JP5339370B2 - Wireless communication system and base station activation method for reducing power consumption of entire base station - Google Patents

Description

  The present invention relates to a radio communication system and a base station activation method that reduce power consumption of the entire base station.

  Reduction of power consumption in communication devices has become necessary not only for reducing energy costs but also for environmental considerations such as reducing carbon dioxide emissions. In particular, the amount of power consumed by mobile phone communication base stations may occupy approximately 60% of the amount of power consumed by mobile phone operators (see Non-Patent Document 1, for example). Therefore, in recent years, a wireless communication system with low power consumption, that is, an environmentally friendly wireless communication system has been researched and developed.

  A wireless terminal is generally a mobile terminal (smart phone, PAD, notebook computer, etc.), and has a battery. Therefore, many studies have been made on techniques for reducing power consumption. For example, according to a wireless local area network (LAN), a wireless terminal that is not operated by a user can be automatically stopped (or suspended), and the wireless terminal can be started remotely via an access point (for example, patents). References 1-4).

  In addition, according to the cellular phone communication system, power consumption in the entire system can be reduced by stopping some base stations (stopping the power amplifier or turning off the power) during a time zone with a small amount of communication traffic. can do. The time zone with a small amount of communication traffic is, for example, the night in the city center.

  There is also a technique for installing a small base station (access point) constituting a femto / pico / microcell with a small service radius indoors for a large base station for a mobile phone (see, for example, Patent Document 5). According to this technique, since the small base station always activates the wireless communication interface, the power consumption is relatively high. Therefore, there is a technique for reducing the power consumption by reducing the activation duration of the radio interface by stopping some small base stations during a time period when the amount of communication traffic decreases, such as at night (for example, non-patent literature). 2).

JP 2008-205799 A JP 2006-060336 A JP 2005-018377 A JP 2003-299160 A JP 2007-129405 A JP 2008-109521 A JP 2005-184482 A

Vodafone UK publishes CorporateResponsibility Report-CR Review 2007/08 Haruki Izumikawa, Dirk Kutscher, Yoji Kishi, "DelayTolerance for Energy-Efficient Mobile Communications", IEICE Society Conference, September 2009, [online], [October 26, 2009 search], Internet <URL: http://secure1.gakkai-web.net/gakkai/ieice/program2/html/index/au_alpha_main.html> "Signal processing / beam control method / configuration / weight control based on arrival direction estimation", [online], [searched on November 5, 2009], Internet <URL: http://www.jpo.go.jp /shiryou/s_sonota/hyoujun_gijutsu/arrayantenna/3-4-10.pdf> T. Hain, “An IPv6 Provider-Independent Global Unicast Address Format” F. v. Megen, P. Muller, “Mapping Universal Geographical Area Description (GAD) to IPv6 Geo Based Unicast Addresses” P. Vishwanath, D. Tse, R. Laroia, “Opportunistic Communication: A New System Design”, IT 2002, [online], [searched November 5, 2009], Internet <URL: www.stanford.edu/class /ee360/lecture8_wonchae.ppt> Ryosuke Amano, Toshiyuki Maeyama, Takashi Inoue, Yoshio Takeuchi, “Study of Simple Beam Control Antenna in Packet Cellular System”, IEICE Mobile Communication Workshop, March 2005, [online], [November 6, 2009 Day search], Internet <URL: http: //ci.nii.ac.jp/naid/110003204616/>

  According to the techniques described in Patent Literatures 1 to 4, activation / stop of a small base station or an access point is not controlled. Further, according to the technique described in Patent Document 5, the transmission power of the base station is controlled based on feedback information from the wireless terminal, and is a technique for reducing interference. That is, it does not reduce power consumption. Furthermore, according to the technique described in Non-Patent Document 2, it is completely disclosed which base station is controlled to start / stop at what timing and for what time in order to reduce power consumption. Not.

  Therefore, according to the present invention, there is provided a radio communication system and a base station control method capable of reducing the power consumption of the entire base station by adaptively starting and controlling a small base station according to communication traffic. For the purpose.

According to the present invention, a large base station with a wide radio wave coverage, a small base station with a narrow radio wave reach and installed within the radio wave reach of the large base station, and both the large base station and the small base station communicate with each other. A wireless communication system having a wireless terminal capable of
It further has a management device that controls the activation of the small base station,
The large base station has radio wave arrival direction detection means for detecting the arrival direction of radio waves from the wireless terminal, and radio wave arrival direction notification means for transmitting information on the arrival direction of radio waves from the wireless terminal to the management device,
The management device has terminal counting means for determining whether or not the number of wireless terminals or the amount of communication traffic is a predetermined number or more for each radio wave arrival direction, and the number of wireless terminals or the amount of communication traffic is a predetermined number or more And an activation signal transmitting means for transmitting an activation signal to be activated to a small base station located in the arrival direction of the radio wave,
The small base station is activated when an activation signal is received from the management apparatus, and when there is no active wireless terminal around it , the small base station is automatically stopped after the first predetermined time has elapsed, and the active wireless terminal around that Is present, the communication is automatically stopped after the second predetermined time has elapsed after the communication of all the wireless terminals has been completed .

According to another embodiment of the wireless communication system of the present invention,
The large base station has a sector antenna,
Preferably, the radio wave arrival direction detection means divides the radio wave arrival direction into a predetermined angle or a predetermined area range, and detects the radio wave arrival direction from the wireless terminal.

According to another embodiment of the wireless communication system of the present invention,
The large base station has an array antenna,
The radio wave arrival direction detecting means divides the radio wave arrival direction into a predetermined angle or a predetermined area range, changes the radio wave radiation direction by controlling the transmission array weight vector, and detects the radio wave arrival direction from the wireless terminal. It is also preferable.

According to another embodiment of the wireless communication system of the present invention,
About large base stations
The radio wave arrival direction detection means further detects the distance between the wireless terminal,
The radio wave arrival direction notifying means further transmits information on the distance to the wireless terminal to the management device,
About management device
The terminal counting means determines whether the number of wireless terminals or the amount of communication traffic is a predetermined number or more for each area based on the arrival direction and distance of radio waves,
The activation signal transmitting means preferably transmits an activation signal to be activated to a small base station located in the range of the arrival direction and distance of the radio wave when the number of wireless terminals or the amount of communication traffic is a predetermined number or more. .

  According to another embodiment of the wireless communication system of the present invention, it is also preferable that the management apparatus is integrally mounted on the large base station.

According to another embodiment of the wireless communication system of the present invention,
The activation signal transmission means of the management device includes the position range information of the small base station to be activated in the activation signal,
The small base station is also preferably activated when the position range of the position range information included in the activation signal includes the position of the small base station.

According to another embodiment of the wireless communication system of the present invention, the large base station may be a base station for mobile phone communication, and the small base station may be a base station for femtocell , picocell, or microcell. preferable.

  According to another embodiment of the wireless communication system of the present invention, the wireless terminal has one communication interface of the same communication method in order to communicate with the large base station and the small base station, or different communication methods. It is also preferable to have two communication interfaces.

According to the present invention, a large base station with a wide radio wave coverage, a small base station with a narrow radio wave reach and installed within the radio wave reach of the large base station, and both the large base station and the small base station communicate with each other. A base station activation method in a wireless communication system having a wireless terminal capable of
It further has a management device that controls the activation of the small base station,
A first step in which a large base station detects the direction of arrival of radio waves from a wireless terminal;
A second step in which the large base station transmits information on the arrival direction of the radio wave from the wireless terminal to the management device;
A third step in which the management device determines whether the number of wireless terminals or the amount of communication traffic is greater than or equal to a predetermined number for each radio wave arrival direction;
A fourth step of transmitting an activation signal to be activated to the small base station located in the arrival direction of the radio wave when the number of wireless terminals or the amount of communication traffic is equal to or greater than a predetermined number,
When the small base station receives an activation signal from the management apparatus and there is no active wireless terminal around it , the small base station automatically stops after the first predetermined time has passed, and is active around that And a fifth step of automatically stopping after a second predetermined time has elapsed after the communication of all the wireless terminals is completed .

  According to the wireless communication system and the base station control method of the present invention, the power consumption of the entire base station can be reduced by adaptively starting and controlling the small base station according to the communication traffic.

It is a system configuration diagram in the present invention. It is a sequence diagram in the present invention. It is explanatory drawing showing the radio wave emission range which has established the radio link between a radio | wireless terminal and a large sized base station. It is explanatory drawing showing the radio wave emission range which has established the radio link between a radio | wireless terminal and a small base station. It is a functional block diagram of the large sized base station and management apparatus in this invention. It is a functional block diagram of the large sized base station carrying a management apparatus.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a system configuration diagram according to the present invention.

  According to FIG. 1, the wireless communication system includes a large base station 1, a plurality of small base stations 2, a management device 3, and a wireless terminal 4.

  The large base station 1 is a base station having a wide radio wave coverage (cover area), for example, a base station for mobile phone communication. The large base station 1 is provided with an array antenna or sector antenna having directivity, and one or more small base stations 2 exist in the cover area.

  The small base station 2 has a radio wave reach range smaller than that of the large base station 1 and is installed within the radio wave reach range of the large base station 1. The relationship may be a femtocell base station of the small base station 2 with respect to the macro cell base station for mobile phone communication of the large base station 1. Also, for example, the relationship of a microcell of a small base station to a macrocell of a large base station, or the relationship of a picocell of a small base station to a microcell of a large base station. May be. Further, the relationship may be a pico cell or a femto cell of a small base station with respect to a micro cell as a large base station.

  The management device 3 is connected to the large base station 1 and the small base station 2 via the communication carrier network, and controls activation of the small base station 2. The management device 3 may be provided integrally with the large base station 1. According to FIG. 1, one management device 3 is installed for one large base station 1, but a smaller number of management devices 3 are installed for a plurality of large base stations 1. It is also preferable.

  The small base station 2 is activated when an activation signal is received from the management device 3. The small base station 2 has a “Wake On LAN” function based on LAN technology, for example. “Wake On LAN” is a technology that can be turned on remotely via a network. Specifically, a special packet as an activation signal is transmitted to the target small base station. Specifically, there is a Magic Packet method.

  The wireless terminal 4 can communicate with both the large base station 1 and the small base station 2 via a wireless link. Here, in the wireless terminal 4, the communication method for communicating with the large base station and the communication method for communicating with the small base station may be the same or different. When the communication methods are different, the wireless terminal 4 includes different wireless communication interfaces.

  FIG. 2 is a sequence diagram in the present invention. 3 and 4 are explanatory diagrams showing a radio wave radiation range in which a radio link is established between a radio terminal and a large base station. 3 and 4 will be described in the description of the sequence of FIG.

  3 and 4, the large base station 1 divides the arrival direction of radio waves into a predetermined angle or a predetermined area range, and communicates with one or more wireless terminals 4 for each range. When the large base station 1 includes a sector antenna, all directions are divided into, for example, three sectors, and each sector communicates with one or more wireless terminals. The large base station 1 can detect a wireless terminal for each sector.

  When the large base station 1 includes an array antenna, a radio terminal may be detected by radiating directional radio waves in random directions (see, for example, Non-Patent Documents 7 and 8). . Furthermore, it is also preferable that the large base station estimates not only the direction but also the distance to the wireless terminal (see, for example, Non-Patent Document 3).

  2 to 4, the wireless terminal a and the wireless terminal b are located in the cover area of the small base station A. At this time, the small base station A and the small base station B are stopped and cannot communicate with the wireless terminal.

(S201) The wireless terminal a tries to communicate with the large base station 1 instead of the small base station A being stopped. The large base station 1 detects the arrival direction of the radio wave from the wireless terminal a by the array antenna or the sector antenna.

(S202) The large base station 1 transmits information on the arrival direction of the radio wave from the wireless terminal a to the management device 3. In the case of a sector antenna, the arrival direction of radio waves may be a sector number. Further, in the case of an array antenna, an identifier for each angle range divided in advance may be used.

(S203) The management device 3 determines whether the number of wireless terminals or the amount of communication traffic is greater than or equal to a predetermined number for each radio wave arrival direction. According to FIG. 2, it is assumed that the number of wireless terminals or the amount of communication traffic has not reached a predetermined number at the stage of S203.

(S204) In this case, the wireless terminal a establishes a wireless link with the large base station 1 and connects to the communication carrier network via the large base station 1.

(S211) Next, the wireless terminal b also tries to communicate with the large base station 1 instead of the small base station A being stopped. The large base station 1 detects the arrival direction of radio waves from the wireless terminal b. The state of S211 is illustrated in FIG.

(S212) The large base station 1 transmits the arrival direction information of the radio wave from the wireless terminal b to the management device 3.

(S213) The management device 3 determines whether the number of wireless terminals is equal to or greater than a predetermined number for each radio wave arrival direction. For example, when the predetermined number = 10, this determination is true when 10 wireless terminals are detected for the radio wave arrival direction. On the other hand, when the predetermined number = 1, this determination is true only when one wireless terminal is detected for the radio wave arrival direction. According to FIG. 2, it is assumed that the number of wireless terminals has reached a predetermined number in step S213.

  In addition, instead of the number of wireless terminals, a predetermined average unit time communication traffic volume may be used for determination. In this case, for example, when the predetermined amount = (average) 1.0 Mbps, the determination is true when communication traffic of 1.0 Mbps on average is detected for the radio wave arrival direction. Regarding this traffic volume, it is also preferable to set a predetermined value for each of the upstream and downstream, and to determine true when either reaches a predetermined amount.

(S221) The management device 3 transmits an activation signal to be activated to the small base stations A and B located in the arrival direction of the radio wave from the large base station 1. The activation signal may be a Wake On LAN packet, for example.

  It is also preferable that the activation signal includes geographical position range information of the small base station to be activated. In this case, the management apparatus 3 does not need to manage the position of each small base station in advance. The position range information is, for example, a latitude / longitude range.

(S222) The small base stations A and B are activated when the activation signal is received from the management device 3. The small base stations A and B have a Wake On LAN function in LAN technology, for example. When the small base stations A and B are activated, it is also preferable that the radio terminals a and b located in the vicinity of the base station A perform handover from the large base station 1 that has already established a link to the small base station A.

  Further, when the activation signal includes position range information, the small base stations A and B determine whether or not the position range of the small base stations A and B includes its own base station. Only if it is included, the small base stations A and B are activated.

  In addition, the small base stations A and B are activated by receiving an activation signal from the management device 3, and then activate a first timer that measures a first predetermined time. The first timer may be 30 minutes, for example. The first timer is reset every time the small base station is activated, and advances the countdown after activation.

(S223) Thereafter, the wireless terminals a and b establish a wireless link with the small base station A and connect to the communication carrier network via the small base station A. The state of S223 is shown in FIG. The small base station A starts after receiving the start signal from the management apparatus 3 and starts the second timer for measuring the second predetermined time after the communication desired by the user is completed. To do. It is also preferable to stop the first timer with the start of the second timer.

  In S222, although the small base station B is activated by receiving the activation signal from the large base station, there may be no active wireless terminal around it. In this case, it stops again due to the timeout of the first timer. Therefore, it is preferable that the first timer that is reset after the activation is shorter than the second timer that is reset after the user's desired communication ends.

(S224) The small base stations A and B automatically stop when the first timer or the second timer times out. According to FIG. 2, the small base station B where the wireless terminal is not in the vicinity stops earlier than the small base station A. Power consumption is reduced by reducing the time during which the small base station is wasted.

  As described above, the small base station 2 is activated only when the number of active wireless terminals 4 exceeds a predetermined number within the predetermined range divided by the large base station 1. Here, in order to avoid useless handover from the large base station to the small base station, it is also preferable to wait for the actual communication of the wireless terminal 4 until the small base station 2 is activated. However, in this case, depending on the start completion time of the small base station 2, there is a concern that the delay time until the start of communication in the wireless terminal 4 becomes long and usability is lowered. Therefore, it is also preferable that the wireless terminal 4 transmits a control message indicating the possibility of connection in the near future to the large base station 1 with an operation that may start communication as a trigger. The large base station 1 can start the target small base station group using the control message as a trigger. For example, when the terminal is a foldable terminal, the operation that may start communication is when the terminal is transitioned from the folded state to the opened state, when the terminal is a sliding terminal, and when the terminal is transitioned to the opened state by a sliding operation. is there.

  In this way, the large base station 1 starts the small base station 2 before the actual communication in the wireless terminal 4 starts, so that the wireless terminal 4 starts communication using the small base station 2 from the beginning of communication. can do.

  FIG. 5 is a functional configuration diagram of the large base station and the management apparatus according to the present invention.

  According to FIG. 5, the base station 1 includes an antenna (array antenna or sector antenna) 10, a phase level adjustment unit 11 for each antenna, a distributor 12, a radio wave arrival direction detection unit 121, and an encoding / decoding unit. 13, a telecommunications carrier network interface unit 14, and a radio wave arrival direction notifying unit 141.

  When the antenna 10 is an array antenna, it has two or more antenna elements in order to change the radiation direction of a radio wave having directivity. Moreover, when the antenna 10 is a sector antenna, it has an antenna element for every predetermined angle range.

  The phase level adjustment unit 11 adjusts the amplitude and phase of a signal to be transmitted and received for each antenna element. The distributor 12 distributes the transmission signal between the encoding / decoding unit 13 and the plurality of antenna elements. The encoding / decoding unit 13 performs encoding or decoding processing on a signal to be transmitted / received. The telecommunications carrier network interface unit 14 is connected to the telecommunications carrier network.

  The radio wave arrival direction detection unit 121 divides the radio wave arrival direction into a predetermined angle or a predetermined area range, and detects the arrival direction of the radio wave from the wireless terminal. When the antenna 10 is a sector antenna, the radio wave arrival direction detection unit 121 detects the arrival direction of the radio wave from the wireless terminal for each sector. When the antenna 10 is an array antenna, the radio wave arrival direction detection unit 121 detects the arrival direction of radio waves from the wireless terminal by changing the radio wave radiation direction by controlling the transmission array weight vector. Furthermore, the radio wave arrival direction detector 121 may further detect a distance from the wireless terminal.

  The radio wave arrival direction notifying unit 141 transmits information on the arrival direction of radio waves from the wireless terminal 4 to the management device 3. It is also preferable that the radio wave arrival direction notifying unit 141 further transmits information on the distance to the wireless terminal 4 to the management device 3.

  Next, the management device 3 includes a telecommunications carrier network interface unit 30, a terminal counting unit 31, a base station location management unit 32, and an activation signal transmission unit 33.

  The terminal counting unit 31 determines whether the number of wireless terminals or the amount of communication traffic is greater than or equal to a predetermined number for each radio wave arrival direction of the large base station. In addition, when the radio wave arrival direction detection unit 121 of the large base station can also detect the distance to the wireless terminal, the terminal counting unit 31 counts the number of wireless terminals for each area based on the radio wave arrival direction and distance. Alternatively, it is determined whether the amount of communication traffic is a predetermined number or more.

  The base station position management unit 32 manages position information in the large base station 1 and the plurality of small base stations 2. Therefore, for each area counted by the terminal counting unit 31, the small base station 2 located in the area is specified.

  When the number of wireless terminals or the amount of communication traffic is equal to or greater than a predetermined number, the activation signal transmission unit 33 transmits an activation signal to be activated to a small base station located in the arrival direction of the radio wave. The activation signal may include position range information of a small base station to be activated.

  FIG. 6 is a functional configuration diagram of a large base station equipped with a management device.

  According to FIG. 6, the management apparatus 3 is integrally mounted on the large base station 1, and each functional component is exactly the same as FIG. 5.

  The utilization form of the present invention will be described specifically. For example, a plurality of small base stations are installed in an office in a city center and a company house in a residential area. In the city center, there are many active wireless terminals during the day, but there are extremely few active wireless terminals at night. On the contrary, in the company house, there are few active wireless terminals during the day, but there are many active wireless terminals at night. Under such an environment, the number of wireless terminals existing around the small base station greatly fluctuates. However, if the start / stop of the small base station is controlled according to the day of the week or the time zone, the wireless terminal cannot connect to the base station because the active wireless terminal cannot cope with the sudden change of the base station. The inconvenience that it cannot be done occurs. For example, there may be a sudden increase in the number of active wireless terminals for accessing a specific Web site by holding an event. Therefore, the large base station detects the number of wireless terminals for each predetermined range, and the start / stop of the small base station is controlled based on the state, thereby reducing the load on the large base station where communication traffic is concentrated In addition, it is possible to cope with a special situation change in which the number of active wireless terminals increases rapidly.

  As described above in detail, according to the wireless communication system and the base station activation method of the present invention, the power consumption of the entire base station can be reduced by adaptively controlling the activation of the small base station according to the communication traffic. Can be reduced. In particular, the power consumption of the entire base station is reduced by reducing the time during which unnecessary small base stations are activated in vain. Moreover, even if the number of active wireless terminals increases or decreases depending on time and place, usability of the wireless terminals is not deteriorated. In particular, it functions effectively for starting / stopping small base stations arranged in office districts and residential areas.

  Various changes, modifications, and omissions of the above-described various embodiments of the present invention can be easily made by those skilled in the art. The above description is merely an example, and is not intended to be restrictive. The invention is limited only as defined in the following claims and the equivalents thereto.

DESCRIPTION OF SYMBOLS 1 Large base station 10 Array antenna, sector antenna 11 Phase / level adjustment part 12 Divider 121 Radio wave arrival direction detection part 13 Encoding / decoding part 14 Communication carrier network interface part 141 Radio wave arrival direction notification part 2 Small base station 3 Management Equipment 30 Communication carrier network interface unit 31 Terminal counting unit 32 Base station location management unit 33 Activation signal transmission unit 4 Wireless terminal

Claims (9)

Communicating with a large base station with a wide radio wave coverage, a small base station with a narrow radio wave coverage and within the radio wave coverage of the large base station, and both the large base station and the small base station A wireless communication system having a wireless terminal capable of
A management device for controlling activation of the small base station;
The large base station includes a radio wave arrival direction detection unit that detects a radio wave arrival direction from the radio terminal, and a radio wave arrival direction notification unit that transmits information on the radio wave arrival direction from the radio terminal to the management device. Have
The management device includes terminal counting means for determining whether the number of radio terminals or the amount of communication traffic is greater than or equal to a predetermined number for each radio wave arrival direction, and the number of radio terminals or the amount of communication traffic is greater than or equal to a predetermined number If there is an activation signal transmitting means for transmitting an activation signal to be activated to the small base station located in the arrival direction of the radio wave,
The small base station is activated when the activation signal is received from the management apparatus, and when there is no active wireless terminal around it, the small base station automatically stops after the first predetermined time has elapsed and is active around A wireless communication system , wherein when there is a wireless terminal , the wireless communication system automatically stops after a second predetermined time has elapsed after the communication of all the wireless terminals is completed . The large base station has a sector antenna,
2. The radio communication system according to claim 1, wherein the radio wave arrival direction detecting means divides the radio wave arrival direction into a predetermined angle or a predetermined area range and detects the radio wave arrival direction from the wireless terminal. The large base station has an array antenna,
The radio wave arrival azimuth detecting means divides the radio wave arrival azimuth into a predetermined angle or a predetermined area range, changes the radio wave radiation azimuth by controlling the transmission array weight vector, and determines the radio wave arrival azimuth from the wireless terminal. The wireless communication system according to claim 1, wherein the wireless communication system is detected. About the large base station,
The radio wave arrival direction detecting means further detects a distance between the wireless terminal,
The radio wave arrival direction notifying means further transmits information on the distance to the wireless terminal to the management device,
About the management device
The terminal counting means determines whether the number of wireless terminals or the amount of communication traffic is a predetermined number or more for each area based on the radio wave arrival azimuth and the distance,
The activation signal transmitting means transmits an activation signal to be activated to the small base station located in the range of the arrival direction and distance of the radio wave when the number of the wireless terminals or the communication traffic amount is a predetermined number or more. wireless communication system according to any one of claims 1 to 3, characterized in that. The wireless communication system according to any one of claims 1 to 4 , wherein the management device is integrally mounted on the large base station. The activation signal transmitting means of the management device includes, in the activation signal, location range information of a small base station to be activated,
The said small base station starts when the position of the said small base station is contained in the position range of the said position range information contained in the said starting signal, The any one of Claim 1 to 5 characterized by the above-mentioned. The wireless communication system according to 1. The large base station is a base station for mobile phone communication,
The wireless communication system according to any one of claims 1 to 6 , wherein the small base station is a base station for a femto cell, a pico cell, or a micro cell. The wireless terminal includes one communication interface of the same communication method or two communication interfaces of different communication methods in order to communicate with the large base station and the small base station. The wireless communication system according to any one of claims 1 to 7 . Communicating with a large base station with a wide radio wave coverage, a small base station with a narrow radio wave coverage and within the radio wave coverage of the large base station, and both the large base station and the small base station A base station activation method in a wireless communication system having a wireless terminal capable of,
A management device for controlling activation of the small base station;
A first step in which the large base station detects an arrival direction of radio waves from the wireless terminal;
A second step in which the large base station transmits information on the arrival direction of radio waves from the wireless terminal to the management device;
A third step in which the management device determines whether the number of wireless terminals or the amount of communication traffic is a predetermined number or more for each radio wave arrival direction;
A fourth step of transmitting an activation signal to be activated to the small base station located in the arrival direction of the radio wave, when the number of the wireless terminals or the amount of communication traffic is a predetermined number or more,
The small base station is activated when the activation signal is received from the management device, and when there is no active wireless terminal around it, the small base station automatically stops after the elapse of a first predetermined time and is active around And a fifth step of automatically stopping after a second predetermined time has elapsed after the communication of all the wireless terminals is completed when there are any wireless terminals .

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