next, in T304, the macro cell base station 100d transmits the GPS positioning result received from the mobile station 500d to the core network control apparatus 300d.
Next, in T305, the cell determination unit 321d of the core network control apparatus 300d calculates the moving speed of the mobile station 500d based on the GPS positioning result received from the macrocell base station 100d. Then, when the calculated moving speed is high, the cell determination unit 321d determines that the PCC and SCC assignment is not switched between the macro cell base station 100d and the pico cell base station 200.

Next, in T306, the mobile station 500d communicates with the macro cell base station 100d as PCC. Next, in T307, in parallel with T306, the mobile station 500d communicates with the picocell base station 200 as SCC.
Next, in T308, the mobile station 500d acquires the current position of the mobile station 500d, and transmits a GPS positioning result indicating the acquired current position to the macro cell base station 100d.
Next, in T309, the macro cell base station 100d transmits the GPS positioning result received from the mobile station 500d to the core network control apparatus 300d.

  Next, in T310, the cell determination unit 321d of the core network control apparatus 300d calculates the moving speed of the mobile station 500d based on the GPS positioning result received from the macrocell base station 100d. Then, when the calculated moving speed is zero, that is, when the mobile station 500d is stationary, the cell determination unit 321d determines to switch the PCC and SCC assignment between the macro cell base station 100d and the pico cell base station 200.

  The processing from T311 to T323 is the same as the processing from T209 to T221 in FIG. Above, the process of this sequence is complete | finished.

<Effect of the fourth embodiment>
As described above, according to the fourth embodiment, the cell determination unit 321d of the core network control apparatus 300d calculates the moving speed of the mobile station 500d based on the GPS positioning result. Then, the cell determination unit 321d determines whether to assign a primary component carrier to the picocell base station 200 based on the calculated moving speed.

  Thereby, since the macro cell base station 100d can distribute the load to the pico cell base station 200, the load on the macro cell base station 100d can be reduced. In addition, the concentration of users on the macro cell base station 100d can be reduced, and the possibility of congestion can be reduced.

  In addition, the conventional macro cell base station has a problem that resource allocation cannot be sufficiently performed because there is a possibility that many users use the macro cell base station having a large cell size. On the other hand, according to this embodiment, the resources of the macro cell base station 100d are opened by assigning the PCC to the pico cell base station 200, so that a large number of users can use the macro cell base station 100d.

  In the fourth embodiment, the cell determination unit 321d determines whether to switch the assignment of PCC and SCC based on the calculated moving speed, but is not limited thereto. In the modification of the fourth embodiment, the cell determination unit 321d may switch the assignment between the PCC and the SCC based on the current position of the mobile station 500d indicated by the GPS positioning result. Specifically, for example, the cell determination unit 321d determines whether or not the current position of the mobile station 500d is within the communication range of the picocell base station 200. Then, if the cell determination unit 321d is within the communication range of the picocell base station 200, the cell determination unit 321d may switch the assignment between the PCC and the SCC, assign the PCC to the picocell base station 200, and assign the SCC to the macrocell base station 100d.

  In view of the text of the fourth embodiment described above and the processing in the modification of the fourth embodiment, the cell determination unit 321d is a mobile station device in the communication range of both the macrocell base station 100d and the picocell base station 200. Based on the information regarding movement, it is determined whether or not the assignment of PCC and SCC is switched between the macrocell base station 100d and the picocell base station 200. Here, the information regarding movement is, for example, the moving speed of the mobile station 500d or the position of the mobile station 500d.

<Modification of each embodiment>
In each of the above embodiments, when each device of the communication system switches between PCC and SCC, a HO (handover) message is used in a HO request, a HO response, or the like. However, the present invention is not limited to this. . In each embodiment, each device of the communication system may be notified by providing another message such as a CC switching request and a CC switching response.

  Further, in each embodiment, each device of the communication system distinguishes between the conventional HO request and the CC switching request used in this modification by adding another parameter for CC switching to the HO message. May be separated. Specifically, in the HO processing of the current standard, when communication is started using another new frequency band, communication previously connected after HO is disconnected. On the other hand, in the present modification, a parameter for the purpose of continuing communication as an SCC may be added without performing the disconnection process of the CC connected as the PCC first. Further, the mobile station may connect to the picocell base station without using the random access request and the random access response.

  In each embodiment, a communication connection has already been established between the mobile station and the macrocell base station, or between the mobile station and the picocell base station, and the mobile station and each base station know the communication timing. Yes. Therefore, in each embodiment, the communication system may switch the allocation of the PCC and the SCC while diverting the timing information before notifying the CC switching request.

In each embodiment, the example in which the communication range of the macro cell base station includes the communication range of the pico cell base station has been described. However, the present invention is not limited thereto, and the communication range of the macro cell base station and the communication range of the pico cell base station are at least one. It suffices if the parts overlap.
In each embodiment, the mobile station or the core network control device has been described as including a macro cell determination unit. However, the present invention is not limited thereto, and the macro cell base station or the pico cell base station may include a macro cell determination unit. That is, any one device included in the communication system 1 only needs to include the macro cell determination unit.

  Further, in each embodiment, from the beginning when the mobile station enters the communication range of the pico cell base station, when the moving speed of the mobile station is slower than a predetermined threshold speed, that is, when moving at low speed, the cell determination unit May determine that the primary component carrier is allocated to the picocell base station. From this, the cell determination unit may determine that the primary component carrier is allocated to the picocell base station based on the information regarding the movement of the mobile station.

  Further, a program for executing each process of the mobile station device or the core network control device of each embodiment is recorded on a computer-readable recording medium, and the program recorded on the recording medium is read into a computer system, By executing, the above-described various processes related to the mobile station apparatus or the core network control apparatus may be performed.

  Here, the “computer system” may include an OS and hardware such as peripheral devices. Further, the “computer system” includes a homepage providing environment (or display environment) if a WWW system is used. The “computer-readable recording medium” means a flexible disk, a magneto-optical disk, a ROM, a writable nonvolatile memory such as a flash memory, a portable medium such as a CD-ROM, a hard disk built in a computer system, etc. This is a storage device.

  Further, the “computer-readable recording medium” refers to a volatile memory (for example, DRAM (Dynamic) in a computer system serving as a server or a client when a program is transmitted via a network such as the Internet or a communication line such as a telephone line. Random Access Memory)) that holds a program for a certain period of time is also included. The program may be transmitted from a computer system storing the program in a storage device or the like to another computer system via a transmission medium or by a transmission wave in the transmission medium. Here, the “transmission medium” for transmitting the program refers to a medium having a function of transmitting information, such as a network (communication network) such as the Internet or a communication line (communication line) such as a telephone line. The program may be for realizing a part of the functions described above. Furthermore, what can implement | achieve the function mentioned above in combination with the program already recorded on the computer system, and what is called a difference file (difference program) may be sufficient.

  As mentioned above, although embodiment of this invention was explained in full detail with reference to drawings, the concrete structure is not restricted to this embodiment, The design etc. of the range which does not deviate from the summary of this invention are included.

1, 1b, 1c, 1d Communication system 100, 100c, 100d Macro cell base station 112 A transmission unit 122 A reception unit 131, 131c, 131d Control unit 100, 100c Pico cell base station 141 Speed detection unit 212 B transmission unit 222 B reception unit 231, 231c Controller 300, 300c, 300d Core network control device (network control device)
311 311c Control unit 321, 321d Cell determination unit (determination unit)
500, 500b Mobile station (mobile station device)
512 P reception unit 522 S reception unit 532 P transmission unit 542 S transmission unit 551, 551b, 551c, 551d Control unit 561 Speed detection unit 571, 571b Cell determination unit (determination unit)
581 GPS receiver

Claims (7)

The moving speed of the mobile station apparatus in the communication range of both the macro cell base station and the pico cell base station having a communication range that overlaps the communication range of the macro cell base station and the communication range narrower than the macro cell base station, and the primary component A determination unit that determines that a primary component carrier is allocated to the picocell base station based on a comparison between a difference in reception quality of a carrier and a reception quality of a secondary component carrier and a threshold that changes according to a moving speed of the own mobile station device ; A mobile station apparatus provided. Before SL determination unit, on the basis of the position of the mobile station apparatus, mobile station apparatus according to the judged claim 1 assigns the primary component carrier to the picocell base station. The difference between the moving speed of the mobile station apparatus in the communication range of both the macro cell base station and the pico cell base station having the communication range overlapping the communication range of the macro cell base station, the reception quality of the primary component carrier, and the reception quality of the secondary component carrier And a determination unit that determines that a primary component carrier is allocated to the picocell base station based on a comparison between the mobile station apparatus and a threshold value that changes according to a moving speed of the mobile station apparatus. Before SL determination unit based on the position of the mobile station apparatus, a network controller according to the determined Claim 3 assign a primary component carrier to the picocell base station. A mobile station device having a communication range that overlaps with a communication range of the macrocell base station and the macrocell base station, and a mobile station device in a communication range of both picocell base stations having a communication range narrower than the macrocell base station, and a primary component carrier A determination unit that determines that a primary component carrier is allocated to the picocell base station based on a comparison between a difference between the reception quality of the mobile station device and a reception quality of the secondary component carrier and a threshold value that changes according to a moving speed of the mobile station device Communications system. The determination unit has a communication range that overlaps with a communication range of the macro cell base station and the macro cell base station, and a moving speed of the mobile station apparatus in the communication range of both the pico cell base stations whose communication range is narrower than the macro cell base station Based on the comparison between the reception quality of the primary component carrier and the reception quality of the secondary component carrier and the threshold value that changes according to the moving speed of the mobile station device, it is determined that the primary component carrier is assigned to the picocell base station. A control method having a procedure. On the computer,
A mobile station device having a communication range that overlaps with a communication range of the macrocell base station and the macrocell base station, and a mobile station device in a communication range of both picocell base stations having a communication range narrower than the macrocell base station, and a primary component carrier A step of determining that a primary component carrier is to be allocated to the picocell base station based on a comparison between a difference between the reception quality of the mobile station device and the reception quality of the secondary component carrier and a threshold value that changes according to a moving speed of the mobile station device Control program for.

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