JP5816104B2 - Base station and base station control method - Google Patents

Description

  The present invention relates to a base station operable in a sleep mode and a base station control method.

  In a conventional base station, traffic changes variously depending on the installation location and time zone. In order to provide a comfortable use environment for users, it is necessary to take measures such as installing a base station according to the peak traffic, but on the other hand, when the traffic drops, the base stations with overlapping coverage areas are wasted. As a result, the power of the entire system is wasted.

  As a means for solving this, the base station receives a downlink control signal transmitted from another base station (a control signal transmitted from another base station to the mobile terminal), and other base stations scattered around the same system. If the traffic of the base station is low (that is, the line is not used) and the traffic of other base stations is low, it recognizes that the traffic in the coverage area is low and A technique has been proposed in which a station is operated in a sleep mode to save power in the entire system (for example, Patent Document 1). Note that the sleep mode means that the reception operation of the radio signal in the base station is continued and the transmission operation is stopped. Since transmission of radio signals normally consumes a large amount of power, the power consumption can be reduced by switching from the normal operation mode to the sleep mode. The normal operation mode means performing a radio signal reception operation and transmission operation.

JP 2010-183303 A

  However, there is a problem in controlling the own base station to operate in the sleep mode only with the traffic information of the own base station and other neighboring base stations. That is, when the base station at the end of the system cover area operates in the sleep mode, the area coverage from other base stations is not performed and the coverage area of the entire system is reduced. This will be specifically described with reference to FIG.

  FIG. 4 is a schematic diagram of an arrangement of a plurality of base stations and a cover area. Each circle in FIG. 4 represents the coverage area of each base station, and a base station exists at the center of each circle. The mobile station can communicate with the base station inside the circle. For example, the base station A in FIG. 4 is located at the end of the cover area of the entire system. For example, the base station B is not located at the end of the cover area of the entire system.

  Here, when the base station B operates in the sleep mode, since the entire cover area of the base station B overlaps with the cover areas of other base stations, the cover area of the entire system does not decrease. On the other hand, when the base station A operates in the sleep mode, since there is an area that does not overlap with the cover area of the other base station in the cover area of the base station A, the area cover from the other base station is not performed, The coverage area of the entire system is reduced.

  Therefore, the object of the present invention made in view of the above problems is to prevent the base station located at the end of the cover area from operating in the sleep mode, without reducing the cover area of the entire system, and It is an object of the present invention to provide a base station and a base station control method capable of reducing the power consumption of the entire system by operating the base station in the sleep mode.

In order to solve the above problems, a base station according to the present invention
A base station operable in sleep mode,
An adaptive array antenna,
The wireless communication traffic between the local station and the wireless terminal is less than a predetermined threshold,
A downlink control signal of another base station in a plurality of directions is received by changing the antenna directivity of the adaptive array antenna, and the reception level of the downlink control signal in at least one of the plurality of directions is less than a predetermined threshold value In some cases, a radio control unit that controls the base station not to operate in a sleep mode;
It is characterized by providing.

The base station according to the present invention is
The radio control unit rotates the antenna directivity by approximately 360 degrees for each predetermined angle, and receives the downlink control signal in all directions.

  Further, in the base station according to the present invention, the radio control unit further detects traffic of another base station based on information included in the downlink control signal, and is included in the downlink control signal received in at least one direction. When the traffic based on the threshold is equal to or greater than a predetermined threshold, the base station is controlled not to operate in a sleep mode.

The base station control method according to the present invention includes:
A control method of a base station having an adaptive array antenna operable in a sleep mode,
Receiving downlink control signals of other base stations in a plurality of directions by changing the antenna directivity of the adaptive array antenna;
When the traffic of wireless communication between the own station and the wireless terminal is less than a predetermined threshold and the reception level of the downlink control signal in at least one of the plurality of directions is less than a predetermined threshold, the base station Controlling not to operate in sleep mode;
It is characterized by including.

The base station control method according to the present invention includes:
The step of receiving the control signal is characterized in that the antenna directivity is rotated by approximately 360 degrees for each predetermined angle and the downlink control signal in all directions is received.

The base station control method according to the present invention further includes:
Detecting traffic of another base station based on information included in the downlink control signal;
Controlling the base station not to operate in a sleep mode when the traffic based on information included in the downlink control signal received in at least one direction is greater than or equal to a predetermined threshold;
It is characterized by including.

  According to the base station and the base station control method of the present invention, the base station located at the end of the cover area is prevented from operating in the sleep mode, and the base station is put into sleep without reducing the cover area of the entire system. The power consumption of the entire system can be reduced by operating in the mode.

1 is a block diagram of a system including a base station according to an embodiment of the present invention. It is a figure showing the reception level of the downlink control signal of base station A and base station B. It is a flowchart which shows operation | movement of the base station which concerns on one Embodiment of this invention. It is the schematic of the arrangement | positioning of a some base station, and the cover area of the whole system.

  Embodiments of the present invention will be described below.

(Embodiment)
FIG. 1 is a block diagram of a system including a base station 1 according to an embodiment of the present invention. This system includes a base station 1, a mobile terminal 2, a communication network 3, and other base stations 1a to 1c. Although this system has a PHS system configuration, it may be a system other than PHS. Although only three other base stations are illustrated, it may be 2 or less or 4 or more.

  A base station 1 according to an embodiment of the present invention includes an adaptive array antenna 11, a radio unit 12, a radio control unit 13, and a network communication unit 14.

  The adaptive array antenna 11 includes a plurality of antennas. The adaptive array antenna 11 can change the antenna directivity in an arbitrary direction by adjusting the antenna weights of the plurality of antennas by a radio control unit 13 described later. 1 illustrates a configuration in which the adaptive array antenna 11 includes two antennas, but the configuration is not limited thereto, and the number of antennas may be three or more.

  The radio unit 12 transmits / receives a radio signal to / from the mobile terminal 2 through the adaptive array antenna 11 by the TDD method (time division duplex method). The radio unit 12 receives the downlink control signals of the other base stations 1a to 1c via the adaptive array antenna 11. The said downlink control signal is a control signal which other base stations 1a-1c transmit with respect to a subordinate mobile terminal. The base station 1 receives the downlink control signal and refers to information included in the downlink control signal, so that any one of the other base stations 1a to 1c that has transmitted the downlink control signal operates in the normal operation mode. And the traffic of the other base stations 1a to 1c can be recognized. 1 illustrates only one mobile terminal (mobile terminal 2), the present invention is not limited to this, and the base station 1 may wirelessly communicate with a plurality of mobile terminals.

  The radio control unit 13 performs various controls related to the base station 1. Specifically, the radio control unit 13 operates the base station 1 in a sleep mode or a normal operation mode under a predetermined condition.

  In addition, the wireless control unit 13 determines whether the wireless communication traffic with the portable terminal 2 by the wireless unit 12, that is, the traffic of the base station 1 is equal to or greater than a first threshold value. When the traffic of the base station 1 is equal to or higher than the first threshold, the radio control unit 13 is in communication with the mobile terminal 2 in the cover area of the base station 1 and therefore does not operate the base station 1 in the sleep mode. To control. That is, the radio control unit 13 operates the base station 1 in the normal operation mode.

  The wireless control unit 13 performs AAA control (Adaptive Array Antenna control) of the adaptive array antenna 11 to change the antenna directivity. Then, the radio control unit 13 receives the downlink control signals in a plurality of directions through the adaptive array antenna 11 and the radio unit 12 while changing the antenna directivity of the adaptive array antenna 11. Preferably, the radio control unit 13 rotates the antenna directivity of the adaptive array antenna 11 by approximately 360 degrees for each predetermined angle, and receives downlink control signals in all directions via the adaptive array antenna 11 and the radio unit 12. .

  Further, the radio control unit 13 measures the reception level of the downlink control signal received in a plurality of directions, and determines whether or not the reception level is greater than or equal to the second threshold value. When the reception level in at least one direction is less than the second threshold, the wireless control unit 13 determines that the base station 1 is located at the end of the cover area of the entire system and does not operate in the sleep mode. Control. That is, the radio control unit 13 operates the base station 1 in the normal operation mode.

  On the other hand, if the reception level in all directions is equal to or greater than the second threshold, the radio control unit 13 determines that the base station 1 is not located at the end of the cover area of the entire system, and the base station 1 under predetermined conditions. Set to sleep.

  Further, the radio control unit 13 detects traffic of another base station (any one of the other base stations 1a to 1c) that has transmitted the downlink control signal based on the downlink control signal received in each direction. Then, the wireless control unit 13 determines whether the traffic is equal to or greater than a third threshold value. When the traffic of at least one other base station (other base stations 1a to 1c) is equal to or greater than the third threshold, the radio control unit 13 performs, for example, a handover caused by movement of the mobile terminal 2 connected to the other base station. Due to the influence, it is determined that there is a high possibility that traffic will fluctuate around the base station 1, and the base station 1 is controlled not to operate in the sleep mode. That is, the radio control unit 13 operates the base station 1 in the normal operation mode.

  Then, the radio control unit 13 is configured such that when the traffic of the base station 1 is less than the first threshold and all the traffic of the other base stations 1a to 1c based on the downlink control signal received in each direction is less than the third threshold. In some cases, since the traffic of the base station 1 and the other base stations 1a to 1c is small, the base station 1 is operated in the sleep mode. The sleep mode continues for a predetermined time, and when there is an instruction to cancel the sleep mode for a predetermined time or by external control, the radio control unit 13 stops the base station 1 from operating in the sleep mode.

  The network communication unit 14 is connected to the upper network via the communication network 3 and performs network communication with the upper network.

  FIG. 2 shows the reception level of the downlink control signal in each direction. 2A and 2B correspond to the base station A and the base station B in FIG. 4, respectively. Here, in FIGS. 2A and 2B, the horizontal axis is the azimuth, and 0 degrees (deg) is the north direction. The vertical axis represents the reception level of the downlink control signal. The second threshold is 30 dBμV. Hereinafter, a method in which the base station A and the base station B measure the reception level of the downlink control signal will be specifically described. Note that both the base station A and the base station B have the configuration of the base station 1 according to the present invention and will be described using the reference numerals of the base station 1.

  The radio controller 13 of the base station A changes the antenna directivity of the adaptive array antenna 11 every 45 degrees in the clockwise direction, and each direction (that is, 0 degrees, 45 degrees, 90 degrees, 135 degrees, 180 degrees, 225 degrees, 270 degrees, 315 degrees, 360 degrees) are received, and the reception level is measured. In FIG. 2A, the reception levels in each direction are 40 dBμV, 80 dBμV, 80 dBμV, 70 dBμV, 40 dBμV, 15 dBμV, 5 dBμV, 10 dBμV, and 40 dBμV, respectively. Here, at 225 degrees, 270 degrees, and 315 degrees, which is less than the second threshold value, since the base station A is located at the end of the cover area of the entire system, the radio control unit 13 sets the base station A in the sleep mode. Control not to operate with.

  Similarly, the radio control unit 13 of the base station B changes the antenna directivity of the adaptive array antenna 11 every 45 degrees in the clockwise direction, and each direction (that is, 0 degree, 45 degrees, 90 degrees, 135 degrees, 180 degrees). , 225 degrees, 270 degrees, 315 degrees, 360 degrees) and receive the downlink control signal, and measure the reception level. In FIG. 2B, the reception levels in each direction are 80 dBμV, 70 dBμV, 80 dBμV, 85 dBμV, 80 dBμV, 90 dBμV, 80 dBμV, 70 dBμV, and 80 dBμV, respectively. Here, although it is not less than the second threshold value in all directions (here, all directions), since the base station B is not located at the end of the cover area of the entire system, the radio control unit 13 sets the base station B to a predetermined value. Operate in sleep mode under the following conditions.

  The radio control unit 13 rotates the antenna directivity in the clockwise direction, but may be in the counterclockwise direction. Further, the wireless control unit 13 rotates the antenna directivity of the adaptive array antenna 11 by 360 degrees every 45 degrees, but is not limited to this. For example, the wireless control unit 13 may rotate approximately 360 degrees every predetermined angle. It may be changed every degree.

  Next, the operation of the base station 1 according to the present invention will be described with reference to the flowchart shown in FIG.

  First, the wireless control unit 13 of the base station 1 determines whether or not the wireless communication traffic with the mobile terminal 2 by the wireless unit 12, that is, the traffic of the base station 1 is equal to or greater than a first threshold (step S1). If it is greater than or equal to the first threshold, the process proceeds to step S2, and if it is less than the second threshold, the process proceeds to step S3.

  When the traffic of the base station 1 is equal to or greater than the first threshold, the radio control unit 13 is in communication with the mobile terminal 2 within the coverage area of the base station 1, and therefore controls the base station 1 not to operate in the sleep mode. To do. That is, the radio control unit 13 causes the base station 1 to operate in the normal operation mode (step S2).

  On the other hand, when the traffic of the base station 1 is less than the first threshold, the radio control unit 13 changes the antenna directivity of the adaptive array antenna 11 to send downlink control signals in a plurality of directions to the adaptive array antenna 11 and the radio unit 12. Receive via. Preferably, the radio control unit 13 rotates the antenna directivity of the adaptive array antenna 11 by approximately 360 degrees for each predetermined angle, and receives downlink control signals in all directions via the adaptive array antenna 11 and the radio unit 12. . Then, the wireless control unit 13 measures the reception level of the downlink control signal received in a plurality of directions, and determines whether or not all the reception levels are equal to or higher than the second threshold (step S3).

  If the reception level of the downlink control signal in at least one direction is less than the second threshold in step S3, the radio control unit 13 determines that the base station 1 is located at the end of the cover area of the entire system, and sleeps. Control not to operate in mode. In step S2, the radio control unit 13 operates the base station 1 in the normal mode.

  On the other hand, if the reception level in all directions is greater than or equal to the second threshold value in step S3, the radio control unit 13 determines that the base station 1 is not located at the end of the cover area of the entire system. In this case, the radio control unit 13 detects traffic of another base station (any one of the other base stations 1a to 1c) that has transmitted the downlink control signal based on the downlink control signal received in each direction. Then, the radio control unit 13 determines whether or not the traffic of at least one other base station (the other base stations 1a to 1c) is greater than or equal to the third threshold (step S4).

  In step S4, when the traffic of at least one other base station (other base stations 1a to 1c) is equal to or greater than the third threshold, the radio control unit 13 is highly likely to change the traffic around the base station 1. And the base station 1 is controlled not to operate in the sleep mode. In step S2, the radio control unit 13 operates the base station 1 in the normal operation mode.

  On the other hand, in step S4, when all the traffic of the other base stations 1a to 1c based on the downlink control signal received in each direction is less than the third threshold, the traffic of the base station 1 and the other base stations 1a to 1c is small. The base station 1 is operated in the sleep mode (step S5).

  Subsequently, the wireless control unit 13 determines whether or not there is an instruction to cancel the sleep mode by elapse of a predetermined time or by external control (step S6). When there is no sleep mode cancellation instruction, the process returns to step S5 and the radio control unit 13 causes the base station 1 to continue the sleep mode. On the other hand, if there is an instruction to cancel the sleep mode, the process returns to step S1. That is, the radio control unit 13 causes the base station 1 to operate in the normal operation mode or the sleep mode under a predetermined condition.

  As described above, according to the present invention, the radio control unit 13 changes the AAA antenna directivity of the adaptive array antenna 11 and measures the reception level of the downlink control signal received in a plurality of directions. It is possible to prevent the located base station 1 from operating in the sleep mode, and to reduce the power consumption of the entire system by operating the base station 1 in the sleep mode without reducing the cover area of the entire system.

  Further, according to the present invention, the radio control unit 13 rotates the antenna directivity of the adaptive array antenna 11 by approximately 360 degrees for each predetermined angle, and transmits the downlink control signal in all directions to the adaptive array antenna 11 and the radio unit 12. Therefore, the situation of other base stations in all directions can be grasped.

  Although the present invention has been described based on the drawings and examples, it should be noted that those skilled in the art can easily make various modifications and corrections based on the present disclosure. Therefore, it should be noted that these variations and modifications are included in the scope of the present invention. For example, the functions included in each means, each step, etc. can be rearranged so that there is no logical contradiction, and a plurality of means, steps, etc. can be combined or divided into one. .

DESCRIPTION OF SYMBOLS 1 Base station 11 Adaptive array antenna 12 Radio | wireless part 13 Wireless control part 14 Network communication part 2 Portable terminal 3 Communication network 1a, 1b, 1c Other base stations

Claims (6)

A base station operable in sleep mode,
An adaptive array antenna,
The wireless communication traffic between the local station and the wireless terminal is less than a predetermined threshold,
A downlink control signal of another base station in a plurality of directions is received by changing the antenna directivity of the adaptive array antenna, and the reception level of the downlink control signal in at least one of the plurality of directions is less than a predetermined threshold value In some cases, a radio control unit that controls the base station not to operate in a sleep mode;
A base station comprising:   The base station according to claim 1, wherein the radio control unit rotates the antenna directivity by approximately 360 degrees for each predetermined angle and receives the downlink control signal in all directions.   The radio control unit further detects traffic of another base station based on information included in the downlink control signal, and the traffic based on information included in the downlink control signal received in at least one direction is greater than or equal to a predetermined threshold value The base station according to claim 1, wherein the base station is controlled not to operate in a sleep mode. A control method of a base station having an adaptive array antenna operable in a sleep mode,
Receiving downlink control signals of other base stations in a plurality of directions by changing the antenna directivity of the adaptive array antenna;
When the traffic of wireless communication between the own station and the wireless terminal is less than a predetermined threshold and the reception level of the downlink control signal in at least one of the plurality of directions is less than a predetermined threshold, the base station Controlling not to operate in sleep mode;
A base station control method including:   5. The base station according to claim 4, wherein the step of receiving the control signal comprises rotating the antenna directivity approximately 360 degrees for each predetermined angle and receiving the downlink control signal in all directions. Control method. The base station control method further includes:
Detecting traffic of another base station based on information included in the downlink control signal;
Controlling the base station not to operate in a sleep mode when the traffic based on information included in the downlink control signal received in at least one direction is greater than or equal to a predetermined threshold;
The base station control method according to claim 4 or 5, characterized by comprising:

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