JP2019102951A - Terminal device, base station selection method, and computer program - Google Patents

Abstract

To connect to a base station where radio communication is more stable for a terminal among a plurality of base stations.SOLUTION: The terminal device is configured to: measure radio quality for each beam transmitted from a base station device (S1); calculate the number of connectable beams that satisfy predetermined wireless quality for each base station device and generate a base station selection index indicating a degree of the number of connectable beams for each base station device (S2); and establish a wireless communication connection with a base station device selected as a connection destination of the own terminal device from among a plurality of base station devices on the basis of the base station selection index (S4).SELECTED DRAWING: Figure 4

Description

  The present invention relates to a terminal device, a base station selection method and a computer program.

  In recent years, base station selection techniques for selecting a base station to which a terminal is connected from among a plurality of base stations in a radio communication system using a millimeter wave band have been studied (see, for example, non-patent documents 1 and 2). In the prior art of Non-Patent Document 1, a base station with which the received SNR of the beam is a maximum value is selected. In the prior art of Non-Patent Document 2, a base station having the maximum received RSSI of a beam is selected.

M. Polese, et al., “Improved Handover Through Dual Connectivity in 5 G mm Mobile Networks”, IEEE Journal on Selected Areas 2017.9. Mohammed Saquib Khan, et al., "Cell Selection Technique for Millimeter-Wave Cellular Systems with Hybrid Beamforming", Sensors 17-01461 2017.

  However, in the above-described conventional base station selection technology, there is a case in which a base station having a problem in the stability of wireless communication is selected from the plurality of base stations.

  FIG. 8 is an explanatory view of a wireless environment in a railway car (a passenger car). FIG. 9 is an explanatory view of a conventional base station selection technique in the railway car shown in FIG. In FIG. 8 and FIG. 9, two base stations (BSID1, BSID2) provided on the ceiling in the railway vehicle are shown. In addition, a passenger sits in a seat and uses a terminal. One base station (BSID1) is located farther from the terminal than the other base station (BSID2). Therefore, the base station (BSID2) is closer to the terminal than the base station (BSID1).

  A millimeter wave band radio wave (hereinafter referred to as a millimeter wave) has a propagation characteristic that is easily blocked by the human body. For this reason, in the railway vehicle, the propagation path of the millimeter wave is blocked by the person on the passage. In the example of FIG. 8, in the millimeter wave propagation path between the terminal and the base station (BSID1), the time for a person on the path to pass through between the terminal and the base station (BSID1) is from the terminal and the base station (BSID2) Because it is also long, the time to be blocked is longer than between the terminal-base station (BSID 2). On the other hand, in the millimeter wave propagation path between the terminal and the base station (BSID2), the time for a person on the path to pass through between the terminal and the base station (BSID2) is longer than that between the terminal and the base station (BSID1). Because it is short, the time to be blocked is shorter than between the terminal-base station (BSID 1).

  In addition, millimeter waves are highly rectilinear and have propagation characteristics of being reflected by a reflector such as a wall. For this reason, as the millimeter wave propagation characteristics in the railway vehicle, the occurrence of multiple reflections of millimeter waves causes the propagation loss of the millimeter waves to greatly fluctuate and the propagation loss of the millimeter waves becomes smaller than that in free space. Have. In the example of FIG. 9, the terminal receives the peak of the variation in the intensity of the millimeter wave from the base station (BSID1) present at a position far from the terminal, while the base station (BSID2) present at a position near the terminal. In the wireless environment to receive the bottom of millimeter wave fluctuations from. Therefore, in the terminal, since the propagation loss between the terminal and the base station (BSID1) is smaller than the propagation loss between the terminal and the base station (BSID2), the received RSSI from the base station (BSID1) is the base station (BSID2) Greater than the received RSSI. In this case, in the conventional base station selection technology, the “base station (BSID1) present at a place far from the terminal” with the larger received RSSI is selected as the base station to which the terminal is connected. However, the base station (BSID1) selected as the base station to which the terminal is connected is a base station whose radio communication stability is worse for the terminal than the base station (BSID2) present in the vicinity of the terminal .

  The present invention has been made in consideration of such circumstances, and an object thereof is to connect to a base station where radio communication is more stable for a terminal among a plurality of base stations.

(1) One aspect of the present invention is a base station search unit for measuring radio quality for each beam transmitted from the base station apparatus in the terminal apparatus of a wireless communication system including the terminal apparatus and a plurality of base station apparatuses And calculating the number of connectable beams satisfying predetermined wireless quality with respect to each of the base station devices, and generating a base station selection index indicating the degree of the number of connectable beams for each of the base station devices. Communication for establishing wireless connection to a base station apparatus selected as a connection destination of the own terminal apparatus from among the plurality of base station apparatuses based on the base station selection index generating unit and the base station selection index And a control unit.
(2) In one aspect of the present invention, in the terminal device of the above (1), based on the base station selection index, select a base station device to be connected to the own terminal device from among the plurality of base station devices. And a base station selection unit.
(3) In one embodiment of the present invention, in the terminal device according to the above (2), the base station selection unit evaluates measurement results of radio quality in a predetermined period with respect to each base station device, and The terminal apparatus selects a base station apparatus whose result satisfies a predetermined base station priority condition as a connection destination of its own terminal apparatus in preference to a selection result of a base station apparatus based on the base station selection index.
(4) In one aspect of the present invention, in the terminal device according to any one of (1) to (3), a notification unit for transmitting the base station selection index to the base station device connected to the own terminal device. It is a terminal unit further provided.

(5) One aspect of the present invention is a base station selection method of a wireless communication system including a terminal apparatus and a plurality of base station apparatuses, wherein the terminal apparatus wirelessly transmits each beam transmitted from the base station apparatus. In the base station search step of measuring the quality, the terminal device calculates the number of connectable beams satisfying predetermined radio quality for each base station device, and the degree of the number of connectable beams is calculated. A base station selection index generation step of generating a base station selection index representing each of the base station apparatuses, and the terminal apparatus is connected to the own terminal apparatus among the plurality of base station apparatuses based on the base station selection index. And a communication control step of wirelessly connecting to the selected base station apparatus.

(6) One aspect of the present invention is a base station that measures radio quality for each beam transmitted from the base station apparatus to a computer of the terminal apparatus of a wireless communication system including the terminal apparatus and a plurality of base station apparatuses A search function and the number of connectable beams satisfying predetermined radio quality for each base station device is calculated, and a base station selection index indicating the degree of the number of connectable beams for each base station device The wireless communication connection is established wirelessly to the base station apparatus selected as the connection destination of the own terminal apparatus from among the plurality of base station apparatuses based on the base station selection index generating function to be generated and the base station selection index. A computer program for realizing a communication control function to be performed.

  According to the present invention, it is possible to obtain an effect that it is possible to establish connection from a plurality of base stations to a base station where radio communication is more stable for the terminal.

It is a schematic block diagram of the radio | wireless communications system which concerns on one Embodiment. It is a block diagram showing an example of outline composition of terminal unit 10 concerning one embodiment. It is a block diagram which shows the example of a schematic structure of the base station apparatus 30 which concerns on one Embodiment. 5 is a schematic flowchart of a base station selection method according to an embodiment. It is a sequence chart of operation | movement of the radio | wireless communications system 1 which concerns on one Embodiment. It is a figure which shows the example of the group of base station ID and the number of connectable beams which concern on one Embodiment. It is a graph which shows the relationship between the number of connectable beams which concern on one Embodiment, and a base station-seat distance. It is explanatory drawing of the radio | wireless environment in the rail car (passenger car). It is explanatory drawing of the conventional base station selection technique.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a schematic configuration diagram of a wireless communication system according to an embodiment. In FIG. 1, the wireless communication system 1 includes a terminal device 10 and a plurality of base station devices 30-1, ..., 30-N. N is an integer of 2 or more. The wireless communication system 1 is provided, for example, in a rail car (a passenger car) as shown in FIG. A plurality of base station apparatuses 30-1, ..., 30-N (hereinafter referred to as "base station apparatus 30" when not particularly distinguished) in a rail car (guest car) are, for example, as shown in FIG. Installed on the ceiling in the railway car. In addition, the terminal device 10 is used by a passenger sitting in a seat, for example, in a railway vehicle as shown in FIG.

  The base station apparatus 30 can transmit a plurality of beams having directivity. The terminal device 10 wirelessly connects to the base station device 30 to perform communication. In the present embodiment, a millimeter wave will be described as an example of radio waves used by the wireless communication system 1 for wireless communication.

  FIG. 2 is a block diagram showing a schematic configuration example of the terminal device 10 according to the present embodiment. In FIG. 2, the terminal device 10 includes a radio unit 11, a base station search unit 12, a base station selection index generation unit 13, a communication control unit 14, a base station selection unit 15, and a storage unit 16. . The wireless unit 11 transmits and receives wireless signals via an antenna (not shown) of the terminal device 10. The base station search unit 12 measures radio quality for each beam transmitted from the base station apparatus 30.

  The base station selection index generation unit 13 calculates the number of connectable beams satisfying predetermined radio quality for each base station apparatus 30, and base station selection index indicating the degree of the number of connectable beams. It is generated for each station device 30. The connectable beam is a beam that the base station device 30 transmits, and is a beam that the terminal device 10 can connect to the base station device 30 by radio. The connectable beam satisfying the predetermined wireless quality is a connectable beam transmitted by the base station apparatus 30, and the terminal apparatus 10 satisfies the predetermined wireless quality in the wireless communication with the base station apparatus 30. It can be connected beam. As radio quality, received signal strength indicator (RSSI), signal to interference noise power ratio (SINR), carrier to interference and noise power ratio (CINR): carrier to interference wave and noise power Ratio etc. may be applied. The predetermined radio quality is, for example, an RSSI threshold at which one beam can provide a predetermined throughput (eg, 1 gigabit per second) or more.

  The base station selection index is information indicating the degree of the number of connectable beams. The base station selection index may be the number of connectable beams, or a level representing the number of connectable beams in stages (for example, three levels of "many", "medium" and "little", or , Level 1 to level 10, etc.).

  The communication control unit 14 controls wireless communication of the terminal device 10. The communication control unit 14 wirelessly connects communication to the base station device 30 selected as the connection destination of the own terminal device 10 from among the plurality of base station devices 30 based on the base station selection index. The base station selection unit 15 selects, from among the plurality of base station apparatuses 30, the base station apparatus 30 to which the terminal apparatus 10 is to be connected based on the base station selection index. The storage unit 16 stores data.

  As the terminal device 10, a mobile communication terminal device such as a smartphone or a tablet computer (tablet PC) may be applied.

  FIG. 3 is a block diagram showing a schematic configuration example of the base station apparatus 30 according to the present embodiment. In FIG. 3, the base station apparatus 30 includes a radio unit 31 and a beam control unit 32. The wireless unit 31 transmits and receives wireless signals via an antenna (not shown) of the base station device 30. The beam control unit 32 controls the beam transmitted from the antenna of the base station device 30.

  Next, the base station selection method according to the present embodiment will be described with reference to FIGS. 4 and 5. FIG. 4 is a schematic flowchart of a base station selection method according to the present embodiment. FIG. 5 is a sequence chart of the operation of the wireless communication system 1 according to the present embodiment.

(Step S1) The base station search unit 12 of the terminal device 10 targets each of the N base station devices 30-1, ..., 30-N for each beam transmitted from the base station device 30. Measure wireless quality. Step S1 will be described in detail with reference to FIG. The base station search unit 12 of the terminal device 10 sequentially executes step S1-1 to step S1-3 of step S1 on the N base station devices 30-1, ..., 30-N.

(Step S1-1) The base station search unit 12 of the terminal device 10 requests the base station device 30 to transmit all beams.

(Step S1-2) The beam control unit 32 of the base station device 30 controls beam transmission so as to transmit all the beams sequentially or all at once, in response to a request from the terminal device 10. Thereby, the base station apparatus 30 transmits all beams sequentially or all at once. The beam transmitted from the base station device 30 is a beam having a radio signal such as a reference signal or a beacon including a base station identifier (base station ID) and a beam identifier (beam ID). This makes it possible to identify which beam transmitted from which base station apparatus 30 a certain beam is.

(Step S1-3) The base station search unit 12 of the terminal device 10 receives beams sequentially or all at once. The base station search unit 12 acquires a base station ID and a beam ID from each of the received beams. Also, the base station search unit 12 measures the radio quality of each received beam. Here, the RSSI (received RSSI) of the received beam is measured as an example of the radio quality measurement item. The base station search unit 12 writes sets of the base station ID, the beam ID, and the received RSSI in the storage unit 16 for each of the received beams. Thereby, the storage unit 16 stores a set of a base station ID, a beam ID, and a received RSSI for each beam received by the base station search unit 12.

  The base station search unit 12 of the terminal device 10 may specify, as a beam transmission method, whether to transmit all beams sequentially or transmit all beams simultaneously to the base station device 30. The beam control unit 32 of the base station device 30 controls the transmission of beams so as to transmit all beams by the beam transmission method specified by the terminal device 10.

The explanation is returned to FIG.
(Step S2) The base station selection index generation unit 13 of the terminal device 10 calculates the number of connectable beams that satisfy a predetermined RSSI threshold for each base station device 30, and the degree of the number of connectable beams A base station selection index representing H is generated for each base station apparatus 30. Here, the number of connectable beams is generated as an example of the base station selection index. Step S2 will be described in detail with reference to FIG.

(Step S2-1) The base station selection index generation unit 13 of the terminal device 10 sequentially reads out the set of the base station ID, the beam ID, and the reception RSSI from the storage unit 16.

(Step S2-2) The base station selection index generation unit 13 of the terminal device 10 searches for a beam ID of a set whose received RSSI is equal to or greater than the RSSI threshold, and sets the number of searched beam IDs (the number of connectable beams) as a base. Counts each station ID. Thereby, the number of beams (the number of connectable beams) having the received RSSI equal to or greater than the RSSI threshold among all beams transmitted from the same base station apparatus 30 is calculated. The base station selection index generation unit 13 writes the set of the base station ID and the number of connectable beams in the storage unit 16. Thereby, the storage unit 16 stores a set of the base station ID and the connectable beam number for each base station apparatus 30, as illustrated in FIG. The example of FIG. 6 is the case where the number N of base station apparatuses 30 is four.

The explanation is returned to FIG.
(Step S3) The base station selection unit 15 of the terminal device 10 selects the connection destination of the own terminal device 10 from among the N base station devices 30-1, ..., 30-N based on the number of connectable beams. The base station apparatus 30 to be used is selected. Here, as an example of the base station selection method, the base station apparatus 30 having the largest number of connectable beams is selected as the base station apparatus 30 to which the terminal apparatus 10 is to be connected. Step S3 will be described in detail with reference to FIG.

(Step S3-1) The base station selection unit 15 of the terminal device 10 sequentially reads out a set of the base station ID and the number of connectable beams from the storage unit 16. The base station selection unit 15 searches for the maximum value of the connectable beam number, and acquires the set of base station IDs to which the searched maximum connectable beam number belongs. The base station selection unit 15 selects the base station apparatus 30 of the acquired base station ID as the base station apparatus 30 to which the terminal apparatus 10 is to be connected. In the example of FIG. 6, the base station apparatus 30 with the base station ID "BSID2" of the group to which the largest connectable beam number "10" belongs is selected as the base station apparatus 30 to which the terminal apparatus 10 is connected.

(Step S3-2) The base station selection unit 15 of the terminal device 10 stores the base station ID of the selected base station device 30 as the base station ID of the base station device 30 to which the terminal device 10 is connected. Write to section 16 Thereby, the storage unit 16 stores the base station ID of the base station apparatus 30 to which the terminal apparatus 10 is connected.

The explanation is returned to FIG.
(Step S4) The communication control unit 14 of the terminal device 10 wirelessly connects communication to the base station device 30 selected as the connection destination of the own terminal device 10. Specifically, the communication control unit 14 reads from the storage unit 16 the base station ID of the base station apparatus 30 to which the terminal apparatus 10 is to be connected. The communication control unit 14 wirelessly transmits a connection request to the base station apparatus 30 of the base station ID using the read out base station ID. As a result, communication connection is established wirelessly between the terminal device 10 and the base station device 30 of the base station ID.

  According to the present embodiment, the base station search unit 12 measures the radio quality for each beam transmitted from the plurality of base station apparatuses 30, and the base station selection index generation unit 13 generates a predetermined value for each base station apparatus 30. The number of connectable beams satisfying wireless quality is calculated, and a base station selection index indicating the degree of the number of connectable beams is generated for each base station apparatus 30, and the communication control unit 14 is based on the base station selection index. Communication is wirelessly connected to the base station device 30 selected from among the plurality of base station devices 30 as the connection destination of the own terminal device 10. Thus, the terminal device 10 can wirelessly connect to the base station device 30 having a large number of connectable beams (for example, the maximum number of connectable beams). The effect that the terminal device 10 can be connected to the base station device 30 with more stable wireless communication can be obtained.

  Further, the base station apparatus 30 further includes the base station selection unit 15 and the base station selection unit 15 selects one of the plurality of base station apparatuses 30 as the connection destination of the own terminal apparatus 10 based on the base station selection index. May be selected. As a result, the terminal apparatus 10 can select the base station apparatus 30 to be connected to itself by itself.

  The present embodiment is based on the technical idea that the base station apparatus 30 having a larger number of connectable beams is a more stable wireless communication for the terminal apparatus 10. When the wireless communication system 1 performs wireless communication using millimeter waves, as illustrated in FIG. 8, the base station apparatus 30 to which the terminal apparatus 10 is connected is provided in a railway vehicle (guest car) as illustrated in FIG. The base station apparatus 30 which exists relatively near to the said terminal device 10 is preferable at the point of stability of radio | wireless communication. The effect by this embodiment in this point is explained with reference to FIG.

  The graph shown in FIG. 7 shows the relationship between the number of connectable beams and the distance between the base station and the seat in a railcar (a passenger car) as exemplified in FIG. The graph of FIG. 7 is created from the result of simulation using a ray tracing method. In the example of FIG. 7, the base station is installed on the ceiling of the eighth row of seats in the passenger car. The terminal is used by a passenger seated in a seat.

  As shown in the graph of FIG. 7, the number of connectable beams decreases as the seat is farther from the base station. Therefore, there is a relation that the distance between the seat (terminal) and the base station is shorter as the number of connectable beams is larger. Thus, when the wireless communication system 1 performs wireless communication using millimeter waves, as illustrated in FIG. 8, the base station device to which the terminal device 10 is connected when provided in a rail car (guest car) as illustrated in FIG. It is preferable to select the base station apparatus 30 having a large number of connectable beams as the point 30 in terms of the stability of wireless communication. Therefore, according to the present embodiment, even when the wireless communication system 1 performs wireless communication using millimeter waves, even when the wireless communication system 1 is provided in a railway vehicle (a passenger car) as illustrated in FIG. The effect of being able to connect to the base station apparatus 30 which makes the radio communication more stable for the terminal apparatus 10 from among the plurality of base station apparatuses 30 can be obtained.

  Next, a modification of the present embodiment will be described.

(Modification 1)
In the above embodiment, as an example of the base station selection method, the base station apparatus 30 having the largest number of connectable beams is selected as the base station apparatus 30 to which the terminal apparatus 10 is connected, but other base station selection methods It may be For example, any base station apparatus 30 may be selected from among the base station apparatuses 30 whose number of connectable beams is a predetermined number or more. Alternatively, the base station apparatus 30 that satisfies the predetermined base station selection condition A may be selected from among the base station apparatuses 30 in which the number of connectable beams is a predetermined number or more. The base station selection condition A may be, for example, a threshold of the radio quality of the beam. The radio quality of the beam may be, for example, a statistical value (for example, an average value or the like) calculated from the radio quality of all the beams of the base station apparatus 30, or the radio quality of all the beams of the base station apparatus 30 The maximum value, the minimum value, or the intermediate value in Alternatively, the base station selection condition A may be, for example, that the terminal connection number threshold has not been reached. In this case, the current number of terminal connections of each base station apparatus 30 may be notified to the terminal apparatus 10, for example, by being included in the radio signal of the beam transmitted from each base station apparatus 30 and transmitted. .

(Modification 2)
A base station priority condition B different from the base station selection index may be used together. For example, a radio quality different from the base station selection index, a different statistical value (for example, the average time is longer than the base station selection index, etc.) is set as the base station priority condition B. The base station selection unit 15 evaluates the measurement results of the radio quality in a predetermined period with respect to each base station apparatus 30, and the base station apparatus 30 in which the result of the evaluation satisfies the predetermined base station priority condition B is a base station It may be selected as the connection destination of the own terminal apparatus 10 in preference to the selection result of the base station apparatus 30 based on the selection index. For example, the base station selection unit 15 targets each of the N base station apparatuses 30-1, ..., 30-N in a predetermined cycle (for example, every 10 minutes), The radio quality is measured for each beam transmitted from and the measurement results are recorded. Then, the base station selection unit 15 gives priority to a predetermined base station in recording of measurement results of m times (for example, 6 times for measurement every 10 minutes in 1 hour) in a predetermined period (for example, 1 hour) The base station apparatus 30 which satisfies the condition B is selected as the connection destination of the own terminal apparatus 10 with priority given to the selection result of the base station apparatus 30 based on the base station selection index. The base station priority condition B may be, for example, that the radio quality of the beam is the best at all measurement times in the recording of the measurement results of m measurements in a predetermined period. The radio quality of the beam may be, for example, a statistical value (for example, an average value or the like) calculated from the radio quality of all the beams of the base station apparatus 30, or the radio quality of all the beams of the base station apparatus 30 The maximum value, the minimum value, or the intermediate value in

(Modification 3)
The terminal device 10 may further include a notification unit that transmits the base station selection index of each base station device 30 to the base station device 30 to which the own terminal device 10 is connected. The base station apparatus 30 selects the base station apparatus 30 to which the terminal apparatus 10 changes connection based on the base station selection index of each base station apparatus 30 notified from the terminal apparatus 10 connected to itself. The terminal device 10 is notified of the connection change destination base station device 30 (base station ID) of the selection result. The communication control unit 14 of the terminal device 10 wirelessly connects (communications) wirelessly to the connection change destination base station device 30 (base station ID) notified from the base station device 30 to which the own terminal device 10 is connected. Change).

  Although the embodiments of the present invention have been described in detail with reference to the drawings, the specific configuration is not limited to this embodiment, and design changes and the like within the scope of the present invention are also included.

  For example, the embodiment described above may be applied in a wireless environment in which multiple reflections of radio waves occur, such as in railway cars, underground malls, back alleys, and valleys of multiple buildings. Moreover, you may apply the electromagnetic wave with strong straightness other than a millimeter wave to the electromagnetic wave which the radio | wireless communications system 1 utilizes for radio | wireless communication.

Alternatively, a computer program for realizing the functions of the respective devices described above may be recorded in a computer-readable recording medium, and the computer system may read and execute the program recorded in the recording medium. Note that the “computer system” referred to here may include an OS and hardware such as peripheral devices.
The “computer readable recording medium” is a writable non-volatile memory such as a flexible disk, an optical magnetic disk, a ROM, a flash memory, etc., a portable medium such as a DVD (Digital Versatile Disc), etc. Storage devices such as hard disks.

Furthermore, the “computer-readable recording medium” is a volatile memory (for example, DRAM (Dynamic Memory) inside a computer system that becomes a server or client when a program is transmitted via a network such as the Internet or a communication line such as a telephone line). As Random Access Memory), it is assumed that the program which holds the program for a fixed time is included.
The program may be transmitted from a computer system in which the program is stored in a storage device or the like to another computer system via a transmission medium or by transmission waves in the transmission medium. Here, the “transmission medium” for transmitting the program is 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.
Further, the program may be for realizing a part of the functions described above. Furthermore, it may be a so-called difference file (difference program) that can realize the above-described functions in combination with a program already recorded in the computer system.

DESCRIPTION OF SYMBOLS 1 radio | wireless communications system, 10 ... terminal unit, 11, 31 ... radio | wireless part, 12 ... base station search part, 13 ... base station selection index production | generation part, 14 ... communication control part, 15 ... base station selection part, 16 ... memory Unit, 30-1 to N: Base station apparatus, 32: Beam control unit

Claims (6)

In the terminal device of a wireless communication system comprising a terminal device and a plurality of base station devices,
A base station search unit which measures radio quality for each beam transmitted from the base station apparatus;
A base which calculates the number of connectable beams satisfying predetermined radio quality for each of the base station apparatuses, and generates a base station selection index indicating the degree of the number of connectable beams for each of the base station apparatuses A station selection indicator generation unit,
A communication control unit configured to wirelessly connect to a base station apparatus selected as a connection destination of its own terminal apparatus from among the plurality of base station apparatuses based on the base station selection index;
A terminal device comprising And a base station selection unit for selecting a base station apparatus to which the terminal apparatus is to be connected among the plurality of base station apparatuses based on the base station selection index.
The terminal device according to claim 1. The base station selection unit evaluates the measurement results of the radio quality in a predetermined period with respect to each of the base station apparatuses, and the base station apparatus whose evaluation result satisfies the predetermined base station priority condition is the base station apparatus. Selecting as the connection destination of the own terminal apparatus in preference to the selection result of the base station apparatus based on the station selection index;
The terminal device according to claim 2. And a notification unit that transmits the base station selection index to the base station apparatus currently connected.
The terminal device according to any one of claims 1 to 3. A base station selection method for a wireless communication system comprising a terminal device and a plurality of base station devices, comprising:
A base station search step in which the terminal apparatus measures radio quality for each beam transmitted from the base station apparatus;
The terminal apparatus calculates, for each of the base station apparatuses, the number of connectable beams satisfying predetermined radio quality, and the base station selection index indicating the degree of the number of connectable beams as the base station apparatus A base station selection index generation step of generating each time;
A communication control step of wirelessly connecting the terminal apparatus to a base station apparatus selected as a connection destination of the own terminal apparatus from among the plurality of base station apparatuses based on the base station selection index;
Base station selection method including: In a computer of the terminal device of a wireless communication system comprising a terminal device and a plurality of base station devices,
A base station search function of measuring radio quality for each beam transmitted from the base station apparatus;
A base which calculates the number of connectable beams satisfying predetermined radio quality for each of the base station apparatuses, and generates a base station selection index indicating the degree of the number of connectable beams for each of the base station apparatuses Station selection index generation function,
A communication control function of wirelessly connecting to a base station apparatus selected as a connection destination of the own terminal apparatus from among the plurality of base station apparatuses based on the base station selection index;
Computer program to make it happen.

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