JP2012204971A - Communication system, controller, and communication method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a communication system which allows a plurality of coordinated base stations to communicate over radio with a mobile station even while the mobile station is moving, a controller therefor, and a communication method therein.SOLUTION: A communication system includes a mobile station, a plurality of base stations capable of communicating over radio with the mobile station, and control means. The control means predicts a location of the mobile station after a predetermined time period of moving and controls radio communication between more than one coordinated base stations and the mobile station on the basis of the predicted location. Preferably, the control means identifies a path of movement of the mobile station and predicts a location after a predetermined time period of moving on the basis of the identified path of movement.

Description

  The present invention relates to a communication system in which a plurality of base stations cooperate to perform wireless communication with a mobile station, a control device directed to the system, and a communication method in the communication system.

  Currently, 3GPP (Third Generation Partnership Project) is promoting standardization of LTE-A (LTE-Advanced) as a new mobile communication technology. LTE-A is a standard developed from LTE (Long Term Evolution).

  In LTE, it is defined that a mobile station communicates with one base station. On the other hand, in LTE-A, it is considered that a plurality of base stations share information and communicate with mobile stations in cooperation. Such a technique is called coordinated multiple point transmission and reception (hereinafter also referred to as “CoMP”).

  LTE-A is expected to improve user throughput and cell throughput at the cell edge as compared to LTE. Therefore, the use of the above-described CoMP for each of the downlink (line) and the uplink (line) has been studied.

  Currently, as a method using CoMP in the downlink, two methods as described below are mainly studied.

  In the first method, as in LTE, a mobile station communicates with a base station on a one-to-one basis, but information is shared by a plurality of adjacent base stations, thereby enabling coordinated scheduling (CS) and coordinated beam. This is a method of reducing interference by cooperatively performing forming (CB: Coordinated Beam forming).

  In the second method, unlike LTE, a plurality of base stations simultaneously transmit signals to one mobile station, and the mobile station combines and demodulates these signals (JP: Joint Processing), This is a method for improving reception quality.

  In any method, in order for a plurality of base stations to communicate with the mobile station in cooperation, information on the state of the communication path with the base station measured by the mobile station (typically, channel quality) Notification CQI (Channel Quality Indicator) is required.

  When the base station determines that it is desirable to perform CoMP, such as when the mobile station is located near the cell edge of the base station, the base station instructs the mobile station to start CoMP Measurement. This CoMP Measurement is a process for collecting information necessary for CoMP implementation, such as CQI, as a stage before CoMP implementation.

  In response to the instruction from the base station, the mobile station starts CoMP Measurement and reports the measurement result obtained as a result to the base station. Based on the measurement result of CoMP Measurement reported from the mobile station, the base station determines whether or not the conditions for performing CoMP are satisfied, and determines that it is desirable to perform CoMP on the mobile station. Then, CoMP is started in cooperation with other base stations.

  Thus, by performing CoMP, the throughput of the mobile station at the cell edge can be improved.

3GPP Organizational Partners, "3rd Generation Partnership Project; Technical Specification Group Radio Access Network; Further Advancements for E-UTRA Physical Layer Aspects (Release 9)", 3GGP TR36.814 v9.0.0 (2010-3), p.17-19 (8.1.3 Feedback in support of DL CoMP)

  In performing CoMP as described above, it is necessary to appropriately grasp the position of the mobile station. For example, when a mobile station is stationary within a cell area, if it is determined that it is desirable to perform CoMP on the mobile station, the corresponding base station sets the directivity of the radio signal to be transmitted as a target. CoMP is started after setting the mobile station. On the other hand, when the mobile station is moving, even if it is determined that it is desirable to perform CoMP on the mobile station, the corresponding base station determines the directivity of the radio signal to be transmitted. It may not be possible to set the target mobile station accurately. In addition, while the base station determines whether it is desirable to perform CoMP on the mobile station, the mobile station may move out of the cell range, and CoMP may not be performed.

  Accordingly, the present invention has been made to solve such a problem, and an object of the present invention is to enable a plurality of base stations to perform radio communication with a mobile station in cooperation with each other even when the mobile station is moving. It is to provide a communication system that can be used, a control device directed to the system, and a communication method in the communication system.

  A communication system according to an aspect of the present invention includes a mobile station, a plurality of base stations capable of wireless communication with the mobile station, and control means. The control means predicts the position of the mobile station after a predetermined period, and controls wireless communication with a mobile station coordinated by two or more base stations based on the predicted position.

  Preferably, the control unit specifies a movement path of the mobile station and predicts a position after a predetermined period based on the specified movement path.

  More preferably, the control unit specifies a moving unit of the mobile station and predicts a position after a predetermined period based on the behavior of the specified moving unit.

  Alternatively, more preferably, the control means determines the moving means of the mobile station based on the moving speed of the mobile station.

  Alternatively, more preferably, the control means determines the mobile means of the mobile station based on information relating to use of the mobile means transmitted from the mobile station.

  Alternatively, more preferably, the control means predicts a position after a predetermined period based on the identified moving path and the moving speed of the mobile station.

  Preferably, the control means predicts a position after a predetermined period based on information from the mobile station.

  Preferably, the control means sequentially selects base stations for performing radio communication with the mobile station in cooperation with one another from among the plurality of base stations according to the position after the predetermined period.

  More preferably, the control means gives a start instruction and an end instruction related to wireless communication with a coordinated mobile station to each of the plurality of base stations at a timing corresponding to a position after a predetermined period.

  A communication system according to another aspect of the present invention includes a mobile station, a plurality of base stations capable of wireless communication with the mobile station, and a control device. The control device predicts the position of the mobile station after a predetermined period, and notifies the predicted positions to a plurality of base stations. The plurality of base stations are based on the positions after the predetermined period notified from the control device. Two or more base stations cooperate to perform wireless communication with a mobile station.

  A communication system according to still another aspect of the present invention includes a mobile station, a plurality of base stations capable of wireless communication with the mobile station, and a control device. The control device identifies a movement path of the mobile station and predicts a position after a predetermined period based on the identified movement path, and the plurality of base stations respond to positions after the predetermined period predicted by the control apparatus. Then, the directivity is adaptively changed to perform wireless communication with the mobile station.

  According to still another aspect of the present invention, a control device adapted to a communication system including a mobile station and a plurality of base stations capable of wireless communication with the mobile station is provided. The control device includes: a means for acquiring the current position of the mobile station; a means for predicting the position of the mobile station after a predetermined period; and a mobile station in which two or more base stations cooperate based on the predicted position. Means for controlling the wireless communication.

  According to still another aspect of the present invention, a communication method in a communication system including a mobile station and a plurality of base stations capable of wireless communication with the mobile station is provided. A communication method includes a step of acquiring a current position of a mobile station, a step of predicting a position of the mobile station after a predetermined period, and a mobile station in which two or more base stations cooperate based on the predicted position. Controlling the wireless communication.

  According to the present invention, even if a mobile station is moving, a plurality of base stations can perform radio communication with the mobile station in cooperation.

It is a figure for demonstrating CoMP operation | movement in LTE-A. It is a figure for demonstrating CoMP operation | movement in LTE-A. It is a figure for demonstrating the process in which the mobile station is moving in the communication system relevant to this Embodiment. It is a schematic diagram which shows the system configuration | structure of the communication system according to embodiment of this invention. It is a block diagram of the mobile station utilized in the communication system according to the embodiment of the present invention. It is a block diagram of the base station utilized in the communication system according to the embodiment of the present invention. It is a block diagram of the control apparatus utilized in the communication system according to the embodiment of the present invention. It is a control block diagram of the whole communication system according to an embodiment of the present invention. It is a figure which shows an example of route map data stored in the database of the control apparatus according to embodiment of this invention. It is a figure which shows an example of the train operation schedule stored in the database of the control apparatus according to embodiment of this invention. It is a figure which shows an example of the cell edge position information stored in the database of the control apparatus according to embodiment of this invention. It is a figure which shows an example of the control map provided by the control apparatus according to embodiment of this invention. It is a sequence diagram which shows the control procedure in the communication system according to embodiment of this invention.

  Embodiments of the present invention will be described in detail with reference to the drawings. Note that the same or corresponding parts in the drawings are denoted by the same reference numerals and description thereof will not be repeated. The present invention is not limited to the embodiments described below, and can be implemented in various modes without departing from the spirit of the present invention.

<A. Related Technology>
First, a communication system related to the present embodiment will be described. 1 and 2 are diagrams for explaining a CoMP operation in LTE-A.

  As shown in FIG. 1 and FIG. 2, the communication system according to the present embodiment and its related communication system include a plurality of base stations 200-1 to 200-3 (hereinafter referred to as “base station 200”) capable of wireless communication with mobile station 100. Are also collectively referred to.). In particular, in any communication system, it is assumed that two or more base stations 200 can perform radio communication with the mobile station 100 in cooperation. As a typical example of a technique in which two or more base stations 200 perform radio communication with the mobile station 100 in cooperation with each other, CoMP under consideration in LTE-A is assumed in the present embodiment. However, in the future, when a new technology is established in which two or more base stations 200 cooperate to perform radio communication with the mobile station 100, the present invention may include such technology within its scope of rights. .

  As described above, in the LTE-A standard currently under consideration, two types of methods are mainly proposed as methods for using CoMP in the downlink.

  In the first method, as in LTE, the mobile station 100 communicates with the base station 200 on a one-to-one basis. However, by sharing information with a plurality of adjacent base stations 200, scheduling and beamforming are coordinated. This is a method of reducing interference.

  For example, consider the case where the mobile station 100 is located at the cell edge between the cell 20-1 and the cell 20-2 as shown in FIG. In this case, the mobile station 100 can receive radio signals from both the base station 200-1 corresponding to the cell 20-1 and the base station 200-2 corresponding to the cell 20-2. Therefore, when receiving a signal from the other base station 200-2 while receiving a signal from one base station 200-1, the received signal becomes an interference source.

  Therefore, in CoMP according to the first method, the base station 200-1 and the base station 200-2 cooperate to control signal transmission timing, radio wave transmission range, and the like, thereby reducing interference with the mobile station 100. .

  The second method is different from LTE in that a plurality of base stations 200 transmit signals simultaneously to one mobile station 100, and the mobile station 100 receives these signals by combining and demodulating them. It is a way to improve quality.

  For example, with reference to FIG. 2, consider the case where the mobile station 100 is located at the cell edge between the cell 20-1 and the cell 20-2 as in FIG. 1. In this case, the mobile station 100 can receive radio signals from both the base station 200-1 corresponding to the cell 20-1 and the base station 200-2 corresponding to the cell 20-2. Therefore, in CoMP according to the second method, the base station 200-1 and the base station 200-2 cooperate with each other to synchronize the signal transmission timing, thereby different data (data 1 and data 1) from the mobile station 100. Send data 2). Thereby, the downlink speed between the mobile station 100 and the base stations 200-1 and 200-2 can be increased.

  Next, problems that may occur in the communication system related to the present embodiment as shown in FIGS. 1 and 2 will be described. FIG. 3 is a diagram for explaining processing during movement of the mobile station 100 in the communication system related to the present embodiment.

  In the communication system shown in FIG. 3, it is assumed that three base stations 200-1 to 200-3 are arranged on both sides of the line RR. It is assumed that the A station and the B station are provided on the track RR, and the train TR operates on the track RR. In the example shown in FIG. 3, it is assumed that the user carrying the mobile station 100 is on the train TR. Therefore, when viewed from the base stations 200-1 to 200-3, the mobile station 100 moves on the line RR.

  In FIG. 3, the communicable ranges (cells 20-1 to 20-3) of the base stations 200-1 to 200-3 are represented as solid circles.

  The operation when CoMP is performed in the situation shown in FIG. 3 will be described. First, a case where the mobile station 100 is located near the A station is set as an initial position. In this initial position, the mobile station 100 is located within the cell 20-1 provided by the base station 200-1. Next, consider that the train TR leaves A station and heads for B station. The B station is located within the cell 20-3 provided by the base station 200-3. A cell 20-2 provided by the base station 200-2 exists between the A station and the B station. Since the cell 20-2 is set to overlap the cell 20-1 and the cell 20-3 at the cell edge, there is a range in which CoMP can be used.

  Consider a case where the mobile station 100 on the train TR reaches a point 401 in the process of the train TR going from the A station to the B station. This point 401 is near the cell edge of the cell 20-2 provided by the base station 200-2. When it is determined that it is desirable for the base station 200-1 to perform the CoMP communication with the movement of the mobile station 100, the base station 200-1 instructs the mobile station 100 to start CoMP Measurement. .

  In response to the instruction from the base station 200-1, the mobile station 100 starts CoMP Measurement and reports the measurement result obtained as a result to the base station 200-1. Based on the measurement result of CoMP Measurement reported from the mobile station 100, the base station 200-1 determines whether or not a preset condition for performing CoMP (CoMP communication implementation condition) is satisfied. . If it is determined that the condition is satisfied, the base station 200-1 cooperates with base stations (in the example illustrated in FIG. 3, the base station 200-2 and / or the base station 200-3) located around the mobile station 100. CoMP communication is started.

  However, when the train TR is moving at a relatively high speed, the time during which the mobile station 100 stays in the vicinity of the cell edge is shortened. For example, after the mobile station 100 reaches the cell edge (point 401), the CoMP Measurement is started, and the base station 200-1 sets the CoMP communication implementation condition based on the measurement result of the CoMP Measurement reported from the mobile station 100. If it is determined whether or not the condition is satisfied, the mobile station 100 moves to a point 403 away from the cell edge before starting CoMP.

  Further, with the event that the mobile station 100 has reached the point 401, the base station 200-1 determines that the CoMP communication implementation condition is satisfied based on the measurement result of CoMP Measurement reported from the mobile station 100, CoMP was started by setting the directivity at point 401 in cooperation with base stations (in the example shown in FIG. 3, base station 200-2 and / or base station 200-3) located around mobile station 100. And However, it is conceivable that the mobile station 100 has already moved to the point 402 at the start of CoMP. In such a case, it becomes difficult to set the directivity of the radio signal transmitted from the base station 200 to the target mobile station 100 accurately.

<B. Summary of the present invention>
In view of the above-described problems, in the communication system according to the present embodiment, the position after a predetermined period of mobile station 100 (hereinafter also referred to as “future position”) is predicted and based on the predicted future position. Then, implement CoMP appropriately.

<C. System configuration>
The communication system according to the present embodiment has a function of predicting the future position as described above. FIG. 4 is a schematic diagram showing a system configuration of the communication system according to the embodiment of the present invention. FIG. 4 shows a configuration of a communication system in which a subject providing a function for predicting the future position as described above is provided separately from the base station 200 as a typical example.

  That is, the communication system according to the present embodiment shown in FIG. 4 includes mobile station 100, a plurality of base stations 200-1 to 200-3 capable of wireless communication with mobile station 100, and control device 300. Base stations 200-1 to 200-3 provide cells 20-1 to 20-3, respectively.

  The control device 300 is configured to exchange various control information with the base stations 200-1 to 200-3. Specifically, the control device 300 is connected to the base stations 200-1 to 200-3 via a wired line such as an optical fiber or a radio signal.

  In the communication system according to the present embodiment, control device 300 predicts the position of mobile station 100 after a predetermined period, and based on the predicted position, mobile station 100 in which two or more base stations 200 cooperate with each other. Control wireless communication with the. That is, the control apparatus 300 gives a control signal to the target base station 200 so that CoMP can be appropriately performed according to the predicted future position of the mobile station 100. In addition, each of the base stations 200 performs radio communication with the mobile station 100 by adaptively changing the directivity according to the future position of the mobile station 100 notified from the control device 300.

  As will be described later, the control apparatus 300 may sequentially select the base station 200 for performing CoMP with the mobile station 100 among the plurality of base stations 200 according to the future position of the mobile station 100. In this case, the control apparatus 300 gives a CoMP start instruction and an end instruction to each of the plurality of base stations 200 at a timing according to the future position of the mobile station 100. Each of the base stations 200 controls the execution of CoMP in accordance with the CoMP start instruction and end instruction from the control device 300.

  Instead of giving a control signal such as a CoMP start / end instruction from the control device 300, each base station 200 may control the implementation of CoMP based on the future position of the mobile station 100. In this case, the control apparatus 300 predicts the position of the mobile station 100 after a predetermined period, and notifies the base station 200 of the predicted position (future position). Each of the base stations 200 performs radio communication with the mobile station 100 in cooperation with each other based on the future position notified from the control device 300.

<D. Configuration of Mobile Station 100>
Next, the configuration of the mobile station used in the communication system according to the embodiment of the present invention will be described. FIG. 5 is a block diagram of mobile station 100 used in the communication system according to the embodiment of the present invention.

  Referring to FIG. 5, mobile station 100 includes a housing 130 provided with a transmission antenna 114 for transmitting a radio signal and a reception antenna 118 for receiving a radio signal. The housing 130 includes a central processing unit 102, a signal processing unit 106, a wireless transmission unit 112, and a wireless reception unit 116.

  The central processing unit 102 includes, as main components, a processor, a nonvolatile memory for holding a program executed by the processor, and a volatile memory functioning as a work memory. The signal processing unit 106 processes a radio signal exchanged with the base station 200 that provides a cell in which the own station exists. More specifically, the signal processing unit 106 outputs information to be transmitted to the base station 200 to the radio transmission unit 112 in accordance with an internal command given from the central processing unit 102 or the like. The wireless transmission unit 112 encodes and modulates the information received from the signal processing unit 106 and radiates a wireless signal obtained as a result to the outside through the transmission antenna 114. Radio receiving section 116 demodulates and decodes the radio signal received through receiving antenna 118, and outputs information obtained as a result to signal processing section 106.

  In particular, since CoMP is performed in the communication system according to the present embodiment, during execution of CoMP, central processing unit 102 and signal processing unit 106 are transmitted from a plurality of base stations 200 in cooperation with each other. Performs processing of combining and demodulating radio signals.

  A part or all of the functions provided by the central processing unit 102 may be implemented as dedicated hardware (integrated circuit). In this case, in addition to the functions provided by the central processing unit 102, one chip including all or part of the functions provided by the signal processing unit 106, the wireless transmission unit 112, and the wireless reception unit 116 May be used. Furthermore, SoC (System On a Chip) in which components such as a processor, a memory, and a controller for peripheral devices are integrated into one chip can be used.

  As an alternative configuration, all or part of the functions provided by the signal processing unit 106, the wireless transmission unit 112, and the wireless reception unit 116 may be implemented as software. In this case, an instruction set in which a computing device (processor) such as a CPU (Central Processing Unit) or DSP (Digital Signal Processor) is installed in advance is executed.

  The casing 130 further includes a display unit 120 for displaying various types of information, a microphone 122 for acquiring user's voice, a speaker 124 for reproducing received voice, and a user operation. It includes an input unit 126 and a GPS (Global Positioning System) unit 128 which is an example of a component for acquiring position information of the own station.

  The mobile station 100 responds to the base station 200 with the current position of the local station acquired by the GPS unit 128 in response to a request from the base station 200 or the like.

<E. Configuration of Base Station 200>
Next, the configuration of base station 200 used in the communication system according to the embodiment of the present invention will be described. FIG. 6 is a block diagram of base station 200 used in the communication system according to the embodiment of the present invention.

  Referring to FIG. 6, base station 200 includes a central processing unit 210, a radio transmission unit 222, a transmission antenna 224, a radio reception unit 226, a reception antenna 228, an upper network interface (I / F) 230, and the like. And a control interface (I / F) 240.

  The central processing unit 210 includes, as main components, a processor, a nonvolatile memory for holding a program executed by the processor, and a volatile memory functioning as a work memory. Further, the central processing unit 210 includes a current position receiving module 202, an instruction receiving module 206, and an instruction execution module 208. These modules are typically provided by the central processing unit 210 executing a program. For example, codes corresponding to each module are stored in advance in a nonvolatile memory, and the central processing unit 210 reads and executes these codes to provide functions as described later.

  The current position receiving module 202 executes processing for receiving the current position from the mobile station 100. Further, the current position reception module 202 may perform processing for requesting the mobile station 100 for the current position.

  The current position transmission module 204 executes processing for transmitting the current position from the mobile station 100 to the control device 300. Identification information may be added to the current position transmitted to the control device 300 so that the corresponding mobile station 100 can be identified.

  The instruction receiving module 206 executes a process for receiving control information from the control device 300. This control information includes a CoMP start instruction / end instruction, a future position of the mobile station 100, directivity information to be set for the mobile station 100, and the like.

  The instruction execution module 208 performs processing according to instructions from the control device 300. More specifically, CoMP is performed while exchanging various types of control information with other base stations 200 according to information regarding the implementation of CoMP from the control device 300. The instruction execution module 208 adaptively changes the directivity of the radio signal radiated from the transmission antenna 224 according to the future position of the mobile station 100 instructed from the control device 300.

  The wireless transmission unit 222 is connected to the transmission antenna 224, generates a wireless signal corresponding to user data or control data received from the central processing unit 210, and radiates the wireless signal from the transmission antenna 224. This user data means data exchanged between the mobile station 100 and the other party (or relay destination).

  The radio reception unit 226 demodulates the radio signal received from the mobile station 100 via the reception antenna 228 into user data or control data, and outputs the demodulated data to the central processing unit 210.

  The host network interface 230 exchanges user data, control information, and management information with a core network device that manages the own station. Similarly, the control interface 240 exchanges control information with the other base stations 200 and the control device 300. In the communication system according to the present embodiment, the base stations 200 are interconnected via a wired line such as an optical fiber or a radio signal in order to implement CoMP.

<F. Configuration of Control Device 300>
Next, the configuration of control device 300 used in the communication system according to the embodiment of the present invention will be described. FIG. 7 is a block diagram of control device 300 used in the communication system according to the embodiment of the present invention.

  Referring to FIG. 7, control device 300 is typically realized based on a general-purpose computer architecture. More specifically, the control device 300 includes a CPU 320, a main memory 322, a database 310, an input interface 332, an output interface 334, and a communication interface 336.

  The CPU 320 is a main body that implements various processes in the control device 300, and sequentially reads and executes codes related to an OS (Operating System) and various module codes developed in the main memory 322.

  The main memory 322 functions as a work memory that holds codes and temporary data for realizing various processes provided by the control device 300. Specifically, the main memory 322 holds a current position reception module 302, a speed calculation module 304, a prediction module 306, and an instruction transmission module 308 read from a secondary memory such as a hard disk. And

  The current position receiving module 302 executes a process for receiving the current position from the mobile station 100 transferred through each base station 200. The speed calculation module 304 executes processing for calculating the moving speed of the mobile station 100 based on the current position from the mobile station 100. The prediction module 306 predicts a position (future position) after a predetermined period of the mobile station 100 based on the moving speed of the mobile station 100 and information stored in the database 310. Further, the prediction module 306 controls that two or more base stations 200 perform wireless communication with the mobile station 100 by CoMP based on the predicted future position. The instruction transmission module 308 performs processing for transmitting control information related to CoMP output by the prediction module 306 to each base station 200.

  The database 310 holds information necessary for future position prediction and CoMP control. For example, as shown in FIG. 3, when there is a track in a cell area, the database 310 holds route map data 312, a train operation schedule 314, cell edge position information 316, and the like.

  The route map data 312 defines position information such as tracks and station buildings. The train operation schedule 314 defines information related to scheduled train operations. For example, the train operation schedule 314 includes a diagram in which time is associated with the position of each train. The cell edge position information 316 defines information about the edge of the cell provided by each base station 200.

  The database 310 is not limited to such a form, and the database 310 specifies information necessary for predicting the future position of the mobile station 100, that is, the movement route and the movement means of the mobile station 100 (the user who carries the mobile station 100). The information of is retained. For example, when there is an expressway or a trunk road in the cell area provided by the base station 200, the database 310 holds information about the road. In this case, the average speed of the vehicle traveling on the road is acquired based on traffic information provided by the traffic information center or the like, traffic jam information (time required between points), and the like. Based on the acquired average speed, it is possible to predict a travel schedule when traveling on a road.

  Although FIG. 7 shows a configuration in which the control device 300 includes the database 310, the database 310 itself does not necessarily have to be mounted. Alternatively, necessary information may be acquired from an external server device through a network.

  The input interface 332 accepts an external instruction and outputs the accepted external input to the CPU 320 or the like. The output interface 334 outputs various information calculated by the CPU 320 to an external device such as a display. The communication interface 336 receives information from the base station 200 and outputs various information calculated by the CPU 320 to the base station 200.

<G. System control action>
Next, overall control operation of the communication system according to the present embodiment will be described. In the following description, it is assumed that three base stations 200-1, 200-2, and 200-3 are arranged on both sides of the line RR as shown in FIG. It is assumed that the A station and the B station are provided on the track RR, and the train TR operates on the track RR. It is assumed that the user carrying the mobile station 100 is on the train TR. Therefore, when viewed from the base stations 200-1 to 200-3, the mobile station 100 moves on the line RR.

  A case where the mobile station 100 is located near the station A is set as an initial position. Therefore, in the initial position, the mobile station 100 exists within the cell 20-1 provided by the base station 200-1.

  FIG. 8 is a control block diagram of the entire communication system according to the embodiment of the present invention. Referring to FIG. 8, mobile station 100 transmits a current position indicating its current position to base station 200 (base station 200-1 in the example illustrated in FIG. 4). The timing for transmitting the current position may be a predetermined period preset for the mobile station 100 or may be scheduled for the mobile station 100 in advance. Further, the base station 200 may request the mobile station 100 to transmit the current position in response to some event.

  In the communication system according to the present embodiment, the positioning result (latitude / longitude) is transmitted using the GPS unit 128 mounted on the mobile station 100, but other methods may be employed. For example, by using the moving unit of the mobile station 100, information on the position from the moving unit may be received, and the information on the position received from the moving unit may be transmitted to the base station 200. For example, a GPS, which is a positioning system, is installed in a train, and a radio signal indicating the current position is broadcast in the train (for example, by a wireless local area network (LAN)). The base station 200 that has received the current position can employ a configuration in which the current position of the train is transmitted to the base station 200 as the current position of the own station.

  Base station 200 (base station 200-1 in the example shown in FIG. 4) starts processing in response to receiving the current position from mobile station 100. That is, the current position receiving module 202 of the base station 200 receives the current position from the mobile station 100. Then, the current position reception module 202 outputs the received current position to the current position transmission module 204. The current position transmission module 204 transmits the received current position of the mobile station 100 to the control device 300.

  The control device 300 starts processing in response to receiving the current position from the mobile station 100 through the base station 200. That is, the current position reception module 302 of the control device 300 receives the current position of the mobile station 100 transmitted from the base station 200. Then, the current position reception module 302 outputs the received current position to the speed calculation module 304 and the prediction module 306.

  The speed calculation module 304 calculates the moving speed of the mobile station 100 based on the current position from each of the mobile stations 100 over a predetermined period. Then, the speed calculation module 304 outputs the moving speed of the mobile station 100 to the prediction module 306.

  The prediction module 306 identifies the movement path of the mobile station 100 by collating information stored in the database 310 based on the current position and movement speed of the mobile station 100, and based on the identified movement path. Thus, the position (future position) of the mobile station 100 after a predetermined period is predicted.

  FIG. 9 shows an example of route map data 312 stored in database 310 of control device 300 according to the embodiment of the present invention. FIG. 10 is a diagram showing an example of a train operation schedule 314 stored in database 310 of control device 300 according to the embodiment of the present invention. FIG. 11 shows an example of cell edge position information 316 stored in database 310 of control apparatus 300 according to the embodiment of the present invention.

  The prediction module 306 of the control device 300 illustrated in FIG. 8 specifies the moving unit of the mobile station 100 based on the current position and the moving speed of the mobile station 100, for example. More specifically, the prediction module 306 refers to the route map data 312 illustrated in FIG. 9 and determines whether there is a point corresponding to the current position of the mobile station 100. That is, the prediction module 306 determines whether the mobile station 100 exists on any train operation route based on the current position of the mobile station 100. FIG. 9 typically shows only an example of route map data 312 corresponding to one route, but when there are a plurality of routes, route map data 312 corresponding to each route is prepared in advance. Is done. When it is determined that the mobile station 100 exists on any train operation route, the prediction module 306 boardes the train on which the user carrying the mobile station 100 operates the route corresponding to the train operation route. Judge that you are doing.

  Furthermore, the prediction module 306 refers to the train operation schedule 314 (diagram) illustrated in FIG. 10 and determines which train the user carrying the mobile station 100 is on. That is, the prediction module 306 specifies coordinates corresponding to the current time and the current position of the mobile station 100 on the diagram, and specifies a train corresponding to the specified coordinates.

  In addition, since the inclination in the diagram shown in FIG. 10 corresponds to the moving speed of the train, a plurality of routes are provided in parallel on the same route, and the trains traveling on each route have different modes of operation. May determine the moving means used by the user carrying the mobile station 100 based on the moving speed of the mobile station 100. Typically, two routes are provided in parallel in the same traveling direction, and one is a slow line and the other is an express line. It can be determined whether a user carrying the mobile station 100 is on a train traveling on the route.

  When it is determined that the mobile station 100 does not exist on any train operation route, the prediction module 306 indicates that the mobile station 100 exists on the route of another moving means (such as a highway or a highway). It may be determined whether or not to do so.

  Through the processing as described above, it is possible to specify the moving means used by the user carrying the mobile station 100 and the behavior of the moving means.

  Subsequently, the prediction module 306 predicts the position (future position) of the mobile station 100 after a predetermined period based on the identified behavior of the moving means. Typically, when the prediction module 306 identifies which train on the diagram shown in FIG. 10 the train used by the user carrying the mobile station 100 is, refer to the diagram. Thus, the future position of the mobile station 100 can be predicted. Further, the prediction module 306 may predict the timing (time) when the mobile station 100 passes the cell edge of each base station 200 by comparing the diagram shown in FIG. 10 with the cell edge position information 316 shown in FIG. it can.

  That is, the cell edge position information 316 shown in FIG. 11 defines the ranges (solid lines) of the cells 20-1 to 20-3 of the base stations 200-1 to 200-3 shown in FIG. 4, and the diagram shown in FIG. The axis in the vertical direction of the drawing defines the line RR shown in FIG. Therefore, by referring to the time corresponding to the intersection of each range of the cells 20-1 to 20-3 and the line RR on the horizontal axis of the diagram shown in FIG. 10, each intersection (cell edge) is determined. The passing timing (time) can be calculated.

  In addition, since the train may not be operated according to the original operation schedule, in such a case, the mobile station is based on the specified train movement path (track) and the moving speed of the mobile station 100. A position after 100 predetermined periods (future position) may be predicted. That is, if the moving means is specified, a route to be moved in the future can be specified. Therefore, a temporal change in the position of the mobile station 100 on the specified moving route can be calculated according to the moving speed of the mobile station 100.

  As described above, the prediction module 306 predicts the position of the mobile station 100 after a predetermined period based on the information from the mobile station 100. Then, the prediction module 306 outputs a prediction result including the future position of the mobile station 100 and the timing (time) of passing through the cell edge to the instruction transmission module 308.

  The instruction transmission module 308 generates information for controlling the implementation of CoMP in the base station 200 based on the prediction result from the prediction module 306. More specifically, the instruction transmission module 308 generates control information including a start instruction and an end instruction related to the implementation of CoMP for each of the base stations 200 at a timing according to the future position of the mobile station 100.

  As an example, the instruction transmission module 308 determines which base station 200 can communicate with the mobile station 100 according to the future position of the mobile station 100. FIG. 12 shows an example of a control map provided by control device 300 according to the embodiment of the present invention.

  The instruction transmission module 308 determines which base station 200 can communicate with the mobile station 100 at each time based on the future position of the mobile station 100. Then, a control map as shown in FIG. 12 is generated. Note that the control map shown in FIG. 12 is for convenience of explanation, and the data structure actually mounted is not limited to the format shown in FIG.

  As illustrated in FIG. 12, the base station 200 that provides a cell that covers each future position is specified based on the future position of the mobile station 100 at each of the times t1 to t6. In the control map shown in FIG. 12, “Y” indicates that the corresponding base station 200 can communicate with the mobile station 100, and “N” indicates that the corresponding base station 200 cannot communicate with the mobile station 100. It shows that. Then, the instruction transmission module 308 changes the timing at which the mobile station 100 passes the cell edge in the control map shown in FIG. 12, that is, the state of one of the base stations 200 changes from “Y” to “N” or “ The time when “N” is changed to “Y” is specified. Then, the instruction transmission module 308 generates a start instruction for instructing the execution of CoMP and / or an end instruction for instructing the end of CoMP at a timing according to the passage time of the cell edge of the mobile station 100 and the like.

  That is, when the instruction transmission module 308 of the control device 300 determines that it is desirable to perform CoMP on the mobile station 100 based on the predicted passing time of the cell edge of the mobile station 100, the mobile station 100 A CoMP start instruction is transmitted to 100 peripheral base stations (in the example shown in FIG. 4, base stations 200-1 to 200-3). On the other hand, if it is determined that it is desirable to end CoMP on the mobile station 100 based on the predicted passage time of the cell edge of the mobile station 100, the neighboring base stations of the mobile station 100 (shown in FIG. 4). In the example, a CoMP end instruction is transmitted to the base stations 200-1 to 200-3).

  Further, the instruction transmission module 308 transmits the future position of the mobile station 100 to the corresponding base station 200 when transmitting the CoMP start instruction and / or the CoMP end instruction.

  Referring to FIG. 8 again, the instruction receiving module 206 of the base station 200 executes a process for receiving control information (the future position of the mobile station 100, and the CoMP start instruction and end instruction) from the control device 300. To do. The instruction receiving module 206 outputs the received control information to the instruction execution module 208.

  The instruction execution module 208 performs control related to CoMP according to control information from the control device 300. More specifically, when receiving a CoMP start instruction from the control device 300, the instruction execution module 208 exchanges control information with other base stations 200 and performs CoMP on the mobile station 100. At this time, the directivity of the radio signal transmitted by the base station 200 is adaptively changed to the target mobile station 100 in accordance with the future position of the mobile station 100 notified from the control device 300. On the other hand, when receiving the CoMP end instruction from the control device 300, the instruction execution module 208 ends the CoMP being executed.

  Note that the CoMP start instruction and the CoMP end instruction from the control apparatus 300 may be notified to the base station 200 in advance. In this case, the time to start CoMP is added to the CoMP start instruction, and the time to end CoMP is added to the CoMP end instruction. Then, when the time notified in advance arrives, each base station 200 performs CoMP or ends CoMP according to the instruction.

<H. Processing procedure>
Next, the processing procedure in the communication system according to the present embodiment as described above can be summarized as follows. FIG. 13 is a sequence diagram showing a control procedure in the communication system according to the embodiment of the present invention.

  Referring to FIG. 13, first, mobile station 100 acquires the current position using built-in GPS unit 128 or the like when a predetermined transmission cycle arrives (sequence SQ100). Then, mobile station 100 transmits the acquired current position to base station 200 (base station 200-1 in the example of FIG. 13) that provides the cell to which the mobile station belongs (sequence SQ102). Subsequently, base station 200-1 that has received the current position from mobile station 100 transmits the received current position to control device 300 (sequence SQ104).

  When control apparatus 300 acquires the current position from mobile station 100 via base station 200-1, control apparatus 300 calculates the moving speed of mobile station 100 (sequence SQ106). Normally, the moving speed of the mobile station 100 is calculated using a plurality of current positions acquired from the same mobile station 100 at different times.

  Subsequently, control device 300 specifies the moving means used by the user carrying mobile station 100 (sequence SQ108). For specifying the moving means, as described above, the current position and moving speed of the mobile station 100 are used. Subsequently, control device 300 calculates the position (future position) of mobile station 100 after a predetermined period based on the moving means specified in sequence SQ108 and the moving path related to the moving means (sequence SQ110). Furthermore, control apparatus 300 predicts the timing at which mobile station 100 passes the cell edge of the cell provided by each base station 200 (sequence SQ112). Finally, control apparatus 300 schedules CoMP performed by base station 200 for mobile station 100 based on the timing predicted in sequence SQ112 (sequence SQ114).

  Based on the schedule determined in sequence SQ114, control device 300 determines whether or not the timing for starting the implementation of CoMP has arrived for mobile station 100 (sequence SQ116). When the timing for starting the implementation of CoMP has arrived (YES in sequence SQ116), control device 300 provides base station 200-1 to 200-3 with a CoMP start instruction and a future position of mobile station 100. Transmit (sequence SQ118).

  In accordance with the CoMP start instruction, base stations 200-1 to 200-3 start performing CoMP on mobile station 100 (sequence SQ120). At this time, base stations 200-1 to 200-3 perform radio communication with mobile station 100 while adaptively changing the directivity according to the future position of mobile station 100 notified from control device 300.

  During the execution of CoMP, control device 300 determines whether or not the timing for ending the execution of CoMP has arrived for mobile station 100 based on the schedule determined in sequence SQ114 (sequence SQ122). When it is time to end CoMP implementation (YES in sequence SQ122), control device 300 transmits a CoMP end instruction to base stations 200-1 to 200-3 (sequence SQ124).

  In accordance with the CoMP termination instruction, base stations 200-1 to 200-3 terminate CoMP for mobile station 100 (sequence SQ126). Then, the normal communication mode is restored.

<I. Modification 1>
In the above-described embodiment, the configuration in which the moving means used by the user carrying the mobile station 100 is specified based on the current position and moving speed of the mobile station 100 has been described. However, the user uses the moving means. It is also possible to specify the moving means using information linked to the.

  In other words, the mobile station 100 may transmit information on the use of the mobile means to the control device 300 and determine the mobile means of the mobile station 100 based on this information. For example, a radio signal indicating that it exists in a train is broadcast in the train (for example, by a wireless local area network (LAN)), and the mobile station 100 that receives this radio signal A configuration in which it is determined that the vehicle is present in the train and the information is transmitted to the base station 200 can be adopted.

  Alternatively, when the mobile station 100 is equipped with an additional function (typically, a payment function for using a transportation facility) for using the moving means, the payment function is used. In response, the base station 200 may be notified of the transportation facility to be used.

<J. Modification 2>
In the above-described embodiment, the configuration in which the control device 300 is provided as another execution subject in addition to the mobile station 100 and the base station 200 has been illustrated, but the functions provided by the control device 300 are provided in the base station 200. You may arrange | position and distribute. In this case, modules provided by the control device 300 shown in FIGS. 7 and 8 are allocated to the base station 200.

  Further, only a part of the functions provided by the control device 300 may be assigned to the base station 200. For example, the speed calculation module 304 of the control device 300 may be moved to the base station 200. In this case, the base station 200 that provides the cell in which the mobile station 100 exists calculates the moving speed of the mobile station 100 and transmits it to the control device 300 together with the current position of the mobile station 100. By adopting such a configuration, the processing load on the control device 300 can be reduced.

  Further, regarding the moving speed of the mobile station 100, the mobile station 100 itself may calculate the moving speed and transmit it to the base station 200 together with the current position of the own station.

<K. Effect>
According to the present embodiment, in an environment in which a moving means such as a train and its moving route can be specified, the control device can control the future of the mobile station so that a plurality of base stations can perform CoMP on the moving mobile station. Predict location etc. Then, CoMP is adaptively performed by predicting the time when the mobile station passes the cell edge of the cell provided by the base station.

  Thus, CoMP can be started without acquiring the measurement result of CoMP Measurement and the like by predicting the future position of the mobile station and the time when the mobile station passes the cell edge. Therefore, the processing load between the mobile station and the base station can be reduced. Furthermore, the start of CoMP for a moving mobile station can be determined at an earlier timing. Therefore, it is possible to provide CoMP communication over a longer period.

  Also, by predicting the future position of the mobile station, CoMP communication can be performed by adaptively changing the directivity for the moving mobile station, so that the throughput can be further increased.

  According to the current CoMP standard, there may occur a situation where the mobile station moves out of the cell range before the determination as to whether or not to start CoMP is completed for a mobile station moving at a relatively high speed. In the communication system according to the present embodiment, such a situation can be avoided and CoMP can be stably performed.

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

  20-1 to 20-3 cell, 100 mobile station, 102, 210 central processing unit, 106 signal processing unit, 112, 222 radio transmission unit, 114, 224 transmission antenna, 116, 226 radio reception unit, 118, 228 reception antenna , 120 display unit, 122 microphone, 124 speaker, 126 input unit, 128 unit, 130 housing, 200, 200-1 to 200-3 base station, 202, 302 current position receiving module, 204 current position transmitting module, 206 instruction Reception module, 208 instruction execution module, 230 upper network interface, 240 control interface, 300 control device, 304 speed calculation module, 306 prediction module, 308 instruction transmission module, 310 database, 312 route map data 314 train operation schedule, 316 cell edge position information, 320 CPU, 322 main memory, 332 input interface, 334 output interface, 336 communication interface, RR line, TR train.

Claims (13)

A mobile station,
A plurality of base stations capable of wireless communication with the mobile station;
Control means,
The control means predicts the position of the mobile station after a predetermined period, and controls wireless communication between the mobile stations coordinated by two or more base stations based on the predicted position. Communications system.   The communication system according to claim 1, wherein the control unit specifies a movement path of the mobile station and predicts a position after the predetermined period based on the specified movement path.   The communication system according to claim 2, wherein the control unit specifies a moving unit of the mobile station and predicts a position after the predetermined period based on a behavior of the specified moving unit.   The communication system according to claim 3, wherein the control unit determines a moving unit of the mobile station based on a moving speed of the mobile station.   The communication system according to claim 3, wherein the control unit determines the mobile unit of the mobile station based on information on the use of the mobile unit transmitted from the mobile station.   The communication system according to claim 3, wherein the control unit predicts a position after the predetermined period based on the identified moving path and a moving speed of the mobile station.   The communication system according to claim 1, wherein the control unit predicts a position after the predetermined period based on information from the mobile station.   The control unit according to any one of claims 1 to 7, wherein the control means sequentially selects a base station for performing radio communication with a mobile station in a coordinated manner among the plurality of base stations according to a position after the predetermined period. The communication system according to item.   The control means gives a start instruction and an end instruction related to wireless communication with the coordinated mobile station to each of the plurality of base stations at a timing according to a position after the predetermined period. 9. The communication system according to 8. A mobile station,
A plurality of base stations capable of wireless communication with the mobile station;
A control device,
The control device predicts the position of the mobile station after a predetermined period, notifies the predicted position to the plurality of base stations,
The communication system in which the plurality of base stations perform wireless communication with the mobile station in cooperation of two or more of the base stations based on the position after the predetermined period notified from the control device. A mobile station,
A plurality of base stations capable of wireless communication with the mobile station;
A control device,
The control device specifies a movement path of the mobile station, predicts a position after a predetermined period based on the specified movement path,
The communication system in which the plurality of base stations perform radio communication with the mobile station by adaptively changing directivity according to a position after the predetermined period predicted by the control device. A control device adapted to a communication system including a mobile station and a plurality of base stations capable of wireless communication with the mobile station,
Means for obtaining a current position of the mobile station;
Means for predicting the position of the mobile station after a predetermined period;
A control device comprising: means for controlling wireless communication between the mobile stations coordinated by two or more of the base stations based on the predicted position. A communication method in a communication system including a mobile station and a plurality of base stations capable of wireless communication with the mobile station,
Obtaining a current position of the mobile station;
Predicting the position of the mobile station after a predetermined period;
And a step of controlling wireless communication between the mobile stations coordinated by two or more of the base stations based on the predicted position.

Images