JP6506217B2 - Mobile radio station control method, radio communication system and central control station - Google Patents

Description

  The present invention relates to control techniques for multiple radio stations.

In recent years, with the rapid spread of terminal devices such as smartphones and tablet terminals, users of large-capacity content by the terminal devices are increasing. As a result, the traffic volume on the wireless network is rapidly increasing. For example, in the 5th generation mobile communication (5G) system currently under consideration, the requirement is to increase the transmission capacity per unit area by 1000 times (× 1000 capacity / km ² ) compared to the 4th generation macrocell environment. I have listed. For this purpose, we consider the necessity to mutually complement and introduce highly efficient offload to wireless LAN (Local Area Network) etc., technology to operate high density small cells efficiently. (See, for example, Non-Patent Document 1). In Non-Patent Document 1, the goal is to improve the number of cells per unit area (cell / km 2) by 10 times.

  Densification of networks with small cells having base station devices with low transmission power is promising as a solution that efficiently supports explosive growth of traffic, particularly in areas such as high traffic hot spots. A small cell covering a local area in a macro cell covering a wide area is additionally arranged, and different frequencies are used between the macro cell and the small cell. By applying carrier aggregation in the central control station, throughput improvement and capacity increase are realized by small cells (add-on cells) added while maintaining connectivity.

  Also in the wireless LAN, utilization of offload using an unlicensed band is also actively studied (see, for example, Non-Patent Document 2). In addition, as an index for evaluating traffic offload, define the total amount of data generated by the amount of data transmitted by Wi-Fi (Wireless Fidelity) as the offload efficiency, and improve the offload efficiency. Have evaluated traffic offload as an index that can be efficiently performed (see, for example, Non-Patent Document 3). As described above, it is considered important to efficiently perform traffic offload, which reduces the load on the cellular base station which is a wide coverage area by creating a local coverage area.

  As an example of local traffic increase, it is generally considered that the traffic in the area increases as the number of users increases, particularly in an event hall where many users use terminal devices. Such an environment increases the user density at a specific time, and furthermore, the area in which the users are concentrated varies depending on the situation. The technology described in Non-Patent Document 4 performs channel assignment control by centrally controlling a plurality of wireless LAN access points, and may respond to fluctuations in time and distribution. However, the technology described in Non-Patent Document 4 is premised on densely arranging tens of base station apparatuses in a dense manner.

  In the small area base station apparatus for traffic offload, it can be expected that the offload efficiency increases as the number increases. However, it is not realistic because it is necessary to place the base station apparatus in the entire area where the concentration of users is expected. Also in Non-Patent Document 5, although the base station apparatus performs antenna beam control according to user distribution using a multi-element antenna, it is premised that all base station apparatuses possess a multi-element antenna. Therefore, in addition to the cost being increased, it is inevitable that a large number of base station apparatuses are required to improve the planar frequency utilization efficiency in a time-varying local user dense area as in Non-Patent Document 4.

  In order to solve the above-mentioned problems, a method is needed to accommodate more users in a variable user crowded area, using a limited number of offload radio stations. In Non-Patent Document 6, in order to improve the offload efficiency, a technology is proposed in which the base station apparatus dynamically changes the position according to the fluctuation of the user distribution. By using the technology described in Non-Patent Document 6, it is possible to adaptively deploy base station apparatuses in a local area, so it is expected that efficient traffic offload will be achieved with limited base station apparatuses. it can.

  However, in the technology described in Non-Patent Document 6, the use of a clustering method called k-means method described in Non-Patent Document 7 is considered to accommodate terminal devices in four base station devices. . The k-means method is an algorithm for minimizing the average distance between the base station apparatus and the terminal apparatus, and is not an algorithm that takes into consideration the density of the terminal apparatus for the service area. Non-Patent Document 8 proposes a technique for dynamically arranging a base station apparatus according to a rapid population change or a traffic change using a movable base station apparatus (hereinafter referred to as a "mobile radio station"). There is.

NTT DOCOMO, “DOCOMO 5G White Paper”, 2014 NTT DOCOMO, INC. All Rights Reserved, (Sep. 2014). Bangerter, Boyd, et al. "Networks and Devices for the 5G Era", IEEE Communications Magazine 52.2 (2014): 90-96. Lee, Kyunghan, et al. "Mobile Data Offloading: How Much Can WiFi Deliver?", IEEE / ACM Transactions on Networking (TON) 21.2 (2013): 536-550. B. A. H. S. Abeysekera, K. Ishihara, Y. Inoue, and M. Mizoguchi, "Network-controlled Channel Allocation Scheme for IEEE 802.11 Wireless LANs: Experimental and Simulation Study" Proc. IEEE VTC '14-Spring, May. 2014. Daisuke Matsuo, Motoki Morita, Takahiro Nobuhiro, Yasuhiko Matsunaga, "B-5-33 A Proposal of a Cover Area Control Method Adaptively Housing Dense Users (B-5. Wireless Communication System A (Mobile Communication) A)". Electron Proceedings of the IEICE General Conference 2015.1 (2015): 388. Takuto Arai, Daisuke Goto, Fumi Iwabuchi, Akihiko Iwakuni, Ikki Maruta, "Proposal of Adaptive Mobile AP System to Realize Off-Road Efficiency Improvement" "Shingaku Technique, RCS2016-43, pp. 107-112, May. 2016. J. Macqueen, "SOME METHODS FOR CLASSIFICATION AND ANALYSIS OF MULTIVARIATE OBSERVATIONS", Proc. Of 5th Berkeley Symposium on Mathematical Statistics and Probability, pp. 281-297, 1967. Bhattarai Sulabh, et al. “Optimizing the Location of Dynamic Mobile Base Stations”, Computing, Networking and Communications (ICNC), 2015 International Conference on Computing Networking and Communications, Invited Position Papers, IEEE, 2015.

  However, the guidelines of the technology described in Non-Patent Document 8 are designed to minimize the moving distance of the mobile radio station. Therefore, in the various techniques described above, there is a problem that the offload efficiency can not be improved in the area where the terminal devices are concentrated.

  In view of the above circumstances, the present invention aims to provide a technology that can improve offload efficiency.

  According to one aspect of the present invention, there is mainly provided a plurality of movable mobile radio stations that perform communication for the purpose of offloading with a terminal device, and a communication range wider than the communication range of the plurality of mobile radio stations. A mobile radio station control method in a radio communication system comprising a radio station, and a central control station for controlling the plurality of mobile radio stations and the main radio station, wherein the central control station is located around the mobile radio station. A terminal information collecting step of collecting terminal information including information on a distribution of the terminal devices located; and the central control station has a frequency at which neither the main radio station nor the plurality of mobile radio stations exert interference. As described above, the frequency used by the main radio station and the plurality of mobile radio stations is determined, and the end is determined based on the area in which the terminal devices are obtained from the collected terminal information. The position of the mobile radio station is determined based on the determined position and frequency of the placement destination, by determining the location where the device is distributed and the average distance between the mobile wireless station and the terminal device is minimized. Mobile wireless station control method comprising: control steps of controlling a plurality of mobile wireless stations; and control steps of controlling the movement of the mobile wireless station and the frequency used by the mobile wireless station according to control by the central control station. It is.

  One aspect of the present invention is the mobile wireless station control method described above, wherein the central control station calculates, in the control step, the centers of gravity of all the terminal devices present in an area in which the terminal devices are concentrated. The position of the arrangement destination of the plurality of mobile radio stations is determined by clustering all the terminal devices present in the area obtained based on the calculated center of gravity.

  One aspect of the present invention is the mobile radio station control method described above, wherein the central control station uses the calculated center of gravity in the control step to determine the total number of terminal devices based on an area centered on the center of gravity. The area where the ratio is a predetermined ratio is set, and the process of obtaining the center of gravity of all the terminal devices present in the set area is repeated until the center of gravity does not change in a predetermined range, and the center of gravity does not change The position of the arrangement destination of the plurality of mobile radio stations is determined such that the average distance from the terminal device present in the area to the nearest mobile radio station is minimized.

  According to one aspect of the present invention, there is mainly provided a plurality of movable mobile radio stations that perform communication for the purpose of offloading with a terminal device, and a communication range wider than the communication range of the plurality of mobile radio stations. A radio communication system comprising: a radio station; and a central control station for controlling the plurality of mobile radio stations and the main radio station, wherein the central control station is the terminal device located around the mobile radio station. A terminal information collection unit for collecting terminal information including information on distribution; and the main radio station and the plurality of movable radios such that the frequency does not cause interference with any of the main radio station and the plurality of mobile radio stations. Determine the frequency used by the station, disperse the terminal devices based on the area in which the terminal devices are densely obtained from the collected terminal information, and distribute the mobile wireless station and the terminal devices A control unit for determining the position at which the mobile wireless station is located at a position at which the average distance of the mobile stations is minimized, and controlling the plurality of mobile wireless stations based on the determined position and frequency of the deployed position; The mobile wireless station is a wireless communication system including a control unit that controls the frequency used by the device according to control of the central control station and movement of the device.

  According to one aspect of the present invention, there is mainly provided a plurality of movable mobile radio stations that perform communication for the purpose of offloading with a terminal device, and a communication range wider than the communication range of the plurality of mobile radio stations. A central control station in a radio communication system comprising a radio station, and a central control station for controlling the plurality of mobile radio stations and the main radio station, which relates to the distribution of the terminal devices located around the mobile radio station A terminal information collection unit for collecting terminal information including information; and the main radio station and the plurality of mobile radio stations such that the frequency does not cause interference with any of the main radio station and the plurality of mobile radio stations. The frequency to be used is determined, the terminal devices are dispersed based on the area where the terminal devices are densely obtained from the collected terminal information, and the mobile wireless station and the terminal device Controlling the plurality of mobile wireless stations based on the determined location and frequency of the placement destination determined as the location of the placement destination of the mobile wireless station, and determining a position that minimizes the average distance of It is a station.

  The present invention makes it possible to improve offload efficiency.

It is a figure which shows the system configuration | structure of the radio | wireless communications system 100 in this invention. It is a figure which shows an example of the frequency band which a radio station uses. FIG. 2 is a schematic block diagram showing functional configurations of a central control station 10 and a mobile radio station 30. It is a figure which shows the specific example of a mobile radio station information table. 5 is a flowchart showing the flow of processing of the central control station 10. It is a figure for demonstrating the process which determines the arrangement | positioning destination of the mobile radio station 30. FIG. It is a figure for demonstrating the process which determines the arrangement | positioning destination of the mobile radio station 30. FIG. It is a figure for demonstrating the process which determines the arrangement | positioning destination of the mobile radio station 30. FIG. It is a figure which shows the verification result of the effect of this invention. It is a figure for demonstrating a position estimation method.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 is a diagram showing a system configuration of a wireless communication system 100 in the present invention.
The radio communication system 100 includes a central control station 10, a main radio station 20, and a plurality of mobile radio stations 30. The central control station 10 and the main radio station 20, and the central control station 10 and the plurality of mobile radio stations 30 are communicably connected by wire or wirelessly. The plurality of mobile wireless stations 30 are provided in an area (hereinafter referred to as a "service area") (in FIG. 1, represented as "SA") in which a large number of terminal devices 40 exist. In the following description, the main radio station 20 and the mobile radio station 30 will be simply described as a radio station, unless otherwise distinguished. The main radio station 20 is a macrocell base station apparatus, and the mobile radio station 30 is a small cell base station apparatus.

Next, preconditions for applying the wireless communication system 100 in the present invention will be described.
The terminal device 40 communicates with one mobile radio station 30.
The terminal device 40 in the service area has a communication means with the main radio station 20 other than the mobile radio station 30, and the communication by the mobile radio station 30 is intended for traffic offload. For example, when the terminal device 40 is a cellular type terminal device, the terminal device 40 in the service area uses the mobile wireless station 30 in this method as a form to supplement communication with the macro cell base station (main radio station 20) Treat as a device to

The central control station 10 is configured using an information processing apparatus such as a personal computer. Central control station 10 controls main radio station 20 and mobile radio station 30. For example, the central control station 10 sets the frequency band used by the main radio station 20 and the mobile radio station 30, and determines the position of the arrangement destination of the mobile radio station 30.
The main radio station 20 is a base station apparatus fixed at a preset position. The main radio station 20 communicates with the terminal device 40. The communication range of the main radio station 20 is wider than the communication range of the mobile radio station 30. For example, the communication range of the main radio station 20 is the entire service area.

The mobile radio station 30 is a movable base station apparatus. The mobile wireless station 30 performs wireless communication with the terminal device 40. The mobile radio station 30 performs setting of the frequency used by its own device and movement to the arrangement destination according to the control of the central control station 10. The range in which the mobile wireless station 30 moves is within an area that can be covered by the wireless communication system 100.
The terminal device 40 is configured using, for example, an information processing device such as a smartphone, a mobile phone, a tablet terminal, or a notebook computer. The terminal device 40 communicates with the main radio station 20 or the mobile radio station 30.

  FIG. 2 is a diagram illustrating an example of a frequency band used by a wireless station. As shown in FIG. 2, each wireless station (main wireless station 20 and mobile wireless station 30) uses different frequency bands. Thus, it is assumed that the wireless stations do not interfere with each other. When a plurality of small cell base stations (for example, mobile radio stations 30) are arranged in the service area, in addition to using a frequency different from that of the macro cell base station (for example, the main radio station 20) Also, it is necessary to prevent interference by setting different frequency bands. In the wireless LAN, interference can be avoided by having the central control station 10 select different channels for the approaching wireless stations in advance.

FIG. 3 is a schematic block diagram showing functional configurations of central control station 10 and mobile radio station 30. As shown in FIG.
First, the functional configuration of the central control station 10 will be described. The central control station 10 includes a CPU (Central Processing Unit), a memory, an auxiliary storage device, and the like connected by a bus, and executes a control program. By execution of the control program, the central control station 10 functions as an apparatus including the information collection unit 11, the storage unit 12, the control unit 13, and the control information notification unit 14. Note that all or part of the functions of the central control station 10 may be realized using hardware such as an application specific integrated circuit (ASIC), a programmable logic device (PLD), or a field programmable gate array (FPGA). . Also, the control program may be recorded on a computer readable recording medium. The computer readable recording medium is, for example, a portable medium such as a flexible disk, a magneto-optical disk, a ROM, a CD-ROM, or a storage device such as a hard disk built in a computer system. Also, the control program may be transmitted and received via a telecommunication line.

The information collection unit 11 collects terminal information from the mobile radio station 30. The terminal information represents the position information of the terminal device 40 located around the mobile radio station 30, and the position information of the mobile radio station 30. Position information is, for example, latitude and longitude.
The storage unit 12 includes a terminal device position information storage unit 121 and a mobile radio station information storage unit 122. The terminal device position information storage unit 121 is configured using a storage device such as a magnetic hard disk drive or a semiconductor storage device. The terminal device position information storage unit 121 stores the position information of the terminal device 40. The mobile radio station information storage unit 122 is configured using a storage device such as a magnetic hard disk drive or a semiconductor storage device. The mobile radio station information storage unit 122 stores a mobile radio station information table.

  FIG. 4 is a diagram showing a specific example of the mobile radio station information table. The mobile radio station information table has a plurality of records (hereinafter referred to as “mobile radio station information records”) representing information related to the mobile radio station 30. As shown in FIG. 4, the mobile wireless station information record has the following values: wireless station ID, position information, used frequency, position information after determination, and the number of accommodated terminal devices. The value of the wireless station ID is identification information for identifying the mobile wireless station 30, and is, for example, the MAC address of the mobile wireless station 30. The value of the position information represents the position where the mobile radio station 30 is currently located. The value of the used frequency represents the frequency used by the mobile radio station 30. The value of the position information after determination represents the position where the mobile wireless station 30 determined by the processing by the control unit 13 is disposed. The value of the number of accommodated terminal devices represents the number of terminal devices 40 accommodated by the mobile radio station 30.

Returning to FIG. 3, the description of the central control station 10 will be continued.
The control unit 13 controls the main radio station 20 and the mobile radio station 30. For example, the control unit 13 determines the position of the arrangement destination of the mobile wireless station 30 based on the information stored in the storage unit 12. Also, for example, the control unit 13 determines the frequency used by each wireless station so that the frequencies used by the main wireless station 20 and the mobile wireless station 30 are different.
The control information notification unit 14 notifies the mobile radio station 30 of control information including the position information of the arrangement destination determined by the control unit 13. Also, the control information notification unit 14 notifies the main radio station 20 and the mobile radio station 30 of control information including the frequency information determined by the control unit 13.

Next, the functional configuration of the mobile radio station 30 will be described.
The mobile radio station 30 includes a CPU, a memory, an auxiliary storage device, and the like connected by a bus, and executes a mobile base station program. By executing the mobile base station program, the mobile radio station 30 functions as an apparatus including the information collection unit 31, the communication unit 32, the control unit 33, and the movable unit 34. Note that all or part of the functions of the mobile radio station 30 may be realized using hardware such as an ASIC, a PLD, or an FPGA. Also, the mobile base station program may be recorded on a computer readable recording medium. The computer readable recording medium is, for example, a portable medium such as a flexible disk, a magneto-optical disk, a ROM, a CD-ROM, or a storage device such as a hard disk built in a computer system. Also, the mobile base station program may be transmitted and received via a telecommunication line.

The information collection unit 31 collects terminal information periodically (for example, every hour). The information collecting unit 31 may collect terminal information at irregular intervals (for example, a preset time, timing when an instruction is given). Position information may be acquired using a positioning function such as GPS (Global Positioning System).
The communication unit 32 communicates with the central control station 10. For example, the communication unit 32 transmits the terminal information collected by the information collection unit 31 to the central control station 10. Also, for example, the communication unit 32 receives the control information notified from the central control station 10.

The control unit 33 controls the own device based on the control information received by the communication unit 32. For example, the control unit 33 controls the movable unit 34 to move the own device to the placement destination based on the location information of the placement destination included in the control information. The control unit 33 may automatically control the movable unit 34 based on the position information of the arrangement destination, or may control the movable unit 34 according to an instruction of the user operating the movable wireless station 30. .
The movable unit 34 moves the device itself according to the control of the control unit 33. For example, the movable portion 34 is a tire or the like.

FIG. 5 is a flowchart showing the flow of processing of the central control station 10. In the description of FIG. 5, it is assumed that a large number of terminal devices 40 exist in the service area as shown in FIG.
The information collecting unit 11 collects terminal information from each mobile radio station 30 (step S101). The information collection unit 11 stores the collected terminal information in the storage unit 12. Specifically, the information collection unit 11 stores the position information of the terminal device 40 included in the terminal information in the terminal device position information storage unit 121, and the position information of the movable wireless station 30 included in the terminal information is The mobile radio station information storage unit 122 stores the information in association with the identification information of the station 30.

The control unit 13 calculates the centers of gravity (X, Y) of all the terminal devices 40 in the service area based on the terminal information stored in the storage unit 12 (step S102). Specifically, when the control unit 13 sets the number of terminal devices 40 in the service area to N _all and the position coordinates of the terminal devices 40-n (n is an integer of 1 or more) to (x _n , y _n ), The center of gravity (X, Y) of all the terminal devices 40 in the service area is calculated based on the following equation 1 (see FIG. 6A). In FIG. 6A, a circle 3-1 represents a communicable area covered by the mobile radio station 30-1.

Next, as shown in FIG. 6B, the control unit 13 generates a circle 50 of radius d centered on the calculated center of gravity (X, Y) (step S103). At this time, the control unit 13, the number of terminal devices 40 in a circle and Nc, calculating the maximum radius d satisfying R ≧ Nc / N _all, to generate a circle corresponding to the calculated radius d. Here, R represents the ratio of the number of terminal devices 40 accommodated in an area (hereinafter referred to as “target area”) to be targeted for improving offload efficiency among all the terminal devices 40 in the service area. . The target area is, for example, an area in which the terminal devices 40 are concentrated. For example, in the case where an area in which 80% of the terminal devices 40 in the total number of terminal devices in the service area exist is set as a target area, R = 0.8. R may be set in advance or may be input each time processing is performed.

Next, the control unit 13 calculates the centroids (Xu, Yu) of all the terminal devices 40 in the circle (circle 50 shown in FIG. 6B) generated in the process of step S103 (step S104). The method of calculating the center of gravity (Xu, Yu) is the same as the method of calculating the center of gravity (X, Y). In this case, the control unit 13 sets the number of all terminal devices in the target area as N _all and the position coordinates of the terminal device 40-n as (x _n , y _n ) in the above equation 1 based on the above equation 1 The center of gravity (Xu, Yu) of all the terminal devices 40 in the inside is calculated (see FIG. 7A).

  Thereafter, the control unit 13 determines whether (Xu = X) and (Yu = Y) (step S105). When it is determined that (Xu = X) and (Yu = Y) are not satisfied (step S105-NO), the control unit 13 sets Xu calculated in the process of step S104 as a new X and Yu as a new Y. (Step S106) The processing of steps S103 to S105 is repeatedly executed until (Xu = X) and (Yu = Y).

On the other hand, when it is determined that (Xu = X) and (Yu = Y) (step S105-YES), the control unit 13 calculates the center of gravity (Xu, Yu) as shown in FIG. 7B. A circle 51 of radius du centering on is generated (step S107). Under the present circumstances, the control part 13 sets the number of the terminal devices 40 in a circle | round | yen to Nc, calculates the largest radius du which satisfy | fills R> = Nc / N _all , and produces | generates the circle according to the calculated radius du. Thereafter, as shown in FIG. 8A, the control unit 13 temporarily sets the center points of each cluster at equal intervals at positions separated by a fixed distance d _ap (<du) from the center of gravity (Xu, Yu) ( Step S108). This center point represents the position of the arrangement place of the mobile radio station 30.

The control unit 13 applies the k-means method only to the terminal device 40 in the circle 51, and performs clustering by the mobile wireless station 30 (step S109). The k-means method is a clustering algorithm that determines the position of the mobile wireless station 30 such that the average distance from each terminal device 40 to the nearest mobile wireless station 30 is minimized, and is performed according to Equation 2 below. . First, the initial barycentric coordinates x _i (with-above x) (i is an integer of 1 or more) are determined at k points, and the whole terminal device 40 is divided into the nearest x _i- . Calculating the centroid coordinates of each cluster set X _i after Clustering, new barycentric coordinates x _i - defined as. After updating the barycentric coordinates, all the terminal devices 40 are again divided into the closest x _i −. The above operation is repeated until the objective function f shown in Equation 2 below converges.

Here, x _n in the above equation 2 represents the position coordinates of the terminal device 40-n, and N _i represents the number of elements of X _i . The control unit 13 determines the center point of each of the determined clusters as the position of the arrangement destination of the mobile wireless station 30 (step S110) (see FIG. 8B). The control unit 13 stores the information on the determined position of the arrangement destination of each mobile radio station 30 in the mobile radio station information storage unit 122 in association with the identification information of the mobile radio station 30. The control information notification unit 14 transmits control information including information on the determined arrangement destination of each mobile wireless station 30 to each mobile wireless station 30 (step S111).

  FIG. 9 is a diagram showing verification results of the effects of the present invention. FIG. 9 shows verification results of three patterns in the case where the technology of the present invention is applied in the case where the mobile radio station 30 is fixedly arranged and in which the k-means method is applied. Further, as a condition for verification, in the ± 200 m square service area, the number of mobile wireless stations 30 is four, the number of terminal devices 40 is 100, and each terminal device 40 is accommodated in the nearest mobile wireless station 30 It shall be. The terminal device distribution sets hot spots in which the terminal devices 40 are concentrated at random positions in order to create a congested situation at a specific position. The radius of the hotspot is 30 m, and it is assumed that 80% of the total number of terminal devices 40 exist in the hotspot.

  In the fixed arrangement, the mobile radio station 30 is fixedly arranged at four locations of (X, Y) = (+ 75, +75), (-75, +75), (+75, -75), and (-75, -75). ing. The four circles are the communication areas (set to a radius of 100 m) of the respective movable radio stations 30, and the movable radio station 30 is assumed to be located at the center of the circle. The distribution of the terminal device 40 is plotted with different markers depending on the mobile radio station 30 accommodated. As shown in FIG. 9, it can be seen that in the fixed arrangement, the terminal device 40 is concentrated on the first mobile radio station 30. On the other hand, when the k-means method is applied to the terminal device 40 in the service area, the distance between each mobile radio station 30 and the terminal device 40 accommodated by the own device is short. Although it understands, the ratio of terminal device 40 accommodation by the terminal device 40 does not see fixed arrangement and a change. On the other hand, when the technology of the present invention is set to R = 0.8 and applied, the dense area of the terminal device 40 (an area in which the AP1 accommodating terminal device to the AP4 accommodating terminal device in FIG. It can be seen that the mobile radio station 30 (AP1 to AP4 in FIG. 9) moves, and a number of terminal devices 40 are evenly distributed. As described above, it is understood that the wireless station position design is possible in which the dense area of the terminal device 40 is accommodated in a concentrated and distributed manner by the technique in the present invention.

According to the wireless communication system 100 configured as described above, the offload efficiency can be improved. Hereinafter, this effect will be specifically described.
The central control station 10 disperses, based on the information collected from the mobile radio station 30, the terminal devices 40 accommodated in the target area, which is an area in which the distribution of the terminal devices 40 is high in the entire service area, Also, the position at which the average distance between the mobile radio station 30 and the terminal device 40 is minimized is determined as the position of the arrangement destination of each mobile radio station 30. This makes it possible to improve load distribution and average received power, and to improve offload efficiency.
Further, by moving the mobile wireless station 30 to the area where the terminal device 40 concentrates, the proportion of the terminal device 40 in which the propagation distance to the mobile wireless station 30 becomes short increases, and the propagation loss can be reduced. Therefore, the effect of power saving of the terminal device 40 and improvement of average received power can be expected.

<Modification>
The central control station 10 may perform the position estimation method using the technique described in reference 1. Reference 1 describes a method of performing position estimation using a plurality of mobile radio stations 30 and using received signal strength indicator (RSSI) of a terminal device 40. For example, as shown in FIG. 10, in the wireless LAN system, each mobile wireless station 30 can acquire the RSSI of the terminal device 40. The central control station 10 calculates the estimated distance from the RSSI, and uses the plurality of terminal devices 40 to estimate the position by triangulation.
(Reference 1: Mazuelas, Santiago, et al. "Robus indoor positioning provided by real-time RSSI values in unmodified WLAN networks." IEEE Journal of selected topics in signal processing 3.5 (2009): 821-831.)

  The embodiment of the present invention has been described in detail with reference to the drawings. However, the specific configuration is not limited to this embodiment, and includes design and the like within the scope of the present invention.

DESCRIPTION OF SYMBOLS 10 Central control station 20 Main radio station 30 Mobile radio station 40 Terminal device 11 Information collecting unit 12 Storage unit 121 Terminal device position information storage unit 122 Mobile radio station information storage , 13 ... control unit, 14 ... control information notification unit, 31 ... information collection unit, 32 ... communication unit, 33 ... control unit, 34 ... movable unit

Claims (5)

A plurality of movable mobile stations performing communication for the purpose of offloading with a terminal device, a main radio station covering a communication range wider than the communication range of the plurality of mobile stations, and the plurality of mobile stations A mobile radio station control method in a radio communication system comprising: a mobile radio station and a central control station controlling the main radio station,
A terminal information collecting step in which the central control station collects terminal information including information on a distribution of the terminal devices located around the mobile radio station;
The central control station determines the frequency used by the main radio station and the plurality of mobile radio stations so that the main radio station and the plurality of mobile radio stations do not interfere with each other, and collects the frequencies The movable terminal is dispersed based on the area where the terminal devices are densely obtained from the terminal information obtained, and the movable position is minimized such that the average distance between the movable wireless station and the terminal device is minimized. Controlling the plurality of mobile wireless stations based on the determined location and frequency of the placement location determined as the placement location of the wireless station;
A control step in which the mobile wireless station controls the frequency used by the device according to the control of the central control station and the movement of the device;
A mobile radio station control method comprising:   The central control station calculates, in the control step, the centers of gravity of all the terminals present in the area in which the terminals are dense, and all the terminals present in the area obtained based on the calculated centers of gravity The mobile radio station control method according to claim 1, wherein the position of the arrangement destination of the plurality of mobile radio stations is determined by clustering the   The centralized control station sets an area in which the number of all terminal devices is a predetermined ratio based on an area centered on the center of gravity using the calculated center of gravity in the control step, and exists in the set area The process of obtaining the center of gravity of all the terminal devices to be performed is repeated until the center of gravity does not change in a predetermined range, and the average distance from the terminal devices present in the area where the center of gravity does not change to the nearest mobile radio station is The mobile radio station control method according to claim 2, wherein the position of the arrangement destination of the plurality of mobile radio stations is determined so as to be minimized. A plurality of movable mobile stations performing communication for the purpose of offloading with a terminal device, a main radio station covering a communication range wider than the communication range of the plurality of mobile stations, and the plurality of mobile stations A wireless communication system comprising: a mobile wireless station; and a central control station that controls the main wireless station,
The central control station
A terminal information collection unit that collects terminal information including information on the distribution of the terminal devices located around the mobile radio station;
The frequency used by the main radio station and the plurality of mobile radio stations is determined so that the main radio station and the plurality of mobile radio stations do not interfere with each other, and the collected terminal information is determined Based on the area where the obtained terminal devices are concentrated, the terminal devices are dispersed, and a position at which the average distance between the mobile wireless station and the terminal device is minimized is the location where the mobile wireless stations are disposed. A control unit that determines the position and controls the plurality of mobile wireless stations based on the determined position and frequency of the placement destination;
Equipped with
The mobile radio station is
A control unit that controls the frequency used by the device according to the control of the centralized control station and the movement of the device;
A wireless communication system comprising: A plurality of movable mobile stations performing communication for the purpose of offloading with a terminal device, a main radio station covering a communication range wider than the communication range of the plurality of mobile stations, and the plurality of mobile stations A central control station in a wireless communication system, comprising: a mobile wireless station and a central control station controlling the main wireless station,
A terminal information collection unit that collects terminal information including information on the distribution of the terminal devices located around the mobile radio station;
The frequency used by the main radio station and the plurality of mobile radio stations is determined so that the main radio station and the plurality of mobile radio stations do not interfere with each other, and the collected terminal information is determined Based on the area where the obtained terminal devices are concentrated, the terminal devices are dispersed, and a position at which the average distance between the mobile wireless station and the terminal device is minimized is the location where the mobile wireless stations are disposed. A control unit that determines the position and controls the plurality of mobile wireless stations based on the determined position and frequency of the placement destination;
Central control station with.

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